Acute Pyelonephritis Complicated With Spontaneous Subcapsular Renal Hematoma: A Case Report

Spontaneous subcapsular renal hematoma is a rare condition defined as spontaneous hemorrhage confined to the subcapsular and/or perirenal space. Its etiology can vary, ranging from renal tumors to vascular diseases, renal cysts, or infections. Here, we report the case of a 54-year-old male who presented to the emergency department with a two-day history of abdominal pain and fever. He was hemodynamically stable, with no abnormalities on physical examination except for mild pain on deep palpation of the left upper quadrant. Laboratory tests showed leukocytosis (24,200/μL), creatinine 1 mg/dL, C-reactive protein 20.77 mg/dL, and lactate 0.6 mmol/L. Urinalysis revealed leukocytes 10-25/HPF. An abdominal CT showed a hypodense area on the left kidney, suggesting focal pyelonephritis. He was admitted for acute pyelonephritis (APN), and empirical antibiotic therapy with ceftriaxone 2 g once daily was started. During hospitalization, Klebsiella pneumoniae was isolated from both blood and urine cultures, and antibiotic therapy was switched to cefotaxime according to susceptibility testing. Despite undergoing targeted antibiotic therapy, the patient maintained a fever, so another abdominal CT was performed, showing an external subcapsular collection of 9.1 cm × 7.9 cm × 2.8 cm, consistent with a subcapsular hematoma. Despite a drop in hemoglobin from 14 to 10 g/dL, the patient remained hemodynamically stable, so it was decided to continue conservative medical management. Spontaneous subcapsular renal hematoma, though rare in acute pyelonephritis, should be considered if symptoms persist despite antibiotics. Treatment may range from conservative monitoring to surgical intervention, depending on stability and the underlying cause.