A woman who is a Nidda must observe a seven-day period called "Shib’a Nekiyim" ("seven clean days") before she can immerse in a Mikveh. Each day during this seven-day period, she must perform two inspections to ensure the absence of blood. She performs one inspection upon awakening in the morning, and a second inspection before sundown. In total, then, a woman must perform fourteen inspections during the period of Shib’a Nekiyim.
These Bedikot (inspections) are in addition to the two inspections performed the day before the Shib’a Nekiyim. Before beginning the Shib’a Nekiyim, the woman must ensure the cessation of bleeding by performing an inspection called the "Hefsek Tahara." After this inspection, before sundown, she must then insert a cloth and leave it there for approximately thirty-five minutes, at which point she removes it and checks it for blood. This second inspection is called the "Moch Dahuk." These two inspections do not count toward the fourteen inspections that are required during the Shib’a Nekiyim. In all, then, a woman must perform at least sixteen inspections during the process of becoming Tehora (pure).
If a woman did not, for whatever reason, perform the required Bedikot during the Shib’a Nekiyim, she may nevertheless immerse at the conclusion of this period, provided that she performed at least one inspection on the first day, and at least one on the seventh day. Although she must make two inspections each day, as discussed, she is nevertheless eligible to immerse and become Tehora after the Shib’a Nekiyim if she performed at least one Bedika on the first day and one on the seventh.
If a woman did not make an inspection on the first day, she may count the Moch Dahuk inspection as the inspection for the first day. Since the Moch Dahuk remains in place until after nightfall, it may be considered as having taken place on the first day of the Shib’a Nekiyim. Of course, a woman should not rely on the Moch Dahuk as her inspection for the first day; she must perform two inspections on the first day even though she performed the Moch Dahuk inspection. However, if she forgot to inspect on the first day, then she may rely on the Moch Dahuk inspection, and thus count that day as the first day of her Shib’a Nekiyim despite the fact that she did not perform any inspections during the day. In any case, a Rabbi should be consulted.
It should be noted that this applies only to the Moch Dahuk inspection, and not to the Hefsek Tahara inspection. The Hefsek Tahara is performed before sundown on the day before the Shib’a Nekiyim, and it therefore cannot count as an inspection for the first day of the Shib’a Nekiyim under any circumstances.
Summary: A woman must perform two Bedikot (inspections) on each day of the seven-day Shib’a Nekiyim period which she observes after the cessation of menstrual bleeding. Nevertheless, she may immerse in the Mikveh even if she does not perform these inspections, provided that she performed at least one inspection on the first day and one on the seventh day. These fourteen inspections are required in addition to the Hefsek Tahara and Moch Dahuk inspections performed before the Shib’a Nekiyim. However, if a woman did not perform any inspections on the first day of the Shib’a Nekiyim, then she may rely on the Moch Dahuk inspection which she performed the previous night, and consider that as her first day’s inspection. In any event, a Rabbi should be consulted.
