Abdominal Trauma

Identifying serious intra-abdominal pathology can be a challenge. The mode of injury may cause other injuries that can distract attention from more serious problems that are undiagnosed at presentation.
There are 2 types of abdominal trauma; blunt and penetrating.

• Blunt trauma can result from either compression (secondary to a direct blow or against a fixed external object e.g. seatbelt), or from deceleration forces. The liver and spleen are the most frequently damaged organs. CT scanning has increased the identification of injuries.
• Penetrating trauma implies that either a gunshot wound ( or other high velocity missile/fragment), shrapnel or a stab wound has entered the abdominal cavity.
  • A gunshot wound is caused by a missile propelled by combustion of powder. It is associated with high-energy transfer and the extent of intra-abdominal injuries is inpredictable. Both the path of the missile is unpredictable and secondary missiles e.g. bone fragments or fragments of the bullet can inflict other injuries. The velocity of military firearms and hunting rifles is much higher than that of civilian handguns and therefore has a much higher energy transfer. Shotgun injuries, especially at close range, are frequently associated with massive tissue damage and should be regarded as high-energy transfer injuries.
  • Stab wound injuries can be inflicted by many objects other than knives, including knitting needles, garden forks, wire, fence railing, pipes and pencils. They are usually more predictable with regard to injured organs. However, a high index of suspicion must be maintained to avoid missing occult injuries.

The World Health Organisation states that falls from a height of less than 5 metres is the leading cause of accident morbidity worldwide. Road traffic accidents are the next leading cause.¹The National Paediatric Trauma Registry reported that 9% of paediatric patients with blunt abdominal trauma died. Of these, only 22% were reported as having intra-abdominal injuries as the likely cause of death. The male-to-female ratio is 60:40, according to national and international data. Most studies indicate peak incidence occurs in persons aged 14-30 years.

History

Initially, evaluation and resuscitation occur simultaneously.
In general, do not obtain a detailed history until life-threatening injuries have been identified and therapy has been initiated. However, to better predict injury patterns and to identify potential pitfalls, ascertain the mechanism of injury from bystanders, paramedics, or police.
AMPLE is often useful as a mnemonic for remembering key elements of the history:

• Allergies
• Medications
• Past medical history
• Last meal or other intake
• Events leading to presentation

A history of out-of-hospital hypotension is a predictor of more significant intra-abdominal injuries. Even if normotensive upon casualty department arrival, consider the patient as having an increased risk.

Examination

• Initial examination. After appropriate primary survey and initiation of resuscitation, focus attention on secondary survey of the abdomen.
• For life-threatening injuries requiring emergency surgery, comprehensive secondary survey should be delayed until the patient has been stabilised.
• Victims of blunt trauma who have a benign abdomen upon initial presentation, should have frequent serial examinations, in conjunction with the appropriate diagnostic studies, such as abdominal CT scan and bedside ultrasonography. This will ensure that occult injuries are picked up quickly.

• Examine the abdomen to determine the presence of external signs of injury. Note patterns of abrasion and/or bruising.
• Note injury patterns that predict the potential for intra-abdominal trauma e.g. lap belt abrasions, steering wheel-shaped contusions. In most studies, lap belt marks have been correlated with rupture of the small intestine and an increased incidence of other intra-abdominal injuries.²
• Observe the respiratory pattern, since abdominal breathing may indicate spinal cord injury. Note abdominal distention and any discolouration.
• Bradycardia may indicate the presence of free intraperitoneal blood in a patient with blunt abdominal injuries.
• The Cullen sign i.e. periumbilical ecchymosis may indicate retroperitoneal haemorrhage. However, this symptom usually takes several hours to develop. Flank bruising and swelling may raise suspicion for a retroperitoneal injury.
• Inspect genitals and perineum for soft tissue injuries, bleeding, and haematoma.

• Abdominal bruit may indicate underlying vascular disease or traumatic arteriovenous fistula.
• During auscultation, gently palpate the abdomen while noting the patient's reactions.

• Percussion tenderness constitutes a peritoneal sign.
• Tenderness indicates further evaluation and probably surgical referral is required.

