WBR0931

Author	PageAuthor::William J Gibson (Reviewed by Serge Korjian)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Gastrointestinal
Prompt	[[Prompt::A 26-year-old woman is admitted to the emergency department for severe right lower quadrant pain. Following appropriate work-up, she is diagnosed with acute appendicitis and undergoes emergency appendectomy. Her postoperative course is complicated by persistent, diffuse abdominal pain, with palpable distension. She is unable to tolerate an oral diet due to nausea and vomiting after any food ingestion. Despite feeling bloated she has not passed any flatus 5 days after the operation. Upright abdominal X-rays are negative for signs of bowel obstruction. Which of the following pharmacotherapies may help treat this patient’s condition?]]
Answer A	AnswerA::Bethanechol
Answer A Explanation	AnswerAExp::Bethanechol is a cholinomimetic agent that can be used to treat postoperative ileus and urinary retention.
Answer B	AnswerB::Erythromycin
Answer B Explanation	AnswerBExp::While erythromycin can increase intestinal motility, it is ineffective in the setting of postoperative ileus.
Answer C	AnswerC::Neostigmine
Answer C Explanation	AnswerCExp::Neostigmine is a cholinesterase inhibitor that can be used to reverse neuromuscular junction blockade and treat myasthenia gravis. It is ineffective for the treatment of postoperative ileus.
Answer D	AnswerD::Carbachol
Answer D Explanation	AnswerDExp::Carbachol is a cholinomimetic drug (CARBon copy of acetylcholine). Carbachol eyedrops are used to decrease the pressure in the eye for people with glaucoma. It is sometimes used to constrict the pupils during cataract surgery.
Answer E	AnswerE::Methacholine
Answer E Explanation	AnswerEExp::Methacholine is an inhaled non-selective muscarinic receptor agonist used in “challenge tests” to diagnose bronchial hyperreactivity (asthma and COPD).
Right Answer	RightAnswer::A
Explanation	[[Explanation::Postoperative ileus should be suspected when a patient has nausea/vomiting, abdominal distension and failure to pass flatus for at least 3-5 days following abdominal surgery. Before making the diagnosis of postoperative ileus, bowel obstruction must be ruled out. Postoperative ileus is thought to occur due to inflammation caused by surgical manipulation of the bowel. The muscarinic receptors in the bladder and gastrointestinal tract stimulate contraction of the bladder and expulsion of urine, and increased gastrointestinal motility, respectively. Bethanechol is a cholinomimetic agent that can be used to treat postoperative ileus and urinary retention. It should be used to treat these disorders only after mechanical obstruction is ruled out as a possible cause. Educational Objective: Bethanechol is a cholinomimetic agent that can be used to treat postoperative ileus and urinary retention. References: Smith AJ, Nissan A, Lanouette NM, Shi W, Guillem JG, Wong WD, Thaler H, Cohen AM. Prokinetic effect of erythromycin after colorectal surgery: randomized, placebo-controlled, double-blind study. Dis Colon Rectum. 2000;43(3):333. Myrhöj T, Olsen O, Wengel B. Neostigmine in postoperative intestinal paralysis. A double-blind, clinical, controlled trial. Dis Colon Rectum. 1988;31(5):378. First Aid 2013 page 233]]
Approved	Approved::Yes
Keyword	WBRKeyword::Bethanechol, WBRKeyword::Postoperative, WBRKeyword::Postoperative ileus, WBRKeyword::IIeus, WBRKeyword::Gastroparesis, WBRKeyword::Gastric motility
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