A 38-year-old woman comes to the emergency department for right flank pain radiating to the groin. She also has hematuria but no dysuria or urinary frequency. She has no other medical problems and takes no medications. Her temperature is 36.7 C (98 F), blood pressure is 110/80 mm Hg, and pulse is 68/min. The patient has no costovertebral angle tenderness. Abdominal imaging shows a 6-mm calculus in the distal right ureter with no hydronephrosis. The patient's symptoms improve with intravenous hydration and analgesics. Which of the following medications will be most helpful in facilitating stone passage?

Question

A 38-year-old woman comes to the emergency department for right flank pain radiating to the groin.  She also has hematuria but no dysuria or urinary frequency.  She has no other medical problems and takes no medications.  Her temperature is 36.7 C (98 F), blood pressure is 110/80 mm Hg, and pulse is 68/min.  The patient has no costovertebral angle tenderness.  Abdominal imaging shows a 6-mm calculus in the distal right ureter with no hydronephrosis.  The patient's symptoms improve with intravenous hydration and analgesics.  Which of the following medications will be most helpful in facilitating stone passage?

Quizplus · Accepted Answer

This patient has ureteric colic secondary to a distal ureteral stone. Uncomplicated stones <1 cm can be managed conservatively with hydration, analgesics, and alpha blockers. Alpha receptors are found on the distal ureter, base of the detrusor, bladder neck, and urethra. Sympathetic activation stimulates alpha receptors to maintain high muscular tone for normal urinary continence. Reflex ureteral spasm secondary to stone impaction causes the typical waxing and waning pain seen in ureteral colic. Tamsulosin is an alpha 1 antagonist that relaxes ureteral muscle and decreases intraureteral pressure. This facilitates stone passage and reduces the need for analgesics. ureteral stone (Choices A and E) Cholinergic receptors are found on the dome of the bladder, contraction of which facilitates voiding. These receptors are not known to be present on the ureter. Bethanechol is a cholinergic agent used to treat urinary retention or atonic bladder. Oxybutynin is an anticholinergic agent that inhibits cholinergic input during bladder filling. It helps improve bladder capacity and is used to treat overactive bladder (detrusor instability). (Choice B) Finasteride is a 5-alpha-reductase inhibitor that blocks the conversion of testosterone to dihydrotestosterone. It is used as a second-line agent in the management of benign prostatic hyperplasia. (Choice C) Furosemide is a loop diuretic that promotes calciuria, which can predispose to renal calculi. (Choice D) Imipramine is an antidepressant used to treat childhood enuresis. It has anticholinergic effects and promotes urinary retention. (Choice F) Phenazopyridine is an analgesic for urinary tract mucosa frequently used to treat the dysuria of cystitis (eg, after infection or instrumentation). It may worsen stone formation (mechanism unknown). Educational objective: Alpha-1 receptor blockers such as tamsulosin act on the distal ureter, lowering muscle tone and reducing reflex ureteral spasm secondary to stone impaction. These agents facilitate stone passage and reduce the need for analgesics. References: Tamsulosin for treatment of unilateral distal ureterolithiasis: a systematic review and meta-analysis. (http://www.ncbi.nlm.nih.gov/pubmed/24852587)

A 38-Year-Old Woman Comes to the Emergency Department for Right