• Carefully palpate the entire abdomen while assessing the patient's response. Note abnormal masses, tenderness, and deformities.
• Fullness and doughy consistency may indicate intra-abdominal haemorrhage. Crepitation or instability of the lower thoracic cage indicates the potential for splenic or hepatic injuries associated with lower rib injuries.
• Pelvic instability indicates the potential for lower urinary tract injury as well as pelvic and retroperitoneal haematoma. Open pelvic fractures are associated with mortality exceeding 50%.
• Perform rectal and bimanual vaginal pelvic examinations to identify potential bleeding and injury.
• Perform sensory examination of the chest and abdomen to evaluate the potential for spinal cord injury. Spinal cord injury may interfere with the accurate assessment of the abdomen by causing decreased or absent pain perception.
• Abdominal distention may result from gastric dilation secondary to assisted ventilation or swallowing of air.
• Signs of peritonitis e.g. involuntary guarding or rigidity soon after an injury, suggest leakage of intestinal content. Peritonitis due to intra-abdominal haemorrhage may take several hours to develop.

• Full blood count; normal haemoglobin and haematocrit results do not rule out significant haemorrhage. Do not withhold transfusion in patients who have relatively normal haematocrit results, but have evidence of clinical shock, serious injuries e.g. open-book pelvic fracture, or significant ongoing blood loss. Use platelet transfusions to treat patients with thrombocytopaenia and ongoing haemorrhage.
• Serum chemistry; most trauma victims are younger than 40 years old and are rarely taking medications that may alter electrolytes. If blood gasses are not routinely obtained, serum glucose and carbon dioxide levels are indicated.
• Rapid bedside blood-glucose determination; this can be obtained with a finger-stick measuring device and is particularly important for patients with altered mental status.
• Liver function studies; LFTs may be useful in the patient with blunt abdominal trauma. However, test findings may be elevated for coincidental reasons e.g. alcohol abuse.
• Urinalysis; indications for diagnostic urinalysis include significant trauma to the abdomen and/or flank, gross haematuria, microscopic haematuria associated with hypotension and significant deceleration mechanism of injury.
• Serum or urine pregnancy test; obtain this for all females of childbearing age.
• Coagulation profile; obtain PT/aPTT in patients who have a history of blood disorders or those who have synthetic problems e.g. cirrhosis, or for patients who take anticoagulants.
• Blood type, screen, and crossmatch; screen and type blood from all trauma patients with suspected blunt abdominal injury. If an injury is identified, this greatly reduces the time required for crossmatch. Perform an initial crossmatch of 4-6 units for those patients with clear evidence of abdominal injury and haemodynamic instability. Until crossmatched blood is available use O-negative or type-specific blood.
• Arterial blood gas (ABG); ABG may provide important information in major trauma victims. Upon initial investigation suspect metabolic acidaemia to result from the lactic acidosis that accompanies shock. A moderate base deficit indicates the need for aggressive resuscitation and determination of the aetiology. ABGs report total haemoglobin more rapidly than full blood counts do.
• Drug and alcohol screens; these should be performed on trauma patients who have alterations in their level of consciousness.
• Focused abdominal ultrasound for trauma(FAST). This can be performed at the bedside. FAST's diagnostic accuracy is generally equal to that of diagnostic peritoneal lavage (DPL)- see below. Free fluid in a haemodynamically unstable patient indicates the need for emergency laparotomy.^{3 4}
• CT scan; although expensive and potentially time-consuming, CT scan often provides the most detailed images of traumatic pathology and may assist in determination of operative intervention.⁵ The primary advantage of CT scanning is its high specificity and use for guiding non-operative management of solid organ injuries. CT scanning may miss injuries to the diaphragm and perforations of the GI tract, especially when CT scanning is performed soon after the injury. Pancreatic injuries may not be identified on initial CT scans but generally are found on follow-up examinations performed on high-risk patients. Transport only haemodynamically stable patients to the CT scanner. When performing CT scan monitor vital signs closely for evidence of decompensation.
• Diagnostic peritoneal lavage; This is used as a method of rapidly determining the presence of intraperitoneal blood. DPL is particularly useful if the history and abdominal examination of a patient, who is unstable and has multisystem injuries, is either unreliable or equivocal. DPL is also useful for those patients who cannot have serial abdominal examinations. Abdominal exploration always is indicated if approximately 10 mL of blood is aspirated upon insertion of the peritoneal catheter in the unstable patient.
• 85% penetrating chest injuries do not require thoracotomy. The patient can be treated with simple measures such as airway control. Theses injuries must take high priority and should be dealt with after securing the airway, obtaining intravenous access, and beginning fluid resuscitation.
• If the patient is haemodynamically stable, a CXR should confirm the presence of a pneumothorax. A loss of 20% of lung dimension on the CXR corresponds to 50% loss of lung volume. Do not observe a small pneumothorax as delayed increase may occur and become life threatening. Draining a major haemothorax or pneumothorax is essential in a patient with chest trauma. This establises adequate ventilation. Treatment should not be delayed by waiting for a CXR.
• Haemothorax and tension pneumothorax require a large-bore chest tube. This should be placed in the midaxial line, in the fifth or sixth intercostal space. A 20ml syringe with 1% lignocaine can be used not only to provide local anaesthesia, but also to help locate the upper edge of the rib in patients who are obese.
• CXR should follow chest tube placement immediately. If the pleural space still contains blood, insert another chest tube.
• Rigid sigmoidoscopy is indicated in all patients presenting with injuries in the pelvis or if blood is found on rectal examination.

