Blunt Abdominal Trauma


Author: Tracy Evans, MBA, RN, EMT-P

Epidemiology

Abdominal injuries rank third as a cause of traumatic death just after head and chest injuries. Unrecognized abdominal injuries are frequently the cause of preventable death. (ACS, 1997) Abdominal trauma results in a mortality rate of 13- 15%. The primary cause of death is hemorrhage, but in death occurring after 48 hours, sepsis is the culprit. (Wilson, 1999) Patients with multiple abdominal organ injuries (with or without an injury to another body system) have significantly higher mortality rates than those with an isolated abdominal injury. Intra-abdominal trauma is seldom a single organ injury or single system injury; therefore, patients experience the concomitant rise is morbidity and mortality. (Cardona, 1994) Approximately 20% of all traumatized patients requiring surgery sustained trauma to the abdomen.

Mechanism of Injury

The abdomen is vulnerable to injury since there is minimal bony protection for underlying organs. The vena cava, aorta, pancreas and duodenum are located retroperitoneally which provides them with increased protection. It is critical to remember that the physical examination may not reveal underlying injury, so a high index of suspicion based on mechanism of injury is key. The findings in abdominal trauma can be subtle, so serial assessments are crucial.

Blunt vs Penetrating

The most common mechanism of blunt abdominal injury is a motor vehicle crash (MVC). (Fabian, 2000) Injuries to the abdomen can result from acceleration, deceleration, or a combination of both forces. The abdominal viscera may be compressed or directly impacted. Crushing forces may compress the duodenum or the pancreas against the vertebral column. During energy transfer, abdominal structures, which are attached by either ligaments or blood vessels may be stressed at their attachment points. Pressure applied to a solid organ can both rupture a surrounding capsule and injure the parenchymal tissues.

Safety restraint devices, particularly three-point safety belts, provide significant protection, however, if they are improperly positioned, they can cause deceleration injuries to the lower abdomen.(Mason, 1994) Lap belt use has been associated with injury to the small bowel, colon and lumbar spine.(ACS, 1997) Frontal impact crashes with a bent steering wheel and broken windshield are associated with hepatic and splenic injuries as well as concomitant head and chest trauma. Depending on the side of the impact, lateral impact crashes can also damage the liver and spleen. Rear impact crashes can result in neck or abdominal injuries in unrestrained drivers who strike the steering wheel. Ejected motorcyclists may sustain pelvic fractures or intra-abdominal trauma from collisions with the handlebars or ground.

Firearms, stabbings and physical assaults are associated with penetrating abdominal trauma. The organs of the abdomen are vulnerable to penetrating injury not only through the anterior abdominal wall, but through the back, flank area and lower chest. Patients with penetrating abdominal injuries may present with single or multiple wounds. The liver, small bowel, and stomach are the most commonly injured organs from penetrating trauma.

Anatomy and Physiology

The abdominal cavity extends from the diaphragm to the pelvis and is bounded anteriorly by the abdominal wall and posteriorly by the vertebral column. The left side of the diaphragm is slightly lower than the right and may extend to the level of the fifth rib in the mammary line. The abdominal contents are located in the peritoneal cavity, retroperitoneal space, or pelvic cavity.

The abdominal structures are covered by a serous, smooth membrane called the peritoneum. The parietal peritoneum lines the abdominal wall. The visceral layer surrounds organs of the abdomen. Because the peritoneum is a smooth, lubricated layer of tissue, the viscera can move within the abdomen without friction. Mesenteries are sheets of connective tissue covered by peritoneum, and they carry blood vessels. Certain organs are surrounded by peritoneum and are suspended from the abdominal wall by mesenteries. The kidneys, pancreas, aorta, vena cava and duodenum are located in the retroperitoneal space and are partially covered by the peritoneum.  In men, the peritoneum is a closed sac, but in women the peritoneum is open at the distal ends where the fallopian tubes enter the peritoneal cavity.

Specific Organs and Injuries

 

The Liver

The liver is an encapsulated solid and extremely vascular organ weighing 3-4 pounds (1200-1600 grams)located in the right upper quadrant. The circulation through the liver is via the hepatic artery and portal vein and blood flow to the liver is approximately 30% of the total cardiac output. The liver has several major functions:

  • Detoxifies
  • Secretes Bile and Bile Salts
  • Synthesizes Prothrombin, Fibrinogen, Factors I, II, VII, IX, X
  • Vitamin K absorption
  • Metabolism of Fats, Proteins, Carbohydrates
  • Stores Iron, Vitamins A, B12 and D
  • Produces Plasma Proteins
  • Stores up to 500 ml blood

Hepatic Injuries

Because of its size and vascularity, liver injury can cause profuse hemorrhage.  Injuries can be as simple as subcapsular hemorrhages with controlled bleeding since the capsule allows the liver to tamponade bleeding, to bursting wounds that disrupt the structure of the liver and the function of the circulatory system.

