Fecal impaction Quiz: Ace Your Exams

A 91-year-old woman presents to the emergency department with progressive abdominal distention and lack of bowel movements for more than a week. She is nonverbal but accompanied by her adult son who provides additional history. He states that she has a past medical history of hypothyroidism, hypertension, osteoarthritis, constipation, and a recent stroke. She is no longer able to ambulate and spends much of her time in bed. Temperature is 37.6°C (99.7°F), blood pressure is 142/81, pulse is 92/min, respiratory rate is 17/min, and oxygen saturation is 94% on room air. On physical examination, she appears mildly uncomfortable, her lower abdomen is moderately distended, and there is a palpable left lower quadrant mass. A hard mass of stool is palpated in the rectum. An X-ray of the abdomen and pelvis is performed and is shown below. Which of the following is the most likely diagnosis?
 
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