Magnetic resonance imaging of fetal urinoma

Prenatal drainage of fetal urinoma with polyhydramnios: a case report and literature review

The appearance of fetal urinoma is rare in prenatal care, especially when associated with polyhydramnions. Many previous reports have concluded that the visualization of a prenatal urinoma is probably a sign of underlying renal dysplasia or poor function. Thus, the management of the reported cases, conservative treatment or uniroma drainage, has not been unified. In this paper, we present two cases of prenatally detected urinoma with prenatal drainage to improve the prognosis.

The fetal urinoma revisited

The fetal urinoma is a rare but important diagnosis, as it indicates substantial underlying obstruction with implications for the functionality of the affected kidney. This case series describes a single center's experience with the diagnosis and management of fetal urinomas. All 25 cases were diagnosed or referred to our medical center over an 11-year period. Most cases were secondary to either posterior urethral valves or ureteropelvic junction obstruction. Fetal interventions, including percutaneous drainage of the urinoma and cystoscopic alleviation of bladder outlet obstruction, were performed in 4 cases.

The impact of perinatal urinoma formation on renal function: our experience and review of the literature

INTRODUCTION

A urinoma is a fluid mass consisting of extravasated urine in the perirenal space. Its impact on renal function was analysed.

METHODS

All cases of prenatal and neonatal urinoma reported in the literature were analysed as well as two cases recently observed in our department.

RESULTS

A review of all prenatally diagnosed urinomas revealed 25 cases, for a total of 30 renal units. The cause of obstruction was: lower urinary tract (LUT) obstruction in 16 cases (62.5%), upper urinary tract (UUT) obstruction in seven cases (29.5%) and unknown in two cases (8%). A preserved renal function was found in only 30% of all cases. Furthermore, prognosis for renal function was better in posterior urethral valve (PUV) patients than in uretero-pelvic junction obstruction (UPJO) patients. In addition, we analysed 35 published cases of urinoma with a neonatal onset, without prenatal diagnosis, and secondary to LUT obstruction in 27 cases (77%), UUT obstruction in seven cases (20%), while the underlying cause was unknown in one cases (3%). A preserved renal function was observed in 84% of cases with UUT obstruction and in 80% of cases presenting a LUT obstruction.

CONCLUSIONS

Prognosis concerning renal function seems to be mainly related to two factors: age at presentation and underlying diagnosis. Decompression of the urinary tract by urine extravasation produces the best results in terms of preservation of the renal function in LUT obstruction (75% in prenatal and 84% in postnatal cases); UUT obstruction however is associated with a good prognosis in the neonatal period (80% of preserved renal function) but with a severe impairment (only 20% of preserved renal function) in prenatally detected cases.

123I-Metaiodobenzylguanidine accumulation in a urinoma and cortex of an obstructed kidney after surgical resection of an abdominal neuroblastoma

Surgical ureteric injury is rare and often unsuspected for a long time. We present a child in whom an abdominal neuroblastoma was completely excised, but during surgery the left ureter was transected and anastomosed. One month later, during postoperative disease staging, abnormal (123)I-MIBG accumulation was observed in the left renal cortex and the left side of the abdomen. These findings were consistent with acute total obstruction and urinoma formation and were subsequently confirmed by renography and MRI. Despite treatment efforts, a significant amount of left renal mass and function were lost over the following months. These unusual findings are new additions to the literature regarding potential false-positive interpretations of (123)I-MIBG scans.

Antenatal isolated hydronephrosis associated with urinoma

Two cases of prenatally identified urinoma associated with an isolated hydronephrosis are presented, and the pathophysiology and prognosis of this rare condition are discussed. The presence in utero of a peri-renal collection associated with an isolated hydronephrosis seems to be a sign of significant renal dysplasia. These urinomas disappear spontaneously, thus drainage is not necessary, except in the case of compression of surrounding structures. The functional prognosis of these kidneys seems to be most unfavourable.

Fetal urinoma: two new cases and a review of the literature

OBJECTIVE

To evaluate the functional prognosis of kidneys affected prenatally by urinomas.

METHODS

This was a retrospective review of cases of fetal urinoma reported in the literature, as well as two of our own cases.

RESULTS

Twenty-three patients with a prenatal diagnosis of urinoma (five bilateral) were included in the analysis. Postnatal ipsilateral renal function was observed in only six of the 28 renal units (i.e. around 20%).

CONCLUSIONS

Although the precise causes of urinomas are still unknown, this review shows that in the event of a fetal urinoma, the probability of a non-functional dysplastic ipsilateral kidney lies at around 80%. In-utero puncture only appears to be justified in cases where fluid accumulation has mass effects on adjacent major structures.

Renal-related perinephric fluid collections: MRI findings

We retrospectively reviewed MR studies on 10 patients with renal-related perinephric fluid collections who underwent MRI in three institutions between January 2001 and August 2004. All patients underwent MRI of the abdomen and T1-weighted, T2-weighted and serial contrast-enhanced images, including delayed-phase contrast-enhanced images 10-12 min after contrast injection, were obtained. Perinephric fluid collections in 5 patients revealed MRI findings of simple fluid content (i.e., hypointense on T1-weighted images and hyperintense on T2-weighted images). In another 5 patients, a complex perinephric fluid content (i.e., mixed hyper/hypointense on T1-weighted images and mixed hypo/hyperintense on T2-weighted images compatible with blood breakdown products and pus) was observed. In 5 patients, contrast extravasation on late-phase images that was compatible with urine leak was demonstrated. Our results suggest that MRI may determine the content of perinephric fluid collections on noncontrast T1-weighted and T2-weighted images and that contrast extravasation on late-phase images is associated with urine extravasation from renal collecting systems.