Complicated diverticulitis includes diverticulitis associated with uncontained, free perforation with systemic inflammatory response, fistula, abscess, stricture, or obstruction
Uncomplicated diverticulitis is diverticulitis not meeting the above definition, and includes microperforation with small amounts of contained, extraluminal gas without systemic inflammatory response
The American Society of Colon and Rectal Surgeons Clinical Practice Guidelines for the Treatment of Left-Sided Colonic Diverticulitis. Dis Colon Rectum. 2020;63:728–747. doi: 10.1097/DCR.0000000000001679