Introduction

Abdominal trauma is a significant cause of morbidity and mortality in the United States, with abdominal injuries occurring in approximately 1% of all trauma patients.¹ However, abdominal trauma accounts for over 20% of all trauma-related deaths.² Abdominal and flank trauma may result in direct injury to a number of important structures, including the liver, spleen, kidneys, diaphragm, pancreas, and intestines. Unfortunately, the diagnosis may be challenging, as patients often present with multiple other injuries and may not be able to provide a reliable history or examination.³

Causes

• 
  

  Blunt abdominal and flank trauma can occur from a number of causes. One large, multicenter study found that motor vehicle collisions (MVC) were responsible for 81% of cases, followed by falls in 9% of cases, and assault in 7% of cases.³

  
  
• 
  

  Penetrating abdominal and flank trauma is divided into two categories: low-energy (i.e. stab wounds) and high-energy (i.e. gunshot wounds). While stab wounds are three times more common, gunshot wounds are responsible for 90% of the mortality from penetrating trauma.⁴ Gunshot wounds are further classified into low-velocity (i.e. handgun and low-caliber rifles) and high-velocity (i.e. military and hunting rifles) injuries. High-velocity injuries are associated with more damage. The exception to this is shotgun injuries, which can cause substantial damage at close range, despite being a low-velocity weapon.⁵

Anatomy

• 
  

  The abdominal compartment extends from the diaphragm to the pelvis and includes both intraperitoneal and retroperitoneal organs. Because the rib cage extends below the diaphragm, upper abdominal organs may overlap with the chest compartment (referred to as the thoraco-abdominal area).

  
  
• 
  

  The flank is the area between the anterior and posterior axillary lines extending from the sixth intercostal space to the iliac crest.

  
  
• 
  

  The most common organs injured include the spleen, liver, kidney, small bowel, and diaphragm.

  
  
• 
  

  The liver, spleen, small bowel, transverse colon, and diaphragm are intraperitoneal, while the kidneys, adrenal glands, ascending colon, and descending colon are located in the retroperitoneum. The pancreas contains both intraperitoneal and retroperitoneal portions. Injuries that occur within the peritoneal cavity can result in significant blood loss, as the abdomen can store a large amount of blood. The retroperitoneum space is more limited; therefore, injuries within the retroperitoneal compartment are more contained, resulting in decreased blood loss compared with the peritoneum.

Pathophysiology

• 
  

  Penetrating trauma may remain superficial or traverse multiple tissue planes. While a stab wound follows a relatively direct course, gunshot wounds may alter their trajectory after entering the skin. Therefore, one cannot assume that the trajectory was linear between both skin wounds, and it is important to consider peritoneal involvement in any gunshot wound.

  
  
• 
  

  Blunt trauma occurs from either direct impact to a specific organ or when there is a sudden deceleration which exceeds the elasticity of the organ, resulting in tearing of the organ or supporting structures.

  
  
• 
  

  Children are at increased risk of injury when compared to adults, because their abdomen is less well-protected. Children have thinner abdominal musculature, so it is easier to compress their abdominal organs against their posterior vertebrae. Additionally, their ribs are more elastic, resulting in decreased protection of their liver and spleen.

  
  
• 
  

  Pregnant women are relatively protected from abdominal organ injury by their gravid uterus. However, this is balanced by potential injuries to the uterus (e.g. placental abruption, uterine rupture), as discussed in Chapter 4.

  
  
• 
  

  The risk of injury to a specific organ is related to its size and structure. While the duodenum is smaller than other intraabdominal organs, direct trauma from bicycle handlebars or a misplaced seatbelt can cause significant injury due to its relatively unprotected location. Similarly, injuries to the spleen are more common after blunt trauma because it is less elastic than the other organs. This is particularly problematic in patients with mononucleosis, wherein the spleen becomes enlarged and can have a significant injury despite relatively minimal trauma.

History

• 
  

  Obtain as much information as possible from the emergency medical services (EMS) personnel. Important information includes the initial vital signs, patient’s course, suspected injuries, estimated blood loss at the scene, and any treatments received in transit.

  
  
• 
  

  Additional information from the patient or EMS personnel should include the mechanism, other injuries, allergies, medications, past medical and surgical history, and the last time the patient had anything to eat or drink.

  
  
• 
  

  If the injury was due to an MVC, it is valuable to know the speed of the patient’s and other driver’s vehicles, condition and drivability of the vehicle, airbag deployment, windshield condition, seatbelt use, and condition of the other passengers and drivers.

