Trauma Surgery — Abdominal Trauma

Abdominal trauma initiates a cascade of physiologic derangements centered on hemorrhage, organ dysfunction, and inflammatory activation

• Hemorrhagic shock from solid organ and vascular injury: Blunt trauma to solid organs (liver, spleen, kidney) causes parenchymal disruption and laceration of the vascular pedicles, leading to rapid bleeding into the peritoneal cavity. The retroperitoneum is a capacious space that can accumulate 2–4 L of blood before distension becomes apparent on exam. In penetrating trauma, direct vascular injury (to the aorta, iliac vessels, or mesenteric vessels) causes exsanguinating hemorrhage. The magnitude of blood loss determines the degree of hypovolemic shock: Class I (<15% blood volume) is compensated via sympathetic activation and vasoconstriction; Class II (15–30%) causes mild tachycardia and anxiety; Class III (30–40%) produces hypotension and altered mental status; Class IV (>40%) is immediately life-threatening with profound shock. The inflammatory cascade triggered by ischemia-reperfusion injury, tissue damage, and bacterial translocation perpetuates coagulopathy and multi-organ dysfunction.

• Hollow viscus perforation and peritonitis: Penetrating trauma or blunt force sufficient to rupture bowel (small intestine, colon, stomach) allows spillage of luminal contents into the peritoneal cavity, initiating bacterial peritonitis and sepsis. The lipopolysaccharide (LPS) from gram-negative bacteria activates Toll-like receptor 4 (TLR4) on macrophages and neutrophils, triggering the release of TNF-α, IL-1β, and IL-6, which mediate the systemic inflammatory response syndrome (SIRS). Bacterial translocation across damaged mucosa, combined with immunosuppression in the acute trauma phase, creates a high-risk environment for overwhelming sepsis if perforation is not recognized and repaired promptly. The gastrointestinal barrier function is compromised by hypoperfusion during shock, facilitating bacterial migration into lamina propria and bloodstream.

• Solid organ injury with preserved vascularity: Modern trauma practice recognizes that many solid organ injuries (liver, spleen, kidney, pancreas) can be managed non-operatively if the patient is hemodynamically stable and appropriate monitoring is available. The underlying pathophysiology involves bleeding from parenchymal lacerations; if contained by the organ's capsule and surrounding peritoneum, a hematoma forms that can organize and reabsorb. However, if bleeding continues or the hematoma expands, tamponade fails and hemorrhagic shock ensues, necessitating operative intervention. The spleen is the most common intra-abdominal organ injured in blunt trauma; its rich vascular supply and friable parenchyma make massive hemorrhage possible, but splenic artery embolization and non-operative management have become standard for hemodynamically stable patients.

• Coagulopathy and the lethal triad: Trauma patients rapidly develop a coagulopathy that is multifactorial: dilutional (from crystalloid resuscitation), consumptive (from ongoing hemorrhage and activation of coagulation), and due to hypothermia (impairs enzymatic function of clotting factors). The lethal triad of hypothermia, coagulopathy, and acidosis creates a positive feedback loop where each component worsens the others. Hypothermia slows metabolic clearance of lactate (worsening acidosis) and impairs clotting enzyme kinetics; acidosis impairs platelet function and reduces catecholamine responsiveness; coagulopathy allows continued bleeding, perpetuating shock and acidosis. Modern damage-control resuscitation emphasizes permissive hypotension (target systolic BP 90 mmHg in blunt trauma without head injury) and massive transfusion protocols using high ratios of packed RBCs to FFP (1:1 or 1:1.5) to minimize crystalloid administration and hypothermia.

