Intestinal obstruction is a serious surgical emergency defined as a partial or complete blockage of the small or large bowel preventing the normal passage of intestinal contents. It is broadly classified into two major categories: mechanical obstruction, where a physical barrier obstructs the bowel lumen caused most commonly by postoperative adhesions (the leading cause in adults), hernias, colorectal cancer, volvulus or intussusception and functional obstruction (paralytic ileus), where the bowel loses its peristaltic activity in the absence of a mechanical cause, typically following abdominal surgery, peritonitis or electrolyte imbalances. A further critical distinction is made between simple obstruction (blood supply intact) and strangulated obstruction (blood supply compromised), the latter representing a life-threatening emergency demanding immediate surgical intervention.
Symptoms
The clinical presentation depends on the site and degree of obstruction. The four cardinal features are colicky abdominal pain cramping in nature and coming in waves as the bowel contracts against the obstruction abdominal distension, vomiting and absolute constipation (failure to pass both faeces and flatus), which is a hallmark of complete obstruction. Small bowel obstruction tends to present with early, frequent vomiting and central abdominal pain with less marked distension, whereas large bowel obstruction produces more pronounced distension, later-onset vomiting that may become faeculent and lower abdominal pain. Signs of strangulation including constant severe pain (rather than colicky), fever, tachycardia and peritonism on examination indicate bowel ischaemia and demand urgent surgical assessment.
Diagnosis
The diagnosis is clinical and radiological. Plain erect abdominal X-ray is the first-line investigation, classically demonstrating dilated loops of bowel with multiple air-fluid levels. CT scan of the abdomen and pelvis with contrast is the gold standard investigation, providing precise identification of the level and cause of obstruction, assessment of bowel viability and detection of complications such as perforation or ischaemia. Blood tests including full blood count, urea and electrolytes, C-reactive protein and lactate are essential to assess hydration status, metabolic derangement and any evidence of bowel compromise.
Treatment
Initial management in all cases follows a structured "drip and suck" approach intravenous fluid resuscitation to correct dehydration and electrolyte imbalances and nasogastric tube decompression to relieve distension and vomiting alongside urinary catheter insertion for accurate fluid balance monitoring. For adhesional small bowel obstruction without signs of strangulation, a trial of conservative management for 24–48 hours is appropriate, as a significant proportion resolve with non-operative treatment. Surgical intervention becomes mandatory in cases of complete obstruction failing conservative management, strangulation, closed-loop obstruction, or obstruction secondary to a hernia or malignancy. The operative approach whether laparoscopic or open is tailored to the underlying cause: adhesiolysis for adhesions, bowel resection and anastomosis for ischaemic or perforated segments, hernia repair or defunctioning colostomy for obstructing colorectal cancer. Early recognition of strangulation and prompt surgical decompression are the critical determinants of outcome, as delayed intervention significantly increases the risk of bowel necrosis, perforation, sepsis and mortality.