A case of twin reversed arterial perfusion (TRAP) sequence managed conservatively

Abstract

The TRAP sequence, also known as acardiac twinning is a rare complication that is unique to monochorioinic multiple pregnancies affecting 1% of monochorioinic pregnancies and about 1 in 35000 of all pregnancies. In TRAP, blood flows from the umbilical artery of the pump twin to the umbilical artery of the perfused twin through artery to artery (AA) anastomosis. The perfused twin has poor development of the upper extremities and the normal or pump twin is at risk of a poor perinatal outcome. This is a report of a patient with TRAP sequence diagnosed in the second trimester who was managed conservatively and had a good outcome for the normal twin.

“The Strange Case of Dr Pump and Mr Acardiac”: The Twin Reversed Arterial Perfusion (TRAP) Sequence in Two Monochorionic Monoamniotic (MCMA) Twin Pregnancies—Diagnosis, Prognosis and Management: Review of Literature

“…To the best of our knowledge, the diagnosis of acardia is almost always made in the second [17][18][19][20][21][22][23] or third trimester [24][25][26] of gestation by means of transabdominal ultrasound. In some cases, the existence of the TRAP Sequence could even remain unknown until delivery [27,28], when the childbirth is preceded or followed by ambiguous amorph mass expulsion.…”

“…According to Moore, if the ratio between the weight of the acardiac twin and that of the pump twin (APTW) is greater than 70:100 (0.7), the incidences of preterm delivery, polyhydramnios, and heart failure for the pump twin are 90%, 40%, and 30% respectively; when APTW is lower than 0.7, the incidences are 75%, 30%, and 10% [9]. In the literature, Moore's weight comparison between the monster and the normal twin has widely been used with sound confirmations of its goodness for predicting the outcome of TRAP pregnancies [18][19][20]22,24]. If we wanted to apply Moore's concept in our Case Report One, the estimated weight of our anomalous twin, based on a maximum length of 6.7 cm, was approximately 42.5 g. As per the William package, pump twin measured 480 g (Figure 3A), yielding a 0.09 ratio.…”