Introduction

The approach to patients who have sustained colon trauma has changed dramatically over the last several decades. This has been associated with a significant improvement in colon-related mortality from approximately 60% during World War I to 40% during World War II, 10% during the Vietnam War and even lower in the current era. Colon-related morbidity, however, still remains high and in most prospective studies the abdominal sepsis rate is approximately 20% (Table 33-1).^{1,2,3,4,5,6,7} In patients with destructive colon injuries, high Penetrating Abdominal Trauma Index (PATI), or multiple blood transfusions the incidence of intra-abdominal sepsis has been reported to be as high as 27%.^8,9

Epidemiology

In the United States, the overall incidence of blunt and penetrating trauma remains similar⁷; however, this will vary depending on the center’s incoming demographic. In general, blunt trauma patients can be expected to be older, have a higher total burden of injury and endure longer hospital stays with a higher mortality and complication rate.⁷ In abdominal gunshot wounds the colon is the second most commonly injured organ after the small bowel and is involved in approximately 27% of cases undergoing laparotomy.^10,11 In anterior abdominal stab wounds the colon is the third most commonly injured organ after the liver and small bowel and is found in approximately 18% of patients undergoing laparotomy. In posterior stab wounds the colon is the most commonly injured organ and is seen in about 20% of patients undergoing laparotomy.¹² The right colon is most frequently injured after blunt force trauma⁷ whereas the transverse colon is the most commonly injured segment after gunshot wounds and the left colon the most commonly injured segment after stab wounds.

Stab wounds or low-velocity civilian gunshot wounds usually cause limited damage and most are amenable to debridement and primary repair (Fig. 33-1). High-velocity penetrating injuries, such as in war-related trauma, cause major tissue damage and almost always require colon resection (Fig. 33-2).

Blunt trauma to the colon occurs in approximately 10.6% of patients undergoing laparotomy.¹³ Most of these injuries are superficial and only about a third will have full-thickness colon perforations.¹³ Motor vehicle associated trauma is the most common cause of blunt colon injury. This can result in rapid deceleration with mesenteric tearing and ischemic necrosis of the colon (Fig. 33-3). Transient formation of a closed loop and blowout perforation may also occur. Seatbelt use increases the risk of hollow viscus perforations. The presence of a seatbelt mark sign should increase the index of suspicion for hollow viscus injury. In rare cases a colonic wall hematoma or contusion may result in delayed perforation several days after the injury.

In blast injuries such as in war or terror-related explosions, hollow viscera are more susceptible to injury than solid organs (Fig. 33-4). The blast wave is more likely to cause colon rupture than any other intra-abdominal organ.¹⁴ Penetrating shrapnel secondary to the blast is often the direct cause of the hollow viscus injury.¹⁴

Diagnosis

In patients with penetrating abdominal trauma undergoing immediate laparotomy, the diagnosis of colon injury is made intraoperatively. For those selected to undergo a trial of nonoperative management, the diagnosis is based on CT scan evaluation with IV contrast, which is particularly useful for gunshot wounds, and serial clinical examination.¹⁵ Other investigations, such as ultrasound, diagnostic peritoneal lavage, or laparoscopy, have little or no role in the contemporary evaluation of suspected colon injuries.

The preoperative diagnosis of colon injury following blunt trauma can be difficult, especially in unevaluable patients. The diagnosis can be suspected on CT, which remains the diagnostic modality of choice, by the presence of free gas, unexplained free peritoneal fluid, or a thickened colonic wall (Fig. 33-5). Because of the imperfect sensitivity of CT, the diagnosis may be delayed by many days with catastrophic consequences. Finally, a rectal examination may show blood in the stool, especially in cases with distal colon or rectal injuries however the rectal examination lacks sensitivity¹⁶ and therefore cannot be relied upon to rule out an injury.

Intraoperatively, especially for penetrating trauma due to stab wounds and shotgun wounds where the injuries can be very small, every paracolic hematoma should be explored and the underlying colon should be evaluated carefully. Failure to adhere to this important surgical principle is a serious error with medical and legal implications. For most gunshot wounds, the injuries tend to be large and are relatively easily diagnosed in the operating room. With blunt trauma, however, the findings may be subtle and all hematomas should be evaluated completely. Careful examination of the mesentery is also warranted. Any defects should be closed to prevent herniation after ensuring the viability of the colon segment associated with the defect.

