Lecture of poly amniotic fluid (plenty of amniotic fluid)

2021-03-21 12:00 AM

Normally, the amount of amniotic fluid is about 300 to 800ml, from 800 to 1500ml, it is called amniotic fluid, poly amniotic fluid when the amount of amniotic fluid exceeds 2000ml.

Physiological function of amniotic fluid

An amniotic sac is made around day 12 after the egg is fertilized. In the first trimester of pregnancy, amniotic fluid is isotonic and similar to maternal plasma. During the second and second half of pregnancy the amniotic fluid becomes hypotonic.

The volume of amniotic fluid increases gradually through the beginning of the third trimester of pregnancy and from there is constant until full term. During the 37-to-41-week period, the volume of amniotic fluid is reduced by 10%. From the 42nd week onwards, the volume of amniotic fluid decreases very rapidly, about 33% in one week.

Amniotic fluid plays the role of:

Protect the fetus from direct injury to the uterus.

Regulate body temperature for the fetus.

Allow the fetus to move freely in the uterus.

Exchange of water, electrolytes, between fetus and mother.

Help the fetal's rectification.

During labor, the amniotic fluid helps to erase the cervix.

Amniotic fluid changes mainly depending on the secretion of amniotic fluid, the permeability of the vessel wall and urine of the fetus. Within an hour about 350 - 375 ml of amniotic fluid is changed.


Poly amniotic fluid is generally caused by overproduction of amniotic fluid or a disorder of the reabsorption of amniotic fluid. There are maternal, fetal and placenta causes.

Cause on the mother's side

Diabetes before or during pregnancy is a common cause.

Anti-Rh antibodies and secondary hemolytic diseases due to abnormal antibodies can cause severe fetal anemia or fetal edema associated with poly amniotic fluid.

Dystrophy increases muscle tone (rare).

Causes of the placenta

Membranomas can cause heart failure in the fetus and lead to poly amniotic fluid.

Pathologies of the endometrium or damage to the pancakes (syphilis)

Causes of pregnancy

 Impairment of fetal central nervous system (intracranial, neural tube defect).

Gastrointestinal system structural defect (obstruction of the esophagus or gastrointestinal tract).

Fetal chromosomal abnormality.

Non-immune-factor pregnancy: has a very poor prognosis and is often associated with poly amniotic fluid. The typical case has placenta edema.

Twin-amniotic transfusion syndrome: is a disorder with a poor prognosis, occurring at a rate of 15% in a single-membrane, two-amniotic twin pregnancy, a complication of poly amniotic fluid in the fetus receiving blood.


Normally, the amount of amniotic fluid is about 300 - 800ml, from 800-1500ml, it is called amniotic fluid. Poly amniotic fluid when the amount of amniotic fluid exceeds 2000ml (this figure is of little significance because in clinical practice it is not possible to accurately estimate the amount of amniotic fluid. amniotic fluid volume). 

The rate of poly amniotic fluid is about 0.2 - 1.6%.

The amniotic fluid index (AFI) is often used by ultrasound to determine poly amniotic fluid. Called poly amniotic fluid when the amniotic fluid index (AFI) exceeds 25 cm (measured using Phelan's technique) this method should be preferred in twins.

Clinical forms

Clinically we can have 2 forms, that is poly amniotic fluid and chronic poly amniotic fluid, poly amniotic fluid is less common.

Acute poly amniotic fluid:

Acute polyhydramnios usually occurs in the 16-20 weeks of pregnancy, often inducing labor before 28 weeks or because symptoms are so severe that pregnancy is suspended.

The symptoms are mainly caused by the rapidly growing amniotic fluid, causing the uterus to become enlarged and fast, and press on the diaphragm, making it difficult to breathe. The clinical picture depends on the degree of poly amniotic fluid and how rapidly the onset of disease is:

The abdomen grows rapidly and tightens.

The uterus is tight and painful.

Unable to touch parts of the fetus, careful examination may show signs of floating lumps.

The fetal heart is difficult to hear or hear from afar.

Vaginal examination shows that the lower part is swollen, the cervix is ‚Äč‚Äčopened, the amniotic head is stretched

Varicose and varicose veins, especially lower extremities, due to compression of the lower aorta.

Maternal dyspnea and subsequent respiratory failure may occur.

Fetal structural malformations should be eliminated by ultrasound in this situation as acute poly amniotic fluid may be accompanied by fetal malformations such as obstruction of the esophagus or high segment of the gastrointestinal tract, an infarction, or fissure spina bifida ...

Chronic poly amniotic fluid:

Chronic poly amniotic fluid accounts for 95% of poly amniotic fluid and usually occurs in the last months of pregnancy. The disease progresses slowly, so the patient is more likely to adapt to the symptoms. The patient does not have much pain and does not have as much difficulty breathing as in acute poly amniotic fluid.

