Fetal Growth Restriction with Abnormal Dopplers

Fetal growth restriction with abnormal Dopplers is a small fetus showing raised umbilical artery resistance, absent or reversed end diastolic flow, low middle cerebral artery resistance or an abnormal ductus venosus. It results from placental vascular disease, and the Doppler pattern gives the stage of fetal compromise. It matters because the stage guides surveillance and delivery time.

• Stage 1: umbilical artery pulsatility index above the 95th centile or cerebroplacental ratio below the 5th centile.
• Stage 2: absent end diastolic flow. Stage 3: reversed end diastolic flow. Stage 4: abnormal ductus venosus or abnormal cardiotocography.
• Risk factors: preeclampsia, chronic hypertension, antiphospholipid syndrome, kidney disease, smoking.

Women are usually asymptomatic with a small fundal height, reduced fetal movements or hypertension. The stage cannot be judged clinically.

• Fundal height lag of 3 cm or more.
• Low liquor volume.
• Differential diagnosis: constitutionally small fetus, wrong dates, congenital infection, chromosomal abnormality, fetal anomaly, preeclampsia.
• Complications: stillbirth, fetal acidosis, preterm birth, neonatal death, necrotising enterocolitis, cerebral palsy.

The approach is repeated Doppler staging.

• Umbilical artery pulsatility index, with end diastolic flow classed as present, absent or reversed.
• Middle cerebral artery pulsatility index, cerebroplacental ratio (below the 5th centile or below 1.08), uterine artery pulsatility index, ductus venosus pulsatility index and a wave.
• Estimated fetal weight, abdominal circumference, deepest pocket; cardiotocography with short term variation where available.
• Maternal blood pressure, urine protein, platelets, liver enzymes, creatinine, antiphospholipid antibodies, infection tests.

The principle is to stage the disease, intensify surveillance with each stage and deliver at the stage specific gestation.

• Supportive: Stage 1 outpatient with weekly Dopplers; Stage 2 and above admission after 26 weeks, with twice weekly Dopplers and cardiotocography once or twice daily; daily fetal movement counts; left lateral rest; neonatal team informed.
• Pharmacological: betamethasone 12 mg IM twice, 24 hours apart, between 24 and 34 weeks and 6 days before planned delivery; magnesium sulphate 4 g IV over 20 minutes then 1 g per hour until delivery for 24 hours at most before 32 weeks (stop for absent patellar reflexes, respiratory rate below 12 per minute or urine below 30 mL per hour, with calcium gluconate 1 g IV over 10 minutes for toxicity); labetalol 200 mg oral every 8 to 12 hours (maximum 2.4 g daily) or nifedipine modified release 30 to 60 mg oral once daily (maximum 120 mg) for hypertension; enoxaparin 40 mg subcutaneous daily with aspirin 150 mg oral at night for antiphospholipid syndrome.
• Procedures: delivery at 37 weeks (Stage 1), 34 weeks (Stage 2), 30 to 32 weeks (Stage 3), and at any viable gestation after steroids for Stage 4; caesarean section for Stages 2 to 4; induction for Stage 1 with normal cardiotocography using misoprostol 25 micrograms vaginal 6-hourly (maximum 4 doses) or Foley catheter.
• Special groups: severe preeclampsia needs magnesium sulphate 4 g then 1 g per hour for 24 hours after birth and labetalol 20 mg IV then 40 mg, 80 mg and 80 mg at 10 minute intervals (maximum 220 mg); newborns have glucose checked at 2 hours, and glucose below 2.6 mmol/L is treated with dextrose 10 percent 2 mL/kg IV over 10 minutes then 80 mL/kg per day.
• Red flags: reversed end diastolic flow, abnormal ductus venosus, short term variation below 3.5 ms, decelerations, reduced fetal movements, severe hypertension.
• Follow-up: Doppler weekly at Stage 1, twice weekly at Stages 2 and 3, daily with cardiotocography at Stage 4; growth every 2 weeks; newborn review.