MVCs account for the majority of cases of significant

blunt abdominal trauma across all demographic groups,

with the spleen by far the most commonly involved organ.

With penetrating trauma, abdominal SWs are roughly 3

times more common than GSWs. That said, the latter

accounts for roughly 90% of fatal injuries, as SWs are far

less likely to violate the peritoneal cavity and cause

significant injury. Abdominal GSWs most commonly

CHAPTER 88

I r ..-··-

/

.A. Figure 88-1. Anterior abdominal region.

involve the small bowel, colon, and liver, as these organs

take up the largest volume within the abdominal cavity.

Abdominal SW s most commonly affect the liver, but

laparotomy is required in only one quarter to one third of

patients.

The severity of injury is proportional to the amount of

energy transferred to target tissues. Blunt abdominal trauma

causes injury primarily by the direct transmission of external forces to underlying organs. Solid viscera, namely the

spleen and liver, are the most likely structures to be involved.

Hollow viscera can be injured when sudden crushing forces

induce a rapid spike in intraluminal pressure and secondary

rupture. Blunt trauma can also transmit shearing forces to

underlying structures. Significant injury is most c ommonly

seen in areas of transition from fixed to mobile positions

such as the small bowel at the ligament of Treitz or the

ileocolic junction.

In penetrating trauma, SWs result in low-energy

mechanisms that cause injury only to those tissues directly

impacted by the stabbing implement. As most assailants are

right-hand dominant, the left upper quadrant is the most

likely region to be affected. GSW s, on the other hand, transmit substantial amounts of energy and frequently result in

significant intra-abdominal injury. Missile size, stability, and

velocity all help to determine the amount of energy imparted.

High -velocity projectiles (> 2,000 ftl sec) as seen with combat

wounds and hunting rifles can create waves of energy that

result in temporary cavity formation and the disruption of

tissues remote from the missile tract. In fact, intraperitoneal

injury has been known to occur with high-velocity GSWs in

the absence of peritoneal violation. Shotgun injuries are

unique in that the velocity of the pellets decreases rapidly

with the length of distance traveled. Furthermore, the spread

of the pellets increases proportionally to the distance

between the victim and the shooter. Wounds with a pellet

spread of 1 0-25 em most likely occurred at a distance of 3-7

yards and possess sufficient energy to penetrate into the

peritoneal cavity. Finally, the potential for introducing contamination in the form of clothing or wadding further

complicates GSW injuries.

CLINICAL PRESENTATION

..... History

A rapid primary survey and patient stabilization should

always take precedence over a thorough medical history.

That said, obtain a quick AMPLE (Allergies, Medications,

Past illnesses, Last meal, Events preceding injury) history as

with all trauma patients and ask focused questions to

delineate the potential severity of mechanism. Emergency

medical service personnel can provide invaluable informa ­

tion about the mechanism of injury, initial scene evaluation, and response to interventions provided during

transport. With patients from an MVC, inquire about the

Figure 88-2. Thoracoabdominal reg ion.

ABDOMI NAL TRAUMA

severity of vehicular damage, seatbelt use, airbag deployment, need for patient extrication, and injuries to other

occupants. For GSW victims, ask about the number of

shots fired and the type of weapon involved.

Ask all patients about the presence of abdominal pain,

vomiting, hematemesis, and rectal bleeding. Pain in the

shoulder that is not associated with either tenderness on

exam or discomfort with shoulder movement suggests that

free intraperitoneal blood is irritating the diaphragm

inducing referred pain (Kehr sign).

� Physical Examination

Check a complete set of vital signs and proceed with the

primary survey. Any evidence of hemodynamic instability

suggests hemorrhagic shock and requires aggressive

intervention.

Perform a thorough examination of the chest and abdomen.

Inspect the patient and note any contusions, hematomas, and

abdominal distention. Lap-belt ecchymoses are highly con ­

cerning for underlying hollow viscus injuries or vertebral

body (Chance) fractures. Note all open wounds and identify

the zone of injury. GSWs may not follow a linear trajectory,

and a thorough examination of the entire body is necessary

to document all potential penetrating wounds. Look for

retained implements and eviscerations as each require operative intervention. Carefully palpate all 4 quadrants to detect

any point tenderness or signs of evolving peritonitis. Perform

a rectal exam to assess for the presence of gross blood. Keep

in mind that the abdominal examination in isolation lacks

adequate sensitivity to identify all patients with significant

injuries that require operative intervention.

DIAGNOSTIC STUDIES

� Laboratory

As with all victims of significant trauma, obtain a complete

blood count, metabolic panel, coagulation studies, and type

and screen. Serial hemoglobin measurements, and, if avail ­

able, bedside lactate and base deficit analysis may help to

determine the severity of injury and physiologic response to

resuscitation. Obtain a urine sample for rapid pregnancy

testing, urinalysis, and toxicology screening. Hemodynamically stable adults without evidence of gross blood on

bedside urinary inspection do not require a urinalysis to

search for microscopic hematuria, as significant GU injury

is highly unlikely. Liver function tests and pancreatic

enzymes are nonspecific and poorly predictive of injury

severity. As such, they are of minimal clinical utility in the

routine evaluation of patients with abdominal trauma.

