THE EFFECT OF AMNIOTIC SHEET ORIENTATION ON SUBSEQUENT MATERNAL AND FETAL COMPLICATIONS

The purpose of this investigation was two-fold, first, to determine th e incidence of amniotic sheets in our obstetric population; and second , to elucidate the maternal and fetal complications associated with th is particular finding. In this retrospective study, we searched the co mputerized records of the ultrasound department for the presence of am niotic sheers in singleton pregnancies from 1 March 1991 to 17 Septemb er 1993. Sonographic criteria for an amniotic sheet included the findi ngs that (1) a reflective membrane attached to the placenta at one end or the other, with measurable thickness, was identified traversing th e amniotic fluid; and (2) the fetus was not attached to the membrane, and fetal ability to move without restriction was ascertained. An amni otic sheet was identified in 79 of 17 553 examinations (0.45%) perform ed between 12 and 28 weeks' gestation. Two subsets of amniotic sheers were identified: perpendicular and not perpendicular. The sheets in th e first subset were orientated perpendicular to the placental surface and were more likely to be associated with an abnormal presentation at delivery (p < 0.001) and a history of pelvic inflammatory disease, bu t not with a history of prior Cesarean section, or previous dilatation and curettage. The second subset of amniotic sheets were non-perpendi cular, either oblique or parallel, in orientation to the placental sur face and were associated with fewer maternal complications. Of the stu dy group, 40.7% had a history of vaginal bleeding. The incidence of va ginal bleeding was not significantly different between those patients with perpendicular or those with non-perpendicular amniotic sheets. We conclude that perpendicular, in contrast to non-perpendicular, amniot ic sheers are more commonly associated with breech presentation at ter m and a past history of pelvic inflammatory disease.