Obstet Gynecol. 2019 Mar;133(3):589-591. doi: 10.1097/AOG.0000000000003101.
Obstetricians frequently diagnose thrombocytopenia in pregnant women because platelet counts are included with automated complete blood cell counts obtained during routine prenatal screening (1). Although most U.S. health care providers are trained using U.S. Conventional Units, most scientists, journals, and countries use Système International (SI) units. The laboratory results reported in U.S. Conventional Units can be converted to SI Units or vice versa by using a conversion factor. Given the conversion factor is 1.0, when converting from 10/μL to 10/L the platelet "count" does not seemingly change. Thrombocytopenia, defined as a platelet count of less than 150 x 10/L, is common and occurs in 7-12% of pregnancies at the time of delivery (2, 3). Thrombocytopenia can result from a variety of physiologic or pathologic conditions, several of which are unique to pregnancy. Some causes of thrombocytopenia are serious medical disorders that have the potential for maternal and fetal morbidity. In contrast, other conditions, such as gestational thrombocytopenia, are benign and pose no maternal or fetal risks. Because of the increased recognition of maternal and fetal thrombocytopenia, there are numerous controversies about obstetric management of this condition. Clinicians must weigh the risks of maternal and fetal bleeding complications against the costs and morbidity of diagnostic tests and invasive interventions. This Practice Bulletin is a targeted revision to reflect limited changes to information about new estimates for thrombocytopenia in pregnancy and the risk of recurrence of fetal-neonatal alloimmune thrombocytopenia in subsequent pregnancies, and to provide new information on the level of thrombocytopenia that permits regional anesthesia.
产科医生经常在孕妇中诊断出血小板减少症，因为血小板计数包含在常规产前筛查中获得的自动全血细胞计数中 (1)。尽管大多数美国医疗保健提供者都接受过使用美国常规单位的培训，但大多数科学家、期刊和国家都使用国际单位制 (SI) 单位。美国常规单位报告的实验室结果可以通过使用转换因子转换为 SI 单位或反之亦然。由于转换因子为 1.0，因此从 10/μL 转换为 10/L 时，血小板“计数”似乎不会改变。血小板减少症定义为血小板计数小于 150 x 10/L，在分娩时常见，发生率为 7-12% (2,3)。血小板减少症可由多种生理或病理状况引起，其中一些是妊娠特有的。一些血小板减少症的原因是严重的医学疾病，可能对母婴造成发病率。相比之下，其他情况，如妊娠性血小板减少症，是良性的，不会对母婴造成风险。由于对母亲和胎儿血小板减少症的认识增加，关于这种情况的产科管理存在许多争议。临床医生必须权衡母婴出血并发症的风险与诊断测试和侵入性干预的成本和发病率。本实践公告是一次有针对性的修订，以反映有关妊娠血小板减少症新估计值和随后妊娠胎儿-新生儿同种免疫性血小板减少症复发风险的信息的有限变化，并提供关于允许区域麻醉的血小板减少症水平的新信息。
