A football player with right flank pain and blood in the underwear after a hit is MOST suspicious for injury to which organ?

• A. Liver.
• B. Blunt injury to the kidney.
• C. Rib fracture.
• D. Spleen injury.

Answer: (B)

Pain in the flank after a blunt hit, plus blood in the underwear, points most strongly to a kidney injury. The kidneys are located along the posterior abdominal wall in the flank region and are vulnerable to blunt forces. When the kidney is injured, bleeding into the urine (hematuria) is a key clue, so the combination of flank pain and visible blood in the urine makes blunt injury to the kidney the most likely diagnosis.

Liver injury would typically produce right upper quadrant pain and signs of intra-abdominal bleeding rather than flank pain with hematuria. Spleen injury tends to present with left-sided upper quadrant pain. A rib fracture would cause chest wall pain and tenderness, not a primary sign of urinary bleeding.