Q&A: Menstrual Blood and Zavah Blood
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Menstrual Blood and Zavah Blood
Question
Hello Rabbi, I wanted to ask whether there is a known physical difference between menstrual blood and zavah blood (that is, if we were to test them medically, for example, would we see different results between the two types of blood)?
If there is indeed a physical difference, why can’t the blood be tested medically and thus help solve cases of halakhic infertility, for example?
Thank you very much
Answer
I am not aware of one
You don’t need a medical difference; it’s enough to calculate the days and know. Google “Niddah of Torah law.”
And see also in the book Kuntrasei Shiurim by Rabbi Yisrael Zev Gustman, tractate Kiddushin, pp. 306-311 (available to subscribers on the Otzar HaChochma website), where he discusses the validity of Rabbi Zeira’s enactment.