Chapter 5 – Abdominal Trauma




Abstract




Traffic collisions, followed by falls, are by far the most common cause of severe blunt abdominal trauma. Solid organs, usually the spleen and liver, are the most commonly injured organs. Hollow viscus perforations are fairly uncommon (about 3% of blunt abdominal trauma), and they are often associated with seat-belts or high-speed deceleration injuries.





Chapter 5 Abdominal Trauma


Demetrios Demetriades and Kenji Inaba



Blunt Abdominal Trauma



Introduction


Traffic collisions, followed by falls, are by far the most common cause of severe blunt abdominal trauma. Solid organs, usually the spleen and liver, are the most commonly injured organs. Hollow viscus perforations are fairly uncommon (about 3% of blunt abdominal trauma), and they are often associated with seat-belts or high-speed deceleration injuries.


There are five main mechanisms of injury with blunt trauma:




  1. 1. Direct crushing of organs between the anterior and posterior abdominal walls



  2. 2. Avulsion injuries from deceleration forces, as in high-speed collisions or falls from a height



  3. 3. Transient formation of a closed bowel loop with high intraluminal pressure and rupture of the hollow viscus.



  4. 4. Lacerations by bony fragments (e.g., pelvis, lower ribs).



  5. 5. Sudden and massive elevation of the intra-abdominal pressure (usually seat-belted individuals involved in high-speed collisions) may cause diaphragmatic or even cardiac rupture.



Clinical Examination


The clinical evaluation of blunt abdominal trauma is often complicated by associated abdominal wall trauma, fractures of the lower ribs or pelvis, head injuries with depressed level of consciousness, and spinal injuries. These conditions may make clinical examination difficult and unreliable, and significant hollow viscus injuries may be missed with potentially serious consequences.


Rigidity and severe or increasing abdominal tenderness are suggestive of developing peritonitis. These findings, however, may be less reliable in patients with abdominal wall bruising, or fractures of the lower ribs or pelvis. Pain referred to the left shoulder (Kehr’s sign) is suggestive of splenic injury. Similarly, pain referred to the right shoulder is suggestive of hepatic injury. Often, these signs can be elicited by placing the patient in the Trendelenburg position. A “seat-belt sign” on the abdominal wall is associated with a high incidence (about 20%) of significant intra-abdominal injuries.



Investigations




  1. 1. FAST: FAST is the most valuable emergency department investigation in the evaluation of abdominal trauma. The FAST uses ultrasound to identify the presence or absence of free intraperitoneal fluid by evaluating the hepatorenal, splenorenal, and suprapubic spaces (see Chapter 25, Ultrasound in Trauma). It is quick, noninvasive, safe, portable, and fairly accurate. The FAST exam is unable to evaluate the retroperitoneum, is operator dependent, and, if positive, does not identify the source of fluid. FAST is most useful when positive. Small volume hemoperitoneum or clotted blood can result in a false negative FAST. The presence of free fluid on ultrasound in a hemodynamically unstable patient is an indication for urgent laparotomy. However, in hemodynamically stable patients, an abdominal CT scan may be the most appropriate next step.



  2. 2. Plain X-rays: A chest X-ray is part of the abdominal evaluation. Routine pelvis X-ray in an alert asymptomatic patient is not indicated if a CT scan is planned. However, a pelvic X-ray is indicated in unstable patients with a suspected fracture, in order to evaluate the type of fracture and to determine the potential need and safety of a pelvic binder.



  3. 3. CT scan: Contrast CT scan has become the most important and useful investigation in the evaluation of suspected blunt abdominal trauma. It is very sensitive in diagnosing solid organ injuries. In addition to the site and size of solid organ injury, it may give valuable information about the presence of active bleeding or false aneurysms. The role of CT scan in the diagnosis of hollow viscus perforation is rather limited, and up to 30–40% of injuries may be missed, especially if the CT scan is performed very soon after the injury. CT scan findings suggestive of bowel injury include pneumoperitoneum, thickened bowel wall, extravasation of oral contrast, fat stranding, and free intraperitoneal fluid in the absence of solid organ injury.