Colon Injury Scale

The American Association for the Surgery of Trauma (AAST) developed a grading system for colon injuries that is useful in predicting complications and comparing therapeutic interventions. The AAST Colon Injury Scale is shown in Table 33-2.¹⁷

Operative Management

Historical Perspective

The first guidelines regarding the management of colon injuries were published by the US Surgeon General and mandated colostomy for all colon wounds. This unusual directive was initiated because of the exceedingly high mortality associated with colorectal injuries, in excess of 50%,^18,19 during the early years of World War II. Although these guidelines were not based on any scientific evidence, they were credited for the improved outcomes seen in the last years of the war. However, during this period many other major advances such as faster evacuation from the battlefield, improved resuscitation, and introduction of penicillin and sulfadiazine may have contributed to the reduction in mortality. The policy of mandatory colostomy remained the unchallenged standard of care until late 1970s. Stone and Fabian reported the first major scientific challenge of this policy in 1979.²⁰ A prospective randomized study, which excluded patients with hypotension, multiple associated injuries, destructive colon injuries, and delayed operations, concluded that primary repair was associated with fewer complications than colostomy.

The validity of these “standard” contraindications for primary repair or resection and anastomosis was challenged in subsequent studies. New prospective randomized studies with no exclusion criteria demonstrated the safety of primary repair for nondestructive colon injuries. By the 1990s and 2000s primary repair gained widespread acceptance and the role of colostomy was challenged, even in cases with these perceived risk factors. Today, the vast majority of injuries are primarily repaired however, in specific cases where there is a highly destructive blast injury, or staged treatment under austere combat conditions or where the patient is profoundly malnourished or has immunosuppression due to HIV or chemotherapy, diversion may be warranted malnourished or immunosupressed.

Contemporary Management of Nondestructive Colon Injuries

Nondestructive injuries include those involving less than 50% of the bowel wall and without devascularization. There is now sufficient class I evidence supporting primary repair in all nondestructive colon injuries irrespective of risk factors. Chappuis² in a randomized study of 56 patients with no exclusion criteria concluded that primary repair should be considered in all colon injuries irrespective of the presence of risk factors. In a subsequent study in 1995, Sasaki²¹ randomized 71 patients with colon injuries to either primary repair or diversion, again without any exclusion criteria. The overall complication rate was 19% in the primary repair group and 36% in the diversion group. In addition, the complication rate associated with colostomy closure was 7%. The study concluded that primary repair should be performed in all civilian penetrating colon injuries irrespective of any associated risk factors.

In another prospective randomized study in 1996, Gonzalez⁵ randomized 109 patients with penetrating colon injuries to primary repair or diversion. The sepsis-related complication rate was 20% in the primary repair group and 25% in the diversion group. The authors continued their study and the series increased to 181 patients.²² They concluded again that all civilian penetrating colon injuries should be primarily repaired.

Overall, a collective review of all published prospective randomized studies identified 160 patients (Table 33-3) with primary repair and 143 patients treated with diversion. The abdominal sepsis complication rate was 13.1% and 21.7%, respectively. In addition, numerous prospective observational studies also support routine primary repair in nondestructive injuries.^1,3,4,22 In conclusion, there is sufficient class I and II data to support the routine primary repair of all nondestructive colon injuries, irrespective of the presence or absence of risk factors.

Despite the available scientific evidence, many surgeons still consider colostomy as the safest procedure in high-risk colon injuries. In a survey of 317 Canadian surgeons in 1996, 75% of them chose colostomy in low-velocity gunshot wounds to the colon.²³ In another survey in 1998, of 342 American trauma surgeons, members of the AAST, a colostomy was the procedure of choice in 3% of injuries with minimal spillage, in 43% of injuries with gross spillage, in 18% of injuries involving greater than 50% of the colon wall, and in 33% of cases with colon transection.²⁴ Clearly old habits still play a significant role in modern surgical practice.

