Evidence-based, cost-effective management of large bowel obstruction: An algorithm of the Journal of Trauma and Acute Care Surgery Emergency General Surgery Algorithms Work Group.

The initial evaluation of a patient with abdominal pain requires a detailed history and thorough physical examination. Patients with LBO usually present with infraumbilical crampy abdominal pain, distension, and obstipation. Compared with those with small bowel obstruction, LBO patients are less likely to have nausea and vomiting, unless presenting late in their course or having an incompetent/absent ileocecal valve. 10 , 11 Understanding the timing of symptom onset can help distinguish the causes of LBO. A rapid onset is more common in patients with volvulus, whereas a gradual onset may indicate a malignant or stricturing lesion. Past episodes of left lower quadrant pain suggest diverticular disease, while a history of dark/tarry stools or change in stool caliber, weight loss, and fatigue may indicate malignancy. 12 Abdominal examination may find tenderness, abdominal distension, and hyperactive or absent bowel sounds. Digital rectal examination is indicated and can be diagnostic if an intrinsic lesion is found, suggestive of rectal cancer. 13 If there are vital sign abnormalities (i.e., fever, tachycardia, hypotension) along with peritonitis, perforation should be suspected, and immediate surgical intervention is warranted. Laboratory tests results such as leukocytosis and lactic acidosis might be suggestive of ischemia. 14 Imaging is required for definitive diagnosis. Abdominal plain x-ray is often the first step when there is clinical suspicion of bowel obstruction and has been shown to have a sensitivity and specificity of 84% and 72%, respectively. 3 It is also useful in identifying volvulus. Water-soluble contrast enemas offer high sensitivity and specificity (96% and 98%) while also identifying the level of obstruction. 15 However, these studies can be difficult to obtain, are uncomfortable for patients, and cannot distinguish the causes of the obstruction. 15 , 16 Computed tomography with intravenous contrast is the test of choice. In addition to its higher diagnostic accuracy, it provides information about the etiology and location of the LBO. Computed tomography findings such as wall thickening and hyperenhancement may indicate inflammatory bowel diseases or diverticulitis, while intraluminal masses would indicate malignancy. 17 Colon dilatation is defined by a diameter greater than 9 cm in the cecum and 6 cm in the left colon. A diameter greater than 12 cm of the cecum is associated with an increased risk of perforation and suggests the need for early surgical intervention. 18 , 19 Although direct visualization of the site of obstruction occurs with colonoscopy, its role in the initial phases of diagnosis of LBO is limited, mostly because of the lack of availability in the emergency department and concern about air insufflation in an obstructed colon. Once the diagnosis of LBO has been made, the specific etiology will guide management. All patients require intravenous fluid resuscitation and repletion of electrolytes. Antibiotics should be initiated in patients with suspicion of sepsis, ischemia, or perforation. Gastric decompression should be performed in patients with significant nausea and vomiting or evidence of gastric or small bowel distension on imaging. The urgency required to treat an LBO is based on two major factors, including ( a ) the degree of obstruction, either partial or complete, and ( b ) whether the ileocecal valve is competent or not. An incompetent ileocecal valve (present in 25–40% of patients) 12 and partial LBO will both result in some decompression of the LBO into the small bowel and avoid a “closed-loop” obstruction, which is associated with markedly increased risk for ischemia and perforation. Surgical intervention is required if there is evidence of perforation or necrosis, or a high risk that either will develop. The surgical procedure depends on the etiology of the obstruction and the involved segment. Management according to etiology is discussed hereinafter in detail. If the bowel is perforated, resection and proximal diversion are recommended, although primary anastomosis can be considered in a stable patient. In the presence of hemodynamic instability, an approach involving source control, limited resection, and an open abdomen strategy followed by a planned second look can be used. 20 The patient with peritonitis and nonperforated ischemic bowel may undergo resection and anastomosis if stable; otherwise, diversion or a staged procedure is recommended. If no indication for immediate operation is present, then management depends on the etiology of the LBO. The most common problem is malignancy, for which management is guided by the site of obstruction and the patient's physiology. For lesions causing right colon obstruction that require an emergent operation in hemodynamically stable patients, a right hemicolectomy with primary ileocolic anastomosis is the procedure of choice. In hemodynamically unstable patients, a diverting loop ileostomy can be performed or right colon resection with abbreviated laparotomy and open abdomen approach with a second look laparotomy. For stable patients, a multidisciplinary