Oligohydramnios

Changed by Jeremy Jones ◉ , 20 Sep 2021

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Oligohydramnios refers to a situation where the amniotic fluid volume is less than expected for gestational age. Often these fetuses have <500 mL of amniotic fluid.

Epidemiology

The estimated prevalence can be up to ~6% of pregnancies ⁴.

Pathology

Causes

The causes of oligohydramnios are protean and one way to simplify them is by using the mnemonic DRIPPC:

D:
- demise
- drugs: e.g. prostaglandin inhibitors (indomethacin)
R: renal abnormalities (from decreased urine output)
I: IUGR (intra-uterine growth restriction): 80% may occur from decreased renal perfusion due to sparing effect
P: premature rupture of membranes
- premature rupture of membranes (PROM)
- preterm premature rupture of membranes (PPROM)
P: post dates
C: chromosomal anomalies (especially if other anomalies are found)

Associations

Potter sequence
underlying fetal hypoxia and fetal cardiovascular compromise: from preferential flow to the fetal brain at the expense of diminished renal blood flow
twin pregnancy-related complications:
- twin to twin transfusion syndrome: in pump twin
maternal dehydration

Radiographic features

Antenatal ultrasound

Several sonographic criteria can be used which include:

four quadrants amniotic fluid index (AFI): <5 cm
two diameter pocket method: <1 x 1 cm or <15 cm²
maximum vertical pocket depth: <2 cm

Treatment and prognosis

Development of oligohydramnios early in pregnancy is generally a poor prognostic marker. Amnio-infusion can be attempted in severe cases if appropriate.

Complications

first-trimester oligohydramnios can result in failure of pregnancy in up to 95% from complications such as
- pulmonary hypoplasia: implies a very poor prognosis
- fetal limb contractures

See also

References changed:

2. Sivit C, Hill M, Larsen J, Kent S, Lande I. The Sonographic Evaluation of Fetal Anomalies in Oligohydramnios Between 16 and 30 Weeks Gestation. AJR Am J Roentgenol. 1986;146(6):1277-81. <a href="https://doi.org/10.2214/ajr.146.6.1277">doi:10.2214/ajr.146.6.1277</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/3518372">Pubmed</a>
3. Levine D, Goldstein R, Callen P, Damato N, Kilpatrick S. The Effect of Oligohydramnios on Detection of Fetal Anomalies with Sonography. AJR Am J Roentgenol. 1997;168(6):1609-11. <a href="https://doi.org/10.2214/ajr.168.6.9168737">doi:10.2214/ajr.168.6.9168737</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/9168737">Pubmed</a>
4. Chauhan S, Taylor M, Shields D, Parker D, Scardo J, Magann E. Intrauterine Growth Restriction and Oligohydramnios Among High-Risk Patients. Amer J Perinatol. 2007;24(4):215-21. <a href="https://doi.org/10.1055/s-2007-972926">doi:10.1055/s-2007-972926</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/17447191">Pubmed</a>
6. Johnson J, Chauhan S, Ennen C, Niederhauser A, Magann E. A Comparison of 3 Criteria of Oligohydramnios in Identifying Peripartum Complications: A Secondary Analysis. American Journal of Obstetrics and Gynecology. 2007;197(2):207.e1-8. <a href="https://doi.org/10.1016/j.ajog.2007.04.048">doi:10.1016/j.ajog.2007.04.048</a> - <a href="https://www.ncbi.nlm.nih.gov/pubmed/17689653">Pubmed</a>
2. Sivit C, Hill M, Larsen J, Kent S, Lande I. The Sonographic Evaluation of Fetal Anomalies in Oligohydramnios Between 16 and 30 Weeks Gestation. AJR Am J Roentgenol. 1986;146(6):1277-1281. <a href="https://doi.org/10.2214/ajr.146.6.1277">doi:10.2214/ajr.146.6.1277</a>
3. Levine D, Goldstein R, Callen P, Damato N, Kilpatrick S. The Effect of Oligohydramnios on Detection of Fetal Anomalies with Sonography. AJR Am J Roentgenol. 1997;168(6):1609-1611. <a href="https://doi.org/10.2214/ajr.168.6.9168737">doi:10.2214/ajr.168.6.9168737</a>
4. Chauhan S, Taylor M, Shields D, Parker D, Scardo J, Magann E. Intrauterine Growth Restriction and Oligohydramnios Among High-Risk Patients. Amer J Perinatol. 2007;24(4):215-221. <a href="https://doi.org/10.1055/s-2007-972926">doi:10.1055/s-2007-972926</a>
6. Johnson J, Chauhan S, Ennen C, Niederhauser A, Magann E. A Comparison of 3 Criteria of Oligohydramnios in Identifying Peripartum Complications: A Secondary Analysis. Am J Obstet Gynecol. 2007;197(2):207.e1-207.e8. <a href="https://doi.org/10.1016/j.ajog.2007.04.048">doi:10.1016/j.ajog.2007.04.048</a>