Initial evaluation and management of abdominal stab wounds in adults

INTRODUCTION — Until the 20^th century, nearly all penetrating injuries to the abdomen were managed nonoperatively. Beginning at World War I with the availability of general anesthesia, surgeons reported lower mortality among soldiers with penetrating abdominal wounds who were managed with laparotomy. Ultimately, laparotomy became the standard approach for treatment of such wounds. It gradually became clear that penetrating abdominal trauma sustained during warfare (mostly higher velocity gunshot wounds and incendiary devices) was different than penetrating abdominal trauma sustained by civilians (mostly stab wounds and lower velocity gunshot wounds) [1]. In 1960, Shaftan questioned the dogma of mandatory laparotomy for all penetrating abdominal injuries, and laparotomy rates for abdominal stab wounds have declined steadily over the ensuing decades [2].

This topic review will discuss the initial evaluation and management of abdominal stab wounds in adults. General trauma resuscitation in adults and children, blunt abdominal trauma, abdominal gunshot wounds, and other aspects of trauma care are reviewed separately. (See "Initial management of trauma in adults" and "Initial evaluation and management of blunt abdominal trauma in adults" and "Initial evaluation and management of abdominal gunshot wounds in adults" and "Trauma management: Approach to the unstable child" and "Approach to the initially stable child with blunt or penetrating injury".)

EPIDEMIOLOGY — Although there will be regional variability in the mechanism of injury producing abdominal trauma, most studies indicate that blunt abdominal trauma is more common than abdominal stab wounds, and that abdominal stab wounds are more common than abdominal gunshot wounds in the civilian population [3]. Abdominal gunshot wounds, due to their higher kinetic energy, are associated with mortality rates approximately eight times higher than abdominal stab wounds [4].

In children and adults alike, hollow viscus organs (intestines) are injured most often with abdominal stab wounds [3,5,6]. The next most common sites of injury are the great vessels, diaphragm, mesentery, spleen, liver, kidney, pancreas, gallbladder, and adrenal glands. The specific organs at greatest risk from a stab wound depend upon the location and mechanism of the injury.

MECHANISM OF INJURY — Any instrument that can impale may inflict a stab wound. Typically these are narrow, sharp, knife-like implements, but items that can inflict stab wounds range from scissors to coat hangers to animal horns. The given instrument can injure any tissue it traverses, including skin, fascia, solid organ, hollow viscus, blood vessel, nerve, muscle, and bone.

According to one series, the majority of abdominal stab wounds with evisceration occurred in the left upper quadrant of the abdomen, followed by the left lower, the right upper, and the right lower [6]. Posterior (ie, back) and flank stab wounds have a greater risk of injury to retroperitoneal structures, including the colon, kidneys, aorta, and inferior vena cava. Multiple stab wounds are present in 18 to 34 percent of patients, and as many as 30 percent of penetrating chest injuries traverse the diaphragm, potentially harming abdominal viscera [7]. Accordingly, anterior stab wounds that are inferior to the nipple line (fourth intercostal space) and posterior stab wounds that are inferior to the tip of the scapula (seventh intercostal space) should be considered to involve potential diaphragm and intra-abdominal injuries in addition to chest injuries. (See "Initial evaluation and management of penetrating thoracic trauma in adults" and "Recognition and management of diaphragmatic injury in adults".)

ANATOMIC ZONES — The abdominal cavity is divided into four anatomic zones (figure 1 and figure 2 and figure 3 and figure 4 and figure 5). The anterior abdomen is bound by the anterior axillary lines laterally, extending from the costal margins to the groin creases. Due to diaphragmatic excursion while breathing, the nipple line (fourth intercostal space) anteriorly and the tips of the scapulae (seventh intercostal space) posteriorly should be used to define the cephalad portion of the abdomen. Wounds in the upper abdominal region pose a significant threat of injury to the chest and abdomen depending upon the path of the weapon and the position of the diaphragm at the time of injury.

The flanks are separated on each side by the inferior costal margins and iliac crests, and the anterior and posterior axillary lines. The back is defined as the area between the posterior axillary lines, the inferior scapular tips (seventh intercostal space), and the iliac crest. Back and flank stab wounds have a greater risk of injury to retroperitoneal structures, including the colon, kidneys, duodenum, aorta, and inferior vena cava.

HISTORY — Answers to the following questions help to guide the clinician in assessing potential injuries from abdominal stab wounds:

●What instrument was used?

