[Analysis of clinical characteristics of discordant structural malformations in one of monochorionic diamnionic twins].

To analyze the clinical characteristics of structural malformations in one of monochorionic diamnionic twins (MCDA). The clinical data of 77 MCDA patients with structural malformations diagnosed by ultrasound were retrospectively reviewed from January 2012 to May 2017. The distribution of structural malformations, prenatal chromosomal karyotyping and pregnancy outcomes were analyzed. (1)Among the 77 MCDA patients with structural malformations, the single malformation accounted for 79%(61/77), the multiple malformations accounted for 21%(16/77). And there were a total of 94 types of malformations, the top three malformations were neurological malformations (32%, 30/94), cardiovascular malformations (29%, 27/94) and twin reversed arterial perfusion sequence (TRAPS;10%,9/94).(2)Among the 77 patients with structural malformation, 64 cases (83%, 64/77) were examined for fetal chromosomes, of whom 14 cases (22%,14/64) were examined for fetal chromosomes of both twins, with 1 case (1/14) of discordant fetal chromosome. (3)Among the 77 patients, 4 cases (5%, 4/77) with severe fetal malformations terminated pregnancy. Totally 29 cases (38%,29/77) with severe malformations were treated with selective fetal reduction, among whom 7 cases (24%, 7/29) experienced unexplained fetal death within 24 hours after the operation; 2 cases (7%, 2/29) happened inevitable abortion, and 2 cases (7%, 2/29) underwent unexplained fetal death during the late pregnancy. Of the remaining 44 patients (57%,44/77) with expectant treatment, 13 cases (30%,13/44) occurred twin transfusion syndrome (Ⅱ-Ⅳ), and were treated with fetoscopic laser occlusion. Eight patients had 2 survival twins, 4 patients delivered 1 survival twin, and 1 patient had dead twins. The most common malformations in MCDA twins are the nervous malformations, cardiovascular malformations and TRAPS. The chromosome karyotype of MCDA twins with structural malformations are sometimes discordant, and separate samling of the twins is suggested for prenatal diagnosis. Selective fetal reduction could be given to severe structural malformation in MCDA patients safely and effectively. For non-severe structural malformation in MCDA patients with twin transfusion syndrome, fetoscopic laser occlusion is safe and effective.