2,108. Unusually-Shaped Stains on Skin
Hilchos Issurei Biah 9:9
If a blood stain found on a woman’s skin is long like a thread, round or made up of multiple small drops, if the stain runs horizontally across her thigh, of if it looks like the stain was made from the bottom going up, she is nevertheless rendered unclean since the stain is opposite her genitals. We don’t say that had the stain dripped from her it wouldn’t have taken such a shape. Rather, we act stringently when it comes to any blood found in this area even if there’s reason to doubt it.
Hilchos Issurei Biah 9:10
A stain found on a woman’s garment below the belt renders her ritually unclean; above the belt, she remains ritually clean. If the stain is found on her sleeve, then if it can reach her genitals, she is rendered unclean; if not, she remains clean.