Unilateral Ureteral Obstruction Due to Retained Blood Clot as a Complication of Percutaneous Kidney Biopsy

Introduction: Urinary tract obstruction due to retained clot in the urinary system after percutaneous renal biopsy (PRB), is a rare complication that can lead to acute kidney injury (AKI) and if not promptly diagnosed and managed, can lead to irreversible kidney damage. Case Description: We report the case of a 63-year-old man known to have IgA nephropathy with chronic kidney disease (CKD) stage 3B, who underwent PRB of the left kidney for progressive unexplained decline in renal function. After the procedure, he developed gross hematuria with passage of blood clots. This culminated in several hours of anuria, relieved after the passage of a large clot. Despite this, worsening flank pain prompted an emergency department visit. While his vital signs were stable, he was diagnosed with acute on chronic kidney injury and was admitted to the hospital . A CT scan without contrast done on presentation, showed no evidence of perinephric hematoma or hydronephrosis. In the following 24 hours, serum creatinine continued to rise despite administration of isotonic saline. A CT angiogram of the abdomen and pelvis done on hospital day 2 revealed mild left hydronephrosis. After an urgent consultation with urology, a cystourethroscopy revealed retained clot in the left ureter and an ureteral stent was placed with improvement in patient’s flank pain and renal function. Discussion: Ureteral obstruction due to retained clot after renal biopsy is a rare but important complication with important implications for kidney health. The diagnosis relies on a high index of suspicion and early intervention is important in effectively managing this condition. Importantly, in the acute phase, imaging may fail to show hydronephrosis as the renal pelvis takes time to dilate in the early obstructive phase. AKI, lack of hypotension or shock, persistent flank pain in the absence of imaging evidence of hematoma and history of gross hematuria with clot passage, are important clinical clues that inform the diagnostic and management approach in this condition. Urgent urological consultation and restoration of renal pelvis drainage is essential to prevent long lasting renal damage to the affected kidney.