Faculty of Medicine, University of Ottawa, Ottawa, ON.
Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON.
J Obstet Gynaecol Can. 2020 Sep;42(9):1151-1153. doi: 10.1016/j.jogc.2019.11.070. Epub 2020 Jan 29.
Rh immunoglobulin (RhIg) is usually detectable a maximum of 12 to 14 weeks after administration. Positive antibodies beyond this time frame suggests alloimmunization.
A woman had three pregnancies over a 6-month period, with two first-trimester losses. She received RhIg in the first pregnancy but not in the second. Two months after the second loss, in her third pregnancy, she received RhIg at week 6 due to first-trimester bleeding. She was subsequently anti-D antibody positive up to week 28 with antibodies too low to titre, leading to confusion about whether alloimmunization had occurred.
Rh Ig administration led to positive anti-D antibodies lasting 22 weeks, suggesting keeping this differential diagnosis in mind when suspecting alloimmunization with positive antibodies at levels too low to titre.
Rh 免疫球蛋白（RhIg）通常在给药后最多 12 至 14 周内可检测到。在此时间框架之外出现阳性抗体提示同种免疫。
一名妇女在 6 个月的时间内怀孕了 3 次，其中 2 次发生了早期流产。她在第一次妊娠中接受了 RhIg，但在第二次妊娠中没有接受。第二次流产后两个月，在第三次妊娠中，由于早期出血，她在第 6 周接受了 RhIg。随后，她的抗-D 抗体在第 28 周前呈阳性，但抗体滴度太低，导致对是否发生同种免疫产生了混淆。
Rh Ig 的给药导致了持续 22 周的阳性抗-D 抗体，这表明在怀疑抗体滴度太低而发生同种免疫时，应牢记这种鉴别诊断。
