Review Question - QID 107200

Pregnant women with diabetes are at an increased risk of sudden intrauterine death. Intrapartum fetal assessment, consisting of a nonstress test, biophysical profile, or combination of these twice per week until delivery, should begin at 28-32 weeks gestation.

A nonstress test (NST) is an evaluation where external ultrasound monitors are placed on the mother's abdomen to monitor the fetal heart rate. A reactive NST is defined as 2 or more accelerations in 20 minutes, where an acceleration is at least a 15 bpm increase in fetal heart rate for at least 15 seconds. A biophysical profile is a scoring assessment of fetal well-being; it includes 5 components: 1) nonstress test, 2) ultrasound evidence of fetal breathing movements, 3) ultrasound evidence of fetal gross body movements, 4) US evidence of fetal muscle tone, and 5) qualitative assessment of amniotic fluid volume.

Zolotor et al. review prenatal care practices, focusing on gestational (not pre-gestational) diabetes. Gestational diabetes affects 2-5% of pregnancies. Women at risk should be screened with A1C or fasting glucose levels early in pregnancy. All pregnant women should be screened at 24-28 weeks with a 50 gram one hour glucose tolerance test.

Graves reviews antepartum fetal surveillance in pregnancies complicated by diabetes mellitus. Starting at 32 weeks gestation, pregnancies complicated by pre-existing diabetes mellitus should undergo surveillance twice weekly with a nonstress test, biophysical profile, or a combination of these two modalities. Doppler flow studies should not be routinely used in diabetic mothers - this study is more appropriate for hypertensive disease, vascular disorders, and intrauterine growth restriction.

Illustration A shows a reactive nonstress test; note the two accelerations within 20 minutes (the small square boxes are 10 seconds (horizontal) by 10 bpm (vertical)). Illustration B shows the components and scoring of a biophysical profile assessment.

Incorrect Answers:
Answer 1: Ultrasound for fetal growth should be started at 28 weeks gestation and continuing every 4 weeks.
Answer 2: Monitoring fetal kick counts may be acceptable for mothers with diet-controlled (no medicines, insulin, etc) gestational diabetes with good glycemic control. This population is not at increased risk of intrauterine death.
Answer 3: Nonstress testing should be performed twice per week in mothers with diabetes from 28-32 weeks gestation until delivery.
Answer 4: Biophysical profile is an acceptable alternative to nonstress testing; however, it should still be performed twice weekly.