  4. 4. Diagnostic peritoneal lavage (DPL): DPL has largely been replaced by the FAST exam. Diagnostic peritoneal aspirate (DPA), however, has an important role in the evaluation of the abdomen in a hemodynamically unstable patient, if the ultrasound is not definitive or available. The procedure can be performed with the open or percutaneous closed technique (see Chapter 22, Diagnostic Peritoneal Aspirate). The aspiration of gross blood during a DPA is an indication for laparotomy in the hemodynamically unstable patient.



  5. 5. Intravenous pyelogram (IVP): One-shot IVP in the emergency department has little or no role in the evaluation of abdominal trauma. Formal IVP has largely been replaced by contrast CT scan, though it may still have a role in suspected ureteric injuries.



  6. 6. Catheter angiography: This is an important therapeutic tool in selected cases of abdominal trauma, where CT scan findings are suggestive of bleeding from pelvic fractures or solid organ injuries, false aneurysms, or arteriovenous fistulas.



  7. 7. Magnetic resonance cholangiopancreatography (MRCP): This is a good investigation for the evaluation of the integrity of the pancreatic duct in pancreatic trauma.



  8. 8. Urinalysis: All patients should be evaluated for hematuria. Gross hematuria should be evaluated by means of contrast CT scan and cystogram. Asymptomatic microscopic hematuria does not need further evaluation.



  9. 9. Serum amylase and lipase: These levels may be useful laboratory tests for suspected pancreaticoduodenal trauma, although the sensitivity and specificity are fairly low. Normal levels do not reliably exclude pancreatic trauma, and they are elevated in only about 70% of cases with proven pancreatic trauma. Serum amylase will rise more rapidly after pancreatic trauma; however, it is less specific. Serum lipase levels may be in normal range soon after pancreatic trauma and may not show significant elevation until the following day. Serial measurements are more useful than the initial values.



General Management


The initial evaluation and management should follow standard ATLS protocols. A FAST exam is part of the standard evaluation of all patients with abdominal trauma. Hemodynamically unstable patients with a positive FAST should be taken to the operating room without delay. CT scan evaluation should be reserved only for the patient who is hemodynamically stable and whose diagnosis is uncertain.


In the multi-trauma patient, there is often combined abdominal and head trauma. The timing of evaluation and management of the injuries of these two anatomic areas is important and can have major effects on outcome. In the presence of hemodynamic instability, the abdomen should be evaluated by FAST, and in the setting of an equivocal FAST, a DPA is performed. If there is evidence of free intraperitoneal fluid, the patient should undergo laparotomy with a post-operative head CT scan. If there are localizing neurological signs, burr holes may be considered during laparotomy before CT evaluation. This approach should be considered very rarely because the burr holes are often placed on the wrong site and it is a time-consuming procedure. In the hemodynamically stable patient with peritonitis and abnormal GCS, a CT scan of the head should precede laparotomy, under close monitoring. It is rare that both a laparotomy and a craniotomy are required simultaneously. Bleeding control in the abdomen is always the first priority.


Many carefully selected patients with solid organ injury (liver, spleen, kidney) can safely be managed nonoperatively, provided they are hemodynamically stable and have no signs of peritonitis. Overall, approximately 70% of blunt liver injuries, approximately 80% of splenic injuries, and 90% of renal injuries can be managed nonoperatively. Angioembolization should be considered in patients with CT scan evidence of active bleeding or false aneurysms.



Tips and Pitfalls




  • Delayed diagnosis of hollow viscus perforation in a clinically unevaluable patient (e.g., associated head injury, spinal cord injury, or intoxication) is a serious complication. The presence of a seat-belt sign should raise the index of suspicion for abdominal trauma. Certain CT scan findings, such as bowel edema, intraperitoneal gas, and free intraperitoneal fluid in the absence of a solid organ injury, are suspicious of hollow viscus perforation. Serial WBC and follow-up abdominal CT scan should be considered in suspicious cases.



  • Pancreaticoduodenal injuries are notorious for their fairly silent clinical presentation. The initial CT scan may miss the injury, and the serum amylase or lipase may be normal. Close clinical monitoring, repeat CT scan, and serial enzyme determinations should be performed.



  • The FAST exam is not always reliable, and no major decisions should be made exclusively based on the findings of the FAST exam. The hemodynamic condition of the patient should be taken into account when deciding management.



