Trauma
Question 128 of 216
A 17 year old man is carried into the Emergency Department by his friends. They tell you he has been stabbed in the abdomen. Which of the following structures is most commonly injured following stab wounds to the abdomen?
Answer:
- Most commonly injured structures in stab wounds:
- Liver (40%)
- Small bowel (30%)
- Diaphragm (20%)
- Colon (15%)
Abdominal Trauma: Types of Injury
Trauma
Last Updated: 13th February 2021
Relevant abdominal anatomy
- Anterior abdomen
- The anterior abdomen is the area between the costal margins superiorly, the inguinal ligaments and pubic symphysis inferiorly and the anterior axillary lines laterally
- Contains majority of hollow viscera
- Thoracoabdomen
- The thoracoabdomen is the area inferior to the nipple line anteriorly and the infrascapular line posteriorly and superior to the costal margins (somewhat protected by the bony thorax)
- Contains the diaphragm, liver, spleen and stomach
- Flank and Back
- The flank is the area between the anterior and posterior axillary lines from the sixth intercostal space to the iliac crest
- The back is the area located posterior to the posterior axillary lines from the tip of the scapulae to the iliac crests (musculature in the flank, back and paraspinal region acts as a partial protection from visceral injury)
- The flank and back contain the retroperitoneal space containing the abdominal aorta, inferior vena cava, most of the duodenum, pancreas, kidneys and ureters, the posterior aspect of the ascending and descending colons, and the retroperitoneal components of the pelvic cavity
- Pelvic cavity
- The pelvic cavity is the area surrounded by the pelvic bones containing the lower parts of the retroperitoneal and intraperitoneal spaces
- Contains the rectum, bladder, iliac vessels and, in females, the internal reproductive organs
Mechanism of injury
Consideration of the mechanism of injury facilitates the early identification of potential injuries, directs which diagnostic studies may be necessary for evaluation, and identifies the potential need for patient transfer.
Blunt trauma:
- Types of injury in blunt trauma include:
- Direct blow injury
- Such as contact with the lower rim of the steering wheel, bicycle or motorcycle handlebars, or an intruded door in a motor vehicle crash
- Can cause compression and crushing injuries to abdominopelvic viscera and pelvic bones; such forces deform solid and hollow organs and can cause rupture with secondary haemorrhage and contamination by visceral contents with associated peritonitis
- Shearing injury
- A form of crush injury that can result when a restraint device is worn inappropriately
- Deceleration injury
- Such as patients injured in motor vehicle crashes and who fall from significant heights;
- There is a differential movement of fixed and mobile parts of the body; examples include lacerations of the liver and spleen (both movable organs that are fixed at the sites of their supporting ligaments) or bucket handle injuries to the small bowel
- Direct blow injury
- Most commonly injured organs in blunt trauma:
- Spleen (40 - 55%)
- Liver (35 - 45%)
- Small bowel (5 - 10%)
- Retroperitoneal haemorrhage (15%)
- Patterns of injury with restraint devices in blunt trauma:
- Lap seat belt (compression and hyperflexion)
- Tear or avulsion of bucket mesentery (bucket handle)
- Rupture of small bowel or colon
- Thrombosis of iliac artery or abdominal aorta
- Chance fracture of lumbar vertebrae
- Pancreatic or duodenal injury
- Shoulder harness (submarining and compression)
- Rupture of upper abdominal viscera
- Intimal tear or thrombosis in innominate, carotid, subclavian or vertebral artery
- Fracture or dislocation of cervical spine
- Rib fractures
- Pulmonary contusion
- Airbag (contact, deceleration, flexion, hyperextension)
- Face and eye abrasions
- Cardiac injuries
- Spinal fractures
- Lap seat belt (compression and hyperflexion)
Penetrating trauma:
- Stab wounds and low-energy gunshot wounds cause tissue damage by lacerating and tearing. High-energy gunshot wounds transfer more kinetic energy, causing increased damage surrounding the track of the missile due to temporary cavitation.
- Most commonly injured structures in stab wounds:
- Liver (40%)
- Small bowel (30%)
- Diaphragm (20%)
- Colon (15%)
- Most commonly injured in gunshot wounds:
- Small bowel (50%)
- Colon (40%)
- Liver (30%)
- Abdominal vascular structures (25%)
Blast injury:
- Blast injury from explosive devices occurs through several mechanisms, including penetrating fragment wounds and blunt injuries from the patient being thrown or struck by projectiles. The treating doctor must consider the possibility of combined penetrating and blunt mechanisms in these patients.
