Antenatal: Oligohydramnios and Polyhydramnios Flashcards
Define oligohydramnios
Amniotic fluid index below the 5th centile
What is oligohydramnios
Lack of amniotic fluid
What are 5 causes of oligohydramnios
PPROM Placental insufficiency Potter's syndrome Obstructive uropathy Chromosomal anomalies
Why does placental insufficiency cause oligohydramnios
Foetus preferentially diverts blood flow to it’s brain, opposed to the kidneys
What is potter’s syndrome
Renal agenisis
What imaging is ordered for oligohydramnios
US
What test is performed to check for oligohydramnios
IGFBP-1
What does the presence of insulin-like growth factor binding protein 1 indicate
Membranes have ruptured
When does amniotic fluid volume increase until
33W, then it plataus
What is amniotic fluid made of
- Urine output
- Respiratory secretions
- Placental fluid
Explain processing of amniotic fluid
Foetus breathes and swallows amniotic fluid.
Kidneys then covert this to urine which is stored in the bladder and released
What can cause oligohydramnios in terms of pathophysiology
Anything that decreases kidney’s formation of urine our obstructs excretion leads to oligohydramnios.
How is olgiohydramnios investigated
US
What is used to assess amount of amniotic fluid
Amniotic fluid index
What are the two main causes of oligohydramnios
PPROM
Placental insufficiency
If oligohydamnios is due to rupture of membranes when does labour usually occur
24-48h after
If PPROM and labour does not start what should be considered
IOL at 34-36W to prevent infection.
Give antibiotics and glucocorticoids
If due to placental insufficiency when should delivery be aimed for depending on growth, doppler and CTG
37W
Why does oligohydramnios carry a poor prognosis in second term
Due to premature delivery and causing pulmonary hypoplasia
What are 2 complications of oligohydramnios
Pulmonary Hypoplasia
- Less fluid restricts ability foetus can move it’s limbs which can lead to severe contractures post-delivery
Define polyhydramnios
Amniotic fluid index >95th centile for gestational age
What is the main cause of polyhydramnios
Idiopathic (60%)
What 3 conditions preventing swallowing can lead to polyhydramnios
Congenital diaphragmatic hernia
Oesophageal atresia
CNS Disorders
What GI condition can cause polyhydramnios
Duodenal atresia
