Polyhydramnios and Oligohydramnios Clinical Presentation

Updated: Sep 20, 2017
  • Author: Brian S Carter, MD, FAAP; Chief Editor: Dharmendra J Nimavat, MD, FAAP  more...
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Presentation

Physical Examination

Amniotic fluid

The volume of the amniotic fluid is evaluated by visually dividing the mother's abdomen into four quadrants. The largest vertical pocket of fluid is measured in centimeters. The total volume is calculated by multiplying this value by 4.

Polyhydramnios is usually defined as an amniotic fluid index (AFI) of more than 24 cm or a single pocket of fluid at least 8 cm in depth that results in an amniotic fluid volume of more than 2000 mL. [14]

Oligohydramnios is ultrasonographically defined as an AFI less than 7 cm or the absence of a fluid pocket 2-3 cm in depth.

Polyhydramnios

Visual inspection may reveal a rapidly enlarging uterus in the pregnant mother. Multiple gestations are associated with polyhydramnios. 

Fetal abnormalities associated with polyhydramnios include neonatal macrosomia, fetal or neonatal hydrops with anasarca, ascitespleural or pericardial effusions, and gastrointestinal tract obstruction (eg, duodenal atresia, tracheoesophageal fistula).

Skeletal malformations can also occur, including congenital hip dislocation, clubfoot, and limb reduction defect.

Abnormalities in fetal movement are suggestive of primary neurologic abnormalities or may be in association with a genetic syndrome, such as polyploidy.

Oligohydramnios

When the oligohydramnios is associated with renal agenesis or dysgenesis, symptoms/signs include a marked deformation of the fetus due to of intrauterine constraint (Potter syndrome). Obstructive uropathies cause similar deformations, including external compression with a flattened facies and epicanthal folds, hypertelorism, low-set ears, a mongoloid slant of the palpebral fissure, a crease below the lower lip, and micrognathia. Thoracic compression may also occur.

Oligohydramnios adversely affects fetal lung development, resulting in pulmonary hypoplasia that typically leads to death from severe respiratory insufficiency. Other fetal deformations include bowed legs, clubbed feet, a single umbilical artery, gastrointestinal atresias, and a narrow chest secondary to external compression. Infants are typically small for their stated gestational age (SGA). [15]  When an abdominal mass is found on examination of the infant in this clinical setting, it often represents multicystic-dysplastic kidney, enlarged urinary bladder, or prune-belly syndrome.