Overton T G, Denbow M L, Duncan K R, Fisk N M
Centre for Fetal Care, Imperial College School of Medicine, Queen Charlotte's, London, UK.
Ultrasound Obstet Gynecol. 1999 Feb;13(2):140-2. doi: 10.1046/j.1469-0705.1999.13020140.x.
Monoamniotic twinning occurs in only 1% of twin pregnancies, but carries a high perinatal mortality rate. Early and reliable diagnosis is essential if attempts are to be made to reduce the complication rate. We report color Doppler demonstration of cord entanglement in the first trimester, which is diagnostic of monoamnionicity.
Two patients with twin pregnancies were examined in the first trimester with pulsed and color Doppler insonation of their umbilical arteries.
Cord entanglement was suspected and proved by demonstrating differing fetal heart rate patterns in the same direction on umbilical artery Doppler analysis of a common mass of cord vessels. Following appropriate counselling, medical amnioreduction was induced at 20 weeks of gestation to reduce fetal movements and worsening cord entanglement. Delivery was by elective Cesarean section at 32 weeks' gestation and monoamnionicity was confirmed.
We report a new sign for the demonstration of monoamnionicity in twin pregnancies in the first trimester. This should improve the reliability of early diagnosis, but further studies are required to confirm that, if cord entanglement occurs, it is usually present by the end of the first trimester.
单羊膜囊双胎妊娠仅占双胎妊娠的1%，但围产儿死亡率很高。若要降低并发症发生率，早期且可靠的诊断至关重要。我们报告了孕早期彩色多普勒显示的脐带缠绕情况，这可诊断单羊膜囊双胎妊娠。
两名双胎妊娠患者在孕早期接受了脐动脉的脉冲和彩色多普勒检查。
通过对一团共同的脐带血管进行脐动脉多普勒分析，发现相同方向上不同的胎儿心率模式，从而怀疑并证实了脐带缠绕。经过适当的咨询后，在妊娠20周时进行了药物性羊水减量，以减少胎儿活动并减轻脐带缠绕。妊娠32周时行择期剖宫产分娩，证实为单羊膜囊双胎妊娠。
我们报告了一种在孕早期显示双胎妊娠单羊膜囊双胎的新征象。这应能提高早期诊断的可靠性，但需要进一步研究以证实，如果发生脐带缠绕，通常在孕早期结束时就已存在。
