סימן קנה סעיף ט
אִשָׁה שֶׁיֵשׁ לָהּ וֶסֶת קָבוּעַ, קֹדֶם שֶׁבָּאָה לָהּ הַשָּׁעָה שֶׁהִיא רְגִילָה לִרְאוֹת, יֵשׁ לָהּ לְהַכְנִיס מוֹךְ דָּחוֹק, לְמַעַן תֵּדַע בְּבֵרוּר, כִּי יֵשׁ לָחוּשׁ, שֶמָּא תֵצֵא מִמֶּנָּה אֵיזוֹ טִפַּת דָּם וְתֹאבַד, וְהִיא לֹא תֵדָע. וְאִם לֹא עָשְׂתָה כֵן, וְעָבַר זְמַן וֶסְתָּהּ, אֲסוּרָה לְבַעְלָהּ, עַד שֶתִּבְדֹּק אֶת עַצְמָהּ הֵיטֵב. וְאִם בְּתוֹךְ הַזְּמָן רָחֲצָה אֶת עַצְמָהּ, שׁוּב לָא מַהֲנֵי לָהּ בְּדִיקָה. וְיֵשׁ לָּהּ לְהַחְמִיר וּלְהַחֲזִיק אֶת עַצְמָהּ טְמֵאָה, כִּי חֲזָקָה הִיא, שֶׁהַדָּם בָּא בִּזְמַנּוֹ הַקָּבוּעַ. אֲבָל אִם אֵין לָהּ וֶסֶת קָבוּעַ, אֶלָּא שֶׁהִיא חוֹשֶׁשֶׁת לְוֶסֶת שֶׁאֵינוֹ קָבוּעַ, אִם עָבַר הַזְּמָן וְלֹא הִרְגִּישָׁה, אַף עַל פִּי שֶׁלֹּא בָדְקָה אֶת עַצְמָהּ, הֲרֵי הִיא אַחַר כָּךְ בְחֶזְקַת טְהוֹרָה. אַךְ עוֹנָה בֵינוֹנִית, שֶׁהִיא יוֹם הַשְּׁלֹשִים, דִּינָהּ כְּמוֹ וֶסֶת קָבוּעַ, וּכְמוֹ שֶׁכָּתַבְתִּי לְעֵיל (סָעִיף ג).
If a woman has a regular fixed period, then before the time arrives when she regularly perceives, she should insert a cloth11The Kitzur Shulchan Aruch rules like the Chavas Da’as who requires such a tampon in place throughout the entire onah. However, this is not the prevailing custom anywhere. The Chazon Ish 80:22 says she has to examine herself [only] one time during that onah. It is better to check once in the beginning and again at the end of the onah. so she will be sure (her menstrual flow has not begun), for otherwise, she must suspect that perhaps a drop of blood issued and disappeared without her being aware of it. If she failed to do so, and the time of her fixed period passed, she is forbidden to her husband12Tiferes L’Moshe prohibits even other intimacies, but the Sidrei Taharah permits it and only forbids marital relations during this time. until she examines herself thoroughly. If during the time of her expected period, she bathed herself, the examination will be of no avail.13Prisha and Placey 184. However, others say that bathing makes no differnce and she is permitted to her husband if she is clean on examination. The Chazon Ish also permits her, and such is the prevailing custom. She must be stringent and consider herself to be in an unclean state, because it is presumed that the flux has come at its regular time. But if she does not have a regular period, but she is being mindful of an irregular period, if the time has passed and she has felt nothing even though she failed to examine herself, she is thereafter presumed to be menstrually clean. However, with regard to the average period, which is the thirtieth day, her status is like that of a regular (fixed) period, as has been stated above.
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.)