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Abdominal and Pelvic Trauma

Category: Trauma Sources: raw/protocols/nm-sop-guidelines-treatment-2022.pdf Last updated: 2026-04-05

Overview

Abdominal and pelvic trauma is among the most dangerous and deceptive presentations in emergency medicine. The mechanism is frequently obvious — high-speed MVC, agricultural crush injury, fall from height, oilfield equipment contact. The pathology is frequently invisible. The peritoneal cavity can accumulate 1–2 liters of blood before distension becomes externally apparent. The retroperitoneal space can accommodate more. A patient with a ruptured spleen or a fractured pelvis can be in compensated hemorrhagic shock with a nearly normal blood pressure, reporting only diffuse abdominal tenderness.

The core concept: You cannot see internal bleeding. The mechanism tells you more than the physical exam does. A patient with a significant abdominal MOI is assumed to have internal injuries until proven otherwise, regardless of what the initial exam shows.

In rural NM — agricultural, oilfield, and highway settings — blunt abdominal and pelvic trauma is common and definitive care (surgical hemorrhage control) is far away. Early recognition and rapid transport are the only interventions that save these patients.

Mechanism and Organ Injury Patterns

Solid Organs — Bleed

The liver and spleen are the most commonly injured solid organs in blunt abdominal trauma. Both are highly vascular and have no capacity to control their own hemorrhage.

Liver: The largest solid organ, located in the right upper quadrant under the right lower ribs. Right-sided blunt impact (RUQ tenderness, right lower rib fractures) suggests hepatic injury. Liver lacerations can produce hemorrhage ranging from self-limiting to catastrophic. High-grade liver lacerations are a leading cause of death in blunt trauma.

Spleen: Located in the left upper quadrant, under the left lower ribs. Left-sided impact, left lower rib fractures, and left upper quadrant tenderness raise splenic injury concern. Kehr's sign — referred pain to the left shoulder — occurs when blood pools under the diaphragm and irritates it; the diaphragm shares C3–C5 dermatomal innervation with the shoulder. This is a pathognomonic sign of free intraperitoneal blood, classically from splenic injury. It is more pronounced when the patient is supine with legs elevated (blood flows toward the diaphragm).

Kidneys: Retroperitoneal organs, positioned against the posterior abdominal wall at the level of the lower thoracic and upper lumbar spine. Because they are retroperitoneal — behind the peritoneum — bleeding from the kidney does not enter the peritoneal cavity and does not cause abdominal distension. Renal injuries can bleed significantly without any visible abdominal finding. Mechanism (flank impact, seat belt sign across the flank, posterior lower rib fractures) and hematuria (blood in urine, not always visible prehospital) are the primary clues.

Hollow Organs — Rupture and Spill

The bowel (small and large intestine), stomach, and bladder are hollow organs. Blunt compression or deceleration shear forces can rupture them. Rupture allows contents (bowel content, urine, gastric acid) to spill into the peritoneal cavity, causing chemical peritonitis. However, peritonitis from hollow organ rupture often develops over hours — the initial exam may be deceptively benign. By the time the abdomen becomes rigid and the patient is clearly ill from peritonitis, significant time has passed.

Seat belt sign: A transverse or diagonal band of abdominal ecchymosis at the belt line after a restrained MVC correlates specifically with hollow organ injury. The belt arrests the torso while the bowel continues forward, crushing intestine against the spine. Any patient with a seat belt sign should be assumed to have hollow organ injury until proven otherwise by CT in the ED.

Aorta and Iliac Vessels — Catastrophic Hemorrhage

The abdominal aorta runs along the left side of the lumbar vertebrae. The iliac vessels branch at approximately L4. These are high-flow, high-pressure vessels. Injury to the abdominal aorta or iliac vessels causes hemorrhage that is incompatible with prolonged survival without surgical intervention. Deceleration injuries (high-speed MVC with sudden stop) can shear these vessels or cause intimal tears that progress to dissection or rupture. Penetrating injuries (GSW, stab wound) to the central abdomen are immediately concerning for great vessel injury.

Pelvic Fractures — The Hidden Hemorrhage

The pelvis is a rigid ring. Fracturing a ring requires breaking it in at least two places — single-point pelvic fractures are rare. The force required to fracture the pelvis is substantial: high-speed MVCs, crush mechanisms, falls from significant height. This is not a minor injury.

The danger of pelvic fractures is not the bone — it is the vasculature. The pelvic venous plexus (a dense network of veins) and the branches of the internal iliac artery run through the pelvic space. When the pelvic ring fractures and the fractured segments spread apart, this space expands — and the vessels tear. A pelvic fracture can hemorrhage 2–4 liters of blood into the pelvic retroperitoneum with no external signs whatsoever. There is no wound. There is no visible bruising initially. The blood is in a space you cannot see or palpate effectively. The patient may have a normal-appearing abdomen.

