Local Wound Exploration (LWE)

In the 19th century, penetrating abdominal wounds were managed nonoperatively. The associated morbidity and mortality rates were greater than 70%.[1 ]Experience gained during World War I, World War II, and the Korean Conflict led to an aggressive approach of operative management for all penetrating abdominal wounds.[2 ]This approach resulted in an unacceptably high frequency of laparotomy with findings negative for trauma. In 1960, Shaftan developed an approach of selective conservatism for penetrating abdominal injury and revolutionized abdominal stab wound management.[3 ]

The optimal method to determine the need for laparotomy has yet to be definitively established. Abdominal stab wound exploration forms part of a strategy developed by surgeons to allow a more selective approach. In asymptomatic patients with stab wounds to the anterior abdomen, 2 methods are widely used to help determine the need for laparotomy:

• Abdominal stab wound exploration (Subsequent diagnostic peritoneal lavage [DPL], serial clinical evaluation, or both are used to further assess patients in whom an exploration cannot definitively exclude peritoneal penetration.)
• Serial clinical evaluation

The objective is to reduce the number of patients with trivial or no intraperitoneal injury who are subjected to laparotomy. However, a high degree of diagnostic accuracy must be maintained to limit the frequency of missed injury. A reduction in unnecessary hospitalization is also targeted.

Investigators in this field are continuing to study other protocols and investigative tools. No protocol is currently universally accepted. Other modalities that have been studied include DPL alone, laparoscopy, CT, and ultrasonography. These strategies of selection for laparotomy are explored in greater detail below.

More than 25% of anterior abdominal stab wounds do not penetrate the peritoneal cavity.[5,6 ]Local wound exploration allows the safe discharge of these patients from the emergency department. Only half of the wounds that penetrate the peritoneum cause damage that requires surgical intervention.[1,7 ]The organs most commonly injured with anterior abdominal stab wounds are the small bowel, the liver, and the colon. Missed hollow viscus injuries are associated with significant morbidity and mortality.

The authors advocate abdominal stab wound exploration in asymptomatic patients who present with an anterior abdominal stab wound. An exploration with negative findings is reliable and highly sensitive. Abdominal stab wound exploration combined with further investigation, such as DPL or serial evaluation, achieves acceptable specificity rates. Minimizing the time taken to control ongoing intraperitoneal contamination is critical in penetrating stab wounds, and local exploration is a valuable first step in speeding up the decision-making process. When combined with DPL, abdominal stab wound exploration allows significant injuries that are not immediately apparent to be identified early.

Wound exploration can be performed successfully by surgeons or ED personnel who are trained in the procedure. This strategy aids with patient flow through a busy emergency department.

Flow chart illustrating the management options in patients with a stab wound to the anterior abdomen. Red arrows highlight an approach that favors abdominal stab wound exploration.

Anatomy

An appreciation of the anatomy of the anterior abdominal wall at different levels is essential to understanding the procedure. The differences are highlighted in red on the diagrams below.

Transverse section of the anterior abdominal wall above the arcuate line.

Transverse section of the anterior abdominal wall below the arcuate line.

Boundaries of the anterior abdomen:

• Costal margins (superior)
• Inguinal ligaments (inferior)
• Anterior axillary lines (lateral)

Boundaries of the anterior abdominal wall.

Indications

Abdominal stab wound exploration is indicated in a patient who presents with a stab wound to the anterior abdomen, normal vital signs, no signs of peritonitis, and no evidence of evisceration.

Stab wound to the anterior abdomen.

Some authors advocate local exploration of wounds only anterior to the midaxillary line. If the wound tracks anteriorly and the end point of the tract is not accurately determined, the patient undergoes diagnostic peritoneal lavage (DPL). If the wound tracks posteriorly and is not obviously superficial, the patient is investigated as for a penetrating flank wound. This often involves a triple-contrast CT scan.[8 ]

Special circumstances involve patients with additional injuries that require operative intervention and cases in which the offending weapon or object is retained.

• If the patient has additional injuries that require operative intervention, a wound exploration may be performed in the operating room before the other procedure is commenced.
• If the object has been retained and the surgeon strongly suspects that the peritoneum has not been breached, the object may be removed in the operating room and the wound locally explored. In such cases, the surgeon should be prepared to immediately convert to laparotomy, if necessary.

