INCIDENCE AND MECHANISM

Mechanisms of colon and rectal injuries can be classified as direct penetration of the bowel wall by a foreign body as with stab or gunshot wounds, high-pressure blowout of the bowel wall as occurs in blunt trauma, or devascularization injury secondary to avulsion of the supporting mesentery. The vast majority of colon injuries are caused by penetrating trauma. Firearms account for 75%–90% of penetrating colon injuries. The colon is second only to the small bowel in the frequency of organs injured in penetrating trauma. The high incidence of colon injuries in penetrating trauma relative to other organs is a reflection of the size and distribution of the colon within the abdominal cavity. In contrast, blunt colon injuries are rare, occurring in less than 5% of patients with abdominal injuries. Most occur following high-energy motor vehicle crashes and present as blowout disruptions of colonic wall or mesenteric avulsions. Approximately 80% of rectal injuries are caused by firearms, 10% by blunt trauma, 6% by transanal or impalement injuries, and 3% by transabdominal stab wounds.

DIAGNOSIS

Colon injuries are most often diagnosed during operative exploration. Although it is rare to make an organ-specific diagnosis preoperatively, free intraperitoneal air may occasionally be seen on chest x-ray or abdominal CT scan. Blood or a positive occult hemoglobin test on digital rectal examination may also be seen. Suspicion of enteric injury should be raised in all patients with evidence of fever, tachycardia, peritonitis, and leukocytosis. Computed tomography (CT) scan evidence of intra-abdominal fluid in the absence of solid organ injury warrants further investigation, usually by diagnostic peritoneal lavage. A triple-contrast CT scan may be helpful in patients who have penetrating flank injuries with no clear evidence of intraperitoneal injury.

Blunt colonic injuries are evenly distributed around the colon and usually present as large blowout disruptions of the colon wall or avulsion injuries where the mesocolon is stripped from the adjacent colon. Although penetrating colon injuries are usually obvious, missed injuries are often the result of small-caliber gunshot wounds or stab wounds to areas that are difficult to examine, such as the splenic flexure and rectosigmoid junction. If a perforation is not obvious, feculent odor, hematoma, or mesenteric staining may suggest an area that requires further evaluation. The suspicious area should be completely mobilized. Division of one or two terminal mesenteric vessels may be necessary to adequately evaluate potential injuries to the mesenteric border. A final diagnostic maneuver is to create a closed loop of colon by proximal and distal manual compression and gently milk the bowel contents toward the suspected injury. The extrusion of fecal material or gas is diagnostic, while its absence effectively rules out colonic injury.

All patients with truncal stab and gunshot wounds, or impalements of the lower abdomen, buttocks, perineum, or upper thighs, and any patient with a history of anal manipulation and lower abdominal or pelvic pain should be suspected of having a rectal injury. Evaluation begins with a digital rectal examination, where the presence of gross or occult blood should trigger further evaluation. However, it is important to note that a negative digital rectal examination does not rule out a rectal injury. Rigid proctoscopy should be performed in all patients with suspected rectal injury. Unstable patients who have undergone laparotomy for hemorrhage control, should have the abdomen temporarily closed and the patient should be repositioned for proctoscopy. Palpation or visualization of a perforation is definitive evidence of an injury. However, intraluminal blood or a submucosal hematoma is often the only evidence of rectal injury. In such cases with distal rectal injuries, transabdominal exploration and rectal mobilization does not improve the chance of definitive diagnosis and may increase the chance of iatrogenic vascular, urologic, or neurologic injury. Therefore, these patients should be treated in the same manner as patients with confirmed rectal injuries.