●How long and how wide was the instrument?

●How was the patient positioned during the stabbing?

●What path (or paths in the event of multiple wounds) did the instrument travel?

●Was there substantial blood loss at the scene?

METHODS OF EVALUATION

Initial assessment — General evaluation and the initial management of the trauma patient is reviewed separately. Issues specifically related to the initial evaluation of adult patients with stab wounds are discussed below (see "Initial management of trauma in adults"). An algorithm to help guide the management of patients with an anterior abdominal stab wounds is provided (algorithm 1).

It is important to completely undress the patient who sustains a stab wound. Stab wounds can often be obscured by body habitus, clothing, or bleeding, or be "hidden" in the scalp, axilla, perineum, or groin. Examine the patient carefully for evidence of more than one stab wound. Remember that the greatest danger may not be from the most obvious or immediately apparent injury. Clinicians should be wary of lacerations reported to be, or that appear to be, from blunt trauma; such wounds may represent penetrating trauma associated with significant internal injury.

The options for assessment and management of patients with abdominal stab wounds are determined by their clinical presentation. Patients presenting in extremis may require resuscitative thoracotomy (RT) or resuscitative endovascular balloon occlusion (REBOA) prior to emergency laparotomy to control hemorrhage or manage other injuries. Emergency thoracotomy and REBOA are discussed in detail separately. (See "Resuscitative thoracotomy: Technique" and "Initial evaluation and management of penetrating thoracic trauma in adults", section on 'Role of emergency department thoracotomy' and "Endovascular methods for aortic control in trauma".)

Patients with any of the following typically go immediately to the operating theater for laparotomy:

●Hemodynamic instability

●Peritonitis

●Impalement

●Evisceration

●Blood from a nasogastric tube or on rectal examination

In patients without indications for immediate laparotomy, physical examination is both sensitive and specific for detecting significant intra-abdominal injury. In a prospective observational study of 359 patients with anterior abdominal stab wounds, physical examination including local wound exploration was found to be an effective tool for distinguishing between patients warranting laparotomy and those suitable for close clinical observation [8]. No apparent difference in morbidity was noted between these patient groups. A subsequent observational study involving 249 consecutive abdominal stab wound patients treated at a major trauma center found physical examination to be 100 percent sensitive and 98.7 percent specific for detecting intra-abdominal injury necessitating laparotomy [9]. The authors concluded that a physical examination based diagnostic algorithm was more effective than CT and decreased radiation exposure.

Patients without apparent indications for laparotomy may be evaluated by one or more of the following techniques:

●Local wound exploration (LWE)

●Plain radiograph

●Computed tomography (CT)

●Serial physical examinations (SPE)

●Diagnostic peritoneal lavage (DPL)

●Ultrasonography

●Laparoscopy

Local wound exploration — Since the entire abdominal wall is encased in a layer of fascia, the first question in asymptomatic patients is to determine whether the stab wound violated the peritoneum. Stab wounds are amenable to local wound exploration (LWE) to evaluate their depth and tract [10]. LWE is safely performed at the bedside in patients with stab wounds to the anterior abdomen, but requires appropriate patient sedation and local anesthesia. The procedure, best undertaken by two individuals, should be done with sterile technique, good lighting and both sharp and blunt dissection until the bottom of the wound is clearly visualized. Blunt probing with fingers or cotton swabs is unreliable and not recommended. Adequate analgesia and appropriate sedation must be provided when performing LWE. In some cases, local infiltration of tissues with anesthetic is sufficient, but standard procedural sedation and analgesia (PSA) may be required. The performance of PSA is discussed separately. (See "Procedural sedation in adults in the emergency department: General considerations, preparation, monitoring, and mitigating complications".)

For anterior stab wounds, if the exploration to the deepest extent of the wound demonstrates that anterior rectus fascia is not violated, then patients may be discharged after appropriate wound care, assuming no additional or extra-abdominal injuries are present [10,11]. In a prospective trial of 252 patients with anterior stab wounds, the reported sensitivity and specificity of LWE (performed by general surgeon in the emergency department) for peritoneal violation were both 100 percent [12]. Excessive fat tissue, dense muscle, or the presence of multiple wounds or other injuries can compromise LWE [13,14]. If the anterior fascia is not clearly and completely seen, peritoneal injury cannot be ruled out and further evaluation is required. For clinicians with limited experience performing LWE, or those who have not performed one in some time, the safest policy is to presume peritoneal violation unless all edges of the wound are visualized clearly.

