Imaging of Abdominal Trauma


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Imaging of Abdominal Trauma

  1. 1. Imaging of Abdominal TraumaRathachai Kaewlai, MDRamathibodi Hospital, Mahidol University, BangkokEmergency Radiology Minicourse 2013Slides available at or
  2. 2. Introduction•  Abdominal injuries common in multiply-injured patients (20%-40%)•  High death rate, similar to head trauma•  Can be blunt or penetrating– Blunt compressive or deceleration forces– Penetrating: shrapnel, gun shot, blast
  3. 3. Introduction•  Different forces  different types of injuries– Deceleration force  vessel injuries– Compression force  “package” injuries•  Each organ reacts differently to forces– Solid organs lacerate, contuse, infarct– Hollow organs perforate
  4. 4. Potential Means to AssessAbdominal Injuries•  Physical examination: poor sensitivity (<50%)•  Diagnostic peritoneal lavage (DPL): now obsoleteowing to limited accuracy and invasiveness•  Imaging has already replaced DPL–  Ultrasound (FAST): hemoperitoneum–  CT: hemoperitoneum, solid/hollow viscus injuries, activeextravasation/vascular injuries
  5. 5. “Abdomen”•  Anterior: nipple line to groin crease•  Posterior: tips of scapulae to glutealskin crease•  Three basic regions of abdomen–  Peritoneal cavity + intrathoraciccomponent–  Retroperitoneum–  Pelvis
  6. 6. Blunt Abdominal Trauma•  Motor vehicle collision (MVC, ~75%),motorcycle crashes (MCC), pedestrian-automobile impacts, falls and assaults•  Multiple different organ injuries•  Major complications: peritonitis,hemorrhagic shock and death•  Two categories:– Solid organ injuries– Hollow organ injuries
  7. 7. Blunt abdominal trauma evaluation Hemodynamically stable  Hemodynamically unstable FAST CT FAST/DPL Positive  Negative Laparotomy Positive Negative Positive Negative Search for other sourcesof hemorrhage Consider discharge Minor injury Observation Major, nonoperative ICU observation Operative Laparotomy Observation Repeated FAST CT 
  8. 8. Penetrating Abdominal Trauma•  Foreign object pierces skin. Gunshot wounds (GSW),stab wounds•  External appearance of penetrating wound does NOTdetermine extent of internal injuries•  Define trajectory of penetrating wound and consider allpossible internal injuries•  Complications: hemorrhagic shock•  Organs injured: penetrating > blunt trauma = SB, colon/rectum, stomach, pancreas, diaphragm
  9. 9. Penetrating abdominal trauma evaluation Hemodynamically stable  Hemodynamically unstable Laparotomy FAST Positive Negative Stab Wound  GSW To Back/flank – CT indicated Anterior – CT considered Thoracoabdominal – CT considered  Shotgun to back/flank – CT indicated Shotgun to anterior – Laparoscopy/otomy Bullet (higher velocity) – Laparotomy  
  10. 10. Focused Assessment withSonography for Trauma (FAST)•  Been used for over 30 years•  Bedside screening to aid clinicians in identifyingfree fluid in thorax or abdomen•  Initially designed to focus primarily on detectionof free fluid – now modified to detectpneumothorax, quantification of fluid•  Sensitivity 80-90%, specificity 95-100% for freefluid
  11. 11. Anatomical Considerations•  Site of fluid accumulation depends onposition of patient and source of bleeding•  Free fluid in dependent compartments–  RUQ  Morison’s pouch  right paracolic gutter pelvis–  LUQ  subphrenic space  splenorenal recess left paracolic gutter  pelvis–  Pelvis = rectovesical pouch (M), pouch of Douglas (F)
  12. 12. Scanning Techniques•  Sequential– Pericardium– Perihepatic– Perisplenic– Pelvis•  Standard or microconvex probe•  Transthoracic view follows standard
