Yes, ILEOSTOMY is a Scrabble word!

Letter values in Scrabble US: I 1, L 1, E 1, O 1, S 1, T 1, O 1, M 3, Y 4.

Is it a valid word?

ILEOSTOMY is a valid word in the official Scrabble dictionary (US) and the UK Scrabble Dictionary, but not in Words with Friends (ENABLE).

surgical procedure that creates an opening from the ileum through the abdominal wall to function as an anus; performed in cases of cancer of the colon or ulcerative colitis