Contraindications

Abdominal stab wound exploration is contraindicated if immediate laparotomy is indicated. The situations in which immediate laparotomy is indicated include the following:

• Unstable patient
• Peritonitis
• Evisceration (This remains controversial; see paragraph 3 in Selecting Candidates for Laparotomy section.)
• Blood on rectal examination or blood in nasogastric tube aspirate suggests intra-abdominal injury (A low threshold for operative intervention is suggested.)

Other contraindications to abdominal stab wound exploration include the following:

• Lower chest wounds: Exploration of these wounds carries a high risk of iatrogenic pneumothorax.
• Flank and back wounds: Some authors advocate exploration of these wounds if they are suspected to be superficial. However, this expectation may be unreliable, and the strong musculature makes the tract difficult to predict or to follow. Local wound exploration may result in further injury or a restart of hemorrhage that had stopped.
• Patient refusal or uncooperative patient.

Relative contraindications include the following:

• Obesity
• Multiple abdominal stab wounds

Anesthesia

• Local anesthesia is used.
• Use liberally, as patient comfort is essential. The procedure requires patient compliance and adequate anesthesia. Hemostasis is also important.
• The authors’ suggested preparation is 1% lidocaine hydrochloride (10 mg/mL) with epinephrine 1:200,000 (5 mcg/mL). Other preparations can be used.
• The maximum dose of lidocaine combined with epinephrine is 7 mg/kg, up to 500 mg.
• Local exploration in uncooperative patients is best performed in the operating room under general anesthesia.

For more information, see Local Anesthetic Agents, Infiltrative Administration.

Equipment

• Adequate light source or operating lamp
• Sterile gloves
• Surgical masks
• Surgical caps
• Protective eyewear
• Sterile gowns
• Sterile drapes
• Cleaning solution (10% povidone iodine [Betadine] or other suitable solution)
• Lidocaine hydrochloride (1%) with epinephrine
• Gauze swabs
• Suture material (See Technique for suggestion of suture material.)
• Wound dressing
• Washout irrigant (1 L of 0.9% NaCl)
• Scalpel
• Blades, 2
• Retractors, 2
• Dissecting forceps (toothed and untoothed)
• Needle holder
• Scissors (curved dissecting and stitch scissors)
• Hemostats, 5
• Diathermy may be used, if available. Diathermy assists with achieving hemostasis.

Equipment required for an abdominal stab wound exploration.

Positioning

• The patient is positioned supine.
• Adequate exposure of the abdomen is essential.
• Abdominal stab wound exploration can be effectively performed in the emergency department

Technique

The critical concept is to determine the end point of the tract under direct vision.

• Ensure good lighting.
• Ensure hemostasis and adequate anesthesia.
• Extend the wound to allow good visualization.
• Use retractors and a trained assistant.
• Use a hemostat or other instrument as a guard to cut onto when exploring the depths of the wound. This assists with accuracy of dissection and prevents extending the wound at a deeper level than anticipated.
• The exploration usually takes 10-15 minutes. Meticulous dissection ultimately saves time.
• The exploration of an abdominal wound in patients who are markedly obese can be particularly challenging. In these patients, consider performing the procedure in the operating room with the patient under general anesthesia.
• Do not probe the wound with a finger or blunt object, as this can cause further hemorrhage, give a false impression of the tract, distort the anatomy of the wound, and introduce infection into the depths of the wound.
• Diathermy simplifies the exploration because it helps maintain hemostasis.
• When doubt exists, prudence involves further investigation, observation, or consideration for exploratory laparotomy.

Complications

Complications of abdominal stab wound exploration are rare (rate is approximately 1%). Complications include local wound infection and bleeding.

Published papers report no false-negative exploration findings.[5,9 ]

Selecting Candidates for Laparotomy

No debate exists about the management of patients who are hemodynamically compromised or who exhibit peritonitis upon abdominal examination. These patients are immediately transferred to the operating room and undergo laparotomy.

The optimal management for an asymptomatic patient with an anterior abdominal stab wound remains controversial. Routine laparotomy was once advocated but is no longer accepted practice. The universally accepted practice is now selective management of asymptomatic patients with stab wounds. However, the methods used to select those who will benefit from laparotomy are controversial.