• Abdominal compartment syndrome (ACS): High intra-abdominal pressure from bleeding, visceral edema (from resuscitation), or packing during damage-control surgery can lead to ACS when intra-abdominal pressure exceeds 20 mmHg with evidence of organ dysfunction. The mechanism involves decreased venous return (impaired diastolic filling of the right ventricle), reduced microvascular perfusion, renal artery compression, and direct compression of the inferior vena cava. This creates secondary organ dysfunction (oliguria, elevated peak airway pressures, decreased cardiac output) that paradoxically worsens despite increased fluid administration. Prophylactic fascial closure should be avoided in damage-control scenarios; planned relaparotomy or temporary abdominal closure techniques allow subsequent fascial closure once edema resolves.

• Organ-specific ischemic injury: Mesenteric vascular injuries can cause intestinal ischemia and necrosis; even with vascular repair, the extent of bowel viability may not be immediately apparent (requiring "second-look" laparotomy 24–48 hours later). Renal artery thrombosis from blunt trauma can cause acute tubular necrosis and permanent renal loss if not rapidly revascularized. Pancreatic injuries are notoriously subtle on imaging but cause significant morbidity; pancreatic parenchymal contusion can progress to pancreatitis and pseudocyst formation, while ductal injury portends increased morbidity.

Blunt abdominal trauma

• Motor vehicle collisions (MVCs) are the leading cause of blunt abdominal trauma in most developed nations, accounting for 40–50% of cases. Mechanisms include ejection from vehicle, dashboard impact, steering wheel compression, and lap-belt syndrome (compression injury across the lower abdomen causing bowel perforation). Unrestrained occupants have higher injury severity.
• Falls from height represent the second most common cause, particularly in elderly patients and those with alcohol intoxication. Falls >10 feet or >2–3 times body height carry high risk of solid organ injury and retroperitoneal hemorrhage.
• Assaults and interpersonal violence, including blunt force trauma (punches, kicks, being struck with objects) and intimate partner violence, represent significant epidemiologic factors, particularly in urban settings.
• Pedestrian-vehicle collisions cause severe injuries due to the high velocity impact; pediatric patients are at particular risk because their smaller stature places the center of mass at a higher level relative to the vehicle.

Penetrating abdominal trauma

• Stab wounds (knife, ice pick, broken glass) account for 60–80% of penetrating abdominal trauma in urban settings. The depth and trajectory are unpredictable; a wound that appears superficial may have violated the peritoneum and damaged viscera.
• Gunshot wounds (GSWs) are more reliably associated with intra-abdominal injury (80–90%) compared to stab wounds (60%) because of the kinetic energy transfer and blast effect. High-velocity wounds create a primary tract plus temporary and permanent cavitation zones.
• Impaled objects (wood, metal, rebar) should never be removed in the pre-hospital or ED setting, as removal may precipitate massive hemorrhage; the object should be stabilized and removed only in the OR under controlled conditions.

Risk factors for severe injury

• Age extremes (very young and elderly) tolerate hemorrhage poorly due to reduced physiologic reserve.
• Pre-existing coagulopathy (anticoagulation, liver disease, thrombocytopenia) increases bleeding severity.
• Alcohol and substance intoxication impairs pain sensation, reducing reliability of abdominal exam and increasing risk of missed injury.
• High-impact mechanisms (ejection from vehicle, pedestrian struck at high speed, falls >15 feet) carry higher rates of multi-organ injury.

Cardinal signs of significant abdominal trauma

• Abdominal pain and tenderness: Pain is the most common presenting symptom but is unreliable as a sole marker of injury severity. Peritoneal irritation from blood, bile, or bowel contents causes localized or diffuse tenderness. The absence of pain does not exclude serious injury, particularly in patients with altered mental status, spine precautions, or concurrent painful injuries that dominate attention. Patients often underestimate severity when in shock due to catecholamine-mediated pain suppression.

• Abdominal distension: Accumulation of blood or intestinal contents causes visibly distended abdomen. Distension becomes apparent when >1.5–2 L of blood is present in the peritoneal cavity. Paradoxically, significant intra-abdominal bleeding may occur without obvious distension if bleeding is contained in the retroperitoneum (especially with pelvic or upper abdominal injuries).

