Open surgical repair of abdominal aortic aneurysm

INTRODUCTION — Replacement of the abdominal aorta for the repair of abdominal aortic aneurysm (AAA) was first described in 1952 [1]. While prosthetic materials have replaced the arterial homografts used originally, the technical conduct of the operation has remained largely unchanged for nearly 70 years. Open surgical repair of abdominal aneurysms has proven to be safe, widely available, effective in preventing aneurysm rupture, and remarkably durable [2]. Open repair of abdominal aortic aneurysm is performed under general anesthesia with appropriate monitoring of volume status and fluid administration and transfusion, as needed. Repair of the aorta is carried out in a systematic fashion that involves clamping the aorta to stop blood flow, opening the aneurysm to remove thrombus and debris from within the aorta, and suturing a synthetic graft to replace the diseased arterial segment.

The preoperative evaluation and preparation, operative technique, and postoperative care and follow-up of patients undergoing AAA repair is reviewed here. General issues regarding the management of AAA and the surgical and endovascular management of ruptured AAA are discussed elsewhere. (See "Management of asymptomatic abdominal aortic aneurysm" and "Management of symptomatic (non-ruptured) and ruptured abdominal aortic aneurysm" and "Surgical and endovascular repair of ruptured abdominal aortic aneurysm".)

Anesthesia choices, monitoring, and the conduct of anesthesia for open aortic surgery is reviewed separately. (See "Anesthesia for open abdominal aortic surgery".)

INDICATIONS FOR OPEN REPAIR — The indications for the repair of abdominal aortic aneurysm (AAA) are discussed in detail elsewhere and include symptomatic aneurysm of any size (eg, abdominal, back or flank pain, evidence of embolization, frank rupture), asymptomatic aneurysm ≥5.5 cm in males and >5.0 cm in females [3,4], rapidly expanding AAA, AAA associated with another arterial disease (especially iliac aneurysm), infected AAA, and complications following endovascular repair necessitating early or late conversion to an open AAA repair (table 1) [5]. The clinical evaluation and management of AAA are discussed separately. (See "Management of asymptomatic abdominal aortic aneurysm", section on 'Summary of indications for elective AAA repair' and "Management of symptomatic (non-ruptured) and ruptured abdominal aortic aneurysm", section on 'Approach to AAA associated with symptoms'.)

Contraindications — Open repair of abdominal aortic aneurysm is contraindicated in patients in whom the estimated risk of the procedure exceeds the risk of rupture. These risk factors are discussed below. (See 'Medical risk assessment' below.)

Relative contraindications to open surgical repair of AAA in the era of endovascular aneurysm repair may include the following: hostile abdomen, obesity, major cardiac or pulmonary comorbidities, and limited life expectancy. (See "Management of asymptomatic abdominal aortic aneurysm", section on 'Open versus endovascular aneurysm repair' and "Management of symptomatic (non-ruptured) and ruptured abdominal aortic aneurysm".)

ANATOMIC CONSIDERATIONS — The abdominal aorta is defined as aneurysmal when a localized dilation is more than 50 percent larger than the normal adjacent aortic diameter [6]. From a practical standpoint, an infrarenal aortic diameter greater than 3.0 cm (measured outer wall-to-outer wall) is considered aneurysmal for most individuals [7]. Aortoiliac anatomy is discussed in detail elsewhere. (See "Overview of abdominal aortic aneurysm", section on 'Definitions and aortoiliac anatomy'.)

Aneurysm extent — Abdominal aortic aneurysms (AAAs) are commonly described based on the relationship to the renal arteries as infrarenal, juxtarenal, pararenal, and suprarenal (figure 1). AAAs most often occur in the segment of aorta between the renal arteries and the bifurcation of the aorta. Only 5 percent of aortic aneurysms involve the renal or visceral arteries (figure 2). Up to 40 percent of AAAs are associated with iliac artery aneurysm(s). The presence of iliac artery aneurysm may necessitate placement of a bifurcated graft. The extent of the aneurysm also affects the surgical approach. (See 'Incision and aortic exposure' below.)

PREOPERATIVE EVALUATION

Medical risk assessment — Perioperative morbidity and mortality are increased in patients with advanced age; female sex; and severe cardiac, pulmonary, liver, or kidney disease [8,9]. Preoperative consultation with the anesthesia team is appropriate. Medical risk assessment and factors that assist in determining the appropriateness of open surgical repair for a specific patient are discussed elsewhere. (See "Anesthesia for open abdominal aortic surgery", section on 'Preanesthetic consultation' and "Management of asymptomatic abdominal aortic aneurysm", section on 'Medical risk assessment'.)

Patients undergoing abdominal aortic aneurysm (AAA) repair are often taking medications for secondary prevention of cardiovascular events. Patients who are currently taking aspirin, beta blockers, and lipid-lowering therapy should continue these medications throughout the perioperative period. Many surgeons prefer to discontinue clopidogrel prior to surgery if not indicated for coronary drug-eluting stent or recent carotid stent. For patients who are not currently taking these medications, whether or not and when to initiate therapy is reviewed separately. (See "Evaluation of cardiac risk prior to noncardiac surgery", section on 'Summary and recommendations'.)

The management of other medications common in this population is discussed in detail elsewhere. (See "Perioperative medication management".)

Estimation of perioperative risk — A number of risk calculators have been developed to estimate the risk of perioperative adverse events. The updated guidelines from the Society for Vascular Surgery (SVS) endorse the use of a scoring system derived from data collected by the Vascular Study Group of New England, part of the National Vascular Quality Initiative (VQI) [10].

Using this dataset, major factors that affect in-hospital mortality after elective AAA repair were identified. The strongest risk factors for mortality in order of significance were:

●Placement of a suprarenal clamp

●Open aortic surgery

●Chronic obstructive pulmonary disease (COPD)

●Renal dysfunction (particularly serum creatinine >2.0 mg/dL)

●AAA diameter >6.5 cm

●Advanced age

●Cerebrovascular disease

●Female sex

●Heart disease

Using a simple point system, the VQI risk calculator recognizes four risk categories: low (<1 percent), moderate (1 to 5 percent), high (8 to 20 percent), and prohibitive risk (>30 percent). As an example, the estimated risk of mortality with open AAA repair for a 55-year-old otherwise healthy woman with a 5.0-cm aneurysm is <1 percent. By comparison, a 75-year-old man with a 6.5-cm juxtarenal AAA and a history of COPD, coronary artery disease, and chronic kidney disease with a serum creatinine level >2.0 has an estimated risk of mortality of more than 40 percent. It is recommended that the estimated risk of mortality be included during informed consent discussions.

The SVS also recommends that open AAA repair be limited to hospitals with a documented mortality of <5 percent and that perform at least 10 open aortic procedures annually [4]. Data from the International Consortium of Vascular Registries indicated that centers with an annual volume of at least 13 open aneurysm repairs were associated with lower in-hospital mortality in comparison to lower volume centers [11]. The European Society for Vascular Surgery has recommended that open AAA repair be restricted to centers with an annual open and endovascular volume in excess of 20 AAA repairs [12].

Decreasing open AAA volumes may have significant implications for training the next generation of vascular surgeons [13,14].

Vascular evaluation — The status of the peripheral circulation should be assessed prior to open repair of AAA. The clinical examination should focus on the identification of coexistent aneurysms (eg, iliac aneurysm, popliteal aneurysm) and/or occlusive disease. The diagnosis and management of peripheral aneurysms and peripheral artery disease are discussed elsewhere. (See "Iliac artery aneurysm" and "Popliteal artery aneurysm" and "Clinical features and diagnosis of lower extremity peripheral artery disease".)

For patients who present with lower extremity symptoms such as claudication, noninvasive vascular studies (ankle-brachial index, segmental pressures) should be performed. The character and location of peripheral pulses should be noted for comparison at the completion of the aneurysm repair. If computed tomography (CT) imaging of the aneurysm has not included lower extremities, duplex arterial imaging can be performed to assess the distal vasculature, rather than repeat CT or arteriography. (See "Noninvasive diagnosis of upper and lower extremity arterial disease".)