  
  
• 
  

  If the injury was due to a fall, the approximate height of the fall, what surface the patient fell on, point of contact on the patient’s body, and any areas of contact prior to striking the ground are all useful historical information.

  
  
• 
  

  If the patient was stabbed with an object, it is important to know what type of object, the shape of the object, the length of the object, position of the patient during the injury, and all locations where contact was made, regardless of how significant the injury was felt to be.

Examination

• 
  

  Blood pressure and heart rate are the most important vital signs when assessing for significant intra-abdominal injury. Hypotension and tachycardia should raise the concern for significant blood loss. However, even transient hypotension is associated with worse outcomes. Importantly, relatively bradycardia may be present in up to 44% of trauma patients and is an independent risk factor for mortality.⁶ Additionally, while abnormal vital signs should raise one’s concern of intra-abdominal injury, normal vital signs do not exclude significant injury.

  
  
• 
  

  After completion of the primary survey, the secondary survey of the abdomen should include assessment for external abrasions or ecchymoses, as well as abdominal tenderness, guarding, rigidity, or peritoneal signs. Increasing abdominal distension or peritonitis should increase one’s concern for ongoing intraperitoneal bleeding.

  
  
• 
  

  Alcohol, drugs, head injury, or significant distracting injuries may reduce the patient’s ability to identify abdominal pain or tenderness, with one study suggesting that one-fifth of patients with positive findings on CT for intraabdominal injury did not have tenderness on examination.³ Additional studies have found that 25–58% of patients with small bowel or mesenteric injury do not have abdominal tenderness.^{7, 8} A separate study found that 3% of patients with splenic injury had isolated left rib pain without abdominal pain.⁹ Therefore, one must be vigilant for intraabdominal injuries and should consider advanced imaging or serial abdominal examinations among patients with concerning symptoms or distracting injuries, despite the absence of abdominal pain.

  
  
• 
  

  It is important to consider the location of the ecchymosis or pain, as this can help suggest the underlying injury. For example, blunt trauma to the right flank should raise one’s suspicion of renal or liver injury, while bruising over the epigastric area may suggest potential underlying pancreatic or duodenal injury. Of note, the presence of a “seat belt mark” has been associated with an 8-fold increase in the risk of intra-abdominal injury (Figure 15.1).¹⁰ Cullen’s sign (periumbilical ecchymosis) and Turner’s sign (flank ecchymosis) may suggest retroperitoneal hemorrhage, but are uncommon and often late findings.^{11, 12} Kehr’s sign (left shoulder pain referred from diaphragmatic irritation) suggests potential splenic injury.¹³

  
  
• 
  

  Patients should be fully exposed, and a thorough skin examination should be performed, including all skin folds, the axillae, and the inguinal area.

  
  
• 
  

  In patients with stab wounds to the anterior abdomen, local wound exploration can be performed to determine whether the injury extends into the peritoneum.¹⁴ However, gunshot wounds or wounds from a sharp and narrow instrument (e.g. icepick) are poor candidates for local exploration (Figure 15.2).

  
  
• 
  

  While gross blood or palpable subcutaneous emphysema on the rectal exam can suggest intra-abdominal injury, these findings are uncommon, and other clinical indicators are typically present prior to these finding. Therefore, many experts recommend deferring or eliminating this examination.^15–17 The exception to this is penetrating trauma to the rectal area or concern for cauda equina syndrome.

(A) The presence of this sign is a marker of significant intra-abdominal injury.

(B) Intraoperative photograph of the same patient showing perforation of the small bowel

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 15.1 Seatbelt mark in a car accident patient.

Figure 15.2

(A) Stab wound to the abdomen with impaled knife. These objects should only be removed in the operating room. Only about 50% of anterior abdominal stab wounds have significant injuries requiring surgical repair.

(B) Low-velocity gunshot wound. About 75% of these wounds have significant injuries requiring surgical repair

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Differential Diagnosis

Penetrating abdominal trauma may result in injury to any intraperitoneal or retroperitoneal structure. The liver, small intestine, and colon are the most common injuries from penetrating trauma.⁴ While abdominal vasculature is not commonly injured as a result of stab wounds, it is the fourth most common injury among gunshot wounds. Blunt abdominal trauma can result in injury to the liver, spleen, intestines, pancreas, and diaphragm. Splenic and hepatic injuries represent the majority of intra-abdominal injuries from blunt trauma. Flank trauma can involve the kidney or colon.

