Vayssière C F, Heim N, Camus E P, Hillion Y E, Nisand I F
Department of Obstetrics and Gynecology, Université de Paris V Faculte de Medicine, Centre Hospitalier Intercommunale Leon Touhladjian, Poissy, France.
Am J Obstet Gynecol. 1996 Dec;175(6):1529-33. doi: 10.1016/s0002-9378(96)70102-3.
Our aim was to determine whether chorionicity in twin gestations can be diagnosed by use of high-frequency ultrasonography to count the layers of intraamniotic membrane.
This prospective study of 66 twin pregnancies between 13 and 38 weeks' gestation used transabdominal ultrasonography at 10 MHz. The pregnancy was classified as monochorionic when two layers were counted and as dichorionic when three or four layers were counted. The findings of the examiner, who had no other information about chorionicity, were compared with those of the histopathologic examination of the placenta.
Ultrasonography allowed chorionicity to be determined correctly in 60 of 63 cases (95%; 100% in the second trimester and 92% in the third. The predictive value for dichorionicity was 100% (48/48) and the sensitivity 94% (48/51). The 12 monochorionic diamniotic pregnancies in which the membrane was visualized were all correctly diagnosed. In a thirteenth case, with severe oligohydramnios, the membrane could not be seen. Two patients were lost to follow-up. In 95% of the cases (63/66) only one examination was required to diagnose chorionicity. Intraobserver variability was 0% (0/26). Interobserver variability, tested by photographs, was 3% (2/65).
This technique should be the first-line method for determining chorionicity in the second and third trimesters because it is the most effective. Its excellent reproducibility may be attributable to the use of high-frequency ultrasonography.
我们的目的是确定能否通过使用高频超声检查羊膜腔内的层数来诊断双胎妊娠的绒毛膜性。
这项前瞻性研究纳入了66例孕13至38周的双胎妊娠，使用10MHz经腹超声检查。当计数为两层时，妊娠被分类为单绒毛膜性；当计数为三层或四层时，妊娠被分类为双绒毛膜性。将对绒毛膜性没有其他信息的检查者的检查结果与胎盘组织病理学检查结果进行比较。
超声检查在63例中的60例（95%）中正确确定了绒毛膜性（孕中期为100%，孕晚期为92%）。双绒毛膜性的预测值为100%（48/48），敏感性为94%（48/51）。12例可见胎膜的单绒毛膜双羊膜囊妊娠均被正确诊断。在第13例中，由于严重羊水过少，胎膜未见。2例患者失访。95%的病例（63/66）仅需一次检查即可诊断绒毛膜性。观察者内变异性为0%（0/26）。通过照片测试的观察者间变异性为3%（2/65）。
这项技术应作为孕中期和孕晚期确定绒毛膜性的一线方法，因为它是最有效的。其出色的可重复性可能归因于使用了高频超声检查。
