What is a twin reversed arterial perfusion (TRAP)?
This phenomenon occurs only in a twin pregnancy where the babies share the same placenta. The incidence is about 1 in every 35,000 identical twin births. One twin is normally developed and referred to as the ‘pump’ twin. He pumps blood for himself as well as for the other twin. The other twin is not fully developed and often lacks any personable features. This twin does not have a heart and is referred to as the ‘acardiac’ or abnormal twin. The term ‘reversed perfusion’ is used because the blood enters the undeveloped twin through the vessels in the opposite direction. This sequence of events places the normal twin at risk for heart failure. Left untreated, there is a 50%-75% chance of mortality for the normal twin. The cause of TRAP is unknown. What testing is recommended during the pregnancy? Ultrasound examination can confirm the diagnosis and will be used to monitor the pregnancy. The size of both babies is an important determinant for the outcome of the normal twin. If the estimat
