Abstract
Acardiac twin or TRAP (twin reversed arterial perfusion) sequence is a rare complication of monochorionic pregnancies. In these cases, the heart is either absent or non-functional. It’s controversial whether conservative management or therapeutic treatment is better in TRAP-sequence. In this case, we present a 19-years old, primigravida diagnosed with spontaneous monochorionic monoamniotic twin pregnancy at 7th week of gestation. One of the fetuses had a crown-rump length of 8 mm and fetal heart rate 122/minute while the other one had a crown-rump of 7 mm with no detected fetal heartbeat. At the 11th week of gestation, the acardiac twin continued growing despite the absence of the fetal heart beat and fetal extremities. The cranium could not be evaluated clearly. The diagnosis of TRAP sequence was confirmed by the reversed direction of flow observed in the umbilical artery. Since the patient and her husband did not want any intervention, no interventional diagnostic and treatment modalities were applied. Preterm labor started at the 32th week. Because the presentations were transverse and breech, pump and acardiac fetus, respectively, a cesarean delivery was performed. A healthy female baby, weighing 1650 gr with APGAR scores of 9-10, first and fifth minutes, respectively, was delivered along with the acardiac fetus which was 1550 gram in weight, fetal heart beat negative, with upper and lower extremity deformities. The uniqueness of the present case is that there was no significant difference in the weight of both twins. The acardiac twin was as large as the pump twin. Except for twenty days hospitalization because of neonatal respiratory distress syndrome, which was a consequence of preterm labor, there were no problems with the pump twin even though managed conservatively. In monochorionic twin pregnancies, when one of the twins is found to be fetal heartbeat negative and it continues to grow with concomitant structural abnormalities, the TRAP sequence should come to mind. If the acardiac fetus is small and the pump fetus has no complications, the conservative approach can be considered. Our goal should be to deliver the pump twin with minimal complications. To achieve this, follow-ups and treatment should be individualized for each patient, the pump fetus should be monitored closely.
Highlights
Acardiac twin or TRAP sequence is a rare complication of monochorionic pregnancies
The heart is either absent or non-functional. It is seen in one percent of monozygotic twins, the incidence in all births is approximately 1/35,000.1 The absence of one fetal heartbeat in twin pregnancies may be diagnosed in the first trimester
The acardiac twin is detected to continue growing despite the absence of a fetal heartbeat and concomitant fetal anomalies
Summary
Acardiac twin or TRAP (twin reversed arterial perfusion) sequence is a rare complication of monochorionic pregnancies In these cases, the heart is either absent or non-functional. The nonviable twin is perfused with retrograde blood flow from the other twin that flows through arterioarterial anastomoses; the blood returns to the normal twin by venovenous anastomoses that bypass the placenta Because these vessels carry less oxygenated blood and the flow is asymmetrical, the result is malformations mostly seen in the cranium and upper extremities.[3] In our case we present an acardius anceps that reached the same size as the pump fetus and was followed conservatively. The second fetus CRL was 39 mm, fetal heartbeat was negative, cranial structures and upper limbs could not be evaluated clearly. The acardiac fetus continued to grow at the same rate as the pump fetus, lower extremities were observed, upper structures and head were not evaluated clearly.
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