Fetal Medicine Unit, Academic Department of Obstetrics and Gynaecology, St George's Hospital Medical School, London, UK.
Ultrasound Obstet Gynecol. 2010 Feb;35(2):201-4. doi: 10.1002/uog.7501.
To assess the prevalence of cord entanglement and perinatal outcome in a large series of monoamniotic twin pregnancies and to review the recent literature on similar published large series.
Prospective observational study of all prenatally detected cases of monoamniotic twin pregnancies during an 8-year period in a tertiary fetal medicine unit. A Medline database review for publications since 2000 containing five or more cases of monoamniotic pregnancies that showed data on cord entanglement and perinatal outcome was also undertaken.
A total of 32 monoamniotic pregnancies were diagnosed during the study period, including three conjoined twins, seven pregnancies with twin reversed arterial perfusion (TRAP) syndrome, three surgical pregnancy interruptions for discordant fetal abnormality and one miscarriage before 16 weeks' gestation. The remaining 18 monoamniotic pregnancies were included in the study analysis. All monoamniotic pregnancies were complicated with antenatal cord entanglement diagnosed by B-mode and color Doppler ultrasound. There were 34 live births and a double intrauterine death diagnosed at 19 + 2 weeks' gestation. There were two late neonatal deaths, one from congenital complete heart block and the other after surgery for transposition of the great arteries. The overall perinatal loss rate was 11.1% after 16 weeks and 5.9% after 20 weeks' gestation. The cumulative rates of cord entanglement and perinatal mortality in the reviewed literature were 74% and 21%, respectively.
Umbilical cord entanglement is present in all monoamniotic twins when it is systematically evaluated by ultrasound and color Doppler. Perinatal mortality in monoamniotic twins is mainly a consequence of conjoined twins, TRAP, discordant anomaly and spontaneous miscarriage before 20 weeks' gestation. Expectantly managed monoamniotic twins after 20 weeks have a very good prognosis despite the finding of cord entanglement. The practice of elective very preterm delivery or other interventions to prevent cord accidents in monoamniotic twins should be re-evaluated.
评估大型单羊膜囊双胎妊娠中脐带缠绕的发生率和围产儿结局，并复习近年来类似的大型系列文献。
对 8 年内三级胎儿医学中心产前诊断的所有单羊膜囊双胎妊娠病例进行前瞻性观察研究。还对 2000 年以来发表的包含 5 例或以上单羊膜囊妊娠病例且有脐带缠绕和围产儿结局数据的文献进行了 Medline 数据库综述。
研究期间共诊断出 32 例单羊膜囊妊娠，包括 3 例联体双胎、7 例双胎反向动脉灌注（TRAP）综合征、3 例因胎儿异常不一致而行手术中止妊娠、1 例 16 周前流产。其余 18 例单羊膜囊妊娠纳入研究分析。所有单羊膜囊妊娠均伴有产前 B 型和彩色多普勒超声诊断的脐带缠绕。共分娩 34 例活产儿，19+2 周时诊断为双胎宫内死亡。有 2 例新生儿晚期死亡，1 例死于先天性完全性心脏阻滞，另 1 例死于大动脉转位手术后。16 周后和 20 周后总的围产儿丢失率分别为 11.1%和 5.9%。文献综述中脐带缠绕和围产儿死亡率的累积率分别为 74%和 21%。
当系统地通过超声和彩色多普勒评估时，所有单羊膜囊双胎均存在脐带缠绕。单羊膜囊双胎的围产儿死亡率主要是由于联体双胎、TRAP、不一致的异常和 20 周前自发性流产所致。20 周后经期待治疗的单羊膜囊双胎尽管发现脐带缠绕，但预后非常好。应重新评估在单羊膜囊双胎中选择性行极早产分娩或其他干预以预防脐带意外的做法。
