Prenatal diagnosis of gall bladder anomalies—report of 17 cases

We describe here 17 cases of fetal gall bladder anomalies, detected as early as the 14th week of gestation, out of 10 016 fetal systemic examinations performed by us in the last 6 years (015 per cent). In seven cases, agenesis of the fetal gall bladder was detected. The diagnosis was confirmed by post-abortal examination in five cases and in two post-partum. In six other cases, a left-sided gall bladder and in one case, a ‘floating’ gall bladder were detected at 15 weeks' gestation. In two cases, a septated or bilobed gall bladder was visualized. None of these 15 cases was dyskaryotic, but in five cases, two with agenesis and three left-sided gall bladders were associated with other fetal malformations. In two other cases, the gall bladder appeared dysmorphic on sonographic examination and in both of them intrauterine growth retardation and other anomalies were detected. Trisomy 18 was diagnosed by amniocentesis in one of them. According to our experience, failure to visualize the fetal gall bladder by the 15th gestational week is diagnostic of its absence and should raise the differential diagnosis between gall bladder atresia, which has a good prognosis, and external biliary atresia, which has a poor prognosis. Further experience is needed to characterize the various gall bladder malformations and their prognosis.     

Maternal urinary β-core fragment of hCG/creatinine ratios and fetal chromosomal abnormalities in the second trimester of pregnancy

Our aim was to evaluate the potential value of the ratio of the maternal urinary beta-core fragment of human chorionic gonadotropin (βC-hCG) to creatinine (Cr) in discriminating between normal pregnancies and pregnancies associated with fetal chromosomal abnormalities. We hypothesized that pregnancies with fetal chromosomal abnormalities had abnormal quantities of βC-hCG in the urine. The aims of the present study were to investigate retrospectively whether maternal urinary ratios of βC-hCG/Cr are abnormal in women carrying fetuses with chromosome aberrations and to determine normative median values and a reference range for βC-hCG/Cr between 14 and 19 weeks' gestation. Maternal urinary βC-hCG and Cr concentrations were measured in 150 healthy women from 14 to 19 weeks and compared with ten cases of fetal chromosomal abnormalities matched for gestational age. The preliminary cut-off points corresponded to 0·29 multiple of the normal median (MOM) and 2·83 MOM, which were equivalent to the tenth and 90th centiles of the normal range. Of ten cases of fetal chromosomal abnormalities, one out of one (100 per cent) case with trisomy 18 and three of four (75 per cent) cases of variant 9 chromosome had low βC-hCG/Cr (≤0·29 MOM). One of five (20 per cent) cases with Down syndrome had elevated βC-hCG/Cr (≤2·83 MOM). Urinary βC-hCG/Cr ratios obtained in the second trimester may be useful for improved detection efficiency of Down syndrome, trisomy 18, and inversion of chromosome 9. Second-trimester maternal urinary βC-hCG/Cr should be investigated further as a potential marker for fetal chromosome anomalies.     

Prenatal diagnosis of familial ring 21 chromosome

Ring chromosome 21 is a rare chromosome anomaly often associated with mental retardation and dysmorphic features. Less commonly, the ring chromosome can be familial and associated with a normal phenotype. Phenotypically normal female carriers, however, are at increased risk of having children with Down syndrome, mosaic monosomy 21, and variable duplication or deletion of chromosome 21. Because of the relative mitotic and meiotic instability of ring chromosomes, abnormal cytogenetic findings encountered during prenatal diagnosis may not reflect the true genetic status of the fetus. This is a report of a phenotypically normal female carrier of a familial ring 21 chromosome. Prenatal diagnosis on her twin pregnancy revealed a mosaic 46,XX,r(21)(p13;q22) (77 per cent)/45,XX, – 21 in one fetus and a normal male karyotype in the second. The pregnancy was carried to term. Both infants are completely normal, with a non-mosaic ring 21 karyotype from the lymphocytes of one twin. The diagnostic uncertainty and problematic genetic counselling related to fetal cytogenetic abnormalities are the subjects of this report.     

Alpha-fetoprotein and acetylcholinesterase are not predictive of fetal junctional epidermolysis bullosa,Herlitz variant

Junctional epidermolysis bullosa, Herlitz variant (junctional EB-Herlitz) is a lethal autosomal recessive skin disorder currently amenable to prenatal diagnosis only by direct analysis of fetal skin. However, elevated levels of alpha-fetoprotein, as well as the presence of acetylcholinesterase in amniotic fluid, have been associated with other severe fetal genodermatoses. Fetal skin samplings were performed in ten pregnancies at risk for fetal junctional EB-Herlitz, with three fetuses affected on the basis of electron microscopic detection of blisters within the lamina lucida and abnormal hemidesmosomes. In neither affected nor unaffected pregnancies were maternal serum or amniotic fluid alpha-fetoprotein levels elevated. Moreover, alphafetoprotein levels in both maternal serum and amniotic fluid were not statistically different comparing affected and unaffected fetuses. Acetylcholinesterase was not present in the amniotic fluid samples of the three affected pregnancies. Unlike other severe fetal genodermatoses, neither alpha-fetoprotein nor acetylcholinesterase was predictive of junctional EB-Herlitz.     

