046- Abdominal Trauma

What are advantages of FAST U/S over CT? Disadvantages?

-less time consuming -can be done in the trauma bay without having to move patient -no radiation -can be done serially Disadvantages: -will not detect solid organ damage or bowel perforation if there is not significant associated bleeding -limited by body habits of patient, and requires cooperative patient -more operator dependent than CT -cannot distinguish blood vs. ascites vs. urine as a cause for the fluid -high false negative rate in the setting of pelvic #

Name 4 causes of intraperitoneal free air.

-perforated viscous -pneumomediastinum -pulmonary injury -barotrauma

How should a patient with an abdominal stab wound in whom there is evidence of peritoneal breach but they do not meet criteria for immediate laparotomy be managed?

According to the algorithm described in Rosen's, these patients should be managed with further imaging (CT, DPL, serial physical exams, laparoscopy) to identify if there is an actual INJURY associated with the breach of the peritoneum. If yes, then they should proceed to laparotomy. If not, then should be kept for 12-24h observation.

What are the advantages of FAST U/S over DPL? Disadvantages?

Advantages: -takes less time -can evaluate intra-thoracic structures as well -non-invasive -can be performed serially for ongoing assessment Disadvantages: -limited by body habits of patient, and requires cooperative patient -more operator dependent than DPL -less sensitive than DPL for detecting blood in the peritoneum -cannot distinguish blood vs. ascites vs. urine as a cause for the fluid -high false negative rate in the setting of pelvic #

Describe the anatomical borders of the anterior abdomen, lower chest, flank, and back.

Anterior abdomen = from anterior axillary line on either side to anterior costal margin superiorly and groin creases inferiorly Lower chest = From T4 anteriorly and T7 (scapular tip) posteriorly down to the inferior costal margins Flank = anterior to posterior axillary line, from T7 (scapular tip) to iliac crest Back = from inferior costal margin to iliac crest, and from posterior axillary line on either side

How does retroperitoneal free air appear on plain XR?

Apperas as "stippling" pattern (like soap bubbles), outlining the duodenum, kidney, or psoas muscle (all retroperitoneal structures).

What is the caviat about using hemoglobin or hematocrit as a measure of acute blood loss in the setting of trauma?

Both are measure of blood CONCENTRATION, therefore they may not decrease acutely, even in the setting of significant blood loss. Serial measurements can be more helpful.

In a patient with a suspected intra-abdominal perforation, in addition to hemorrhage control and resuscitation, what specific treatment should be initiated prior to laparotomy?

Broad spectrum (gram negative and coliforms) antibiotic x 1 dose (e.g. Pip Tazo)

What type of CT (non-contrast, PO contrast, IV contrast) is recommended for evaluation of abdominal trauma?

CT with IV contrast provides the most information CT with contrast is generally recommended, as it can better evaluate for hemorrhage and source of bleeding. However, PO contrast has not been found to add much additional information over IV contrast, plus it causes time delays and aspiration risk for the patient, therefore is no longer indicated for most cases.

What specific test can be done in the setting of suspected small bowel perforation?

Can consider UGI series with water-soluble contrast (e.g. gastrograffin)- always use water soluble in the setting of ?perforation

What are Grey-Turner and Cullens signs? What do they indicate? Why are they not helpful in the acute stage of illness?

Grey-Turner = ecchymotic discolouration at the flanks Cullens = ecchymotic discolouration around the umbilicus Indicative of retroperitoneal bleeding. May not appear until >12h after injury, so not acutely helpful.

Why are injuries secondary to high velocity missiles often underestimated clinically?

High velocity missiles tend to cause extensive cavitation injuries upon impact (transfer of energy into surrounding tissues, causing extensive but temporary cavitation), which then bounces back into position. Can look quite benign but harbour extensive injury.

How are liver/spleen injuries managed differently in paediatric patients in the setting of blunt abdominal trauma (compared to adults)?

In general, in adults and peds, move is towards more conservative management of even high grade liver/spleen injuries. However, there is especially good evidence in paediatrics that conservative management of liver/spleen trauma has better outcomes than OR management.

In what setting is DPL known to cause false positive results?

In the setting of pelvic fractures with retroperitoneal hematomas.

How does presence of suspected aortic injury affect management of blunt abdominal trauma?

In the unstable patient, hemoperitoneum and unstable abdomen should take priority over presumed aortic injury (i.e. laparotomy before chest diagnostics), as abdomen hemorrhage is more likely to kill more rapidly. If sudden deterioration occurs, can consider thoracotomy + aortic cross clamping. In the stable patient, can proceed with diagnostics for both chest and abdo.

What is significant about the time line of diagnosis for intra-abdominal blunt trauma injuries (e.g. seatbelt-related abdominal injuries after MVC)?

Injuries may present days to weeks after the initial trauma, particularly injuries to the small bowel (most commonly the jejunum).

What is suggested by elevated lipase in the setting of abdominal trauma?

