Bowel Obstruction: Symptoms, Causes & Treatment

Bowel obstruction is the mechanical or functional failure of intestinal contents to traverse the bowel lumen, accounting for 12–16% of emergency surgical admissions. It is classified as mechanical (a structural barrier impeding flow) or functional — paralytic ileus (failure of peristalsis without a physical obstruction). Both carry risk of progression to ischemia, full-thickness wall necrosis, perforation, peritonitis, and sepsis if untreated.

In the small bowel, postoperative adhesions cause approximately 70% of mechanical obstructions in developed countries, followed by external hernias (inguinal, femoral, umbilical) and malignancy. Colonic obstruction is most commonly caused by colorectal cancer (65%), followed by sigmoid volvulus and diverticular disease. In low-income settings, hernias remain the predominant cause due to limited access to elective hernia repair. Strangulation — compromise of bowel blood supply — is the most feared complication, occurring in 10–15% of cases and dramatically worsening mortality.

CT abdomen and pelvis with contrast is the gold standard investigation, identifying obstruction level, cause, and ischemic features (pneumatosis intestinalis, portal venous gas). Prompt fluid resuscitation, nasogastric decompression, electrolyte correction, and surgical consultation are the cornerstones of management.

• Colicky, cramping abdominal pain (intermittent with peristaltic waves)
• Abdominal distension — more pronounced in distal obstructions
• Nausea and vomiting (bilious in small bowel; feculent in large bowel obstruction)
• Absolute constipation — no passage of flatus or stool
• Strangulation signs: continuous severe pain, fever, tachycardia, peritoneal signs (rebound, guarding) — emergency

• Postoperative adhesions — leading cause of small bowel obstruction (~70%)
• External hernia with incarceration/strangulation (inguinal, femoral, umbilical, incisional)
• Colorectal cancer — leading cause of large bowel obstruction (65%)
• Colonic or sigmoid volvulus (especially in elderly or institutionalized patients)
• Crohn's disease with inflammatory or fibrotic strictures
• Paralytic ileus: post-abdominal surgery, hypokalemia, peritonitis, mesenteric ischemia, medications (opioids)

Clinical diagnosis is supported by erect abdominal X-ray (dilated loops, air-fluid levels, absence of gas in the rectum). CT abdomen and pelvis with oral and IV contrast is the gold standard: identifies obstruction site, cause, closed-loop obstruction, and ischemia. Blood tests: CBC (leukocytosis suggests strangulation), serum lactate (elevated in ischemia), BMP, and amylase. Rectal examination mandatory to assess rectal tone and exclude impacted fecal mass.

Initial: NPO, nasogastric decompression, aggressive IV fluid resuscitation (Hartmann's/normal saline), electrolyte correction, urinary catheter for output monitoring, analgesia. Partial small bowel obstruction from adhesions: non-operative management with close monitoring succeeds in 70–80% within 48–72 hours; water-soluble contrast challenge (Gastrografin) both diagnostic and therapeutic. Complete obstruction or strangulation: emergency laparotomy — adhesiolysis, manual reduction and hernia repair, resection of ischemic bowel with primary anastomosis or stoma formation. Colorectal cancer obstruction: decompressing colostomy or stenting then semi-elective resection.

• Strangulation with ischemia, necrosis, and bowel perforation
• Peritonitis and septic shock from free perforation
• Electrolyte imbalance and severe dehydration from vomiting and third-space losses
• Short bowel syndrome after extensive small intestinal resection

• Elective hernia repair before incarceration occurs
• Laparoscopic surgical technique reduces adhesion formation compared to open surgery
• Adhesion barriers (Seprafilm) in selected cases of previous multiple laparotomies
• Early treatment of colorectal cancer, Crohn's strictures, and sigmoid volvulus to prevent acute obstruction