Plain radiographs — Plain radiographs typically add little to the management of abdominal stab wounds. If free intraperitoneal air is seen on an upright chest or lateral decubitus radiograph, then the peritoneal cavity has been violated, but this does not confirm hollow viscus injury. Thus, plain radiographs lack sensitivity and specificity for significant injuries and are rarely employed in this setting.

An exception is the use of plain radiographs to look for foreign bodies. These include cases of impalement where the foreign object remains in the patient and cases where there is concern for a retained foreign body not visible in the wound, such as a broken knife blade.

Serial physical examination and observation — It is well accepted that serial physical examination (SPE) is a safe and reliable means to detect significant intra-abdominal injuries after stab wounds to the abdomen, if performed by experienced clinicians on appropriate patients. Ideally, the same clinician should perform each examination.

Patients not appropriate for SPE include those with an unreliable examination due to head injury, spinal cord injury, altered mental status (eg, from intoxication), or the need for general anesthesia. In addition to careful reassessment of the abdomen, the physical examination should include assessment of the neurologic and vascular status of the lower extremities as stab wounds may damage nerves and vessels in the abdomen and pelvis. Ideally, serial examinations are performed at least every six hours.

The requisite duration of observation after a stab wound to the abdomen that penetrates the anterior rectus fascia is at least 12 hours [15]. Patients in the following categories should be observed for at least 24 hours:

●Older than 65 years

●Taking anticoagulants or antiplatelet medications at the time of injury or have advanced liver disease with coagulopathy

●Have significant medical comorbidities that may affect detection of internal injury (eg, diabetes, advanced liver disease)

●Have other significant injuries warranting observation

Mildly intoxicated patients should be observed until the effects of the intoxicating substance have resolved. Assuming no signs of significant injury are detected, such patients may be discharged following a final reassessment and reexamination.

Some basic criteria that the patient with an abdominal stab wound should meet to be considered appropriate for discharge after brief observation (12 hours) include the following:

●Mentally capable of making appropriate, informed decisions about medical care

●Physical examination – including careful abdominal examination – is unremarkable, with the lone exception of some reasonable discomfort at the stab wound site only

●Vital signs are stable and without concerning trends: Heart rate less than 90 beats per minute; respiratory rate less than 14 breathes per minute; temperature less than 38°C (100.4°F)

●Spontaneous urination

●Tolerating oral fluids

●Able to ambulate safely

●Not taking anticoagulants or antiplatelet therapy

●Safe discharge environment

Ultrasound — Bedside extended Focused Abdominal Sonography for Trauma (eFAST) examination is frequently used to determine the presence of hemopericardium, hemoperitoneum, pneumo- or hemothorax, or some combination thereof. Overall, the specificity of the FAST examination for identifying signs of internal injury from a stab wound appears to be high, but sensitivity is limited. The use of ultrasound (US) in evaluating patients with abdominal trauma is described in detail separately. (See "Emergency ultrasound in adults with abdominal and thoracic trauma".)

The eFAST examination is particularly valuable in the initial assessment of a patient with a low chest or upper abdominal stab wound who is hemodynamically unstable, as rapid identification of hemopericardium or hemoperitoneum can help to determine the priorities of management. Hemopericardium causing hemodynamic compromise (ie, pericardial tamponade) must be drained immediately. Unstable patients with hemoperitoneum and no sign of hemopericardium or another immediately treatable cause of hypotension (eg, pneumothorax) should proceed to immediate laparotomy. (See "Emergency pericardiocentesis" and 'General approach and indications for laparotomy' below and "Initial evaluation and management of penetrating thoracic trauma in adults", section on 'Cardiac injury'.)

In hemodynamically stable patients with a positive eFAST, other diagnostic modalities, such as computed tomography (CT) or diagnostic laparoscopy, can identify specific injuries and guide management. In those with a negative eFAST, injury cannot be excluded and other diagnostic modalities must be employed.

Other applications of US in penetrating abdominal trauma continue to evolve. While it is not routinely used to diagnose peritoneal penetration, a small study using the US transducer to assess fascial violation deep to the stab wound demonstrated excellent specificity but suboptimal sensitivity [16].