ANATOMIC LOCATION AND INJURY GRADING

The colon begins at the ileocecal valve and continues to the rectosigmoid junction. Blood is supplied via the ileocolic, right, and middle colic branches of the superior mesenteric artery and the left colic and sigmoidal branches of the inferior mesenteric artery. Venous drainage is via the mesenteric plexus to the superior and inferior mesenteric veins that empty into the portal vein. The rectum begins at the rectosigmoid junction and ends at the dentate line in the anal canal. Blood is supplied by the superior hemorrhoidal branch of the inferior mesenteric artery and the middle and inferior hemorrhoidal branches of the internal iliac or internal pudendal arteries. Venous drainage of the rectum follows the arteries with the superior hemorrhoidal vein draining into the portal system and the middle and inferior hemorrhoidal veins drain via the internal iliac veins.

The Organ Injury Scaling Committee of the American Association of the Surgery of Trauma has developed colon and rectal injury scales that facilitate comparison of injuries between patients and facilities and helps identify patients at high risk for postoperative complications (Tables 1 and 2).

Table 1 AAST Colon Injury Grading

Note: Advance one grade for multiple injuries up to grade III.

Modified from Organ Injury Scaling Committee of the American Association of the Surgery of Trauma.

Table 2 AAST Rectal Injury Grading

Note: Advance one grade for multiple injuries to the same organ.

Modified from Organ Injury Scaling Committee of the American Association of the Surgery of Trauma.

SURGICAL MANAGEMENT

The current management strategies for colon and rectal injuries have been scientifically established in recent decades in civilian trauma centers where operations are generally performed shortly after injury in patients who have been resuscitated and treated with antibiotics. There are two generally accepted surgical options for contemporary management of colon injuries: primary repair or colostomy. Primary repair, whether direct closure of a defect or segmental resection and primary anastomosis, implies that the initial surgical intervention is definitive and no further treatment is necessary. Colostomy options include proximal end colostomy or ileostomy with distal mucous fistula or distal closure (Hartman’s procedure), loop colostomy of the injured segment, and diverting colostomy proximal to suture repair.

Most authorities would agree that modern treatment of colon injuries is either by primary repair or colostomy. Although primary repair of all colon injuries in the nonmilitary setting is a desirable goal, it is not always possible. The key to successful management is patient selection based on the location and degree of injury and the physiologic state of the patient at the time of repair. For simple nondestructive injuries that do not require segmental resection (AAST CIS I–III), the treatment of choice is primary suture repair. Debridement is kept to a minimum except to remove grossly contaminated or ischemic tissue. We employ a single transverse closure using absorbable monofilament suture beginning a few millimeters from each end of the colostomy. Sutures are placed to gently oppose the seromuscular layer in a continuous Lembert fashion (Figure 1).

Figure 1 Primary repair of a nondestructive colon injury using a single-layer continuous suture. (Baylor College of Medicine.)

The choice between primary anastomosis and colostomy is more complex for destructive colon injuries. The first consideration is the physiologic state of the patient. A damage control approach should be strongly considered for patients with significant metabolic compromise. Critically injured patients with evidence of acidosis, coagulopathy, and hypothermia are at imminent risk of death. The damage control approach is founded on the principle that the metabolic status of the patient does not allow sufficient time to definitively repair all injuries. The immediate priority is to control bleeding and abdominal contamination, temporarily close the abdomen, and transport the patient to the intensive care unit for vigorous metabolic resuscitation, correction of coagulopathy, and rewarming. The most expeditious method to control fecal contamination is to resect the injured segment of colon using a GIA stapler and close the abdomen with an adhesive plastic sheet. Definitive management of the injury is then performed once the patient has been adequately resuscitated, usually within 24 hours.

Primary repair has been established as the optimal treatment of destructive colon injuries. Destructive injuries proximal to the middle colic artery are generally treated with a right colectomy and ileocolostomy. Ileocolostomy has proven to be a robust anastomosis under emergent conditions and the low associated leak rate justifies its use for almost all injuries proximal to the middle colic artery. Primary repair by lateral suture or segmental resection and colocolostomy is also the procedure of choice for destructive injuries distal to the middle colic artery. Several contemporary retrospective and prospective randomized studies have demonstrated that the results following primary repair are as good as or better than routine colostomy with respect to postoperative complications. These studies have also identified a number of risk factors for suture line failure that include blood loss, concomitant solid organ injury, fecal contamination, mechanism of injury, delayed repair, and patient age. An additional consideration is the subjective evaluation of the degree of bowel edema present at the time of anastomosis. The visceral edema that occurs in the setting of large-volume resuscitation makes the placement and tension of anastomotic sutures uncertain and healing unpredictable. Therefore, colostomy should be considered for injuries distal to the middle colic artery in the presence of significant bowel edema.

