SUCCESS RATE OF CYTOGENETIC ANALYSIS AT THE TIME OF 2ND-TRIMESTER DILATION AND EVACUATION

OBJECTIVE: The aim of this study was to determine the success rate of cytogenetic analysis from specimens obtained at the time of second-tri mester termination of pregnancy by dilation and evacuation. STUDY DESI GN: All second-trimester dilation and evacuations performed by a singl e practitioner at a single institution from 1993 through 1995 were eva luated to pick out those patients in whom biopsy specimens were submit ted for cytogenetic analysis. The main outcome studied was the ability to obtain karyotype results for these specimens. RESULTS: Cytogenetic studies were performed on 258 dilation and evacuation specimens with a median gestational age of 18 weeks (range 13-25 weeks). The indicati ons for termination were fetal aneuploidy (n = 88, 34%), sonographical ly diagnosed fetal malformations (n = 82, 32%), intrauterine fetal dea th (n = 67, 26%), oligohydramnios or premature rupture of membranes (n = 16, 6%), and others (hematologic and metabolic disorders, n = 5, 2% ). Successful karyotyping was achieved for 99% of specimens obtained a t second-trimester dilation and evacuation, with 3 failures of growth (1% failure rate). The failures included a 14-week molar pregnancy, an 18-week fetus with Dandy-Walker malformation, and a 19-week intrauter ine fetal death. Of the samples obtained in cases of intrauterine feta l death, 99% (66/67) provided adequate cytogenetic information. CONCLU SIONS: Karyotyping for abnormal second-trimester pregnancies and intra uterine fetal deaths at the time of a dilation and evacuation procedur e has a success rate nearing 100%. In contrast to previous reports, ou r data indicate that it is unnecessary to perform pretermination invas ive karyotyping in patients with abnormal second-trimester pregnancies or intrauterine fetal death who elect to undergo dilation and evacuat ion. Chromosome analysis at the time of termination of pregnancy by di lation and evacuation reduces patient discomfort, risk of infection, a nd cost while still providing reliable and vital cytogenetic informati on for future genetic counseling.