Amniotic fluid protects the fetus during pregnancy and protects the mother. The examination of amniotic fluid osmotic pressure can reflect the growth and maturity of the fetus in the uterus. After the second trimester, the fetal urine is discharged into the amniotic cavity, and the osmotic pressure of the amniotic fluid is gradually reduced. Lowering the osmotic pressure of amniotic fluid suggests that the fetus gradually matures.

Basic Information

Specialist classification: maternity check check classification: biochemical examination

Applicable gender: whether women are fasting: not fasting

Tips: Amniocentesis is usually performed in the second trimester (16-21 weeks of gestation). Normal value

Early pregnancy is equivalent to blood permeation (pressure).

Full-term pregnancy 230 ~ 270mmol / L (230 ~ 270mOsm / L).

Clinical significance

≤270mmol/L fetal maturity.

Precautions

Amniocentesis is usually performed in the second trimester (16-21 weeks of gestation). The urine should be drained before surgery, with both hands on the hips and gently turn the waist and abdomen. Then supine, use B-ultrasound to detect the positioning, select the puncture point, and puncture under strict aseptic operation conditions. Generally, about 20 ml of amniotic fluid is taken and placed in a clean and sterilized centrifuge tube for immediate inspection.

Inspection process

Amniotic fluid specimen collection: empty urine before surgery, with both hands on the hips, gently turn the waist and abdomen. Then supine, use B-ultrasound to detect the positioning, select the puncture point, and puncture under strict aseptic operation conditions. Generally, about 20 ml of amniotic fluid is taken and placed in a clean and sterilized centrifuge tube for immediate inspection. The detection method is the same as the physical examination method.

Not suitable for the crowd

Amniocentesis is an invasive examination, puncture should be carefully decided, and full understanding and consent of pregnant women and their families are required before surgery.

1, generally in the second trimester (pregnancy 16-21 weeks). Early pregnancy, late stage should not be checked.

2, no puncture appropriate symptoms should not be carried out.

If there are no other special reasons, one of the following indications must be available:

1. When there is indication for induction of labor in high-risk pregnancies, the maturity of the fetus can be understood, combined with the measurement of placental function, and the time of induction of labor is determined to reduce the perinatal mortality.

2. There have been many unexplained abortions, premature birth or stillbirth history, suspected of having a hereditary disease in the fetus; those who have been married to chromosomal abnormalities; one or both of the couples have chromosomal abnormalities or parents with metabolic defects.

3.35-40 years old pregnant women, talking about fetal chromosomal abnormalities.

4. Necessary fetal gender diagnosis.

5. Have had a serious viral infection in early pregnancy or have been exposed to large doses of ionizing radiation.

6. The maternal fetal blood type is inconsistent and judge the prognosis of the fetus.

7. If there is a suspected premature rupture of membranes, the PH and smear of the vaginal fluid can be used to check whether the amniotic fluid forms crystals and fat cells to determine whether it is amniotic fluid.

Adverse reactions and risks

complication:

1, maternal injury: puncture needle stab wound blood vessels caused by abdominal wall hematoma uterine subserosal hematoma. Occasionally, amniotic fluid enters the maternal blood circulation from the puncture hole and causes amniotic fluid embolism. The bladder was not emptied before the puncture, and the bladder was injured.

2, damage to the fetus, placenta and umbilical cord: puncture needle damage to the fetus can occur bleeding, stab wounds and umbilical cord can also occur bleeding or hematoma. Therefore, the source of bleeding should be identified when taking hemorrhagic amniotic fluid. If you suspect that you are from a fetus, you should continue to listen to the fetal heart.

3, amniotic fluid leakage: postoperative amniotic fluid leakage from the needle hole, resulting in too little amniotic fluid, affecting fetal development, and even cause miscarriage or premature birth.

4, abortion or premature delivery: the incidence of abortion or premature birth 0.1% -0.2%, often occurred within one week after surgery, even after the puncture, premature rupture of membranes leading to premature delivery.

5, intrauterine infection: postpartum may have maternal fever. Intrauterine infection can cause abnormal fetal development, or even fetal death. Therefore, amniocentesis should be strictly aseptic.