Polyhydramnios is a medical condition describing an excess of
amniotic fluid
The amniotic fluid is the protective liquid contained by the amniotic sac of a gravid amniote. This fluid serves as a cushion for the growing fetus, but also serves to facilitate the exchange of nutrients, water, and biochemical products betwee ...
in the
amniotic sac
The amniotic sac, also called the bag of waters or the membranes, is the sac in which the embryo and later fetus develops in amniotes. It is a thin but tough transparent pair of biological membrane, membranes that hold a developing embryo (and l ...
. It is seen in about 1% of pregnancies. It is typically diagnosed when the
amniotic fluid index
Amniotic fluid index (AFI) is a quantitative estimate of amniotic fluid and an indicator of fetal well-being. It is a separate measurement from the biophysical profile.
AFI is the score (expressed in centimetres) given to the amount of amniotic ...
(AFI) is greater than 24 cm.
There are two clinical varieties of polyhydramnios: chronic polyhydramnios where excess amniotic fluid accumulates gradually, and acute polyhydramnios where excess amniotic fluid collects rapidly.
The opposite to polyhydramnios is
oligohydramnios
Oligohydramnios is a medical condition in pregnancy characterized by a deficiency of amniotic fluid, the fluid that surrounds the fetus in the abdomen, in the amniotic sac. The limiting case is anhydramnios, where there is a complete absence of ...
, not enough amniotic fluid.
Presentation
Associated conditions
Fetuses with polyhydramnios are at risk for a number of other problems including
cord prolapse
Cord or CORD may refer to:
Common meanings
* String (structure), String
* Thin rope
* Twine
* Cord (unit) used for measuring wood
* Power cord
* Umbilical cord
Cord or CORD may also refer to:
Places
* Cord, Arkansas
People
* Alex Cord ( ...
,
placental abruption,
premature birth
Preterm birth, also known as premature birth, is the birth of a baby at fewer than 37 weeks gestational age, as opposed to full-term delivery at approximately 40 weeks. Extreme preterm is less than 28 weeks, very early preterm birth is betwee ...
and perinatal death. At delivery the baby should be checked for congenital abnormalities.
Causes

In most cases, the exact cause cannot be identified. A single case may have one or more causes, including intrauterine infection (
TORCH
A torch is a stick with combustible material at one end which can be used as a light source or to set something on fire. Torches have been used throughout history and are still used in processions, symbolic and religious events, and in juggl ...
),
rh-isoimmunisation, or
chorioangioma of the placenta. In a multiple gestation pregnancy, the cause of polyhydramnios usually is
twin-to-twin transfusion syndrome. Maternal causes include
cardiac problems,
kidney
In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organ (anatomy), organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and rig ...
problems, and maternal
diabetes mellitus
Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...
, which causes fetal
hyperglycemia
Hyperglycemia is a condition where unusually high amount of glucose is present in blood. It is defined as blood glucose level exceeding 6.9 mmol/L (125 mg/dL) after fasting for 8 hours or 10 mmol/L (180 mg/dL) 2 hours after eating.
Blood gluc ...
and resulting
polyuria
Polyuria () is excessive or an abnormally large production or Frequent urination, passage of urine (greater than 2.5 L or 3 L over 24 hours in adults). Increased production and passage of urine may also be termed as diuresis. Polyuria often appe ...
(fetal urine is a major source of amniotic fluid).
A recent study distinguishes between mild and severe polyhydramnios and showed that
Apgar score
The Apgar score is a quick way for health professionals to evaluate the health of all newborns at 1 and 5 minutes after birth and in response to resuscitation. It was originally developed in 1952 by an anesthesiologist at Columbia University, ...
of less than 7, perinatal death and structural malformations only occurred in women with severe polyhydramnios.
In another study, all patients with polyhydramnios, that had a sonographically normal fetus, showed no chromosomal anomalies.
These anomalies include:
*
gastrointestinal
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...
abnormalities such as
esophageal atresia and
duodenal atresia (causing inability to swallow amniotic fluid), anencephaly, facial cleft, neck masses, tracheoesophageal fistula, and diaphragmatic hernias. An annular pancreas causing obstruction may also be the cause.
*Bochdalek's hernia, in which the pleuro-peritoneal membranes (especially the left) will fail to develop and seal the pericardio-peritoneal canals. This results in the stomach protrusion up into the thoracic cavity, and the fetus is unable to swallow sufficient amounts of amniotic fluid.
* fetal
renal
In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and right in the retrop ...
disorders that result in increased urine production during pregnancy, such as in antenatal
Bartter syndrome.
Molecular diagnosis is available for these conditions.
*neurological abnormalities such as
anencephaly, which impair the swallowing reflex. Anencephaly is failure of closure of the rostral neuropore (rostral neural tube defect). If the rostral neuropore fails to close there will be no neural mechanism for swallowing.
*chromosomal abnormalities such as
Down syndrome and
Edwards syndrome, which is itself often associated with gastrointestinal abnormalities.
*Skeletal dysplasia, or dwarfism. There is a possibility of the chest cavity not being large enough to house all of the baby's organs causing the trachea and esophagus to be restricted, not allowing the baby to swallow the appropriate amount of amniotic fluid.
*sacrococcygeal
teratoma
A teratoma is a neoplasia, tumor made up of several types of biological tissue, tissue, such as hair, muscle, Human tooth, teeth, or bone. Teratomata typically form in the tailbone (where it is known as a sacrococcygeal teratoma), ovary, or test ...
Diagnosis
There are several pathologic conditions that can predispose a pregnancy to polyhydramnios. These include a maternal history of
diabetes mellitus
Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained hyperglycemia, high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or th ...
,
Rh incompatibility between the fetus and mother, intrauterine infection, and
multiple pregnancies.
During the pregnancy, certain clinical signs may suggest polyhydramnios. In the mother, the physician may observe increased abdominal size out of proportion for her weight gain and gestation age, uterine size that outpaces gestational age, shiny skin with stria (seen mostly in severe polyhydramnios), dyspnea, and chest heaviness. When examining the fetus, faint fetal heart sounds are also an important clinical sign of this condition.
Treatment
Mild asymptomatic polyhydramnios is managed expectantly. A woman with symptomatic polyhydramnios may need hospital admission.
Antacids may be prescribed to relieve heartburn and
nausea
Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat.
Over 30 d ...
.
No data support dietary restriction of salt and fluid.
In some cases,
amnioreduction, also known as therapeutic
amniocentesis
Amniocentesis is a medical procedure used primarily in the prenatal diagnosis of genetic conditions. It has other uses such as in the assessment of infection and fetal lung maturity. Prenatal diagnostic testing, which includes amniocentesis, is ...
, has been used in response to polyhydramnios.
See also
*
Amniotic fluid index
Amniotic fluid index (AFI) is a quantitative estimate of amniotic fluid and an indicator of fetal well-being. It is a separate measurement from the biophysical profile.
AFI is the score (expressed in centimetres) given to the amount of amniotic ...
References
External links
*
{{Pathology of pregnancy, childbirth and the puerperium
Pathology of pregnancy, childbirth and the puerperium