Vaginal bleeding is not uncommon in the first trimester of pregnancy. Ultrasound is the foremost modality for evaluating normal development of the gestational sac and embryo and for discriminating the causes of bleeding. While correlation with quantitative βHCG and clinical presentation is essential, sonographic criteria permit diagnosis of failed pregnancies, ectopic pregnancy, gestational trophoblastic disease and spontaneous abortion. The American College of Radiology Appropriateness Criteria guidelines have been updated to incorporate recent data. A failed pregnancy may be diagnosed when there is absence of cardiac activity in an embryo exceeding 7 mm in crown rump length or absence of an embryo when the mean sac diameter exceeds 25 mm. In a stable patient with no intrauterine pregnancy and normal adnexae, close monitoring is advised. The diagnosis of ectopic pregnancy should be based on positive findings rather than on the absence of an intrauterine sac above a threshold level of βHCG. Following abortion, ultrasound can discriminate retained products of conception from clot and arteriovenous fistulae. The American College of Radiology Appropriateness Criteria® are evidence-based guidelines for specific clinical conditions that are reviewed every two years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.

译文

妊娠前三个月阴道出血并不少见。超声是评估孕囊和胚胎正常发育以及区分出血原因的最重要方法。尽管与定量 β hcg和临床表现的相关性至关重要,但超声检查标准允许诊断失败的妊娠,异位妊娠,妊娠滋养细胞疾病和自然流产。美国放射学学院的适当性标准指南已更新,以纳入最新数据。当胚胎中没有超过冠臀部长度7毫米的心脏活动或当平均囊直径超过25毫米时没有胚胎时,可以诊断出失败的妊娠。对于没有宫内妊娠且附件正常的稳定患者,建议密切监测。异位妊娠的诊断应基于阳性发现,而不是没有超过 β hcg阈值水平的宫内囊。流产后,超声可以将保留的受孕产物与凝块和动静脉瘘区分开。美国放射学学院适当性标准®是针对特定临床状况的循证指南,由多学科专家小组每两年审查一次。指南的制定和审查包括对来自同行评审期刊的当前医学文献的广泛分析,并应用完善的共识方法 (修改的Delphi) 来评估小组对成像和治疗程序的适当性。在缺乏证据或不确定证据的情况下,可以使用专家意见来建议成像或治疗。

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