Oligohydramnios

Question 1

Definition

Answer 1

Abnormally low volume of amniotic fluid surrounding fetus

Question 2

Physiology

Answer 2

Amniotic fluid lies within the amniotic membrane
Initially made from water by mom but is gradually replaced by fetal urine
Amount of fluid peaks at 38 weeks and decreases as birth approaches

Question 3

Causes

Answer 3

• Rupture of membranes
• Fetal growth restriction
• Maternal medication co-morbities (e.g. hypertension)
• Placental abnormalities (e.g. abruption)
• Fetal urinary tract anomolies (e.g. renal agenesis, posterior urethral valves)
• Maternal drug use (E.g. NSAIDs, ACE inhibitors)
• Post-term pregnancy

Question 4

Diagnosis

Answer 4

• USS
• Hx of clear or light pink fluid leaking from vag (sterile speculum examination and assess the fluid)
• Examination symphysis fundal height
• for ROM, IGFBP-1 or PAMG in vagina

Question 5

USS signs

Answer 5

• amniotic fluid index <5cm (measuring maximum cord-free vertical pocket of fluid in four quadrants of the uterus and adding them together)
• maximum vertical pocket <2cm (vertical measurement in any area)

Question 6

Treatment

Answer 6

depends on the underlying cause
- ruptured membrane
= if this is preterm and labour doesn’t start automatically → induction of labour
= course of steroids to help lungs
- placental insufficiency = planned delivery