approach including surgery, oncology, and gastroenterology should be undertaken. However, in a center without subspecialty surgical care and/or advanced endoscopy, it would be reasonable to perform a resection following oncologic principles with subsequent referral to oncology. For left-sided lesions, a Hartmann's procedure (sigmoid colectomy, closure of rectal stump with end-colostomy formation) should be the procedure of choice. In patients with hemodynamic instability, a diverting transverse loop colostomy could be considered. In patients with obstructing rectal lesions, a diverting sigmoid colostomy can be considered. For stable patients, as noted previously, a multidisciplinary approach is warranted. Again, if the center does not have subspecialty surgical care nor advanced endoscopy, then resection following oncologic principles should be considered, followed by a referral to oncology. Benign causes include diverticular stricture and volvulus (cecal or sigmoid). Chronic forms of diverticulitis can manifest as smoldering diverticulitis with the formation of a fibrostenotic stricture. 21 – 23 This can lead to partial or complete bowel obstruction, and its management requires a tailored approach based on the severity and patient stability. In most cases (70–92%), an emergent/urgent surgical intervention is not required. 24 – 27 Initial nonoperative management includes bowel rest, intravenous fluids, and antibiotics. 28 Endoscopic stenting has been described as a bridge to subsequent one-stage sigmoid resection and primary colorectal anastomosis. 28 Success rates with self-expanding metal stents to temporarily relieve the obstruction can be greater than 75%. 29 Nonoperative management fails in up to 20% of patients. 24 , 30 , 31 Resection and primary anastomosis are the procedure of choice for distal left colon LBO, 32 with Hartmann's procedure reserved for patients with multiple risk factors (renal failure, malnutrition, immunosuppression, American Society of Anesthesiologists III or IV, and obesity [body mass index >30 kg/m 2 ]) who are high risk for anastomotic leak and in the setting of fecal peritonitis, sepsis, shock, or widespread peritoneal malignancy. 33 The surgical approach for colon resection can be open, laparoscopic, or robotic dependent on the surgeon's skill and comfort. The laparoscopic approach has been associated with a reduction in operative time and morbidity in complicated diverticular disease. 34 Cecal volvulus occurs in patients with a mobile ileocecal region. It is a clockwise axial torsion around the ileocolic vascular pedicle, accounting for approximately 1% of colonic obstructions. 35 – 37 Imaging findings suggestive of volvulus include displacement of the cecum from the right lower quadrant to the left upper quadrant, a “coffee bean,” “bird beak,” or “whirl” sign. 36 , 38 This should be differentiated from a cecal bascule, which is an inferior to superior cecal fold. Management is surgical, as endoscopic decompression is associated with a high recurrence rate, high risk of perforation, and delay of definitive treatment. 35 , 39 , 40 A right hemicolectomy with primary anastomosis (minimally invasive or open) is the procedure of choice. 41 , 42 Resection and ileostomy are reserved for high-risk patients (those with hemodynamic instability, malnutrition, or immunosuppression) with perforation or ischemia. 35 , 36 Historically, cecopexy has also been described and may play a role in hemodynamically unstable patients. 41 , 43 Regarding the operative approach, there are no specific studies comparing a minimally invasive versus open approach; however, in a series including all types of colonic volvulus, the laparoscopic approach was associated with lower morbidity and mortality. 44 Sigmoid volvulus occurs when a freely mobile sigmoid rotates axially around the inferior mesenteric vessels between the fixed proximal and distal colon. It is more frequently seen in older male patients with chronic constipation or nonspecific motility disorders. 41 , 45 – 47 Imaging findings include an enlarged proximal and collapsed distal sigmoid (transition point) with absence of rectal gas, a “coffee bean,” “bird beak” sign, or “omega loop.” 48 , 49 Endoscopic detorsion is reserved for stable patients without evidence of perforation or ischemia. 41 , 45 , 48 Rigid or flexible sigmoidoscopy is usually sufficient, with colonoscopy required in rare cases. Decompression is successful in 65% to 90% of patients. 50 , 51 A decompression tube is usually left in place for 1 to 3 days to maintain the successful reduction. 41 , 42 Since the recurrence rates of sigmoid volvulus range from 43% to 75%, sigmoid colectomy should be strongly considered during the same admission. 40 , 45 Minimally invasive or open sigmoidectomy with primary anastomosis is the procedure of choice, depending on the surgeons comfort. In unstable patients with signs of peritonitis, ischemia, or perforation, emergent resection of the sigmoid is indicated. Detorsion should be avoided to prevent the release of endotoxins that can lead to further clinical decompensation or even inadvertent perforation. 41 , 46 Performing a primary colorectal anastomosis or a Hartmann's procedure should be based on the patient's comorbidities, hemodynamic status, and bowel viability.