Left colectomy: Open technique

INTRODUCTION — A left hemicolectomy includes resection of the transverse colon left of the middle colic vessels to the level of the upper rectum. A segmental left colectomy is performed when lesser resections are indicated (eg, trauma, polyp), provided the anastomosis is performed in well-vascularized bowel.

The open techniques used to perform left colectomy are reviewed here.

Right and extended right colectomy are presented separately. (See "Right and extended right colectomy: Open technique".)

Minimally invasive (laparoscopic and robotic) techniques of left/sigmoid colectomy are discussed in another topic. (See "Minimally invasive techniques: Left/sigmoid colectomy and proctectomy".)

COLON ANATOMY — The colon and rectum occupy the retroperitoneal and intraperitoneal spaces, in close approximation to solid organs (figure 1). The ascending and descending colon are retroperitoneal, while the transverse colon, which extends from the hepatic flexure to the splenic flexure, is intraperitoneal. The sigmoid colon continues from the descending colon, ending where the teniae converge to form the rectum.

Arterial supply — The arterial supply of the left colon has few profuse anastomoses and collateral circulations. The middle colic artery (MCA) and the inferior mesenteric artery (IMA) provide the principle blood supply to the left colon (figure 2). The marginal artery of Drummond and the arc of Riolan provide collateral blood vessels. Typically, the blood supply of the transverse colon is excellent provided the marginal artery is not damaged. Variability in the arterial anastomoses occurs, which is an important point when performing a segmental resection. The two most tenuous sites and the corresponding arterial supplies are the splenic flexure (Griffith's point) and distal descending colon (Sudeck's point). (See "Overview of intestinal ischemia in adults", section on 'Intestinal vascular anatomy'.)

Venous and lymphatic drainage — The venous drainage of the left colon is through the inferior mesenteric vein (figure 3). The lymphatic drainage flows along the left colic artery and the sigmoid vessels to the inferior mesenteric vessels (figure 4).

PREOPERATIVE EVALUATION AND PREPARATION — General issues regarding the medical preparation of patients, including antibiotic prophylaxis, bowel preparation, and other considerations, such as anticipated splenectomy, prior to colon resection are reviewed separately. Siting for possible ostomy locations should be performed prior to surgery. (See "Overview of colon resection", section on 'Preoperative evaluation' and "Overview of surgical ostomy for fecal diversion", section on 'Site selection and marking'.)

It is helpful to have a flexible colonoscope available in the operating room as it may be needed to identify a cancer or other mucosal lesion if it cannot be palpated.

We prefer that the patient be placed in lithotomy position, though the procedure can also be performed supine. Lithotomy allows simultaneous access to the abdomen and perineum for the colorectal anastomosis when using the circular stapler, as well as for intraoperative colonoscopy or proctoscopy. It also provides additional space for the second assistant and an additional position for the operating surgeon when mobilizing the splenic flexure.

INDICATIONS — The indications for a left hemicolectomy include benign conditions (eg, segmental Crohn's colitis, trauma, ischemia, polyps unresectable through a colonoscope) and malignant diseases (eg, distal transverse colon cancer, mid-descending colon cancers). Diverticular disease, typically treated with a sigmoid colon resection, may require a left hemicolectomy if the descending colon is unsuitable for an anastomosis due to active diverticulitis or muscular hypertrophy. (See "Overview of colon resection", section on 'Indications for colon resection'.)

ABDOMINAL EXPLORATION — Prior to proceeding with colon resection, the abdomen should be systematically explored. The anatomy of the colon and its blood supply should be verified, noting any anatomic variations or possibly any congenital anomalies (eg, malrotation). For patients with abdominal trauma, the abdomen is packed and systematically examined, removing the packs in turn. Bleeding is controlled first followed by control of gastrointestinal leakage. (See "Traumatic gastrointestinal injury in the adult patient", section on 'Abdominal exploration'.)

For patients with colon tumors, the primary tumor is palpated to confirm its location. Local and regional resectability is determined by assessing tumor invasion into the stomach, major vessels, and/or duodenum (figure 1). The entire colon should also be palpated to identify synchronous colonic lesions. Abdominal exploration also includes an assessment for distant disease, including peritoneal implants, hepatic metastases, or distant nodal metastases.

