If an appearance of urine on the tip of the penis breaks the wudhu what is the case about a person who wipes himself/herself thoroughly but afterwards finds traces of najasat on the undergarment from the back passage? Also if wetness is found which has come from the back passage does this nullify the wudhu? Are the rulings in this case the same for men and women?
There are two issues; a) Impurity coming out. This invalidates Wudhu, b) Impurity that is already out but not thoroughly washed and leaves stains on the undergarment.
If a person subsequently made Wudhu, the impurity that previously came out does not invalidate the Wudhu. However, if the impurity is equivalent to approximately the hollow of the palm, it will not be permissible to perform Salaat with that garment. If the impurity is lesser than approximately the hollow of the palm, the Salaat will be Makrooh.
If one is unable to remove the impurity which is lesser than the hollow of the palm due to circumstances, then the Salaat will not be Makrooh.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai