Table of Contents
Epidemiology of Abdominal and Pelvic Injuries
World over, firearm mortality rates have varied across different regions owing to laws governing use of firearms, from 0.05 in Japan to 14.24 in USA. Liver and spleen happen to be the most commonly injured organs by blunt forces followed by the small and large intestines. In penetrating injuries, however, one in two patients have their small bowels injured followed by colon, liver and vascular structures.
Mechanism of Injury
It is helpful to know the anatomical regions of the abdomen and its contents for a better understanding of the mechanisms underlying the abdominal and pelvic injuries.
There are three distinct compartments namely:
- Peritoneal cavity: Subdivided into the intrathoracic and abdominal segment. The intrathoracic segment is covered by bony thorax, which includes diaphragm, liver, spleen, stomach, and transverse colon.
- Retroperitoneum: This is a particularly difficult compartment because of its remote location rendering it less yielding towards a physical examination and peritoneal lavage. This region houses the aorta, vena cava, pancreas, kidney, ureters, and portions of duodenum and colon.
- Pelvic compartment: because of its anatomical location, injuries to rectum, bladder, iliac vessels, and internal genitalia of women are difficult to diagnose.
Abdomen and pelvic trauma can occur due to blunt, penetrating and explosion forces. In polytraumatic cases, blunt trauma forms the major bulk while penetrating injuries are less common.
Three mechanisms explain the occurrence of blunt injuries:
- Deceleration: A differential movement between adjacent structures owing to a rapid deceleration lies at the core of this mechanism. Shear forces cause hollow, solid organs and vascular pedicles to tear along their lines and points of attachment. So in classic injuries of liver, tears along ligamentumteres are often encountered, as are mesentric tears along bowel loops injuring the splanchnic vessels as well.
- Crushing: the solid organs trapped between the anterior abdominal wall and posterior thoracic cage are susceptible to crushing injuries.
- External compression: The compression could be a result of a direct blow or from external compression against a rigid fixed structure. In accordance with Boyle’s law, hollow organs are specially vulnerable as the compressive forces result in sudden rise in intraabdominal pressure.
- Gunshot wounds: While a gunshot wound involves high energy transfer giving rise to an unpredictable pattern of injuries, additional damage is done by bullet and bone fragments. The severity of a shotgun varies according to the distance of the victim from the weapon.
- Stab wounds: stab wounds have a more predictable pattern of injury wherein penetration of the abdominal wall is caused by a sharp object.
In both types of penetrating injuries, the mode of injury determines the underlying mechanism. While homicide is the predominant mode of injury in adult population, children are more susceptible to accidental penetrating injuries at home.
Clinical History and Examination of Abdominal and Pelvic Injuries
A detailed history and careful examination remain the cornerstone of management of patients with abdominal trauma.
- Primary survey includes assessment and concurrent resuscitation by following the ABCDE protocol. After initial resuscitation, GCS is assessed.
- The patient is to be completely undressed for a complete head to toe examination including the back and perineum area that are often missed out but are sources of significant bleeding.
- Abdominal distension, tenderness, obliterated liver dullness, deformed pelvis with tenderness are all suggestive of an intra abdominal and/or pelvic injury.
- Investigations are performed to confirm clinical suspicion. Patients with altered mental status or pelvic and retroperitoneal organ injury make examination difficult and are potential candidates for investigations.
Investigation of Abdominal and Pelvic Injuries
Diagnostic tools in care of trauma patients have a specific role in:
- Confirmation of clinical suspicion
- Decision regarding nature of procedure to be performed
- Evaluating and monitoring patient receiving nonoperative treatment
Chest X-ray AP and lateral view
- It is most often used to rule out chest involvement. It provides information regarding free intraperitoneal gas, herniation of abdominal contents etc.
X-ray pelvis AP view
- To rule out pelvic bone fracture as source of bleeding
Diagnostic peritoneal lavage
- When encountered with blunt trauma, DPL is reserved for patients with spinal cord injury or multiple injuries with unexplained shock, specially if the mental status of the patient is altered. Intoxicated patients with suspicion of abdominal injuries or those who will undergo prolonged anaesthesia are other candidates.