Mechanism of Injury


Intra-abdominal injuries may occur by crushing of an organ against the spine, pelvis, or ribs and the abdominal wall; after deceleration, such as high-speed collisions or falls from a height by sudden increase of the intraluminal pressure and bursting of a hollow viscus, commonly seen with seat-belt injuries (Figure 5.1 AC, Figure 5.2 AC, Figure 5.3).





Figure 5.1 A–C Direct crushing injury to spleen following an auto versus pedestrian collision (A). Crushing injury to the liver following a motor vehicle collision (B). Crushing injury to the kidney following a fall from a height (C).





Figure 5.2 A–C Mesenteric “bucket handle” avulsion injury to small bowel from deceleration injury following a high-speed motor vehicle collision (A). Mesenteric “bucket handle” avulsion injury and necrosis of the small bowel, from deceleration injury following a high-speed motor vehicle collision (B). Deceleration injury with avulsion of the right colon and distal ileum, following a high-speed motor vehicle collision (C).





Figure 5.3 Small bowel rupture due to closed loop and increased intraluminal pressure. The rupture occurs at the antimesenteric border.


Seat-belts have significantly decreased mortality rates after motor vehicle collisions. Although the incidence of intra-abdominal injuries has not changed with the use of seat-belts, the nature of the injuries has changed: seat-belt wearers are more likely to suffer hollow viscus perforation.


The presence of seat-belt marks on the abdominal wall is an important physical finding because of the high incidence of associated intra-abdominal injuries. In patients wearing a seat-belt, approximately 20% with a seat-belt sign will have intra-abdominal injury versus only approximately 3% without a seat-belt sign (Figure 5.4 A,B).





Figure 5.4 A,B Abdominal seat-belt mark in a motor vehicle collision victim. The presence of this sign is a marker associated with a high incidence of intraabdominal injury (A). Intraoperative photograph of the same patient showing perforation of the small bowel (B).



Diagnosis of Hemoperitoneum


Hemoperitoneum by itself usually does not result in peritoneal signs. Thus the clinical diagnosis, especially in the presence of multi-trauma, can be difficult. FAST exam, performed in the emergency department is a fast, usually reliable, and noninvasive method of detecting intraperitoneal bleeding. DPA has a role in the evaluation of an unstable patient when the FAST exam is not diagnostic or not available. CT scan evaluation should be considered in hemodynamically stable patients. Under these circumstances, CT scan is the most valuable investigation (Figure 5.5).





Figure 5.5 Positive diagnostic aspirate (DPA).



Splenic Injuries


The clinical presentation of splenic rupture may vary from mild left upper quadrant pain to severe hypovolemic shock. The diagnosis may be suspected from the clinical examination (pain in left upper abdomen often radiating to the left shoulder, signs of hypovolemia) or FAST exam showing free intraperitoneal fluid and confirmed by CT scan (Figure 5.6 A, B, Figure 5.7, Figure 5.8 A, B, Figure 5.9 A, B ).





Figure 5.6 A,B Abdominal CT scan with a grade IV spleen injury (A). Surgical specimen of the removed ruptured spleen (B).





Figure 5.7 Grades of splenic injuries, according to the American Association for the Surgery of Trauma classification. Most grade I–III injuries can safely be managed nonoperatively. The majority of grade IV or V injuries require operative management.





Figure 5.8 A,B CT scan showing a large intrasplenic aneurysm (A). Angiography showing multiple intrasplenic pseudoaneurysms (B). These injuries can be managed with angioembolization.





Figure 5.9 A,B CT scan showing a splenic aneurysm, following blunt trauma (A). Angiography confirms an intrasplenic pseudoaneurysm, which was successfully embolized (B).


Most isolated minor or moderate severity (grades I–III) splenic injuries can safely be managed nonoperatively (about 90% in children, 70% in adults), while severe injuries (grades IV or V) more often fail nonoperative management. The criteria for a trial of nonoperative management are hemodynamic stability, no signs of peritonitis, and no other indications for laparotomy. The abdominal CT scan is the standard method used to grade splenic injury, and high-grade injuries or those with high-risk features (hilar injury, false aneurysm, active contrast extravasation) may benefit from angioembolization or operative intervention. A dual-phase CT protocol can be useful to distinguish active extravasation of contrast from false aneurysm. Caution should be exercised in the selection of patients for nonoperative management in the presence of multiple associated severe injuries. Severe splenic injuries treated nonoperatively should be followed up by serial CT scans until there is satisfactory healing or absorption of any large hematomas. Subcapsular hematomas may rupture and bleed dangerously many days or weeks after injury (Figure 5.10 ).





