Which Blunt Trauma Patients Should Be Studied by Abdominal CT?

Transcription

1 MDCT of Bowel and Mesenteric Injury: How Findings Influence Management 4 th Nordic Trauma Radiology Course th Nordic Trauma Radiology Course 2006 Stuart E. Mirvis, M.D., FACR Department of Radiology & Maryland Shock-Trauma University of Maryland School of Medicine Which Blunt Trauma Patients Should Be Studied by Abdominal CT? Hemodynamic stability maintained Unreliable clinical assessment Positive abdominal exam without overt signs (rebound, rigidity) Positive DPL or sonogram (FAST) Suspect retroperitoneal injury Unknown source of blood loss

2 Overview BMI < 0.5% admissions to trauma BMI 3-5% of patients having laparotomy for blunt trauma Clinical signs present < 50% initially DPL variable results for BMI (sensitivity 69%) Sonography - 52% sensitive Non-operative management of solid organ injuries requires high accuracy for BMI Role of CT Is Controversial Role of CT Is Controversial Many literature studies, mainly surgical, cite low sensitivity and high reader dependence (mainly 80 s, early 90s) More recent studies using helical and MDCT indicate consistently higher CT accuracy 75% of respondents to AAST survey use CT most or all of the time for possible BMI Still actively debated (EAST) 13% perforated SB injuries missed by CT # # Fakhry SM, Watts DD, Luchette FA. J Trauma 2003;54:

3 CT of bowel and mesenteric injury 1995 to 2002: 36 cases of BM injury 16 isolated and 20 non-isolated injuries Initial CT scan was abnormal in 74% (17 out of 23), and 83% on retrospect (2 additional cases) CT scans were abnormal (initial and repeat) in 96% (22 out of 23). Free fluid (78%), mesenteric stranding or edema (39%), bowel wall hematoma, or edema (30%). Free air 31%, oral contrast extravasation 15% Sharma et al. The role of computed tomography in diagnosis of blunt intestinal and mesenteric trauma (BIMT). J Emerg Med Jul;27(1): Oral vs. no oral contrast N= 20 patients (500 blunt trauma reviewed) Sensitivity and specificity of CT imaging for the detection of BBMIs were 95.0% and 99.6% CT imaging of the abdomen without oral contrast for detection of BBMIs compares favorably with CT imaging using oral contrast.? Confidence level Allen TL, et al. Computed tomographic scanning without oral contrast solution for blunt bowel and mesenteric injuries in abdominal trauma. J Trauma Feb;56(2):

4 MDCT Technique (16-slice) MDCT Technique (16-slice) 0.75 or 1.5mm X 16mm slice thickness Pitch 1.25 Oral contrast (add rectal for penetrating injury) IV contrast ml (350 mg/ml) Intravenous 6 ml/sec X 15 sec., then 4/sec. X 15 sec. (skull base to pubis) 3-5 mm reconstructions for PACS Use 1mm reconstructed images for reference and MPR, 3D, volumetric studies Diagnostic (operative) CT Signs of Full-thickness Bowel Injury Bowel contrast extravasation Pneumoperitoneum, intramural, intramesenteric air without known or alternative source (20% sensitive) Direct visualization of tear in wall (rare)

5 CT Pneumoperitoneum Consider other sources of air Look for free air beneath anterior abdominal wall, adjacent liver, porta hepatis, between bowel loops More cephalad air in abdomen suggests more cephalad bowel source Look in mesentery, bowel wall, portal vein Use bone or lung settings for search Only about 20% sensitive Distinguish from pneumothorax

6 Pneumoperitoneum: windows & levels for bone or lung Jenunal Perforation Blunt Trauma

7 Was DPL performed? Jejunum: Blunt fullthickness injury

8 Subtle free air: Colon rupture Duodenal rupture

9 Direct rupture of duodenum; free air & hematoma Colon rupture: Intramural air, free air air

10 Intramural duodenal air air delayed duodenal hematoma 4d 4d Oral contrast leak Oral contrast leak Requires oral contrast Spills into low resistance peritoneal space Active bleeding usually dissects into mesentery and has surrounding hematoma Extravasated urine from intraperitoneal bladder rupture can confuse diagnosis (delayed imaging)