- An individual close to the explosion may sustain primary blast injury from the force of the blast wave. A secondary blast injury may occur from debris and other objects accelerated by the blast (e.g. fragments), leading to penetrating wounds, lacerations, and contusions. A tertiary blast injury may occur from the patient being violently thrown to the ground or against other objects by the blast effect, leading to blunt musculoskeletal and other injuries.
- Patients close to the source of the explosion can incur additional injuries to the tympanic membranes, lungs, and bowel related to blast overpressure. These injuries may have delayed presentation.
- The potential for overpressure injury following an explosion should not distract the clinician from a systematic approach to identifying and treating blunt and penetrating injuries.
Specific injuries
The liver, spleen, and kidney are the organs predominantly involved following blunt trauma, although the relative incidence of hollow visceral perforation, and lumbar spinal injuries increases with improper seat-belt usage. Diagnosis of injuries to the diaphragm, duodenum, pancreas, genitourinary system, and small bowel can be difficult. Most penetrating injuries are diagnosed at laparotomy.
- Diaphragm injuries
- Blunt tears can occur in any portion of either diaphragm, although the left hemidiaphragm is most often injured. A common injury is 5 to 10 cm in length and involves the posterolateral left hemidiaphragm.
- Abnormalities on the initial chest x-ray include elevation or “blurring” of the hemidiaphragm, haemothorax, an abnormal gas shadow that obscures the hemidiaphragm, or a gastric tube positioned in the chest. However, the initial chest x-ray can be normal in a small percentage of patients.
- Suspect this diagnosis for any penetrating wound of the thoracoabdomen, and confirm it with laparotomy, thoracoscopy, or laparoscopy.
- Duodenal injuries
- Duodenal rupture is classically encountered in unrestrained drivers involved in frontal-impact motor vehicle collisions and patients who sustain direct blows to the abdomen, such as from bicycle handlebars.
- A bloody gastric aspirate or retroperitoneal air on an abdominal radiograph or CT should raise suspicion for this injury.
- An upper gastrointestinal x-ray series, double-contrast CT, or emergent laparotomy is indicated for high-risk patients.
- Pancreatic injuries
- Pancreatic injuries often result from a direct epigastric blow that compresses the pancreas against the vertebral column.
- An early normal serum amylase level does not exclude major pancreatic trauma. Conversely, the amylase level can be elevated from non-pancreatic sources.
- Double-contrast CT may not identify significant pancreatic trauma in the immediate post-injury period (up to 8 hours). It may be repeated, or other pancreatic imaging performed, if injury is suspected.
- Surgical exploration of the pancreas may be warranted following equivocal diagnostic studies.
- Genitourinary injuries
- Contusions, haematomas, and ecchymoses of the back or flank are markers of potential underlying renal injury and warrant an evaluation (CT or IVP) of the urinary tract.
- Gross haematuria is an indication for imaging the urinary tract.
- Gross haematuria and microscopic haematuria in patients with an episode of shock are markers for increased risk of renal abdominal injuries.
- An abdominal CT scan with IV contrast can document the presence and extent of a blunt renal injury, which frequently can be treated non-operatively.
- Thrombosis of the renal artery and disruption of the renal pedicle secondary to deceleration are rare injuries in which haematuria may be absent, although the patient can have severe abdominal pain. With either injury, an IVP, CT, or renal arteriogram can be useful in diagnosis.
- An anterior pelvic fracture usually is present in patients with urethral injuries.
- Urethral disruptions are divided into those above (posterior) and below (anterior) the urogenital diaphragm. A posterior urethral injury is usually associated with multisystem injuries and pelvic fractures, whereas an anterior urethral injury results from a straddle impact and can be an isolated injury.
- Hollow viscus injuries
- Blunt injury to the intestines generally results from sudden deceleration with subsequent tearing near a fixed point of attachment, particularly if the patient’s seat belt was positioned incorrectly.
- A transverse, linear ecchymosis on the abdominal wall (seat-belt sign) or lumbar distraction fracture (i.e. Chance fracture) on x-ray should alert clinicians to the possibility of intestinal injury.
- Although some patients have early abdominal pain and tenderness, the diagnosis of hollow viscus injuries can be difficult since they are not always associated with haemorrhage.
- Solid organ injuries
- Injuries to the liver, spleen, and kidney that result in shock, haemodynamic abnormality, or evidence of continuing haemorrhage are indications for urgent laparotomy.
- Solid organ injury in haemodynamically normal patients can often be managed non-operatively. Admit these patients to the hospital for careful observation, and evaluation by a surgeon is essential.
- Concomitant hollow viscus injury occurs in less than 5% of patients initially diagnosed with isolated solid organ injuries.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
