A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 32-year-old Caucasian female is admitted to the emergency department with a 48-hour history of severe and diffuse abdominal pain, nausea, vomiting, and constipation. Her personal history is unremarkable except for an ectopic pregnancy 5 years ago. Upon admission, she is found to have a blood pressure of 120/60 mm Hg, a pulse of 105/min, a respiratory rate 20/min, and a body temperature of 37°C (98.6°F). She has diffuse abdominal tenderness, hypoactive bowel sounds, and mild distention on examination of her abdomen. Rectal and pelvic examination findings are normal. An abdominal plain film of the patient is given. What is the most likely cause of this patient’s condition?
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A
HerniaIncorrect. Hernias are the second most common cause of SBO and the most common cause in patients without prior surgery; she has prior surgery.
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B
AdhesionsCorrect. Postoperative adhesions (from her prior ectopic-pregnancy surgery) are the most common cause of small-bowel obstruction in the developed world.
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C
Enlarged Peyer’s plaquesIncorrect. Enlarged Peyer's patches cause intussusception in children (often after a viral illness), not SBO in an adult with prior pelvic surgery.
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D
Gastrointestinal malignancyIncorrect. GI malignancy can cause SBO but more often produces large-bowel obstruction; it is less common than adhesions in a patient with prior surgery.
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E
VolvulusIncorrect. Volvulus (sigmoid or cecal) causes large-bowel obstruction in elderly or institutionalized patients with chronic constipation, not small-bowel obstruction in a 32-year-old with prior pelvic surgery.
↑ Tap an answer to reveal the reasoning
Answer: B. A woman with prior abdominal/pelvic surgery (ectopic pregnancy 5 years ago) presents with the classic tetrad of small-bowel obstruction: colicky abdominal pain, vomiting, constipation/obstipation, and distention. Hypoactive bowel sounds and diffuse tenderness reinforce the diagnosis. In the developed world, the single most common cause of small-bowel obstruction — accounting for ~60–70% of cases — is postoperative adhesions.
Adhesions form as fibrous bands between bowel and abdominal wall or between loops of bowel after peritoneal injury (surgery, infection, inflammation). They can cause obstruction years to decades after the inciting event. Treatment of partial SBO is bowel rest, NG decompression, and IV fluids; complete obstruction, signs of strangulation (peritonitis, fever, leukocytosis, lactic acidosis), or failure to resolve in 48–72 hours mandates surgery.
Hernias are the second most common cause overall and the most common cause in patients without prior surgery. Malignancy and intussusception are less common adult causes.
**Why each option:**
**A.** Hernias are the second most common cause of SBO and the most common cause in patients without prior surgery; she has prior surgery.
**B.** Correct. Postoperative adhesions (from her prior ectopic-pregnancy surgery) are the most common cause of small-bowel obstruction in the developed world.
**C.** Enlarged Peyer's patches cause intussusception in children (often after a viral illness), not SBO in an adult with prior pelvic surgery.
**D.** GI malignancy can cause SBO but more often produces large-bowel obstruction; it is less common than adhesions in a patient with prior surgery.