EXTENT OF RESECTION — The extent of surgery is based upon the location of the lesion, disease process (benign versus malignant), blood supply, and venous and lymphatic drainage of the colon. (See "Overview of colon resection", section on 'Benign versus malignant disease'.)

Colon — Benign lesions may be resected with a hemicolectomy or a segmental resection. As an example, extensive benign lesions of the left colon (eg, inflammatory bowel disease, diverticular disease) can be removed with a less extensive colon resection than is required for a cancer operation, providing the anastomosis is performed in well-vascularized bowel (figure 5). For well-defined benign conditions of the left colon (eg, trauma, diverticular disease, inflammatory bowel disease), a segmental resection with a primary anastomosis in well-vascularized colon and a limited mesenteric resection can be performed (figure 6). Resection margins must be chosen to ensure adequate blood supply in the remaining colon. For large polyps that require a surgical resection because of a possible malignancy, the authors perform a formal cancer operation.

Malignant lesions of the left colon are typically resected with a left hemicolectomy, extending from the distal transverse colon to the upper rectum, 2 to 3 cm above the sacral promontory (figure 7). For malignant lesions of the splenic flexure, a limited resection extending from the transverse to the sigmoid colon can be performed, but the pedicle of the left colic artery and the first sigmoid branch must be included (figure 8). The proximal and distal colon segments are divided with a minimum of a 5 cm margin of normal colon. The anastomosis is intraperitoneal between well-vascularized colon segments; the presacral plane posterior to the rectum is not entered.

In the uncommon setting of the detection of an unsuspected synchronous colonic cancer, we perform a subtotal colectomy to remove both lesions, including adequate resection margins with high ligation of mesenteric vessels and complete nodal harvest. Surgical management of synchronous metastatic disease (stage IV) is reviewed separately. (See "Surgical resection of primary colon cancer", section on 'Synchronous colon cancer' and "Locoregional methods for management and palliation in patients who present with stage IV colorectal cancer".)

Mesentery — The extent of the mesenteric resection also varies according to the indication for surgery. As an example, when performing the resection for malignant lesions, the inferior mesenteric artery is ligated at its origin from the aorta, the inferior mesenteric vein is ligated at the level of the pancreas, and the mesentery and draining lymphatics are removed with the vascular pedicle. (See "Overview of colon resection", section on 'Benign versus malignant disease'.)

A less extensive resection of the mesentery is performed for benign conditions, with the mesenteric vessels ligated closer to the colon (figure 9). However, for settings of severe mesenteric inflammation (eg, diverticulitis, inflammatory bowel disease) and thickening of the mesentery near the bowel wall, mesenteric dissection may be warranted.

Omentum — The omentum is divided from the transverse colon for most resections. However, when the omentum is involved with a left transverse colon cancer, it must be resected en bloc. The omentum is divided between the colon and the gastroepiploic arcade along the greater curvature of the stomach, tying off the epiploic branches (figure 10).

MOBILIZING THE LEFT COLON — There are two approaches to resecting the left colon; one begins laterally by mobilizing the colon and progresses medially, while the other begins medially by identifying the lymphovascular bundle and progresses laterally. The approach is at the discretion of the surgeon, although in most settings the lateral-to-medial approach is performed.

Lateral-to-medial approach — The lateral-to-medial approach begins by mobilizing the left colon by dividing the lateral peritoneal attachment of the colon and developing the retromesenteric plane. This approach provides early identification and exposure of the ureter and gonadal vessels (figure 11 and figure 12 and figure 13 and figure 14) and can be used to resect malignant and benign diseases of the left colon.

The general principles for performing a left hemicolectomy, beginning with mobilizing the left colon, include:

●Retract the small bowel medially to expose the left colon.

●Retract the left colon medially and incise the peritoneal attachments in the left paracolic gutter just medial to the line of Toldt (figure 15) at the level of the sigmoid colon. A bloodless plane is entered as the mesocolon is lifted away from the investing retroperitoneal fascia, which is left intact.

●Identify and avoid injury to the left ureter and gonadal vessels in the retroperitoneum. If the ureter cannot be seen, the dissection plane may be too deep. Check medially under the reflected peritoneum as the ureter may have been lifted anteriorly with the investing retroperitoneal fascia.

