Monoamniotic twins: improved perinatal survival with accurate prenatal diagnosis and antenatal fetal surveillance

Our goal was to report our 10-year experience with monoamniotic twins and to compare that experience with cases reported in the literature.

Records of all monoamniotic twin pregnancies managed at the University of Connecticut Health Center from March 1986 to August 1996 were reviewed. A MEDLINE search from January 1966 to August 1996 was performed, and each report was screened for accuracy of diagnosis. Only cases with umbilical cord entanglement of nonconjoined like-sex twins, the obstetrician's confirmation at delivery, or pathologic confirmation of monoamniotic placentation were included. Data collected were as follows: birth outcome, gestational age at delivery, birth weight, gender, Apgar scores, hematocrit, cord knotting, and neonatal complications. Cases from the literature were divided into those with prenatal diagnosis and those without.

Thirteen monoamniotic pregnancies resulting in 26 infants who were born alive were managed at our center. The average gestational age at diagnosis was 16.3 weeks. All had antenatal fetal surveillance including serial sonograms and nonstress tests. The average gestational age and birth weight at delivery were 32.9 weeks and 1669 gm, respectively. Cord entanglement was noted in all cases, with knotting in 8 of 13. Two pairs of 26 newborns had evidence of twin-twin transfusion syndrome. Eight of 13 monoamniotic pregnancies were delivered because of nonreassuring results of nonstress test, two because of preterm labor, two electively because of lung maturity, and one because of intrauterine growth restriction. Two of the 26 infants died in the neonatal period, one of congenital heart disease and one of sepsis and asphyxia. The MEDLINE search revealed 96 articles with a total of 202 sets of monoamniotic twins. Comparison of cases (13 sets) with the historic control group without prenatal diagnosis (77 sets) showed a 71% reduction in relative risk of perinatal mortality.

With accurate prenatal diagnosis, intensive fetal surveillance, and appropriately timed delivery, perinatal survival of monoamniotic twins is improved; it was 92% in this series.