A pregnant patient on anticonvulsant therapy presents a positive home pregnancy test; which factor is most likely responsible for this false-positive result?

• A. Irregular menstrual cycle
• B. Using an anticonvulsant for epilepsy
• C. Taking the pregnancy test too early
• D. Being under too much stress at work

Answer: (B)

The key idea is how home pregnancy tests work and how they can be disrupted. Home tests detect hCG in urine using antibodies. Sometimes substances in the urine or immune factors introduced by certain medications can interfere with that antibody reaction and produce a positive result even when pregnancy isn’t present. Anticonvulsants used for epilepsy can, in rare cases, affect immune responses or lead to cross-reactive antibodies that interfere with the assay, increasing the chance of a false-positive test. Because of this potential interference, a positive home test in a patient taking anticonvulsants should be confirmed with a serum quantitative hCG test and, if needed, a different assay or clinical assessment to verify pregnancy.