PONV must be considered as a side-effect of anesthetics when given to sensitive patients. The patient`s risk of PONV after general anesthesia can best be estimated by a "simplified risk score".

This considers the four major risk factors female gender, non-smoking status, a history of nausea or vomiting after anesthesia and the use of opioids after surgery (Apfel et al, Anesthesiology 1999). If no, one, two, three or four risk factors are present, the risk for nausea and/or vomiting after anesthesia is approximately 10, 20, 40, 60, or 80%. Simply speaking, one risk factor translates to a 20% risk and each additional factor increases the risk by 20%.

This score has been demonstrated to be superior to other, more complex risk scores (Apfel et al. Br J Anaest 2002). One reason might be, that the type of surgery is a rather poor predictor for PONV (Apfel et al. Anaesthesia 2004, in press).

Applying such a risk score as a departmental policy can effectively reduce the overall incidence of PONV in that department (Pierre et al. Can J Anesth 2004).