A 45-year-old man presents with sudden-onset severe right flank pain that radiates to the groin. He reports nausea and vomiting. On examination, he is in significant distress and has costovertebral angle tenderness. Urinalysis shows haematuria. What is the most likely diagnosis, and what is the initial diagnostic test of choice? A. Renal cell carcinoma; order a CT urogram B. Acute appendicitis; perform an abdominal ultrasound C. Kidney stone (renal calculus); perform a non- contrast CT scan D. Pyelonephritis; order a urine culture and sensitivity E. Inguinal hernia; perform a physical examination Answer: C. Kidney stone (renal calculus); perform a non-contrast CT scan Explanation: This patient presentation with severe flank pain, nausea, vomiting, costovertebral angle tenderness, haematuria, and a high suspicion of a kidney stone (renal calculus). The initial diagnostic test of choice for confirming the diagnosis and assessing stone size and location is a non-contrast CT scan. Renal cell carcinoma typically presents with different clinical features and is not the most likely diagnosis in this context
