סימן קנט סעיף ז
כָּל בְּדִיקוֹת אֵלּוּ, בֵּין בְּהֶפְסֵק טָהֳרָה בֵּין בְּשִׁבְעַת יְמֵי נְקִיִים, צְרִיכִין לִהְיוֹת בְּבֶגֶד פִּשָׁתָּן לָבָן אוֹ בְּצֶמֶר גֶפֶן אוֹ בְצֶמֶר לָבָן, נָקִי וָרַךְ, וְתַכְנִסֶנּוּ בְּעֹמֶק לְחוֹרִים וְלִסְדָקִים עַד מְקוֹם שֶׁהַשַּׁמָּשׁ דָּשׁ, וְתִרְאֶה אִם אֵין בּוֹ אֵיזֶה מַרְאֶה אַדְמוּמִית. וְאִם אִי אֶפְשָׁר לָהּ לְהַכְנִיס כָּל כָּךְ בְּעֹמֶק, תִּבְדֹּק עַל כָּל פָּנִים כְּפִי כֹחָהּ הָאֶפְשָׁרִי. וְטוֹב שֶׁלְּכָל הַפָּחוֹת. בְּדִיקָה אַחַת תִּהְיֶה עַד מְקוֹם שֶהַשַּׁמָּשׁ דָּשׁ. (וְצָרִיךְ כָּל אִישׁ לְלַמֵּד אֶת אִשְׁתּוֹ דִּין הַבְּדִיקוֹת, כִּי הַרְבֵּה אֵינָן יוֹדְעוֹת). וּבְתוּלוֹת שֶׁבּוֹדְקוֹת קֹדֶם הַנִּשׂוּאִין, יִבְדְּקוּ גַם כֵּן כְּפִי כֹחָן הָאֶפְשָׁרִי.
All these examinations, whether of the hefsek taharah, or during the seven clean days, must be made with an10Old cloth is softer than new cloth and are more reliable for the examination. If only new cloth is available, she may use it. (Hagaos Maimonee) old white linen cloth, or with a clean, soft, white cotton cloth. She must insert it deeply, and into the crevices, to a depth that the male organ penetrates, and then see if there is any reddish spot on it. If it is impossible for her to insert it to such a depth, she should at least examine herself to the best of her ability.11However, she must check the crevices, as this is essential according to most poskim. If the examination is very painful to her, or if examinations cause her irritations that can make a spot of blood on the cloth, it is sufficient if she makes a hefsek and examines herself once on the first clean day and once on the seventh clean day. (Nodah Beyhudah Tinyana Responsa 129) It is important that at least one12Besides the hefsek taharah. (see Shulchan Aruch 196:6) examination13The best day to choose is the first day. If she did not do this on the first, she should do it on the second, if not, then on the third etc. (Ramah 196:6). (see Chasam Sofer Responsa 178) be made to the depth the male organ penetrates. (It is the duty of every husband to instruct his wife about the laws of examination, for many women are not familiar with them). Virgins who examine themselves before the wedding, should also examine themselves to the best of their ability.
תנא דבי אליהו כל השונה הלכות בכל יום מובטח לו שהוא בן העולם הבא שנאמר הליכות עולם לו אל תקרי הליכות אלא הלכות (נדה ע"ג.)