  13. 13. FASTPERICARDIUM•  Global cardiacfunction•  Chamber size•  Normal pericardium =white line surroundingheart•  Sweeps anterior-posteriorPERIHEPATIC•  Right pleural effusion,free fluid in Morison’spouch, free fluid inparacolic gutter•  Mid-axillary linebetween 8th-11th ribswith oblique scanningplane
  14. 14. FASTPERISPLENIC•  Left pleural effusion, freefluid in subphrenic spaceand splenorenal recess,free fluid in left paracolicgutter•  Left diaphragm, spleen,left kidneyPELVIC•  Longitudinal andtransverse views•  Free fluid in anteriorpelvis or cul-de-sac•  Ideally should be donebefore Foley•  Differentiate partially filledbladder with free fluid by–  Emptying bladder (Foley)or–  Retrograde bladder filling
  15. 15. Hemopericardium•  Anechoic stripe surrounding the heart within parietaland visceral layers of bright hyperechoic pericardial sac•  Especially helpful in penetrating trauma•  Classic clinical signs found in < 40% of cases withproven cardiac tamponade•  Bedside cardiac US–  Reduces time of diagnosis and disposition to OR–  Increases survival•  Sensitivity 100%, specificity 96.9%, accuracy97.3%
  16. 16. Free Pleural Fluid•  Anechoic stripe above diaphragm•  US is at least comparable to CXR•  Minimum fluid needed–  Upright CXR 50-100 mL–  US 20 mL•  Differentiation of fluid from pleural thickening andlung contusion•  Complement CXR in diagnosis of hemothorax insupine patient
  17. 17. Hemoperitoneum•  Anechoic stripe inMorison’s pouch,paracolic gutter,splenorenal recess,left subphrenic space,pelvis
  18. 18. US Features of Organ Injuries•  Not specific goal of FAST to detect organ injury•  Acute laceration–  Fragmented areas of increased or decreased echo•  Contained intraparenchymal or subcapsularhemorrhages–  Isoechoic or slightly hyperechoic (difficult to detect)•  Low sensitivity esp splenic injury
  19. 19. Pitfalls of FAST•  Contraindication (when emergent Sxneeded)•  Overreliance on FAST: esp negative ones•  Limitations of FAST:– Morbidly obese– Massive subcutaneous emphysema•  Pregnancy•  Technical difficulties
  20. 20. How FAST Affects OtherDiagnostics•  Reduce number of DPL•  Reduce number of CT•  No change to patient’s risk•  Cost
  21. 21. Detection of Pneumothorax•  Pneumothorax occult on CXR in 29-72%•  Extended FAST (EFAST) can identifypneumothorax before CXR•  Best resolution of pleural interface with high-resolution probe and small footprint but mostpractical using same probe as FAST•  Identify contiguity of visceral and parietal pleurausing simple US signs–  Normal = lung sliding (B), seashore sign (M mode)–  Abnormal = loss of lung sliding (B), stratosphere (M),lung point (B & M)
  22. 22. Detection of Pneumothorax•  “Air rises, water descends”– Dependent disorders: effusion, consolidation– Nondependent disorders: pneumothorax,interstitial process
  23. 23. Normal Appearance:Evaluate for Pneumothorax•  Sagittal view at mid-clavicular line “bat-sign”–  Lung sliding?–  A-line sign?–  Lung point?
  24. 24. Detection of Pneumothorax•  Normal lung sliding–  Twinkling at level of pleuralline in real time–  Sliding of visceral againstparietal pleura–  Seashore sign on M mode–  Avoid using filters that reducenoiseBright pleural line that moves on realtime scanningseashoreSeashore sign on M mode
  25. 25. Pneumothorax:Loss of Lung Sliding•  Sensitivity 80-100%(lower in trauma)•  Specificity 83-100%•  Real-time US•  M mode = Barcode orstratosphere sign•  “Lung point” most specificsign (alternating areas ofbarcode and seashoresigns)Barcode or stratosphere sign
  26. 26. Algorithm:Looking for Pneumothorax on USLungsliding?YesPneumothoraxruled outNoB-lines?YesNoLungPoint? No Use othertoolsYesPneumothoraxAdapted from Lichtenstein D.