Non-specific Does not necessarily correlate with pancreatic injury (normal lipase does not rule out pancreatic injury, and elevated lipase does not necessarily indicate a pancreatic injury). Not considered useful in the setting of abdominal trauma.

What is suggested by scapular tip or neck pain in the setting of abdo trauma? What is indicated by pain that radiates into the testicles?

scapular tip/neck --> think about hemoperitoneum irritating the diaphragm, often with liver/spleen injuries testicular pain --> think about retroperitoneal injury

What is the "ALARA" principle?

"As low as reasonably achievable" This is the principle of trying to minimize radiation to patients, while also minimizing missed injuries. This balance is often achieved both at an individual physician/patient level, as well as at an institutional level, and in conjunction with the department of radiology.

List the 7 clinical indications for laparotomy following penetrating abdominal trauma. List any associated pitfalls with each of the signs.

*the same criteria apply to both stab wounds and GSWs

Describe an algorithmic approach to anterior abdominal wound secondary to penetrating trauma, in terms of decision re: laparotomy vs. observation vs. discharge home (Rosen's figure).

*this algorithm is essentially the same for either stab or GSWs

How does the presence of a closed head injury affect the blunt abdominal trauma?

1) Airway must take priority over all else if this is compromised, establish definitive airway 2) Generally, unstable abdomen takes priority over head injury, UNLESS lateralizing signs or coma. In unstable patient with intraperitoneal hemorrhage + lateralizing neuro findings, decision must be made to prioritize one over the other (craniotomy vs. laparotomy vs. both simultaneously, involve surgeons in this decision). If unstable with EITHER intraperitoneal hemorrhage OR lateralizing findings, then prioritize the condition that is worse and proceed to lap vs. crani, respectively.

Describe the two different ways that a DPL can be considered positive.

1) DPL is positive if the initial aspirate from the intraperitoneum has frank blood or gastric contents 2) If the initial aspiration is negative, then intraperitoneal lavage is done; at least 250-300cc of fluid must be lavaged back in order for results to be reliable, but is considered positive if there are significant RBCs (cutoff level varies depending on location and type of trauma), significant WBCs, or frank blood/gastric contents

List 5 ways (either clinical exam or investigations) that can rule in peritoneal violation after penetrating abdominal trauma.

1) Evisceration- eviscerated bowel indicates clearly that the peritoneum has been violated 2) Intraperitoneal air- may be seen on XR, suggests that the peritoneum has been violated by the knife/tool of injury; can get false positive if air is actually coming from pulmonary tract 3) Local wound exploration- to directly identify breach of the peritoneum 4) Ultrasound- may identify hemoperitoneum, pneumoperitoneum, or pericardial effusion 5) Laparoscopy

Discuss 6 ways that peritoneal violation can be determined in the setting of an abdominal GSW, and discuss the pitfalls associated with each.

1) Missile trajectory- can estimate by looking at entrance and exit wounds to see if this is likely to have violated peritoneum, but can be unreliable if bullet ricochets 2) Plain radiographs- may identify a bullet left in the intraperitoneal region, but not helpful for through and through injuries, and often imprecise estimates of bullet location 3) Local wound exploration- can be more challenging and less obvious/reliable in GSWs than stab wounds, due to extensive tissue damage and mangling 4) U/S- may be able to identify wound tract, but utility for GSWs very limited 5) Laparoscopy- lower threshold to do this is GSWs, costly and invasive but may also lend itself to injury repair at the same time as diagnosis 6) CT- useful for identifying wound tract and associated injuries, as well as identifying vascular injuries

List 3 disadvantages of CT scanning in the setting of abdominal trauma:

1) relatively insensitive for picking up injuries of the pancreas, diaphragm, small bowel, and mesentery 2) adverse reactions to contrast 3) danger of physically having to move patient out of resus bay and into the CT scanner

What are the 2 goals of early diagnostic injuries in the setting of blunt abdominal trauma? What diagnostic tools/tests can be used to do this in the setting of an unstable patient? In a stable patient?

1) to identify intraperitoneal hemorrhage in the unstable patient (will change management) -FAST U/S or DPL are preferred tests -CT can be considered, but challenging to do in an unstable patient, requires MD accompaniment and resuscitation 2) to identify other organ injury that might require operative repair in a more stable patient -CT scan is preferred, can assess the retroperitoneum and is the best test for identifying liver/spleen injuries -U/S and DPL can also help to identify hemoperitoneum suggestive of other injury

What is the difference between a closed and open DPL?

Closed = done with needle aspiration +/- modified seldinger technique to thread a catheter through the peritoneum Open = layer by layer dissection down to and through the peritoneum, leaving open access to the intraperitoneal cavity, and into which a catheter is placed

Generally, what is the conservative vs. liberal approach to abdominal GSW with peritoneal violation?

Conservative approach (used by most centres) is that GSW + peritoneal violation is an automatic laparotomy, with no further investigations into the type of injury sustained by the GSW. Liberal approach at some centres is to do further investigations to try to identify injury secondary to the GSW (CT, DPL, serial exams), and if no injury is readily identify,d may proceed with observation rather than automatic laparotomy.

