[Primary lithiasis of the choledochus: etiologic factors and structural characteristics].
OBJECTIVE: To study clinical and morphological characteristics of primary gall stones in the common bile duct in order to establish a differential diagnosis with migrating stones. DESIGN: To analyze a number of clinical parameters (age, parity, evolution, number of stones and diameter), qualitative parameters (sex, obesity, cholecystitis, cholangitis, liver disease or previous biliary surgery) and statistic evaluation. To show composition of stones throw stereomicroscope, electronic microscope and dispersion analysis by X-Ray. PATIENTS: We studied 56 patients who were diagnosed and operated of choledocholithiasis. RESULTS: 21 cases (37.5%) were considered as primary stones (group "a") and 35 (62.5%) were considered as migrating stones (group "b"). We have found significant statistical differences in relationship with the age of patients (p < 0.05) and diameter of stones (p < 0.01). They were both greater in primary stones, while the rest of parameters were not significant. Brown pigment stones dominate in primary stones followed by calcium palmitate and cholesterol stones. We identified bacteria or their traces (38.1%), foreign bodies (19.04%), carbonate of calcium (38.1%) and phosphate of calcium (9.5%). CONCLUSIONS: They are clinical and morphological characteristics which may differentiate between primary and migrating common duct stones. The high incidence of germs or foreign bodies found in the core layer of stones show their importance in the formation of brown pigment.