Imaging Monochorionic Pregnancies

▸ Estimating fetal growth by measuring head diameter, abdominal circumference, and femur length is an important aspect of assessing placenta sharing and the availability of nutrients. The abdominal circumference is the single best measurement of fetal nutrient status; a discrepancy at 16 weeks increases the risk for subsequent complications.

▸ Evaluating bladder filling in combination with amniotic fluid volume is an important element of estimating fetal blood volume status.

▸ Research shows that a combined risk assessment in the first trimester and at 16 weeks can predict selective intrauterine growth restriction and twin-to-twin transfusion syndrome—two of the major complications of monochorionic pregnancies—with greater than 80% accuracy.

▸ Doppler ultrasound of the umbilical artery is important for assessing placenta sharing and the presence of hemodynamically significant arterio-arterial anastomoses.