The risk of perioperative death is increased in patients with peripheral artery disease and should be taken into account when choosing between endovascular aneurysm and open repair [15]. The preoperative sexual health of the patient should be documented. In the past, postoperative sexual dysfunction was thought to be related to pelvic arterial insufficiency alone, or in combination with intraoperative injury to the autonomic nerves located to the left of the aortic bifurcation. It has been demonstrated that preoperative sexual dysfunction is common in the population of patients with abdominal aneurysm. In the Dutch Randomized Endovascular Aneurysm Management (DREAM) trial [16,17], more than 60 percent of patients admitted symptoms of sexual dysfunction preoperatively. Repair of AAA, open or endovascular, was associated with modest deterioration in reported sexual function in the early postoperative period, which casts doubt on the true incidence of sexual dysfunction that results directly from aneurysm repair. Nonetheless, every effort should be made to avoid autonomic nerve injury and preserve arterial blood flow to the internal iliac arteries, whenever possible.

Aortic imaging — Prior to open AAA repair, CT angiography is the imaging test of choice to evaluate the location (eg, infrarenal, suprarenal) and anatomic features (eg, extent of thrombus, calcification, inflammation) of the aneurysm and to identify other abnormalities (eg, retrocaval left renal vein, accessory renal arteries, horseshoe kidney) that may alter the approach to repair. CT has replaced conventional contrast arteriography in the preoperative assessment of aneurysm, but the latter may be appropriate to answer specific anatomic questions (eg, adequacy of pelvic collateral circulation) or to perform preoperative catheter-based intervention in selected patients. (See "Clinical features and diagnosis of abdominal aortic aneurysm", section on 'Diagnosis'.)

The extent of exposure during open surgery depends upon the extent of the aneurysm and the identification of suitable arterial sites for clamping and for suturing the proximal and distal anastomoses. In general, preoperative imaging should aid in predicting the proximal and distal extent of exposure. Imaging studies should be reviewed and the amount of thrombus and location of calcification carefully assessed to determine the best locations for arterial clamping. In addition, the presence and location of distal occlusive disease should be identified in patients with diminished femoral, popliteal, or foot pulses.

The vascular supply to the intestines should also be evaluated preoperatively. Occlusive vascular disease is frequently present in the visceral circulation in patients with AAA. As an example, the presence of an enlarged meandering mesenteric artery on preoperative imaging should alert the surgeon to the possibility of significant stenosis or occlusion in the superior mesenteric artery. It is incumbent on the surgeon to assure the adequacy of visceral perfusion prior to completion of the case. In some cases, it may be best to revascularize the superior mesenteric artery (SMA) at the time of open aneurysm repair [18,19]. Alternatively, percutaneous visceral revascularization may be performed preoperatively or in conjunction with open repair [20]. The status of the SMA also influences the management of the inferior mesenteric artery at the time of surgery. (See 'Handling the inferior mesenteric artery' below.)

Horseshoe kidney is a congenital fusion anomaly wherein the lower pole of the one kidney is fused anteriorly across the aorta to the contralateral kidney; fusion at the lower poles is most common. Horseshoe kidney is associated with urologic anomalies including ureteral duplication, ectopic ureter, retrocaval ureter, and supernumerary renal arteries. The location, size, and importance of various renal vessels needs to be determined to prevent postoperative renal ischemia, segmental infarction, hypertension, and acute renal injury. CT angiogram is usually adequate to visualize renal artery anatomy, but conventional arteriography may occasionally be needed. Small vessels originating from the isthmus may be amenable to sacrifice. A retroperitoneal approach is preferred for open AAA repair associated with horseshoe kidney; however, the presence of large renal arteries originating from the iliac arteries will contraindicate a retroperitoneal approach. General features of renal fusion abnormalities are discussed elsewhere. (See "Renal ectopic and fusion anomalies", section on 'Horseshoe kidney'.)

Inflammatory aneurysm is identified by the presence of contrast-enhancing thickening of the aneurysm wall and perianeurysmal fibrosis. The ureters may be drawn towards the inflammatory process involving the aorta. Approximately 3 percent of abdominal aortic aneurysms have an inflammatory component [21]. Inflammatory aneurysms are more often symptomatic, and perioperative mortality rates appear to be higher following open repair compared with noninflammatory aneurysms. As with any AAA, a choice between open versus an endovascular approach to inflammatory AAA should be based upon patient characteristics and anatomic suitability [22-26]. (See "Clinical features and diagnosis of abdominal aortic aneurysm", section on 'Infected versus inflammatory AAA'.)

Suitability for endovascular repair — Prior to embarking on open repair of AAA, it is important to determine if the patient would be better served by endovascular aneurysm repair (EVAR). Perioperative morbidity and mortality is lower for elective endovascular compared with open surgical repair of AAA, but long-term outcomes have not shown to be different [27,28]. Although advances in endovascular aneurysm repair have extended its use to a large proportion of the elective AAA repair population, open abdominal aortic aneurysm repair is still needed for patients with anatomy outside device protocols [29]. For patients with juxtarenal aneurysm, the choice between complex endovascular treatment using fenestrated or branched grafts versus open repair requiring suprarenal clamping can be particularly challenging. Data suggest that open surgical repair of juxtarenal abdominal aortic aneurysms in older adults is associated with similar 30-day mortality compared with fenestrated endovascular grafting [30]. Criteria for endovascular repair and a decision for open versus endovascular AAA repair are discussed in detail elsewhere. (See "Endovascular repair of abdominal aortic aneurysm", section on 'Anatomic suitability' and "Management of asymptomatic abdominal aortic aneurysm", section on 'Choice of AAA repair approach'.)

PREPARATION — Prior to surgery, preoperative baseline laboratories including complete blood count, chemistry panel, and coagulation studies should be obtained. These tests will serve as baseline values for comparison with intraoperative and postoperative studies. The blood bank should determine the patient's blood type and perform a screen for common antibodies.

Blood for transfusion — In a review of nearly 4000 open aneurysm operations in the Vascular Quality Initiative database, transfusions were required in 37.5 percent of these cases [31]. To minimize the need for cross-matched blood, we recommend the use of blood salvage systems (eg, CellSaver) [32]. (See "Surgical blood conservation: Intraoperative blood salvage".)

We suggest that no more than 2 units of typed and cross-matched packed red blood cells should be made available at the beginning of elective open AAA repair. Cross-matched blood can usually be supplied within a reasonable timeframe if additional blood is needed. Preparing fully cross-matched blood that is not transfused is inefficient since the blood is not available for others, expensive, and may strain the manpower in the blood bank; however, the lag time needed to prepare cross-matched blood depends upon the delivery capacity of the local blood bank and transfusion services. The presence of unusual antibodies will, by necessity, require preoperative consultation with the appropriate institution-specific hematology resources.

For patients with religious beliefs that impact their willingness to accept banked blood, it is important that the surgeon and patient (and patient proxy) have the acceptable conditions governing blood-product transfusion precisely described and recorded in the chart. It should be noted that the surgeon is not compelled to perform an operation under conditions that they consider unsafe.

Prophylactic antibiotics — Prophylactic antibiotics are recommended for patients undergoing arterial surgery involving the placement of prosthetic material. Appropriate antibiotics are given in the table (table 2). (See "Antimicrobial prophylaxis for prevention of surgical site infection in adults".)

Aortic graft infection is an uncommon but catastrophic complication. A review of data from the Washington State Comprehensive Hospital Abstract Reporting System (CHARS) identified 13,902 patients who underwent AAA repair (90 percent open). Bloodstream infection and postoperative surgical site infection were significantly associated with subsequent aortic graft infection, which occurred at a mean of three years following the procedure [33]. In addition to maintenance of strict sterile technique, the timely administration of prophylactic antibiotics has been shown to reduce the incidence of surgical site infection and graft infection.

