Supplementary Material for: Prenatal Diagnosis of a Spontaneous Monochorionic Five-Amniotic Quintuplet Pregnancy

Objectives: It is the aim of this study to report on the prenatal diagnosis and course of a spontaneous monochorionic (MC) 5-amniotic (5A) quintuplet pregnancy which is such a rare event that it has up to now never been described antenatally. Case Report: A spontaneous MC 5A quintuplet pregnancy was diagnosed at 12 weeks by 2D ultrasound. Video tapes (2D and 4D) were made showing that 2D ultrasound still better documented simultaneous visualization of all quintuplets including their activities compared with 4D ultrasound, which, however, adds the information of space location. Variances of crown-rump length, nuchal translucency and nasal bone were evaluated. After informed consent and a second opinion of 2 centers performing invasive laser coagulation or occlusion of the umbilical cord, the parents decided to interrupt pregnancy. Pathologic evaluation confirmed MC 5A quintuplet pregnancy. Conclusion: The case demonstrates that splitting of 1 zygote into 5 embryos might even occur spontaneously. In view of the poor outcome and limited success of fetal reduction, pregnancy termination was finally part of the counseling.

研究目的：本研究旨在报告一例自发性单绒毛膜（monochorionic, MC）5羊膜（5-amniotic, 5A）五胎妊娠的产前诊断与病程，此类病例极为罕见，迄今尚无产前相关报道。

病例报告：1例自发性MC 5A五胎妊娠于孕12周经二维超声（2D ultrasound）确诊。采集了二维超声与四维超声（4D ultrasound）录像资料，结果显示，相较于四维超声，二维超声可更清晰地同步显示所有五胎及其活动情况，而四维超声则可补充空间位置相关信息。研究评估了各胎儿的头臀长（crown-rump length）、颈项透明层（nuchal translucency）及鼻骨的差异。在获取知情同意并咨询两家可开展侵入性激光凝固术（invasive laser coagulation）或脐带闭塞术（umbilical cord occlusion）的中心、获取第二诊疗意见后，患者家属最终决定终止妊娠。病理检查证实为MC 5A五胎妊娠。

结论：本病例证实，单个受精卵（zygote）自发分裂为5个胚胎的情况确实可能发生。鉴于胎儿减胎术（fetal reduction）预后不佳且成功率有限，终止妊娠最终成为咨询方案之一。