Polyhydramnios

Question 1

What is polyhydramnios?

Answer 1

Increased amniotic fluid

Question 2

Student report: I had to examine a woman who was large for dates. I was asked about the causes

Answer 2

Large for dates:
Wrong dates
Big baby - macrosomia: genetic, diabetes
Polyhydramnios 
Big baby and polyhydramnios e.g. diabetes

Question 3

How is polyhydramnios detected?

Answer 3

• Increased symphysiofundal height (not very useful on its own)
• Tense cystic uterus; foetal parts hard to feel
• Amniotic fluid index (AFI)
• Ultrasound 4 quadrants: for each, measure depth of deepest unobstructed pool; sum of 4 measurements
• Total of 8-18cm is normal; >24cm is polyhydramnios
  or single pool of more than 8cm

Question 4

“Deepest vertical pool” detected on ultrasound

Answer 4

> 8cm = PH

Question 5

What causes polyhydramnios?

Answer 5

Idiopathic 60% of time
Maternal problem 20% e.g. diabetes, infection with parvovirus or CMV
Foetal abnormality in 20%

Question 6

Polyhydramnios mechanisms:

Answer 6

Foetal swallowing difficulties prevents fluid uptake by foetus –> fluid builds up in amniotic sac
Swallowing problems: anencephaly/ upper GI atresia
Polyuria: maternal diabetes –> glucose crosses placenta –> foetal hyperglycaemia –> polyuria
Heart failure due to septal defect: VSD, Down’s syndrome
Cardiac malformations
Foetal hydrops
Anaemia/ heart failure: rhesus immunisation, parvovirus
Twin-twin transfusion syndrome (heart failure of recipient twin)

Question 7

Mnemonic for causes:

Answer 7

DITCH

Diabetes
Idiopathic
Twins
Congenital abnormality
Heart failure

Question 8

Risks of polyhydramnios

Answer 8

6Ps
Placental abruption
Pretty unusual lie
Premature labour
Prolapse of cord 
Post partum haemorrhage
Perinatal mortality