The choice of therapeutic antibiotics in patients found to have infected aneurysm or infected aortic graft will depend upon blood culture and sensitivity results. For patients who have been started on antibiotics due to concerns for infection, antibiotics should be re-dosed prior to surgery.

Thromboprophylaxis — The incidence of deep vein thrombosis following AAA repair ranges from 1 to 10 percent [34-37]. Most patients undergoing aortic surgery are at moderate-to-high risk for thromboembolism based upon age, comorbidities, and procedure duration (table 3). For moderate- to high-risk patients, pharmacologic thromboprophylaxis is recommended [38,39]. However, we omit pharmacologic thromboprophylaxis for patients with ruptured AAA or impending rupture. We prefer using unfractionated heparin or, alternatively, low-molecular-weight heparin (LMWH), rather than Fondaparinux for pharmacologic prophylaxis given the potential need for reversal if there are bleeding problems during the surgery. (See "Surgical and endovascular repair of ruptured abdominal aortic aneurysm" and "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients", section on 'Selecting thromboprophylaxis' and "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients".)

We also suggest using mechanical thromboprophylaxis for all patients undergoing open AAA repair who will not have their entire lower extremities prepared within the field. In general, this means knee-high rather than thigh-high intermittent pneumatic compression given the potential need in most patients to access the groin vessels during surgery. (See 'Incision and aortic exposure' below.)

One survey from Great Britain found a wide diversity in perioperative thromboprophylaxis strategies among vascular surgeons [40]. This variability may be due to firmly held beliefs about the perceived beneficial effects of routine systemic anticoagulation during aortic cross-clamping and concerns over intra- or postoperative bleeding with superimposed thromboprophylaxis. However, the administration of intraoperative heparin should not be misconstrued as an appropriate substitute for recommended strategies for postoperative thromboprophylaxis. Systemic anticoagulation is not administered until the aortic dissection is completed, which can be one hour (or longer) following the induction of anesthesia.

Randomized trials in patients undergoing aortic procedures have been small, with methodological problems and inconsistent findings [36,37,41]; thus, recommendations for thromboprophylaxis in aortic surgery are based upon higher-quality evidence in general and abdominal-pelvic surgery [39].

●The earliest trial in patients undergoing aortic surgery was terminated early due to excess bleeding [41].

●A later trial randomly assigned 100 patients to thromboprophylaxis using unfractionated heparin versus no heparin and found no significant difference in the incidence of deep vein thrombosis between the groups (one deep vein thrombosis [DVT] in each group for an incidence of 2 percent) [36].

●In another trial, 234 patients undergoing AAA repair (n = 75), aorto-femoral bypass (n = 71), or lower extremity bypass (n = 87) were assigned to unfractionated heparin or enoxaparin [37]. In this study, the incidence of DVT following AAA repair was 8 percent, and there were no significant differences between the groups. No pulmonary embolisms occurred. Postoperative bleeding events did not differ significantly between the groups.

Bowel preparation — We suggest not routinely administering mechanical or antibiotic bowel preparation prior to elective open AAA repair. Advocates suggest that bowel preparation reduces the risk of bowel ischemia and reduces the time to resumption of diet, but there is no objective evidence to support this practice.

In addition to these issues, bowel preparation can be associated with volume and electrolyte depletion and is unpleasant for the patient. Controlled studies have compared enhanced recovery after surgery (ERAS) protocols with traditional care [42-44]. In one trial [42,43], the following treatments were used in the ERAS group.

●NO bowel preparation (versus 3 liters of GoLYTELY)

●Reduced preoperative fasting (two versus six hours)

●Patient-controlled epidural analgesia versus patient-controlled intravenous opioids

●Early postoperative feeding and mobilization versus awaiting definitive bowel function

●Postoperative fluid restriction versus more liberal fluids (1 versus 3 liters per 24 hours)

Patients in the ERAS protocol did at least as well as those who received traditional care. With respect to bowel function, nine patients in the traditional care group had postoperative ileus compared with three in the ERAS protocol. Ischemic colitis occurred in one patient who did not receive bowel preparation compared with no patients among those who received bowel preparation.

Ureteral stent placement — Prophylactic ureteral stent placement is not routinely needed prior to open aneurysm repair. In selected patients with significant retroperitoneal adhesions due to prior surgery, infection, or inflammation, the placement of ureteral stents may be useful [45]. Although prophylactic ureteral stent placement does not reduce the risk of ureteral injury, it increases the likelihood of detection when injury occurs. (See "Placement and management of indwelling ureteral stents", section on 'Prophylactic'.)

GRAFTS FOR OPEN AORTIC REPAIR — Options for aortic replacement include polyester (eg, Dacron), polytetrafluoroethylene (PTFE), and autogenous artery or vein. The graft diameter should be selected to match the diameter of the aorta. Interestingly, the diameter of an open surgical graft is invariably smaller than the diameter of an endograft used in the same location.

The most widely used material is woven polyester fabric. Although favored by some surgeons for its handling qualities, knitted polyester suffers from high porosity as well as a tendency to dilate over time. Conventional woven polyester, on the other hand, is extremely durable but is somewhat less pliable than knitted fabric. Collagen or albumin coating has eliminated the need to "pre-clot" polyester grafts with whole blood. Most modern grafts employ a hybrid structure that combines the benefits of both knitted and woven fabrics (eg, woven double velour), which is easy to handle, durable, and appropriately porous.

PTFE grafts may be more resistant to infection than polyester, although the data supporting this claim are limited. Suture hole bleeding is a problem and may require the use of special large-diameter sutures or topical hemostatic agents for control. (See 'Preventing and troubleshooting hemorrhage' below and "Fibrin sealants" and "Overview of topical hemostatic agents and tissue adhesives", section on 'Fibrin sealant'.)

Autogenous conduit, such as femoral vein, is usually reserved for the circumstance when gross infection is present [46,47]. Because of the time needed to harvest the vein, sometimes bilaterally, femoral vein has limited use in the routine open surgical treatment of abdominal aortic aneurysm (AAA). Femoral vein may be appropriate in some patients with small iliac or femoral arteries if there is an unacceptable size mismatch between the graft limbs and distal anastomotic site.

INCISION AND AORTIC EXPOSURE

Approach to the aorta — The abdominal aorta can be exposed through a transperitoneal or retroperitoneal approach. A retroperitoneal approach allows complete exposure of the abdominal aorta in much the same fashion as the transabdominal approach with the exception that the abdominal contents cannot be examined and access to the right common iliac artery is limited, but extension of aortic exposure superiorly is easier.

●The advantages of the transperitoneal approach to the aorta, which can be via a midline or transverse incision, are ease and familiarity, ready exposure of the pelvic vasculature, and the ability to directly examine the abdominal viscera [48-50]. For transperitoneal incisions, the patient is placed in a supine position with the arms extended or tucked to the patient's sides. When a midline abdominal incision is used, it should be carried from the xiphoid to the pubis to obtain adequate exposure of the aorta proximally to the iliac bifurcation. (See "Incisions for open abdominal surgery", section on 'Midline incision'.)

●A retroperitoneal approach is preferred by many surgeons for the repair of pararenal and suprarenal aneurysms because proximal exposure of the aorta can easily be extended [49-53]. The patient is placed in a right semi-lateral position with the left thorax rotated anteriorly and using a beanbag to maintain the position. For most juxtarenal or infrarenal abdominal aortic aneurysms (AAAs), the retroperitoneal skin incision should start at the tip of the 10^th rib and be carried inferiorly to the lateral border of the rectus muscle just below the level of the anterior superior iliac spine. For suprarenal AAAs, the incision is initiated more proximally in the 8^th intercostal space, which extends the incision into the chest and provides more proximal aortic exposure. (See "Incisions for open abdominal surgery", section on 'Thoracoabdominal'.)