  27. 27. Pitfalls of US on Pneumothorax•  “Loss of lung sliding” alone is not specificfor pneumothorax– Pleural adhesion/thickening– Atelectasis– Lobec/pneumonectomy– One-lung intubation•  Look for “Lung Point” for specificity•  Comparison with contralateral lung
  28. 28. FAST vs. CTFAST CTAim for Detection of hemoperitoneum Detection ofhemoperitoneum, organinjuriesAccuracy (forhemoperitoneum)88% Nearly 100%Accuracy (fororgan injuries)74% Nearly 100%Missed rate 15% of hemoperitoneum. Up to25% of liver/spleen, most renal/pancreas/bowelBenefits Fast, bedside, no patient prepneeded, no risk of IV contrastissuesMore accurate, guidenon-operativemanagementACR*RecommendationDone first and only ifhemodynamic unstable beforegoing to ORDone if hemodynamicstable*The American College of Radiology
  29. 29. When to do CT•  Blunt abdominal trauma– Stable patients with positive FAST– Stable patients with negative FAST butsuspicious for injuries (by clinical or labs)•  Penetrating abdominal trauma– Stable patients with injury to back & flank– (stable patients with thoracoabdominal &anterior stab wounds)
  30. 30. At Time of ReceivingConsultation•  Must know mechanism of trauma– Affecting use of contrast•  Review portable CXR and pelvic XR– Anything obvious been treated?– Signs of aortic injury present? Does patientalso need chest CT?– Pelvic fracture? If yes, is hematuria present?Does patient need CT cystography?
  31. 31. Review portable trauma CXR…Anything obvious been treated?Inadvertent arterial line placement Left pneumothorax
  32. 32. Patient Preparation for CT•  Hemodynamic – must be stable•  NPO – should not wait•  IV contrast – a must (if conditions allow)•  Oral contrast – no need for routine cases•  Rectal contrast – no need for routine cases•  Renal function test – risk/benefit ratio•  Pregnancy test - yes
  33. 33. CT Technique•  Do whole abdomen!•  No plain scan•  Phases of scanning–  With pelvic fractures: late arterial and portovenouswhole abdomen–  Without pelvic fractures: Late arterial upper andportovenous whole abdomen–  + delays at site of injuries•  If suspicion of TL spine fx, do small FOV axialsand coronal/sagittal reformations
  34. 34. CT Technique•  Helical mode. Thinnest collimation possible andreformatted to 2-2.5 mm for viewing•  120 kV•  Auto MA based on patient size•  Lower dose for non-standard phases (i.e., latearterial, delayed)•  Must have coronal and sagittal reformations
  35. 35. Specific Questions•  R/O bowel injuries–  Oral, IV, rectal contrast•  Penetrating trauma–  Oral, IV, rectal contrast•  R/O bladder injuries (gross hematuria + pelvicfractures = a must do)–  CT cystography using 300-400 cc of 2% contrastinstilled through a bladder catheter and image thepelvis
  36. 36. Concerns of CT•  Radiation dose can be reduced by–  Routine use of automatic tube-current modulation–  Reduce Z-axis (no plain scan or unnecessary delayedscan)–  Use of Adaptive Statistical Iterative Reconstruction•  Maximize cost/benefit ratio–  Use of clinical prediction rule, expert recommendation
  37. 37. Important/Urgent Must-Knows•  Free fluid– Differentiation of blood from other fluid– Differentiation of intra- and extraperitonealblood•  Free air•  Active extravasation / vascular injuries•  Hypoperfusion complex
  38. 38. Free Fluid•  Common findings, seen in 75% of patientswith intra-abdominal injuries•  Determine– Where? (intra- or extraperitoneal)– Type? (blood, urine, bowel content, bile,ascites)– Volume? (minor, moderate, major)
  39. 39. Free Fluid: Where?•  Intraperitoneal fluid: Perisplenic, perihepatic,Morison pouch, paracolic gutters, inframesocolic space,lesser sac, between mesenteric leaves•  Extraperitoneal fluid: pararenal, perirenal,perivesical, pericholecystic spaces•  Two confusing areas– Morison pouch vs. perihepatic– Pelvis vs. anterior prevesical space
