Blood coming out of one's body

A: Hijamah invalidates Sawm according to the correct opinion maintained by scholars. This is based on the Hadith which reads: A man who cups or gets himself cupped will have their Sawm broken. The same applies to withdrawing a large amount of blood from the fasting person. However, Sawm will continue to be valid if blood is emitted because of a surgical operation. This is because emission of blood in this case is not out of the patient's own will. Q 12: Dentists advise trimming Siwak (tooth-cleansing stick) every twenty four hours to keep its active constituent. Does Sawm become invalid because of using a new Siwak or a new part of it, given the fact that the person may swallow the wicks on the Siwak which break inside the mouth? (Part No. 9; Page No. 203)  A: There is nothing wrong if a fasting person uses the new Siwak or the trimmed one. However, one must spit the wicks that get broken out.