Antenatal evaluation of an encephalocele in a dizygotic twin pregnancy using fast magnetic resonance imaging.

We report a case of an encephalocele in a dizygotic twin pregnancy, following ovulatory induction. In the involved fetus, an abnormal shadow like an encapsulated-solid tumor located on the occiput was found by routine maternal transabdominal ultrasonography at 17 weeks of gestation. The parents did not accept induced abortion because of the presence of another fetus with no abnormality on ultrasonography. At 35 weeks of gestation, transabdominal ultrasound examination showed a large occipital cyst, composed of protrusive fetal brain and cerebrospinal fluid. Fast-scanning magnetic resonance imaging delineated more clearly the inside of the abnormal lesion and thus allowed confirmation of the putative diagnosis of fetal encephalocele during pregnancy. Surgical report was possible in this case, and the patient had no severe physical or neurological abnormalities 10 months after birth. Since the prognosis appears to depend primarily on how prominent the brain tissue is inside the herniated sac, this approach had benefit for clinical decision making.