In an abdominal trauma patient with an equivocal CT but a strong clinical suspicion of intra-abdominal injury, what test could be done as a follow up?

Consider DPL

What is the only absolute contraindication to DPL? What are relative contraindications?

DPL is absolutely contraindicated if the need for laparotomy has already been established. Relative contraindications: -prior abdominal surgery/infection -coagulopathy -obesity -2nd or 3rd trimester pregnancy (may require a change in entry position of the DPL)

What is the function of a shotgun? Describe it's intended use, bullets, and classifications of injury patterns.

Designed to hit a fast-moving target at close range. Bullet speed slows down quickly (therefore not useful for shooting long distances). Shoots multiple tiny bullets at one time. At closer range to the target, bullets are more concentrated, and victim is more likely to be hit by many bullets in a concentrated region. At farther distances, bullets have splayed outwards, so victim is more likely to be hit by only 1 or 2 pellets spread apart. Shot gun wounds are categorized by distance: Type 1 wound = long distance (>6m), usually involves subq tissue and deep fascia only Type 2 wound = moderate distance (3-6m), can cause multiple organ perforations Type 3 wound = "point-blank" range, or <3m, cause massive tissue destruction.

What are the RBC cutoffs for positive DPL?

Essentially, for all blunt trauma, RBC >100 000 is positive. For penetrating trauma, still RBC >100 000 is positive, EXCEPT for low chest stab wounds and any GSWs, where risk is high so threshold is lower (5-10 000 RBCs).

What is the estimated risk of diaphragm penetration from a left lower chest stab wound?

Estimated at 17% These are high risk injuries, and should be managed conservatively (close observation, advanced imaging, and low threshold to progress to laparotomy).

What are the views that make up the FAST exam? What makes up the E-FAST?

FAST = Morrison's pouch, the splenorenal recess, and the pouch of Douglas E-FAST = normal FAST + pericardial view and lung views to rule out pneumothorax

How does FAST compare in paediatric vs. abdominal trauma?

FAST has lower sensitivity in paediatrics than adults.

How does the presence of pelvic fracture change the algorithm in the setting of blunt abdominal trauma?

Main difference is that in the unstable patient, want to determine ASAP if the instability is related to the pelvic # or an active intraperitoneal hemorrhage. Immediate U/S or DPL to identify intraperitoneal hemorrhage. If present, straight to laparotomy. If not present, consider angioembolization + pelvic # fixation to gain hemodynamic stability. If no intraperitoneal hemorrhage, then continue as usual with other imaging to identify other injuries and determine need for OR vs. observation vs. discharge.

Under what circumstances is angiography recommended in the setting of acute abdominal trauma?

Only role is if done THERAPEUTICALLY (i.e. to identify a hemorrhaging vessel and embolize it). Typically done for hemodynamially unstable patients due to pelvic fracture, or high grade unstable splenic lacerations that require definitive correction of the bleeding vessel.

Describe the shift in management approach for high grade liver and spleen injuries in the setting of abdominal trauma.

Previously, any liver/spleen injury in abdominal trauma necessitated laparotomy. However, this was felt to cause more harms due to the number of unnecessary laparotomies. Therefore, current management is shifting towards a more conservative approach, with observation even for high grade liver and spleen lacerations in some cases.

How should a patient be positioned for decubitus positioning to identify free air in the peritoneum? What is the appearance on XR?

Should always be placed LEFT lateral decubitus (rather than right), to avoid confusion between free air vs. gastric bubble. In left lateral decubitus, will see air rise to the superior flank and outline the lateral liver edge.

What organ is the most commonly injured in the setting of blunt abdominal trauma? Second most common?

Spleen = most commonly injured organ from blunt abdominal trauma. Liver is second most commonly injured.

What are the 2 most commonly injured abdominal organs in the setting of stab wounds? What are the 3 most commonly injured abdominal organs by GSWs?

Stab wounds: 1) liver 2) small bowel (corresponds with their respective surface area within the abdomen) GSWs: 1) small bowel 2) colon 3) liver

Describe management of Type I, II, and II shotgun wounds to the abdomen.

Type 1 wound = long distance (>6m), usually involves subq tissue and deep fascia only -usually conservative management, unless clearly meet criteria for laparotomy Type 2 wound = moderate distance (3-6m), can cause multiple organ perforations -variable management -conservative approach is laparotomy -some advocate for conservative management, as they believe most small puncture wounds of the bowel will heal spontaneously Type 3 wound = "point-blank" range, or <3m, cause massive tissue destruction. -immediate laparotomy

How much free abdominal fluid is required before it becomes detectable with FAST ultrasound?

Typically quoted that FAST can detect 500mL of intraperitoneal fluid, although some studies suggest it can detect as little as 100mL.

How does the sensitivity of U/S compare to CXR for detecting pneumothorax?

U/S is 3x more sensitive than CT for pneumonthorax (60% sensitivity for U/S vs. 20% for CXR).