An unexpected finding of cardiac injury penetrating the diaphragm in a suspected abdominal trauma case.

We report a rare case of penetrating abdominal trauma involving right ventricular injury. An 81-year-old man presented with a stab wound in the upper abdomen and hemodynamic instability. Hemorrhagic shock was initially suspected to be due to intra-abdominal organ damage. Emergency laparotomy revealed no evidence of intra-abdominal organ injury; however, subsequent thoracotomy and sternotomy identified cardiac tamponade from right ventricular injury caused by a penetrating object that traversed the diaphragm. Prompt surgical intervention enabled successful resuscitation. This case highlights the diagnostic challenge of "junctional zone" trauma, where both thoracic and abdominal organs may be involved. Despite advanced age, the patient was discharged in good condition.