The Discrepancy between Gross Features and Chemical Compositions in Gallbladder Stone: A Descriptive Single Center Study in the United Arab Emirates

Background and Study Aim: Gallbladder stone (GBS) is a common gastrointestinal disease that is the primary indication for cholecystectomy. The present study was conducted to describe the chemical composition of gallstones in a tertiary referral hospital in the United Arab Emirates. Materials and Methods: Patients diagnosed with GBS and who underwent cholecystectomy due to symptomatic GBS and cholecystitis in Sheikh Khalifa Specialty Hospital were enrolled in this study. After cholecystectomy, all stone specimens were classified according to their gross findings into 4 groups, namely black pigmented stones (BLPS), brown pigmented stones (BRPS), mixed cholesterol stones, and cholesterol stones (CLS). Quantitative analysis using Fourier transform infrared spectroscopy was then performed to define the stones' chemical constituents. They were reclassified into two groups as CLS (cholesterol ≥ 60%) and pigmented stones (PGS, cholesterol ≤ 59%) based on gallstone composition analysis. Results: A total of 237 stones were divided into four groups based on their gross findings; cholesterol stones (32.0%), mixed cholesterol (29.2%), black pigmented (26.4%), and brown pigmented (12.3%). After chemical composition analysis, they were resorted into the two following groups according to their cholesterol proportions: pigmented (28.3%) and cholesterol (71.7%). There were significant statistical mean age differences between the pigmented and cholesterol stone groups (58.5±19.8 vs. 34.4±11.0, p < 0.01). Conclusion: This descriptive study showed the hospital-based clinical incidence of GBS and suggested that there might be a discrepancy in stone classification based on gross findings and chemical compositions. Moreover, pigmented stones are more likely to be present in older patients than cholesterol stones.