Anatomical classification of acute complicated diverticulitis (Hinchey 1978).

What it is and when to use it

The Hinchey classification stages the severity of acute complicated colonic diverticulitis, particularly of the sigmoid, based on the surgical or CT finding of the extent of inflammation, abscess, and peritonitis. It is used to guide the therapeutic decision between conservative management, percutaneous drainage, and emergency surgery. The modified version (Wasvary/Kaiser) incorporates CT findings and is the reference used by society guidelines such as the ASCRS (American Society of Colon and Rectal Surgeons) and the WSES.

How to interpret it

Stage I: pericolic inflammation or phlegmon (Ia) or a confined pericolic abscess (Ib); usually managed medically, with percutaneous drainage if the abscess is large. Stage II: distant pelvic, intra-abdominal, or retroperitoneal abscess; often a candidate for image-guided percutaneous drainage plus antibiotics. Stage III: generalized purulent peritonitis from rupture of an abscess without free communication with the bowel lumen; requires emergency surgery. Stage IV: feculent peritonitis from free perforation with fecal contamination; emergency surgery, carrying the highest mortality. In general, the higher the stage, the greater the likelihood of surgical intervention and the worse the prognosis.

Limitations and when not to use it

It was designed and validated for acute colonic diverticulitis, originally as an intraoperative classification and later adapted to CT. It does not apply to uncomplicated diverticulitis and is not used to decide outpatient discharge; it does not assess systemic sepsis, comorbidity, or anesthetic risk, so the surgical decision must be individualized against the overall clinical status. A frequent misuse is staging on imaging alone without clinical correlation, or applying it to recurrent/chronic episodes, for which it is not intended.

Frequently asked questions

What is the difference between Hinchey I and II?

Stage I is a confined pericolic abscess or phlegmon near the colon, whereas stage II is a distant abscess (pelvic, intra-abdominal, or retroperitoneal). Stage II usually requires percutaneous drainage, unlike a small stage I, which is often treated with antibiotics alone.

Which Hinchey stages require emergency surgery?

Stages III (generalized purulent peritonitis) and IV (feculent peritonitis) require emergency surgery. Stages I and II are usually managed with antibiotics and, when needed, percutaneous drainage.

Is the Hinchey classification based on CT or on surgery?

The original Hinchey classification (1978) was an intraoperative classification. The modified Wasvary/Kaiser version incorporates CT findings and is the one currently used in clinical practice.