A review. For selected patients meeting their inclusion criteria, NOTA seems to work in the short-term for 90% of patients, but fails in the medium term in a quarter (1 yr) and in the long-term in nearly a half (5 years). Patients in whom NOTA fails in hospital are much more likely to have complicated appendicitis, but overall there do not seem to be any clear differences in outcome other than a probable reduction in pain for patients not undergoing surgery. There is also a small but important risk of missing an underlying malignancy in 0.5% of patients.