In prenatal medicine , oligohydramnios is when the amount of amniotic fluid falls below 200 to 500 ml during pregnancy . In other words, an amniotic fluid index ( AFI ) of less than 5.1 cm or amniotic fluid deposits of less than 2 cm between the fetus , placenta ( placenta ) and uterine wall are called oligohydramnios.
Oligohydramnios occurs in about 0.5 to 4% of all pregnancies. In the last trimester of pregnancy, about 3 to 5% of all pregnancies have a reduced amount of amniotic fluid. The ICD-10 code O41.0 is given when caring for the expectant mother in the presence of oligohydramnios (without rupture of the bladder ).
Signs of oligohydramnios include, in particular, an unusually small uterus with a view to the gestational age (read: pregnancy week ) and the reduction in child movements (due to the limited space available).
In addition, oligohydramnios is often caused by
- a decreased urine production or urine excretion in the growing child, for example in Potter syndrome
- a very severe growth retardation of the baby
- a placental insufficiency (weakness of the power placenta ), for example if a significant excess of the expected delivery date (transmission)
- an inequality of blood distribution through the placenta in monochorionic, diamote multiples, especially in the fetofetal transfusion syndrome
- Other functional disorders of the placenta (e.g. due to high blood pressure or nicotine consumption by the pregnant woman), through which the kidneys of the unborn child are less well supplied with blood and therefore less amniotic fluid can form
Oligohydramnios causes comparatively poor conduction of the ultrasound waves (the less amniotic fluid, the worse the sound conduction) and is considered a sonographic soft marker for:
- general malformations of the urogenital tract , in particular kidney disorders such. B .:
- Neonatal hemochromatosis
- Obstructive uropathy
- Fetofetal transfusion syndrome in twin pregnancies (oligohydramnios in the donor or the smaller twin )
Oligohydramnios that have existed for a long time and that have existed at an early stage can in particular favor the formation of torticollis , clubfoot and the development of pulmonary hypoplasia due to the lack of lung fluid. The underdevelopment of the lungs can lead to significant lung function impairments after birth . With oligohydramnios before the 24th week of pregnancy , the likelihood of pulmonary hypoplasia is about 24 to 40%.
The oligohydramnios sequence describes a series of effects that are initiated by this inadequate production of amniotic fluid during pregnancy and was first described by Edith Potter , an American pathologist and first named in her honor as Potter syndrome or the Potter sequence .
If there are no other causes for the low amount of amniotic fluid, the pregnant woman can often contribute to a quantitative improvement in the amount of amniotic fluid by drinking an adequate amount of water (especially water ) . If the amount of amniotic fluid does not equalize again and damage to the child is to be expected as a result of the oligohydramia, the possibility of amniotic fluid replenishment ( amniotic infusion ) is considered. With this measure, the amniotic fluid space is filled with a sugar-saline solution through a needle or a catheter. The syringe or catheter was previously pushed through the abdominal wall into the amniotic cavity under ultrasound control. If the general condition of the child is poor or deteriorating, or if transmission is the cause of the oligohydramnios, the method of choice is usually delivery . Depending on the week of pregnancy, induction of lung maturation should be carried out beforehand and, depending on the week of pregnancy, delivery can be carried out vaginally or by caesarean section.