PENETRATING ABDOMINAL TRAUMA

Introduction 

In Europe, the majority of abdominal injuries are caused by blunt trauma, mostly secondary to traffic accidents, falls and interpersonal violence. Of penetrating injuries, gunshot wounds dominate in the United States whereas stab wounds are more common in Finland and South Africa, for example. A patient may also have and internal abdominal organ injury even if the stab or gunshot inlet wound is outside the anterior abdominal area, such as in the back, flanks, buttocks, perineum, upper thighs, lower chest or arm pits.

Abdominal gunshot wounds are very often associated with internal organ injuries. In anterior abdominal gunshot wounds, the risk of organ injury is about 90%, and in gunshot wounds of the flanks or back about 40%. In contrast, anterior abdominal stab wounds are associated with a significant organ injury in only about 40%, flank wounds in 20-30%, and stab wounds of the back in 7-15%. In addition, only about 5% of patients with abdominal stab wounds have more than two organ injuries, whereas the corresponding frequency for abdominal gunshot wounds is about 40%.

The frequency of organ injuries in penetrating injuries depend mainly on the location and size of the organs, and is summarized in Table 1. 

Table 1. Frequency of organ injuries (%) in abdominal trauma (collective series from several reports)

An abdominal injury associated with significant internal bleeding usually from abdominal vascular or liver injuries, requires accurate early assessment and rapid transportation for urgent surgical intervention. A perforation in the gastrointestinal tract will eventually cause peritonitis with significant abdominal tenderness and guarding, but the early diagnosis of an intestinal injury can be very challenging before the onset of clinical peritonitis. Also injuries of the biliary or urinary tract can be initially silent and remain undiagnosed during initial assessment. Mesenteric injuries cause usually some degree of bleeding but can stop spontaneously. A large mesenteric tear may result in intestinal necrosis and perforation usually diagnosed during laparotomy. A pancreatic injury can remain initially silent, and manifest after several days, weeks or even months as pancreatic fistula, abscess or pseudocyst. A diaphragmatic injury is usually asymptomatic unless it is associated with herniation of abdominal contents into the thorax, especially on the left side. It can also manifest as diaphragmatic hernia, sometimes months or years after the initial trauma.

Clinical presentation 

A typical penetrating abdominal trauma patients is a young or middle-aged male who is under the influence of alcohol. In a recent Finnish study of 209 patients with abdominal stab wounds, the age varied from 15 to 67 (mean 36) years, 84% were male, 21% of the wounds were self-inflicted and 82% of the patients were under the influence of alcohol. The most common locations of the stab wounds were left (26%) and right (30%) upper quadrants. Shock on admission was present in 14% and diffuse peritoneal tenderness in 20%.

Prehospital management of severely injured patients 

The aim of prehospital management in severely injured multitrauma patients is to do an initial survey with life-saving procedures according to a predefined system (such as ATLS for example). After securing the airways (cervical spine control) and adequate ventilation, a possible hypovolemic shock should be managed according to local guidelines. In patients with penetrating torso injury and short evacuation time, aggressive fluid resuscitation is probably not indicated in order to reduce the risk of excessive or recurrent bleeding from internal injuries before definitive surgical control. A palpable pulse and a systolic blood pressure of 60-80 mmHg are used in some centers as guidelines for fluid resuscitation during transport.

Penetrating injuries should be exposed sufficiently in the field to evaluate potential injuries, and to compress profusely bleeding wounds. Conscious patients can usually self determine the most adequate transport position, whereas unconscious, unintubated patients should be transported lying on their side with good airway control. A retained stabbing implement should not be removed in the field but secured in place with heavy bandages and dressings.

A thoracoabdominal penetrating injury can cause a hemo- or pneumothorax. If the initial clinical assessment suggests the development of a tension pneumothorax, this should be treated at least with needle thoracocentesis before transportation. The management of pericardial tamponade in the field is challenging and could unnecessarily delay an urgent transport.

