Things that may affect the
results of your test include:
Doing a urine test for human chorionic
gonadotropin (hCG) very early in pregnancy (during the first week after
implantation) or on a urine sample taken in the middle of the day. The test may
not always show an early pregnancy.
Miscarriage (spontaneous abortion) or therapeutic abortion. HCG results may remain high
(positive) for up to four weeks after a miscarriage or
Getting an injection of hCG to treat
infertility. This may cause test results to appear high for several days after
Having blood in the urine sample or soap in the
collecting container, which may change the hCG level.
Using heparin, a medicine to prevent blood from
Using some medicines. These include hypnotics (such as Ambien),
antipsychotics, and antinausea medicines (such as prochlorperazine and
promethazine ). Be sure to tell your doctor what medicines you take.
What To Think About
Home pregnancy tests that find hCG in urine are
widely available. For more information, see the topic
Home Pregnancy Tests.
A blood test for hCG
is generally more accurate than a urine test. If pregnancy is suspected even
after urine test results do not show a pregnancy (negative results), a blood
test can be done, or another urine test should be repeated in a
HCG results may remain high (positive) for up to four weeks
after a miscarriage (spontaneous abortion) or therapeutic abortion.
A normal hCG value
does not rule out the possibility of a tumor in the uterus, ovaries, or
testicles. HCG is only one part of an overall evaluation when a tumor is
American College of Obstetricians and Gynecologists
(2007, reaffirmed 2008). Screening for fetal chromosomal abnormalities. ACOG Practice Bulletin
No. 77. Obstetrics and Gynecology, 109(1): 217-227.
Other Works Consulted
Fischbach FT, Dunning MB III, eds. (2009).
Manual of Laboratory and Diagnostic Tests, 8th ed.
Philadelphia: Lippincott Williams and Wilkins.
Pagana KD, Pagana TJ (2010). Mosby?s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
Wapner RJ, et al. (2009). Prenatal diagnosis of congenital disorders. In RK Creasy et al., eds., Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice, 6th ed., pp. 221-274. Philadelphia: Saunders Elsevier.