Circumvallate placenta

Did You Know?

• On ultrasound, a normal placenta appears complete and uniform with a slightly shiny, translucent fetal surface; a circumvallate placenta may show irregular edges, uplifted margins, or placental sheets.
• In a 1994 study, five experienced sonologists were all unable to properly detect circumvallate placenta on ultrasound, indicating that prenatal sonographic criteria are not reliable for screening.

Signs and symptoms

A circumvallate placenta does not always produce symptoms during pregnancy, making diagnosis difficult in asymptomatic mothers. When symptoms occur, vaginal bleeding is a common sign, especially during the first trimester; one study of 92 women found significantly higher rates of vaginal bleeding across all trimesters compared to controls, though the small sample size may limit generalizability. Bleeding tends to arise where the placenta is exposed because the chorionic plate is smaller than the basal plate. Inhibited fetal growth is another sign, resulting from reduced blood and nutrient supply; physicians investigate when a fetus does not meet growth expectations. Premature rupture of membranes (PROM), particularly when accompanied by second-trimester vaginal bleeding, raises suspicion of circumvallate placenta. The condition is also associated with higher rates of placental abruption, low birth weight, premature delivery, perinatal death, and fetal abnormalities. Low birth weight reflects inadequate nutrition and blood flow during pregnancy.

Cause

The cause of circumvallate placenta is unknown, and no major preventive measures exist to reduce its risk. It is not a genetic disorder. Proposed potential causes include reduced amniotic fluid pressure, circumferential hemorrhage, and superficial or deep implantation of the embryo within the uterine wall, but these mechanisms are not well understood. Certain factors may increase the risk of developing circumvallate placenta or other pregnancy complications. Hypertensive medical conditions, such as hypertension, affect about 10% of pregnancies in the United States and contributed to approximately 6.8% of maternal deaths from 2011 to 2015; women with hypertension may be prescribed anti-hypertensive medications and advised to monitor blood pressure. Maternal age is another risk factor: advanced maternal age (35 years or older) is linked to increased risks of maternal mortality, preeclampsia, restricted fetal growth, and fetal distress, while teenage pregnancy is associated with higher risks of endometriosis, postpartum hemorrhage, and mild preeclampsia compared to mothers in their 20s.

Treatment and management

There is no cure or specific treatment to restore a circumvallate placenta, but management focuses on reducing the risks of complications. If diagnosed during pregnancy, physicians may recommend more frequent growth checks to monitor fetal growth; if growth is unsatisfactory, premature delivery may be advised, with cesarean section often preferred over vaginal delivery. For placental abruption, management includes frequent growth checks, hospital bed rest, early delivery, and emergency cesarean section if needed; IV fluids and blood transfusions may be given to address severe blood loss. If oligohydramnios occurs, amnioinfusion may be considered to replenish amniotic fluid and help prevent underdevelopment of the lungs. Consistent fetal monitoring by a licensed physician can help prevent or reduce the effects of complications. Healthy lifestyle choices, a balanced diet, adequate rest, and cessation of alcohol and tobacco use may also help prevent the condition and its associated complications. In threatening situations, emergency cesarean section is often recommended.

Research

Placental pathological studies have contributed significantly to obstetric literature. Research comparing patients with circumvallate placenta to those with normal placentas has found significantly higher rates of preterm birth, oligohydramnios, placental abruption, low birth weight, and fetal death in the circumvallate group. A case study reported an observation of the correlation between circumvallate placenta and battledore insertion, an abnormal umbilical cord insertion occurring in about 7% of pregnancies that can cause intrauterine growth restriction, fetal distress, and fetal death due to restricted blood flow. In that case, a 22-year-old woman at 28 weeks and 2 days of gestation, with two prior miscarriages, presented for routine third-trimester screening; a previous normal second-trimester screening had not identified placental abnormalities, decreased fetal size, or abnormal cord insertion, and she had no vaginal bleeding during the current pregnancy.