Stump appendicitis is a rare delayed complication of appendectomy. The delay in diagnosis is usually because of a prior history of appendectomy. We report a case of stump appendicitis diagnosed pre-operatively with a computerized tomography (CT) scan after laparoscopic appendectomy. An 18-year-old male presented with a one-week history of lower abdominal pain, nausea and vomiting. He had a history of laparoscopic appendectomy for acute appendicitis. Physical examination revealed tenderness and guarding in the lower abdomen. CT scan showed free pelvic fluid with a tubular structure of about 2.5 cm in length and 0.78 cm in diameter located posterior to the ileo-cecal junction. Laparoscopic exploration confirmed the findings. A residual appendiceal stump was found and dissected from the adhesion and removed. Histopathology showed a residual appendix with transmural neutrophilic infiltration associated with multifocal hemorrhagic necrosis. The postoperative period was uneventful. The diagnosis of stump appendicitis can be challenging. CT scan has proven to be a useful tool for the diagnosis of this rare condition.