• Tachycardia and hypotension: Hemorrhagic shock presents with reflex tachycardia (heart rate >100 bpm), cool extremities, diminished pulses, and eventually hypotension. Early compensation maintains blood pressure through sympathetic activation; hypotension indicates decompensated shock with >30% blood volume loss. In permissive hypotension protocols, a systolic BP of 90 mmHg is initially tolerated to minimize ongoing bleeding.

• Guarding and rigidity: Peritoneal irritation causes voluntary guarding (patient-controlled tensing of abdominal muscles) and involuntary rigidity (board-like hardness indicating severe peritonitis). Rigidity strongly suggests peritoneal violation (perforation or significant hemorrhage), mandating urgent imaging or surgical exploration.

• Rebound tenderness: Sudden release of palpating hand over area of peritoneal irritation causes pain, suggesting peritonitis from perforation or chemical irritation (bile, gastric acid, urine from bladder rupture).

• Seat belt sign: A bruise or abrasion across the lower abdomen in a restrained passenger indicates lap-belt syndrome, which carries high risk of hollow viscus perforation and mesenteric injury even without obvious intra-abdominal findings. This injury pattern is a strong indicator for repeat imaging or close clinical observation.

• Grey Turner's sign and Cullen's sign: Flank ecchymosis (Grey Turner) and periumbilical ecchymosis (Cullen) indicate retroperitoneal hemorrhage, typically from pancreatic injury or major vascular injury. These findings appear 12–24 hours after injury and are relatively late signs.

• Distended neck veins with hypotension: In penetrating chest-abdominal trauma, this combination suggests hemopericardium or tension pneumothorax rather than isolated abdominal bleeding, requiring immediate pericardiocentesis or chest tube placement.

• Pelvic instability: Rocking the iliac wings toward midline elicits pain and movement, indicating pelvic fracture with associated retroperitoneal hemorrhage. Pelvic fractures are present in 8–10% of blunt trauma patients but account for disproportionate mortality (8–35%) due to massive hemorrhage.

Clinical variants and special presentations

• Solid organ injury without peritoneal signs: Many patients with splenic or hepatic lacerations appear well-compensated initially; rapid deterioration can occur with delayed rupture of contained hematomas. A high index of suspicion is required.
• Retroperitoneal hemorrhage: Bleeding contained in the retroperitoneum may not produce abdominal distension or classic peritoneal signs, making diagnosis difficult without imaging.
• Delayed presentation: Hollow viscus perforation may be subclinical initially, with peritonitis developing over 6–24 hours as bacteria multiply and peritoneal inflammation develops.

Primary Survey (ABCDE)

Physical examination

• Inspection: Examine entire abdomen, flanks, back, and perineum for bruising, abrasions, penetrating wounds, distension, and asymmetry. Seat belt sign and contact marks guide mechanism assessment.
• Auscultation: Bowel sounds may be diminished or absent in peritonitis, though absence is non-specific in acute trauma. Presence does not exclude serious injury.
• Percussion: Hyperresonance may indicate free air (pneumoperitoneum); percussion tenderness suggests peritoneal irritation.
• Palpation: Systematically palpate all four quadrants and flank, noting tenderness, guarding, and rigidity. Assess for pelvic stability by applying gentle compression to iliac wings and symphysis pubis.
• Rectal exam: Evaluate for gross blood (suggesting lower GI source), anal tone (spinal injury), and prostate position (bladder rupture suspected if high-riding prostate in men).

Focused Assessment with Sonography for Trauma (FAST)

1. 1.Pericardial view: Place probe in epigastrium at left sternal border; assesses for hemopericardium (indicates penetrating thoracoabdominal trauma with cardiac injury). Sensitivity 90–95% for hemopericardium.
2. 2.Right upper quadrant (Morison's pouch): Probe between liver and kidney in midaxillary line at 4–5th intercostal space; most sensitive location for free fluid. Sensitivity 85–90% for 200–500 mL of fluid in upright patients.
3. 3.Left upper quadrant (splenorenal junction): Assess for free fluid between spleen and kidney; slightly less sensitive than RUQ.
4. 4.Pelvic view: Transverse view above symphysis pubis assesses for free fluid in pouch of Douglas and paravesical spaces; most dependent area when supine.