Although several methods have been described for creation of ileocolostomy and colocolostomy, we prefer the end-to-end, single-layer technique using absorbable monofilament suture (Figure 2). The suture line is started at the mesenteric border using a double-armed 3-0 polydiaxone suture. Sutures are then placed 3–4 mm from the cut edge of the bowel to include all layers but the mucosa. Each arm is advanced around the bowel and tied at the antimesenteric border resembling a vascular anastomosis. Disparity in bowel caliber can be solved by extension of the enterotomy on the smaller end along the antimesenteric border. The mesenteric defect is then closed with a continuous absorbable suture.

Figure 2 Resection and primary repair of a destructive colon injury using a single layer continuous suture to create an end-to-end anastomosis. (Baylor College of Medicine.)

Destructive colon injuries distal to the middle colic artery in patients with multiple risk factors for suture line failure should be treated with colostomy. The damaged section of the colon is resected using a GIA stapler and the proximal end of the colon used for the colostomy. The key technical aspects of colostomy are to ensure that the clamped end of the colon reaches the skin level with no tension, that the end of the colon has an adequate blood supply, and that the colostomy is immediately matured with sutures between the mucosa and the skin without tension. The distal end of the defunctionalized colon is left closed with staples. Treatment of the distal colon segment with mucous fistula is avoided because it is time consuming, is of no additional benefit, adds the potential complications of a second stoma, and adds difficulty to subsequent colostomy closure.

Rectal injuries identified either preoperatively or during abdominal exploration should be repaired. As noted previously, the only indication of a rectal injury may be the presence of intraluminal blood or a submucosal hematoma observed during rigid proctoscopy. Wounds to the extraperitoneal rectum with little or no loss of the rectal wall can be treated with colostomy and presacral drainage alone. Extensive dissection to definitively visualize distal rectal injuries should be avoided because of the potential for vascular, urologic, neurologic, or iatrogenic rectal injury. In such cases, the patient is treated as if a rectal injury is present with presacral drainage and proximal diversion (Figure 3). A curved incision is made posterior to the anus and the presacral space developed bluntly to the level of the sacrum. Ideally, Penrose drains are placed in proximity but not in contact with the injury. The drains are secured to the skin with silk sutures for better patient comfort and usually removed between 4 and 7 days postinjury. Although several methods for proximal diversion are described, it is essential that the chosen technique must completely divert the fecal stream from the rectal injury. We employ a loop colostomy located in the patient’s left lower quadrant using the sigmoid colon. The critical technical elements to ensure complete diversion are creating a longitudinal colotomy, maintaining the common wall or spur between the afferent and efferent limbs above the level of the skin, and maturing the stoma to the skin immediately. A loop colostomy created in this manner completely diverts the fecal stream.

Figure 3 Technique for presacral drainage and proximal diversion for treatment of occult or unrepaired distal colon injuries. (Baylor College of Medicine.)

Nondestructive rectal injuries that do not require resection based on intraoperative evaluation (AAST RIS I–III) are repaired primarily. These injuries are generally lacerations with minimal surrounding tissue destruction that are easily exposed and sutured. The location may be intraperitoneal or extraperitoneal and exposed after mobilization of the proximal rectum. The technique used is the same as that for primary repair of colon injuries using a running single layer of 3-0 polydiaxone suture. Placement of drains in the pelvis is not necessary and may increase the risk of fistula.

