969

We believe that our improved success rate is directly attributableto the change in technique. The use of anaesthesia renders the childrelaxed, still, and pain-free, thereby facilitating the procedure. Inonly 1 case in group 2 was hydrostatic reduction attempted withoutsedation and this was unsuccessful. We have no doubt that,provided there are no contraindications, attempted hydrostaticreduction is safe, effective, and the treatment of choice in acuteintussusception in childhood.

Leicester Royal Infirmary,Leicester LE1 5WW

H. L. SMITHA. C. LAMONTP. G. F. SWIFT

1. Poston GJ, Singh MP Management of acute intussusception in childhood Lancet

1985; ii 1118.2 Liu KW, MacCarthy J, Guiney EJ, Fitzgerald RJ. Intussusception. Current trends in

management Arch Dis Child 1986, 61: 75-77.3 Sterner GM. Essential paediatric radiology for radiologists and casualty officers

Oxford: Blackwell, 1983.4. Dennison WM, Shaker M. Intussusception in infancy and childhood Br J Surg 1970,

57: 679-84.

SECOND TRIMESTER CHORIONIC VILLUS

(PLACENTAL) BIOPSY

SIR,-Mr Nicolaides and his colleagues (March 8, p 543) reportsix cases of successful prenatal diagnosis by placental biopsy in thesecond or third trimester (five cases of fetal karyotyping and onewith a positive diagnosis of sickle-cell anaemia). We report a case ofsecond-trimester exclusion of aI-antitrypsin (al AT) deficiency byDNA analysis of placental biopsy material.The woman had a daughter with al AT deficiency (PiZZ) in whom

severe cirrhosis of the liver developed; at the age of 7 years anattempt at constructing a portacaval shunt was unsuccessful. Inthree subsequent pregnancies the woman underwent fetal bloodsampling by fetoscopy in the 18th to 20th weeks of gestation (al ATphenotypes can be determined in fetal blood but not in culturedamniotic fluid cells’). Two of the fetuses were affected and thesepregnancies terminated; in the other pregnancy the fetus was notaffected but miscarriage occurred 3 days after fetal blood sampling.In the 15th week of her fifth pregnancy the woman sought fetalblood sampling again. She was informed of the possibility ofprenatal diagnosis by placental biopsy (at that time we had

successfully done such biopsies in six cases of elective pregnancytermination in the l6th to 21st week). She agreed to this proceduresince it seemed that a diagnosis could be established before fetalmovements were perceptible. In week 16, a placental biopsyspecimen was obtained by transabdominal aspiration through a 19gauge (1’ 0 mm) needle and sent by a courier to the laboratory of theHospital for Sick Children, Toronto, Canada for analysis of al ATusing genomic probes.2 The fetus was found to be non-affected. 2weeks after sampling the pregnancy is continuing uneventfully.We find that aspiration biopsy from the large second-trimester

placenta is easy and agree with Nicolaides et al that placental biopsyneed not be restricted to the first trimester.

We thank Dr Diane Wilson Cox for the DNA analysis.

Department of Obstetrics and Gynaecology,University Hospital,S-221 85 Lund, Sweden

BJORN GUSTAVIIHELÉNE EDVALLELISABETH SVALENIUSKERSTIN DAHLANDERCONNIE JORGENSEN

1 Jeppsson JO, Cordesius E, Gustavii B, et al. Prenatal diagnosis of alpha -antitrypsindeficiency by analysis of fetal blood obtained at fetoscopy. Pediatr Res 1981, 15:254-56

2 Cox DW, Mansfield T Prenatal diagnosis for alpha1-antitrypsin deficiency. Lancet1985, i: 230.

SIR,-Mr Nicolaides and colleagues present data on the value offetal karyotyping in apparently non-lethal malformations (Feb 8, p283) and the use of placental biopsy to obtain a fetal karyotyperapidly during the second or third trimester (March 8, p 543). Ourexperience oftrisomy 18 indicates that the development of a safe andreliable technique for determining fetal karyotype during the thirdtrimester would be of great value when planning the mode of

delivery of babies with intrauterine growth retardation (IUGR). Inthe six years 1980-85 21 babies with trisomy 18 were born inLeicestershire. 11 were delivered by caesarean section, elective in 4and emergency in 7. In 9 of these 11 cases IUGR and/or poorplacental function were noted before labour or elective section. Ourobservation confirms earlier reports of a high incidence of deliveryby caesarean section in trisomy 181,2 and illustrates the potentialvalue of the techniques outlined by Nicolaides et al. It has beenestimated that 3% of growth-retarded newborn babies have a

chromosome abnormality,3 so IUGR is likely to be a better markerfor cytogenetic abnormality than advanced maternal age or previoushistory of non-disjunction.Department of Child Health,Leicester Royal Infirmary,Leicester LEI 5WW

J. P. COOKI. D. YOUNG

1. David TJ, Glew S. Morbidity of trisomy 18 includes delivery by caesarean section.Lancet 1980; ii: 1295

2. Schneider AS, Mennuti MT, Zackai EH. High cesarean section rate in trisomy 18births a potential indication for late prenatal diagnosis Am J Obstet Gynecol 1981;140: 367-70

3 Defawe G, Le Marec B, Grall JY, et al Retard de croissance intra-utérin et aberratonschromosomiques. J Gynécol Obstet Biol Repr 1979; 8: 731-34.

SiR,-Like Mr Nicolaides and his colleagues we have foundtransabdominal chorionic villus sampling useful for confirming thefetal diagnosis ofhaemoglobinopathy at the time of second trimestertermination of pregnancy. However, the same approach should beconsidered in all late therapeutic abortions where fetal diagnosismay in future be by DNA analysis. Placental material is oftenunsuitable for analysis after late terminations because of

degradation of DNA. Villi from a homozygote fetus will allow acomplete family study so that the at-risk couple can be counselled.This approach has encouraged couples to take advantage of firsttrimester diagnosis of the haemoglobinopathies in subsequentpregnancies, but it is equally true for other genetic conditions.Another indication is late intrauterine death where fetus and

placenta are also usually unsuitable for satisfactory fetal

karyotyping after death.

Department of Obstetricsand Gynaecology,

Faculty of Clinical Sciences,University College London,London WC1E 6HX

D. MAXWELLB. MODELLM. PETROUR. H. T. WARD

CHORION VILLUS SAMPLING AND RANDOMISATION

SIR,-Recent correspondence has highlighted concern about theproblems and desirability of doing a randomised trial to compare therisks of chorionic villus sampling (CVS) and amniocentesis. FromJanuary, 1985, women in Oxfordshire seeking prenatal diagnosis,possibly by CVS, were counselled about possible risks of CVS andamniocentesis and were then invited to enter our own trial and;since July, 1985, the Medical Research Council’s multicentre trialof CVS, which allotted them randomly to prenatal diagnosis by CVSor amniocentesis. Total freedom of choice was acknowledged,however, and of 65 women none volunteered to be randomised.They all asked for CVS or for amniocentesis:

Requested Volunteered

Requested ammo- to be

IndIcatIOn for test CVS centesis randomisedAdvanced age 30 16 0Previous affected

pregnancy* 9 1 0

X-linked disorder 5 0 0

Parental translocation 3 0 0

Other 1 0 0

Total ’

48 17 0

*Termmanon or delivery of a pregnancy with aneuptoidy, usually tnsomy 2 1.

Women with a high risk of a positive diagnosis and those withexperience of an affected pregnancy almost invariably asked forCVS while those at lower risk requested CVS or amniocentesis inthe ratio 2:1.CVS is an invasive procedure done at a stage of pregnancy after

which much fetal and placental development occurs. The effects of