The patient had not previously undergone abdominal surgery and had no chronic diseases. Physical examination revealed local rebound tenderness over the ileocecal region, a temperature of 38°C, a heart rate ABSTRACT Introduction: Acute abdominal pain in the lower-right quadrant can be misdiagnosed as acute appendicitis and may be caused by anatomic variations of the intra-abdominal organs in rare cases. Anatomical variations in the position and morphology of the sigmoid colon should be considered by clinicians and radiologists to avoid misdiagnosis and unnecessary surgical procedures. Case Report: A 54-year-old man was admitted to our emergency department complaining of abdominal pain in the lowerright quadrant, nausea, vomiting, and fever for 2 days. Physical examination revealed local rebound tenderness on the lowerright quadrant and a temperature of 38°C. Abdominal ultrasound showed that the intestinal loops were thickened and the surrounding mesenteric tissue was edematous in the right abdominal quadrant. Abdominal computed tomography was performed after a bolus administration of intravenous contrast material, and sigmoid colon position anomalies and diverticulitis were observed. The patient was treated medically, and diverticulosis was confirmed by colonoscopy. Conclusion: Clinical evaluation and ordered appropriate imaging methods by the emergency specialist is important in patients with abdominal pain on the lower-right quadrant who are admitted to the emergency department. Thus, rare anatomical variations mimicking acute appendicitis can be diagnosed accurately, and patients can be protected from undergoing unnecessary surgeries.