Hopefully this is last question from me on this for a long time. (I apologize if these kinds of questions are getting excessive)
Is it okay to hold when not wanting to miss out on something like a lecture or for some other non medical reason? I read somewhere about the 72 minutes rule if one can hold and not have needing to go to the bathroom preoccupy the mind but be able to focus on something else and it will not fall under Bal tishaktzu.
I am assuming the previous answer about it being okay for medical reasons also apply to holding to have enough to give a urine sample or for an ultrasound or other medical reasons.
If the person already reached Baal tishaktzu it is incorrect, to hold it in for non medical reason, or if it isn’t going to cause him public embarrassment.
The idea that if a person can wait from going to the bathroom 72 minutes that he may learn or say a bracha, is only until it will become baal tishaktzu.
It is considered baal tishaktzu when the person has to hold himself back from not reliving himself (Shilchan Aruch Horav).
Giving a urine sample or for an ultrasound are considered medical reasons.