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Samples of chorionic villi were obtained in the first trimester by aspiration using a cannula passed transcervically under the guidance of real time ultrasound. In initial studies in 47 anaesthetised patients immediately before therapeutic abortion a method was developed giving a success rate of 89%. In 10 patients successful sampling was performed as an outpatient procedure without anaesthesia. In all, seven diagnostic procedures were undertaken and four of the five unaffected pregnancies continued. The technique of chorionic villous sampling using real time ultrasound is simple to learn and yields material for biochemical analysis and chromosomal study without the need for tissue culture. The exact obstetric risk, however, remains to be defined.

Between 1979 and 1990, 170 couples at risk of having children with sickle cell disease, resident in the UK and with a continuing pregnancy, were referred for counselling at the University College Hospital Perinatal Centre. Approximately 50% of the couples, including those where one partner actually had sickle cell disease, requested prenatal diagnosis. This was requested in 82% of pregnancies when the mother was seen in the first trimester of pregnancy and in 49% when she was seen in the second trimester. More than 90% of referred couples who already had an affected child requested prenatal diagnosis. The type of sickle cell disease involved and ethnic group also influenced choice. These results show the importance of detecting and counselling couples at risk before pregnancy whenever possible. (J Med Genet 1992;29:820-3) rently, countrywide, 35 trained counsellors are working in 23 Health Authorities, 12 of them in six Health Authorities in North London (E Anionwu, personal communication). In England and the United States, about a third to a half of at risk couples counselled by a trained person request prenatal diagnosis.78 This suggests that a review of a series of cases may cast light on factors that influence the choices informed couples make. Here we report the results of a review of the records of pregnant women at risk for having children with sickle cell disease counselled at the UCH Perinatal Centre, which offers a regional and national service for prenatal diagnosis of haemoglobin disorders. The results show that choice is influenced by the nature of the genetic risk, ethnic group, experience of an affected family member, and the possibility of diagnosis in the first trimester of pregnancy. Clearly, couples at risk for having children with inherited diseases should be identified and provided with expert counselling either before or at the earliest possible stage of pregnancy.

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Maternal serum levels of human chorionic gonadotrophin and its subunits (intact, alpha, and free beta h CG) and pregnancy-associated plasma protein A (PAPP-A) were measured in 279 women between 8 and 14 weeks' gestation. This group included 23 pregnancies in which the fetus had Down syndrome (DS), diagnosed either at birth or during the second trimester (n = 17) or from chorionic villus sampling (CVS) (n = 6). Normal medians were determined from the 258 apparently normal pregnancies. The median levels of intact hCG (1.4 MOM) and free beta hCG (2.1 MOM) were significantly raised, whereas the median level of PAPP-A (0.39 MOM) was significantly lower in the DS pregnancies when compared with the control group. Levels of alpha hCG were similar in both the control and the DS pregnancies. Analysis of samples taken prior to 14 weeks' gestation demonstrated that only PAPP-A (0.34 MOM) was significantly altered in DS pregnancies. However, after the exclusion of DS cases diagnosed at CVS, the median intact hCG (1.56 MOM), free beta hCG (2.27 MOM), and alpha hCG (1.8 MOM) were all raised in DS pregnancies. This emphasizes the problem of the interpretation of biochemical markers when DS cases are diagnosed at CVS.

Objective Alpha zero (α° or α‐1) thalassaemia is an important genetic risk for women originating from Hong Kong, Singapore, Vietnam, Thailand, the Philippines or South China. Cypriots are also at risk. Carriers of α° thalassaemia trait can be detected by routine haemoglobinopathy screening. When a couple are both carriers, in each pregnancy there is a 25% risk that the fetus will have α thalassaemia hydrops fetalis; this is fatal for the fetus and carries serious obstetric and psychological risks for the mother. Most informed couples at risk request prenatal diagnosis and selective abortion. This study investigates the effectiveness of screening, counselling and prenatal diagnosis for α thalassaemia hydrops fetalis in the UK. Design Retrospective analysis of the notes. Subjects 18 couples attending University College Hospital London for prenatal diagnosis of α thalassaemia hydrops fetalis since 1982. Results The study shows underdiagnosis of both α° thalassaemia trait and α thalassaemia hydrops fetalis leading to avoidable stillbirths and complications in pregnancy. Conclusion We recommend early screening for α° thalassaemia trait for all women of Southeast Asian or eastern Mediterranean origin and the offer of prenatal diagnosis when indicated. The diagnosis of α thalassaemia hydrops fetalis should be considered in women of the relevant ethnic origin who have a stillbirth, neonatal death, abnormal ultrasound findings at fetal anomaly scanning (especially a large placenta), or who develop pre‐eclampsia.

Serum PAPP-A measurements taken from 254 women in the first trimester are reported. Eleven chromosomal abnormalities were detected. The mean serum PAPP-A levels in cases of Down syndrome were 0.44 MOM at 9 weeks gestation, 0.15 MOM at 10 weeks, and 0.29 MOM at 11 weeks. The PAPP-A level at 10 weeks was below those of pregnancies which aborted spontaneously. At 11 weeks, the pregnancies with Down syndrome recorded the lowest PAPP-A levels at that gestation. On this small sample, offering chorionic villus sampling to women with singleton pregnancies and a PAPP-A level below 0.3 MOM (approximately 6.5 per cent of this at-risk group) would have detected all the Down syndrome fetuses at 10 weeks and 50 per cent at 11 weeks without selecting those cases destined to abort. This suggests that serum PAPP-A should continue to be investigated as a potential first-trimester screening test for Down syndrome.

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