Women come to the examination in the last three months because they feel heavy, stomach tight, have difficulty breathing, and heart palpitations Symptoms usually develop slowly. Amniotic fluid increases gradually to a large amount, making the uterus stretch, making it difficult to breathe and tired.

Physical examination:

The uterus is larger for gestational age.

There are signs of waves.

Poles of the fetus are difficult to palpate and signs of a floating lump.

Vaginal examination finds the lower segment bulging.


Ultrasound: Ultrasound not only has a role to help confirm diagnosis, but also helps in early detection of fetal abnormalities and appendages.

Amniotic fluid test: quantification of a Feto - protein, Acetylcholinesterase, iron contamination to detect neural tube defects.  

Other general tests to find possible maternal diseases such as syphilis, diabetes, toxoplasmosis, blood type and antibody screening ...

Differential diagnosis

Pregnancy: seen in the early stages of pregnancy, the abdomen often grows faster than the gestational age, spontaneously spontaneous vaginal bleeding, a little. Quantitative detection of serum bhCG is very high, ultrasound shows images of falling snow or bunches of grapes, bread crumbs.

Twins: the abdomen is enlarged and fast during pregnancy, having a lot of pregnancy, the fetus in many places, finding many poles, many limbs ... Diagnosis is accurately eliminated through ultrasound.

Abdomen: no signs of pregnancy, sign of waves crashing, knocking cloudy in the low area, abdomen flat, collateral circulation Separate diagnosis by ultrasound.

Ovarian tumor: Patients often show no signs of pregnancy and symptoms of morning, stomach usually get bigger, sometimes feeling severe or painful in case of complications. differential diagnosis.

Urinary retention: the patient feels tightness and develops a rapidly growing abdomen that was not previously present. When in doubt should urinate


Resting, taking diuretics, limiting water, and salt intake are less effective and should not be encouraged.

Acute poly amniotic fluid

Amniocentesis: relieves maternal respiratory symptoms. This is only temporary therapy.

Suspension of pregnancy by inducing labor: If the fetus has a structural or chromosomal abnormality, the healthcare provider should advise the couple on the prognosis and several solutions to choose from, including termination of pregnancy.

Chronic poly amniotic fluid

In mild cases, there is no need for intervention, but waiting for the full-term fetus if there are no other obstetric indications.

If the patient develops difficulty breathing, has abdominal pain, or has difficulty walking, he / she is admitted to the hospital.

Medical treatment: Recently, Indomethacin is used to treat poly amniotic fluid. This drug works to reduce the amount of amniotic fluid secreted or increase the reabsorption of amniotic fluid, reduce the amount of urine excreted by the fetus and increase the exchange of fluid through the fetus. However, Indomethacin causes premature closure of the ductus arteriosus if used for longer than 48-72 hours or used after 32 weeks of pregnancy. There are a number of other known complications of the fetus and infant that have been associated with the use of Indomethacin. Includes: increased incidence of necrotizing enterocolitis in infants, pulmonary hypertension, neonatal renal failure. For the reasons mentioned above, Indomethacin is rarely used in the treatment of poly amniotic fluid and must be used with extreme caution.

Dosage 1.5 - 3 mg / kg / day.

Inducing labor: when the fetus is 38-39 weeks old, or the pregnant woman has difficulty breathing, has difficulty walking.

Amniocentesis at birth: Active amniocentesis reduces uterine tension and helps labor progress smoothly, and at the same time, limits premature peeling and prolapse of umbilical cord. Due to a large amount of fluid, when this volume is suddenly withdrawn, it quickly reduces the pressure and contact area between the placenta and the uterus, which can cause premature peeling and prolapse of the umbilical cord. Therefore, it is important to perform an amniocentesis carefully, using a needle to slowly drain the amniotic fluid. Be prepared for a cesarean section to prevent complications occurring when amniocentesis.

During labor often weak uterine contractions due to the uterus being over-stretched so it is possible to press the amniotic fluid early to reduce the pressure of the amniotic chamber to help the labor progress faster.

When the amniotic rays fix the fetus to prevent the umbilical cord prolapse.

If necessary, uterine contractions can be assisted with oxytocin infusion.

Because the uterus is too tight, there is a risk of postpartum bleeding due to uterine sputum, so a uterotonic must be given immediately after birth.


In general, the perinatal mortality rate increases with the deep level of poly amniotic fluid.

The prognosis is bad even though on ultrasound it does not detect fetal malformations.

The high mortality rate of babies is often due to premature birth with abnormal pregnancy (39%), umbilical cord prolapses, premature removal due to excessive tension in the uterus ...

Common maternal complications are bleeding due to uterine sputum, premature peeling vegetables, an abnormal fetal position that increase the indication of intervention procedures. Maternal respiratory disturbances can range from dyspnea to severe respiratory distress. This condition can be clearly seen in acute poly amniotic fluid.