Acardiac twin is a rare anomaly that occurs 1% in monochorionic twins and 1 in 35,000 pregnancies overall. Acardiac twin, also known as twin-reversed arterial perfusion (TRAP) sequence, involves a "pump" or donor twin perfusing a recipient or "acardiac" twin through vascular (usually arterial-arterial and venous-venous) anastomoses. Perinatal mortality rate for the pump twin has been reported to be 50~75%, mainly as a result of polyhydramnios, preterm labor, and congestive heart failure. Therefore, occlusion of the circulation to the acardiac twin has been recommended to improve perinatal outcome of the pump twin. Radiofrequency ablation of the acardiac twin effectively protects the pump twin from high-output cardiac failure and death. We report our experience in the treatment of patients with TRAP sequence using radio frequency ablation to stop perfusion to the acardiac twin.

Cesarean scar pregnancy, in which the pregnancy is implanted at the previous cesarean scar, is a very rare form of ectopic pregnancy. A delay in diagnosis can lead to uterine rupture, massive hemorrhage, and serious maternal morbidity. However, the optimal treatment is unknown. We experienced a case of viable cesarean scar pregnancy diagnosed at 13 weeks of gestation treated with uterine artery embolization and report with a brief of literatures.

Objective: To evaluate and compare the rate and etiologies of second trimester pregnancy loss in monochorionic (MC) or dichorionic (DC) twins, and natural or assisted reproductive technology (ART) twins. Methods: Between January 1997 and December 2008, there were 146 cases of second trimester twin pregnancy losses (between 12 and 24 weeks gestation) from 2,467 twin pregnancies. They were divided into four groups according to chorionicity and fertilization. Chorionicity was established by ultrasound at early gestation and confirmed by histologic examination after delivery. From a total of 2,467 twin deliveries, 392 MC, 2058 DC, and 17 unknown chorionicity were observed. Fertilization methods were classified as 736 natural, 1,590 ART, and 141 unknown conceptions. The pregnancy loss rate and possible mechanisms were compared in each group. Results: During the study period, there were 43 MC, 86 DC, and 17 unknown chorionicities and 45 natural, 78 ART, and 23 unknown fertilizations. Total twin pregnancy loss rate was 5.9% (146/2,467), with 11.0% (43/392) and 4.2% (86/2,058) for MC twin group and DC twin group, respectively. Likewise, it was 6.1% (45/736) and 4.9% (78/1,590) for natural twin group and ART twin group. The most common cause was intrauterine fetal death (IUFD) in 22 (51.2%) in MC twin group and preterm premature rupture of membranes (PPROM) in 40 (46.5%) in DC twin group, followed by preterm labor (PTL) in 37 (43%). In natural pregnancy, IUFD was the most common etiology in 20 (44.5%) and for ART twin group, it was PTL in 35 (44.9%). Conclusion: Twin pregnancy loss rate was higher in MC twin group compared with DC twin group in the second trimester. MC twin group had a higher incidence of IUFD as a cause of second trimester pregnancy loss. The etiologies in DC twin group were PPROM and PTL. It is suggested that antenatal care in twin pregnancy should be explored for preventing fetal loss and promoting neonatal well-being.