4.8 Polyhydramnios


Excess amniotic fluid (more than 2 litres at term), commonly due to foetal anomalies. There are two clinical situations:
– In the second trimester: acute polyhydramnios;
– In the third trimester: chronic polyhydramnios.

4.8.1 Acute polyhydramnios (rare but serious)

Diagnosis

– Rapid increase in the size of the uterus
– Painful abdomen, abdominal pressure, dyspnoea
– Distended, hard uterus, foetus cannot be palpated

Usually associated with foetal malformation, sometimes a complicated twin pregnancy.

Management

Do not intervene; let the patient abort or deliver spontaneously.

4.8.2 Chronic polyhydramnios

Diagnosis

– More moderate increase in the size of the uterus, occurring in spurts
– Foetus cannot be palpated
– Receding head on vaginal examination, fluid wave
– Foetal heartbeat muffled

Management

– Monitor.
– Look for diabetes and treat if found.
– Examine the newborn for malformation.
– Risk of neonatal hypoglycaemia: Chapter 10, Section 10.3.4.

Notes:
In acute and chronic polyhydramnios:
– Do not puncture or drain amniotic fluid during pregnancy: risk of infection.
– Use of oxytocin during labour is dangerous and oxytocin should be administered with caution as the over-distended uterus may rupture.
– Amniotomy carries risk of cord prolapse: taking into account gestational age and potential presence of foetal malformation, a caesarean section may be considered. In the event of acute polyhydramnios in the second trimester, vaginal delivery should be pursued.
– Risk of post-partum haemorrhage (insert routinely an IV line).