Prenatal diagnosis of hemoglobin Bart's hydrops fetalis by HPLC analysis of hemoglobin in fetal blood samples.

Since HbF and HbA are not found in fetuses with Hb Bart's hydrops fetalis the feasibility of prenatal diagnosis of homozygous alpha-thalassemia 1 by fetal hemoglobin typing was examined. Blood samples were obtained from fetuses at 18 to 22 weeks of gestation by cordocentesis in 32 pregnant women at risk of having a child with homozygous alpha-thalassemia 1 (alpha-thal-1). The samples were analyzed by a PCR-based method for the diagnosis of alpha-thal-1 (SEA type) and the proportion of hemoglobin fractions were determined by automated HPLC. DNA analysis showed that 8 of the 32 fetuses were homozygotes for alpha-thal-1, 17 were heterozygous for alpha-thal-1 (alpha-thal-1 trait), and a normal complement of four a-globin genes was found in 7 cases. The Hb typing in fetuses with homozygous alpha-thal-1 showed a peak of unbound Hb (Hb Bart's and Hb Portland) and no HbF, HbA and HbA The alpha-thal-1 trait chromatograms showed unbound Hb, pre HbF, HbF and HbA peaks. The chromatogram of normal fetuses showed HbF and HbA peaks without HbA2. In these cases the HbA proportion is between 3% and 10% with no apparent differences between the 18h and 22nd week of gestation. As the analysis of fetal Hb types by HPLC is facile and speedy and the results correspond with those obtained by DNA analysis, fetal Hb typing by automated HPLC is a convenient prenatal diagnostic method for homozygous alpha-thal-1. The method is recommended for prenatal diagnosis in populations with a high frequency of alpha-thal-1.

Prenatal sonographic markers of trisomy 21.

OBJECTIVE: To describe the sonographic characteristics of fetuses with trisomy 21. DESIGN: A prospective descriptive analysis. SETTING: Department of Obstetrics and Gynecology, Faculty of Medicine, Maharaj Nakorn Chiang Mai Hospital, Chiang Mai University. SUBJECTS: Pregnancies at risk of trisomy 21 between 14-27 weeks' gestation. RESULTS: Thirty-six fetuses with subsequently proven trisomy 21 were prenatally evaluated by ultrasound in the second trimester. The main indications for detailed ultrasound examinations were advanced maternal age and abnormal findings on routine ultrasound. All of them had chromosome analysis by amniocentesis or cordocentesis. Nineteen (52.78%) had one or more abnormal findings. The common sonographic findings included thickened nuchal fold (33.33%), short femur (19.44%), and mild pyelectasis (22.22%). The other uncommon abnormalities included major anomalies (cardiac malformations, ventriculomegaly, duodenal atresia, esophageal atresia), hyperechoic bowel, echogenic intracardiac foci, abnormalities of extremities. In this study, rare minor markers but more specific markers including sandal gap, clinodactyly and mid-phalanx hypoplasia of the fifth finger were demonstrated. CONCLUSION: About half of the fetuses with trisomy 21 had abnormal sonographic findings in the second trimester. The most common marker was thickened nuchal fold. Although prenatal ultrasound can not permit a definite diagnosis of trisomy 21, about half of them have sonographic markers, warranting cytogenetic testing.

Prenatal diagnosis: 10-year experience.

To evaluate the indications and results of prenatal diagnosis of the high risk pregnant women attending the antenatal care clinic at Maharaj Nakorn Chiang Mai Hospital, Chiang Mai University during 1988-1998, we analysed 2,315 amniocenteses, 1,000 cordocenteses, and 11,895 obstetric ultrasound examinations. Among the amniocentesis group, 2,017 cases (87%) were done with the indication of advanced maternal age. The prevalence of major abnormal fetal chromosomes among high risk pregnancies was 1:58. Of 1,000 cases with cordocentesis, the most common indication was fetal risk of severe thalassemia (658 cases; 65.8%) and followed by fetal risk of chromosome abnormalities (272 cases; 27.2%). In the group of cordocentesis for diagnosis of thalassemia, 99 and 49 pregnancies were affected with Hb Bart's disease and homozygous beta-thalassemia, respectively. Thirty three cases with indication of chromosome analysis had fetuses with abnormal chromosomes. The major indications of ultrasonography included suspicion of intrauterine growth restriction (IUGR), determination of gestational age and screening anomalies, respectively. In conclusion, our extensive experience has enabled us to prenatally detect most fetuses with severe thalassemia, and fetuses with abnormal chromosomes as well as anomalies in a significant number, contributing a great deal to our population. Therefore, we recommend that systematic prenatal diagnosis, either amniocentesis, cordocentesis or ultrasound should be provided to every high risk pregnant woman for a healthy newborn.

Study of intrauterine growth from birthweight at Maharaj Nakhon Chiang Mai Hospital.

Intrauterine growth curve and normogram for newborns at Maharaj Nakhon Chiang Mai Hospital are constructed. Birthweight at various gestational weeks of deliveries were determined within 24 hrs after birth. All 1,311 Thai pregnant women selected, fitted the criteria of inclusion deliveries at Maharaj Nakhon Chiang Mai Hospital from May 1983 to April 1991 (8 yrs). Their gestational age distribution was between 28 wks to 42 wks. Clinical status at birth was satisfactory. There were no obstetric or medical complications during pregnancy. Mean birthweight and standard deviation of newborns for each gestational age at delivery were calculated and presented in tabular and graphic form. Mean birthweight for 40 wks of gestation was 3.144 +/- 382 g. In addition, normogram of 10th, 50th, 90th percentile ranks of birthweight for each gestational age was constructed. These values may be useful as baseline data of intrauterine growth curve to evaluate fetal growth in our population.