Evaluation of maternal serum dimeric inhibin a as a first-trimester marker of down's syndrome

While second-trimester prenatal screening programmes for Down's syndrome have become established in prenatal care, it would be advantageous to be able to offer screening in earlier preganancy. To this end, we have evaluated a new potential maternal serum marker, dimeric inhibin A, as a possible first-trimester marker. Dimeric inhibin A was measured in propsectively collected maternal serum from 23 cases of Down's syndrome and matched chromosomally normal controls, at 11–13 weeks' gestation. Levels of this protein were significantly elevated in the Down's pregnancies compared with the control pregnancies. The median multiple of the normal median (MOM) for the Down's samples was 2.46 (95 per cent confidence interval: 2.11–3.26, P<0.0001 vs. controls). These results suggest that dimeric inhibin A is a useful discriminator of Down's-affected pregnancies from normal pregnancies in the first trimester and that sensitive screening in combination with maternal age and other possible markers may be practicable in the first trimester.     

Potter's syndrome in the second trimester—prenatal screening and pathological findings in 60 cases of oligohydramnios sequence

Fifty-two second-trimester and eight third-trimester (>28/40) autopsies with clinical or pathological evidence of oligohydramnios sequence (“Potter's syndrome”) were reviewed. Twenty-eight cases had renal anomalies (71 per cent in terminations following prenatal ultrasound), 27 had no renal malformation (35 per cent with chorioamnionitis), and five had external assessments only. In 15 cases, the renal lesion was part of a multiple malformation syndrome. Seven cases had a lesion which either recurred in a sibling in the same family or was a recognized autosomal recessive syndrome. Three cases had an abnormal karyotype, two of which had renal anomalies. Maternal serum alpha-fetoprotein (AFP) did not discriminate between cases with renal malformations and those without. Pulmonary hypoplasia was commoner in third-trimester than in second-trimester cases. External appearance and absent umbilical artery were not reliable predictors of underlying internal anomalies. These findings reflect the shift from postnatal to prenatal diagnosis in modern practice. In this series, mainly second-trimester cases, 50 per cent of cases had no malformations, in a condition which is traditionally associated with renal disease. The high incidence of chorioamnionitis suggests that the mechanism of oligohydramnios is occult amniotic fluid leakage. Prenatal diagnosis of oligohydramnios in the second trimester is dependent on ultrasound scanning and a full post-mortem examination is necessary to identify any underlying fetal cause.     

Prenatal diagnosis of congenital human cytomegalovirus infection

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 ⩾ 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.     

Prenatal diagnosis of bartter syndrome

Bartter syndrome, an autosomal recessive disorder of hyperaldosteronism and increased plasma renin, was suspected in an at-risk pregnancy due to the early occurrence of polyhydramnios. Further establishment of the diagnosis was accomplished by demonstrating increased levels of aldosterone in amniotic fluid and fetal cord blood. Electrolyte levels did not differ significantly from reported controls. It is thus suggested that polyhydramnios is the result of increased fetal urine output in Bartter syndrome and that amniotic fluid aldosterone is a reliable marker for the prenatal diagnosis of this condition.     

Second-trimester unconjugated oestriol levels in maternal serum from chromosomally abnormal pregnancies using an optimized assay

Second-trimester unconjugated oestriol (UE3) levels were measured retrospectively in maternal serum from 78 chromosomally abnormal pregnancies and 390 matched controls using a radioimmunoassay kit (Amersham AMERLEX-M) optimized for use in the second trimester. Reduced levels of UE3 were found in a group of 49 Down's syndrome pregnancies with a median UE3 level of 0·79 multiples of the median (MOM) of the controls. Four trisomy 18 pregnancies had UE3 levels less than 0·7 MOM. There was a highly significant level of correlation between alpha-fetoprotein (AFP) and UE3 levels in the controls (r = 0·25, P <0·01), the Down's syndrome pregnancies (r = 0·44, p 0·01), and the other chromosome abnormalities (r = 0·61, p0·01). When used as an additional marker to AFP and human chorionic gonadotrophin in screening for Down's syndrome, UE3 does not appear to add to the sensitivity of such screening.     

Alpha-fetoprotein levels and yolk sac size in the first trimester of pregnancy

Transvaginal ultrasound measurement of the yolk sac and transvaginal amniocentesis were carried out on 94 women prior to first-trimester termination of pregnancy. Maternal serum and fluids from the amniotic cavity and extraembryonic coelom were analysed for alpha-fetoprotein (AFP). No correlation was found between the yolk sac size and the levels of AFP in any of these sites.     

Prenatal diagnosis of Lesch-Nyhan syndrome: Experience with three fetuses at risk

Our experience with the prenatal detection of the Lesch-Nyhan syndrome (LNS; hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency) in three fetuses at risk is reported. Enzyme activities were measured in cultured amniocytes in two pregnancies, and in tissues and cultures obtained from chorionic villus sampling (CVS) in a third pregnancy. In all tissues the specific activities of HGPRT and adenine phosphoribosyltransferase (APRT) were determined and APRT/HGPRT ratios were calculated. In addition to the enzyme assays, the rate of purine synthesis de novo was assessed in the two amniocyte cultures, and the rate of [¹⁴C]hypoxanthine incorporation into nucleotides and sensitivity to azaguanine were measured in one of the amniocyte cultures. We report the diagnosis of normal fetuses by study of amniocytes in two pregnancies and of LNS using CVS in one pregnancy. In all three cases the diagnosis was confirmed.     

Exophthalmus–prenatal ultrasonic features for diagnosis of Crouzon syndrome

Prenatal real-time ultrasonographic diagnosis of exophthalmus is presented. Diagnosis was made at the 35th week of gestation in a fetus of a patient affected with Crouzon syndrome (craniofacial dysotosis). Recognition of exophthalmus as a part of Crouzon syndrome and the easy visualization of the eye balls and palpebrae in the third trimester made the diagnosis possible.     

Second trimester prenatal diagnosis of the Jarcho-Levin syndrome

The Jarche–Levin syndrome (spondylothoracic dysostosis) is a rare autosomal recessive disorder characterized by a short neck, short trunk and a constricted thorax due to multiple rib and vertebral defects; other visceral malformations are occasionally present. Most cases die in infancy due to respiratory failure. In this report we describe two cases in one family from the United Kingdom. Prenatal diagnosis by ultrasound examination during the second trimester was successfully accomplished in the second case.