In trials comparing the transperitoneal and retroperitoneal approaches, no significant differences between these approaches have been found for perioperative mortality [54-56]; however, lower rates of postoperative complications (ie, ileus, pneumonia, and incisional hernia) are reported for the retroperitoneal approach [56]. A Cochrane review of four small randomized trials (very low or low quality) comparing retroperitoneal and transperitoneal incisions concluded there was no difference in clamp time, operative time, or mortality [57]. Retroperitoneal incisions may be associated with reduced blood loss and shorter intensive care unit and hospital stays; however, the retroperitoneal approach may increase the risk for postoperative wound complications such as flank hernia and chronic pain. In the era of endovascular surgery, some of the factors discussed below that might have suggested a benefit for one incision over the other are more likely to influence a decision in favor of endovascular aneurysm repair, provided AAA anatomy is suitable [58].

When open repair is elected, the choice of incisional approach is based largely on patient-specific factors such as body habitus and prior abdominal surgery, as well as surgeon experience and preference. As examples:

●Ruptured AAA is usually managed with a midline transperitoneal approach, which allows for expedient aortic clamping, although some experienced surgeons prefer a retroperitoneal approach. (See "Surgical and endovascular repair of ruptured abdominal aortic aneurysm".)

●To avoid intra-abdominal adhesions associated with inflammatory aneurysm, a retroperitoneal approach can be used, but retroperitoneal fibrosis can also create challenges in developing appropriate retroperitoneal planes. Alternatively, a transperitoneal route that approaches the neck of the aorta from the left avoids dissection of the duodenum from the adjacent anterior aortic wall.

●In the patient with obesity, a bilateral transverse upper abdominal incision may be preferred. In some thin patients, a transverse incision limited to the left side of the abdomen may provide adequate exposure of the aorta [59].

●A transabdominal approach may be preferred when managing concomitant right iliac artery aneurysm or stenosis. When a retroperitoneal incision is used, anatomic exposure of the right common iliac artery is difficult, if not impossible, due to the semilateral positioning.

●Depending upon the vascular supply to a horseshoe kidney, a transperitoneal or retroperitoneal incision may be selected [60]. If major arteries emanate from the isthmus of the kidney, a retroperitoneal approach allows for replantation of individual vessels on a Carrel patch. However, if supernumerary vessels originate from the pelvic vasculature, a transperitoneal approach may be preferred, particularly if the vessels arise from the right iliac artery.

●When endovascular repair requires conversion to open repair, more extensive dissection of the aorta is often necessary to obtain aortic control proximal to the level of the endograft, which may have suprarenal fixation with bare stents, hooks, or barbs. Suprarenal or even supraceliac clamping may be needed in this setting. With the increasing use of endovascular aneurysm repair, a greater proportion of open aneurysm repairs will involve complex endograft extraction [61]. Transabdominal or retroperitoneal exposure may be selected based upon the anatomic configuration of the endograft, prior abdominal surgery, the presence and severity of retroperitoneal inflammation, and surgeon experience.

Technique for transperitoneal exposure — To expose the infrarenal aorta using a transperitoneal approach:

●Once the abdomen has been entered, a brief but thorough abdominal exam is recommended to detect any unsuspected, nonvascular pathologies such as concomitant colon cancer, abdominal hernias, and gallstones. An elective AAA repair should usually be aborted if there is significant contamination related to inadvertent entry into the digestive or urinary systems. Acute suppurative conditions such as acute appendicitis, diverticulitis, or cholecystitis should be treated in preference to elective AAA repair. A finding of intra-abdominal malignancy usually supports a decision to defer AAA repair in lieu of further evaluation and treatment.

●The omentum and transverse colon are retracted cranially and the small bowel retracted to the right.

●The peritoneum overlying the infrarenal aorta is incised to the right of the midline to reduce the risk of injury to the inferior mesenteric artery. A self-retaining retractor will facilitate exposure at this point (figure 3).

●The infrarenal aorta is completely exposed from the renal vessels to the aortic bifurcation. Care should be taken to maintain sufficient hemostasis in order to see the important variant vascular structures such as accessory renal arteries or left-sided inferior vena cava.

●Some surgeons prefer to ligate/clip the soft tissue and lymphatic vessels on the anterior surface of the aorta to minimize the risk of lymph leak; however, the incidence of clinically relevant lymph leak is extremely low.

●Excessive dissection along the posterolateral aspect of the aorta is usually unnecessary. Minimizing dissection here avoids the risk of injury to the paired lumbar arteries, large anomalous veins, and/or the sympathetic nerves.

●Circumferential dissection at the neck of the aneurysm should be undertaken cautiously (or not at all) to reduce the risk of injury to retroaortic venous structures. This is particularly important if a retroaortic left renal vein has been identified on preoperative computed tomography (CT) angiography.

Once the aorta has been exposed, the next step is to determine suitable locations for clamp placement. In general, vascular clamps should not be placed in areas of significant thrombus, aneurysm, or calcification. For infrarenal graft placement, normal aortic neck must extend at least one centimeter distal to the position of the infrarenal aortic clamp to allow sufficient space for suture placement. If the aortic neck distal to the renal arteries is insufficient, the suprarenal aorta will need to be exposed to allow the placement of a suprarenal clamp.

To expose the suprarenal aorta for suprarenal clamp placement:

●The left renal vein is mobilized. Small venous tributaries may be ligated and divided to improve exposure of the aorta. It is usually possible to dissect the anterior and lateral surfaces of the aorta while retracting the left renal vein to safely allow the placement of a vertically oriented suprarenal aortic clamp.

●While circumferential control of the infrarenal aorta and placement of a transverse-oriented clamp is preferred by some surgeons, this practice is uncommon for placement of a suprarenal clamp.

●Occasionally it may be necessary to divide the left renal vein to allow safe placement of a suprarenal clamp. The left gonadal vein, the left adrenal vein, and the posterior left lumbar vein should be preserved to assure adequate venous outflow from the left kidney. The Endo GIA stapler with the "white" vascular load may be used to divide the vein. In a review of 261 open AAA repairs, the left renal vein was ligated in 19 percent [62]. There was no significant impact of renal vein ligation on long-term renal function.

●There may be small arterial branches to the adrenal glands and kidneys that arise directly from the aorta and are particularly vulnerable to injury during the suprarenal dissection. These small vessels should be ligated and divided to avoid bothersome bleeding if they are avulsed. Surgical clips are not recommended because they are easily avulsed during subsequent manipulation and clamp placement.

●Excessive traction on the base of the superior mesenteric artery (SMA) should be avoided as this can result in laceration that can be challenging to control. Traction on the SMA can also induce dissection or thrombosis and embolization in the mesenteric circulation.

●The left renal vein can be gently retracted cranially with a vein retractor to allow placement of a vertically oriented aortic clamp that is used to "pin" the aorta from side to side. It should be noted that the left renal vein can be inadvertently avulsed from the vena cava with aggressive traction.

If the aneurysm is confined to the infrarenal aorta, a simple tube graft can be used to replace the aneurysmal aortic segment; however, if the common iliac arteries are aneurysmal (>2 cm), a bifurcated graft should be used. The limbs of the graft can be anastomosed to the common iliac arteries, external iliac arteries, or common femoral arteries depending upon the extent of disease.

To expose the iliac or femoral arteries:

●The ureters should be identified as they cross the iliac arteries at the pelvic brim. The ureters typically cross the distal third of common iliac arteries from lateral to medial. In the presence of iliac aneurysm, the ureter is usually displaced distally toward the iliac bifurcation but may occasionally be encountered more proximally. If injury to the ureter is recognized during dissection but prior to AAA repair, it is usually appropriate to repair the ureter injury and abort the aneurysm repair to reduce the risk of aortic graft infection. (See "Surgical repair of an iatrogenic ureteral injury".)