Sensitivity of FAST: 73–96% for free intra-abdominal fluid in blunt trauma; higher in hemodynamically unstable patients with larger quantities of blood. Negative FAST does not exclude significant injury; 5–15% of hemodynamically stable patients with negative FAST have intra-abdominal injury on CT. Repeat FAST should be performed serially if clinical suspicion remains high.

Diagnostic peritoneal lavage (DPL)

Computed tomography (CT) with IV contrast

CT is the gold standard for hemodynamically stable patients and provides detailed anatomic information regarding organ injury, active bleeding (arterial blush), and solid organ laceration grade. Multi-detector CT with arterial and portal venous phase imaging and 3D reconstruction is standard. In unstable patients, CT delays resuscitation and operation; these patients should proceed directly to OR if FAST is positive or clinical suspicion is high.

• Liver injuries: Grade I–II are minor (confined lacerations); Grade III–IV indicate major injury with higher risk of failure of non-operative management; Grade V is massive injury or hepatic vein/IVC involvement.
• Splenic injuries: Grade I–II are minor; Grade III–IV carry 10–50% failure rate with non-operative management, especially if associated with hypotension.
• Renal injuries: Grade I–III are typically managed non-operatively; Grade IV (involving collecting system) or V (vascular pedicle injury) may require intervention.

Laboratory tests

• Hemoglobin/hematocrit: Initial value may be falsely reassuring if bleeding is

Immediate stabilisation (ATLS, American College of Surgeons Committee on Trauma)

• Airway, breathing, hemorrhage control: two large-bore IVs, warmed products, external compression, pelvic binder at the greater trochanters for suspected pelvic-ring hemorrhage. Keep the patient warm — hypothermia drives the lethal triad described above.
• Damage-control resuscitation: balanced transfusion of pRBC:FFP:platelets in a 1:1:1 ratio (PROPPR trial) rather than crystalloid; minimize crystalloid to avoid dilutional coagulopathy and visceral edema. Give supplemental calcium (calcium chloride or gluconate) during massive transfusion because citrate chelates ionized calcium.
• Antifibrinolytic: tranexamic acid, given within 3 hours of injury in bleeding trauma patients (CRASH-2); late administration is not beneficial.

Deciding operative vs non-operative (EAST and WSES practice management guidelines)

• Hemodynamically unstable with positive FAST, peritonitis, evisceration, or free air: immediate exploratory laparotomy. No CT.
• Hemodynamically stable blunt solid-organ injury: non-operative management with serial exams, serial hematocrit, and monitored bed is the standard of care for liver, spleen, and kidney.
• Angioembolization: for contrast blush/pseudoaneurysm on CT or high-grade splenic injury in a stable patient — the main escalation step short of laparotomy.
• Penetrating trauma: anterior abdominal gunshot wounds violating the peritoneum go to laparotomy; selected stab wounds in stable patients may undergo local wound exploration, serial exam, or laparoscopy.

Adjuncts

• Perioperative antibiotics: a cephalosporin with anaerobic coverage (e.g., cefoxitin) for known or suspected hollow-viscus injury; prolonged prophylaxis is not supported.
• Tetanus prophylaxis per CDC schedule for all penetrating wounds.
• Post-splenectomy vaccination (pneumococcal, meningococcal, H. influenzae type b) per ACIP, ideally ~14 days postoperatively.

Contraindicated / avoid

• CT in the unstable patient; removing an impaled object outside the OR; primary fascial closure after damage-control laparotomy (precipitates abdominal compartment syndrome — leave a temporary closure); large-volume crystalloid resuscitation.
• Permissive hypotension is not used in traumatic brain injury, where cerebral perfusion pressure must be maintained.