●Incise the peritoneum to the level of the splenic flexure. The peritoneal incision now follows the curve of the colon, remains inferomedial to the spleen, and continues around the corner of the flexure. Divide splenocolic ligaments with scissors or electrocautery to prevent tearing the splenic capsule. An alternative approach for patients with a thick mesentery or in settings where it is technically difficult to mobilize the splenic flexure is to approach the splenic flexure medially from the midtransverse colon and the dissection continued laterally (figure 16). For patients with a high splenic flexure, the optimal approach is to mobilize the apex stepwise, alternating the mobilization from the distal transverse colon and proximal descending colon.

●Rotate the left colon medially to identify the renocolic ligament and divide with scissors or electrocautery to release the mesocolon from Gerota's fascia (figure 17). Elevating the ligaments over an index finger can facilitate the dissection. Small bleeding points can be cauterized or ligated.

●Lift the omentum and left transverse colon to create tension on their fusion plane (figure 18A-C). Use electrocautery to divide the omentum from the epiploica and the superior leaf of the transverse mesocolon. This maneuver permits entry into the lesser sac behind the stomach. Dissect medially, separating the omentum from the colon to the middle colic vessels. There should be minimal bleeding when the dissection is performed in the correct plane. Avoid placing the mesocolon under tension by dissecting the reflected edge of the mesocolon as it is lifted off the retroperitoneum.

●Continue mobilizing the left colon until it is completely free from its retroperitoneal attachments and suspended entirely on its mesentery near the midline.

●Incise the medial aspect of the mesocolon from the level of the duodenum to the sacral promontory.

●Identify and clear the inferior mesenteric artery (IMA) of local tissue at its origin from the aorta without injuring the preaortic sympathetic nerves. Doubly ligate the IMA with an absorbable (eg, 0 or 2-0 polyglycolic or polyglactin) or nonabsorbable suture (eg, 0 or 2-0 silk), depending on the surgeon's discretion.

●Identify and clear the inferior mesenteric vein (IMV) of local tissue as it passes behind the duodenal jejunal junction. Doubly ligate the IMV with an absorbable or nonabsorbable suture as done for the IMA.

●Divide the mesentery with an electrosurgical or alternative energy device (eg, LigaSure, Harmonic scalpel) or sharply divide and ligate with suture ties, depending on the surgeon's preference and availability of equipment. Advanced electrosurgical devices are faster and can seal vessels up to 7 mm in diameter, including the pedicles, but are more costly. Avoid tension to ensure a complete vessel seal. (See "Overview of electrosurgery", section on 'Advanced electrosurgical devices' and "Overview of electrosurgery", section on 'Alternative energy sources'.)

●Score the mesorectum with electrocautery, clamp and divide the tissue perpendicular to the axis of the bowel between clamps, and secure with 2-0 absorbable suture. Alternatives to the clamp and divide technique include the pinch-burn technique (grasp tissue with forceps and apply electrocautery until vessels are sealed and tissue divided), LigaSure technique, and harmonic scalpel. The mesocolon of the proximal bowel is prepared in a similar fashion.

●Divide the proximal and distal bowel between two noncrushing bowel clamps (eg, Doyen intestinal clamp (picture 1)) if performing a hand-sewn anastomosis or between a transverse bowel clamp and linear stapler if performing a stapled anastomosis. The remaining colon must be well vascularized, pulses must be palpated in the last arcade, and the cut bowel edges must bleed.

Medial-to-lateral approach — The medial-to-lateral approach is ideal when a tumor is large and/or adherent to the lateral side wall. The advantage of the medial approach includes early ligation of the lymphovascular pedicle, which lessens the risk of injury as a result of torsion during colon mobilization. Early vascular ligation also allows demarcation between ischemic and well-perfused bowel prior to transecting the bowel and more efficient identification of the resection plane in the setting of severe mesenteric inflammation (eg, diverticulitis, inflammatory bowel disease).

The general principles for performing a left hemicolectomy, beginning with the ligation of the inferior mesenteric vessels, include:

●Expose the root of the mesenteric vessels by lifting the small bowel medially and superiorly.

●Incise the peritoneum 1 to 2 cm distal to the origin of the IMA while placing the sigmoid and descending colon under gentle tension (figure 19). Extend the peritoneal incision along the sulcus to the sacral promontory. A dissection plane between the retroperitoneum and the mesocolon is developed moving medial to lateral and posterior to the inferior mesenteric artery. The retroperitoneal investing fascia remains intact.

●Identify the ureter and gonadal vessels and sweep structures posteriorly.