  40. 40. Free Fluid: Where?Intraperitoneal Blood Extraperitoneal BloodWraps around liver tip NoLocation of primary organ injury in the peritoneum NoCul-de-sac, mesenteric root Perivesical, anterior paravesical
  41. 41. Free Fluid: Type?•  Always measure HU•  Fluid does notenhance! Changes inattenuation from preto post contrast maybe seen but should beminimal (<5-10 HU)Type HUBlood (acute) 30-45Blood (clot) 50-60Contrast (IV, oral, rectal) 100+Clear fluid (urine, ascites,bile)<15
  42. 42. Free Fluid: TypeurineLow-density free fluid in blunt trauma patient proven to beurine leakage from intraperitoneal bladder on CT cystography
  43. 43. Sentinel Clot Sign•  Blood accumulates adjacentto site of bleeding•  Indirect sign of injury to anadjacent organ even if thelesion could not beidentified•  Orwig D and Federle MP*–  Sentinel clot seen in84% of visceral injuries–  Sentinel clot only clue tobleeding source in 14%•  The rest, CT showedinjury itself (86%)Orwig D and Federle MP. Am J Roentgenol 1989;153:747Denser fluid
  44. 44. Free Fluid: Volume•  You can estimate volumeof blood but this is lessimportant thanhemodynamic status•  Each compartment:Morison, perihepatic andperisplenic, paracolicgutters, pelvisAmount(cc)#compartments with fluidMinor 100-200 1Moderate 200-500 2Large >500 > 2Becker CD et al. Eur Radiol 1998;8:553.Intraperitoneal Fluid Quantity
  45. 45. Free Fluid: Volume•  Difficult to quantifyvolume inretroperitoneal bleedAmount CT CharacterMinor Fascial thickeningModerate Confined to retroperitnealspace adjacent to itsorigin (ie, perirenal,anterior/posteriorpararenal)Large Multiple communicatingretroperitoneal spacesRetroperitoneal Hemorrhage Quantity
  46. 46. ActiveExtravasation•  Jet or focal area ofhyperattenuation (within 10 HUof adjacent major vesselsource) within a hematoma oninitial images that fades into anenlarged, enhanced hematomaon delayed images•  Indicates significant bleeding•  Must be quickly communicatedto the clinician (surgical orendovascular Rx may benecessary)Delayed
  47. 47. Pseudoaneurysm / AVF•  Contained by connective tissue or vessel wall (ie, adventitia).•  Adjacent to a vessel•  Does not enlarge. Same size in all phases•  CECT not reliable to differentiate the two•  >70% of pseudoaneurysms progress to rupture but natural history of AVF isuncertainPseudoaneurysm
  48. 48. Active Extravasation vs.PseudoaneurysmCharacters Active Extravasation PseudoaneurysmEdges Ill-defined DefinedShape Commonly a jet (linear orlayering); may be diffuseor focalOften round or oval; possibleneck adjoining arteryDelayedappearanceIncreased attenuation orsize; possible layeringLess apparent; in isolation,no change in size, similarattenuation with vesselsManagement Urgent embolization orsurgery if significant injurypresent*Urgent or ambulatoryembolization or surgery ifsignificant injury present**Not all injuries must be treated. Small pseudoaneurysms or those amenable to Rx by direct pressure do not
  49. 49. Hypoperfusion Complex•  Flat IVC, small aorta•  Enhanced: adrenals, kidneys, GBmucosa, bowel mucosa•  Hypoenhanced: liver, spleen,pancreas, peripancreatic edemaFlat IVC, small aorta, hyperenhanced kidneys, hyperenhanced GI mucosa, andperipancreatic edema caused by hypoperfusion state from left pelvic ring injuryFlat IVCHyperenhancedGImucosa
  50. 50. Specific Organ Injuries•  Solid intraperitoneal organs•  Retroperitoneal organs•  Hollow organs
  51. 51. Liver and Gallbladder•  Common•  Can be part of RUQ/midline “package injuries”–  Shearing right lobe adjacent to hepatic veins–  Compression left lobe•  Vast majority managed nonoperatively–  Surgery if severe injuries with active bleeding and/or complete destruction of entire hepatic lobe•  Right lobe (75%) > left lobe
