Testing for pregnancy is possible with the available home pregnancy tests. These tests work by checking for the pregnancy hormone called human chorionic gonadotropin (hCG) in a urine sample.
Different factors can cause false-negative results, such as carrying out the test too early, misusing the test, testing with diluted urine and using an expired test. On the other hand, some medications can interfere with the test to give a false negative, making you think you are pregnant when pregnancy has not occurred.
Some medications administered during intrauterine insemination (IUI) or in vitro fertilisation (IVF) can interfere with the hCG measurements since they are variants of hCG.
Women who cannot ovulate on their own get a prescription for a fertility medication known as Clomid (clomiphene citrate). After taking the medication for five days, the women will receive a trigger shot of Novarel, Ovidrel or Pregnylto induce ovulation and mature eggs.
Usually, the synthetic hCG from the trigger shots remain in the body for about ten days before clearing, so taking a pregnancy test soon after receiving the trigger shot will likely give you a false-positive result.
When taking these fertility medications, ensure you wait for at least two weeks before getting a pregnancy test. This ensures that the synthetic hCG has cleared from your body. Most private obstetrician in London do not recommend home pregnancy testing after fertility treatment but advise patients to visit the clinic for a blood test. Although the blood test also detects hCG, it is more accurate than the home testing, that a urine sample.
Human menopausal gonadotropin (hMG) is another injectable drug for triggering ovulation. HMG contains two hormones: follicle-stimulating hormone (FSH) and luteinising hormone (LH). The common hMG medication includes Repronex, Pergonal and Menopur.
When this medication is used for IUI or IVF, the LH can trigger a false-positive test result, but for different reasons. Unlike the hCG medication, which triggers a false positive due to synthetic hormones, the LH surge can cause a false positive result because the two hormones have a similar structure.
If you carried out a pregnancy test and think the negative result is wrong, you can wait for about two days then carry out another test. Most times, when you test too early, the result will show negative because the hCG level is below the detectable level for the home pregnancy test.
HCG levels will usually be double every two days when you are pregnant. If you get the pregnancy test after two days when your hCG levels have doubled again, the chances of having an accurate result increase.
However, if you are undergoing IUI or IVF, ensure you follow your doctor’s advice and wait to get a blood hCG test at the doctor’s office. Although waiting two weeks before getting the test may leave you anxious, you reduce the risk of having a false-positive result that may be more upsetting.
If you are concerned about a false-positive result and need a private gynaecology clinic in London to confirm the result, visit Medical Express Clinic or call 020 7499 1991 to book an appointment.