A 65-year-old man comes to the office with 2 weeks of dysuria and turbid, foul-smelling urine. He has also noticed air bubbles while urinating. He has no fever, hematuria, hematochezia, weight loss, or pelvic or flank pain. The patient has a long history of straining on urination and a weak urine stream and is currently being treated for benign prostatic hyperplasia. Four weeks ago, he was seen in the emergency department for persistent lower quadrant abdominal pain and diagnosed with acute diverticulitis. He was discharged on an oral antibiotic. Current temperature is 98.7 F (37.1 C), blood pressure is 132/84 mm Hg, and pulse is 72/min. The abdomen is soft and mildly tender in the left lower quadrant. There is no costovertebral angle tenderness. Rectal examination shows a smooth, enlarged, nontender prostate. Laboratory studies show normal complete blood count and serum chemistries, including serum creatinine. Urinalysis is positive for numerous white cells and bacteria. Urine culture grows Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae. Which of the following is the most likely cause of this patient's current condition?

Question

A 65-year-old man comes to the office with 2 weeks of dysuria and turbid, foul-smelling urine.  He has also noticed air bubbles while urinating.  He has no fever, hematuria, hematochezia, weight loss, or pelvic or flank pain.  The patient has a long history of straining on urination and a weak urine stream and is currently being treated for benign prostatic hyperplasia.  Four weeks ago, he was seen in the emergency department for persistent lower quadrant abdominal pain and diagnosed with acute diverticulitis.  He was discharged on an oral antibiotic.  Current temperature is 98.7 F (37.1 C), blood pressure is 132/84 mm Hg, and pulse is 72/min.  The abdomen is soft and mildly tender in the left lower quadrant.  There is no costovertebral angle tenderness.  Rectal examination shows a smooth, enlarged, nontender prostate.  Laboratory studies show normal complete blood count and serum chemistries, including serum creatinine.  Urinalysis is positive for numerous white cells and bacteria.  Urine culture grows Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae.  Which of the following is the most likely cause of this patient's current condition?

Quizplus · Accepted Answer

11ec25c8_d8eb_78e6_bc81_e53ae20d8704_MD0003_00 This patient's presentation is consistent with colovesical fistula (connection between the colon and bladder), which can be a complication of acute diverticulitis. The mechanism is usually due to direct extension of a ruptured diverticulum or erosion of a diverticular abscess into the bladder. Patients typically develop fecaluria (stool in the urine) or pneumaturia (air in the urine) that usually occurs at the end of urination as the gas collects at the top of the bladder. Patients can also develop recurrent urinary tract infections (sometimes due to mixed flora with coliform organisms) or other nonspecific symptoms that can sometimes delay the diagnosis. Colovesical fistula can also occur in patients with Crohn disease or malignancy (usually of the colon). Abdominal CT scan with oral or rectal (not intravenous) contrast can confirm the diagnosis by showing contrast material in the bladder with thickened colonic and vesicular walls. Colonoscopy is usually recommended in patients diagnosed with colovesical fistula to exclude colonic malignancy. Treatment is typically surgical after resolution of the infection. (Choices A and E) Acute bacterial prostatitis typically presents with acute onset of systemic findings (eg, fever, chills, malaise), irritative urinary symptoms (eg, dysuria, frequency), pelvic/perineal pain, and cloudy urine. Prostatic abscess, a focal purulent collection, is a complication of acute bacterial prostatitis. However, both conditions usually cause an exquisitely tender prostate on rectal examination and are not usually associated with pneumaturia. (Choice B) Bladder cancer classically presents with irritative urinary symptoms and painless hematuria. This patient's pneumaturia and absence of hematuria make this less likely. (Choice D) Emphysematous pyelonephritis (pyelonephritis due to a gas-producing infection, typically in patients with diabetes) can present with abrupt or gradual onset of fever, chills, flank or abdominal pain, and nausea/vomiting. This patient's absence of fever and flank pain makes this less likely. Emphysematous pyelonephritis (Choice F) Staghorn calculi, which are typically due to struvite stones filling the entire intrarenal collecting system, can lead to recurrent urinary tract infections. Patients can develop irritative urinary symptoms, flank pain, or hematuria. However, staghorn calculi are not usually associated with pneumaturia. Staghorn calculi Educational objective: Colovesical fistula is most commonly due to diverticular disease and presents with pneumaturia, fecaluria, or findings consistent with urinary tract infection. Abdominal CT scan with oral or rectal (not intravenous) contrast can confirm the diagnosis by showing contrast material in the bladder with thickened colonic and vesicular walls. References: A case of colovesical fistula induced by sigmoid diverticulitis. (http://www.ncbi.nlm.nih.gov/pubmed/21602969)

A 65-Year-Old Man Comes to the Office with 2 Weeks