  52. 52. •  Periportal tracking common, prob due to..–  Lymphedema following systemic volume overload,tension ptx, tamponade or–  Hematoma obstructing hepatic venous outflow
  53. 53. •  Laceration involving hepatic veins (esp. if large >10 cm focal hypoperfusion) associated withinjuries to retrohepatic IVClacerationExtraperitoneal blood
  54. 54. •  Liver laceration involving hilum–  Repeated CT or US, cholescintigraphy or directcholangiography to detect possible biliarycomplicationslaceration
  55. 55. AAST Organ Injury
  56. 56. Splenic Injury•  Most frequently affected organ in blunt trauma (?)•  Contusion, parenchymal laceration, subcapsularhematoma, perisplenic hematoma, fragmentationof parenchyma and disruption of hilar vessels•  Left lower rib fractures frequently associated•  Perfusion defects due to segmentaldevascularization from vascular pedicle injury canbe difficult to distinguish from contusions or localreactive hypoperfusion in hypotensive patient
  57. 57. •  Contusion = hypodense area within normallyperfused splenic parenchyma
  58. 58. •  Laceration = linear perfusion defect
  59. 59. •  Subcapsular hematoma = lenticular shape withcompression of adjacent splenic paenchyma–  Difficult to confidently see splenic capsule–  Sometimes difficult to distinguish btw subcapsular andperisplenic hematomaImage from
  60. 60. AAST Organ Injury
  61. 61. Nonoperative Management ofSplenic Injury•  Now accepted practice: Success rate 95% inchildren, 70% in adults•  Well-recognized complication = delayed splenicrupture–  No reliable CT finding to predict risk of delayedsplenic rupture–  Even a normal CT cannot exclude possibility ofdelayed splenic rupture
  62. 62. Pancreas•  <2% of blunt abdominal trauma•  Up to 90% multiple organ injuries•  Contusion, superficial or partial laceration,complete transection or disruption•  Can be difficult to diagnose clinically– Delayed complications: recurrent pancreatitis,fistula, abscess, hemorrhage– Risk of abscess/fistula high (25-50%) if ductdisruption (vs. 10% if duct not disrupted)
  63. 63. Pancreas•  Predict the presence or absence of ductaldisruption by depth of laceration andlocation– Grade A, pancreatitis or superficial laceration(<50% pancreatic thickness)– Grade B, deep laceration (>50% thickness) attail– Grade C, deep laceration at head
  64. 64. •  Direct CT signs: Pancreatic enlargement, focal linear non-enhancement, comminution, heterogeneous enhancement (subtleinitially)•  Indirect CT signs: Peripancreatic fat stranding, fluid collections, fluidseparating splenic vein from parenchyma, hemorrhage, andthickening of left anterior pararenal fasciaFocal linear non-enhancementFocal linear non-enhancement
  65. 65. Bowel and Mesentery•  3-7% of blunt abdominal trauma•  Jejunum and ileum (near point of fixation—ICvalve and ligament of Treitz) most common•  Colon: transverse, sigmoid and cecum•  Stomach-rare•  Duodenal injury: 2nd/3rd part in close proximityto spine•  Overall CT sensitivity/specificity 85-95%
  66. 66. •  Direct CT signs: 1) Discontinuity of wall, spillage of contrast orluminal contents into peritoneal or retroperitoneal. 2) Extraluminal air(definite for blunt trauma but not for penetrating trauma)•  Indirect CT signs: 1) Focal bowel wall thickening, streakymesenteric fat, unexplained free fluid between mesenteric loops. 2)Generalized bowel wall thickening nonspecificColonic contrast leakagePerforation site at sigmoid colonBullet
  67. 67. •  Duodenal perforation vs. hematoma–  Perforation  immediate surgery–  Hematoma  conservative•  Helpful if you can give oral contrast immediately beforescanning to see leakagePerforation siteCircumferential wall hematoma
  68. 68. •  Mesenteric injury–  Extravasation of contrast (active bleeding)–  Intramesenteric fluid collections, hemoperitoneum,thickening bowel loops in bowel ischemiaInitial scanDelayed scan withprogressive increase ofextravasation
