COLON AND RECTAL INJURIES

Published on 20/03/2015 by admin

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CHAPTER 54 COLON AND RECTAL INJURIES

Surgical management of colon and rectal injuries has evolved dramatically since World War II. Accepted treatment at that time generally consisted of resection and end colostomy based on experience with battlefield casualties. Although a difference between civilian and military injuries was recognized, the treatment by civilian trauma surgeons paralleled that of their military counterparts. In the ensuing decades following the Korean and Vietnam wars, primary repair began to replace the “colostomy only” approach in the nonmilitary setting. Numerous prospective randomized trials in civilian centers have since established primary repair as the preferred treatment for most colon and rectal injuries.

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

  Grade Injury Description
I Hematoma Contusion or hematoma without devascularization
  Laceration Partial thickness, no perforation
II Laceration Laceration <50% of circumference
III Laceration Laceration >50% of circumference
IV Laceration Transection of colon
V Laceration Transection with segmental tissue loss

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

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  Grade Injury Description
I Hematoma Contusion or hematoma without devascularization
  Laceration Partial thickness, no perforation
II Laceration Laceration <50% of circumference
III Laceration Laceration >50% of circumference
IV Laceration Full-thickness laceration with extension into perineum
V Vascular