Penetrating Abdominal Trauma* 34 Avery B

Penetrating Abdominal Trauma* 34 Avery B. Nathens

“It is absolutely necessary for a surgeon to search the wounds himself, which were not drest by him at first, in order to discover their nature and know their extent.” (A. Belloste, 1701)

Among many trauma surgeons,decision-making in patients with penetrating trauma is considered much easier than that in blunt abdominal trauma.The princi- pal reason for this difference is that the clinical exam is not clouded by an altered sensorium due to head injury and the source of blood loss in the unstable patient is usually localized to the abdomen. These factors make an expensive, time-consum- ing series of radiologic investigations unnecessary. In fact, with the exceptions described below, there is no role for imaging studies in patients with penetrating abdominal injuries.

Avoid Unnecessary Laparotomies

The goal is to operate on patients in a timely fashion without an excess rate of unnecessary operations. Many surgeons distinguish a negative laparotomy from a non-therapeutic one.A negative laparotomy refers to an operation where no injury is identified, whereas a non-therapeutic laparotomy refers to the situation where an injury is identified but requires no surgical intervention.For example,an operation where a non-bleeding stab wound to the liver is identified would be considered a non-therapeutic laparotomy. However, I contend that there is no need to discrimi- nate between the two – in either case the patient experiences the cost and conse- quences of an unnecessary procedure without any benefit.

Stab versus Gunshot Wounds

The approach to patients with gunshot wounds to the abdomen differs significantly from that of stab wounds (or other impalements). The reason for a different approach is that almost every transabdominal gunshot wound requires an operation

* A comment by the Editors is found at the end of the chapter. 298 Avery B. Nathens

and in almost all cases this operation will identify injuries in need of surgical repair. The yield is far lower for stab wounds, so most (smart) surgeons use a selective approach to guide the need for operation.However,as surgeons become more com- fortable with selective non-operative management of stab wounds, some have applied a similar approach to patients with gunshot wounds.

Stab Wounds to the Abdomen

All decision-making in patients with a stab wound to the abdomen begins with the assessment of vital signs.A laparotomy is indicated in all patients with unstable vital signs – either hypotension or persistent tachycardia if the latter is presumed to be due to hemorrhage. In patients with upper abdominal or thoracoabdominal stab wounds (i.e., between the nipples and the costal margins), a chest X-ray is warranted to rule out a significant hemothorax or pneumothorax, which might represent an immediate threat to life and/or alter the surgical plan. It is also important to consider the potential for pericardial tamponade due to a ventricular laceration in patients with wounds to the epigastrium. There is usually neither time nor need for any imaging study to diagnose tamponade.It will become evident at laparotomy when the trajectory of the wound is cephalad to or through the diaphragm. In this setting, a rapid pericardial window and conversion to sternotomy is indicated. If the patient is hemodynamically normal,the next important determinant is evidence of peritonitis, a clinical finding being suggestive of an injury to a hollow viscus (e.g., stomach, small bowel, or colon). The diagnosis of peritonitis is not straightforward,as many of these patients have local pain at the site of penetration. If generalized peritonitis is present, a laparotomy is clearly indicated. Aside from generalized peritonitis and hemodynamic instability, the only other indication for laparotomy at initial presentation is a retained stabbing instrument. As the instrument might be tamponading a significant arterial or venous injury, these should be removed under direct vision in the operating room. Occasionally,peritoneal penetration manifests as omental or bowel evisceration through the stab wound. These patients have a high likelihood of hollow viscus injury and should undergo operation to safely reduce the herniated contents, rule out other injuries and properly close the fascia.

The “Asymptomatic” Patient

Decision-making in the relatively asymptomatic patient without the indications for operation listed above is more complicated.The first question to be answer- 34 Penetrating Abdominal Trauma 299 ed is whether or not there is penetration of the peritoneum. Of all stab wounds to the abdomen one-third do not have peritoneal penetration and another third have peritoneal penetration without any significant abdominal injury. Wound exploration using local anesthetic and appropriate lighting usually allows one to determine whether the peritoneum has been violated.

If it can be established with certainty that there is no peritoneal penetration, the patient can be safely discharged from the emergency department

Peritoneal penetration confirmed by wound exploration presents two options:  The first approach, and one practiced safely by many experienced clinicians, is admission to an observation unit with serial examinations. This is an active process requiring serial hematocrits, hourly monitoring of vital signs, and repeat examination of the abdomen at intervals no greater than every 4 hours for 24 hours. Any clinical deterioration or change in the abdominal examination warrants a laparotomy.  In the second approach, practiced in some institutions, clinicians employ diagnostic peritoneal lavage to provide an earlier diagnosis of intra-abdominal injury. The red blood cell threshold typically used as an indication for laparotomy is much lower than that for blunt trauma,usually in the range of 1,000 to 10,000 cells/dl.The lower the threshold, the higher the rate of negative or non-therapeutic laparotomy. The high rate of negative laparotomy represents the single major disadvantage to this approach. By contrast, the rate of negative laparotomy in those who fail serial examination is, as one would expect, much lower.