Diagnostic peritoneal tap and diagnostic peritoneal lavage — Diagnostic peritoneal tap and lavage is a rapid and easily performed invasive bedside procedure that offers information about peritoneal penetration and injury to solid organs, bowel, and the diaphragm. Diagnostic peritoneal lavage (DPL) does not assess the retroperitoneum. The procedure entails inserting a catheter into the peritoneal cavity, initially to aspirate blood or fluid, and subsequently to infuse fluid and lavage the cavity, if necessary. The initial portion of the procedure is often referred to as a diagnostic peritoneal tap or aspirate; the latter portion is a DPL. DPL is discussed in detail separately; aspects of the procedure that are of particular importance to assessment of abdominal stab wounds are mentioned below. (See "Diagnostic peritoneal lavage (DPL) or aspiration (DPA)".)

In the setting of abdominal stab wounds, diagnostic peritoneal tap and lavage is generally used for one of the following indications:

●Need to rapidly determine the presence of hemoperitoneum in unstable patients when ultrasound is not diagnostic

●Need to diagnose diaphragm injury (eg, unclear if a stab wound to the left lower chest has penetrated the peritoneum)

In the hemodynamically unstable patient, DPL has been used to identify hemoperitoneum when the physical examination is equivocal or ultrasound is technically inadequate. DPL may be particularly important for guiding management in the patient with multiple stab wounds and other potential causes for hypotension, such as hemothorax, pericardial tamponade, spinal cord injury, and retroperitoneal hemorrhage.

In patients with stab wounds of the anterior abdomen who are hemodynamically stable and without indications for immediate laparotomy, the clinician should determine whether peritoneal violation has occurred. If the peritoneum has been violated or the clinician is uncertain whether it has, serial physical examination is the most cost effective means of assessing for significant intraperitoneal injury [17]. DPL may be a useful procedure when intraperitoneal injury must be assessed in patients who will become difficult to reevaluate, such as those who will undergo general anesthesia for a procedure other than laparotomy. However, in most circumstances ultrasound or CT scan is used to evaluate stable patients rather than DPL.

Relative contraindications to DPL include previous abdominal surgery, preexisting coagulopathy, advanced cirrhosis, excessive abdominal fat, and pregnancy beyond the first trimester. The supraumbilical approach to the DPL is advised in patients with a pelvic fracture or females beyond the first trimester of pregnancy.

Most experts agree that the aspiration of 10 mL of gross blood in a patient with penetrating abdominal wounds indicates visceral injury [18,19]. However, debate continues over the appropriate red blood cell count threshold for determining visceral injury if the initial aspirate is negative or inconclusive and lavage is performed. A commonly used threshold is the presence of greater than 10,000 red blood cells per high-powered field (RBCs/HPF). A range of 5000 to 10,000 RBCs/HPF is often used to determine the presence of injury in thoracoabdominal (low chest) wounds, as this lowered threshold allows greater sensitivity for detecting isolated diaphragmatic or small bowel injury [18,20]. This degree of RBC concentration in the DPL effluent should not be attributed to the procedure itself. The interpretation DPL aspirates is discussed in greater detail separately. (See "Diagnostic peritoneal lavage (DPL) or aspiration (DPA)", section on 'Fluid interpretation'.)

Computed tomography and magnetic resonance imaging — Multidetector CT (MDCT) is a noninvasive and rapidly performed imaging study that enables clinicians to delineate visceral and vascular injury [7,21,22]. A systematic review and observational studies cite a sensitivity of up to 97 percent coupled with a specificity of up to 98 percent for identification of peritoneal violation [7], and a sensitivity of 94 percent and specificity of 95 percent for detecting significant intra-abdominal injuries possibly requiring operative management [23]. Another advantage of CT is that it enables the identification of intraperitoneal injuries, such as hepatic lacerations, that may be amenable to nonoperative management [7]. A systematic review and meta-analysis of one randomized trial and three observational studies (319 total patients) comparing SPE with CT in the assessment of anterior abdominal stab wounds found no additional benefit from imaging [24].

Although previous studies of CT involved triple contrast (intravenous, oral, and rectal), the advent of high-resolution, multidetector scanners makes this approach unnecessary in most cases of isolated anterior abdominal stab wounds [22]. The preferred approach to imaging is best determined in consultation with the trauma surgeon and radiologist, but in most cases rectal contrast is no longer needed.

