Background
To determine a true denominator of worldwide surgical need, it is imperative to include estimations at a population-based level, to capture those individuals unable to access surgical care. This study was designed to validate the Surgeons OverSeas Assessment of Surgical need (SOSAS) tool with the addition of a visual physical examination, and describe the prevalence of surgical conditions, deaths possibly averted with access to surgical care, and the number of surgical procedures performed annually, in Nepal.

Methods
The SOSAS tool, developed to measure the prevalence of surgical conditions at a population level and used in two African countries, was employed. Fifteen of the 75 districts of Nepal were chosen proportional to population. Responses were recorded for the head of the household for demographic information and recalled deaths, and two randomly selected household members underwent a verbal head-to-toe interview for surgical conditions and a visual physical examination by a trained physician.

Results
A total of 1350 households were surveyed (2695 respondents). Observed agreement between the verbal response and physical examination findings was 94·6 per cent. Some 10·0 (95 per cent c.i. 8·9 to 11·2) per cent of respondents had a current condition requiring surgical care and 23 per cent of deaths may have been averted with proper access to surgical care. An estimated 291·8 major operations per 100?000 population are performed annually in Nepal.

Conclusion
The visual physical examination component validated the SOSAS tool, and justified the estimates of previous studies in Sierra Leone and Rwanda. These data provide insights into the health needs of Nepal and provide evidence to develop surgical programmes, assist with monitoring and evaluation, and help with advocacy for increased resources in Nepal.