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. Author manuscript; available in PMC: 2021 Jul 1.
Published in final edited form as: Contraception. 2020 Mar 3;102(1):1–6. doi: 10.1016/j.contraception.2020.02.011

Figure 4. In vivo concentrations of fetal red blood cells and maternal F cells.

Figure 4.

(a) fetal RBC number and (b) maternal F cell number per 10 million RBCs pre- vs. post-procedure in subjects undergoing first trimester uterine aspiration (n=37). Each line represents an individual subject. (c) Number of fetal RBCs (red) and maternal F cells (black) per 10 million in post-procedure samples (one mark of each color per subject). The lower dotted line is the calculated threshold for sensitization (250 fetal RBCs per 10 million total RBCs). The upper dotted line is the threshold for detection by the Kleihauer-Betke assay (4,000 fetal RBCs and/or maternal F cells per 10 million total RBCs). fRBC = fetal red blood cell. GA = gestational age. K-B = Kleihauer-Betke. MFC = maternal F cell.