- Viable alternative in institutes where CECT and FAST facilities are not available
- It is an invasive procedure wherein a soft catheter is introduced into the peritoneal cavity for aspiration of lavage fluid or content that is then evaluated.
- Accuracy: 92-98 %; considered to be more accuarate than CECT in early diagnosis of bowel and mesentric injuries.
- Operative intervention indicated when:
- Free flowing blood at least 10 ml in volume aspirated
- Presence of Nike and food particles
- Presence of RBC > 100,000/mm3, leukocyte count > 500/mm3, amylase level >175 U/dL
- Presence of bacteria
- Drawbacks: procedural difficulty in performing in patients with prior surgeries, prenatal women, obesity.
FAST (Focused assessment with sonography for trauma)
In patients with polytrauma who are hemodynamically unstable and refractory to fluid administration and blood transfusion, bedside FAST is the only imaging method beneficial in them. Free fluid in the abdomen and pelvis suggest intraabdominal hemorrhage.
- Sensitivity: 73-88 %
- Specificity: 98-100 %
- Grading of solid organ injury not possible
- May miss out injuries that are not associated with significant hemorrhage
- May cause injury to retroperitoneum
It is the investigation of choice for hemodynamically stable patients.
- Provides information regarding injury to retroperitoneal structures, diaphragm, and solid abdominal organs.
- Grading of injuries can be obtained.
- Presence of free fluid in the abdomen in the absence of solid organ injury is suggestive of bowel, mesentric or urinary tract injuries.
- Accuracy: 92-95 %
- Highly sensitive and specific for hepatic and splenic injuries
Specific Types of Injuries
- A detailed history regarding the anatomical location of the injury gives a clue to splenic damage.
- Left rib fractures must not be ignored as they are often associated with splenic rupture.
- Severe chest or neurological damage make assessment of minor splenic trauma difficult.
- History of malaria, lymphoma, hemolytic anaemia is important as even minor trauma can cause disproportionate damage in an enlarged spleen.
- While all basic lab tests may be performed, complete blood cell count is most useful in pointing towards deteriorating hemodynamic stability.
- The most specific and sensitive study for splenic injury is CT scan (triple helical scan). It is up to 98 % sensitive for splenic injuries when IV contrast is given. While it can detect small quantities of blood in abdominal cavity, it is contraindicated in hemodynamically unstable patients.
- Other investigations include FAST, diagnostic peritoneal lavage, angiography but have a limited role to play.
- Immediate splenectomy indicated in:
- Patients with severe multiple injuries
- Splenic avulsion
- Fragmentation or rupture
- Extensive hilar injuries
- Failure of hemostasis
- Peritoneal contamination from gastrointestinal tract
All patients are to be administered polyvalent pneumococcal vaccine post splenectomy.
- Conservative approach
- In patients with no other associated abdominal injuries, conservative approach may be used given their hemodynamic stability and age not more than 55 years.
- Patients are kept under an observation period for 10-14 days; delayed rupture and hemorrhage may occur, usually in first 48 hours. This is followed by bed rest for a week.
- They are advised to not indulge in any strenuous activity for a period of 6-8 weeks and engage in sports activities for a period of 6 months at least.
It is quite a common injury that is encountered in the emergency department, yet also the most frequently missed injuries in trauma deaths. A per abdominal examination may provide vague clues to an injury but these are often missed. For this reason, diagnosis is usually made at laparotomy or CT scan.
Basic lab tests:
- Complete blood cell count (CBC)
- Coagulation profile: Along with CBC, these two basic lab tests are done to obtain baseline levels of PT, APTT and platelet count as dilutionalcoagulopathy and thrombocytopenia are common after hepatic repair.
- Clotting factors
- Liver and kidney function tests
- Chest X-ray to rule out chest involvement
- CT scan is considered to be the most specific and sensitive test for liver injury.
- Diagnostic laparoscopy: since associated injury to the diaphragm is common with hepatic injury, diagnostic laparoscopy makes for a good test for ruling out such associated injuries.
- Angiography is less valuable as a diagnostic tool but transcatheter embolisation has found use in management of persistent hepatic bleeding that is not stopped by surgery.
- Packing and limited surgery is a viable option when coagulopathy and hypothermia develop.
- Conservative management is more often used for hemodynamically stable patients with no other associated abdominal injuries and peritoneal signs.
