Function of the amniotic fluid

The amniotic fluid, also called amniotic fluid in the technical terminology, is continuously produced during pregnancy by the inner cells of the amniotic sac. It finally flows around the growing embryo and fulfils important tasks in the process. The amniotic fluid is a clear and aqueous liquid.

On the one hand, it contains components of the blood from the mother and, on the other hand, substances and fluid that the embryo releases via the skin, kidneys, lungs and umbilical cord. Important ingredients of the amniotic fluid are the electrolytes sodium and potassium. Furthermore, fat, glucose, lactate, proteins and fetal epithelial cells are important components of the fluid and fulfill a nutritional function of the embryo.

It also contains urea, which comes from the urine of the fetus. About every three hours, the amniotic fluid in the womb is completely replaced and renewed. In addition, from the 5th month of pregnancy, the fetus drinks about 400ml of amniotic fluid daily.

This enormous reduction must be compensated for. The amount absorbed by the child is absorbed in the child’s intestine and reaches the maternal circulation via the placenta. If the kidneys of the embryos are functional, the filtered amount is also excreted again as urine into the amniotic sac. As a rule, the new formation of amniotic fluid and its absorption are in constant equilibrium.

Amniotic fluid diagnostics

Amniotic fluid can also be obtained from the amniotic sac by means of an amniotic fluid puncture, the examination known as amniocentesis. This examination is part of prenatal diagnostics. This means that even before the birth of the child, an examination of the child for possible existing genetic defects takes place.

It is carried out especially when abnormal ultrasound images have raised the suspicion of trisomy 21. During the examination, the doctor pokes through the abdominal wall with a fine but long needle and ultrasound control and under suction removes a few milliliters of amniotic fluid. The scabbed-off epithelial cells of the embryo are of particular diagnostic importance, because they contain the genetic material. In addition, a changed composition of the amniotic fluid can also provide indications of disease or complications during pregnancy. The sex of the unborn child can also be reliably determined by this examination.