Fat-fluid levels in renal caliceal cavities: a CT sign of lipolysis due to urine extravasation after kidney rupture

The combined uro-radiological "Rendezvous" procedure, and an unusual CT and cystoscopic finding

The ureteric "rendezvous" procedure is an interventional procedure involving both uro-radiological and cystoscopic techniques to manage complex ureteric stenoses or fistulae. We present a case in which this procedure was utilised, with an unusual intra-procedural finding. Macroscopic visualisation of lipids within the urinary tract is an unusual finding at CT, and rarely seen at cystoscopy. The aetiology of lipiduria is varied; it may indicate the presence of unrecognised pathology, occur as a sequelae of trauma, or arise secondary to intervention. Understanding the patient's history is vital to determining the likely aetiology and significance of such a finding.

CT detection of fat retention in the bladder after partial nephrectomy

PURPOSE

This study aimed to investigate the frequency of fat retention in the bladder using postoperative computed tomography (CT) and the associated imaging or clinical findings in patients who underwent renal tumor surgery.

METHODS

We retrospectively reviewed postoperative CT images from 123 patients who underwent surgery for renal tumors (92 patients after partial nephrectomy and 31 after total nephrectomy). Furthermore, we evaluated preoperative tumor characteristics per an established standardized nephrometry scoring system (the R.E.N.A.L Nephrometry Score) for patients with partial nephrectomy. We also investigated whether collecting system repair occurred during surgery.

RESULTS

Fat retention in the bladder was found in 5 patients (5.4%) after partial nephrectomy, but was not observed in any patients after total nephrectomy. No fat retention was seen immediately after partial nephrectomy (4-8 days), but occurred 2-15 months after the surgery. Subsequently, intravesical fat retention disappeared in 3 patients (8, 24, and 16 months later), and it persisted from 19-22 months after surgery in the remaining 2 patients. Collecting system repair occurred in 25 patients (27%) with partial nephrectomy. There was no statistically significant association between fat retention in the bladder and intraoperative collecting system repair (p = 0.12). The association with intravesical fat retention was not significant for either tumor size, distance to the collecting system, or the R.E.N.A.L. Nephrometry Score.

CONCLUSION

Fat retention in the bladder after partial nephrectomy can be observed using CT, although it is relatively rare. It is clinically asymptomatic and disappears spontaneously in most cases.

Lipiduria presenting following right hemicolectomy: A case presentation and brief review of the literature

Lipiduria, also known as lipuria, refers to the presence of lipids within the urine. When lipids are present in macroscopic quantities, lipiduria can be visualized as a fat-fluid level on computed tomography imaging. Although the general differential diagnosis of lipiduria is broad, reported etiologies of lipiduria diagnosed by computed tomography have primarily included chyluria, urine-induced lipolysis, and trauma. We report a case of lipiduria occurring coincidentally with resolution of perivesical fat necrosis in a patient after partial right hemicolectomy for B cell lymphoma.