What is the ruling on a doctor seeing or touching a patient's 'awrah for examination, and working in an environment full of blood and urine, and is ablution (wudu') required to be repeated in these cases?

It is permissible for a doctor to touch and look at a man's 'awrah for treatment, as well as to touch blood in a wound out of necessity. He should then wash his hand. Wudu' is not nullified by touching blood or urine, but it is nullified by touching the 'awrah (the front or back private parts) without a barrier, according to the Prophet's (peace be upon him) saying: "Whoever touches his private parts with his hand without a barrier between them, wudu' becomes obligatory upon him." This ruling also applies to a female doctor if she touches a woman's private parts out of necessity.