Summary

Diverticular disease is very common and may cause symptoms of psoas irritation because of contiguous inflammation arising from the colon affecting the retroperitoneum. Retroperitoneal perforation is rare and is marked by free gas in the adjacent musculature. Rarely infection and associated gas may track into the lower limbs; however, if adequate drainage can be achieved, surgery in the unfit may be avoided. We present a case of a 79-year-old woman with retroperitoneal perforation of diverticular disease presenting with free gas in the leg musculature that was managed conservatively because of associated comorbidities and was associated with the formation of a cutaneous faecal fistula in the lower limb.