If one began praying when she had no need to relieve herself but a great need arose in the middle of her prayer, since she began praying in a permitted state, she may continue her prayer for as long as she can hold it in. Even if she knew ahead of time that she needs the bathroom, but she thought she could hold it in for 72 minutes, but when she started praying she suddenly felt that she could no longer control herself for 72 minutes, although le-khatĥila she should have relieved herself before praying, since she began praying with the thought that she would be able to wait, she may finish praying.
If her need to relieve herself is so urgent that she cannot wait any longer, she should go immediately. If the interruption in her prayer lasts long enough that in that time she could have prayed the full Amida prayer from beginning to end, she must start the Amida again. But if the interruption lasts less time, she continues from the berakha at which she stopped. 1
- A woman who recites the entire prayer service and started to pray when she did not need to relieve herself, yet suddenly feels that she cannot wait 72 minutes, but still does not need to urgently hold it in to suppress the need to relieve herself, and if, when she goes, she will have to exert herself slightly to relieve herself: since she began praying in a permitted fashin, and her need is slight, she may complete the section she is reciting. If the need arises in the middle of Pesukei De-zimra, she waits until she finishes all of Pesukei De-zimra by saying Yishtabaĥ, and then goes to relieve herself. If the need arises during the recitation of Birkhot Keri’at Shema, she relieves herself at the end of the berakha or passage she is reciting (MB 92:9; BHL s. v. “Ya’amid”; Peninei Halakha: Prayer, ch. 5 n. 10).
If her sudden need is so pressing that she must actively suppress it to prevent herself from urinating or defecating, at which point she transgresses “bal teshaktzu” (Rema 92:2, based on SAH 3:11), the law is as follows: If she is in the middle of Pesukei De-zimra or Birkhot Keri’at Shema, since interruption at that point is not so serious, she must go immediately to relieve herself. However, if she is in the middle of the Amida, where a pause at that point is serious, and if, when she began reciting the Amida, she did not feel the need to relieve herself, she should finish praying. If she cannot wait at all, should she go relieve herself (Peninei Halakha: Prayer, ch. 5 n. 11). ↩