Caused by high energy blunt trauma following a fall, road traffic accident or crush injury, pelvic injuries account for 13-23 % mortality in these cases.
- The patient presents with a typical history of pain on movement and gross hematuria.
- A quick observation reveals structural instability with peripelvic ecchymoses.
- A digital rectal examination is important to identify injury to the rectum and locate the prostate.
- Hemoperitoneum may lead to hypotension.
Basic lab tests:
- Complete blood cell count has an important role in management of pelvic bleeding.
- Liver and kidney function tests
- Coagulation profile
- X-ray to rule out associated pelvic bony fractures and injury and associated abdominal injuries
- Diagnostic peritoneal lavage performed at the earliest in hemodynamically unstable patients as it is a good modality to identify hemoperitoneum.
- Laparotomy: if gross bleeding is seen, this should be followed by external fixation and angiography.
The main aim of management of pelvic injury is assessment and control of bleeding.
- Hemodynamically unstable patient: early open DPL performed
- Gross bleeding on laparotomy: External fixation helps to minimise bleeding from veins and small arterioles near fracture sites. It also adds to the tamponade effect by shrinking the volume of an open pelvic cavity. This is followed by angiography with embolisation, which is often effective in controlling arterial bleeding but is difficult to perform.
- Large vessel bleeding: surgical control
- If bleeding is hinted only by low blood cell counts, risk of major intraabdominal hemorrhage is low.
- A detailed history regarding the anatomical location of the wound and the type of weapon used is important. Number of gunshots heard or number of times the patient was stabbed, the position of the victim and the environment under which the incident took place help assess the severity and extent of damage.
- Additional information regarding allergies, medications currently being taken by the patient, history of any prior illness or surgery and last meal had by the victim help in providing the best management possible.
Signs and symptoms
- Primary survey: initial examination for assessment of ABCDE:
- Airway, breathing and circulation (ABC)
- Level of consciousness (D – disability), neurological deficits to be looked for
- Location of wound (E – exposure), inspection of all body surfaces
- Amount of blood loss
- Type of weapon or object used
- Secondary survey: includes complete head to toe examination (in hemodynamically stable patients).
- A rapid per abdomen examination for tympany, dullness to percussion, bowel sounds or distension coupled with a digital rectal and genitourinary examination is done.
- In life threatening cases, secondary survey may be reserved for after the operative therapy.
- Indications for immediate surgical exploration:
- Narrow pulse pressure
- High or low respiratory rate
- Peritoneal signs (pain, guarding, rebound tenderness)
- Diffuse or poorly localised pain that fails to resolve
- Basic lab tests for patients undergoing immediate surgery:
- Blood type and cross match
- Complete blood cell count
- Liver and kidney function tests, specially blood urea nitrogen and serum creatinine
- Blood glucose
- Coagulation profile
- Arterial blood gas
- Electrolyte levels along with calcium, phosphate and magnesium levels
- Toxicology screen
- Imaging studies:
- Chest X-ray: Initial investigation to rule out involvement of chest cavity
- Abdominal radiography: both anteroposterior and lateral views taken
- Chest and abdominal ultrasonography: focused assessment with sonography (FAST) for trauma with four views (pericardial, right and left upper quadrants, pelvis)
- CT scan abdomen: most sensitive and specific study in cases of liver or spleen injury
Management of Abdominal and Pelvic Injuries
A multi pronged approach is used to manage the patient, which can be described under the following headings:
These include procedures that are used for monitoring the status of the patient and also entail therapeutic uses at the same time.
- Gastric decompression in intubated patients
- Foley catheterisation
- Peritoneal lavage
- Tube thoracotomy
- Local wound exploration to determine track of layers penetrated
- Gunshot wounds are almost always associated with intraabdominal injuries that mandate laparotomy.
- Stab wounds, in contrast, have a lower incidence of intraabdominal injuries and hemodynamically stable patients may be provided expectant treatment.
It is very much palliative in nature with obvious choices:
- Analgesics: morphine, fentanyl
- Anxiolytics: lorazepam, midazolam
- Antibiotics: metronidazole, gentamicin, vancomycin
- Neuromuscular blocking agents: succinylcholine
- Immune enhancement: tetanus toxoid