Fibre-optic sigmoidoscopy compared with the Kato technique in diagnosis and evaluation of the intensity of Schistosoma mansoni infection

450 patients in Riyadh, Saudi Arabia, complaining of chronic abdominal pain and, coming from different countries endemic for schistosomiasis, were examined endoscopically using fibre-optic colono- or sigmoidoscopies, and rectal biopsies were examined for Schistosoma mansoni ova. After a preliminary study showed that more than 6 biopsies did not increase the positivity rate, 6 biopsies were taken from the rectum and examined by the transparency technique. 280 were positive for S. mansoni, 9 of them having in addition 5. haematobium. 4 patients had polyps in the sigmoid colon and rectum. When these positive cases were examined using duplicate 50 mg Kato smears, only 160 (57·1%) were positive. There was a highly positive correlation between the intensity of infection as graded by the 2 techniques. We recommend examination of 6 rectal biopsies using fibre-optic sigmoidoscopy when available in small communities with a patchy distribution of schistosomiasis like Saudi Arabia. The method could also be used to exclude schistosomiasis in persons who have moved from rural to urban or non-endemic areas and are unlikely to be re-exposed to infection. © 1992, Oxford University Press. All rights reserved.