Hepatic Injury

Hepatic injury typically presents with right upper quadrant or right flank pain. Stable patients are typically managed non-operatively, while unstable patients require operative management. One study of blunt hepatic injury had a 100% salvage rate with non-operative management (Figures 15.3 and 15.4).¹⁸ Table 15.1 includes the American Association of Surgery for Trauma (AAST) grading criteria for liver injury.¹⁹

Figure 15.3 CT scans of various grades of blunt liver trauma: (A) grade I, (B) grade II, (C) grade III, (D) grade IV

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 15.4 Many penetrating liver injuries can safely be managed nonoperatively, provided the patient is hemodynamically stable and has no peritonitis. A CT scan should always be performed: (A) CT scan of stab wound and (B, C) gunshot wounds to the liver successfully managed nonoperatively

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Table 15.1 AAST liver injury grading criteria¹⁹

Grade	Type	Injury Description
I	Hematoma	Subcapsular, <10% surface area
	Laceration	Capsular tear, <1 cm parenchymal depth
II	Hematoma	Subcapsular, 10–50% surface area intraparenchymal <10 cm in diameter
	Laceration	Capsular tear 1–3 parenchymal depth, <10 cm in length
III	Hematoma	Subcapsular, >50% surface area of ruptured subcapsular or parenchymal hematoma; intraparenchymal hematoma >10 cm or expanding
	Laceration	>3 cm parenchymal depth
IV	Laceration	Parenchymal disruption involving 25–75% hepatic lobe or 1–3 Couinaud’s segments
V	Laceration	Parenchymal disruption involving >75% of hepatic lobe or >3 Couinaud’s segments within a single lobe
	Vascular	Juxtahepatic venous injuries (i.e. retrohepatic vena cava/central major hepatic veins)
VI	Vascular	Hepatic avulsion

Splenic Injury

Splenic injury occurs most commonly with left upper quadrant or left flank trauma but can occur in association with deceleration injuries. Patients present with left upper quadrant pain, which may be associated with left shoulder pain referred from the phrenic nerve. Stable patients may be managed non-operatively with consideration for angiographic embolization, while unstable patients require operative management (Figures 15.5 and 15.6). One study of the non-operative management of blunt splenic injuries had a 90% overall salvage rate, including an 80% salvage rate among grade 4 and 5 injuries.²⁰ Table 15.2 includes the AAST grading criteria for splenic injury.¹⁹

Figure 15.5

(A) Abdominal CT with a grade IV spleen injury.

(B) Surgical specimen of the removed ruptured spleen

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 15.6

(A) Gunshot wound to spleen with extensive damage requiring emergency splenectomy.

(B) Low-grade splenic injuries due to a stab wound

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Table 15.2 AAST splenic injury grading criteria¹⁹

Grade	Type	Injury Description
I	Hematoma	Subcapsular, <10% surface area
	Laceration	Capsular tear, <1 cm parenchymal depth
II	Hematoma	Subcapsular, 10–50% surface area; intraparenchymal, <5 cm in diameter
	Laceration	Capsular tear, 1–3 cm parenchymal depth that does not involve a trabecular vessel
III	Hematoma	Subcapsular, >50% surface area or expanding; ruptured subcapsular or parenchymal hematoma; intraparenchymal hematoma ≥5 cm or expanding
	Laceration	>3 cm parenchymal depth or involving trabecular vessels
IV	Laceration	Laceration involving segmental or hilar vessels producing major devascularization (>25% of spleen)
V	Laceration	Completely shattered spleen
	Vascular	Hilar vascular injury with devascularized spleen

Duodenal Injury

These injuries are commonly associated with blunt trauma to the upper abdomen. Patients with duodenal perforations will present with severe abdominal pain and tenderness immediately after the trauma (Figure 15.7). However, patients with duodenal hematoma are often minimally symptomatic for the first several days and may present up to a week later with onset of symptoms. Patients typically present with progressively worsening abdominal pain associated with vomiting and decreased oral intake.

(A) CT demonstrates duodenal wall thickening with intramural air.

(B) Intraoperative appearance of duodenal perforation

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 15.7 Blunt trauma to duodenum.

Pancreatic Injury

Pancreatic injuries usually present with epigastric pain occurring hours after the initial injury. They may also demonstrate Cullen’s or Turner’s signs if they are complicated by a significant retroperitoneal hemorrhage (Figure 15.8). Patients are at risk of significant intravascular fluid depletion due to third spacing, thought this is often delayed by hours to days.

Figure 15.8

(A) CT scan demonstrating distal pancreatic transection (circle).

