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[firstaid2012]

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38. A 65-year-old woman with chronic constipation comes to the emergency department because of a 3-day history of abdominal pain. Abdominal examination shows distention with tendemess in the Ieft lower quadrant.
Sigmoidoscopy shows no tumors, but the scope cannot be inserted beyond 15 cm because of abrupt Iuminal
narrowing. Which of the following is the most likely diagnosis?
0 A) Appendicitis
O B) Diverticulosis
OC) Small-bowel obstruction
O D) Volvulus of the cecum
0 E) Volvulus of the sigmoid colon

please explain

 

[ashik33]

I think the correct answer here is E. Volvulus of the sigmoid colon

Reasons:
- Sigmoid colon is the most common site for volvulus in the large intestine (followed by cecum)
- Volvulus is more common in elderly patients
- Since the scope can't be passed beyond 15 cm mark, it indicates that the obstruction should be at the level of sigmoid colon. During volvulus, the bowel segment twists along the axis of the mesentary leading to compression at 2 sites with dilated portion of bowel in between (this is sometimes referred to as closed loop obstruction)
- Constipation and abdominal distension are signs of intestinal obstruction. Pain has acute pain and tenderness. This may be due to ischemic infarction of the bowel wall due to obstruction of the vessels at the site of twisting

[Another possible explanation (may not hold true): Since the patient is having chronic constipation, her sigmoid colon (normal reservoir of feces) may be loaded with large amount of hard feces. This increases the weight of the sigmoid colon and hence increases the torque (Torque = Force * Moment Arm). Thus the bowel segment has increased tendency to undergo axial rotation)