� Imaging

Obtain an upright chest x-ray (CXR) in all patients to

detect subdiaphragmatic free air suggestive of an underlying

hollow viscus injury or the intrathoracic herniation of

abdominal viscera indicative of a diaphragmatic rupture.

In patients with penetrating thoracoabdominal trauma,

Figure 88-3. CT sca n demonstrating a splenic laceration (arrow). Note the free fluid around the liver.

carefully review the CXR to rule out an underlying pneumothorax. Obtain an anteroposterior film of the pelvis in

blunt trauma victims to rule out unstable pelvic fractures

and stabilize any visualized injuries by tightly securing a

bed-sheet around the patient's waist to tamponade off any

active pelvic bleeding. Place r adiopaque markers (eg, electrocardiogram leads) over any open wounds in GSW victims before imaging to help determine the path of the

projectile( s).

Pursue computed tomography (CT) imaging of the

abdomen and pelvis in all stable blunt trauma patients to

detect solid organ injury and hemoperitoneum (Figure 88-3).

This modality is especially useful in patients whose exams are

limited by distracting injuries or altered mental status. With

penetrating trauma to the back and flank, order a "triple

contrast" CT scan (by mouth, intravenous, and per r ectum)

to rule out intraperitoneal and retroperitoneal injury. CT

imaging can also be used to diagnose peritoneal violation in

patients with abdominal SWs. Of note, CT imaging is

inadequately sensitive to exclude small diaphragmatic injuries with penetrating thoracoabdominal trauma and isolated

hollow viscus injuries with significant blunt t rauma.

PROCEDURES

� FAST Scan

Focused assessment with sonography for trauma (FAST)

imaging is a widely available bedside procedure that can

detect volumes of free intraperitoneal blood as low as 100 mL.

It is easy to perform, quick ( <5 minutes), noninvasive, and

readily repeatable. The sensitivity of a FAST exam is directly

proportional to the volume of free intraperitoneal blood,

and this modality is highly sensitive in cases in which intra ­

peritoneal hemorrhage is significant enough to produce

hemodynamic instability. A positive FAST exam in an

unstable patient with blunt abdominal trauma necessitates

emergent laparotomy. See Chapter 8 for further details.

CHAPTER 88

..... Diagnostic Peritoneal Lavage (DPL)

Although largely supplanted by less invasive modalities such

as Cf and FAST, DPL may continue to play a role in the rapid

bedside detection of free intraperitoneal blood in grossly

unstable patients with equivocal FAST exams. This procedure

can be broken down into 2 basic steps. Begin by inserting an

1 8-gauge needle into the peritoneal cavity and attempting to

aspirate free intraperitoneal fluid. An aspirate of � 10 mL of

gross blood or obvious intestinal contents warrants operative

laparotomy. In patients with negative aspirates, insert a guidewire through the needle and place an intraperitoneal catheter

via the Seldinger technique. Infuse 1 L of normal saline into

the peritoneal cavity and then allow it to drain via gravity

back into the empty saline bag. The collected fluid should

then be sent to the lab for cell count analysis. In blunt abdominal trauma, a count > 100,000 red blood cells (RBCs)/JlL is

considered the threshold for detecting significant visceral

injury and the need for laparotomy. For abdominal GSWs, a

count >5,000--10,000 RBCs/JlL is considered positive. For

patients with thoracoabdominal SWs, a similar count of

5,000--10,000 RBCs/JlL is used to exclude diaphragmatic

injuries. For all other abdominal SWs, a cut-off of > 100,000

RBCs/JlL is used.

..... Local Wound Exploration (LWE)

This is a useful modality for excluding peritoneal violation

in patients with anterior abdominal SWs. Carefully extend

the margins of the injury as necessary to facilitate adequate

visualization of the base of the wound. The use of copious

local anesthetics is a must. This technique is far preferable

to blindly probing the wound with blunt instruments.

Assume peritoneal penetration in cases in which the base

of the wound cannot be clearly identified. The deep

exploration of thoracoabdominal wounds is generally

avoided, although LWE may be reasonable to confirm the

depth of very superficial slashing-type injuries.

MEDICAL DECISION MAKING

Begin all evaluations with a rapid primary survey and

complete set of vital signs. Emergent laparotomy is

generally indicated in all unstable patients with either

penetrating abdominal trauma or blunt abdominal trauma

and positive FAST imaging. Regardless of hemodynamic

condition, patients with GSWs that clearly violate the

peritoneal cavity require emergent laparotomy due to the

high rate of significant underlying injury.

Hemodynamically stable patients warrant a work-up

before deciding on the need for surgery. For victims of

penetrating trauma, this might include LWE with anterior

abdominal SWs, plain radiographs to localize radiopaque

foreign bodies, FAST imaging to look for pericardia! and

intraperitoneal free fluid, CT imaging to help determine

the need for and approach to any operative intervention,