During our lecture on hormones in pregnancy, the lecturer brought in a few urine samples for us to test using a typical pregnancy test bought at the local pharmacy. One was of a pregnant woman at her fertility clinic, one was from her son, and the third was from her. It was pretty funny. The lecturers used to make students use their own urine samples, but as you can imagine, that sometimes led to some nasty and awkward surprises, so they don’t do that anymore. Here is a nice animation with a clear, simple explanation of how pregnancy tests work. If you’re more a static-visual person, this diagram of a pregnancy test is a nice representation, too.
The history of pregnancy tests is pretty interesting, from using wheat and barley as a substrate for pregnant women’s urine, to mixing urine with wine, to the really upsetting practice of sacrificing animals and dissecting their ovaries to determine if human hCG was present.
Just as important as testing for pregnancy is using protective methods to prevent fertilization in the first place. The ARHP’s page on different forms of contraceptive methods is super-helpful. Part of my gripe about needing better sex ed is that I didn’t know about ANY of these methods before medical school beyond “the pill,” which now I see was really only oral estrogen-progesterone formulations in the mass market.
The “Yuzpe method” is a regimen for emergency contraception developed in 1977. It consists of 2 doses of 100 ug ethinyl estradiol and 0.5 mg levonorgestrel taken 12 hours apart. Although there are a variety of pills formulated in this manner, it is possible to achieve this dose with 8 low-dose OCPs taken at the same time.
It must be done less than 72 hours after unprotected intercourse. It results in a 75% reduction in pregnancy, and common side effects include nausea and vomiting (sometimes patients are given a prescription for meclizine along with the pills).
Caveat: if a woman doesn’t bleed within 4 weeks of taking emergency contraception, she should be tested for pregnancy.
The Yuzpe method is NOT the same as Plan B, which is levonorgestrel alone (and has a higher efficacy rate). Plan B and the copper IUD are the two most effective forms of emergency contraception.