Even with a negative initial CT scan, patients at risk for diaphragmatic or bowel injury should have further testing, or observation and serial examinations, as these injuries are the ones most frequently missed [25]. A 2018 systematic review of studies of patients with anterior abdominal stab wounds concluded that a negative CT of the abdomen and pelvis was inadequate to exclude surgically significant injury and safely discharge patients without a period of observation with serial physical examinations [26]. Although, the accuracy of MDCT scans for detecting these conditions is improving [27], magnetic resonance imaging (MRI) has greater sensitivity for some injuries and may play a useful role in evaluating the stable pregnant patient in need of intra-abdominal or thoracoabdominal imaging following penetrating injury [27,28]. (See "Recognition and management of diaphragmatic injury in adults" and "Management of duodenal trauma in adults", section on 'Diagnosis' and "Traumatic gastrointestinal injury in the adult patient" and "Management of pancreatic trauma in adults", section on 'Diagnosis'.)

Diagnostic laparoscopy — Diagnostic laparoscopy (DL) is most useful for inspecting the diaphragm in thoracoabdominal wounds and determining the feasibility of nonoperative management of isolated liver injuries [29-31]. DL is used more commonly in Europe and South America where there is greater enthusiasm for laparoscopic repair of hollow viscous injuries. The accuracy of DL in identifying injuries varies according to the location and type of injury [30]. In general, laparoscopy or thoracoscopy is useful for identifying diaphragmatic wounds and facilitates minimally invasive repair [32]. However, complete assessment of all hollow organs can be challenging and the retroperitoneum cannot be evaluated easily.

INITIAL MANAGEMENT

General approach and indications for laparotomy — The initial evaluation and resuscitation of the patient with an abdominal stab wound are identical to that for any acutely injured patient and are discussed in detail separately (see "Initial management of trauma in adults"). An algorithm to help guide the management of patients with an anterior abdominal stab wounds is provided (algorithm 1).

After necessary resuscitation, patients with any of the following typically go immediately to the operating theater for laparotomy [33]:

●Hemodynamic instability

●Peritonitis

●Impalement

●Evisceration

●Gross blood from a nasogastric tube or on rectal examination

In the remaining patients, the first management decision is whether there is violation of the peritoneum or retroperitoneum. For anterior abdominal stab wounds, peritoneal penetration is the key decision point. This can often be determined by local wound exploration (LWE), but advanced imaging studies are sensitive and specific when LWE is difficult.

Evisceration of omentum or abdominal viscera represents peritoneal violation and most believe this warrants laparotomy because of the high risk of gastrointestinal perforation [33,34]. The rate of intra-abdominal injury in patients with evisceration is higher than those without [35]. However, nonoperative approaches may be reasonable in some patients. In a study of 405 consecutive cases of omental evisceration from stab wounds, 181 patients were observed initially, and of these, 20 ultimately required laparotomy [36]. There were no differences in morbidity or mortality between patients treated with immediate laparotomy and those managed initially with close clinical assessment. Despite the increased role for nonoperative management, evisceration continues to be an indication for laparotomy in most centers, although laparoscopy is a reasonable alternative.

For flank and back wounds, there is a risk of retroperitoneal as well as peritoneal penetration (figure 2). In addition, there is concern for peritoneal violation with anterior lower thoracic stab wounds, and retroperitoneum injury with lower posterior chest wounds. Hemodynamically stable patients with these potentially more complex wounds (flank, back, thoracoabdominal) warrant careful evaluation, which may include CT imaging and a period of observation. (See 'Flank and back stab wounds' below and 'Thoracoabdominal stab wounds' below and 'Right upper quadrant stab wound' below.)

Signs of gastrointestinal hemorrhage (eg, hematemesis, hematochezia) suggest gastroduodenal or colorectal injury and generally warrant laparotomy without further investigation by imaging study. An implement in situ (ie, a weapon protruding from the patient's body) ordinarily prompts laparotomy, even in stable patients, in case the implement rests inside an intraperitoneal vessel, such that removal would lead to hemorrhage. High risk surgical candidates and pregnant patients, for whom laparotomy puts the fetus at risk, may undergo removal of the implement without general anesthesia but in the operating suite whenever feasible in case they deteriorate.

