Amniotic fluid, amniocentesis

1. Big picture

Amniotic fluid is the fetus’s protective and developmental environment. It allows movement, protects the cord, supports lung development, and reflects fetal swallowing, fetal urine production, placental function, and membrane integrity.

For the exam, think of this topic in two halves:

1. Amniotic fluid physiology and abnormalities

   • normal formation and function
   • oligohydramnios
   • polyhydramnios
   • ultrasound assessment: amniotic fluid index and deepest vertical pocket

2. Amniocentesis

   • diagnostic procedure using amniotic fluid
   • mainly for genetic diagnosis, infection testing, fetal lung maturity in selected contexts, and sometimes therapeutic drainage in severe polyhydramnios

Key oral-exam sentence:

Amniotic fluid volume is a dynamic balance between fetal urine production, fetal swallowing, lung fluid secretion, membrane transfer, and placental function; abnormalities often indicate fetal, placental, maternal, or membrane pathology.

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