Vasa previa: an unusual cause of fetal distress.

Case Report A 24-year-old primigravida was first seen for obstetric care at 13 weeks' gestation. Initially the pregnancy progressed without apparent difficulty, but the fundal height was found to be somewhat small for dates at 38 weeks' gestation. A sonogram obtained at that time showed a 33-week-sized fetus, with all measurements being concordant and no sonographic evidence of intrauterine growth retardation. The biophysical profile was 8/8 (normal movement, tone, respirations, and qualitative amniotic fluid volume), and the placenta was grade m. A repeat ultrasonic scan 3 weeks later, on 12 June 1989, showed a 35.7week-sized fetus, with measurements again concordant; the placenta was now grade IV and mature, and the biophysical profile was still 8/8. The patient was hospitalized for induction on 18 June 1989, at 41 weeks' gestation by dates. Examination showed a vertex presentation with the cervix at fingertip dilatation, anterior, soft, and long, and the fetal head was ballotable. Using a catheter, 0.5 mg of prostaglandin E2 gel was instilled in the cervix. Shortly thereafter, deep variable fetal heart decelerations were noted over a period of 2 to 3 minutes with minimal contractions (Figure 1). Because of the decelerations, the patient was monitored overnight, but no further difficulties were noted. The following day she received oxytocin. There was minimal cervical change over 8 hours, but the fetal heart tracing had been stable. The patient slept through the night.