Leveraging Natural Language Processing to Evaluate the Evolution of Subcapsular Renal Hematomas: Report of a 10-Year Retrospective Multi-Institution Study

Abstract

Purpose:

To characterize the etiology and clinical course of patients with subcapsular renal hematoma (SRH) in order to better understand and manage patients in the acute and chronic settings.

Materials and Methods:

A natural language processing algorithm screened computed tomography and magnetic resonance imaging studies for “subcapsular renal hematoma” across 10 inpatient facilities from 2011 to 2021. Patients with at least three cross-sectional exams were included. Retrospective chart review assessed etiology, clinical course, and management of SRH.

Results:

A total of 105 patients with acute SRH were included. The underlying etiologies involved traumatic (21%), spontaneous (32%), and iatrogenic causes (47%). Three patients developed Page kidney with hypertension secondary to renin-angiotensin-aldosterone system activation. Notably, two of these patients had solitary kidneys, with one necessitating temporary hemodialysis and the other undergoing hematoma evacuation. Additionally, six patients developed infected hematomas; five required drainage by interventional radiology (IR), and one patient underwent nephrectomy. Angiography by IR was recommended in 21 patients, 17 of whom underwent renal artery embolization. One patient developed intractable pain, requiring operative hematoma evacuation. Another patient developed abdominal compartment syndrome requiring decompressive laparotomy. Repeat imaging was done within 1–10 months in 69 patients, with 11 (16%) demonstrating complete hematoma resolution. In 16 patients who had further imaging between 10 and 15 months, an additional 8 had resolved. The average time to complete resolution was 368 days.

Conclusion:

Subcapsular hematoma is a rare finding, most commonly occurring after iatrogenic causes. In our series, roughly 1/3 (34%) of all hematomas require intervention, including hemodialysis, embolization, and nephrectomy. One third (33%) of spontaneous SRH required embolization, most commonly those with underlying renal masses. Three patients developed the Page kidney phenomenon, which was more common in patients with a solitary kidney.