OBJECTIVE To determine the key sonographic features for the diagnosis of sirenomelia in the first trimester of pregnancy. METHODS Cases of sirenomelia from several prenatal diagnosis centers were retrospectively identified and reviewed. The diagnosis was established through the detection of fused lower limbs. Additional sonographic findings were also noted. RESULTS A total of 12 cases were collected. The most striking sonographic finding was the detection of malformed lower limbs, which appeared to be fused and in an atypical position. Nuchal translucency thickness was mildly increased in three cases (25%). An abdominal cyst, representing the dilated blind-ending bowel, was noted in seven cases (58%). Color flow imaging detected a single umbilical artery in six cases (50%) and the associated intra-abdominal vascular anomalies in three cases (25%). No cases of aneuploidy were detected. The pregnancy was terminated in nine cases (75%) and intrauterine demise occurred in the remaining three cases (25%). CONCLUSIONS The sonographic detection of abnormal lower limbs or an intra-abdominal cyst located laterally during the first-trimester scan may be warning signs of sirenomelia. This should prompt a detailed examination of the fetal lower body and intra-abdominal anatomy, including the main abdominal vessels, in order to look for additional confirmatory findings.

中文翻译：

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早孕期超声诊断的肺炎：12例多中心病例并文献复习。

目的确定在妊娠早期诊断出肺炎的关键超声特征。方法回顾性鉴定和审查来自多个产前诊断中心的肺炎线虫病例。通过检测下肢融合来确定诊断。还注意到其他超声检查结果。结果共收集12例。超声检查中最显着的发现是发现下肢畸形，该下肢似乎融合了并且处于非典型位置。3例（25％）的颈部半透明厚度轻微增加。七例（58％）出现腹部囊肿，代表盲肠扩张。彩色血流成像检测到6例（50％）的单条脐动脉和3例（25％）的相关腹腔内血管异常。没有发现非整倍性病例。终止妊娠9例（75％），其余3例（25％）发生宫内死亡。结论在妊娠早期扫描中超声检查下肢异常或腹侧囊肿位于侧面，可能是警报器的警报信号。这应该促使对胎儿下半身和腹内解剖结构，包括主要的腹腔血管进行详细检查，以寻找更多的证实性结果。结论在妊娠早期扫描中超声检查下肢异常或腹侧囊肿位于侧面，可能是警报器的警报信号。这应该促使对胎儿下半身和腹内解剖结构，包括主要的腹腔血管进行详细检查，以寻找更多的证实性结果。结论在妊娠早期扫描中超声检查下肢异常或腹侧囊肿位于侧面，可能是警报器的警报信号。这应该促使对胎儿下半身和腹内解剖结构，包括主要的腹腔血管进行详细检查，以寻找更多的证实性结果。