Contemporary Management of Destructive Colon Injuries

Destructive colon injuries include those with loss of more than 50% of the bowel wall circumference or with devascularization (see Fig. 33-2) and require a segmental colonic resection. Destructive injuries were traditionally managed with diversion because of the perceived high risk for intra-abdominal sepsis. Small prospective studies in the 1990s suggested that primary anastomosis may be safe. Collectively, these studies included only 36 patients with colon resection and anastomosis. The incidence of anastomotic leak was 2.5% and no deaths occurred. These studies concluded that primary anastomosis is the procedure of choice irrespective of the presence of any risk factors for abdominal complications.^2,5,21 However, a prospective observational study with 25 patients treated by resection and anastomosis reported two fatal anastomotic leaks (8%) directly attributed to suture line breakdown.⁸ The study concluded that some high-risk patients (PATI >25 or ≥6 U of blood transfusions or delayed operation) with destructive colon injuries may benefit from diversion. The study included very few patients who were diverted, making any comparison with the primary anastomosis group impossible.

There were also two retrospective studies which included only destructive colon injuries requiring resection. In an analysis of 43 patients who were managed by resection and anastomosis Stewart²⁵ reported an overall anastomotic leak rate of 14%. However, in the subgroup of patients with blood transfusion greater than 6 U the leak rate was 33%. The study suggested that diversion should be considered in patients receiving massive blood transfusions or in the presence of underlying medical illness. In another retrospective study of 140 patients with destructive colon injuries requiring resection Murray²⁶ reported similar intra-abdominal sepsis rates with primary anastomosis or diversion. Univariate analysis identified Abdominal Trauma Index greater than or equal to 25 or hypotension in the emergency room to be associated with increased risk of anastomotic leak. The study suggested that diversion be considered in these high-risk subgroups of patients.

In summary, the available prospective randomized data to this point, which included only a small number of cases, recommended resection with anastomosis irrespective of risk factors. Two larger retrospective studies suggested that diversion should be considered in selected patients with PATI greater than or equal to 25, multiple blood transfusions, or associated medical comorbidities.^25,26

In order to address these limitations, the AAST sponsored a prospective multicenter study to evaluate the safety of primary anastomosis or diversion and identify independent risk factors for colon-related complications in patients with penetrating destructive colon injuries.⁶ The study included 297 patients with penetrating colon injuries requiring resection who survived at least 72 hours. Rectal injuries were excluded. The overall colon-related mortality was 1.3% (four deaths) and all deaths occurred in the diversion group (P = .01). The most common abdominal complication was an intra-abdominal abscess (19% of patients) followed by fascia dehiscence (9%). The incidence of anastomotic leak was 6.6% and no deaths occurred in the group with an anastomosis. Multivariate analysis identified severe fecal contamination, greater than or equal to 4 U of blood transfusions within the first 24 hours, and inappropriate antibiotic prophylaxis as independent risk factors for abdominal complications. In the presence of all three of these risk factors, the incidence of abdominal complications was approximately 60%, in the presence of two factors the complication rate was 34%, in the presence of only one factor the rate was approximately 20%, and with no risk factors it was 13%. The method of colon management (anastomosis or diversion), delay in operation, shock at admission, site of colon injury, PATI greater than 25, ISS greater than 20, or associated intra-abdominal injuries were not found to be independent risk factors for developing a complication. The study also compared colon-related outcomes in high-risk patients (hypotension at admission, blood transfusions >6 U, delay of operation >6 hours, severe peritoneal contamination, or PATI >25) after primary anastomosis or colostomy. These risk factors have been suggested by many surgeons as an indication for diversion. The colon-related mortality in this high-risk group was 4.5% (4 of 88 patients) for the colostomy group and zero in the 121 patients who underwent primary anastomosis (P = .03). The adjusted relative risk of abdominal septic complications was similar when comparing colostomy to primary anastomosis, in both the low- and high-risk patients (Table 33-4). There was a trend toward longer ICU and hospital stay in the colostomy group. The study concluded that because “colon diversion is associated with worse quality of life and requires an additional operation for closure, colon injuries requiring resection should be managed by primary repair, irrespective of risk factors.”⁶ As mentioned earlier in this section, there may be some notable exceptions to the widely accepted practice of primary anastomosis. For example, the patient who sustains a destructive injury secondary to a blast mechanism, such as that seen after an improvised explosive device. In these patients, the more liberal utilization of diversion may be warranted.²⁷