(B) CT scan shows distal pancreatic injury (small circle) and no contrast uptake by the left kidney, due to thrombosis of the left renal artery (large circle)

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Renal Injury

Renal injury can occur from either a blunt or penetrating mechanism and is associated with flank pain and hematuria. Patients with penetrating injury in this region should receive a CT, while blunt trauma patients should receive a CT if there is gross hematuria or a significant deceleration injury (Figures 15.9 and 15.10).^{23, 24} Table 15.3 includes the AAST grading criteria for renal injury.²⁵ Treatment may involve either angiographic or surgical repair. The need for surgical repair and nephrectomy is directly correlated with the grade of renal injury. One large retrospective study found that grade I injuries had 0% risk of surgery or nephrectomy, while 93% of grade V injuries required surgery and 86% required a nephrectomy.²⁶

Figure 15.9

(A) CT scan shows a severe right kidney injury with a large surrounding hematoma.

(B) Intraoperative appearance of the renal hematoma

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Figure 15.10 Gunshot injury to kidney. (A, B) CT scan shows severe injury and a large perinephric hematoma. A nephrectomy was performed. (C) Note the complete transection of the kidney

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Table 15.3 AAST renal injury grading criteria²⁵

Grade	Type	Injury Description
I	Contusion	Microscopic or gross hematuria, urologic studies normal
	Hematoma	Subcapsular, nonexpanding without parenchymal laceration
II	Hematoma	Nonexpanding perirenal hematoma confirmed to renal retroperitoneum
	Laceration	<1.0 cm parenchymal depth of renal cortex without urinary extravasation
III	Laceration	>1.0 cm parenchymal depth of renal cortex without collecting system rupture or urinary extravasation
IV	Laceration	Parenchymal laceration extending through renal cortex, medulla, and collecting system
	Vascular	Main renal artery or vein injury with contained hemorrhage
V	Laceration	Completely shattered kidney
	Vascular	Avulsion of renal hilum which devascularizes kidney

Evaluation

• 
  

  Initial evaluation should include a primary survey and extended focused assessment with sonography in trauma (E-FAST) examination.²⁷ Two large-bore intravenous catheters should be inserted, and the patient should be placed on a cardiorespiratory monitor with continuous pulse oximetry.

  
  
• 
  

  Once this has been completed, a focused secondary examination should be performed as outlined above.

Laboratory Testing

• 
  

  Routine laboratory testing is rarely helpful in the initial evaluation of trauma patients.²⁸ As a result, some experts have recommended ordering laboratory testing only when a specific clinical need is present.^29–32 Multiple studies have demonstrated a significant cost saving without adverse events by following this strategy.^{31, 32}

  
  
• 
  

  All patients should receive a bedside glucose test, and all women of childbearing potential should receive a pregnancy test. All pregnant women with abdominal trauma should also have their Rh antibody status determined.

  
  
• 
  

  If additional laboratory testing is indicated, it will often include a complete blood count, basic metabolic panel, liver function testing, lipase, coagulation profile, lactate, and blood type and screen.

  
  
• 
  

  Urinalysis should be obtained in all patients with blunt trauma to the abdomen or flank.³³ Gross hematuria suggests an injury to the genitourinary tract and warrants further evaluation.^{23, 33, 34} Microscopic hematuria is a sign of mild renal injury and does not require further treatment in a stable patient without a significant deceleration injury.^{23, 33, 34} Because deceleration injuries can be associated with injury to the renal pedicle, further imaging or evaluation is recommended in this patient group if only microscopic hematuria is present.³³

Imaging

Ultrasound (US)

• 
  

  The E-FAST examination is recommended for all trauma patients with a significant mechanism of injury as an initial screening test. Studies have demonstrated that it is highly accurate for intraperitoneal fluid and can be completed in 2–3 minutes.^{35, 36}

  
  
• 
  

  The E-FAST examination contains six views: right upper quadrant (i.e. Morison’s pouch), left upper quadrant, suprapubic (i.e. pouch of Douglas), subxiphoid, and bilateral lung fields. Because the bladder provides the sonographic window for the suprapubic view, it is important to perform this prior to Foley placement. If a Foley catheter is already in place, sterile saline may be instilled into the bladder to facilitate visualization.

  
  
• 
  

  The presence of intraperitoneal fluid in an unstable patient is an indication for operative intervention (Figure 15.11). Importantly, in patients with major pelvic trauma and potential bladder rupture, diagnostic peritoneal aspiration may be needed to determine whether the fluid is blood or urine.³⁷

  
  
• 
  

  The presence of free fluid in a stable trauma patient should be followed immediately by a CT to identify the type of injury and the need for operative intervention. However, the absence of free fluid does not preclude the need for additional imaging or evaluation, and this should be made on a case-by-case basis in conjunction with the clinical examination.