●Limit the common iliac artery dissection to the anterior and lateral surfaces to reduce the risk of injury to the common iliac veins, which are typically closely applied to the deep surface of common iliac arteries. Iliac vein hemorrhage can be severe and difficult to control. (See 'Preventing and troubleshooting hemorrhage' below.)

●If bypass to the external or internal iliac arteries will be needed, avoid blind, blunt dissection deep in the pelvis to minimize the risk of venous injury. Good retraction, lighting, and careful dissection will prevent potentially catastrophic bleeding.

Technique for retroperitoneal exposure — Once a retroperitoneal incision has been made and the musculature of the abdominal wall has been divided, the retroperitoneal space can be most easily entered toward the posterior aspect of the incision where the posterior peritoneum does not adhere as firmly to the abdominal wall. The peritoneum can be bluntly dissected from the abdominal wall and retracted anteriorly. The kidney can be retracted anteriorly or left in place posteriorly depending on aneurysm morphology. As with the transperitoneal approach described above, the aorta should be initially exposed from the renal vessels to the aortic bifurcation. It should be noted that access to the right common iliac artery is relatively challenging to expose through a left retroperitoneal incision. Division of the inferior mesenteric artery may improve access to the right iliac artery. (See "Incisions for open abdominal surgery", section on 'Thoracoabdominal'.)

ANTICOAGULATION AND REVERSAL — Prior to cross-clamping the aorta during elective abdominal aortic aneurysm (AAA) repair, we administer systemic anticoagulation with unfractionated heparin (50 to 100 IU/kg). We maintain the activated clotting time >200 seconds [63,64]. For patients with a known contraindication to heparin (eg, heparin-associated antibodies), an alternative agent can be used. (See "Management of heparin-induced thrombocytopenia (HIT) during cardiac or vascular surgery" and "Management of heparin-induced thrombocytopenia", section on 'Anticoagulation'.)

Many vascular surgeons feel that systemic anticoagulation during arterial clamping minimizes the risk of arterial thrombosis. This is a common practice, although there is little objective evidence supporting it [65]. The only available trial randomly assigned 284 patients undergoing AAA repair to intravenous heparin or no heparin [66]. No significant differences were reported for median blood loss, volume of blood transfused, or median lower extremity ankle pressures between the two groups. Median ankle pressures were similar before and after AAA repair in both groups. An incidental finding was a lowered overall mortality rate in the heparinized group, predominantly related to a lower rate of myocardial infarction; however, no other trials that have corroborated this effect of heparin on myocardial infarction and death in patients undergoing aortic surgery.

In one small trial, the route of administration (intravenous, direct aortic) and timing (immediately before or after aortic clamping) did not appear to influence the achievement of adequate anticoagulation [67]. A randomized trial (ACTION-1) will evaluate thromboembolic complications for ACT-guided anticoagulation versus fixed dosing during AAA repair [68]

Although we routinely reverse heparin with protamine sulfate after completion of the aneurysm repair and assessment of the extremity circulation, this practice is not universal. Protamine can be associated with adverse hemodynamic and hematologic effects and can cause anaphylaxis in those who have been previously exposed (eg, prior surgery, protamine-containing insulin), and the benefits of protamine with respect to important clinical outcomes have not been demonstrated. Efforts to minimize adverse effects have included reducing the rate of administration and protamine pretreatment prior to systemic anticoagulation [69,70]. (See "Heparin and LMW heparin: Dosing and adverse effects", section on 'Reversal' and "Perioperative anaphylaxis: Clinical manifestations, etiology, and management".)

AORTIC GRAFT PLACEMENT — Aneurysm repair is accomplished by (figure 4) opening the aneurysm after proximal and distal vascular control, removing thrombus and debris from within the aorta, controlling backbleeding from the lumbar arteries, and suturing the graft into the aorta proximally in an end-to-end fashion, and to the aorta distally at the aortic bifurcation for a tube graft, or to the iliac or femoral vessels for a bifurcated graft, whichever is deemed appropriate.

Prior to aortic clamping, the surgeon should take a brief moment to confer with other members of the surgical team. The surgical scrub tech should be prepared to remain in constant attendance throughout the period of aortic clamping. The team should assure that all necessary grafts, clamps, and sutures are immediately available. The anesthesia team should be alerted to the potential hypertensive effect of aortic cross-clamping on arterial blood pressure.

To place the graft:

●Sequentially place the distal and proximal vascular clamps. Some surgeons prefer to place the distal clamps prior to placing the aortic clamp to theoretically reduce the risk of distal embolization, though there is little evidence to support this practice. The proximal aortic clamp can be placed vertically or, if the aorta has been circumferentially dissected, horizontally (not our preference). Incomplete and repetitive clamping should be strictly avoided since this can cause distal embolization.

●Once the clamps have been placed, open the aorta longitudinally with a scalpel or electrocautery, avoiding the origin of the inferior mesenteric artery. Be aware that the intramural segment of the inferior mesenteric artery may exceed one centimeter.

●Bluntly dissect and remove any thrombus or debris from the wall of the aorta. Oversew any backbleeding lumbar vessels. It may be preferable to remove heavily calcified plaque prior to oversewing the lumbar vessels to assure adequate hemostasis.

●Identify the proximal normal margin of aortic tissue distal to the renal arteries and, just distal to it, divide only the anterior half of the aorta (hemi-transection). We prefer to leave the back wall of the aorta intact, but some surgeons completely transect the aorta. Some surgeons position (but do not clamp) a more superiorly placed clamp for rapid aortic control if the infrarenal aortic clamp slips, though it is uncommon for this to happen.

●Suture the graft to the aorta in close proximity to the renal arteries to reduce the potential for late aneurysm formation in the residual infrarenal aortic segment.

●After the proximal anastomosis is completed, place a separate aortic clamp just distal to graft anastomosis and briefly release the infrarenal aortic clamp to test the proximal anastomosis. If bleeding occurs through the suture line, it is prudent to identify the problem and repair it prior to performing the distal anastomosis. Some surgeons further buttress the proximal anastomosis with an additional cuff of graft material placed circumferentially around it.

●Once hemostasis of the proximal anastomosis is assured, pull the graft distally and mark the appropriate length needed. Complete the distal anastomosis at the aortic bifurcation (tube graft) or to the iliac or femoral arteries (bifurcated graft).

●Prior to completing the distal anastomoses, briefly release the proximal clamp to flush the graft from proximal to distal. Then, briefly release the distal clamp(s) to back bleed the distal vessels. If backbleeding is poor, catheter thrombectomy should be performed prior to flow restoration completing the distal anastomosis and restoring flow. (See 'Need for thromboembolectomy' below.)

Suture line bleeding and repair — Suture line bleeding should be meticulously identified and repaired before leaving the operating room. There are four common etiologies of suture line hemorrhage, and each requires a unique treatment. These are as follows:

●Loose suture line – Due to the thickness of the aortic tissue and the use of self-retaining retractors, it is not uncommon for a suture line to be loose. The most common remedy is to use a nerve hook to take up the slack and then tie the loop to an anchoring suture. This can be facilitated by placing a silk suture through the loop of excess suture to serve as a handle while tying. Be sure to check the nerve hook for any sharp burs or edges on a spare suture because it can cut the suture.

●Pleat formation – A pleat occurs when the space between adjacent sutures is excessive. A simple stitch placed at the apex of the pleat will usually stop the bleeding. A pledget is not usually required or beneficial, because it may serve to obscure the source of bleeding.

●Needle hole bleeding from the aorta – If the curve of the needle is not respected while placing a suture, it may cause a longitudinal tear in the aortic wall. This can be repaired by placing a simple transverse-oriented figure-of-eight suture (5-0 polypropylene) in the adventitia adjacent to the needle hole. Avoid the desire to place additional longitudinal sutures across the anastomosis, as this may exacerbate the bleeding.