Peritoneal violation — Peritoneal violation occurs in 50 to 70 percent of patients with abdominal stab wounds, but only half of those with peritoneal violation sustain an intra-abdominal injury requiring operative intervention [34]. Thus, only 25 to 33 percent of patients with abdominal stab wounds require laparotomy. In most major trauma centers, local wound exploration (LWE) is performed to determine peritoneal penetration for anterior abdominal stab wounds. If no violation of the anterior rectus fascia has occurred, the patient may be discharged safely after local wound care, assuming there are no other injuries of concern. (See 'Local wound exploration' above.)

In centers without extensive experience with abdominal stab wounds, the alternative tests to evaluate for peritoneal penetration are DPL or CT scanning. Patients with a negative DPL or CT scan require at least another 12 hours of observation because of the risk of missing a gastrointestinal perforation. (See 'Diagnostic peritoneal tap and diagnostic peritoneal lavage' above and 'Computed tomography and magnetic resonance imaging' above.)

Selective nonoperative management — With increased use of sophisticated diagnostic modalities, more trauma centers are managing nonoperatively those patients without indications for immediate laparotomy. Nontherapeutic and negative laparotomy rates, as well as overall lengths of hospital stay and cost, are reduced using this approach [11,17,37-39].

In a prospective study of 256 consecutive patients with an abdominal stab wound, 46 (18 percent) required immediate laparotomy and 210 (82 percent) were evaluated by CT, of whom 174 patients (68 percent) met appropriate criteria for nonoperative management [40]. Of the patients managed nonoperatively, three (2 percent) developed signs necessitating laparotomy, and all did so within 24 hours; there were no other clinically significant complications among patients managed nonoperatively. A systematic review of two studies including 114 patients with penetrating abdominal injury concluded that there is no evidence to support the use of surgery over an observation protocol for patients with penetrating abdominal trauma who are stable with no signs of peritonitis [41]. The approach to selective nonoperative management varies by injury and is discussed in greater detail separately. (See "Traumatic gastrointestinal injury in the adult patient", section on 'Approach to management' and "Overview of the diagnosis and initial management of traumatic retroperitoneal injury", section on 'Nonoperative management'.)

Prophylactic antibiotics — Broad spectrum antibiotics are given to patients with penetrating abdominal injury requiring surgical management; however, antibiotic administration is not warranted in injured patients who are managed nonoperatively. The use of prophylactic antibiotics in the setting of trauma is discussed separately. Tetanus prophylaxis should be given as indicated. (See "Overview of inpatient management of the adult trauma patient", section on 'Antibiotics' and "Infectious complications of puncture wounds", section on 'Tetanus immunization'.)

Coagulation testing — Coagulation studies should be obtained for patients on anticoagulants or dual antiplatelet therapy, or with possible cirrhosis. Ideally, a viscoelastic assay (eg, thromboelastography or rotational thromboelastometry) should be part of this assessment. (See "Etiology and diagnosis of coagulopathy in trauma patients", section on 'Viscoelastic hemostatic assays' and "Platelet function testing", section on 'Viscoelastic testing (TEG and ROTEM)'.)

Observation in resource-limited settings — Clinicians in rural emergency departments or other resource-limited settings must decide whether to observe patients with an abdominal stab wound who are hemodynamically stable and without obvious signs of intra-abdominal injury (including normal abdominal examination) at their institution or to transfer them to a hospital with the resources necessary to provide definitive care should the patient’s condition deteriorate. There is no single best answer to this question and the decision will vary depending upon such factors as patient characteristics (eg, major comorbidities, advanced age) and distance from the closest hospital capable of providing definitive care.

In general, we believe it is reasonable in most cases to keep such patients at a resource-limited facility for observation, even if LWE cannot be performed or is equivocal and CT cannot be obtained or is negative initially. Should the patient begin to manifest signs of intra-abdominal injury (eg, worsening abdominal pain) or vital signs show a concerning trend (eg, increase in heart rate or respiratory rate, decline in blood pressure), the patient should be transferred immediately. One exception to this general approach would be if the time needed to reach definitive care is prolonged (longer than approximately six hours) due to distance or weather. In such cases, it makes sense to transfer the patient early when possible.

