Acute pyelonephritis complicated by subcapsular and perinephric hematoma: Diagnostic role of CT scan and 6-month follow-up

Acute pyelonephritis is a common renal infection that can become life-threatening when complicated by structural abnormalities, resistant pathogens, or systemic comorbidities such as diabetes mellitus. While common complications include renal abscess and sepsis, spontaneous subcapsular hematoma is a rare but serious manifestation that requires prompt recognition and intervention. This article reports the case of a 54-year-old female with a history of diabetes mellitus, hypertension, and hyperlipidemia, who presented with fever, flank pain, vomiting, and gross hematuria. She was diagnosed with complicated pyelonephritis and sepsis. Laboratory workup revealed leukocytosis, anemia, and thrombocytopenia. Coagulation studies were within normal limits, and the patient was not on any anticoagulant therapy. Initial abdominal CT showed left renal parenchymal inflammation without fluid collection. Follow-up imaging revealed a subcapsular hematoma compressing the left kidney, with associated extension into the left psoas muscle. The patient received broad-spectrum antibiotics, ICU-level care, and multiple transfusions. Over the course of hospitalization and follow-up, she required percutaneous drainage and was eventually scheduled for nephrectomy due to significantly reduced left renal function. This case documents the radiologic changes of subcapsular, perinephric, and psoas hematomas over 2- and 6-month intervals, allowing detailed evaluation of their progression through serial imaging follow-up.