Oligohydramnios is a pregnancy condition during which there is a deficiency in amniotic fluid. Oligohydramnios is the opposite of polyhydraminos, during which there is excess amniotic fluid. Amniotic fluid is the liquid contained in the mother’s amniotic sac. Amniotic fluid surrounds and protects the fetus. It also aids in the development of fetal limbs, lungs, muscles, and digestive system. Oligohydramnios can cause growth and developmental issues for the fetus.
Causes of Oligohydramnios
Kidney or urinary tract issues are one of the main causes of oligohydramnios. At the beginning of pregnancy, the mother produces water that constitutes most of the amniotic fluid. After roughly 20 weeks gestation, urine from the fetus becomes the primary element. An inability to produce adequate amounts of urine can contribute to oligohydramnios. Postdate pregnancy can also cause oligohydramnios. Amniotic fluid can decrease if a term exceeds 42 weeks.
Oligohydramnios can also be caused by:
- Maternal dehydration
- Urinary tract abnormalities
- Membrane leaking or rupture
- Genitourinary obstruction
- Fetal polycystic or multicystic kidneys
- Uteroplacental insufficiency from maternal hypertension
- Bilateral renal agenesis, or failure of both kidneys to develop
- Atresia of the urethra, or an abnormally closed or absent urethra
- Potter’s syndrome, or congenital decreased kidney size
Failure to Diagnose Oligohydramnios
Oligohydramnios should be immediately investigated if a patient shows certain clinical signs. Usually, oligohydramnioscan be treated without serious complications if the mother and fetus are monitored closely. However, life-threatening complications can occur when a doctor or other medical professional fails to diagnose and properly treat the symptoms of oligohydramnios. A common symptom is an abnormally small uterine or abdominal size in comparison to the gestational age and mother’s weight gain.
Clinical signs for oligohydramnioscan include:
- Visibly decreased fluid on ultrasound
- Uterine contractions
- Abdominal discomfort
Complications of Oligohydramnios
Complications caused by oligohydramnios can include:
- Umbilical cord compression
- Fetal organ compression
- Cesarean delivery
- Intrauterine growth restriction
- Increased risk of miscarriage or stillbirth
- Pulmonary hypoplasia, or incomplete lung development in the fetus
- Musculoskeletal abnormalities such as clubfoot or facial distortion
Diagnosis and Treatment
There are different tests used to measure amniotic fluid levels and oligohydramnios during pregnancy. Amniotic fluid index (AFI) is a common method for amniotic fluid measurement. If less than five centimeters of fluid is detected, oligohydramnios is typically suspected. Deep pocket measurements are also used to measure amniotic fluid. The absence of a two-to-three-centimeter fluid pocket can also indicate oligohydramnios.
Treatment for oligohydramnios depends on the gestational age of the fetus. Non-stress tests and contraction tests may be used to monitor the monitor if the pregnancy has not reached full term. During delivery, amino-infusion is a common oligohydramnios treatment. During amino-infusion, an intrauterine catheter is used to add fluid around the umbilical cord. Amniocentesis is also used to inject fluid into the amniotic sac. If the mother is dehydrated, IV or oral fluids can be used for rehydration. This has improved oligohydramnios conditions.