What is the Difference Between Polyhydramnios and Oligohydramnios?

Polyhydramnios and oligohydramnios are conditions that occur during pregnancy, involving abnormal levels of amniotic fluid. The main differences between the two are:

Polyhydramnios is a pathological increase in amniotic fluid volume, with values above 8 cm indicating this condition. It occurs in 1% of pregnancies and is associated with complications such as maternal dyspnea, preterm labor, premature rupture of membranes, abnormal fetal presentation, umbilical cord prolapse, postpartum hemorrhage, fetal macrosomia, hypertensive disorders of pregnancy, and urinary tract infections. Some common causes of polyhydramnios include gestational diabetes, fetal anomalies, fetal infections, and Rh incompatibility.
Oligohydramnios is a condition where there is too little amniotic fluid around the fetus, with values below 2 cm indicating this condition. It occurs in about 11% of pregnancies and can lead to complications such as fetal lung development issues, pulmonary hypoplasia, bowed legs, clubbed feet, a single umbilical artery, gastrointestinal atresias, and a narrow chest secondary to external compression. Oligohydramnios can be caused by factors such as renal agenesis or dysgenesis, and obstructive uropathies.

Both conditions can be diagnosed through ultrasound. The amniotic fluid index (AFI) is used to measure the amount of amniotic fluid, with a normal range being between 5 and 25 cm. In cases of multiple gestation, a range of 3–8 cm is defined as normal.

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What is the Difference Between Polyhydramnios and Oligohydramnios?

Comparative Table: Polyhydramnios vs Oligohydramnios

Here is a table comparing the differences between polyhydramnios and oligohydramnios:

Condition	Definition	Incidence	Causes	Complications
Polyhydramnios	Excessive production of amniotic fluid during pregnancy	1 to 2% of pregnancies	Rh incompatibility, fetal anemia, maternal diabetes, genetic conditions, multiple gestations	Cord prolapse, placental abruption, premature birth, perinatal death
Oligohydramnios	Inadequate amount of amniotic fluid during pregnancy	4% of pregnancies	Fetal urine output, leakage of amniotic fluid from the uterus, fetal kidney issues, gastrointestinal malformations, fetal neurological problems, mechanical obstruction of the esophagus	Complications in fetus growth, increased pressure on the uterus, increased risk of cesarean section

Both polyhydramnios and oligohydramnios are pregnancy-related complications related to the volume of amniotic fluid. Polyhydramnios is characterized by an excessive amount of amniotic fluid, while oligohydramnios is characterized by an inadequate amount of amniotic fluid. These conditions can cause complications for both the mother and the baby, and they require proper diagnosis and treatment.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.