Signs and symptoms of hepatic injury can include:

  • Upper right quadrant pain
  • Abdominal wall rigidity and guarding
  • Rebound tenderness
  • Loss of bowel sounds
  • Signs of hemorrhagic shock

           

The Spleen

The spleen is located in the left upper quadrant, under the diaphragm and lateral to the stomach. It is 10 to 14 cm long, 6 to 10 cm wide, 3-4 cm thick and weighs 80 to 300 grams.  The spleen receives about 5% of cardiac output (approximately 250 mL) via the splenic artery. It acts as a blood filter and reservoir for 200 ml of blood. It is also vital immunologically. As blood passes through the central arteries in the spleen, it comes into contact with the lymphocytes for antigen processing. At this time the fixed macrophages actively phagocytize the older red blood cells. If the spleen is absent, the liver must take on those functions.

Splenic Injuries

While injury to the spleen is usually caused by blunt trauma, fractures to the 10th -12th ribs are associated with penetrating damage.

Signs and symptoms of splenic injury can include:

  • Left upper quadrant pain
  • Signs of hemorrhagic shock
  • Kehr’s sign (pain in the left shoulder)
  • Abdominal wall rigidity and guarding

The Kidney

The kidneys are in the retroperitoneal space at the level of T-12 to L-3.  Anatomically, the right kidney is lower than the left because of the location of the liver.  The kidneys are surrounded by a capsule of fatty tissue and a layer of renal fascia. This fascia, along with the renal vessels hold the kidneys in position. Because they are not fixed to the abdominal wall, they move with inspiration and exhalation. The kidneys play a key role in fluid and electrolyte balance.  Besides producing urine, the kidneys help to regulate hydrogen ion, potassium, sodium, calcium, phosphorous and water balance. The kidneys also produce a hormone, erythropoietin, that is responsible for stimulating red blood cell production. A decreased in this hormone can lead to severe anemia.

Renal Injuries

The renal parenchyma can be damaged by shearing or compression forces and  cause laceration or contusion, which is the most common injury to the kidney. Renal injuries must be suspected with fractures to the posterior ribs or lumbar vertebrae. Hemorrhagic shock is not common in injury to the kidney, although rupture of the renal artery with a deceleration injury may cause hypovolemia. The is little collateral circulation to the kidney, and damage to the renal artery may lead to acute tubular necrosis and intrarenal failure.

Signs and symptoms of renal injury can include:

  • Grey-Turner’s Sign (ecchymosis over the flank)
  • Flank or abdominal tenderness
  • Hematuria
  • Cullen’s sign (peri-umbilical bruising indicative of retroperitoneal hemorrhage)

The Stomach

The stomach is in the left upper quadrant between the liver and spleen and contains acidic gastric secretions. It joins the esophagus 3 cm below the diaphragm. It is suspended in place by numerous ligaments. Stomach ruptures from blunt trauma, while relatively rare, are often fatal. Stomach injuries from penetrating trauma also carry a high mortality rate.

The Small Intestines

The small bowel is held in position by the adjacent viscera, the peritoneal membrane attachments to the posterior wall and ligaments. It is approximately 21 feet (7 meters) in length and is divided into 3 sections:

Duodenum: The duodenum is the first portion of the small intestine. It is C-shaped and about 25 cm in length. Only the first portion of the duodenum is located in the abdominal cavity, with the remaining 75% located in the retroperitoneal space. Because there is little absorption in the stomach, the duodenum receives almost all of the ingested food as well as saliva, gastric secretions, bile, and pancreatic juice. In fact, 3-6 liters of fluid pass through the duodenum each day.  Duodenal injuries are often caused by blunt trauma crushing the duodenum against the vertebrae or causing a blow-out of the loop. The mortality rate of duodenal trauma is 30%. (Wilson, 1999).

Jejunum: The jejunum lies in the umbilical region of the abdomen. Most absorption takes place in the jejunum, except for bile salts and Vitamin B12.

Ileum: The terminal portion of the small intestine is the ileum. Absorption of bile salts and Vitamin B12 occurs in the ileum. Most fluid shifts back into the circulatory system in the jejunum and ileum, before entering the colon.

The Colon

The colon is located in all four quadrants of the abdomen and is thus at an increased risk for injury from penetrating trauma. Blood supply for the colon is rich and comes from the inferior and superior mesenteric, which branch directly off the aorta. Blunt trauma to the colon or rectum is unusual. (Wilson, 1999) It does occur, the transverse colon is most likely injured.

The Urinary Tract

The bladder is a membranous sac that collects urine. The empty bladder is protected by the symphysis pubis, but when full, it rises above the protective cover. The urethra is a canal that allows for the passage of urine from the bladder to the urinary meatus.  The male urethra is longer and the prostate gland surrounds the neck of the bladder and part of the urethra.