Extensive loss of the rectal wall or devascularizing injuries (AAST RIS IV and V) are best treated by resection of the rectum distal to the injury and proximal end colostomy. The rectum can be divided within a few centimeters of the anal verge with the aid of a TA stapler after mobilization of the distal rectum. In addition, the advent of the end to end circular stapling device has facilitated elective colostomy closure. This has proved to be a much safer approach to destructive colon injuries than primary repair.

MORBIDITY AND COMPLICATIONS MANAGEMENT

Intra-abdominal abscess is the most frequent septic complication following colon repair, occurring in 5%–15% of patients. Small abscesses of less than 2 cm often respond to intravenous antibiotic therapy and do not require drainage. Many intra-abdominal abscesses can be managed by image guided percutaneous drainage. Occasionally, percutaneous drainage reveals an underlying fistula. In such cases when the patient has no evidence of sepsis, the percutaneous drain is left in place until serial fustulograms demonstrate obliteration of the abscess cavity. Once this occurs, the drain is slowly removed. Larger intra-abdominal abscess that are inaccessible to percutaneous drainage and those associated with sepsis require operative drainage.

Suture line failure and fecal fistula may occur regardless of the treatment method chosen and is observed in 1%–8% of patients. Fistulas that extend to the incision are often associated with intra-abdominal abscesses and evidence of sepsis. A fistulogram should also be performed to determine if there is diffuse leakage throughout the abdominal cavity and an abdominal CT obtained to look for intra-abdominal abscesses. Controlled fistula can be managed nonoperatively but the wound must be carefully inspected for evidence of necrotizing fasciitis. Uncontrolled fistulae require operative intervention and are usually treated by resection of the fistula and leaking segment of colon followed by proximal diversion with an end colostomy.

Stoma complications including stomal necrosis, obstruction, peristomal evisceration, and subcutaneous abscess occur in 3%–14% of patients. Most stomal complications require operative intervention.

Wound infections occur in up to 50% of patients with colon or rectal injuries but should not be considered a complication of the repair. Virtually all wound infections can be avoided by leaving the wound open at the time of abdominal closure. Closure of the wound during the initial operation should be reserved for patients with few associated injuries, minimal subcutaneous fat, little contamination, and who have not suffered prolonged shock.

Stab wound and missile tract infections occur frequently and must be considered in any patient with evidence of systemic sepsis. A reasonable effort should be made to remove missiles and material that have traversed the colon and lodged in the soft tissue to avoid soft tissue infection and possible necrotizing fasciitis.

MORTALITY

Early death in the multiply-injured patient with colon and rectal injuries is most often a result of exsanguination from associated injuries. The late mortality rate associated with colon injuries in contemporary studies ranges from 1%–4%, most often a result of sepsis or multiple organ failure. Death occurs more often in the patients treated with colostomy, but this may be a reflection of injury severity rather than treatment method.

CONCLUSIONS AND ALGORITHM

Despite the evolution in management of colon and rectal injuries in the recent past, the key elements to treatment have remained the same. Prompt recognition, hemorrhage control, and control of enteric spillage are the immediate management priorities followed by reconstruction or diversion. Although treatment must be individualized based on each injury, the constellation of associated injuries, and the physiologic state of the patient, it is important to have a generalized institutional approach to assess treatment outcomes.

With these considerations, we have adopted an institutional approach to colon and rectal injuries outlined in Figure 4. The critical decision-making points for colon injuries are the metabolic status of the patient, the need for segmental resection, the location of the injury, and the condition of the bowel at the time of repair. Adherence to this approach enables primary repair in 70%–90% of patients. The first consideration in rectal injuries is whether the injury is identified and repaired. Patients with suspected injuries that are not directly identified or not repaired because of anatomic location are treated with proximal diversion and presacral drainage. Rectal injuries requiring segmental resection are best treated with colostomy rather than primary anastomosis during the initial operation.

Figure 4 Algorithms for the management of (A) colon and (B) rectal injuries.