Question: What would the ICD-10 code be for TRAP syndrome? The patient is carrying twins. However, one of the twins is malformed, and twin A’s heart is carrying full responsibility for both twins. They are not conjoined. What should I report? California Subscriber Answer: TRAP stands for “twin reversed arterial perfusion sequence,” and it happens rarely in twin monochorionic pregnancies. You won’t find any specific code for this, but it is a severe variation of TTTS (Twin to Twin Transfusion Syndrome), You will choose one of the following codes, based on the trimester: If your physician is looking for the diagnosis for the baby after it is born, the code is P02.3 (Newborn [suspected to be] affected by placental transfusion syndromes).