(500) Diamonds Are Not the Bladder’s Best Friend: Sulfamethoxazole as a Cause of Bladder Obstruction

Introduction: Sulfamethoxazole-trimethoprim therapy is known to cause crystalluria leading to acute kidney injury. The incidence of crystalluria from sulfamethoxazole-trimethoprim is up to 50% in some reports, with dehydration as a known risk factor. There are no case reports, to our knowledge, that discuss crystalluria leading to complete bladder obstruction.

Description: An elderly male was admitted with ARDS requiring intubation secondary to Pneumocystis and Nocardia pneumonia. The pneumonia was treated with a combination of high-dose sulfamethoxazole-trimethoprim, imipenem-cilastatin, and amikacin therapy as directed by infectious disease physicians. On day 10 of therapy the patient’s urine output dropped to zero despite no change in renal function based on laboratory values. Amikacin was held until the cause of abrupt urine output change could be elucidated. An ultrasound was used to visualize the bladder which revealed sand-like sediment obstructing urine output, for which a three-way foley was placed and continuous bladder irrigation was initiated. Once bladder irrigation was started, the patient’s urine output returned to normal. The resultant urine was examined under urine microscropy which revealed presence of sulfamethoxazole crystals. Therefore, the diagnosis of sulfamethoxazole-induced crystalluria leading to bladder obstruction was made. Continuous bladder irrigation was paused after urine output resumed for several days during continued treatment with sulfamethoxazole-trimethoprim. However, the obstruction returned and therefore continuous bladder irrigation was restarted. The patient ultimately succumbed to their illness before further interventions were employed.

Discussion: Our patient experienced crystalluria that lead to complete bladder obstruction, responsive to continuous bladder irrigation. It is important for clinicians to be aware of bladder obstruction as a manifestation of sulfamethoxazole crystalluria and the ease of use with bedside ultrasound to assess and address the problem.