When Pregnancy Tests Turn Negative


Working a few Peds shifts lately I’ve run into the same question: when should your urine pregnancy test (or quantitative serum hCG) be negative after a regular pregnancy, a termination, or a miscarriage (meaning, could she really already be pregnant again)? I hear different answers depending on the obstetrical consultant I ask, so I decided to do a little literature search myself. It’s really only been looked at in very small studies; I’ve got the specific numbers if you want them, but based on the studies I found, it looks something like this:

After a Full-Term Pregnancy:

  • Should be 3 weeks or less. In some women, ovulation may occur as early as 3 weeks after delivery.

After a Termination with Misoprostol/Mifepristone:

  • In one study, following up at 6-18 days, if the hCG level was 80% lower than the initial hCG level, there was a positive predictive value for successful expulsion of 0.995. There was no information on when the level dropped to 0 or <5.

After a D&C Termination:

  • Depends on the initial hCG, but mean time was 35 days, but could be up to 60 days.

After Miscarriage in Women Who Then Had a D&E for Continued Bleeding:

  • Median ~20 days, range 9-22 days.

After Ectopic with Laparotomy:

  • Ectopics had the lowest hCG to begin with, reached 0 by 1-31 days, median 8.5 days.

References:

  1. Routine terminations of pregnancy—should we screen forgestational trophoblastic neoplasia? The Lancet, 2004.
  2. Human chorionic gonadotropin in maternal plasma after induced abortion, spontaneous abortion, and removed ectopic pregnancy. Obstetrics and Gynecology, 1984.
  3. Verifying the effectiveness of medical abortion; ultrasound versus hCG testing. European Journal of Obstetrics and Gynecology, 2003.
  1. #1 by J. Bartlett - March 20th, 2011 at 22:11

    Had this problem just last week — thanks for this info – would have been handy then, but I’ll have it handy for next time.
    Thanks!

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