Figure 23-3 Disappearance curves of serum hCG in three groups of women. Semilogarithmic scale. Upper curve represents women (n=36) who had elective vacuum aspiration abortion at 7-13 weeks LMP. Middle curve represents women (n=35) with spontaneous abortion at 6-15 weeks LMP treated with uterine aspiration. Lower curve represents women (n=35) with ectopic pregnancies diagnosed 2.5-11.0 weeks after LMP and removed surgically.
Source: Steier et al. (1984) 11 with permission.
The initial decrease in beta hCG (hCG) after full-term delivery is quite rapid, so that an hCG level following the delivery will have dropped to less than 50 mIU within 2 weeks, and hCG will be undetectable after 3 to 4 weeks.12 In the case of first-trimester abortion, if hCG is clearing normally from the bloodstream as expected, the hCG level should decline steadily, halving at least every 48 hours. However, initial hCG levels are at the peak at 8 to 10 weeks LMP, as high as 150,000 mIU; therefore even 2 weeks after first-trimester abortion, the hCG levels may still be 1,500 mIU, high enough that all pregnancy tests will still be positive. hCG is likely to be detectable by sensitive tests, including commonly-used office urine test kits, for as long as 60 days after first-trimester abortion.
When patients have medication abortion, beta hCG continues to increase following mifepristone but then declines precipitously after administration of misoprostol. By the first follow-up visit 5-17 days after taking mifepristone, beta hCG levels drop to 20% of the initial value (measured on the day of mifepristone) in 98.5% of successful medication abortions.In contrast to the usual pattern of sharp drop in hCG after medication abortion, it is possible for hCG levels to have a lengthy plateau even though the patient has a clinically normal course without need for surgical intervention. Patients who require surgical intervention less than 15 days after medical abortion due to prolonged bleeding or pain generally have higher absolute and relative beta hCG values than women with normal courses whose beta hCG values drop sharply. However, there is an overlap in absolute and relative beta hCG values between patients with lengthy plateau who in the end have successful medication abortion and those who will require uterine aspiration. Beta hCG measurement is merely a supplement to the general clinical evaluation in determining whether intervention is indicated.
If intrauterine pregnancy continues to evolve after medication or surgical abortion, an upward trend (mean 124% rise, minimum 53% rise in 2 days)10 will be seen in serial quantitative beta hCG values. If an ectopic pregnancy continues to evolve after medication or surgical abortion, beta hCG values can behave erratically; these patterns are discussed in more detail in the section, Managing Problems in Early Pregnancy.
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Key Words: medical abortion, bleeding, cramping, clots, positive pregnancy test, confused, trimester, hCG levels, terminated, delivery, blood, urine, decrease, miscarriage, surgical treatment, ectopic pregnancy, bottom curve, mifepristone, misoprostol
Fjerstad M, Edelman A. Pregnancy testing and assessment of early normal and abnormal pregnancy IN Hatcher RA, Trussell J, Nelson AL, Cates Jr. W, Kowal D, Policar MS. et al Contraceptive Technology 20th edition: page 660, Ardent Media Inc. 2012
Paul M, Stein T. Abortion IN Hatcher Ra, Trussell J, Nelson AL, Cates Jr. W, Kowal D, Policar MS. et al Contraceptive Technology 20th edition: Ardent Media Inc. 2012
Steier et al (1984)