Bleeding from a Pap smear is from the cervix, not the uterus, and does not make you niddah.

Regarding the bleeding from the endometrial biopsy, there are three separate halachic questions:

1) Did this bleeding meet the usual criteria for niddah, or was it the type of staining that does not make you niddah?

2) What is the status of bleeding from an injury inside the uterus?

3) What was the size of the instrument that entered the uterus?

Regarding question 1: If the bleeding was light and you didn’t feel a hargashah, and you saw it only on colored underwear or disposable pads, or even spots of less than a k’gris (about the size of a US dime or Israeli shekel) on white underwear, you are definitely not niddah. If you are Ashkenazi and saw blood on toilet paper after wiping within a few seconds of urinating, you could be niddah. These halachot are discussed in detail in our articles on Stains and Toilet Paper.

Regarding question 2: An endometrial biopsy generally causes uterine bleeding. Halachic authorities differ on the question of whether uterine bleeding caused by injury makes a woman niddah.

Rav Yehuda Henkin, the posek of this site, rules that such bleeding does not make you niddah. Bleeding from an endometrial biopsy can go on for about a week, and for that time can be attributed to the procedure.

Some rabbis are less comfortable permitting bleeding that comes from the uterus, even if a clear source of injury is seen. Even according to those authorities, the bleeding would make you niddah only if it meets the criteria outlined in question 1.

Regarding question 3: For all procedures that enter the uterus, the size of the instrument that enters is also important. Instruments larger than a certain size render a woman niddah even if there is no bleeding. Opinions as to this size vary – Rav Henkin rules that an instrument with a diameter of 19mm or more would make a woman niddah. A pipelle is a very narrow instrument that would not make you niddah.

To summarize: According to Rav Henkin, you are definitely not niddah. If your rabbi is strict regarding bleeding from an injury inside the uterus, your status depends on the nature of the bleeding and where it was seen.

Please write back with any further questions.

This response has been updated to reflect the rulings of our current Rabbinic Supervisor, Rav Kenneth Auman, regarding waiting before wiping.