11 Oral contrast spillage: OR jejunal perforation Fecal spillage right colon & Lumbar Hernia

12 Indirect Signs of Bowel Injury: Indirect Signs of Bowel Injury: Bowel wall thickening (subjective) Adjacent mesenteric infiltration or hematoma Dilated, fluid-filled loops - atonic Increased wall contrast enhancement Free fluid of? source Bowel Wall Thickening Normal bowel 1-2 mm partially distended; 3-4 mm when collapsed Seen in proximal small bowel most commonly 5-6 mm mild thickening, 7-8mm moderate, >8 mm marked Contusion localized thickening involving adjacent loops (prox. jejunum) No other findings equals contusion Bowel wall hematoma can co-exist

13 Bowel contusion & free fluid: Full-thickness bowel injury

14 Bowel Contusion Jejunal perforation at OR

15 Horse kicks broom into abdomen! Duodenal transection direct diagnosis Delayed colonic hematoma; Pt. on anticoagulants

16 Bowel Wall Enhancement Bowel Wall Enhancement Patchy increased density in bowel with thickened wall Often seen with mesenteric edema Mechanism: slowed perfusion, leaky capillaries, re-perfusion phenomenon Mandates careful follow-up Thick-walled enhancing bowel

17 Enhancing small bowel wall Intraperitoneal Fluid Intraperitoneal Fluid Always measure fluid density Trace amount occasionally seen in cul-desac of women of child-bearing years May be the only sign of injury to bowel/mesentery or solid organ (20%+) Larger amounts of fluid in more locations increases chance of injury Mesenteric triangles (bowel mesenteric origin likely)

18 Pelvic Fluid: Male CT of Mesenteric Injury CT of Mesenteric Injury Active bleeding Hematoma Infiltration (misty, hazy) Triangle sign of intramesenteric fluid Fascial thickening Difficult to distinguish operative from non-operative lesions

19 Mild mesenteric contusion (misty- hazy) Mesenteric hematoma: renal infarct

20 Colonic contusion with mesenteric tear -hematoma Colonic contusion with mesenteric tear -hematoma Active mesenteric bleeddelayed diffusion

21 Active mesenteric bleed: Sentinel clot Mesenteric hematoma: Sentinel clot clot

22 Active Mesenteric Bleed Delayed Active bleeding mesenteric hematoma; Tear at at root of of mesentery

23 Active mesenteric bleed Enveloping Mesenteric Hematoma

24 Intramural gastric hematoma Management for Indirect CT Findings Serial physical examination * F/U CT 6-8 hours Follow-up sonography (same examiner) Diagnostic peritoneal lavage (WBC, bile) Exploration

25 MVC: Abdominal Pain- initial CT Follow-up CT 10 hr. Jejunal rupture in OR

26 Mimics & Masks of Bowel Injury Mimics & Masks of Bowel Injury Shock bowel: follows prolonged hypotension or cardiac arrests Diffuse bowel wall thickening Patchy increased enhancement Dilated, fluid-filled bowel Small bowel mainly involved Mesenteric edema common Usually flat IVC, renal veins May see increased renal and adrenal enhancement, decreased spleen density

27 Shock Bowel Shock Bowel Shock Bowel Shock Bowel

28 Shock Bowel: Small bowel & colon Shock bowel

29 Shock Bowel Shock Bowel Mimics & Masks of Bowel Injury Mimics & Masks of Bowel Injury Increased venous return pressure Over resuscitation, cardiac tamponade, tension pneumothorax, hematoma compressing IVC Distended IVC and renal veins Diffuse edematous small bowel and mesentery Often retroperitoneal, pericholecystic edema and peritoneal fluid Rarely involves colon

30 Pericardial Tamponade Increased CVP Periportal lymphedema

31 Increased CVP Small bowel edema Summary What are the CT findings of bowel and mesenteric injury? Which of those findings indicates need for surgical intervention? observation? anxiety? What are the major concurrent trauma findings that mimic or mask signs of bowel and mesenteric injury?

32 Thank You