Case Report of Autopsy and Placental Examination After Radiofrequency Ablation of an Acardiac Twin

Novel autopsy and genetic findings in an acardiac twin: case report and literature review

Twin reversed arterial perfusion (TRAP) sequence is a rare complication of monochorionic twinning whereby a donor twin perfuses an acardiac twin via aberrant vascular anastomoses. The resulting paradoxical retrograde blood flow supplying the acardiac twin is oxygen-poor, leading to some of the most severe malformations encountered in humans. Though the first descriptions of acardiac twins date back to at least the 16th century, the pathophysiologic processes which underpin the development of TRAP sequence are still being elucidated. Theories on the pathogenesis of TRAP sequence include deficiencies intrinsic to the embryo and primary abnormalities of the placental vasculature. Autopsy studies continue to provide clues to the underlying pathogenesis of TRAP sequence, and the characterization of the spectrum of manifestations that can be observed in acardiac twins. Herein, we present the clinical, autopsy, and molecular findings in a unique case of TRAP sequence. Novel findings include a primitive cloaca-like structure and chromosomal aberrations involving 6q11.1 and 15q25.1.

"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

The Twin Reversed Arterial Perfusion (TRAP) Sequence is an extremely rare complication of monochorionic twin pregnancies, with one severely malformed twin (the "acardiac") lacking autonomous placental blood supply and being perfused by the co-twin (the "pump"), through arterio-arterial (and sometimes also veno-venous) vascular anastomoses located on the placental surface. The prognosis is poor: mortality is 100% in the acardiac twin because of its severe malformations and about 50-55% in the pump twin, mainly due to heart failure and prematurity. So, the goal of perinatal management of the TRAP twin pregnancy is to deliver a healthy and near-term pump twin without heart failure or fetal hydrops. Intuitively, the earlier the diagnosis, the better the outcome. Herein, we report two cases of monochorionic monoamniotic (MCMA) twin pregnancies complicated by the TRAP Sequence, which are of interest since the objective of early diagnosis was achieved by means of transvaginal and 3D ultrasound, two techniques which revealed themselves as being useful to this purpose but are underused in the literature. The second aim of this study is to provide an overview of literature data about the diagnosis, prognosis establishment, and management of this rare condition, which are still debated and unclear due to negligible poor-quality evidence.

Twin reversed arterial perfusion (TRAP) sequence: A case report and a brief literature review

Twin reversed arterial perfusion (TRAP) sequence is rare in monochorionic twin pregnancies. TRAP sequence is distinct from other multifetal pregnancies in that one of the twins has normal anatomy while the other twin has a varied amount of characteristic abnormal features. In the literature, mortality is reported 100% in the abnormal twin. We report 1 case of TRAP sequence at our institution in which the diagnosis of TRAP sequence was missed in the first trimester at another hospital. The patient, a 33-year-old G1P0A0, did not have any follow-up after her first scan until the routine second-trimester ultrasound at our institution. Both the radiologist and the sonographer did not appreciate the differential diagnosis of TRAP sequence in their clinical decision-making. The TRAP diagnosis was established after the ultrasound performed at the fetal assessment unit in our hospital. Radiofrequency ablation (RFA) procedure was performed to give the normal twin a chance to survive, but unfortunately, the prognosis was poor in this case. We conclude that diagnosing a TRAP sequence is very important early in the pregnancy for a positive outcome in the normal twin. A robust collaboration among radiologists and obstetricians is vital for the best outcome of the normal twin.

TRAP Sequence in Monochorionic/Monoamniotic (MC/MA) Discordant Twins: Two Cases Treated with Fetoscopic Laser Surgery

INTRODUCTION

Ablation of the acardiac twin umbilical cord in the TRAP protects the normal donor twin.

MATERIALS AND METHODS

Two case descriptions, one of interstitial laser photocoagulation and one of laser umbilical cord occlusion (L-UCO) of the acardiac twin in monochorionic monoamniotic pregnancies are reported.

RESULTS

L-UCO in two pregnancies with TRAP syndrome in the second trimester resulted in intrauterine fetal death in both cases after 1 month. Case 1 had no detectable cause of fetal death. Case 2 had rupture of the amniotic sac causing anhydramnios and acute chorioamnionitis. A groove on the umbilical cord of the normal twin indicated a cord stricture due to cord entanglement.

CONCLUSION

Our experience confirms that the best timing and optimal treatment of MC/MA twins complicated by TRAP sequence still remains a controversial clinical issue. Cord entanglement may continue be a potential clinical risk factor for adverse perinatal outcome even after ablation therapy.