SPECIAL CONSIDERATIONS

Flank and back stab wounds — Identifying structures injured from penetrating wounds to the flank and back can be difficult. Stab wounds to these regions can injure both retroperitoneal and intraperitoneal structures. Several reports indicate that up to 40 percent of penetrating flank wounds result in significant internal injury [8,42]. In the past, triple-contrast computed tomography (CT) was the study of choice for stable patients with such wounds, but with advanced, high-resolution, multidetector CT (MDCT) scanners, IV contrast is likely all that is needed to assess possible retroperitoneal injury from back or flank wounds [8,42,43]. Such advanced imaging often allows for safe nonoperative management. Ultrasound (US) and diagnostic peritoneal lavage (DPL) do not adequately assess retroperitoneal structures.

Thoracoabdominal stab wounds — Thoracoabdominal wounds present a diagnostic challenge as movement of the diaphragm makes prediction of the stab wound tract difficult [44]. If the wound is close to the lower chest, intrathoracic and diaphragmatic injuries must be considered and evaluated in addition to intra-abdominal injury. Pericardial tamponade is particularly important to consider in stab wounds near the xyphoid process.

The risk of complications from a missed left-sided diaphragmatic injury is high (the liver generally prevents small bowel herniation on the right side). However, controversy continues about how best to evaluate possible diaphragm injuries. If diaphragmatic injury is a concern, diagnostic laparoscopy (DL) or thoracoscopy are the preferred tests because CT is relatively insensitive [45,46]. Some experts use diagnostic peritoneal lavage with the lower threshold of 5000 red blood cells per high powered field (RBCs/HPF) as the criterion for exploratory laparotomy. Diaphragmatic injury is discussed in detail separately. (See "Recognition and management of diaphragmatic injury in adults" and 'Diagnostic laparoscopy' above and 'Computed tomography and magnetic resonance imaging' above and 'Diagnostic peritoneal tap and diagnostic peritoneal lavage' above.)

Right upper quadrant stab wound — Patients with a right upper quadrant stab wound who remain hemodynamically stable and free of abdominal tenderness, and who are reliable (eg, not intoxicated and remain alert) may be managed without laparotomy [25]. Most patients with injuries of this nature have sustained grade I or grade II hepatic injuries that do not require operative intervention. However, these patients should be admitted for a period of observation of at least 48 hours. Many centers perform CT scanning to confirm and determine the extent of any hepatic wounds and to assess for potential colonic injury. If the severity of liver injury cannot be determined with certainty by CT scan, most trauma surgeons perform diagnostic laparoscopy. The physical examination cannot be considered reliable in patients with a brain injury, spinal cord injury, or intoxication, or who require sedation or general anesthesia, and serial physical examination is not an appropriate means of evaluation in these circumstances.

Stab wounds in pregnancy — Abdominal stab wounds sustained during pregnancy are uncommon. The management of the pregnant trauma patient is reviewed separately. (See "Initial evaluation and management of major trauma in pregnancy".)

Patients on anticoagulants or antiplatelet therapy — Patients taking warfarin, heparin, or other anticoagulants are at higher risk of hemorrhage following an abdominal stab wound and reversal of anticoagulation may be needed if bleeding becomes severe. Similarly, dual antiplatelet therapy increases the risk of bleeding. This is discussed separately. (See "Management of warfarin-associated bleeding or supratherapeutic INR", section on 'Treatment of bleeding' and "Heparin and LMW heparin: Dosing and adverse effects", section on 'Bleeding' and "Management of bleeding in patients receiving direct oral anticoagulants", section on 'Major bleeding'.)

Law enforcement and social service issues — Many jurisdictions require emergency departments to notify local law enforcement of all intentional stab wounds. Law enforcement investigation may be necessary to ensure that no other stab victims are in need of assistance. Necessary steps should be taken to ensure that the emergency department and hospital are safe and secure, which may include communicating with hospital security or police personnel. Clothing removed from the patient should be placed in brown paper bags or other containers suitable for evidence collection, and care should be taken to avoid cutting through rips or knife cuts in garments whenever possible. All wounds should be carefully documented in the medical record.

Victims of assault may suffer emotionally as well as physically. Social services or mental health professionals should be consulted as appropriate during the hospital evaluation and as part of post-discharge follow-up. (See "Acute stress disorder in adults: Epidemiology, clinical features, assessment, and diagnosis".)

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: General issues of trauma management in adults" and "Society guideline links: Traumatic abdominal and non-genitourinary retroperitoneal injury" and "Society guideline links: Thoracic and lumbar spine injury in adults".)

SUMMARY AND RECOMMENDATIONS

●History – Whenever possible, obtain a history of the abdominal stab wound from the patient and emergency medical services personnel, law enforcement, or other witnesses. (See 'History' above and 'Initial assessment' above.)

