Snapshot A 30-year-old male victim of an automotive hit-and-run incident presents to the ED. Initial primary survey reveals no airway obstruction and good ventilation. Two large bore IV's are inserted and blood pressure is 95/60 mmHg, pulse is 95/min, respirations are 18/min, and SaO2 is 95% on room air. One liter of Lactated Ringer's is started. Secondary survey reveals no obvious source of blood loss. Despite this and fluid resuscitation, the patient's blood pressure drops to 85/55 mmHg. A FAST ultrasound exam reveals fluid surrounding the spleen and in Morrison's pouch. The patient is rushed to the OR for an exploratory laparotomy. Introduction Overview abdominal trauma is trauma to the abdomen causing visceral damage and hemorrhage treatment depends on extent of trauma Epidemiology Incidence difficult to recognize clear symptoms early blunt abdominal trauma 2/3 of all intraabdominal injuries mortality rate of ~8.5% motor vehicle crash (MVC) is main mode of injury penetrating abdominal trauma 1/3 of all intraabdominal injuries mortality rate ~12% 95% of all penetrating trauma associated with gunshot and stab wounds higher risk of wound site infection and abscess formation Demographics 2/3 injuries occur in males peak incidence between ages 14 and 30 Location blunt spleen is most commonly injured ogan, liver is second penetrating liver is most commonly injured organ Risk factors substance use ownership or access to firearms motor vehicle operation ETIOLOGY Pathogenesis blunt abdominal trauma divided into three mechanisms 1st: rapid change in organ momentum and speed causes shearing forces to tear organs 2nd: crush injury due to organ compression against blunt object and rigid structures in body (i.e. bones) 3rd: external compression due to rise of pressure inside organ, especially hollow organs, leading to organ rupture penetrating abdominal trauma divided into two mechanisms 1st: direct damage via tissue penetration 2nd: pressure damage from speed of penetrating object causes fragmentation of organ Presentation History important to ascertain mechanism of injury from initial report to determine workup unprotected trauma pedestrian victims of MVC, motorcycle / bicycle crash, assaults with objects high-energy trauma MVC with no restraints, known high speeds, death at scene, substantial vehicular damage falls greater than 15 feet minor trauma in patients with limited reserve to tolerate injury elderly, patients with chronic debilitating disease, immunosuppressed seatbelt-associated injuries retroperitoneal duodenal trauma intraperitoneal bowel transection mesenteric injury lumbar spine injury Symptoms symptoms and signs of blood loss may not be evident Physical exam inspection tachycardia, tachypnea, oliguria, febrile, hypotension primary and secondary survey abrasions, contusions, seatbelt sign, distension bruits, bowel sounds on auscultation referred pain to shoulder provocative tests tenderness with and without rebound, rigidity, and guarding digital rectal exam nasogastric tube for bowel decompression Foley catheter placement if patient cannot void spontaneously Imaging Radiograph indications free air under diaphragm, hernia, air-fluid levels, fractures limitations soft tissue not visualized FAST ultrasound indications presence or absence of free fluid in peritoneal, pleural, pericardial cavities rapidly (<5 minutes) NOT used to identify specific organ injuries limitations if patient has ascites, FAST will be a false positive Diagnostic peritoneal lavage (DPL) indications most sensitive test for intraperitoneal blood if > 10 ml gross blood, WBC > 500, amylase > 175, and/or bile/bacterial/foreign material found, DPL is considered positive NOT for retroperitoneal bleed or diaphragmatic rupture limitations rarely used (takes 1 hour) CT scan indications most specific test for all of above limitations significant radiation exposure NOT used if patient is hemodynamically unstable Studies Serum labs complete blood count electrolytes coagulation type and cross creatine kinase lipase / amylase liver function tests arterial blood gas blood EtOH urine or serum β-hCG (pregnancy test) urinalysis toxicology screen Differential Cardiac trauma cardiogenic shock can include cardiac tamponade, contusion, laceration bleeding above diaphragm Pulmonary trauma impaired oxygenation and ventilation diaphragmatic injury can cause bleeding to spill into abdomen Management Medical when to obtain imaging in blunt abdominal trauma equivocal abdominal physical exam multiple trauma patient with altered mental status 2/2 head trauma or drugs/alcohol patient with suspected spinal cord injury causing abdominal anesthesia unexplained shock/hypotension fractures of lower ribs, pelvis, spine start with FAST ultrasound for blunt abdominal trauma Surgical blunt abdominal trauma if positive: hemodynamically (HD) unstable: start IV fluids go to OR for laparotomy HD stable: get CT (sometimes CT may be a better initial step depending on the context) if negative: HD unstable: repeat FAST or get DPL but mechanism of injury is significant: get CT if no risk factors: observe with repeat serial physical exams if equivocal: HD unstable: get DPL HD stable: get CT solid organ injuries in blunt abdominal trauma treat based on hemodynamic stability, not specific injury if unstable, go to OR for laparotomy if stable, spleen/liver/kidney lacerations and hematomas can be graded higher grade portends increased risk of bleeding consider angiography with embolization hollow viscus injuries in blunt abdominal trauma evidence of perforation (free air in peritoneal cavity) next best step: go to OR for laparotomy penetrating abdominal trauma if gunshot or stab wound next best step: go to OR for laparotomy any gunshot wound below the nipple line is considered to be abdominal if shock, peritonitis, evisceration, free air in abdomen, or blood in NG/Foley/DRE nest best step: go to OR for laparotomy retroperitoneal trauma classified and triaged by zones on imaging zone 1 (central) high risk of bleeding from major vessels, pancreas, and duodenum next best step: go to OR for laparotomy zone 2 (perirenal) if stable, next best step: continue to observe if HD unstable or penetrating trauma, first obtain contralateral renal function next best step: go to OR for exploration based on renal function zone 3 (pelvic) first control bleeding with pelvic binder if stable and blunt trauma, no surgical exploration next best step: consider angiography and embolization if unstable and penetrating trauma, surgical exploration may be necessary Complications Surgical wound infection manage with surgical debridement and broad-spectrum antibiotics Shock resuscitate with a massive transfusion protocol (do NOT just give crystalloids) positive pressure ventilation can worsen hypotension secondary to increased intrathoracic pressure