  
  
• 
  

  The major limitation of ultrasound is its inability to evaluate solid organ injury. While US demonstrates excellent accuracy for hemoperitoneum, it has limited accuracy for hepatic or splenic injury and is not able to diagnose diaphragmatic or intestinal injury.³⁸ Additionally, US is not recommended as the primary imaging modality for renal injuries, as it has been demonstrated to miss up to 78% of renal injuries.^{33, 39}

Figure 15.11

(A) Normal FAST: right upper quadrant window depicts liver and right kidney with no free fluid (K, kidney; L, liver).

(B) Open diagnostic peritoneal lavage/aspiration technique. This technique is rarely used.

(C) FAST exam with free fluid between liver and kidney (arrow)

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition, illustration in (B) by Alexis Demetriades)

Diagnostic Peritoneal Lavage (DPL)

• 
  

  While DPL was previously a common technique in the evaluation of trauma patients (Figure 15.12), it has become less common as CT imaging quality has improved and US is increasingly available in most EDs.

  
  
• 
  

  DPL is highly accurate for the diagnosis of hemoperitoneum and organ injury in blunt trauma.^63–65 For penetrating wounds, DPL is highly accurate for peritoneal penetration, but is unfortunately less accurate for organ injury in the absence of gross blood or enteric contents. One multicenter study found that DPL performed as well as admission and serial examinations in a population with penetrating abdominal wounds.⁶⁶

  
  
• 
  

  DPL has several disadvantages, which include that it is invasive, does not identify which organ is injured, and cannot evaluate the retroperitoneum. Additionally, the non-therapeutic laparotomy rate for blunt abdominal trauma has been reported to be as high as 35%.⁶⁷

  
  
• 
  

  The following DPL findings are suggestive of intraperitoneal injury: 10 mL gross blood on initial aspiration, >500/mm³ white blood cells, >100,000/mm³ red blood cells, or the presence of enteric or vegetable matter.⁶⁸

Figure 15.12 Aspiration of gross blood from catheter during DPA

(reproduced with permission from Color Atlas of Emergency Trauma, Second Edition)

Management

• 
  

  Hypotensive patients should receive intravenous fluids followed by packed red blood cells (PRBCs) when available. Women of child-bearing potential should receive type O-negative blood, while all other patients should receive type O-positive blood. For patients who require massive transfusion (defined as 10 or more units of PRBCs in 24 hours), it is recommended that they receive plasma, platelets, and PRBCs in a 1:1:1 ratio (see Chapter 3).^{69, 70}

  
  
• 
  

  For patients with penetrating trauma, one should consider permissive hypotension (i.e. restricted fluid resuscitation) until source control is performed (see Chapter 3).^{71, 72}

  
  
• 
  

  Patients with evidence of significant intra-abdominal injury (e.g. evisceration, gross blood per rectum, hematemesis), as well as unstable patients with evidence of significant intraperitoneal injury by CT or ultrasound, should be taken directly to the operating room for surgical repair. Delay in operative repair is associated with worse outcomes, with one study finding that a 10-minute delay to the operating room for gunshot wounds was associated with a three-fold increase in mortality.⁷³

  
  
• 
  

  Stable patients with stab wounds or low-velocity gunshot wounds to the abdomen should receive a CT of the abdomen and pelvis. If the small bowel or diaphragm is involved, the patient should undergo operative repair. However, isolated peritoneal injury may be managed non-operatively with serial abdominal examinations.^74–77

  
  
• 
  

  Stable patients with blunt abdominal trauma and concern for intra-abdominal injury should receive a CT of the abdomen and pelvis or serial abdominal examinations.

  
  
• 
  

  Patients with open wounds or lacerations should receive tetanus vaccination if their immunizations are not up-to-date.

Pitfalls in Abdominal and Flank Trauma

1. 
   

   • Do not underestimate the mechanism of injury. Patients can have significant intraperitoneal injury despite normal vital signs.

   
   
2. 
   

   • Patients must be undressed and the skin fully examined to identify any and all potential injuries.

   
   
3. 
   

   • It is important to account for all bullets in penetrating trauma and consider intravascular migration if not accounted for.

   
   
4. 
   

   • The absence of abdominal pain does not exclude intra-abdominal injury.

   
   
5. 
   

   • CT may miss injuries to the diaphragm, small bowel, or pancreas.

   
   
6. 
   

   • Unstable patients should not be sent to CT.