Patients with signs of significant internal hemorrhage require urgent transfer to a surgical unit. Intravenous access is secured and fluid resuscitation started but these maneuvers should cause minimal delay. Prehospital emergency thoracotomy is not recommended.

Even in  urgent situations, any information about the trauma mechanism, time of injury and patient?s initial condition and treatment is important and should be recorded and transferred to the admitting hospital.

Investigations during admission

In hemodynamically stable patients, history and physical examination are the cornerstones of initial management during admission. A systematic approach and complete exposure of the patient are important during secondary survey for all injuries at the hospital emergency room. The location of stab or gunshot wounds in fully exposed patients are recorded and the potential organ injuries based on the depth and trajectory of the penetrating object are assessed.

In stable patients, abdominal palpation is the most important clinical examination. Generalized tenderness and guarding suggest a clinically significant internal organ injury requiring surgical treatment. Bowel sounds may initially be present, even in patients with bowel perforation. The presence of bowel content in the wound, or blood seen in the stomach content or during rectal examination suggest strongly the presence of a perforation in the gastrointestinal tract.

As a part of general physical examination, breathing sounds are examined. Missing breathing sounds or even sometimes bowel sounds heard from the chest could be caused by a diaphragmatic rupture. Palpation of the femoral arterial pulses and the examination of motor and sensory functions in the lower extremities are important to detect possible vascular or spinal injuries. Hematuria, blood at the tip of urethra, or the inability to insert a urinary catheter could be a sign of a urinary tract injury. A rectal examination for blood completes the physical examination. A nasogastric tube and urinary catheter are usually inserted during the secondary survey.

Laboratory investigations should only be ordered to answer a specific question or need. Blood type and cross match, blood hemoglobin level, serum amylase level and test for microscopic hematuria are usually taken routinely at the Meilahti hospital in Helsinki. Hemoglobin or amylase levels might be initially normal in the presence of bleeding or pancreatic injury, respectively, and should be repeated within few hours.

There is no single radiological investigation which would detect or exclude all possible abdominal organ injuries. Plain chest or abdominal X-rays could reveal (in addition to a simultaneous thoracic injury) a diaphragmatic injury (bowel loops or nasogastric tube in the chest) or a GI-tract perforation (air in the peritoneal cavity). Abdominal ultrasonography is accurate in detecting intraperitoneal fluid (blood), and is very important especially in unstable patients to rapidly locate the site of bleeding. Its ability to assess specific organ injuries and their severity, however, is limited.

Contrast enhanced computed tomography is the most accurate method today to assess organ injuries in stable patients. The presence and severity of liver, kidney and splenic injuries are easily noted, but injuries to the hollow organs, pancreas and diaphragm can be missed during initial CT scan. Contrast studies of specific organs, such as the stomach, duodenum, urinary bladder and lower colorectal area can be used in selected patients. In patients not requiring early surgery for bleeding, angiograms and other vascular diagnostic methods can be used to exclude intimal tears and other vascular injuries, and be used to embolize bleeding solid organ injuries.

Diagnostic peritoneal lavage (DPL) has been previously widely used, especially in the United States but it has been partially replaced by other methods such as ultrasonography. DPL is cheap, easy to perform and relatively rapid, but sometimes oversensitive to small amounts of blood after penetrating injuries causing only minor injuries to the abdominal wall or omentum, for example. Emergency gastrointestinal endoscopies are rarely used in trauma patients, but can be used in selected cases to detect an upper- or lower GI tract injury. If logistical obstacles could be overcome, ERCP would be an ideal examination to exclude and even treat in some cases an injury to the pancreatic or biliary duct.

Diagnostic laparoscopy (and thoracoscopy in thoracoabdominal injuries) has been used to evaluate penetrating abdominal trauma. Currently, it is most useful in excluding occult diaphragmatic injuries in patients with penetrating injuries to the left lower chest area. 

