Résumé : We report the case of a 54-year-old man, without particular pathological antecedents admitted to the emergency of the university hospital of Monastir, for right renal colic. Radiography of the urinary tract without preparation and renal echography showed bilateral renal lithiasis and a right ureteral lithiasis. The interrogation revealed concept of vomiting after which the patient felt relieved. The biological assessment objectified an hypochloremic metabolic alcalosis, an increase in the anion gap, a severe impaired renal function of obstructive origin and an hypokaliemia. The presence of the lithiasis did not explain on its own the metabolic disorders of this patient. The other investigations showed that initial pathology was an evolutionary bulb ulcer into pre-stenosis justifying treatment by omeprazole and explaining the biological disorders.