Diabetes with Polyhydramnios

Diabetes with polyhydramnios is diabetes in pregnancy with excess amniotic fluid, defined as amniotic fluid index above 24 cm or deepest vertical pocket above 8 cm. Fetal hyperglycaemia causes polyuria and increased fluid. It matters because it causes preterm labour, malpresentation, cord prolapse, abruption and postpartum haemorrhage, and can hide a fetal anomaly.

• Most common with poorly controlled diabetes.
• Usually appears after 28 weeks.
• Other causes must still be excluded.

Women have a tense, large abdomen, breathlessness, discomfort and fetal parts that are hard to feel, and sometimes preterm contractions. Fundal height is more than 3 cm above gestation.

• Fetal parts hard to feel, fetal heart sounds distant.
• Leg and vulval oedema.
• Differential diagnosis: macrosomia, multiple pregnancy, fetal anomaly (oesophageal atresia, anencephaly), fetal anaemia, infection, idiopathic polyhydramnios.
• Complications: preterm labour, premature rupture of membranes, malpresentation, cord prolapse, placental abruption on rupture, postpartum haemorrhage, respiratory compromise.

The approach is ultrasound with a search for the cause.

• Ultrasound: amniotic fluid index above 24 cm (mild 24 to 29.9 cm, moderate 30 to 34.9 cm, severe 35 cm or above) or deepest pocket above 8 cm.
• Detailed anomaly scan and fetal heart scan; growth scan.
• Capillary glucose profile and HbA1c.
• Indirect Coombs test, TORCH and syphilis serology, full blood count.

The principle is tight glucose control, treatment of symptoms and planned delivery.

• Supportive: rest; admit for severe symptoms; counsel on warning signs of preterm labour; delivery in a facility with neonatal care.
• Pharmacological: intensify insulin by 2 units or 10 percent every 2 to 3 days (isophane insulin 0.2 units/kg at bedtime plus soluble insulin 0.1 units/kg before each meal as the starting plan); indomethacin 25 mg oral 6-hourly for up to 48 hours before 32 weeks for severe symptomatic cases, with ultrasound review of the ductus arteriosus; betamethasone 12 mg IM twice, 24 hours apart, if delivery is likely before 34 weeks, with insulin increased by 25 to 40 percent for 72 hours; oxytocin 10 IU IM after delivery of the baby and infusion 20 IU in 1 litre sodium chloride 0.9 percent at 125 mL/hour for 4 hours for prevention of haemorrhage.
• Procedures: therapeutic amnioreduction by ultrasound guided needle for severe symptoms, removing up to 2 litres at no more than 1 litre every 20 minutes; controlled amniotomy in labour to prevent cord prolapse.
• Special groups: neonates feed within 30 minutes, check glucose at 2 to 4 hours, treat glucose below 2.6 mmol/L with dextrose 10 percent 2 mL/kg IV over 10 minutes; check for oesophageal atresia if the baby has frothing.
• Red flags: abdominal pain, contractions, rupture of membranes, breathlessness, reduced fetal movements.
• Follow-up: scan every 2 weeks; delivery at 38 to 39 weeks; glucose review weekly.