●Continue the dissection laterally behind the mesocolon and colon until the lateral peritoneum is the only remaining structure.

●Identify and ligate the IMA and IMV as described above. (See 'Lateral-to-medial approach' above.)

●Develop the dissection plane superiorly and posterior to the mesocolon, splenic flexure, and left transverse colon. The posterior attachments are divided with electrocautery or scissors.

●Retract the colon medially and incise the lateral peritoneum beginning at the level of the rectosigmoid colon and extending the incision to the splenic flexure. This dissection plane should meet the plane developed medially between the retroperitoneum and mesocolon.

●Divide the transverse colon from the omentum, resect the mesentery, and transect the bowel as described above.

COLOCOLONIC ANASTOMOSIS — Options for restoring bowel continuity include an end-to-end or side-to-end colorectal or colocolic anastomosis, which can be either performed with a stapling device or hand-sewn. An alternative anastomosis that can be used between the proximal and distal colon (not rectum) is the functional end-to-end anastomosis, which is technically a side-to-side approach. There is insufficient evidence that any one configuration is better functionally or less likely to leak or that a stapled colorectal anastomosis is superior to a hand-sewn one [1]. The decision is based upon surgeon experience, preference, and available equipment. (See "Right and extended right colectomy: Open technique", section on 'Ileocolonic anastomosis'.)

Hand-sewn anastomosis — A single-layer hand-sewn closure with absorbable (eg, polyglycolic acid) suture or nonabsorbable (eg, silk, polypropylene) suture is used to create a hand-sewn anastomosis. There is no evidence that a two-layer closure is preferable to a single-layer closure [2,3]. While two-layer closures were routinely performed in the past, a randomized trial of 132 patients undergoing an intestinal anastomosis found that the single-layer closure was associated with similar complication rates for anastomotic leaks (two [3.0 percent] versus one patient [1.5 percent]) and intra-abdominal abscesses (two patients each) compared with a two-layer closure [4]. However, the cost of materials and time to sew the anastomosis was significantly less for the single-layer anastomosis.

There is no evidence of superiority of one type of suture material compared with another in anastomoses [5]. We prefer to use absorbable polyglycolic acid suture for its handling characteristics as well as for its absorption at an appropriate rate. Polyglycolic acid suture retains approximately 60 percent of its strength at day 14 but decreases to less than 3 percent by day 28 [5].

The technical steps include:

●Apply a noncrushing intestinal clamp (eg, Doyen) 5 cm proximal to the cut end on the colon side to control spillage. A distal clamp can also be applied. Lembert sutures are placed in the seromuscular tissue with 4-0 silk suture using a running or interrupted technique at the discretion of the surgeon.

If performing the anastomosis with an interrupted technique (figure 20):

•Place the first sutures at the mesenteric and antimesenteric corners.

•Place sutures 3 to 4 mm apart and 3 to 4 mm back from the edge to invert the bowel.

•Gently tie sutures to approximate tissue without tension.

•Additional sutures can be used to buttress any gaps.

If performing the anastomosis with a running technique (figure 21):

•Place one suture at the antimesenteric and another at the mesenteric border.

•Begin the anastomosis by starting at the antimesenteric border and progress to the mesenteric border, using the seromuscular technique.

•Turn the bowel over and use mesenteric border suture to complete running anastomosis.

•An interrupted suture can be used to buttress any gaps.

Stapled anastomosis — An alternative to the hand-sewn is the stapled anastomosis. While a stapled anastomosis is faster to perform, it requires specialized, costly equipment.

End-to-end — The most frequently used stapled approach for a colorectal anastomosis is the end-to-end anastomosis. The general principles for performing an end-to-end colorectal anastomosis include (figure 22):

●Place a pursestring suture at the proximal resection margin and insert the anvil of the circular stapler into the lumen. Secure the pursestring around the shaft.

●Staple the upper rectum transversely with a linear stapler.

●Insert the trocar of the circular stapler transanally into the rectal stump and advance to the staple line.

●Extrude the trocar just anterior to the staple line of the rectum under direct vision.

●Connect the anvil to the instrument, close and fire to create the anastomosis.

●Remove the stapler transanally and examine the circular margins (also called donuts). The margins must be intact and full thickness for the anastomosis to be constructed properly. The central section of the staple line on the rectum of the rectal stump is excised with the circular stapler. Leaving this staple line intact either anterior or posterior to the circular staple line will compromise the anastomosis.