Follow-up and pregnancy outcome after a diagnosis of mosaicism in CVS

In 2103 consecutive diagnostic chorionic villus samples, examined in a 4-year period in our clinical genetics unit, 26 samples (1.2 per cent) presented chromosomal mosaicism in the direct and/or long-term culture preparations. Only once (46,XX/47,XX,+9) was the mosaicism confirmed in the fetus. In the cytogenetic follow-up studies of the remaining 25 pregnancies, in no cases could the aberration be confirmed in amniotic fluid or fetal tissue. One patient requested a termination after the CVS result. Of the remaining 24 pregnancies, four (16.7 per cent) ended in a spontaneous abortion. These findings suggest an association between placental mosaicism and fetal loss.     

Prenatal echocardiographic diagnosis of right atrial isomerism

A prenatal diagnosis of right atrial isomerism is often inferred through the recognition of a constellation of cardiac anomalies on the four-chamber view or by the detection of visceral heterotaxy and asplenia. However, the actual occurrence of discordance between the arrangement of the atria and thoracic and abdominal organs makes the identification of the morphology of both atrial appendages the only reliable way to make a final diagnosis of atrial isomerism. Three cases of right atrial isomerism with visceral heterotaxy and a complex cardiac defect, diagnosed in utero by cross-sectional and colour flow Doppler echocardiography, are reported. In all the patients, the right atrial isomerism was associated with an atrioventricular septal defect, a single aortic outlet from the right ventricle, and total anomalous venous return. The diagnosis of right atrial isomerism, always confirmed by neonatal re-evaluation and/or by post-mortem examination, was made through identifying two pyramidal atrial appendages in an echocardiographic transverse plane at the level of the atria and of the origin of the great arteries. This report demonstrates that a final intrauterine diagnosis of atrial isomerism is possible, whatever the visceral situs is.     

Prenatal ultrasonographic diagnosis of fetal cerebral ventriculitis associated with asymptomatic maternal cytomegalovirus infection

Cytomegalovirus is the most common cause of congenital viral infection. In utero infection is usually suspected in patients with growth-retarded fetuses or when maternal illness precipitates serological investigations. A case is presented where routine ultrasound examination at 30 weeks' gestation in an asymptomatic patient demonstrated mild fetal ventriculomegaly. Transvaginal ultrasound enabled the visualization of intraventricular adhesions and small periventricular cysts. The suspected diagnosis of in utero cytomegalovirus infection was confirmed by the presence of IgM antibodies in fetal blood and subsequently by isolation of the virus from the infant's urine. The presence of mild fetal ventriculomegaly should prompt transvaginal brain imaging.     

Chorionic mosaicism: Association with fetal loss but not with adverse perinatal outcome

Cytogenetic data from the United States NICHD collaborative study of chorionic villus sampling (CVS) were used to evaluate the clinical significance of chorionic mosaicism. The 10 754 patients with normal cytogenetic results were compared wtih 108 patients (1.0 per cent) with placental mosaicism and 181 patients (1.6 per cent) with pseudomosaicism. Of the pregnancies intended to continue, the pregnancy loss rate was significantly greater in patients with placental mosaicism than in the cytogenetically normal cohort (8.6 vs. 3.4 per cent, p <0.05). However, there was no difference in the frequencies of abruptio placenta, preterm labour or delivery, small-for-gestational-age newborns, pregnancy-induced hypertension, or neonates with Apgar scores less than 7.     

Screening for Down's syndrome in older women based on maternal serum alpha-fetoprotein levels and age: Preliminary results

We report the results of screening for Down's syndrome (DS) in older women using published rate schedules based on maternal serum alpha-fetoprotein (MSAFP) and age. Five hundred and seventeen patients aged 35 years and older, who were referred for a mid-trimester genetic amniocentesis, were first tested for MSAFP and then underwent an amniocentesis. Individual risks for DS, combining MSAFP and age, were derived using three different published rate schedules. Theoretical selection for amniocentesis was made using the cut-off level of the average collective risk for a 35-year-old woman (1:380 at live birth or 1:270 at amniocentesis). Six affected pregnancies (five with DS and one with trisomy 18), which were diagnosed prenatally, were all found to be at a higher risk than the specified cut-off. These cases would have been diagnosed in any event, using any of the published rate schedules. According to these rate schedules, between 39 and 45 per cent of the patients would be in the lower risk group and therefore would have been counselled not to undergo amniocentesis. Further studies should be conducted in order to reach conclusive screening policies for DS in older women.