Increased detection of cystic hygroma: a "technology-induced phenomenon".

In this study, we have determined the increasing rate of detection of cystic hygroma in an urban hospital-based Active Malformations Surveillance Program during 1973-1974, 1979-1980, 1984-1985, and 1989-1990. All affected infants were identified from a review of the findings in either the findings in the pediatricians' examinations, the autopsy reports or the reports of finding in prenatal ultrasonography. The infants were subdivided by maternal transfer status and age (> or = 5 or < 35), the presence of associated chromosome abnormalities and malformations and birth status. Eighty-four affected infants and fetuses were identified, 47 of whose mothers were nontransfers. Among the maternal nontransfers, the prevalence rate of cystic hygroma increased from 0.08/1,000 in 1973-1974 to 1.45/1,000 in 1988-1990. Initially, the diagnosis was made at birth in liveborn or stillborn infants, but by 1989-1990, only by prenatal ultrasonography. Most (71%) of the pregnancies with affected fetuses were terminated by choice following diagnosis with prenatal ultrasonography. A marked increase in the frequency of examination by sonography during pregnancy was observed among a comparison group of women between 1974 and 1989. The progressive increase in the detection of cystic hygroma in this time period was one effect of this more extensive use of prenatal ultrasound, better equipment, and more experienced sonographers.