Oligohydramnios & Polyhydramnios Flashcards
What primarily contributes to the amniotic fluid contents in the first trimester?
Maternal plasma and transudation across the amniotic membrane.
What primarily contributes to the amniotic fluid contents in the second trimester?
Fetal urine.
What are the vital functions of amniotic fluid?
- Protecting the fetus from pressure/trauma
- Allowing limb movements
- Supporting normal postural development
- Permitting fetal lung expansion and development.
How is the Amniotic Fluid Index (AFI) calculated?
Adding the deepest vertical pools in centimeters from four quadrants of the abdomen via ultrasound.
What is oligohydramnios?
Too little amniotic fluid, where the AFI is < 5th centile for gestation (AFI < 5cm).
What is anhydramnios?
The near absence of amniotic fluid.
What are the causes of oligohydramnios related to reduced fluid production?
- Renal agenesis
- Multicystic kidneys
- Urinary tract abnormality/obstruction
- Fetal growth retardation (FGR) and placental insufficiency
What is a common cause of oligohydramnios due to fluid leakage?
Preterm premature rupture of membranes (PPROM).
How is oligohydramnios diagnosed?
- By ultrasound showing AFI < 5th centile for gestation
and
- Identifying potential causes like:
- Polycystic kidneys: Enlarged kidneys with multiple cysts, non-visible bladder.
- Renal agenesis: No renal tissue or bladder image.
- Urinary tract obstruction: Urinary tract dilation.
- FGR and placental insufficiency: Small-for-gestational-age baby with abnormal Doppler.
When is oligohydramnios considered severe early onset?
< 24 weeks
What are the complications of severe early-onset oligohydramnios?
Pulmonary hypoplasia and limb deformities
What is the prognosis for renal agenesis or bilateral cystic kidneys?
Lethal prognosis.
How severe is oligohydramnios caused by FGR/uteroplacental insufficiency?
Less severe, less commonly leads to limb or lung problems.
What is polyhydramnios?
Excessive amniotic fluid, defined as an AFI > 95th centile for gestation (AFI > 25 cm).
How is polyhydramnios diagnosed clinically?
- Severe abdominal distension with discomfort.
- Uterus larger than date (increased SFH).
- Tense and tender abdomen on palpation, with difficulty palpating fetal poles.
What are the maternal causes of polyhydramnios?
- Diabetes mellitus
- Syphilis
- Placental tumors (e.g., chorioangioma)
- Arteriovenous fistula
What are the fetal causes of polyhydramnios?
- Multiple pregnancy
- Esophageal atresia
- Duodenal atresia
- Anencephaly
What is Idiopathic polyhydramnios?
Polyhydramnios when no specific cause is identified.
What are the complications of polyhydramnios?
- Preterm labor
- Cord prolapse after membrane rupture
How is maternal discomfort relieved in severe polyhydramnios?
Amnioreduction.
What is the management of polyhydramnios due to maternal diabetes?
Prompt maternal glycemic control.
What is the purpose of amnioreduction in severe polyhydramnios?
- Relieve abdominal distension.
- Minimize the risk of preterm labor.
