K59.3Megacolon, not elsewhere classified

K59.3 is the ICD-10-CM diagnosis code for megacolon, not elsewhere classified. It belongs to category K59 (other functional intestinal disorders), block K55-K64 (other diseases of intestines) and chapter 11 (diseases of the digestive system). It is a header code, so it can't be reported by itself; one of its 2 subcodes must be used instead.

Within K59 (other functional intestinal disorders), K59.3 is specifically for megacolon, not elsewhere classified. Related codes cover constipation (K59.0), functional diarrhea (K59.1), neurogenic bowel, not elsewhere classified (K59.2), anal spasm (K59.4), other specified functional intestinal disorders (K59.8) and functional intestinal disorder, unspecified (K59.9).

To report this condition, pick the subcode that matches the documentation: K59.31 (megacolon) and K59.39 (megacolon).

Don't report K59.3 together with the conditions in its Excludes1 note: congenital megacolon (aganglionic) (Q43.1), megacolon (due to) (in) Chagas' disease (B57.32), megacolon (due to) (in) Clostridium difficile (A04.7-) and megacolon (due to) (in) Hirschsprung's disease (Q43.1).

Code first: , if applicable (T51-T65) to identify toxic agent.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015, and changed in FY2017 (expanded into subcodes).