Adjunctive Imaging

In patients with stab wounds to the back or flank,the risk of abdominal injuries is quite low. However, the retroperitoneal colon, duodenum, kidneys, ureter and major vascular structures are all at risk.Injuries to the retroperitoneal colon or duodenum will typically manifest later than intraperitoneal injuries, and are associated with significant morbidity.On the other hand,stab wounds to the kidneys might not require operation at all.Given the potential morbidity of a significantly delayed diagnosis of a retroperitoneal injury, a CT scan of the abdomen with intravenous, oral, and rectal contrast to opacify the entire colon should be performed to allow earlier diagnosis of injuries requiring repair.This approach is indicated only if there is no other reason to operate. 300 Avery B. Nathens

The Diaphragm

There is a lot of controversy regarding the natural history of stab wounds to the diaphragm. It is likely that many of these remain silent with no adverse con- sequences over the patient’s lifetime.Alternatively, there might be a risk of chronic diaphragmatic herniation with the potential for late complications such as strang- ulation requiring a more difficult repair. For this reason, diagnostic laparoscopy (or thoracoscopy) should be performed to evaluate fully the diaphragm in patients with thoracoabdominal stab wounds who lack other indications for operation. If there is an injury to the diaphragm, we convert to laparotomy to rule out a hollow viscus injury, as the sensitivity of laparoscopy in identifying such injuries is poor. At laparotomy, a thorough exploration is carried out and all injuries repaired. If at laparoscopy for a right thoracoabdominal stab wound, a non-bleeding liver laceration is identified, it is often possible to repair the diaphragmatic laceration laparo- scopically and avoid a laparotomy entirely.

Gunshot Wounds to the Abdomen

Traditionally, the standard of care for a gunshot wound to the abdomen was a laparotomy. The rationale for this approach was two-fold. First, the incidence of injuries requiring repair was considered high enough that the rate of negative laparotomy was minimal.Secondly,the morbidity associated with a negative laparotomy was considered trivial.

Non-operative Management

With higher rates of negative laparotomy in the civilian population (with less destructive munitions) and a greater understanding that a negative laparotomy is associated with a real rate of complications and costs, some trauma surgeons are beginning to re-evaluate this. There is an increasing trend toward selective non- operative management of stable patients without evidence of peritonitis. These patients undergo active observation as that described above for stab wounds. If the patients are well selected, approximately one-third might get by without a laparotomy. Those who fail non-operative management do so early, typically in the first 4 hours. Successful non-operative management requires experience, good clinical judgment and,not infrequently,a CT scan of the abdomen to help define the trajectory of the bullet. Certain clinical settings are better suited to selective management. For example,a gunshot wound to the right thoracoabdominal region (between the right 34 Penetrating Abdominal Trauma 301 nipple and right costal margin) typically injures the liver and diaphragm.As the liver will prevent diaphragmatic herniation, there might be very little to be gained by operation in the stable patient. However, as for stab wounds, the natural history of these diaphragmatic injuries is unknown and might be associated with significant later morbidity.Another scenario appropriate for selective non-operative management is a low transpelvic gunshot wound. These gunshot wounds might injure the rectum,bladder and iliac vessels.If the trajectory of the bullet can be determined to be extraperitoneal and injury to these structures ruled out using a combination of sigmoidoscopy, CT scan and cystography, then non-operative management might be appropriate.A diagnostic peritoneal lavage might be necessary to rule out intraperitoneal penetration if this cannot be excluded with certainty based on CT scan.

As for stab wounds,successful non-operative management is an active process. If resources or manpower do not allow for serial re-evaluation and close monitoring, then a policy of routine laparotomy for gunshot wounds to the abdomen should be adhered to.

