The present studies on gallstones, made by macroscopic morphology and infrared absorption spectra, were carried out in order to clarify recent features of cholelithiasis in rural district. One hundred and sixty-one stones obtained from 152 patients who had cholelithiasis, and who were operated-on at our clinics during the past 10 years, were used for this study.
The average age of the patients was 62 years, and about half of them were over 65 years of age. The patients included 100 women and 52 men. The types and frequency of gallstones are classified as follows: cholesterol stones, 50.9%; pigment stones, 40.4%(black stones, 7.5%; bilirubin stones, 32. 9%) and rare stones, 8.7%. Considerin sexual differences, the frequency of cholesterol stones was nearly 2 times greater in women than in men; on the other hand, that of pigment stones was nearly 2 times higher in men than in women. Regarding the age groups of the patients, although the incidence of cholesterol stones was greater in the group under 64 years of age than in the 65-year-old group, the incidence of bilirubin stones was 4 or more times higher in the latter group than in the former.
From the above observations it is suspected that one of the major reasons for the low incidence of cholesterol stones in rural districts, is because of the high percentage of elderly patients with cholelithasis in these areas. The incidence of black stones was not significantly greater in rural districts.