Treatment

All patients with penetrating abdominal injuries causing potential organ lesions should be evaluated in a surgical unit with adequate laboratory, radiological, intensive care and operative facilities, and all patients should be transferred to these units as soon as possible after the necessary first aid. A doctor should accompany unstable patients and patients being transferred over a distance. 

In a critically ill patient, primary assessment and life-saving measures should be performed rapidly, and the need for an urgent emergency procedure should be evaluated upon arrival to the hospital. If necessary, a massive hemoperitoneum can be diagnosed rapidly with an abdominal ultrasonography (FAST) performed at the Emergency Room. 

Regardless of the trauma mechanism, all abdominal trauma patients with significant intra-abdominal hemorrhage, generalized peritonitis or radiologically verified organ injury requiring surgical repair (perforations of the GI tract,  isolated biliary or urinary tract lesions not amenable to endoscopic treatment, liver or spleen injuries requiring multiple blood transfusions, kidney lacerations extending to the collection system, diaphragmatic rupture, pancreatic rupture involving the main pancreatic duct, and major vascular injuries, for example) should undergo an early laparotomy. In addition, patients with undetermined lesions getting worse during follow up require often an early diagnostic laparotomy. 

Except in very busy trauma centers with a lot of experience in nonoperative or expectant management, all abdominal gunshot wounds and those stab wounds where peritoneal penetration has been verified (omental evisceration, visible penetration, retained knife, positive ultrasound or air in the peritoneal cavity on a plain X-ray) should be surgically explored. 

Emergency laparotomy is always performed under general anesthesia using a large midline incision. The first priority is to control major bleeding using compression by hands, four quadrant packing and other temporary hemostatic measures. After bleeding has been controlled, additional contamination from bowel lesions should be limited with temporary suturing, tying or stapling. The abdominal cavity is then cleaned and irrigated, and all organ injuries assessed in a careful and systematic manner exposing and mobilizing the organs to gain adequate access even to the retroperitoneal part of organs. After the organ injuries have repaired, the abdominal cavity is irrigated, drains are placed if necessary, and the wound closed without tension. Rarely, a destructive colon injury may require a colostomy. A badly contaminated skin wound should be left open. In major liver injuries, hemostasis may require perihepatic packing and temporary abdominal closure, resuscitation in the intensive care unit and planned reoperation after 12-48 hours to remove packs. This so called damage control (or abbreviated laparotomy and planned reoperation) approach can be extended to other massive, combined and complex injuries associated with severe physiological disturbances (acidosis, hypothermia and thretening coagulopathy). In the presence of massive visceral edema, even without the placement of packs, preventing wound closure without tension, the wound should be closed temporarily with a plastic bag (Bogota bag) or equivalent to prevent the development of Abdominal Compartment Syndrome.

Complications and prognosis

The most common surgical postoperative complications following laparotomy for penetrating abdominal trauma include wound infection, hemorrhage, anastomotic leakage, intra-abdominal abscess, prolonged bowel paralysis or obstuction, postoperative pancreatitis and Abdominal Compartment Syndrome. Major injuries, extensive blood loss and transfusions, prolonged preoperative hypotension, and long operative time may be followed by multiple organ dysfunction syndrome or failure (MOF) requiring prolonged treatment in an Intensive Care Unit. Missed injuries are feared complications associated with significant mortality. 

Incisional hernia and adhesive bowel obstruction are the most common late complications after trauma laparotomy. Occasionally, a missed diaphragmatic rupture or isolated pancreatic injury may manifest later as a diaphragmatic hernia or pancreatic fistula, respectively. 

The prognosis of patients with abdominal trauma is usually good. The hospital mortality rates for abdominal stab wounds is 1-5%, and for abdominal gunshot wounds 10-13%. The most common caused of death include uncontrolled hemorrhage from vascular or liver injuries, sepsis and multiple organ failure, and associated thoracic injuries. Cardiac complications and pulmonary embolism account for the majority of remaining fatalities.
 

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