[Role of fetal urine sampling in the prenatal diagnosis of malformative uropathies].

Objective: To define the diagnostic and therapeutic value of foetal urine sampling (FUS).

Material And Method: Between 1996 and 2001, FUS was performed in 16 patients for three indications: assessment of renal function (Group 1, n = 12), diagnosis of a cystic mass (Group 2, n = 2), prevention of dystocia (Group 3, n = 2). The anomaly was detected by ultrasound. Urine was aspirated from the two renal pelves and/or bladder, or the cystic mass in the other cases. b2-microglobulin and urinary sodium were assayed and karyotyping was performed at the same time.

Results: 20 FUS were performed In 4 cases, two samples were taken at an interval of 2 weeks. No complications were observed. Group 1: 9 pregnancies were terminated for potential renal failure (6 posterior urethral valves (PUV), 1 Prune Belly syndrome, 2 cases of recessive polycystic kidney disease (PKD). Three pregnancies were continued for 2 foetuses with normal renal function (1 PUV, 1 ureterocele) and one foetus died with severe renal failure (bilateral hydronephrosis). Group 2: one termination of pregnancy was performed in a case of hepatic cyst with portobiliary dysplasia and a giant bladder diverticulum was operated. Group 3: in both cases, evacuating aspiration allowed normal delivery of one live infant (left polycystic dysplasia), and one neonatal death from megabladder-megacolon syndrome.

Discussion: The value of FUS is controversial. We usually performed this examination for assessment of renal function. The results of FUS are useful for management decisions when they are in favour of potential impaired renal function. They usually confirmed the ultrasound results that already indicated a poor prognosis and they did not change the decision already based on ultrasound findings in any of our cases. For the diagnosis of cystic masses, after drainage of the mass, FUS facilitated investigation of the urinary tract and adjacent organs. When FUS was performed during labour, it reduced the size of the mass and the abdomen, allowing vaginal delivery with a better ventilatory adaptation of the infant.