No consensus has been reached regarding the treatment of patients with evisceration of omentum or an abdominal organ. Many still opt for operative intervention in this group and cite a high incidence of organ injury as the reason for their standpoint.[10,11 ]Demetriades and others have shown that these patients can also be successfully managed nonoperatively, provided that they are stable and that the findings of their abdominal examination remain benign.[12,13 ]

Methods that aid practitioners in the selection of patients whose injuries are likely to warrant laparotomy are an area of ongoing study. Each method has its merits and shortfalls, and combinations of techniques are not uncommon.

The 2 most commonly used selective approaches are abdominal stab wound exploration (combined with DPL) and serial clinical evaluation. Results from the available studies show comparable patient outcomes.

Modern approaches have succeeded in limiting the mortality due to anterior abdominal stab wounds to as low as 0-3.6%.[1,14 ]Selective approaches have achieved unnecessary laparotomy rates of less than 10%.[1,4,6,9,12,14 ]In abdominal stab wounds, the morbidity rate of a laparotomy with negative findings is in the range of 1.5-8%.[14,15,16 ]Regrettably, a limited number of injuries are still missed.

Abdominal stab wound exploration

Abdominal stab wound exploration allows for safe and immediate discharge of approximately 25% of patients with an abdominal stab wound. When performed by trained operators, this procedure is 100% sensitive.[9 ]If one considers patients who mandate laparotomy and those who have an exploration with negative findings, local wound exploration can guide an early, clear, and safe decision in more than half of patients who present with an anterior stab wound.[9 ]Unfortunately, positive local wound exploration findings carry a poor specificity for significant intra-abdominal injury. If all patients with positive abdominal exploration findings were to undergo laparotomy, more than 40% would do so unnecessarily.[1,9 ]Patients with positive local exploration findings, therefore, undergo DPL to further select those who are likely to have an intra-abdominal injury that requires surgical intervention. This strategy successfully reduces the number of nontherapeutic laparotomies.[17 ]

Diagnostic peritoneal lavage

DPL was initially developed as a tool to help assess for intra-abdominal injury in patients who had sustained blunt trauma. Its value in penetrating trauma is accepted, but its application is less clear. No consensus exists concerning what constitutes a positive result, and protocols vary from one institution to the next. Pre-lavage aspiration of 20 mL of blood is generally accepted as a positive result. The lavage fluid is assessed for red blood cells, white blood cells, bile, feces, and vegetable matter.

Some authors have also assessed various enzymes, including alkaline phosphatase (ALP) and amylase, with limited clinical value. Some authors have used a red blood cell count of greater than 100,000/μL and a white blood cell count of greater than 500/μL as the threshold. At these relatively high values, the incidence of missed injury increases and, consequently, even patients with negative lavage findings are further assessed and observed.[4,6,14 ]These cell count cutoff values are the same as those used for blunt trauma. When applied, these values achieve an accuracy rate of 90-91%.[4,18 ]

Isolated injuries to hollow organs often cause little bleeding. These injuries are commonly associated with lavage red blood cell counts of less than 100,000/μL or even of less than 10,000/μL. However, red cell counts of less than 1,000/μL are almost never associated with significant intra-abdominal injury.[4,9,19 ]

The white blood cell count threshold is not without problems, either. An elevated count raises suspicion of a hollow visceral injury. The intraperitoneal contents do not reliably produce a white cell response to injury until approximately 3 hours after the injury occurs. Hence, the timing of the lavage becomes important. Lavages performed soon after injury may reflect relatively low white cell counts despite significant injury. If significant delay occurs before the lavage is performed, even a simple breach of the peritoneum may produce a significantly raised white blood cell count.[4 ]

No threshold for DPL achieves 100% accuracy. The clinician must determine the relative weight of missed injury (false-negative findings) versus that of unnecessary laparotomy (false-positive findings). Up to 60% of visceral injuries involve the small bowel or colon.[1,20 ]Injuries to these organs are still the leading cause of morbidity and mortality in patients with abdominal stab wounds.[9 ]Surgeons are aware that the risk of morbidity and mortality of missed hollow visceral injury far outweighs that of unnecessary laparotomy; therefore, many have elected to lower their threshold for operative intervention. DPL is increasingly considered a quantitative assay that merely serves to provide further information to assist in decision-making and should no longer be used blindly with absolute cutoff values.

