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Number of yolk sacs does not predict amnionicity in early first‐trimester monochorionic multiple gestations
Author(s) -
Shen O.,
Samueloff A.,
Beller U.,
Rabinowitz R.
Publication year - 2006
Publication title -
ultrasound in obstetrics and gynecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.202
H-Index - 141
eISSN - 1469-0705
pISSN - 0960-7692
DOI - 10.1002/uog.2637
Subject(s) - yolk sac , gestation , yolk , medicine , obstetrics , monochorionic twins , gestational age , pregnancy , amnion , amniotic fluid , fetus , biology , embryo , ecology , genetics , microbiology and biotechnology
Objective To determine the relationship between amnionicity and number of yolk sacs before 11 weeks of gestation. Methods Twenty‐two cases of monochorionic multiple pregnancy were scanned before 11 weeks of gestation. There were 21 sets of twins and one of triplets. Amnionicity was determined by visualization of a dividing amniotic membrane between the gestational sacs. The number of yolk sacs was recorded and compared with the presence or absence of a dividing membrane for all fetuses. Results In 17/20 (85%) cases of monochorionic diamniotic twins, two yolk sacs were seen. In 3/20 (15%) cases of monochorionic diamniotic twins, a single yolk sac was seen. In the one case of monochorionic diamniotic triplets, two yolk sacs were visualized. In one case of monoamniotic twins, a single yolk sac was observed. Conclusions In monochorionic pregnancies, the presence of two yolk sacs predicts diamnionicity. However, the use of the number of yolk sacs as a predictor of amnionicity may not be accurate in a small proportion of patients. The diagnosis of monoamnionicity can be made only following a careful search for a dividing amniotic membrane. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.