Emergencies (recognize immediately)

• Abdominal compartment syndrome: bleeding, packing, and resuscitation-induced visceral edema raise intra-abdominal pressure, collapsing the IVC and reducing preload. Signalled by rising peak airway pressures, oliguria, and falling cardiac output despite fluids; bladder pressure >20 mmHg with organ dysfunction confirms it. Treatment is decompressive laparotomy.
• Failure of non-operative management / delayed splenic rupture: a contained subcapsular hematoma expands and ruptures days later. Signalled by new tachycardia, falling hematocrit, or Kehr's sign (left shoulder pain from diaphragmatic irritation) — go to OR or angioembolization.
• Missed hollow viscus injury: small perforations or devascularized bowel from mesenteric tears are frequently occult on initial CT. Signalled by fever, leukocytosis, and progressive peritonitis 12–48 hours after admission — the classic seat-belt sign trap.
• Overwhelming post-splenectomy infection (OPSI): loss of splenic clearance of encapsulated organisms; fulminant Streptococcus pneumoniae sepsis, highest risk in children and in the first few years after splenectomy.

Non-emergent but high-yield

• Intra-abdominal abscess: contamination plus devitalized tissue; presents with persistent fever and leukocytosis — CT-guided drainage.
• Pancreatic fistula and pseudocyst: ductal injury leaks amylase-rich fluid; suspect with persistent drain output high in amylase.
• Biloma / bile leak after hepatic injury: right upper quadrant pain and fluid collection; managed with ERCP stenting and drainage.
• Enterocutaneous fistula and ventral hernia: consequences of the open abdomen and repeated laparotomy.
• Transfusion-related complications: TRALI, TACO, hyperkalemia, and citrate-induced hypocalcemia, which worsens coagulopathy and hypotension.
• Venous thromboembolism: immobility plus tissue-factor release; prophylaxis is delayed but should be started as early as bleeding risk allows.
• ARDS and multi-organ dysfunction: ischemia-reperfusion and SIRS after prolonged shock.
• Post-traumatic stress disorder is common and under-screened after major trauma.

• The FAST algorithm is the single most tested decision tree: unstable + positive FAST → immediate laparotomy; unstable + negative FAST → look elsewhere (chest, pelvis, retroperitoneum, external) and consider DPL; stable + positive FAST → CT with IV contrast; stable + negative FAST → observe with serial exams.
• Ordering a CT in a hemodynamically unstable patient is the classic wrong answer. The unstable patient's "best next step" is the operating room, not the scanner.
• A negative FAST never excludes injury — it does not detect hollow viscus perforation, retroperitoneal (pancreas, duodenum) injury, or diaphragm injury.
• Seat-belt sign across the lower abdomen → hollow viscus and mesenteric injury plus Chance fracture (flexion-distraction injury of the lumbar spine). Look for delayed peritonitis.
• Kehr's sign (left shoulder pain) = diaphragmatic irritation from splenic blood. Left lower rib fractures (9–11) → spleen; right lower rib fractures → liver.
• Handlebar injury in a child → duodenal hematoma (gastric outlet obstruction, coiled-spring sign) or pancreatic transection over the vertebral body.
• Give tranexamic acid within 3 hours of injury in bleeding trauma patients (CRASH-2); transfuse in a 1:1:1 ratio (PROPPR), not crystalloid.
• Never remove an impaled object outside the OR, and never close the fascia primarily after damage-control laparotomy — both are examiner favorites for abdominal compartment syndrome and exsanguination.
• After splenectomy, vaccinate against S. pneumoniae, N. meningitidis, and H. influenzae type b (ACIP); the distractor is forgetting meningococcal or Hib coverage.
• Common distractor: assuming a normal initial hemoglobin excludes hemorrhage — acute blood loss is isovolemic until fluid shifts or resuscitation occur.