  69. 69. Adrenal Glands•  2% of blunt trauma cases undergone CT•  Usually unilateral, right sided and a/wipsilateral intraabominal and thorax injuries•  Majority not clinically significant•  Spontaneous resolution in 2 months•  Specific Rx may be needed if: largehematoma compressing IVC, bilateralhematomas result in adrenal insufficiency
  70. 70. •  Round or ovoid, stranding of perirenal/periadrenal fat•  Active bleeding due to injuries to suprarenal arteries•  F/U CT in 2-3 months to ensure resolution if unable to differentiate frompre-existing adrenal mass on trauma CTActive contrast extravasation in adrenal hematomaPortovenousArterial
  71. 71. Kidney and Ureter•  Kidney injury = most common RP injury•  Contusion, laceration, subcapsular hematoma,shattered kidney, renal artery occlusion•  Major renal hemorrhage with minor traumashould raise suspicion of underlying pathology(hydronephrosis, cyst, horseshoe kidney, AML,RCC)•  Macroscopic hematuria + stable  urethralinjury excluded then  CT
  72. 72. •  Renal contusion: focal zones of decreasedenhancement, striated nephrogram because oftemporarily impaired tubular excretionKawashima A, et al. Radiographics 2001
  73. 73. •  Laceration: linear or wedge-shaped hypodense area–  Fracture = involving medial and lateral surface of kidney through hilum–  Shattered kidney = laceration crossing kidney resulting in multiple fragmentsInitial DelayedLacerationActive extravasationhematomahematoma
  74. 74. •  Deep laceration results inurine extravasation•  Delayed scan forconfirmationInitial DelayedExcreted contrast in left ureterUrinomaUrinoma
  75. 75. •  Occlusion of main renal artery (subintimal tear withsubsequent thrombosis) or arterial avulsion•  Cortical enhancement due to patent capsular arteriesoriginating proximal to occlusion should always raisesuspicion of injury to main renal arteryNo enhancement
  76. 76. AAST Organ Injury
  77. 77. AAST Organ Injury
  78. 78. Urinary Bladder•  Most pelvic visceral injuries = bladder andurethra•  Gynecologic injuries rare after blunt trauma•  Urinary bladder 8% of patients with pelvic fx•  Indicators of bladder injury–  Macroscopic hematuria–  Pubic rami fractures–  Hemorrhagic shock upon admission
  79. 79. •  Extraperitoneal rupture–  Direct perforation by bony fragment, rupture of pubovesicalligament near bladder neck after symphysis injury or contusionof distended UB–  Often involves anterior bladder wall near neck–  Conservative RxBladder contrast in anterior perivesical space
  80. 80. •  Intraperitoneal rupture–  More frequently caused by direct perforation of bone fragment (>rupture of distended bladder)–  Plugged by omentum or bowel loops making it difficult to detect–  Surgical RxPerforation siteLow-density free fluid
  81. 81. CT Cystography•  Antegrade bladder filling by excretion of IVcontrast is NOT enough to exclude bladderinjuries•  Absolute indication: pelvic fracture + grosshematuria•  Technique: 300-500 cc of diluted (2%) contrastinstilled through a bladder catheter using gravitydrip, scan pelvis, drain bladder
  82. 82. AAST Organ Injury
  83. 83. Conclusion•  Trauma to abdomen “torso” often in setting ofmultisystem injury•  Choice of imaging depends on hemodynamicsand imaging availability•  CT is the cornerstone in evaluation of stablepatients (impacting management and reducedmortality)•  Tendency toward non-operative managementmakes use of CT for monitoring
  84. 84. Conclusion•  Must know: free fluid, active extravasation,hypoperfusion complex•  IV contrast needed to assess solid visceralorgan and vascular injuries•  Oral and rectal contrast may be needed inpenetrating abdominal trauma•  Antegrade filling of bladder is not enough toimage of suspected bladder injury.