Does inserting a catheter into the patient’s body to drain urine invalidate the fast?

Praise
be to Allah

Inserting a catheter into the patient’s body to drain urine
and waste from his stomach does not invalidate the fast, because that does
not come under the heading of food or drink, and it is not akin to food or
drink. 

Shaykh Ibn ‘Uthaymeen (may Allah have mercy on him) said: 

The Lawgiver has only forbidden us to eat or drink – i.e.,
during the fast – so whatever takes the place of food or drink comes under
the same ruling as food and drink, and whatever is not like that and does
not come under the heading of food or drink in terms of wording or meaning,
the ruling on food and drink cannot be applied to it. 

End quote from Majmoo‘ Fataawa wa Rasaa’il al-‘Uthaymeen
(19/205) 

He also said: 

If a person inserts a scope into the stomach until it reaches
it, then that breaks the fast – i.e., according to our madhhab. 

But the correct view is that it does not break the fast,
unless there is some oil or the like on this scope that reaches the stomach
by means of this scope, in which case it does break the fast, and it is not
permissible to use it during an obligatory fast except in cases of
necessity. 

If a person had an opening in his stomach, and something
entered his stomach through this opening, then according to our madhhab his
fast would be broken thereby, just as it would be broken by a deep stab
wound. 

But the correct view is that the fast is not broken thereby,
unless this opening is made in place of the mouth, so that food and drink
enter through it, in cases of oesophageal blockage, ulcers and the like, in
which case whatever enters through it breaks the fast, just as if it entered
through the mouth. This is the view favoured by Shaykh al-Islam Ibn Taymiyah.
End quote from ash-Sharh al-Mumti‘ (6/370).

Shaykh Sulaymaan al-Maajid (may Allah preserve him) said: 

Catheterisation means inserting a tube into the urethra for
various medical purposes. It does not break the fast of one who is fasting,
because it is not food or drink, and does not come under the heading of
other things that break the fast. End quote. 

http://www.salmajed.com/node/12191

See also the answers to questions no.
38023 and 2299 

And Allah knows best.