Colonoscopy is the standard examination for diagnosing colorectal diseases and treating colorectal superficial neoplasms. Colonoscopy must be performed under the best conditions for optimum results. However, it is difficult to lay down rules as there is a scant amount of scientific data or available references on numerous points and because the practice is different from country to country, so that consulting the international literature is of limited use. Most of the options set out below are only the result of consulting experts. These guidelines are provisional and for guidance only as they are liable to change as and when new scientific information comes to light.

SUMMARY We report a case of a 56 year old woman who presented with a long history of chronic attacks of vomiting. On admission to hospital she was cachectic, and attempted parenteral nutrition induced coma. The illness was found to be due to citrullinaemia, a metabolic disorder of the urea cycle. Our patient is the oldest with this disorder so far described in the literature. The main points of the case and its investigation are outlined: hyperammonaemia, amino acid chromatogram, measurement of enzyme activity in skin and liver biopsy material. The therapeutic measures which led to cure are of particular interest.Chronic vomiting in an adult patient without evidence of organic lesions of the gastrointestinal tract or the central nervous system is often considered to be psychogenic.' In children, chronic vomiting is a well known symptom of a metabolic disorder, especially one of urea synthesis leading to hyperammonaemia. Citrullinaemia, a result of an hereditary deficiency of argininosuccinate synthetase, is one of these metabolic diseases. Many cases have been reported in neonates and children, but adult cases are very rare in white people.2 ' We report here the case of an adult female (aged 56 years) with a long history of chronic vomiting traced to citrullinaemia with concomitant bouts of hyperammonaemia. This is the oldest patient so far described. Case reportA 56 year old white woman was referred to our department in October 1980 with cachexia and a long history of chronic cyclic vomiting which had begun in her infancy. There was no past record of such vomiting in her parents and relatives, but her two brothers died shortly after birth of an undetermined cause. The patient's pregnancy and delivery

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1542 Background: Screening for prostate cancer is still in debate. In France, there is no financial barrier for individuals to be screened with the prostate-specific antigen (PSA) test, and there is no recommendation for mass screening. Methods: Two nationwide observational studies were carried out in France. The first one, EDIFICE 1, was conducted in 2005 among a representative sample of 1504 subjects aged between 40 and 75 years and a representative sample of 600 general practitioners (GPs). The second one, EDIFICE 2, was conducted in 2008 with the same methodology. Results: General population: In 2005, 36% of the interviewed male population aged between 50 and 75 years declared having undergone a screening test, compared to 49% in 2008 (OR = 1.63 CI95% 1.25; 2.12). Prostate cancer screening increased in all age groups, however, the most significant increase can be observed in the population aged between 50 and 54 years: 18% in 2005 versus 35% in 2008 (OR = 2.43 CI95% 1.31; 4.52). This trend for increasing testing will probably be confirmed in the future since 57% of males never screened plan to undergo a test, and only 16% of those who did screening plan to stop. The expected participation in the future will be close to 70%. Physicians: In 2005, 58% of GPs systematically recommended prostate cancer screening for their male consultants ages 50 to 74, in 2008 the figure is 65% (OR = 1.32 CI95%1.04; 1.66). For prostate cancer screening, a GP's gender has no significant impact. Systematic recommendation for both breast and colorectal cancer screening has an impact on recommending prostate cancer screening as well; OR = 2.9 (CI95% 2.0–4.4) and OR = 2.0 (CI95% 1.3–3.2) respectively. The GP's age is not associated with a higher rate of systematic recommendation. Conclusions: We have observed in France a significant growth in prostate cancer screening: more persons screened, more often, at a younger age. Despite the lack of consistent evidence, persons and GPs exposed to mass communication and campaign for breast and colorectal cancer screening might infer that screening is valuable for other conditions. No significant financial relationships to disclose.