In the study, a 22-year-old woman at 28 weeks and 2 days of gestation, presented for a routine third trimester screening. She was noted to have had 2 prior miscarriages at 17 and 20 weeks. A previous normal second trimester routine screening at 21 weeks of gestation did not identify any structural abnormalities within the placenta, decreased fetal size, or abnormally-appearing umbilical cord insertion. The patient also did not have any episodes of vaginal bleeding during the current pregnancy.Upon presenting for routine screening at 28 weeks and 2 days of gestation, the patient was not exhibiting any signs of active contractions and a cardiotocography was performed as part of routine screening. Cardiotocography is a diagnostic tool used during the third trimester of pregnancy to observe fetal heart rates and presence of uterine contractions. It can also be used to detect signs of any sort of fetal distress. In interpreting the cardiotocography that the 22-year-old pregnant woman had completed, it was noted that the fetus appeared to be much smaller than expected and was exhibiting concerns of decreased amniotic fluid volume, oligohydramnios, and restricted blood flow through the umbilical cord. Cardiotocographic monitoring also noted decreases in fetal heart rate every 25 minutes without contractions. Fetal motion was present, with the placenta appearing enlarged and spherical.Decreases in the fetus heart rate, in addition to the other findings of the cardiotocography, ultimately prompted physicians to deliver the baby via emergency cesarean section without major complications.
In most cases, a circumvallate placenta is not discovered until physical examination of the placenta after delivery of the fetus. For this reason, circumvallate placenta is very difficult to diagnose during pregnancy. On ultrasound, a normal placenta should appear complete and uniform, with the fetal surface of the placenta appearing slightly shiny and translucent. The appearance of a circumvallate placenta on ultrasound may present with irregular edges, uplifted margins, or placental sheets. In a study conducted in 1994, 62 healthy pregnant women were examined with placental sonography for detection of circumvallate placenta. Of the five experienced sonologists who interpreted the placental ultrasounds, all were unable to properly detect and diagnose circumvallate placenta, revealing the difficult nature of circumvallate placenta recognition. Further, these findings indicate that prenatal sonographic criteria used for detection of circumvallate placenta are not reliable enough for screening purposes. Complete circumvallate placenta involves morphological abnormality of the entire dimension of the placenta, while partial circumvallate placenta does not involve the entire placenta but rather a portion of the placenta. Complete circumvallate placenta is very rare, occurring within about 1% of pregnancies, and has been noted to increase the risks of associated complications such as placental abruption, premature childbirth, premature rupture of membranes, perinatal death, and congenital abnormalities. Partial circumvallate placenta is more common but is not found to be as clinically significant as complete circumvallate placenta.The accurate diagnosis of circumvallate placenta during pregnancy can have significant implications in the recognition of patients who are at risk of complications.