Figure 5.10 Operative specimen of a subcapsular splenic hematoma that ruptured many weeks after the injury.


Post-splenectomy complications may be systemic (post-splenectomy sepsis or thrombocytosis) or local (subdiaphragmatic abscess, pancreatic pseudocyst or fistula, gastroparesis, necrosis of the fundus of the stomach, thrombosis of the splenic vein, left pleural effusion, and atelectasis). To avoid post-splenectomy sepsis, vaccines targeting Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae should be administered to all patients. The vaccines are most effective if given before splenectomy. It is advisable that patients with high-grade injuries selected for nonoperative management receive the vaccine, in case the management fails and a splenectomy is needed. The splenectomized patient should be advised that medical care should be sought with the first signs or suspicion of any infections.



Liver Injuries


The clinical presentation of a liver injury may vary from minor pain in the right upper abdomen to hypovolemic shock. The diagnosis is suspected based on the physical examination and confirmed by CT scan or laparotomy. Most minor and moderate liver injuries (grades I–III), and even some severe injuries (grades IV and V) may be successfully managed nonoperatively, provided the patient is hemodynamically stable and there is no peritonitis. Hemodynamically stable patients with extravasation of contrast on CT scan, indicating bleeding or false aneurysm, are excellent candidates for angioembolization (Figure 5.11 AF, Figure 5.12 AC, Figure 5.13 AC, Figure 5.14 AC ).





Figure 5.11 A–F CT scans of various grades of blunt liver trauma: grade I (A), grade II (B), grade III (C), grade IV (D) with false aneurysm (circle), grade V injury, with extension toward the inferior vena cava (E), grade V injury with active bleeding (circle; F).





Figure 5.12 A–C CT scans of a small (A) and a large (B, C) subcapsular liver hematomas following blunt trauma.





Figure 5.13 A–C CT scan shows a large pseudoaneurysm of the hepatic artery (A). The finding is confirmed by angiography (B), and the lesion is successfully managed with angioembolization (C).





Figure 5.14 A–C Intraoperative appearance of severe liver injuries: grade III (A), grade IV (B), grade V (C). In the grade V injury, there is avulsion of the hepatic veins and tear of the inferior vena cava (circle).


Posttraumatic liver complications include liver abscess, biloma, biliary leak, liver necrosis, false aneurysm, and hemobilia (bleeding into the biliary tree). Most of these complications can be managed with percutaneous drainage, endoscopic retrograde cholangiopancreatography (ERCP) stenting, or angiographic embolization (Figure 5.15 A,B, Figure 5.16 A,B ).





Figure 5.15 A,B Large bilomas many weeks after blunt severe liver injury. The patients were successfully managed with percutaneous drainage.





Figure 5.16 A,B This patient presented with a copious amount of blood in the nasogastric tube soon after a grade IV liver injury. This finding is highly suspicious of hemobilia. Angiogram confirming pseudoaneurysm and hemobilia (A), which was successfully embolized (B).



Pancreatic Injuries


Most pancreatic injuries due to blunt trauma occur at the neck of the pancreas, caused by crushing of the organ against the spine. The clinical presentation may vary from mild epigastric pain to peritonitis. The diagnosis is suspected from the history of abdominal trauma and confirmed by specific investigations or at operation. The initial serum amylase or lipase may be elevated in about 70% of patients, and serial measurements should be performed in suspected cases. The CT scan is usually diagnostic, although the early CT scan may not show the injury. It is essential that in suspected cases a repeat CT scan be performed 6–8 hours after the initial investigation. ERCP or MRCP may be useful in determining any damage to the duct (Figure 5.17 A,B, Figure 5.18 ).





Figure 5.17 A,B CT demonstrating distal pancreatic transection (circle; A). 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; B).

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Apr 22, 2021 | Posted by in EMERGENCY MEDICINE | Comments Off on Chapter 5 – Abdominal Trauma
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