We report an unusual case of spontaneous subcapsular and perinephric hematoma in a 67-year-old woman with solitary functioning kidney and long-standing chronic kidney disease due to obstructive uropathy. Her medical history included history of obesity, hypertension, hepatitis C and history of opioid abuse. Her surgical history was notable for laparoscopic gastric bypass surgery.
Her renal function was normal prior to 6/2012 when she had symptomatic right sided obstructing kidney stone with hydronephrosis. This was associated with acute kidney injury (creatinine peaked at 1.5 mg/dl) and required lithotripsy and ureteric stent placement. She had another episode of acute kidney injury 15 months later which was determined to be due to acute tubular necrosis (ATN) in the setting of a urinary tract infection and volume depletion and her creatinine peaked at 10.4 mg/dl. She did not require renal replacement therapy and although her renal function improved, she had residual stage 4 chronic kidney disease (CKD) with creatinine around 2-2.6 mg/dl (estimated GFR 22 ml/min). She was also incidentally found to have a right sided solid renal mass in 7/2013 on an MRI and was followed with serial imaging. This was suspected to be papillary renal cancer based on imaging and it remained stable on subsequent imaging studies.
In 1/2016, approximately 4 years after the initial episode of right sided hydronephrosis, she suffered from another episode of acute left sided flank pain. CT scan showed left sided obstructing stone in the ureter with associated hydronephrosis and atrophic kidney on the right side which measured around 8 centimeters. In the setting of obstruction of her presumably only functioning kidney, she developed severe AKI and her creatinine peaked at 13.2 mg/dl. She required percutaneous nephrostomy tube placement on the left side followed by lithotripsy and ureteric stent placement. Following the resolution of hydronephrosis, her renal function improved and it remained stable over the next 4 years with creatinine between 2-2.6 mg/dl.
In 11/2020, she presented with sudden onset of left sided flank pain which was similar to her previous episodes of nephrolithiasis. She did not have hematuria or symptoms to suggest urinary tract infection. On examination, she was not in distress and vital signs on presentation to the emergency department were: temperature 98.1oF, heart rate 82 beat per minute, blood pressure 92/51mmHg, respiratory rate 16 per min and oxygen saturation 98% on room air. She was noted to have conjunctival pallor and left renal costovertebral angle tenderness. Evaluation (Table 1) was notable for acute anemia with hemoglobin of 6.3 g/dl down from 10.2g/dl and acute renal injury with creatinine up to 5.3 mg/dl. Urinalysis showed 2-10 RBCs and urine protein to creatinine ratio was 0.4 g/g.
CT of abdomen and pelvis without contrast showed left sided sub-capsular hematoma and surrounding peri-renal hematoma and contralateral atrophic kidney on the right side (Figure. 1). Renal ultrasound showed a complex collection on the left suggestive of peri-renal hematoma. Prior to this presentation, she had not sustained any trauma, undergone urological interventions, or kidney biopsy and she had not been taking any antiplatelet, non-steroidal analgesics or anticoagulants.
She was managed conservatively and received three units of packed red blood cell transfusion to keep hemoglobin above 7g/dl. She developed hyperkalemia (potassium 6.3 meq/L) and acidemia due to metabolic acidosis (venous PH 7.22 with bicarbonate of 15). She was given isotonic sodium bicarbonate (150 meq of sodium bicarbonate in 1 L of D5W) along with intravenous furosemide with improvement in acidemia and hyperkalemia. She did not need renal replacement therapy and her renal function improved but did not recover back to her previous level of functioning. At 8 months after discharge, her creatinine was 3.7 mg/dl (eGFR 13 ml/min) and ultrasound of her kidneys showed near complete resolution of the hematoma. (Figure 2)