DPL may be unhelpful in patients with retroperitoneal injury. A lower threshold increases the sensitivity of the investigation but results in an increase in unnecessary surgery.[21 ]Demetriades achieved successful nonoperative management of patients with solid viscus injury with a protocol combining serial observation and CT scan.[22 ]DPL is not organ-specific. Oreskovich and Carrico quote a complication rate for DPL of less than 1%.[9 ]

Serial clinical evaluation

Serial clinical evaluation is a method used by many surgeons as a selective approach to abdominal stab wound management. Approximately 30% of patients with a significant abdominal injury have initial benign abdominal examination findings.[1 ]Furthermore, up to 10% of injuries are initially overlooked, even in the more advanced trauma centers.[23 ]These statistics clearly demonstrate the value of serial evaluation.

The length of hospital stay in patients whose injuries are managed conservatively varies among institutions. One study showed that no significant injuries were discovered in any patients who were asymptomatic after 12 hours of observation.[24 ]Most protocols, however, recommend evaluation of the patient over 24-72 hours.[12,25,26 ]The delay in laparotomy inherent in such an approach has not been associated with adverse outcome.[12 ]This is, possibly, because most severe injuries are obvious early. Degree of contamination is likely more important than the delay in surgery, provided the delay is not excessive. However, few would argue with the principle that the time taken to control contamination should be minimized. Martin et al found a 6-fold increase in complications in patients with colonic injury who were not operated on within 12 hours.[27 ]

Unfortunately, studies have also shown that 14-28% of patients without an injury that penetrates the peritoneum have misleading positive abdominal examination findings.[6,14,15 ]

Other methods of selection

Other methods of selection have been advocated, but few claim advantage over the 2 selective approaches discussed above.

Some authors advocate DPL alone without prior local wound exploration as particularly useful in patients who are difficult to assess clinically because of drugs or alcohol or who are to be anesthetized for another procedure. A study successfully used a red blood cell lavage count of less than 1,000/μL as a criterion for immediate discharge from the emergency department.[19 ]The authors claim that DPL is a simple procedure with few complications and that the complications, when they occur, are usually immediately evident. This view is certainly not shared by all.

Sinography (“stabogram”) and blind probing of wounds are unreliable procedures.[1,28 ]

Few authors advocate the use of laparoscopy in the management of anterior abdominal stab wounds. It may be useful as an adjunct in special circumstances. Laparoscopy is reliable when used to determine breach of the peritoneum or to assess potential diaphragm injuries in patients with wounds to the left upper quadrant or lower chest. It is unreliable in the assessment of hollow visceral injuries. A protocol of stab wound exploration followed by emergency department awake laparoscopy for equivocal cases has been studied, but it resulted in 31.3% of selected patients being exposed to the risks of unnecessary surgery.[29 ]At this stage, laparoscopy lacks sufficient therapeutic value to be used routinely in abdominal stab wounds.[30 ]

Ultrasonography, on its own, is inadequate as an investigation of anterior abdominal stab wounds and rarely aids in the management of these cases.[31 ]Focused abdominal sonography for trauma (FAST) scan has proved to be a reliable method of investigation in blunt abdominal trauma, especially when the scan is repeated.[32 ]This type of scan is less helpful in the assessment of patients with penetrating injury.[31,33 ]Low sensitivity and low negative predictive value limit its accuracy as an investigation. Positive FAST scan findings are useful predictors of significant intraperitoneal injury and, when performed early, can decrease the time to operation.[33 ]To confidently exclude significant intraperitoneal injury in patients with negative FAST scan findings, additional investigations are required.[33 ]

A small study of 35 patients has suggested a role for fascial ultrasonography to detect fascial penetration in anterior abdominal stab wounds.[34 ]As an investigation, fascial ultrasonography had a specificity and positive predictive value of 100%. Positive fascial ultrasonographic findings rule out the need for an abdominal stab wound exploration. Unfortunately, even in more experienced hands, fascial ultrasonography had a sensitivity of only 73%. The resultant drawback, therefore, is that negative fascial ultrasonographic findings do not adequately exclude an intra-abdominal injury, which requires further investigation or observation. Further assessment of the use of fascial ultrasonography may be justified.

