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It consists of an excessive accumulation of amniotic fluid within the uterine cavity. It is accepted that a volume greater than 2,000 ml of amniotic fluid, in the absence of multiple gestation, should be considered as a polyhydramnios . However, it may not be clinically significant until there is a volume greater than 3,000 ml.

It is observed that this disease appears in approximately 0.5-1% of pregnancies.

Causes of polyhydramnios

The exact causes of polyhydramnios are not known.

However, there are a series of fetal abnormalities that are more frequently associated with this disease, appearing in up to 50% of polyhydramnios cases:

  • Abnormalities that cancel or decrease the fetal swallowing of amniotic fluid: esophageal and duoenal atresia, etc.
  • Central nervous system , chest and abdomen abnormalities .
  • Pulmonary hypoplasia.

Another mechanism implicated in polyhydramnios is the elevation of arterial or venous capillary pressure in the fetoplacental blood circulation. This occurs in pathologies such as:

  • Coriangioma (vascular tumor of the placenta).
  • Obstructive lesions of the large fetal abdominal or thoracic blood vessels.
  • The fetofetal transfusion syndrome observed in monozygotic twin gestations.

An increased incidence of polyhydramnios has also been seen in pregnancies of diabetic mothers.

Under normal conditions, the volume of amniotic fluid at any time during pregnancy is the result of the balance between its production and reabsorption. In polyhydramnios, it seems that neither the production nor the reabsorption of the amniotic fluid is altered, but it does seem that there is an alteration in its transport.

Causes of polyhydramnios

The symptoms of polyhydramnios are caused mainly by the mechanical repercussion of excess fluid within the uterine cavity. The increase in uterine volume and the compression of neighboring organs have a special impact on the respiratory dynamics and the return blood circulation to the heart by compression of the great abdominal venous vessels.

Two clinical forms are distinguished, according to the speed of establishment of excess fluid:

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Rapid onset (acute polyhydramnios): This form usually appears earlier in the course of pregnancy, usually around the second trimester of pregnancy. The most frequent symptoms are:

  1. The pain.
  2. Respiratory difficulty.
  3. Preterm delivery before week 28 is common.

It evolves rapidly, so that the pain becomes unbearable and the woman is unable to lie down.

Slow onset: the symptoms are less striking and better tolerated by the woman, and they do not usually appear before the third trimester of pregnancy. Respiratory distress initially appears when lying down, and edema of the extremities and vomiting are common.

How is it diagnosed?

The diagnosis of polyhydramnios is based on the clinical and ultrasound study.

Clinical study

The presence of increased uterine volume, the inability to palpate fetal parts, and compressive symptoms are highly suggestive, all due to excess fluid in the uterine cavity.

Ultrasound study

Ultrasound plays a very important role in the diagnosis, since it allows the early diagnosis of polyhydramnios (from the 16th week of pregnancy), as well as the diagnosis of possible associated fetal anomalies and the ruling out other alterations that may simulate an excess of amniotic fluid.

How is it treated?

The treatment is based on rest, sedation and evacuation of the liquid periodically, by means of an evacuating amniocentesis .

The woman should be hospitalized as soon as the first symptoms appear and the amniocentesis can be repeated as many times as necessary to keep her free of symptoms.

How can I avoid it?

Because the cause of polyhydramnios is not exactly known, the only thing that can be done to avoid it is to take good control of the pregnancy, especially if any of the factors that favor its appearance are present.

Every pregnant woman should see her gynecologist if she has abdominal pain and respiratory distress, which are the typical symptoms of polyhydramnios, so that it can be evaluated by the doctor and he can carry out the necessary tests for diagnosis.


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Hello Readers, I am Nikki Bella a Psychology student. I have always been concerned about human behavior and the mental processes that lead us to act and think the way we do. My collaboration as an editor in the psychology area of ​​Well Being Pole has allowed me to investigate further and expand my knowledge in the field of mental health; I have also acquired great knowledge about physical health and well-being, two fundamental bases that are directly related and are part of all mental health.

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