Oligohydramnios/Polyhydramnios

Question 1

Define oligohydramnios

Answer 1

Low level of amniotic fluid during pregnancy

• Below the 5th centile

Question 2

What are the main causes of oligohydramnios?

Answer 2

• Preterm prelabour rupture of membranes
• Placental insufficiency – resulting in the blood flow being redistributed to the fetal brain rather than the abdomen and kidneys. This causes poor urine output.
• Renal agenesis (known as Potter’s syndrome)
• Non-functioning fetal kidneys, e.g. bilateral multicystic dysplastic kidneys
• Obstructive uropathy
• Genetic/chromosomal anomalies
• Viral infections (although may also cause polyhydramnios)

Question 3

How is oligohydramnios diagnosed?

Answer 3

USS

Amniotic fluid index (AFI) = measuring maximum cord-free vertical pocket of fluid in four quadrants of the uterus and adding them together

Maximum pool depth (MPD) = vertical measurement in any area.

Question 4

How should oligohydramnios be clinically assessed?

Answer 4

Hx - leaking fluid, damp

Ex - symphysis fundal height, speculum exam

US - liquor vol, structural abnormalities, renal agenesis, obstructive uropathy, karyotyping

IGFBP-1

Question 5

Outline the management of oligohydramnios

Answer 5

Optimising the gestation of delivery

Ruptured membranes =
- preterm = induction, steroids, Abx

Placental insufficiency = likely to be pre-term

Question 6

Define polyhydramnios

Answer 6

Abnormally large level of amniotic fluid during pregnancy

amniotic fluid index that is above the 95th centile for gestational age

Question 7

List the causes of polyhydramnios

Answer 7

Idiopathic - 50-60%

Any condition that prevents the fetus from swallowing – e.g. oesophageal atresia, CNS abnormalities, muscular dystrophies, congenital diaphragmatic hernia obstructing the oesophagus

Duodenal atresia – ‘double bubble’ sign on ultrasound scan

Anaemia – alloimmune disorders, viral infections

Fetal hydrops

Twin-to-twin transfusion syndrome

Increased lung secretions – cystic adenomatoid malformation of lung

Genetic or chromosomal abnormalities

Maternal diabetes – especially if poorly controlled

Maternal ingestion of lithium – leads to fetal diabetes insipidus

Macrosomia – larger babies produce more urine.

Question 8

How is Polyhydramnios diagnosed?

Answer 8

USS

Amniotic fluid index = measuring maximum cord-free vertical pocket of fluid in four quadrants of the uterus and adding them together

Maximum pool depth = vertical measurement in any area

Question 9

How is polyhydramnios clinically assessed?

Answer 9

Ex - palpate uterus, does it feel tense

USS - liquor vol, fetal size, structural abnormalities, doppler

Maternal glucose tolerance test

Karyotyping

TORCH screen = Toxoplasmosis, Other (Parvovirus), Rubella, Cytomegalovirus, Hepatitis

Question 10

Outline the management for polyhydramnios

Answer 10

None - for majority

Aminoreduction

Indomethacin - reduce fetal urine output

NG tube - ensure there is not a tracheoesophageal fistula or oesophageal atresia