Bladder and Urethral Trauma

Most bladder injuries are the result of blunt trauma. Bladder ruptures often accompany pelvic trauma. Urine leaking into the abdominal cavity is problematic for the patient’s recovery. The male urethra is longer, and thus more susceptible to trauma. Again, pelvic fractures are associated with urethral injuries in males and females.

Signs and Symptoms of bladder or urethral trauma include:

  • Suprapubic pain
  • Abdominal wall rigidity and guarding
  • Blood at the meatus
  • Rebound tenderness
  • Urge but inability to urinate
  • Hematuria
  • Blood in or scrotal swelling

Assessment findings: what do they mean?

Interactive learning: Click on the areas below to explore common diagnoses and patient complaints.
Flash file by Colleen Hayes, MBA, RN, EMT-P

Pain

Pain, rigidity, guarding or spasm of the abdominal musculature are classic signs of intra-abdominal injury or illness. Rebound tenderness and guarding of the abdominal muscles are caused by sudden movement of irritated peritoneal membranes against the abdominal wall. Irritation may be caused by the presence of free blood or gastric contents in the peritoneal cavity. Damage to the pancreas and duodenum are related to hemorrhage in the area and the effect of active enzymes on their surrounding tissues. The resultant "chemical peritonitis" from the enzymes released into the retroperitoneum and the significant tissue swelling may not appear as signs and symptoms for several hours after the injury (Marx, 1997). The patient with pancreatic and duodenal injury may also complain of diffuse abdominal tenderness and pain radiating from the epigastric area to the back.

Interactive learning: Use yopur mouse to roll over the colored areas to learn more about referred pain patterns.
Flash file by Colleen Hayes, MBA, RN, EMT-P

Pain can referred to other areas of the body. An example is the referred shoulder pain called Kehr’s sign which is associated with splenic rupture. The blood that collects under the diaphragm causes irritation of the phrenic nerve which innervates the diaphragm. The pain is perceived along the course of the nerve and is commonly located in the left subscapular region. Pain referred to the testicles may indicate a duodenal injury.

 

 


More interactive learning: Click on the terms on the left to learn more about advanced abdominal pain assessment. Flash file by Colleen Hayes, MBA, RN, EMT-P

Hypotension and Blood Loss

Injuries to the organs or abdominal blood vessels may lead to extensive hemorrhage. Some abdominal organs are semi-fixed by ligaments, such as the mesenteric attachments of the intestines or the falciform ligament and ligamentum teres of the liver. When the organs are stressed at their points of attachment, tears can occur at the point where the vessel enters the organ. The spleen and liver have both rich blood supply and a store of 200-500 ml or blood. Rapid loss of blood from their parenchymal or vascular structures can occur. Because they are encapsulated, compression of the abdomen may rapidly increase pressure in the capsule, resulting in rupture and hemorrhage. Bleeding from the organs in the peritoneal space is generally confined to the cavity, where as bleeding from the retroperitoneal cavity may cause bleeding in that cavity, which is more difficult to evaluate. Thus a high index of suspicion from the biomechanics of the injury are critical to improving outcome.

Hypoactive Bowel Sounds

Following abdominal injury, bowel sounds can be hypoactive. Blood in the abdominal cavity from direct injury can decrease peristaltic activity.

Conclusion

Abdominal trauma can result in serious injury to the internal organs.  The more organs involved the higher the likelihood of major complications and death. The degree of injury to the abdomen is related to the degree of the force applied, however, in blunt abdominal trauma the true extent of the injury may not be immediately apparent to the EMS provider. This is demonstrated over and over again by dozens of case studies illustrating that about  40% of all blunt abdominal trauma cases are missed until the patient decompensates.  Maintain a high index of suspicion when the mechanism of injury suggests that abdominal trauma is likely. Report your findings about the mechanism of injury to the Emergency department staff so they can share your level of suspicion. The details surrounding the circumstances of the incident plus your physical assessment findings are invaluable and my make the difference in the care your patient ultimately receives.

References

  1. American College of Surgeons Committee on Trauma. (1997). Abdominal trauma. In: Advanced Trauma Life Support Program for Doctors (Instructor Course manual). 6th ed. Chicago: American College of Surgeons Committee on Trauma.
  2. Fabian, T. C. , Croce, M. A. (2000). Abdominal trauma, including indications for celiotomy. In: Mattox, K.L. Feliciano D.V. Moore, E.E. 4th ed. Trauma. New York: McGraw-Hill.
  3. Mason, P.J. (1994). Abdominal trauma. In: Cardona, VD, Hurd, P.D, et al. Trauma Nursing: From Resuscitation Through Rehabilitation. 2nd. Philadelphia: WB Saunders.
  4. Marx, J. A. (1997). Abdominal trauma. In Rosen P. Barkin R.M. et al. Emergency Medicine: Concepts and Clinical Practice. 4th ed. St Louis: Mosby-Year Book.
  5. Wilson, R. F. (1999). Handbook of Trauma: Pitfalls and Pearls. Philadelphia: Lippincott Williams and Wilkins.