Amniotic fluid is the warm, protective liquid that fills the amniotic sac surrounding a fetus during pregnancy. It plays several vital roles, including cushioning the baby from injury, maintaining a stable temperature, allowing the fetus to move and develop muscles and bones, and helping the lungs and digestive system mature. On ultrasound, amniotic fluid appears as dark, anechoic spaces surrounding the fetus. Sonographers assess the amount of amniotic fluid at every obstetric ultrasound because too much fluid, called polyhydramnios, or too little fluid, called oligohydramnios, can both indicate problems with the pregnancy that require further evaluation.
Sonography Term