Fluctuating hCG Levels

I got pregnant with the first cycle of shots and IUI, but the hCG reports have me very concerned. On Day 28, my hCG level was 134, but on Day 30 it was only 184. Over the next two weeks it slowly rose to 740. Today, six weeks from the first day of my last period, my hCG level is suddenly 4289. My ultrasound is not scheduled for two more weeks. Have you ever heard of such fluctuating hCG levels and can this be a normal pregnancy?


Peg Plumbo CNM

Peg Plumbo has been a certified nurse-midwife (CNM) since 1976. She has assisted at over 1,000 births and currently teaches in the... Read more

Such fluctuations in hCG level could possibly indicate an ectopic pregnancy, or perhaps loss of a pregnancy and then a subsequent conception. Of course there could always have been a lab error in one of the tests.

As a rule, the (beta) hCG concentration doubles about every one to three days during a normal pregnancy, depending on the gestational age at the time the hormone is measured. In contrast, two-thirds of ectopic pregnancies have a (beta) hCG concentration that doubles at a slower rate, plateaus, or falls.

The range of values at a single point in time varies. In some studies the value ranges from 1000 to 10,000 mIU per milliliter four weeks after conception (six weeks after the last menstrual period). A single value is therefore not diagnostic. The variation in (beta) hCG values is due in part to uncertainty about the time of conception, but even when it is known, as in in in vitro fertilization cycles, some variation in values remains.

hCG levels in conjunction with ultrasound are more helpful. The discriminatory zone is the level of (beta) hCG associated with ultrasonographic evidence of an intrauterine sac in a woman with a normal intrauterine pregnancy. With conventional abdominal ultrasonography, the discriminatory zone is 6500 mIU per milliliter. On the other hand, with vaginal ultrasonography, which increases the resolution because of the closer proximity to the involved tissue, the level drops to 2800 mIU per milliliter. Incorporating the doubling time of the (beta) hCG level into the formula allows one to diagnose ectopic pregnancies approximately four days earlier than when relying on ultrasonographic findings alone. A secondary benefit of vaginal ultrasonography is that with a (beta) hCG level of 1000 mIU per milliliter, 50 percent of intrauterine sacs will be seen, allowing the clinician to rule out an ectopic pregnancy earlier in some patients.

I would be inclined to ask for an ultrasound at an earlier date. Due to differences in laboratory norms, it would be impossible for me to comment upon the potential for viability of this pregnancy. I would still maintain hope for a pregnancy with a hCG level of 4300 but the slow increase is a cause for concern. I think an ultrasound is warranted.

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