Despite the instrumental role of CT scan in the assessment of penetrating flank and back wounds, it has traditionally been of little help with anterior abdominal wounds. The technology has not adequately revealed hollow visceral and diaphragm injuries.[35 ]Interestingly, the presence of free intraperitoneal air has poor specificity for intra-abdominal organ injury. Air can track through a defect in the abdominal wall and enter the peritoneal cavity. As part of a prospective study of 651 patients with abdominal stab wounds, 18 patients with free air under the diaphragm on plain radiograph were managed conservatively by method of serial examination. Only 2 of these patients went on to laparotomy, and no adverse outcomes were reported in the other 16 patients.[12 ]

Further developments

Further trials (or, perhaps, technology) may provide the next development in anterior abdominal stab wound management. No meaningful change has occurred in decades in the suggested management of this important and growing group of patients. No single investigation is likely to provide all the information necessary to accurately determine which patients are likely to have injuries that require surgical intervention. The combination of physical examination and other investigations has allowed a reduction in unnecessary intervention.[37 ]

A multidisciplinary working party recently developed evidence-based guidelines for the management of haemodynamically stable patients with stab wounds to the anterior abdomen. They conducted a systematic review of the available literature and recommended the use of abdominal stab wound exploration.[38 ]

For now, abdominal stab wound exploration remains a valid and effective tool that allows safe and early discharge of a significant number of patients. It is also valuable as a first step in a process that limits the time to decision-making in the management of asymptomatic patients with anterior abdominal stab wounds.

Multimedia

Media file 1: Flow chart illustrating the management options in patients with a stab wound to the anterior abdomen. Red arrows highlight an approach that favors abdominal stab wound exploration.

Media file 2: Transverse section of the anterior abdominal wall above the arcuate line.

Media file 3: Transverse section of the anterior abdominal wall below the arcuate line.

Media file 4: Boundaries of the anterior abdominal wall.

Media file 5: Stab wound to the anterior abdomen.

Media file 6: Equipment required for an abdominal stab wound exploration.

Media file 7: Sterile field.

Media file 8: Anesthetize the wound.

Media file 9: Midline wound: Extend vertically.

Media file 10: Lateral wound: Extend horizontally.

Media file 11: Visualize depths of the wound and maintain hemostasis.

Media file 12: Explore under direct vision.

Media file 13: Nonpenetrating wound: External oblique muscle intact in base of wound.

Media file 14: Penetrating midline wound.

Media file 15: Penetrating lateral wound. (The exploration of this wound clearly determined that the stomach had been penetrated. Therefore, the patient did not require diagnostic peritoneal lavage [DPL], as laparotomy was already indicated. During laparotomy, a hole in the stomach and 2 holes in the small bowel were repaired. The patient had an uneventful postoperative course and was discharged from the hospital 3 days later.)

Media file 16: Suture wound in layers. (This patient sustained a nonpenetrating stab wound to the abdomen. After the wound was repaired, the patient was discharged from the emergency department, and routine follow-up wound care was arranged with the local clinic.)

References

Hannah Swart, Switch Design, South Africa, for the illustrations.

Johannesburg Hospital Trauma Unit, for assistance in obtaining material for the article.

Further Reading

Cayton CG, Nassoura ZE. Abdomen. In: Ivatury RR, Cayton CG, editors. Textbook of Penetrating Trauma. 1st ed. Baltimore, Md: Williams & Wilkins, 1996:281-299.

Kirby R, Viswanathan S, Jiang R. Diagnostic and Therapeutic techniques. In: Sherry E, Trieu L, Templeton J, editors. Trauma. 1st ed. New York: Oxford University Press, 2003. p.715-716.

Back and flank wounds

Coppa GF. Back and Flank. In: Ivatury RR, Cayton CG, eds. Textbook of Penetrating Trauma. 1st ed. Baltimore, Md: Williams & Wilkins, 1996:300-308.

Diagnostic peritoneal lavage

Marx J. Diagnostic Peritoneal Lavage. In: Ivatury RR, Cayton CG, editors. Textbook of Penetrating Trauma. 1st ed. Baltimore, Md: Williams & Wilkins, 1996:335-343.

Wilson RF, Walt AJ. General Considerations in Abdominal Trauma. In: Wilson RF, Walt AJ. Management of Trauma: Pitfalls and Practice. 2nd ed. Baltimore, Md: Williams & Wilkins; 1996:411-431/20.

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