Managing TRAP Sequence Conservatively: A Case Report of Full-Term Pregnancy With Favorable Outcome

Area of Science:

• Perinatology
• Maternal-Fetal Medicine
• Reproductive Medicine

Background:

• Acardiac twinning, or Twin reversed arterial perfusion (TRAP) sequence, is a rare complication exclusive to monochorionic twin pregnancies.
• It arises from abnormal placental vascular connections, causing retrograde blood flow from a healthy "pump" twin to a malformed, acardiac twin.
• The condition carries a high mortality rate for both the acardiac twin (100%) and the pump twin (50-55%).

Purpose of the Study:

• To report a case of TRAP sequence diagnosed in the second trimester.
• To highlight the potential for conservative management in select TRAP sequence cases.
• To emphasize the importance of monitoring the hemodynamics of the pump twin.

Main Methods:

• Case presentation of a 30-year-old patient with G3 P1 A1.
• Diagnosis of an acephalus acardiac twin via routine second-trimester ultrasound.
• Continued pregnancy to 38 weeks with elective Cesarean section due to absence of hemodynamic compromise in the normal twin.

Main Results:

• An acephalus acardiac twin was diagnosed via ultrasound.
• The pregnancy was successfully continued to term without signs of hydrops or cardiac failure in the pump twin.
• An elective Cesarean section was performed at 38 weeks gestation.

Conclusions:

• Conservative management of TRAP sequence can be successful when the pump twin is hemodynamically stable.
• Careful monitoring for hydrops or cardiac compromise in the pump twin is crucial for guiding management decisions.
• This case underscores that intervention is not always necessary in TRAP sequence if the healthy twin is unaffected.