Had small and large bowel collapsed in may(from abd scan result) no obstruction colonoscopy normal no cancer still having very narrow stool in pieces, sometime worm shape size, what is the cause ,can collapsed bowel return,take miralax daily?

Bowel collapse is not a medical entity and is an unlikely diagnosis. Shape of the stool is determined mostly by the anus rather than intestine. You may take a fiber laxative like Metamucil and drink enough water daily so that your urine is colorless. For the long term you may try to increase your intake of fiber foods. Wish you good health!

There is no such diagnosis as bowel collapse especially by Scan and with normal colonoscopy. Your diet and fluid intake as well as any ano-rectal pathology such as hemorrhoids, abscess, sphincter spasm, or compression of the rectum from a pelvic mass or uterine pathology can affect the stool caliber. This area is often overlooked during a colonoscopy. See a colorectal surgeon for an office exam.