Metabolites in amniotic fluid include uric acid, urea, and the like. Before 6 months of gestation, the uric acid value in amniotic fluid is similar to that of maternal serum uric acid. By the time of pregnancy, the uric acid value in amniotic fluid is about twice that of maternal serum uric acid. Increased amniotic fluid uric acid represents an increase in urinary discharge and an increase in fetal muscle weight, which is one of the signs of fetal maturity.

Basic Information

Specialist classification: maternity check check classification: biochemical examination

Applicable gender: whether women are fasting: not fasting

Tips: Empty the urine before surgery, hands on the hips, gently turn the waist and abdomen. Normal value

Early pregnancy 0.22 ± 0.06mmol / L (3.72 ± 0.96mg / dl).

Full-term pregnancy 0.58 ± 0.13mmol / L (9.90 ± 2.23mg / dl).

Clinical significance

Increased in the mother suffering from primary gout, diabetes and so on.

High results may be diseases: Pregnancy diabetes, hyperuricemia considerations

Amniocentesis is usually performed in the second trimester (16-21 weeks of gestation). Pregnant women should empty urine before surgery.

Inspection process

Pregnant women with both hands on their 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.

Detection operation:

1. The dry powder reagent is reconstituted by adding a certain amount of distilled water or buffer according to the instructions, and used after 0.5 h of reconstitution.

2. Take 3 test tubes, indicating the measuring tube, standard tube and blank tube.

3. The test tube is filled with 0.1 ml of amniotic fluid, 0.1 ml of uric acid standard solution is added to the standard tube, 0.1 ml of distilled water is added to the blank tube, and 1.5 ml of enzyme reagent is added to each tube.

4. Mix thoroughly, put at room temperature for 20 min, 500 nm wavelength, adjust “0” with blank tube, and read the absorbance of each tube with spectrophotometer colorimetric.

Not suitable for the crowd

1, amniocentesis is generally performed in the second trimester (pregnancy 16-21 weeks), early pregnancy, late are not suitable.

2, amniocentesis is aseptic operation, there is a risk of complications, the consent of pregnant women and their families should be obtained, and those without amniocentesis should not be carried out.

Adverse reactions and risks


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.