The clinical signs are the signs of hemorrhagic shock: tachycardia, falling blood pressure, pale cool diaphoretic skin, altered mental status. The only physical finding pointing to the source may be pelvic instability on palpation.

Why You Can't See It

The peritoneal cavity in adults can hold approximately 1.5–2 liters before visible abdominal distension occurs. The retroperitoneal space can hold more. By the time the abdomen looks distended to the examining provider, the patient has already lost a significant fraction of their circulating blood volume and is likely in decompensated or near-decompensated shock. Waiting for visible distension to diagnose internal abdominal hemorrhage means waiting until the patient is in extremis.

This is why the mechanism is the diagnosis. A patient with a significant abdominal MOI and any signs of shock has assumed internal hemorrhage until the CT scanner proves otherwise.

Assessment Findings

The Mechanism Tells You More Than the Patient Does

High-risk abdominal and pelvic MOI includes: - Restrained driver in high-speed MVC (>35 mph) — assume abdominal trauma - Unrestrained driver or passenger — any speed - Seat belt sign (bruising at the belt line) — hollow organ injury until proven otherwise - Steering wheel imprint on the abdomen - Crush mechanism (agricultural equipment, vehicle rollover, being pinned) - Fall from height onto the abdomen - Penetrating torso injury (GSW, stab wound) - Significant lower rib fractures — liver (right-sided) or spleen (left-sided) until proven otherwise

Any patient with these mechanisms should be triaged as a high-priority transport and assessed for signs of hemorrhagic shock throughout, regardless of what the initial abdominal exam shows.

Physical Findings

Abdominal tenderness: Palpate all four quadrants. Note which quadrant(s) are tender and the character of tenderness. Localized tenderness over the RUQ raises liver concern; LUQ raises spleen concern.

Guarding: Voluntary muscle tensing when the abdomen is palpated — the patient is protecting an area that hurts. Early finding.

Rigidity: Involuntary muscle tensing — the abdominal wall is board-like regardless of whether the patient is trying to relax. Rigidity is a late, serious finding indicating significant peritoneal irritation. It means the process is advanced.

Distension: Visibly enlarged abdomen. As discussed above, this is a late finding. Do not require distension to suspect internal hemorrhage.

Ecchymosis: Seat belt sign (transverse ecchymosis at belt line) = hollow organ injury concern. Flank ecchymosis (Grey Turner's sign) or periumbilical ecchymosis (Cullen's sign) suggest retroperitoneal hemorrhage — these are delayed signs, rarely present acutely.

Kehr's sign: Left shoulder pain, worsening with supine position and leg elevation, without shoulder injury. Blood under the left diaphragm from a splenic injury. This is one of the few signs that directly points to the organ injured.

Pelvic instability: With gloved hands, apply gentle, firm medial pressure on both iliac crests simultaneously. Movement, crepitus, or pain indicates pelvic instability — do this once only. Repeated pelvic palpation dislodges clots, disrupts tamponade, and increases bleeding. One assessment, then splint if unstable.

Signs of hemorrhagic shock: The vital sign picture often deteriorates before the abdominal exam becomes dramatic. Tachycardia is the earliest vital sign change. Narrow pulse pressure follows. Hypotension is a late finding in adults. Any patient with abdominal/pelvic MOI and tachycardia should be assumed to have internal hemorrhage until proven otherwise. See shock-physiology for the full compensation mechanism and shock for clinical recognition.

EMT-B Interventions

The Core Principle: You Cannot Stop Internal Bleeding in the Field

This is the most important concept in abdominal and pelvic trauma management. Direct pressure stops external hemorrhage. Tourniquets stop extremity hemorrhage. There is no prehospital intervention that stops bleeding from a lacerated liver, ruptured spleen, or torn iliac vein. The only definitive treatment for intra-abdominal hemorrhage is surgical hemorrhage control in an operating room.

The EMT-B's role is: 1. Recognize the mechanism and signs of internal hemorrhage 2. Prevent additional harm 3. Transport rapidly to a surgical facility

Interventions

High-flow oxygen: Maintain SpO2 ≥94%. Hemorrhagic shock reduces oxygen delivery to all tissues. The patient needs maximum oxygen-carrying capacity. NRB at 10–15 LPM initially.

Position: Supine, position of comfort. For isolated abdominal injury without spinal concerns, allow the position that minimizes pain — most patients are most comfortable supine with knees slightly flexed (reduces abdominal wall tension). Do not elevate legs if you suspect pelvic fracture (may increase pelvic space and bleeding).

Keep warm: Hypothermia is a coagulation killer. In the "lethal triad" of hemorrhagic shock (hypothermia + acidosis + coagulopathy), temperature is the component EMT-B can most directly control. Use blankets, close vehicle doors, control drafts. A hypothermic trauma patient bleeds more and clots less.

NPO: Nothing by mouth. The patient will likely go to the OR. Aspiration risk during induction of anesthesia is high in a non-fasted patient.

