Background: Scientific evaluation of trauma patients should follow a logical order and notice to all probable causes of shock can be life saving for all trauma patients.

Case Report: In this case report, a 30-year-old man was referred to the hospital by Emergency Medical Services because of penetrating trauma to the pelvis caused by gunshot. During Primary Survey because of muffle heart sounds, cardiac bedside ultrasonography was performed and pericardial effusion and right ventricle diastolic collapse were found which are symptoms for cardiac tamponade. Then pericardiocenthesis was immediately performed and after putting a catheter in the pericardium, patient was transferred to the operating room. Rupture of the bladder, bowel, sigmoid and diaphragm in the abdomen and pericardium and epicardium in the chest were treated by the surgeon after 3 times of surgery. During follow-up period patient had no long term sequel.

Conclusion: At the beginning, the cause of shock seemed to be hemorrhagic shock but after diagnostic peritoneal aspiration (DPA), it was ruled out and heart sounds and bedside cardiac sonography that is part of ATLS protocol at last caused to diagnosis of pericardial tamponade due to gunshot pericardium and epicardium injury.