Abdominal Trauma

Evaluation and Management

Rui Z. Fernandes, Srinivas Ramachandra and Phillip Pirgousis

Abdominal trauma assessment and management is a significant part of trauma management. Primary survey and circulation both involve an abdominal examination for determining hemodynamic stability. Thus, maxillofacial trauma surgeons must be cognizant of concomitant abdominal injuries and be proficient in the diagnosis, prioritization of acute management, and application of abdominal trauma management principles.

Many algorithms and treatment protocols have been devised over the years to assess and treat individuals with multisystem traumatic injuries. The most widely accepted and used worldwide is the Advanced Trauma Life Support (ATLS) system developed by the American College of Surgeons Committee on Trauma. This begins with an initial assessment or primary survey of the trauma patient comprised of the familiar ABCDE—airway, breathing, circulation, disability, and exposure.

Abdominal examination is an adjunct to primary survey in hemodynamically unstable patients forming part of the assessment of circulation, specifically to confirm or exclude the abdomen as the source of concealed bleeding. In a stable patient with a history of chest or abdominal injury or symptoms, the abdominal examination is part of a secondary and tertiary survey.¹ Facial or closed head injury examination is secondary in the evaluation unless significant airway instability impedes proper access and control of ventilation. Any wound from the nipple to perineum anteriorly, to the vertebral column posteriorly, and bilateral flanks are the boundaries of abdominal review and the common areas of trauma. Mechanisms of injuries may be penetrating or blunt. The most common cause of mortality in abdominal trauma is secondary to delayed resuscitation or excessive hemorrhage with inadequate volume resuscitation. Intra-abdominal organ injury and rupture or perforation precipitates gastrointestinal (GI) content spillage into the peritoneal cavity, frequently leading to peritonitis and delayed mortality from severe sepsis.

The abdomen can be deceptively benign on initial assessment, with a precipitous change in clinical status. The most significant pitfall is delayed recognition of occult abdominal injury.²

Epidemiology

Injury is the fifth leading cause of death in the United States and is the leading cause of death for those in their first 3 decades of life. Abdominal trauma is commonly encountered in these cases. The United States, South Africa, and some South American countries have a high incidence of penetrating injuries from stab and gunshot wounds. In the United Kingdom, Australia, New Zealand, and most European countries, blunt trauma predominates as the cause for hospital admissions, although the incidence of penetrating trauma is rising.

Mechanisms of Injury

A concentrated area of force on the abdominal area has a higher risk of injury to underlying organs (Fig. 9-1). The impact can be in the form of a blunt object such as a steering wheel or car door. The vector and velocity of the trauma become important to the clinician. To understand the mechanism of injury better, the treating physician should seek to obtain information from the injury report or from the paramedics. Often, the transporting medical personnel have obtained the accounts from witness information as well as assessment from the injury scene. This information forms a vital component of the clinical history and the likelihood of underlying injury.

FIGURE 9-1 Mechanism of injury algorithm.

Examination

The abdomen is divided into three parts for consideration of injury—retroperitoneum and peritoneal and pelvic cavities. The pelvic cavity is comprised of the rectum, bladder, iliac, and uterine structures.

Abdominal examination in trauma must be a continuum of evaluative and diagnostic steps rather than a brief physical review of the patient. Any patient with chest and abdomen complaints is assumed to have intra-abdominal injury until proven otherwise.³

Undress and expose the patient from chest to perineum. Inspect and note the size, shape, and injury type: abrasions, lacerations, point of entry and exit of penetrating wounds, and evisceration of structures and organs. Gentle palpation of the abdomen may suffice in most cases, including an examination for pelvic stability. Urethral, perineal, and rectal examinations are mandatory in abdominal review. Any induration of the abdominal wall or underlying organs is a notable finding and needs further diagnostic workup. Auscultation findings may be nonspecific unless followed by further examination.

A rectal examination is invaluable, because the presence of frank blood frequently indicates anorectal disruption; prostrate position and sphincter tone on voluntary squeeze by the patient yields critical neurologic information. Similarly, inspection of the urethral meatus may indicate underlying pelvic, bladder, and urethral trauma.

Trauma Scores and Indices

Trauma grading systems are comparative indices for quantification and description. These can be extrapolated for diagnostic, therapeutic, and prognostic measures. Commonly used indices are the Abbreviated Injury Scale (AIS) and the Penetrating Abdominal Trauma Index (PATI).4,5 Previous editions of AIS (severity scale from 1 to 6) were for blunt trauma; the most current modification extends to include penetrating trauma. PATI has individual organ scores summative to a score of 25. Its major drawbacks are inadequate quantification for multiple complex injuries involving a specific anatomic area.

