The fetal urinoma revisited

Prenatal diagnosis and outcome of fetal urinomas in relation to the underlying etiology

OBJECTIVE

Evaluation of course and outcome of pregnancies with prenatally diagnosed fetal urinoma in a single center over a 20-year period.

METHODS

Retrospective study including all prenatally suspected or diagnosed fetal urinomas. Cases were analyzed by ultrasound findings during pregnancy, comparing urinomas caused by lower urinary tract obstruction (LUTO) and ureteropelvic or ureterovesical junction obstruction (UPJO/UVJO). Course of pregnancy and outcomes were compared according to the underlying etiology.

RESULTS

87 cases of fetal urinomas were identified between 2002 and 2022. The underlying etiology was LUTO in 56.3% and UPJO/UVJO in 43.7%. Complications mainly included oligo- or anhydramnios, thoracic hypoplasia as well as associated renal abnormalities. Postnatally, loss of function (LOF) in kidneys affected by urinomas was seen in 78.6% of children overall, but significantly more often in cases of UPJO/UVJO than in LUTO (86.2% vs. 70.2%, p < 0.05).

CONCLUSION

Association of prenatal urinoma and postnatal LOF of the affected kidney is high, especially in cases caused by UPJO/UVJO. In survivors with urinoma caused by UPJO/UVJO, the general prognosis is excellent if the contralateral kidney was normal. In survivors with urinomas caused by LUTO, long-term prognosis depends on postnatal renal and pulmonary function.

Neonatal urinoma associated with ascites in a newborn with a solitary kidney

Fetal urinomas are often diagnosed in prenatal ultrasonography. The etiology is usually an obstructive uropathy leading to hydronephrosis and increased intrarenal pressure putting future kidney function at risk. Rupture of pyelocaliceal system in such cases may lead to retroperitoneal urinoma or urinary ascites, sepsis, uraemia, and acute renal failure. On the other hand, this may serve as "pop-off valve" mechanism decreasing intrarenal pressure and protecting from definitive kidney function loss. We present a case of a newborn girl with a retroperitoneal urinoma, ascites, uraemia, and obstruction of a solitary right kidney, which was successfully treated minimally invasively through peritoneal and retroperitoneal drainage and intubation of the right ureter with a DJ stent shortly after birth.

Fetal Urinoma Due to Circulatory Disorders in an Umbilical Artery: Case Report

Fetal urinoma is defined as an encapsulated accumulation of extravasated urine within the perirenal space or retroperitoneum. It is an uncommon finding in prenatal practice, and the vast majority of known cases are strongly associated with the existence of a urinary obstruction, such as posterior urethral valves, ureteropelvic junction obstruction, or ureterocele. We report a unique case of prenatally detected fetal bladder urinoma that occurred in the absence of an apparent obstructive uropathy, but was associated with extensive ischemic necrosis and calcifications of adjacent bladder wall, coexistent with signs of vascular supply decompensation.

Approach to the postnatal sonographic evaluation of prenatally detected abdominopelvic cysts

Prenatally detected abdominal and pelvic masses are commonly cystic in morphology and usually seen on mid-trimester sonography. Sonography is the favored imaging modality for the postnatal evaluation of these lesions in newborns, given its availability, low cost, lack of ionizing radiation, lack of sedation, and high spatial resolution in small patients. The differential diagnosis of abdominopelvic cystic masses in newborns is broad given that they can arise from many organs and may have overlapping features on imaging. This article illustrates an approach to the postnatal sonographic evaluation of prenatally detected cystic abdominal and pelvic masses based on their anatomic location and distinctive sonographic characteristics, which can aid in an accurate diagnosis and guide appropriate management.

Prenatal extravasation of urine seems to preserve renal function in boys with posterior urethral valves

INTRODUCTION

A posterior urethral valve (PUV) may lead to extravasation of urine, resulting in prenatal ascites and/or perirenal urinoma. Extravasation has been presumed to act as a pop-off mechanism, preserving renal function, but previous reports addressing this presumption have been inconclusive.

AIM OF STUDY

The present study compares renal function in patients with PUV with and without extravasation.

MATERIAL AND METHODS

Sixty boys with a confirmed diagnosis of PUV as neonates (gestational age [GA]<44 weeks) throughout 2001-2016 were included. Clinical data were collected from medical records. Renal function was assessed by nadir plasma creatinine, creatinine at the last follow-up, and glomerular filtration rate (GFR) at the last follow-up. The GFR was estimated using the Schwartz formula. Renal function was classified according to the kidney disease: improving global outcomes (KDIGO) guidelines' grades of chronic kidney disease (CKD). Glomerular filtration rate > 90 ml/min/1.73m² at the last follow-up was classified as normal renal function.

RESULTS

Twelve patients (20%) had ascites and/or urinoma, and 48 (80%) did not. GA and birth weight were not different in patients with and without extravasation. PUV was suspected from prenatal ultrasound findings in 66.7% of the patients in both groups. Median nadir creatinine was 21 (range, 11-33) μmol/L in boys with ascites/urinoma, and all values were within the age-adjusted reference values. Nadir creatinine was 23 (14-199) μmol/L in boys without extravasation, and it was above the normal range in 14 boys. The incidence of elevated nadir creatinine was significantly different in the two groups (p < 0.025). One of the 12 patients with extravasation developed chronic renal failure (CKD 3). In the group of 48 patients without extravasation, 20 (42%) had chronic renal failure grade 2-5, and among these, 5 patients have had a renal transplant (CKD grade 5). The prevalence of CKD grade 2-5 was statistically different in the two groups (p = 0.03). These findings are presented in the summary figure.

CONCLUSION

Extravasation of urine was found in 12 of 60 (20%) boys with PUV. These patients had significantly lower prevalence of CKD at the last follow-up than patients without extravasation. This finding is important in prenatal counseling. It also indicates that prenatal decompression of the bladder and upper tract is beneficial in patients with PUV, which is relevant to the discussion of prenatal intervention in these fetuses.

Ultrasound follow-up of an unusual giant urinoma in a newborn

Urinoma, defined as an encapsulation of urine caused by urine extravasation into the perirenal space either through rupture of a calyceal fornix or a tear in the renal parenchyma, is an uncommon finding in prenatal diagnosis and the neonatal period. Urinoma can be associated with any urinary tract obstruction, or, as reported in several published cases, related to vesicoureteral reflux, kidney dysplasia, or complication arising during amniocentesis. We report on a newborn with a perinatal urinoma, with initial slight corpusculated fluid associated with nonobstructive and nonrefluxing megaureter, and no signs of kidney dysplasia. Close sonography follow-up of the urinoma allowed complex differential diagnoses, including cystic, septated, and solid perirenal masses, due to dissimilar and peculiar ultrasound images during urinoma evolution stages.

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.

Fetal urinoma: A case report and review of the literature

Fetal urinomas are a rare but important sonographic finding. Urinomas are peri‐renal collections of urine, formed after the rupture of the kidney secondary to an underlying urinary tract obstruction or trauma. Diagnosis antenatally is important for ongoing monitoring and postnatal follow up as their presence may indicate reduced or absent kidney function in the affected kidney.

Lower urinary tract obstruction in the fetus and neonate

This article summarizes the most recent literature regarding congenital lower urinary tract obstruction in the fetus and newborn. Lower urinary tract obstruction is a heterogeneous group of rare diagnoses that have significant potential for in utero mortality and long-term morbidity in survivors. The diagnosis and management of the most common causes are reviewed. In addition, the current state of prenatal intervention for congenital lower urinary tract obstruction is discussed.