Most obstructions in the large bowel occur in the sigmoid colon. The most common causes are carcinoma, diverticulitis, inflammatory bowel disorders, and fecal impaction. Adenocarcinoid tumors account for the majority of large bowel obstructions (Hopkins, 2016). Most tumors occur distal to the splenic flexure, making them accessible with a flexible sigmoidoscope.

Intestinal obstruction (mechanical or functional) occurs when blockage prevents the flow of contents through the intestinal tract. Large bowel obstruction results in an accumulation of intestinal contents, fluid, and gas proximal to the obstruction. Obstruction in the colon can lead to severe distention and perforation unless gas and fluid can flow back through the ileal valve. Dehydration occurs more slowly than in small bowel obstruction. If the blood supply is cut off, intestinal strangulation and necrosis occur; this condition is life-threatening. Adenocarcinoid tumors account for the majority of large bowel obstructions.

Symptoms develop and progress relatively slowly.

• Constipation may be the only symptom for months (obstruction in sigmoid colon or rectum).
• Blood loss may occur in the stool, which may result in iron deficiency anemia.
• The patient may experience weakness, weight loss, and anorexia.
• The abdomen eventually becomes markedly distended, loops of large bowel become visibly outlined through the abdominal wall, and the patient has crampy lower abdominal pain.
• Fecal vomiting develops; symptoms of shock may occur.

Diagnosis is made based on symptoms plus imaging studies (abdominal x-ray and abdominal CT scan or MRI; barium studies are contraindicated). Occasionally, flexible sigmoidoscopy is used to confirm the diagnosis.

• Restoration of intravascular volume, correction of electrolyte abnormalities, and nasogastric aspiration and decompression are instituted immediately.
• Colonoscopy is performed to untwist and decompress the bowel, if obstruction is high in the colon.
• Cecostomy may be performed for patients who are poor surgical risks and who urgently need relief from the obstruction.
• Rectal tube is used to decompress an area that is lower in the bowel.
• Endoscopically placed stents may be used as a palliative intervention or bridge to definitive surgery.
• Usual treatment is surgical resection to remove the obstructing lesion; a temporary or permanent colostomy may be necessary; an ileoanal anastomosis may be performed if entire large bowel must be removed.

• Monitor symptoms indicating worsening intestinal obstruction.
• Provide emotional support and comfort.
• Administer IV fluids and electrolyte replacement.
• Prepare patient for surgery if no response to medical treatment.
• Provide preoperative education as patient's condition indicates.
• After surgery, provide general abdominal wound care and routine postoperative nursing care.

For more information, see Chapter 47 in Hinkle, J. L., & Cheever, K. H. (2018). Brunner and Suddarth's textbook of medical-surgical nursing (14th ed.). Philadelphia, PA: Lippincott Williams & Wilkins.