Anatomy clinical correlates Quiz: Ace Your Exams

A 34-year-old woman comes to the office to be evaluated for recurrent episodes of epigastric bloating and crampy pain. The pain usually begins after eating and is relieved by vomiting or lying on her stomach. The patient is a dancer and joined a training program a few months ago. She has lost 30-lbs (13.6 kg) over the past two months while on a “crash diet.” Past medical history is noncontributory. Temperature is 36.7°C (98°F), pulse is 100/min, respirations are 18/min, and blood pressure is 135/75 mmHg. Physical examination shows a mildly distended and tender abdomen with high-pitched bowel sounds. A plain abdominal x-ray reveals findings suggestive of proximal small bowel obstruction. The upper gastrointestinal series demonstrates a marked delay in the passage of the contrast from the duodenum into the more distal small bowel. The delay resolves when the patient takes a knee-chest position. Which of the following is the most likely cause of this patient’s condition?