Double-positive maternal serum screening results for down syndrome and open neural tube defects: An indicator for fetal structural or chromosomal abnormalities and adverse obstetric outcomes.
OBJECTIVE
The study was designed to evaluate whether double positive maternal serum screening results for Down syndrome and open neural tube defects indicate an increased risk of adverse perinatal outcome.


METHODS
A retrospective case-control study was conducted. In a cohort of 170,394 women who underwent maternal serum triple screening in Ontario, Canada, between October 1995 and September 1998, 189 women received positive screening results for both Down syndrome and neural tube defects. Each case was matched to 5 control subjects who had negative screening results for test center, maternal age, and specimen date. The risks for adverse perinatal outcomes were compared.


RESULTS
Women with double-positive screening results had significantly higher risks of having fetuses with structural abnormalities (odds ratio, 14.5) and chromosomal anomalies (odds ratio, 36.3). They also had higher risks of having preeclampsia (odds ratio, 6.7), small-for-gestational age (odds ratio, 9.7), preterm delivery (odds ratio, 5.9), miscarriage, and intrauterine fetal death (odds ratio, 11.8).


CONCLUSIONS
Double-positive maternal serum screening results are associated with fetal structural and chromosomal abnormalities and/or adverse pregnancy outcomes. Close fetal and maternal surveillance are indicated when such pregnancies are identified.
Chitayat
David
D
Prenatal Diagnosis and Medical Genetics Program, Mount Sinai Hospital, University of Toronto, Ontario, Canada. dchitayat@mtsinai.on.ca
Farrell
Sandra A
SA
Huang
Tianhua
T
Meier
Chris
C
Wyatt
Philip R
PR
Summers
Anne M
AM
D016022:Case-Control Studies; D006063:Chorionic Gonadotropin / Q000097:blood*; D002869:Chromosome Aberrations; D000013:Congenital Abnormalities / Q000175:diagnosis*; D004314:Down Syndrome / Q000175:diagnosis*; D004964:Estriol / Q000097:blood*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D009436:Neural Tube Defects / Q000175:diagnosis*; D011247:Pregnancy; D011256:Pregnancy Outcome; D012189:Retrospective Studies; D000509:alpha-Fetoproteins / Q000032:analysis*
D006063:Chorionic Gonadotropin; D000509:alpha-Fetoproteins; D004964:Estriol