Adverse outcomes in monochorionic twins with amniotic fluid abnormalities without TTTS: A Case-Control study

Area of Science:

• Perinatology
• Maternal-Fetal Medicine
• High-Risk Obstetrics

Background:

• Monochorionic diamniotic (MCDA) twins present unique challenges, particularly when amniotic fluid abnormalities arise without meeting diagnostic criteria for twin-twin transfusion syndrome (TTTS).
• These ambiguous fluid findings cause concern for clinicians and families regarding potential adverse outcomes.
• Understanding the natural history of these borderline abnormalities is crucial for appropriate management.

Purpose of the Study:

• To describe the natural history and clinical significance of amniotic fluid abnormalities in MCDA twins that do not meet established criteria for TTTS.
• To identify associated complications and outcomes in these pregnancies.

Main Methods:

• A retrospective case-control study reviewed ultrasounds and clinical records of MCDA twin gestations from 2018-2022.
• Cases with unexplained fluid abnormalities were categorized, excluding those with clear TTTS, selective fetal growth restriction (sFGR), twin-anemia polycythemia sequence (TAPS), structural anomalies, or insufficient scan data.
• A control group with normal fluid imaging throughout gestation was used for comparison.

Main Results:

• Among 140 cases with non-diagnostic fluid abnormalities, compared to 224 controls, increased rates of TTTS (41%), TAPS (8%), new sFGR (11%), and laser intervention (36%) were observed.
• Fetal demise occurred more frequently in cases (11% vs 1%).
• Maternal admissions for surveillance and earlier delivery (33.1 vs 35.1 weeks) were also significantly higher in the case group.

Conclusions:

• Amniotic fluid abnormalities in MCDA twins, even if not meeting TTTS criteria, serve as a critical warning sign.
• These findings are associated with a significantly higher risk of adverse pregnancy outcomes, including fetal demise and the need for interventions.
• Close monitoring and timely intervention are warranted for MCDA twins presenting with ambiguous fluid abnormalities.