Causes of oligohydramnios
What are the reasons for oligohydramnios? There are 4 main reasons:
1, overdue pregnancy, placental dysfunction, insufficient perfusion, fetal dehydration, resulting in less amniotic fluid. Some scholars believe that when the fetus is overmature, its renal tubules are more sensitive to antidiuretic hormones, less urine leads to oligohydramnios. The incidence of oligohydramnios caused by prolonged pregnancy is 20% – 30%.
2. Fetal malformations, such as congenital kidney deficiency, renal dysplasia, ureteral or urethral stricture and other malformations caused by less or no urine and caused oligohydramnios.
3. Fetal intrauterine growth retardation (IUGR) oligohydramnios is one of the characteristics of fetal intrauterine growth retardation. Chronic hypoxia leads to the redistribution of fetal blood circulation, which mainly supplies the brain and heart, while renal blood flow decreases, and fetal urine production decreases, resulting in oligohydramnios.
4. Amniotic membrane lesions, electron microscopic observation found that amniotic membrane epithelium in oligohydramnios thinning, epithelial cells atrophy, microvilli short and thick, swelling of the tip, a small number of squamous epithelial metaplasia, the cells of rough endothelial reticulum and Golgi complex also decreased, and between epithelial cells and basement membrane desmosomes and half desmosomes decreased. It is considered that some oligohydramnios with unknown reasons may be related to the pathological changes of amniotic membrane.
What are the symptoms of oligohydramnios?
Pregnant women often feel pain because of fetal movement, abdominal circumference and uterine fundus height are less than the month of pregnancy, fetal activity is limited, natural rotation is not easy, so the buttocks appear more often. Prolonged pregnancy usually exceeds 2~3 weeks. Primary uterine inertia or inconsistent uterine contractions often occur during childbirth. The dilatation of the uterine orifice is slow and the first stage of labor is prone to be prolonged. Amniotic fluid is very small, sticky and more yellow green, resulting in fetal hypoxia. Due to lack of amniotic fluid, there are various developmental malformations. If oligohydramnios occurs in early pregnancy, part of the fetal body surface can adhere to amniotic membrane, or the formation of amniotic membrane band to break off the fingers or limbs. If oligohydramnios occurs late in pregnancy, the fetal skin is dry, like parchment.
Because of the lack of amniotic fluid, the fetus is in a mandatory position in the uterus, which is easy to be oppressed and causes special musculoskeletal deformities, such as hand and foot deformities, dorsiflexion, torticollis, upper and lower limb bending. There are often fetal lung hypoplasia, the reasons may be: 1. Pulmonary developmental defects can not excrete fluid to maintain amniotic fluid volume;
2, due to less amniotic fluid, the uterus compression fetal thorax, affecting chest wall and lung expansion;
3, lack of liquid inhalation of terminal alveoli, obstructing lung development. In normal pregnancy, proper inhalation of amniotic fluid is very important for fetal lung expansion and development. More oligohydramnios occurred in early and mid pregnancy due to aborted fetuses.
The effect of oligohydramnios on fetus
All pregnant women know that amniotic fluid and placenta are the basis for the survival and growth of the fetus in vivo, and the instability of amniotic fluid or placenta will directly affect the growth of the fetus. With the growth of the fetus, the amniotic fluid and placenta of pregnant women also increase and enlarge, pregnant women with more amniotic fluid is not a normal pregnancy phenomenon, on the contrary, pregnant women with less amniotic fluid is a danger to fetal life abnormal phenomenon. The majority of pregnant women will directly affect the respiration of the fetus in the maternal body.
What to do with less amniotic fluid?
Pregnant women with less amniotic fluid can cause many problems. If there are such problems, we must treat them in time. In the second trimester of pregnancy, if oligohydramnios is found, fetal malformations often occur, which require careful examination (such as umbilical cord blood or amniotic fluid chromosome examination, excluding chromosomal abnormalities). After removing the possibility of fetal malformation, we can closely observe the fetus’s condition in the uterus and the change of amniotic fluid volume.
If it is due to maternal insufficient blood volume or hypoxia caused by oligohydramnios, a large number of drinking water, intravenous infusion and oxygen inhalation can indeed play a role.
For mothers with hypercoagulation, low-molecular-weight heparin can be injected subcutaneously, or intravenous infusion of low-molecular-weight dextran, so that the blood is not so easy to coagulate, blood circulation of the placenta is more smooth, conducive to the formation of amniotic fluid.
If necessary, amniotic cavity perfusion therapy can also be used, that is, under the guidance of B ultrasound puncture needle into the amniotic cavity via abdominal injection of normal saline to improve the condition of oligohydramnios. This method is now recognized and adopted by more and more people, especially for some early unknown causes of oligohydramnios pregnant women, the fetus is immature, amniotic fluid infusion can improve the effect of oligohydramnios on the fetus in a short time, to maintain the normal development of the fetus.
But before these treatments must be carried out comprehensive assessment, treatment must be in hospital, under strict monitoring, to prevent allergic reactions, bleeding tendency, premature delivery, abortion, infection and other adverse reactions.