Important questions include:

•What instrument was used? how long and how wide was it?

•How was the patient positioned during the stabbing?

•What path did the implement travel (eg, upward, downward)?

•Was there substantial blood loss at the scene?

•When did the stabbing occur?

●Indications for laparotomy and management algorithm – Indications for emergency laparotomy include:

•Hemodynamic instability

•Peritoneal signs on physical examination

•Signs of gastrointestinal hemorrhage

•Implement in situ.

Evisceration of intra-abdominal viscera or omentum is an indication for immediate laparotomy at most trauma centers but may be managed with diagnostic laparoscopy. Broad spectrum antibiotics are given to patients with penetrating abdominal injury requiring surgical management, but otherwise are not administered empirically. An algorithm to help guide the management of patients with an anterior abdominal stab wounds is provided (algorithm 1). (See 'General approach and indications for laparotomy' above.)

●Physical examination – Undress completely any patient who sustains a stab wound. Stab wounds can often be obscured by body habitus, clothing, or bleeding, or be "hidden" in the axilla, scalp, or groin. The most obvious wound may not be the most concerning wound.

Stab wounds to the abdomen, flank, or back are often amenable to local wound exploration (LWE) to evaluate their depth and tract. If a properly performed exploration to the deepest extent of the wound demonstrates that anterior rectus fascia is not violated, the patient may be discharged after appropriate wound care, assuming no additional or extra-abdominal injuries are present. If body habitus, multiple wounds, other injuries, or difficulty in performing LWE impedes visualization of the complete depth of the wound and all its margins, then peritoneal injury cannot be ruled out and further testing or observation must ensue. (See 'Local wound exploration' above.)

●Diagnostic imaging

Plain radiographs – Plain radiographs are seldom useful for evaluating abdominal stab wounds, with the exception of assessing retained foreign bodies such as impaled objects. (See 'Plain radiographs' above.)

Ultrasound – Bedside extended Focused Abdominal Sonography for Trauma (eFAST) examination is frequently used to determine the presence of hemopericardium, hemoperitoneum, pneumothorax, hemothorax, or some combination thereof. Overall, the specificity of the FAST examination for identifying signs of internal injury from a stab wound appears to be high, but sensitivity is limited. The use of ultrasound in evaluating patients with abdominal trauma is discussed in detail separately. (See "Emergency ultrasound in adults with abdominal and thoracic trauma".)

Computed tomography (CT) – Multidetector computed tomography (MDCT) is a noninvasive and fast imaging technique that enables accurate identification of peritoneal penetration and delineation of solid visceral and vascular injury. Patients with a high likelihood for diaphragmatic, bowel, or pancreatic injury should have further testing, or observation and serial examinations, even with a negative initial CT scan, as these injuries are missed most frequently. (See 'Computed tomography and magnetic resonance imaging' above.)

●Observation with serial examination – Observation with serial physical examination is a reliable approach for detecting significant injuries after stab wounds to the abdomen, assuming normal mental status and neurologic function, and the absence of distracting injury or sedation. Ideally, serial examinations should be performed by the same clinician. The optimal time period for observation of uncomplicated stab wound patients in a nonoperative management plan is at least 12 hours. Patients with complicating factors (eg, older age, comorbidities, taking anticoagulants or antiplatelet therapy, concerning trends with vital signs or the examination) warrant a longer period of observation. (See 'Serial physical examination and observation' above.)

●Multi-region stab wounds – Flank, back, and thoracoabdominal injuries may involve more than one anatomic space and can be difficult to evaluate. Stable patients with stab wounds to the flank or back are generally evaluated using MDCT. The morbidity and mortality associated with missed diaphragmatic injury on the left side is high. Patients with thoracoabdominal injury require thorough investigation, possibly with diagnostic laparoscopy or thoracoscopy. Patients with an isolated stab wound to the right upper quadrant may be managed without laparotomy if vital signs remain stable and the abdominal examination is reliable (eg, no alteration of mental status), and there is minimal to no abdominal tenderness. (See 'Special considerations' above.)

●Legal and other considerations – Clinicians should be aware of local legal requirements for reporting stab wounds and whenever possible take the necessary steps for proper evidence collection. Consultation with social service or mental health service personnel may be beneficial and appropriate outpatient referral to such services may be warranted.