●Retraction of the adventitia – One of the most serious causes of suture line bleeding is caused by not taking full-thickness bites in the aortic wall. This is particularly common on the posterior aspect of the aortic wall. Failure to pass the needle through the full thickness of the aortic wall will result in an anastomosis that is structurally not sound because the suture is only held in place by aortic plaque. If this problem is identified, the suture line usually needs to taken down and redone, making certain to obtain full-thickness bites.

ABDOMINAL CLOSURE — Prior to abdominal closure, distal perfusion should be assessed by palpating the femoral vessels and pedal vessels or by using a handheld Doppler. The quality of the pulses or Doppler signals should be compared with the preoperative examination. If the distal pulses are diminished by comparison, embolization to the infrainguinal vessels may have occurred and femoral exploration may be indicated. (See 'Need for thromboembolectomy' below.)

Once adequate flow through the graft and distally has been confirmed, the aneurysm sac should be reapproximated using absorbable sutures to cover the graft and prevent abrasion of the overlying bowel that could lead to aortoenteric fistula formation. (See 'Graft infection' below.)

Following open AAA repair, the midline abdominal incision is typically closed primarily. However, incorporating mesh may help reduce the incidence of incisional hernia [71-74]. While we do not routinely incorporate mesh into abdominal wall closure following open AAA repair, based upon randomized trials, mesh can be considered in patients with additional risk factors for incisional hernia such as obesity or connective tissue disorders. In one early trial of abdominal wall closure after AAA repair, postoperative incisional hernia developed in 16/45 patients in the control group compared with 5/40 in the mesh group (hazard ratio 4.10, 95% CI 1.72-9.82) [71]. Hernias developed between 170 and 585 days after surgery in the control group, and between 336 and 1122 days in the mesh group. A later review identified four trials with a total of 388 patients [74]. Mesh reinforcement significantly reduced the risk of incisional hernia after AAA repair compared with standard sutured closure (pooled risk ratio [RR] 0.27, 95% CI 0.11-0.66). However, the pooled rate of reoperation was no different between groups. Mesh reinforcement also did not cause more intraoperative or postoperative complications compared with sutured closure. (See "Principles of abdominal wall closure", section on 'Prophylactic mesh' and "Clinical features, diagnosis, and prevention of incisional hernias", section on 'Prevention'.)

OTHER TECHNICAL CONSIDERATIONS

Handling the inferior mesenteric artery — Colonic ischemia is uncommon following elective abdominal aortic aneurysm (AAA) repair [75,76]. The adequacy of perfusion to the left colon should always be assessed prior to completion of the case, and the inferior mesenteric artery should be reimplanted if there is any question of bowel viability.

In general, if backbleeding from the orifice of the inferior mesenteric artery (IMA) within the aneurysm sac is vigorous, indicating adequate collateral flow, or the vessel is occluded (no backbleeding), reimplantation of the IMA into the aortic graft is not necessary [77-79]. In one trial, patients with a confirmed patent IMA were randomly assigned to replantation or ligation [80]. There was no significant difference in the incidence of ischemic colitis between the groups (replanted: 6 patients, ligated: 10 patients). However, in patients with prior colon resection or reduced inflow to one or both internal iliac arteries, reimplantation of the inferior mesenteric artery is appropriate.

Need for thromboembolectomy — All aortic aneurysms have some degree of mural thrombus and cholesterol plaque, which have the potential to dislodge and embolize during the course of aortic dissection and clamping. However, thromboembolism is uncommon with elective AAA repair. Nevertheless, diminished backbleeding from the iliac vessels (or femoral arteries) should prompt Fogarty catheter embolectomy.

Once the graft has been placed and the vascular clamps have been removed, the femoral pulses should be palpable. If the femoral pulses cannot be palpated, the cause must be determined. It is important to ensure that any self-retaining retractors have been release or removed, as these can compress the external iliac arteries and give the errant impression of arterial obstruction. After reapplying a clamp on the proximal graft, opening the distal anastomosis is usually the most appropriate initial step, allowing inspection to of the anastomosis for technical defects and passage of a Fogarty balloon catheter distally into the lower extremity vessels.

Sometimes occlusive disease or excessive tortuosity of the iliac arteries prevents effective passage of the Fogarty catheter. In this case, the common femoral artery should be exposed and a femoral embolectomy performed. If unimpeded inflow can be established, the femoral arteriotomy can be closed primarily; however, if inflow cannot be established, then the aortic graft can be extended to the femoral level. (See "Embolism to the lower extremities", section on 'Open embolectomy'.)

Handling the internal iliac arteries — Pelvic arterial inflow is supplied predominately by branches of the inferior mesenteric artery and the bilateral internal iliac arteries (figure 5). Arterial inflow should be preserved to at least one of these vessels. It is always prudent to assess the viability of the colon at the completion of all aortic procedures. Reimplantation of the inferior mesenteric artery may reduce the risk of colon ischemia in selected cases. (See 'Handling the inferior mesenteric artery' above.)

In the absence of prior colon surgery, it is usually safe to ligate the inferior mesenteric artery provided at least one of the internal iliac arteries remains patent. In rare cases, it may be necessary to ligate one or both internal iliac arteries. This occurs most commonly due to extensive aneurysmal involvement of the internal iliac artery deep into the pelvis that precludes arterial reconstruction. In this setting, the inferior mesenteric artery should usually be replanted to reduce the risk of colonic and/or pelvic ischemia. (See "Colonic ischemia", section on 'Risk factors'.)

Preventing and troubleshooting hemorrhage — Significant bleeding can complicate AAA repair as a result of gaps in the anastomosis, suture holes (particularly if a polytetrafluoroethylene graft is used), coagulation abnormalities and bleeding from raw surfaces, and inadvertent venous injury (inferior vena cava, renal vein, common iliac vein).

Troublesome bleeding from the proximal aortic anastomosis may require transecting the aorta to buttress the anastomosis or to obtain adequate exposure to place additional sutures.

Intraoperative bleeding through needle holes or the raw retroperitoneal surfaces can be managed using topical hemostatic agents, which can help minimize ongoing blood loss, provided there is no bleeding that requires direct suture repair. Preliminary studies using recombinant factor VIIa suggest a potential role in controlling intractable perioperative bleeding in aortic surgery patients [81]. (See "Overview of topical hemostatic agents and tissue adhesives".)

Inadvertent injury of the common iliac veins can lead to significant hemorrhage. Venous bleeding can usually be controlled with packing, but occasionally it may be necessary to transect the overlying iliac artery to expose the venous injury to allow suture repair.

POSTOPERATIVE CARE — Following open abdominal aortic aneurysm (AAA) repair, the patient is transferred to a monitored setting. The postoperative course is highly variable depending upon the extent of the procedure and comorbidities of the patient.

For uncomplicated infrarenal repairs, the endotracheal tube and nasogastric tube can be removed in the recovery room. A clear diet can be initiated on the first postoperative day and advanced as tolerated. Early ambulation, appropriate opioid-sparing pain control, and respiratory care will help prevent postoperative pulmonary complications [42]. (See "Approach to the management of acute pain in adults" and "Strategies to reduce postoperative pulmonary complications in adults", section on 'Postoperative strategies'.)

Pharmacologic thromboprophylaxis can be resumed 18 to 24 hours after surgery, provided there is no concern for bleeding. Mechanical prophylaxis (thigh-high sequential compression) should be maintained until the patient is ambulatory.

FOLLOW-UP — Following discharge, the patient should follow up to remove any sutures or staples remaining in the abdominal wall, evaluate the incision for possible incisional hernia, and reassess arterial pulses and perfusion. (See 'Incisional hernia' below.)

