Gastroenterology · Acute Abdomen
The facts most likely to be tested
Post-surgical adhesions are the most common cause of small bowel obstruction in patients with a history of prior abdominal surgery.
Classic clinical presentation includes colicky abdominal pain, nausea, vomiting, and obstipation (failure to pass flatus or stool).
Physical examination typically reveals hyperactive, high-pitched bowel sounds early in the course, which may progress to silent abdomen as the bowel becomes exhausted.
Abdominal CT with IV contrast is the diagnostic modality of choice to determine the site, severity, and potential etiology of the obstruction.
Radiographic findings on an upright abdominal series include dilated loops of small bowel, air-fluid levels, and a lack of gas in the colon.
Strangulated obstruction is a surgical emergency characterized by fever, tachycardia, leukocytosis, and localized peritoneal signs.
Initial management for uncomplicated small bowel obstruction consists of bowel rest, IV fluid resuscitation, and nasogastric tube decompression.
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A 54-year-old female presents to the emergency department with a 2-day history of worsening diffuse abdominal pain, nausea, and bilious vomiting. She reports she has not passed gas or stool in 24 hours. Her surgical history is significant for an open appendectomy 10 years ago. On physical exam, the abdomen is distended and tympanitic to percussion with high-pitched, tinkling bowel sounds. Laboratory studies show a mild leukocytosis and evidence of dehydration.
What is the most appropriate initial management for this patient?
Bowel rest, IV fluid resuscitation, and nasogastric tube decompression.
This patient presents with classic signs of a small bowel obstruction secondary to adhesions; initial management for a stable patient without signs of strangulation is conservative, non-operative decompression.
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Etiology / Epidemiology
Most common cause is post-surgical adhesions. Always consider hernias in patients without prior surgery.
Clinical Manifestations
Presents with colicky abdominal pain, bilious vomiting, and obstipation. Look for high-pitched bowel sounds.
Diagnosis
CT scan with IV contrast is the gold standard. Look for transition point and dilated loops >3cm.
Treatment
Initial management is bowel rest, IV fluids, and nasogastric tube decompression. Emergent surgery for strangulation.
Prognosis
Risk of bowel necrosis increases with delay. Monitor for leukocytosis and fever as signs of ischemia.
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Epidemiology & Etiology
Post-surgical adhesions account for 60-75% of cases. In patients without surgical history, hernias (inguinal/femoral) are the primary etiology. Malignancy and Crohn's disease are secondary considerations.
Pertinent Anatomy
The small bowel is prone to obstruction due to its narrow lumen and fixed points. Obstruction leads to proximal dilation and distal collapse, creating a distinct transition point visible on imaging.
Pathophysiology
Proximal accumulation of gas and fluid causes bowel distension, stimulating hyperperistalsis initially. This manifests as tinkling bowel sounds. Prolonged distension leads to venous congestion, mucosal edema, and eventually bowel ischemia and perforation.
Clinical Manifestations
Patients report cramping abdominal pain, nausea, and vomiting. Physical exam reveals abdominal distension and tympany. Fever, tachycardia, and localized peritonitis are red flags for strangulated obstruction requiring immediate surgical intervention.
Diagnosis
CT scan of the abdomen/pelvis with IV contrast is the diagnostic test of choice. Findings include dilated small bowel loops >3cm, air-fluid levels, and a transition point. Plain films may show stack of coins or string of pearls sign.
Treatment
Stable patients receive IV fluid resuscitation, electrolyte correction, and nasogastric tube decompression. Do not delay surgery if signs of peritonitis or ischemia are present. If no improvement after 24-48 hours of conservative management, surgical exploration is indicated.
Prognosis
The primary concern is bowel necrosis and perforation. Patients must be monitored for leukocytosis and metabolic acidosis, which suggest impending gangrene.
Differential Diagnosis
Ileus: absent bowel sounds, diffuse dilation
Volvulus: cecal or sigmoid twisting, coffee bean sign
Mesenteric Ischemia: pain out of proportion to exam
Appendicitis: localized RLQ pain, fever
Gastroenteritis: diarrhea is the predominant symptom