Poly and Oligohydramnios

Question 1

What is the definition of polyhydramnios

What is the definition of oligohydramnios

Answer 1

Amniotic fluid index >24cm
Deepest vertical pocket >8cm

Amniotic fluid index <8cm
Deepest vertical pocket <2cm

Question 2

What are the causes of polyhydramnios?

Answer 2

1) Gestational diabetes
2) Congenital abnormalities such as duodenal or oesophageal atresia
3) Congenital infection: Parvovirus, rubella, CMV
4)Multiple gestation: Twin to twin transfusion syndrome
5) Foetal anemia - Fetal hydrops (rhesus isoimmunization)
6_ Idiopathic

Question 3

What are the investigations of polyhydramnios

Answer 3

Oral glucose tolerance test (GDM)
Ultrasound scan for TTTS, foetal anemia (Rhesus), Nuchal translucency (duodenal atresia) -> amniocentesis
Maternal blood group for rhesus
TORCH screening for congenital infection

Question 4

What are the complications of polyhydramnios?

Answer 4

Preterm labour
Unstable lie
Cord prolapse
PPH (Overdistension => atony)
Placental abruption due to sudden SROM

Question 5

What are the causes of oligohydramnios

Answer 5

1) Uteroplacental insufficiency (Pre-eclampsia, APS, maternal thrombophilia)
2) Rupture of membranes
3) Congenital renal anomalies (Potter’s, vesicoureteric reflux, posterior urethral valves)
4) Multiple gestation: TTTS
5) Teratogens affecting fetal kidney (ACE inhibitors)

Question 6

What investigations would you perform for oligohydramnios?

Answer 6

1) Screen for pre-eclampsia, APS, maternal thrombophilia
2) Confirm rupture of membranes (amnisure)
3) Ultrasound scan for fetal anomalies and fetal biometry (AC, HC, femur length, BPD)
4) Genetic testing: NIPT, Amniocentesis

Question 7

What are the complications of oligohydramnios

Answer 7

Intrauterine or neonatal demise
CTG abnormalities and resultant in emergency delivery (you can add in US monitoring of growth, BPP, US doppler, etc…)