Thereafter, additional follow-up is dictated by the development of any symptoms (eg, claudication) that might indicate problems with the graft limb anastomoses. Issues related to the proximal aortic anastomosis are uncommon; however, late pseudoaneurysm can occur, and dilation of the proximal aorta has been reported, particularly if the graft was placed too inferiorly [82,83]. Thus, we routinely obtain computed tomography five years following the open repair to assess the aorta for the late aortic dilation or pseudoaneurysm. (See 'Anastomotic aneurysm' below.)

MORBIDITY AND MORTALITY — Perioperative (30-day) mortality for elective open abdominal aortic aneurysm (AAA) repair in contemporary series is between 1 and 5 percent [84-89]. A review of the Vascular Quality Initiative database from 2003 to 2019 reported that 97.1 percent of patients undergoing open AAA repair were alive at hospital discharge [90]. The cause of perioperative death for most patients is multisystem organ failure.

The presence of peripheral artery disease increases the risk of perioperative morbidity and mortality. After risk adjustment, when compared with males without PAD, males with PAD undergoing AAA repair had almost three times the odds of 30-day mortality (odds ratio [OR] 2.77, 95% CI 1.42-5.40) [15]. Similarly, compared with females without PAD, females with PAD undergoing AAA repair had nearly four times the odds of 30-day mortality (odds ratio [OR] 3.86, 95% CI 1.55-9.64).

For patients who survive open AAA repair, the main cause of death in the long-term is cardiovascular disease. In a study that evaluated 297 patients following open infrarenal/juxtarenal AAA repair, cardiovascular events occurred at a rate of 0.16 cardiovascular events/patient-year [91]. Freedom from cardiovascular events at 1, 5, 10, and 15 years was 94, 67, 46, and 28 percent, respectively. Survival was 97, 75, 51, and 32 percent, respectively. The main cause of death was cardiovascular disease (18.2 percent), followed by cancer (14.5 percent). Only four (1.3 percent) deaths were graft related.

In patients with complex aneurysms, defined as short neck, juxtarenal, pararenal, and suprarenal AAAs, open AAA repair compared with endovascular repair was associated with improved long-term survival without any increase in perioperative death [28].

Complications following open AAA repair are similar to those of other major surgical procedures and are most often related to preexisting medical conditions. Complications include heart failure, myocardial ischemia, acute kidney injury, pulmonary insufficiency, and pneumonia. Management of these complications can be found in separate topic reviews. A thorough preoperative evaluation and proper patient selection help to reduce the incidence of these complications. (See "Management of asymptomatic abdominal aortic aneurysm", section on 'Medical risk assessment'.)

Perioperative complications related to the aortic procedure include lower extremity ischemia, bowel ischemia, pelvic ischemia, and renal dysfunction, and late complications include incisional hernia, anastomotic aneurysm, and graft infection/aortoenteric fistula. Late complications of open surgical aneurysm repair were identified in 9.5 percent of patients in one retrospective review [92]. The mean time between aortic repairs was 11 years. When compared with 993 other patients for whom endovascular repair was the primary aortic repair, late complications following primary open AAA repair occurred in patients who were significantly younger at the time of their first repair (61 versus 74 years), and more patients had a family history of aneurysm (20 versus 7 percent).

Lower extremity ischemia — Lower extremity ischemia may occur as a result of arterial occlusion due to clamp injury, arterial wall dissection, or thrombosis or thromboembolism distally. The clinical manifestations and diagnosis of aortic thromboembolism are discussed elsewhere. (See "Thromboembolism from aortic plaque".)

Measures to reduce the risk of lower extremity ischemia during open AAA repair include minimizing aortic and iliac artery dissection to the regions that will be clamped, avoiding clamping through thrombus or heavily calcified regions, routinely flushing and irrigating the vessel lumen prior to closure, and assessing femoral and distal extremity pulses prior to leaving the operating room.

Renal dysfunction — Renal dysfunction can result from embolism of debris into the renal arteries or as a result of decreased renal blood flow during the course of mobilizing and clamping the aorta. The incidence of renal dysfunction is greater with suprarenal compared with infrarenal AAA repair [93,94]; however, even infrarenal clamping can reduce renal blood flow up to 60 percent of normal. In a retrospective review of 2347 patients, renal failure occurred in 140 patients (6 percent) [95]. Risk factors for postoperative renal failure included age >75, symptomatic AAA, supra/juxtarenal AAA, elevated preoperative serum creatinine, treated hypertension, and respiratory disease. Recognition and prompt management of abdominal compartment syndrome may also reduce the incidence of significant postoperative renal dysfunction. Patients with postoperative renal failure had significantly higher 30-day mortality (35.0 versus 4.3 percent).

Bowel ischemia — Bowel ischemia can affect the small or large intestine. Acute mesenteric ischemia is rare with infrarenal AAA repair. Colonic ischemia is more likely to occur following open repair of ruptured AAA, for which the incidence is between 7 and 27 percent compared with 0.6 to 13 percent for elective AAA repair [96]. The incidence varies greatly depending upon the diagnostic algorithm to detect it [97]. When bowel ischemia complicates AAA repair, mortality is increased. (See "Overview of intestinal ischemia in adults" and "Colonic ischemia".)

The majority of patients do not have symptoms, and only 30 percent have bloody diarrhea. Patients suspected of postoperative colon ischemia should undergo immediate sigmoidoscopy to assess the viability of the colonic mucosa. Patients with full-thickness ischemia are treated with colon resection. For partial-thickness ischemia, most surgeons recommend bowel rest, antibiotics to cover typical colon flora, and repeat sigmoidoscopy in one to two days to assess resolution or identify progression. It may occasionally be appropriate to consider late reimplantation of the inferior mesenteric artery (IMA) for partial-thickness bowel ischemia that does not mandate resection. The diagnosis and management of colon ischemia is discussed elsewhere.

Incisional hernia — Incisional hernia is common following open AAA repair, likely due to a global problem with connective tissue integrity that is responsible for aneurysm formation. Increasing body mass index and length of the incision are risk factors for the development of incisional hernia [98]. The diagnosis and management of incisional hernia are discussed in detail elsewhere. (See "Overview of abdominal wall hernias in adults", section on 'Ventral incisional hernia'.)

Sexual dysfunction — The incidence of sexual dysfunction prior to abdominal aortic surgery varies in the reported literature but is generally quite high [17,99-101]. Aortic dissection in the region of the pelvic nerves can exacerbate existing dysfunction or lead to new complaints. In the DREAM trial, the proportion of patients with sexual dysfunction (in at least one aspect as defined in the trial) was 66 percent, increasing to 79 percent postoperatively [17]. The magnitude of sexual dysfunction was more pronounced for open surgery compared with endovascular repair at three and six weeks follow-up, but from three months onward, both groups had returned to baseline status.

Graft infection — Aortic graft infection is rare, occurring in approximately 0.3 percent of patients undergoing open AAA repair. Extension of the graft into the femoral region increases the incidence to as much as 3 percent, with an associated mortality as high as 50 percent. (See "Overview of infected (mycotic) arterial aneurysm".)

Aortic graft infection may be the cause or consequence of aortoenteric fistula, which is related to erosion of the proximal aortic graft into the small bowel, usually the third portion of the duodenum. (See "Aortoenteric fistula: Recognition and management" and "Causes of upper gastrointestinal bleeding in adults", section on 'Aortoenteric fistulas'.)

Treatment of an infected aortic graft generally requires removal of infected graft material. Blood flow to the lower extremities is provided by extraanatomic reconstruction (axillofemoral bypass) or in-situ reconstruction with autogenous vein (femoral vein), but antibiotic impregnated grafts, cryopreserved arterial conduits, and endovascular grafting have also been used. The use of prosthetic material is associated with a reinfection rate of 25 percent.

Anastomotic aneurysm — Anastomotic aneurysms can be true aneurysms due to ongoing degeneration of the aortic wall or false aneurysms (ie, pseudoaneurysms) from disruption of the suture repair between the native aorta and prosthetic material. Anastomotic aneurysm can occur proximally or distally. Proximal anastomotic aneurysms have a propensity to develop when the proximal aortic anastomosis is placed too far inferior to the renal arteries. When anastomotic aneurysms occur at the site of a femoral anastomosis, they are frequently associated with infection.

