Midtrimester isolated oligohydramnios in monochorionic diamniotic multiple gestations

Area of Science:

• Maternal-fetal medicine
• Perinatology
• High-risk pregnancies

Background:

• Monochorionic diamniotic (MCDA) twins are at increased risk for complications.
• Isolated oligohydramnios (iOligo) in mid-gestation is a concerning finding in MCDA twins.
• The natural history and outcomes of iOligo require further elucidation.

Purpose of the Study:

• To describe the natural history of MCDA twins diagnosed with mid-trimester iOligo.
• To evaluate the perinatal outcomes in this specific twin gestation group.
• To identify progression to twin-twin transfusion syndrome (TTTS) or selective intrauterine growth restriction (sIUGR).

Main Methods:

• Retrospective study of 33 MCDA twin pregnancies with mid-trimester iOligo.
• Patients were initially referred for suspected TTTS or sIUGR.
• Defined iOligo as a maximum vertical pocket ≤2 cm in one sac and normal fluid in the co-twin.

Main Results:

• 4.3% of complicated MCDA gestations presented with iOligo.
• 69.7% of cases progressed to TTTS or sIUGR Type II.
• Laser surgery in Group B (progressed cases) resulted in 100% survival of at least one twin, with 46.7% dual survivorship.

Conclusions:

• The majority of MCDA twins with mid-trimester iOligo experience fetal growth restriction.
• These pregnancies frequently progress to TTTS or sIUGR Type II.
• Early diagnosis and management are critical for improving perinatal outcomes.