Side-to-end — A stapled side-to-end anastomosis is performed when there is a notable size discrepancy between the ends of the bowel or based upon surgeon preference. In this situation, the side of the proximal colon is stapled to the end of the distal bowel (eg, upper rectum).

The general principles for performing a side-to-end colorectal anastomosis include:

●Make a colotomy in the proximal colon, approximately 3 to 4 cm from the end on the antimesenteric border.

●Insert the anvil into the lumen of the proximal colon, with the stem protruding through the colotomy, and secure with a pursestring suture.

●Staple the lumen of the proximal bowel with a linear stapler.

●The trocar is inserted transanally and the procedure completed as described in the preceding section.

Functional end-to-end — This anastomosis can be performed in the setting of a mobile distal colon and is not suitable for a colorectal anastomosis. The proximal and distal resection margins are divided with a linear stapling device in preparation for the anastomosis.

The general principles for performing a functional end-to-end colocolic anastomosis include (figure 23):

●Excise the antimesenteric corner of the staple line of the proximal and distal colon.

●Pass a limb of the linear stapler into each lumen along the antimesenteric border, close and fire to create the anastomosis.

●Close the remaining enterotomy with a linear stapler, a transverse stapler, or sutures.

Leak testing — Anastomoses should be tested for leaks. The colocolic anastomosis is submerged in saline to identify an air leak. The colorectal anastomosis is evaluated with rigid proctoscopy while submerging the anastomosis in saline. The staple line is inverted with nonabsorbable sutures if a leak is identified, and the assessment process is repeated until no leak is identified.

COMPLICATIONS — Complications of a colectomy include surgical site infection, splenic injury, ureteral injury, anastomotic leak, intra-abdominal abscess, enteric fistula, bleeding, and postoperative bowel obstruction. The frequency and management of intra-abdominal complications and anastomotic complications of colorectal surgery are reviewed separately. (See "Management of intra-abdominal, pelvic, and genitourinary complications of colorectal surgery" and "Management of anastomotic complications of colorectal surgery".)

Preventing complications

●Splenic injury – Injury to the spleen can occur during the dissection of the splenic flexure. Management of a splenic injury is discussed separately. (See 'Lateral-to-medial approach' above.)

●Ureteral injury – The key to prevention of an injury to the ureter is identification. Management of intraoperative ureteral injuries is discussed separately. (See 'Lateral-to-medial approach' above.)

●Anastomotic ischemia – The proximal and distal margins should be well vascularized to reduce the risk of an anastomotic dehiscence or leak. If the ends do not bleed or pulsatile vessels cannot be palpated near the lumens, further proximal and/or distal resection to viable bowel is performed. (See 'Arterial supply' above and 'Colocolonic anastomosis' above.)

POSTOPERATIVE CARE AND FOLLOW-UP — Postoperative management of colectomy patients has evolved, with contemporary emphasis on early postoperative feeding, early ambulation, reduction of perioperative fluid volume, pain management, and avoidance of intra-abdominal drains [6-13]. (See "Overview of colon resection", section on 'Postoperative care and follow-up'.)

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: Colorectal cancer" and "Society guideline links: Colorectal surgery for cancer".)

SUMMARY AND RECOMMENDATIONS

●Definition – A left hemicolectomy includes the resection of the transverse colon left of the middle colic vessels to the level of the upper rectum.

●Indications for left colectomy – The indications for a left colectomy include benign conditions (eg, segmental Crohn's colitis, trauma, ischemia, polyps unresectable through a colonoscope) and malignant diseases (eg, distal transverse colon cancer, mid-descending colon cancers). (See 'Indications' above.)

●Intraoperative challenges of left colectomy – Intraoperative challenges include splenic injury, ureteral injury, inadequate blood supply to resection margins, and synchronous unanticipated colon cancers. (See 'Complications' above and 'Preventing complications' above.)

●Colonic anastomosis – The continuity of bowel is restored with a colocolic or colorectal anastomosis, depending on the length of the distal bowel available for an anastomosis. At the surgeon's discretion, the anastomosis can be performed hand-sewn or stapled, using an end-to-end or end-to-side approach. A functional side-to-side anastomosis is an alternative approach for a colocolic anastomosis with mobile distal bowel. (See 'Colocolonic anastomosis' above.)