Conduct of the Laparotomy

The patient should be prepped from the neck to the knees so that the surgeon has access to all intrathoracic structures as well as vessels in the groin.A full-length midline incision provides access to the entire abdomen and should be the incision of choice if the patient is unstable. It is not appropriate to spend excessive amounts of time trying to get better exposure while trying to control bleeding. Smaller inci- sions might be appropriate for stab wounds or gunshot wounds in the stable patient. If there is a significant hemoperitoneum, all four quadrants should be packed off – both to tamponade ongoing bleeding and to allow the anesthesiologist time to catch up with restoration of intravascular volume.The packs are then removed sequential- ly, starting with the packs in the quadrants where there is least likely to be ongoing bleeding. Once the source(s) of bleeding have been isolated and controlled, a more thorough evaluation of the abdomen should be done. It is critical to create a mental image of the trajectory of the bullet (or stabbing instrument) so that a thorough evaluation of all structures in the path can be carried out. While doing this bear in mind that the patient is likely to have been in a contorted position attempting to avoid injury and the result may be that individual intraperitoneal injuries may be anatomically widely separated. When evaluating injuries to hollow organs, there is almost always an even number of holes. Rarely, this rule is violated when an injury is tangential to the bowel or the missile fragment lodges within the bowel lumen. Diligence is required, particularly with stab wounds to the bowel as these might be 302 Avery B. Nathens

very subtle. There is no sense in subjecting the patient to an operation only to miss an injury. To review exploration of the abdomen consult also > Chap. 11. Management of specific organ injuries is outlined in > Chap. 35.

Summary

 Stab wounds to the abdomen should be managed selectively, avoiding a large number of negative laparotomies (> Fig. 34.1).  If local wound exploration demonstrates no peritoneal penetration,the patient can be discharged.  If the patient is stable, without peritonitis, or bowel or omental evisceration, they should be observed with serial abdominal exams,hemoglobin,and white blood cell count.Any change in clinical status for the worse should mandate a laparotomy.  Diaphragmatic injuries should be ruled out using laparoscopy in patients with thoracoabdominal stab wounds without other indications for laparotomy.

Fig. 34.1. Algorithm for the management of stab wounds to the abdomen (see text for details) 34 Penetrating Abdominal Trauma 303

 Imaging studies have no role,except for patients with stab wounds to the back or flank, where CT scan using intravenous, oral and rectal contrast to opacify the entire colon will help identify the relatively few patients who will require operation.  The selective approach is not well accepted for gunshot wounds, so it is my preference to subject these patients to laparotomy given the high likelihood of intra-abdominal injuries requiring operative repair.

“It is highly desirable that anyone engaged in war surgery should keep his idea fluid and so be ready to abandon methods which prove unsatisfactory in favor of others which, at first, may appear revolutionary and even not free from inherent danger.”(H.H.Sampson, 1940)

Editorial Comment

Dr. Nathens provides a balanced approach to the patient with penetrating abdominal injuries – not too aggressive, not too conservative and extremely safe. But wherever you practice and whatever your experience do understand that two- thirds of stab wounds to the abdomen do not need surgery.Shock and/or peritonitis indicate a laparotomy – when absent you may take Dr.Nathens’s advice and explore the wound to detect peritoneal penetration and discharge home those with proven superficial wounds. All the others should be subjected to “selective conservatism” during which the abdomen is frequently re-evaluated at intervals of 1–3 hours, preferably by the same surgeon. The stab wound and its surroundings are usually tender. It is useful to mark with a pen the tender zone around the laceration to monitor any subsequent spread of the tenderness beyond the marked area. Even if you feel that the patient may object to being treated as a drawing table, the underlying principle is to look for evidence of tenderness away from the stab wound. Please do us a favor and do not subject patients with stab wounds to the anterior abdominal wall to CT and diagnostic laparoscopy. People who perform these unnecessary investigations do it because they lack clinical skills and experience. In our hands, and those of others, the clinical approach has proven reliable and safe. Do you want to be known as a seasoned clinician? Practice as one. Laparoscopy or thoracoscopy to identify diaphragmatic injuries seems sen- sible if the wound is left-sided.We remain skeptical of the benefits of active management of lesions over the right hepatic lobe; it seems unlikely that troublesome hernias will occur in this situation. 304 Avery B. Nathens

Fig. 34.2. “Let’s be conservative!”

Whether you want to explore all abdominal gunshot wounds, including those with an innocent looking abdomen – denoting absence of peritoneal penetration or a tangential abdominal wall trajectory of the bullet – is up to you.However,the vital signs and abdominal examination in most of these patients will declare that a prompt laparotomy should be performed. When the patient is hemodynamically stable and his abdomen is clinically “innocent” we see no reason to treat him other than with the selective conservatism outlined above (> Fig. 34.2).

“Failure to promptly recognize and treat simple life-threatening injuries is the tragedy of trauma,not the inability to handle the catastrophic or complicated injury.” (F.William Blaisdell)