Do NOT palpate the abdomen repeatedly: One set of four-quadrant palpation for assessment. Repeated examination increases pain, can disrupt clot formation, and provides no additional clinical benefit prehosphorally. Document your initial findings and reassess vital signs, not the abdomen.

Priority transport: Scene time goal under 10 minutes for the unstable abdominal/pelvic trauma patient. Every minute on scene is a minute farther from the OR. Perform interventions en route whenever possible.

Pelvic binder or sheet wrap for suspected pelvic fracture:

If pelvic instability is found (movement or crepitus on the one gentle compression assessment), apply a pelvic binder or improvised sheet wrap at the level of the greater trochanters.

The mechanism: a pelvic fracture spreads the pelvic ring apart, increasing the volume of the pelvic space into which blood can hemorrhage. A pelvic binder closes this space — compressing the pelvis back toward its normal volume. This tamponades venous bleeding and bone-surface ooze, which account for the majority of pelvic hemorrhage (arterial injury is less common but more catastrophic). The binder does not stop arterial bleeding and is not a definitive treatment — it is a temporizing measure to reduce ongoing venous blood loss until definitive pelvic packing or angioembolization can be performed.

Apply at the level of the greater trochanters (widest part of the hips), not at the iliac crests. Apply firmly — loose application provides no benefit. Note the time of application and report to receiving hospital.

IV/IO access and fluid resuscitation (ALS scope):

Establishing IV/IO access is within ALS scope (EMT-I and EMT-P in NM). If ALS is available, two large-bore IVs are the target. Fluid resuscitation targets in hemorrhagic shock from abdominal injury (per NM General Trauma Guidelines): if SBP <90 mmHg or HR >120 or altered mental status, administer 500–1000 mL isotonic fluid bolus and reassess. In suspected TBI concurrent with abdominal injury, fluid resuscitate to SBP ≥110 mmHg.

Note: Do not delay transport to establish IV access. IV access should be established en route when possible.

Tranexamic acid (TXA) — ALS scope:

NM protocols authorize TXA for significant hemorrhage in patients >15 years of age: 1 gram over 10 minutes IV/IO, followed by 1 gram over 8 hours. TXA is an antifibrinolytic — it prevents clot breakdown and reduces total blood loss in trauma hemorrhage. This is ALS scope.

NM Protocol Notes

From NM EMS Treatment Guidelines (2022) — General Trauma Guidelines (p. 59–60):

Emphasis on patient care: Rapid assessment and management of life-threatening injuries, safe movement to prevent worsening injury, rapid transport to the closest most appropriate facility.

Primary survey: - Hemorrhage control of life-threatening bleeding - Airway patency; oxygen to maintain SpO2 ≥94% - Circulation: establish IV/IO (ALS); if SBP <90 mmHg, HR >120, or altered mental status → 500–1000 mL isotonic bolus and reassess (ALS) - If brain injury suspected: fluid resuscitate to SBP ≥110 mmHg (ALS) - Disability: spinal motion restriction if indicated - Exposure: roll patient to examine back; prevent hypothermia

Scene time: Goal <10 minutes for unstable patients or those needing emergent surgical intervention; majority of interventions performed en route.

Pain management (hemodynamically stable patients only — do not give if SBP <100): - Morphine: Adult 4–10 mg slow IV/IO (ALS scope) - Fentanyl: Adult 25–100 mcg slow IV/IO (ALS scope) - Note: Do NOT use NSAIDs (ketorolac) in trauma patients — increases bleeding risk

TXA: 1 gram IV/IO over 10 minutes for patients >15 years with significant hemorrhage, followed by 1 gram over 8 hours (ALS scope)

Abdominal pain — acute (NM protocol p. 37): For medical abdominal pain: NPO, position of comfort, transport to appropriate facility, IV/IO access, pain management if indicated. Note: Ketorolac is contraindicated in suspected bleeding (trauma, AAA rupture, GI bleed).

NREMT Relevance

Key concepts tested for abdominal and pelvic trauma: - Mechanism is the primary diagnostic tool — do not require obvious exam findings - Seat belt sign correlates with hollow organ injury — report it, prioritize transport - Pelvic fracture: apply binder or sheet, assess once only, do not repeat palpation - Kehr's sign: left shoulder pain from blood under the diaphragm = splenic injury until proven otherwise - Signs of hemorrhagic shock precede visible abdominal findings — tachycardia first - You cannot stop internal bleeding in the field — rapid transport is the intervention - NPO for all abdominal trauma patients - IV/IO and TXA are ALS scope; EMT-B manages airway, O2, position, warmth, and transport priority

Sources

  • raw/protocols/nm-sop-guidelines-treatment-2022.pdf — General Trauma Guidelines (p. 59–60); Abdominal Pain — Acute (p. 37); External Hemorrhage/Extremity Trauma (p. 68–69)