Anastomotic aneurysms traditionally required re-do surgery for repair; however, relining the original surgical repair with an endograft is an alternative, provided it is anatomically feasible and graft infection has been ruled out.

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Aortic and other peripheral aneurysms".)

SUMMARY AND RECOMMENDATIONS

●Abdominal aortic aneurysm – An aortic diameter greater than 3.0 cm is considered aneurysmal for most adults. The indications for repair of abdominal aortic aneurysm (AAA) include symptomatic aneurysm of any size (eg, abdominal, back or flank pain, evidence of embolization, frank rupture), asymptomatic aneurysm ≥5.5 cm, rapidly expanding AAA, AAA associated with other arterial disease, infected AAA, and complications following endovascular repair necessitating early or late conversion to an open AAA repair. Open repair of abdominal aortic aneurysm is contraindicated in patients with a prohibitive operative risk. Relative contraindications to open surgical repair of AAA in the era of endovascular aneurysm repair may include hostile abdomen, obesity, and limited life expectancy. (See 'Indications for open repair' above and "Management of asymptomatic abdominal aortic aneurysm", section on 'Summary of indications for elective AAA repair' and "Management of symptomatic (non-ruptured) and ruptured abdominal aortic aneurysm", section on 'Approach to AAA associated with symptoms' and "Endovascular repair of abdominal aortic aneurysm".)

●Risk assessment – In preparation for open abdominal AAA repair, patients should undergo medical risk assessment, including preoperative consultation with the anesthesia team. Recommendations for management of cardiac risk, including pharmacologic therapies for secondary prevention of cardiovascular events (ie, antiplatelet therapy, beta blocker therapy, statin therapy), are discussed separately. (See "Anesthesia for open abdominal aortic surgery" and "Management of cardiac risk for noncardiac surgery", section on 'Summary and recommendations'.)

●Vascular evaluation – The preoperative vascular evaluation should focus on the identification of coexistent aneurysms (eg, iliac aneurysm, popliteal aneurysm) and/or occlusive disease. For patients who present with lower extremity symptoms such as claudication, noninvasive vascular studies should be performed. The preoperative sexual health of the patient should also be documented. Computed tomographic (CT) angiography should be performed to evaluate the anatomy, extent (eg, infrarenal, suprarenal), and features (eg, extent of thrombus, calcification, inflammation) of the aneurysm, and to identify anatomic abnormalities (eg, retrocaval left renal vein, accessory renal arteries, horseshoe kidney, inflammatory aneurysm) that may alter the approach to repair. (See 'Vascular evaluation' above and 'Aortic imaging' above.)

●Antimicrobial prophylaxis – Prior to AAA repair, prophylactic antibiotics are recommended. Appropriate antibiotic options are given in the table (table 2). For patients undergoing treatment of infected aneurysm, the choice of antibiotics will depend upon blood culture and sensitivity results. For patients who have been started on antibiotics due to concerns for infection, antibiotics should be re-dosed prior to surgery. (See 'Prophylactic antibiotics' above and "Antimicrobial prophylaxis for prevention of surgical site infection in adults", section on 'Antimicrobial prophylaxis'.)

●Thromboprophylaxis – Thromboprophylaxis should be administered according the patient's risk for thromboembolism (table 3). The administration of intraoperative heparin should not be misconstrued as an appropriate substitute for recommended prophylactic strategies. However, we omit pharmacologic thromboprophylaxis for patients with ruptured AAA or impending rupture. We prefer using unfractionated heparin or, alternatively, low-molecular-weight heparin (LMWH), rather than fondaparinux for pharmacologic prophylaxis given the potential need for reversal if there are bleeding problems during the surgery. We also use intermittent pneumatic compression (IPC), rather than no compression, whenever possible. (See 'Thromboprophylaxis' above and "Prevention of venous thromboembolic disease in adult nonorthopedic surgical patients", section on 'Selecting thromboprophylaxis'.)

●Bowel preparation – We suggest not routinely administering mechanical or antibiotic bowel preparation prior to elective, open AAA repair (Grade 2B). Advocates suggest that bowel preparation reduces the risk of bowel ischemia and may reduce the time to resuming oral intake, and although this continues to be the practice of many surgeons, there is little objective evidence that bowel preparation is beneficial prior to open AAA repair. In addition to being unpleasant for the patient, bowel preparation can be associated with volume and electrolyte depletion. (See 'Bowel preparation' above.)

●Approach and techniques

•Incisional approach – The abdominal aorta can be exposed through a midline transperitoneal or retroperitoneal approach. A retroperitoneal approach allows full exposure of the abdominal aorta in much the same fashion as the transabdominal approach, with the exception that the abdominal contents cannot be examined and access to the right common iliac artery is limited, but extension of aortic exposure superiorly is easier. The choice of approach is based largely on the clinical situation or the patient's anatomy, as well as patient preference and the surgeon's experience and preference. In the era of endovascular surgery, some of the factors that might have suggested a benefit of one incision over the other are more likely to influence a decision in favor of endovascular aneurysm repair, provided AAA anatomy is suitable. (See 'Incision and aortic exposure' above.)

•Aortic repair – Aortic aneurysm repair (figure 4) is carried out in a systematic fashion. After aortic exposure and clamping, the graft is sutured into the proximal aorta and sutured distally at the aortic bifurcation or to the iliac or femoral vessels, whichever is deemed appropriate. Graft options for aortic replacement include polyester (eg, Dacron), polytetrafluoroethylene, and autogenous vein. (See 'Aortic graft placement' above.)

•Systemic anticoagulation – We suggest systemic anticoagulation, typically accomplished with unfractionated heparin (50 to 100 IU/kg), prior to cross-clamping the aorta during elective AAA repair (Grade 2C). We maintain the activated clotting time >200 seconds. Although we generally reverse heparin with protamine sulfate after completion of the aneurysm repair and assessment of the extremity circulation, heparin reversal with protamine has never been shown to be of benefit, and there are potential serious side effects. (See 'Anticoagulation and reversal' above.)

•Preventing thromboembolism – All aortic aneurysms have some degree of mural thrombus and cholesterol plaque, which have the potential to dislodge and embolize during the course of aortic dissection and clamping. However, thromboembolism is uncommon with elective AAA repair. Prior to closure, distal perfusion should be assessed by palpating the femoral vessel and pedal vessels or by using a handheld Doppler. The quality of the pulses or Doppler signals should be compared with the preoperative examination. If the pulses are diminished, embolectomy should be performed. (See 'Need for thromboembolectomy' above.)

•Preserving pelvic inflow – Colonic ischemia is uncommon following elective AAA repair. Pelvic arterial inflow should be preserved to at least one vessel (inferior mesenteric artery, right internal iliac artery, left internal iliac artery). Reimplantation of the inferior mesenteric artery may reduce the risk of colon ischemia in selected patients, particularly those with prior colon resection or reduced inflow to one or both internal iliac arteries. (See 'Handling the inferior mesenteric artery' above and 'Handling the internal iliac arteries' above.)

●Morbidity and mortality – Perioperative (30-day) mortality for elective open AAA repair in contemporary series is between 1 and 5 percent. Perioperative morbidity and mortality are increased in patients with advanced age; female sex; or cardiac, pulmonary, or kidney disease. The cause of death for most patients is multisystem organ failure. For patients who survive open AAA repair, the main cause of death in the long term is cardiovascular disease. Perioperative complications related to the aortic procedure include lower extremity ischemia, bowel ischemia, pelvic ischemia, and renal dysfunction, and late complications include incisional hernia, anastomotic aneurysm, and graft infection/aortoenteric fistula. (See 'Morbidity and mortality' above.)