What is the management of oligohydramnios?

Management of Oligohydramnios

Oligohydramnios requires intensive fetal surveillance and should be managed based on gestational age, severity, and associated conditions, with delivery timing determined by these factors to reduce the risk of stillbirth. 1, 2

Definition and Diagnosis

• Oligohydramnios is defined as either an amniotic fluid index (AFI) < 5 cm or a maximal vertical pocket (MVP) < 2 cm 1, 2
• The maximal vertical pocket (MVP) measurement is preferable to AFI as it results in fewer false-positive diagnoses and reduces unnecessary obstetric interventions 1, 2
• Ultrasound confirmation is essential for diagnosis 2

Risk Assessment and Evaluation

• Oligohydramnios is an independent risk factor for stillbirth (OR 2.6; 95% CI 2.1-3.2) 1, 2
• Associated with increased maternal morbidity including hemorrhage, fetal malposition, and higher cesarean delivery rates 3
• Associated with adverse fetal/neonatal outcomes including stillbirth, neonatal death, low birth weight, and preterm birth 3
• Evaluate for potential causes:
  • Fetal anomalies, particularly genitourinary abnormalities 4
  • Premature rupture of membranes 4
  • Uteroplacental insufficiency (growth restriction, post-term pregnancy) 4
  • Twin-twin transfusion syndrome in monochorionic twins 2
  • Maternal conditions (hypertension, diabetes) 4

Management Protocol

Antenatal Surveillance

• Initiate intensive fetal surveillance at diagnosis if after viability 2, 4:
  • Weekly non-stress tests (NST) or biophysical profile (BPP)
  • Regular ultrasound assessment of amniotic fluid volume
  • Consider modified BPP (NST + AFI) for comprehensive assessment 1, 2
• Perform Doppler studies of umbilical artery if growth restriction is suspected 1, 2

Management Based on Gestational Age

Term (≥37 weeks)

• Consider delivery at term for isolated oligohydramnios, even with reassuring fetal testing 2
• Delivery is indicated if associated with other complications such as fetal growth restriction 2

Late Preterm (34-37 weeks)

• Consider delivery at 34-37 weeks for oligohydramnios associated with fetal growth restriction 2
• If no other complications exist, close monitoring with delivery by 37 weeks 2

Early Preterm (<34 weeks)

• Management depends on severity and associated conditions 2:
  • Continue surveillance with possible prolongation of pregnancy if stable
  • Consider earlier delivery based on degree of abnormality and associated complications
• Administer antenatal corticosteroids for fetal lung maturity if delivery anticipated before 34 weeks 2

Intrapartum Management

• Continuous fetal monitoring during labor 4
• Consider amnioinfusion during labor to reduce risk of variable decelerations and improve neonatal outcomes 4
• Be prepared for potential complications including fetal distress and cesarean delivery 3

Special Considerations

Twin-Twin Transfusion Syndrome (TTTS)

• In monochorionic diamniotic twins, oligohydramnios (MVP < 2 cm) in one sac with polyhydramnios (MVP > 8 cm) in the other meets criteria for stage I TTTS 1, 2
• Serial ultrasound evaluation every 2 weeks is recommended for all monochorionic diamniotic twins 1, 2
• Management depends on TTTS staging 1, 2:
  • Stage I: Expectant management with weekly surveillance
  • Stage II-IV (16-26 weeks): Fetoscopic laser photocoagulation of placental anastomoses
  • Beyond 26 weeks: Individualized management based on gestational age and severity

Isolated Oligohydramnios

• Despite reassuring fetal testing, isolated oligohydramnios remains a risk factor for adverse outcomes 1, 3
• Even in the absence of other complications, close monitoring is essential due to increased risk of stillbirth 1, 2

Monitoring Protocol

• Perform comprehensive fetal anatomic survey, focusing on genitourinary tract 4
• Consider karyotype testing if structural anomalies are present 4
• Monitor fetal growth closely due to association with growth restriction 3
• Assess maternal condition for hypertension, diabetes, or other significant illness 4