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Seventy-one fetal urine samples were taken from the bladder or renal pelvis of 33 fetuses at 13-36 weeks' gestation with a diagnosis of urinary tract anomaly. Severe isolated hydronephrosis in the absence of an enlarged bladder was the indication for sampling in 12/33 fetuses (26 samples), who were retrospectively classified into three groups: normal, intermediate, and dysplastic, based on the evaluation of postnatal renal function or histology. For all samples, urinary sodium (Na+), calcium (Ca2+), creatinine, beta 2-microglobulin, and N-acetyl-beta-D-glucosaminidase (NAG) were measured. Among the 71 fetal urine samples, both beta 2-microglobulin and NAG correlated inversely with gestational age, Na+, and Ca2+, but not with creatinine concentrations. However, the correlation of urinary beta 2-microglobulin with gestational age was dependent on the Na+ and Ca2+ concentrations, whereas urinary NAG correlated significantly with urinary Na+ and Ca2+, and also with gestational age. In fetuses with isolated hydronephrosis, only Na+, and not Ca2+, was significantly related to both beta 2-microglobulin and NAG. Only Na+ and beta 2-microglobulin were significantly, and similarly, higher in both dysplastic and intermediate kidneys when compared with fetuses with normal postnatal function. If only the last urine sampled was considered, there was overlapping of all parameters in the three groups. In isolated hydronephrosis, only the most extreme forms of renal failure might be suggested by elevated levels of Na+, Ca2+, beta 2-microglobulin, and NAG, without an obvious superiority of any of these parameters.

Fourteen fetuses at risk of Varicella-Zoster virus (VZV) infection underwent prenatal diagnosis at 10-24 weeks' gestation by a combination of chorionic villus sampling, amniocentesis, and fetal blood sampling. Polymerase chain reaction (PCR) was done on fetal and placental tissues, using primers which define a 221 bp region of the gene coding for the 44 kD protein of VZV. Positive cases were further analysed by dot blot hybridization, using radiolabelled DNA probes corresponding to the Hind III fragment VZV genome. The rate of placental/fetal infection was 36 per cent (5/14 fetuses: 2/11 in the first and 3/3 in the second trimester). At post-mortem examination, two aborted fetuses had hydrocephaly and VZV DNA was found in most of the examined tissues. The nine women who tested negative at prenatal investigation delivered healthy neonates whose VZV-specific IgM antibody titres were negative and none of them developed herpes zoster infection. In view of the high frequency of fetal VZV infection and the reported low rate of malformations, the role of invasive prenatal diagnosis in women who acquire the infection in the first half of gestation is mainly that of reassurance when the test is negative.

Fifteen fetuses at risk of congenital human cytomegalovirus (HCMV) infection underwent prenatal diagnosis at 16-30 weeks' gestation by a combination of amniocentesis and fetal blood sampling. HCMV was isolated from the amniotic fluid in six patients, but HCMV-specific IgM was detected in only three of them. Two of the nine neonates, who were delivered following a negative prenatal diagnosis, had congenital HCMV infection diagnosed by virus isolation in the urine. The interval from infection to prenatal testing was 3 and 4 weeks in the two false-negative cases and > or = 7 weeks in the true-positive cases. Although timely testing for HCMV infection allows the option of termination of pregnancy, it may be flawed by false-negative results.