Adjuncts to Physical Examination

Most adjunctive examinations are not performed in a stable, alert, cooperative, and asymptomatic patient who has suffered low-force transfer to the abdominal wall or internal organs. Any complaints of shoulder or abdominal pain, nausea, unrestrained patients, impairment by alcohol or drugs, visible contusive signs, and open injuries mandate abdominal examination adjuncts.³

Adjunctive Diagnostic Studies

Gastric Tubes.

Gastric air is common in trauma, requiring decompression with nasogastric or orogastric tubes. Gastric tube insertion is a diagnostic and therapeutic procedure if no contraindication exists. Craniofacial injuries with unstable upper midfacial fractures are particular situations in which nasogastric tube insertion is contraindicated.

Urinary Catheters.

Urinary catheters are useful for decompression of the bladder, urinalysis for macroscopic and microscopic hematuria, and monitoring adequacy of fluid resuscitation. Scrotal hematoma, perineal ecchymosis, pelvic fractures, blood at the meatus, high-riding prostrate with unstable pelvis, hematuria (>50 red blood cells [RBCs] per high-power field [HPF]) and inability to void are relative contraindications to urethral catheterization. In these cases, retrograde urethrography (RUG) is often used to diagnose urethral injury.⁶

Diagnostic Workup

Laboratory Studies

Along with clinical examination, concurrent hematology and biochemical laboratory tests are required. These include blood typing and cross-matching for unstable patients as well as operative candidates, with a direct communication to the blood bank. Hematocrit is a worthy evaluation for ongoing management. A leukocyte count will not be specific but a significant increase is noted in solid organ injuries caused by catecholamine-induced demargination. The leukocyte count may not be an absolute essential for acute trauma management. Serum amylase and lipase levels are not specific but elevated levels or serial escalation may suggest pancreatic injury, as well as peripancreatic trauma. Correlation with imaging is mandatory. Base deficit is a frequently underused biochemical test for abdominal trauma resuscitation. Liver function tests, lactate levels, coagulation studies, creatinine kinase, and toxicology screens are also useful. Urinalysis with gross hematuria confirming renal damage, microscopic hematuria of less than 50 RBCs/HPF, or a visual inspection of blood-tinged urine is a good clinical indicator of urogenital injury.

Imaging Studies

Plain Radiography

Anteroposterior (AP) chest and pelvic radiographs are standard initial assessments of patients with multisystem blunt trauma. If the patient is unstable, no radiographs are needed in the emergency room.1,3 A radiographic marker on entry wounds of a penetrating injury may aid in determining the trajectory and path of missiles.

Focused Assessment Sonography in Trauma: Ultrasonography

Focused assessment sonography in trauma (FAST)⁷ is a well-established trauma assessment by ultrasound of the cardiac, bilateral renal, and pelvic area that has been validated in several prospective randomized studies. FAST is operator-dependent but has great sensitivity, specificity, and accuracy comparable to diagnostic peritoneal lavage (DPL) and computed tomography (CT) for assessing intra-abdominal fluid and involves no radiation exposure or contrast administration. The advantages of FAST are immediate bedside intra-abdominal visualization, its noninvasive portable nature, avoidance of transport to radiology, and ability of repeat examinations to monitor interval changes. It is performed to document fluid in the pericardial sac, hepatorenal space (Morrison’s pouch), splenorenal fossa, and pelvis (pouch of Douglas). Negative FAST results do not preclude the need for further evaluations with further CT imaging.⁸ Equivocal studies should prompt immediate evaluation with contrast-enhanced CT for determination of solid organ injury. Disadvantages of FAST are poor sensitivity in pediatric patients, interference because of bowel gas and increased adiposity, uncooperative patients, and ascites (Box 9-1).

Box 9-1

Focused Assessment Sonography in Trauma Procedure

1. A nasogastric tube is inserted before the examination, if needed, but the urinary catheter is withheld so that the distended bladder provides an acoustic window for visualization of blood in the pelvis.

2. Using a 3.5-MHz transducer, FAST surveys for blood in the pericardial sac and three dependent abdominal regions, including Morison’s pouch, splenorenal recess, and pelvis.

3. Ultrasound transmission gel is applied to the pericardial area, right and left upper quadrants, and pelvis. (The pericardial area is visualized first, so that blood in the heart can be used as a standard to set the gain appropriately for the detection of hemoperitoneum and hemopericardium.)

4. The transducer is oriented for sagittal sections and positioned in the subxiphoid region to identify the heart and examine for blood in the pericardial sac.

5. The transducer is placed in the right midaxillary line between the 11th and 12th ribs to identify the sagittal section of the liver, kidney, and diaphragm.

6. With the transducer positioned in the left posterior axillary line between the ninth and tenth ribs, the spleen and kidney are visualized.

7. The transducer is directed for a transverse section and placed 4 cm superior to the symphysis pubis. It is swept inferiorly to obtain a coronal view of the full bladder and both sides of the pelvis.

From Rozycki GS, Root HD: The diagnosis of intra-abdominal visceral injury. J Trauma 68:1019–1023, 2010.