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
What maternal condition increases risk of polyhydramnios and why
Diabetes - leads to macrosomia. Larger babies will produce more urine
What can maternal use of lithium during pregnancy cause in a foetus
Foetal diabetes insipidus
What can foetal diabetes inspidus lead to
Polyhydramnios
How will uterus feel in polyhydramnios
Tense
What test should mothers have if polyhydramnios found
OGTT
How is polyhydramnios detected
US - amniotic fluid index
How is polyhydramnios usually managed
No intervention required
If mother is breathless, how is polyhydramnios managed
Amnioreduction or Indomethacin is given
What timeframe should indomethacin not be used from and why
> 32W as indomethacin will cause pre-mature closure of ductus arteriosus
If a baby has had known polyhydramnios of unknown aetiology what is done when it is born
NG tube must be passed prior to feeding to exclude oesophageal atresia or tracheo-oeseophageal fistula
What are 3 complications of polyhydramnios and why
- Cord prolapse - increase room
- Malpresentation
- PPH
