Comparing early and late intervention for Twin Reversed Arterial Perfusion Syndrome

Early Versus Late Intervention for Twin Reversed Arterial Perfusion Sequence: an Open-label Randomized Controlled Trial: TRAPIST - TRAP Intervention STudy

Phase 4 Interventional Universitaire Ziekenhuizen KU Leuven · NCT02621645

This study is testing whether treating Twin Reversed Arterial Perfusion syndrome earlier or later during pregnancy helps improve outcomes for the affected twins.

Quick facts

PhasePhase 4
Study typeInterventional
Enrollment126 (estimated)
Ages18 Years and up
SexFemale
SponsorUniversitaire Ziekenhuizen KU Leuven Academic / other
Locations14 sites (Houston, Texas and 13 other locations)
Trial IDNCT02621645 on ClinicalTrials.gov

What this trial studies

This multi-center open-label randomized controlled trial aims to evaluate the effectiveness of early intervention (12.0-14.0 weeks) versus late intervention (16.0-19.0 weeks) for managing Twin Reversed Arterial Perfusion (TRAP) syndrome. Women diagnosed with TRAP sequence between 11.6 and 13.6 weeks will be randomly assigned to either intervention group using a web-based application for randomization. The interventions will involve ultrasound-guided procedures to reduce the acardiac twin, with outcomes assessed by intention-to-treat analysis. The study will be conducted under sterile conditions and local anesthesia or conscious sedation by experienced operators.

Who should consider this trial

Good fit: Ideal candidates are women aged 18 or older with a monochorionic diamniotic twin pregnancy diagnosed with TRAP sequence between 11.6 and 13.6 weeks.

Not a fit: Patients with severe maternal medical conditions, major anomalies in the pump twin, or those who cannot undergo the intervention due to anatomical issues may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could improve outcomes for pregnancies affected by TRAP syndrome, potentially reducing complications for the healthy twin.

How similar studies have performed: Other studies have explored interventions for TRAP syndrome, but this specific comparison of early versus late intervention is novel.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* TRAP sequence in a monochorionic diamniotic twin pregnancy diagnosed between 11.6 and 13.6 weeks, as determined by the crown-rump length of the pump twin in spontaneous conceptions and by the date of insemination or embryonic age at replacement in pregnancies resulting from subfertility treatment
* Women aged 18 years or more, who are able to consent
* Anatomically normal pump twin
* Provide written informed consent to participate in this randomized controlled trial, forms being approved by the Ethical Committees

Exclusion Criteria:

* Contraindication for an intervention due to a severe maternal medical condition or threatening miscarriage
* Inaccessibility of the acardiac twin due to a retroverted uterus, severe maternal obesity, uterine fibroids, bowel or placental superposition
* A major anomaly in the pump twin, requiring surgery or leading to infant death or severe handicap
* Spontaneous arrest of the reverse flow and/or pump twin demise at diagnosis

Where this trial is running

Houston, Texas and 13 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Twin Reversal Arterial Perfusion SyndromemonochorionicTRAPacardiac twin
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.