• Perform a rapid primary survey to identify immediate life-threatening problems.
• Focus close attention on whether the patient can maintain the airway or if a potential threat is present. Secure airway by orotracheal intubation, which is performed with concurrent in-line manual immobilisation of the cervical spine. If intubation is required, and if possible, perform and record a brief neurological examination prior to neuromuscular blockade and intubation.
• Patients who display apnoea or hypoventilation require respiratory support, as do those patients with tachypnoea. Provide all patients with supplemental oxygen from a device capable of delivering a high FIO2 (eg, non-rebreather mask). Decreased or absent breath sounds raise the possibility of haemothorax or pneumothorax; therefore, consider needle decompression or tube thoracostomy, even prior to obtaining a chest radiograph.
• Identification of hypovolaemia and signs of shock necessitate vigorous resuscitation and attempts to identify the source of blood loss. Initiate at least 2 large-bore e.g.18-guage peripheral IV lines. Use central lines, preferably femoral using a large-bore line, and cutdowns e.g. saphenous, brachial for patients in whom percutaneous peripheral access cannot be established. Administer a rapid bolus of crystalloid.
• Perform physical examination that consists of a complete head-to-toe secondary survey, with attention paid to evidence of the mechanism of injury and potentially injured areas.
• Before the placement of a nasogastric tube and Foley catheter, perform appropriate head, neck, pelvic, perineum, and rectal examinations.
• Based on mechanism and physical examination, order initial trauma radiographic studies; trauma suite views include a lateral cervical spine, anterior portable chest, and pelvis radiograph. In-line spinal immobilisation must be continued until spinal fractures have been ruled out. Additional radiographs are indicated for other findings in the secondary survey.
• After the primary survey and initial resuscitation have begun, complete the secondary survey to identify all potential and present injuries.
• "Log-roll" the patient to examine the back and palpate the entire spinal column. Investigate for any signs of injury. Perform a rectal examination.
• If signs of shock persist after an initial 2-3 litres of crystalloid infusion, administer blood products. Type O Rh-negative blood typically is given to women of childbearing age. Type O-positive blood may be given safely to all other patients including men and postmenopausal women. As soon as available use type-specific or crossmatched blood.
• Bedside ultrasonography using a trauma examination protocol e.g. FAST can be used to determine the presence of intraperitoneal haemorrhage.
• If findings are negative or equivocal, a DPL may be performed in haemodynamically unstable patients.
• Based on stability, mechanism, and suspicion of intra-abdominal injury, further investigation may be warranted for patients who are haemodynamically stable after the initial assessment and resuscitation and who have negative or equivocal bedside ultrasound and/or DPL results.
• Further investigation includes contrast-enhanced CT scans of the abdomen and pelvis or serial examinations and ultrasound.
• Operative details of management can be found elsewhere.⁷

• Patients should be given written information describing signs of undiagnosed injury; increased abdominal pain or distention, nausea and/or vomiting, weakness, lightheadedness, fainting, or new bleeding in urine or faeces should prompt immediate return for further examination. Ensure repeat examinations are available for all returning patients.
• Be careful when prescribing analgesia to patients who are discharged; nonsteroidal anti-inflammatory drugs (NSAIDs) have potential to cause haemorrhage and should probably be avoided. Minimise use of analgesia in patients admitted for observation.
• Patients who undergo laparotomy may require routine perioperative antibiotics.
• Patients organ injury repaired may require extra antibiotics.