Polyhydramnios

Introduction The amount of amniotic fluid in normal pregnancy increases with the increase of gestational age, and gradually decreases gradually in the last 2 to 4 weeks. The amniotic fluid volume in the full-term pregnancy is about 1000ml (800-1200ml). If the amount of amniotic fluid exceeds 2000ml in any period of pregnancy, it is called For polyhydramnios. Up to 20,000ml. Most pregnant women have a slower increase in amniotic fluid, which is formed in a relatively long period of time, called chronic amniotic fluid; a few pregnant women have a sharp increase in amniotic fluid within a few days, called acute polyhydramnios. The incidence of polyhydramnios is reported in the literature as 0.5% to 1%, and the incidence of pregnancy with diabetes can reach 20%. When the amniotic fluid is too much, the appearance and traits of amniotic fluid are no different from those of normal people.

Cause

Causes of polyhydramnios

At the end of pregnancy, the average amount of amniotic fluid is about 500 to 1000 c.c. If the secretion is excessive due to abnormality, or the absorption is abnormally low, the amniotic fluid gradually or rapidly increases to 2000c.c. or more. This situation is called "amniotic fluid", the reason is divided into two aspects of the fetus and the mother.

Fetal cause

1 The fetus has a head deformity or a spinal cord split, causing the spinal fluid to mix into the amniotic fluid.

2 The fetus has a digestive tract malformation, which reduces the absorption of amniotic fluid.

3 single-oval twins - because the two fetuses share a placenta, it will affect the development of the fetus. Generally developed large fetuses may cause hypertrophy of the heart or kidneys, causing symptoms of excessive amniotic fluid. Conversely, poorly developed small fetuses form a phenomenon of oligohydramnios.

Maternal reasons

1 The mother's heart or kidney is defective, resulting in poor blood circulation.

2 The mother has diabetes, causing the fetus to have more urine.

an examination

Auxiliary inspection

(1) B-mode ultrasonography: The method of measuring the amniotic fluid volume (AFD) by the vertical depth of a single largest amniotic fluid dark area shows that the distance between the fetus and the uterine wall is increased. If it exceeds 7 cm, it can be considered as excessive amniotic fluid (some scholars believe that it exceeds 8cm can diagnose excessive amniotic fluid). If the amniotic fluid index method (AFI) is used, that is, the head height of the pregnant woman is 30°, the umbilical cord and the abdominal white line are used as the marker points, and the abdomen is divided into four parts to determine the maximum amniotic fluid dark areas of each quadrant. The domestic data is >18cm. Too much amniotic fluid. Phelan thinks that >20cm can be diagnosed. The AFI was significantly better than the AFD method. When the amniotic fluid is too much, the fetus only occupies a small part in the uterine cavity, and the limbs are in a free state, floating in the amniotic fluid, and can also find fetal malformations and twins at the same time.

(2) Amniocentesis and fetal angiography: In order to understand whether the fetus has gastrointestinal malformation, 76% of diatrizoate 20-40 ml is injected into the amniotic cavity. After 3 hours, the contrast agent in the amniotic fluid is reduced. A contrast agent appears in the tract. Then 40% iodized oil 20 ~ 40ml (depending on the amount of amniotic fluid) into the amniotic cavity, turned left and right several times, because the fat-soluble contrast agent and fetal fat have a high affinity, half an hour, 1 hour after the injection, The film is taken separately for 24 hours, and the body surface of the fetus including the head, the trunk, the extremities and the external genitalia can be developed. Amniocentesis may cause premature delivery and intrauterine infection, and contrast agents and radiation may cause damage to the fetus and should be used with caution.

(3) Detection of fetal defects in neural tube defects, this type of fetal malformation is easy to merge with polyhydramnios.

In addition to B-mode ultrasound, there are several detection methods:

1. Determination of amniotic fluid and maternal blood alpha-fetoprotein (-FP): In the fetus with open neural tube defect, -FP infiltrates into the amniotic cavity with cerebrospinal fluid. When pregnancy is combined with neural tube defect, amniotic fluid -FP value exceeds the same period. The normal pregnancy average is more than 3 standard deviations. The maternal serum -FP value exceeded the standard deviation of the normal pregnancy by more than 2 standard deviations.

2, maternal estrogen / creatinine (E / C) ratio determination: When the fetus with a neural tube defect, the E / C ratio is lower than the mean of the normal pregnancy compared to the same period of more than 1 standard deviation.

3, amniotic fluid fast adherent cells, amniotic fluid acetylcholinesterase gel disc electrophoresis, amniotic fluid A and anti--FP monoclonal antibody three sandwich solid phase immunoradiometry, can detect neural tube defects, several methods Simultaneous detection can make up for the shortcomings of B-ultrasound and -FP method.

Differential diagnosis

Symptoms of oligohydramnios

Should pay attention to the identification of hydatidiform mole, twin pregnancy, giant children, should also rule out fetal edema and chromosomal abnormalities caused by diabetes, maternal and child blood group incompatibility, usually only when the amount of amniotic fluid exceeds 3000ml.

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