→Procedure of Milah
# The last stage of milah is metsisah. There is a great controversy whether this is considered a ritual part of the milah procedure or simply a medical practice of the days of the gemara and wouldn't be necessary today. <ref> The Mishna (Shabbat 133a) writes that metsisah is the last stage of milah. The gemara (133b) comments that the reason that is practiced on Shabbat is because if it isn't done there is a critical danger to the baby's life. The Rambam (Milah 2:2) echoes this and says that metsisah is for medical reasons. The Tiferet Yisrael (Boaz Shabbat 19:1) writes that the entire purpose of metsisah is medical and if nowadays it causes a medical danger it doesn't need to be done. See also the Maharam Shik (OC 152) takes the position that there is no danger with metsisah. However, the [http://hebrewbooks.org/pdfpager.aspx?req=1095&pgnum=264 Mishkenot Yacov (YD 63)] writes that drawing blood (hatafat dam) is an integral part of the ritual milah. He proves this from the Zohar and Rashi (Shabbat 134a s.v. lekarchei).</ref> There is a further discussion if metsisah should be done with one's mouth or a utensil. <ref>Har Tzvi (YD 214) writes that since there are dangers with doing metsisah with one's mouth, one may do it with a utensil.</ref> Because of the danger involved, many poskim hold that one should not and may not do metsisah with one's mouth.<ref>Rav Hershel Schachter in a shiur on [http://www.yutorah.org/lectures/lecture.cfm/798611/Rabbi_Hershel_Schachter/Hilchos_Shabbos_3_-_Choleh_BeShabbos_&_Kiddush# yutorah.org ("Hilchos Shabbos 3" min 27-30)] said that there is a real danger to the life of the baby with doing metsisah with one's mouth and it is foolish to continue doing it today. A number of poskim are quoted in an article by David Shabtai and Raymond Sultan entitled Medical Risk Taking in Halacha in 'Journal of Halacha and Contemporary Society, 2006. See also the Binyan Tzion 23 who writes that a mohel who does metsisah must be certain that he is not infected with herpes and cause the baby to become infected. Yalkut Yosef Sova Semachot v. 2 ch. 6 fnt. 1 writes that one may use metzitza bkli such as with a tube if there's a concern of danger, otherwise it is done with one's mouth as the Sdei Chemed (Kuntres Metzitza) writes.
* With respect to the general question of relying on doctors to ascertain that there's no danger see Rav Kook's teshuva about metzitza in Daat Kohen YD 140 who argues that we can never rely on doctors to make such a claim. Yabia Omer OC 7:53 likes this idea.</ref>