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Twin Reversed Arterial Perfusion (TRAP) Sequence: Proposal for Morphologic Classification System Predicting Natural
1Department of Ultrasound Diagnosis, Maternal and Child Health Hospital of Hubei Province, Wuhan, China.
Objective:
To establish a new classification system for Twin Reversed Arterial Perfusion (TRAP) sequence based on specific skeletal morphological characteristics, and to evaluate its prognostic relevance in expectantly managed.
Methods:
Single center retrospective cohort study of TRAP sequence cases between February 2001 and April 2022 that were expectantly managed. Cases were classified into five morphological types: Type I (Hemiacardius), Type II (Acardius Holosomus), Type III (Acephalus Trunk), Type IV (Acephalus Acormus), and Type V (Acardius Amorphous). Pump twin outcomes for prognosis were compared among the five types.
Results:
Of 116 cases expectantly managed, the most common type was type III (41.4%), followed by type II (23.3%), type I (17.2%), type IV (7.8%), and type V (10.3%). Among these 116 cases, 29 (25.0%) had favorable outcomes, whereas 87 (75.0%) had an adverse outcome. Survival rates differed significantly by type (p = 0.001): Type V, 66.7% (8/12); Type IV, 33.3% (3/9); Type II, 22.2% (6/27); Type III, 18.8% (9/48); and Type I, 15.0% (3/20).
Conclusions:
In this series of expectantly managed TRAP-cases, pump twin survival was highest when the acardiac twin exhibited minimal structural development. Early sonographic classification may support prenatal counseling in the TRAP sequence.
