CYSTIC HYGROMA - COMPARISON BETWEEN PRENATAL AND POSTNATAL DIAGNOSIS

Antenatal diagnosis of congenital malformation often leads to opportun ities for intervention in the pregnancy that may have a profound effec t on the outcome of the fetus, The accuracy of the diagnostic techniqu e is a critical factor in judging the appropriateness of such interven tions. This article reports the current accuracy of prenatal ultrasoun d diagnosis of cystic hygroma (CH) in a region with a population of 3. 5 million and an annual birth rate of 52,000. During a 32-month period (to December 1994), 113 diagnoses of CH were reported to the South Ea st Thames Regional Congenital Malformation Registry. Eighty-nine diagn oses were made prenatally and 24 were made postnatally (at delivery or postmortem). The number of confirmed cases of CH was 52 (46% total di agnoses). The prenatal diagnoses were established at a mean gestationa l age of 19 weeks, Fifty-six (63%) pregnancies with a prenatal diagnos is of fetal CH were terminated; in only 25% of these was the presence of CH confirmed after termination. Overall, of the 89 prenatal diagnos es, 28 (32%) were confirmed, 45 (50%) were incorrect, and 16 (18%) cou ld not be confirmed or refuted. Only 24% of fetuses with a prenatal di agnosis of CH were live born. The survival rate at 1 year for the live -born infants with CH in this series was 88%. The diagnosis of fetal C H has a recognised association with chromosomal abnormalities, and con sequently may lead to termination of the pregnancy, A potential error rate of almost 70% in the prenatal ultrasound diagnosis of this condit ion requires clinicians to adopt a more cautious approach to the manag ement of the fetus with ''cystic hygroma.'' (C) 1996 by W.B. Saunders Company