1. Intestinal trauma Vittorio Miele S. Camillo Hospital – Rome (I)
Emergency Radiology Department

2. Summary Blunt mesenteric and bowel trauma
CT findings of bowel injuries
CT findings of mesenteric injuries
I’m going to talk about the blunt mesenteric and bowel trauma, with the special focus on the CT findings
Conclusions

3. Summary Blunt mesenteric and bowel trauma Epidemiology Sites
Pathogenesis
Clinics
Imaging
CT findings of bowel injuries
CT findings of mesenteric injuries
Let’s start with the epidemiology, sites, pathogenesis, clinical findings and the role of Imaging techniques
Conclusions

4. Epidemiology
Detected in 5% of blunt abdominal trauma patients at laparotomy.
Third most commonly injured abdominal organ following blunt trauma.
Isolated bowel and mesenteric lesions are thought to be about 3 times more frequent.
Those trauma are detected in 5% of blunt abdominal trauma patients at laparotomy and are the third most commonly injured abdominal organ following blunt trauma. Isolated bowel and mesenteric lesions are thought to be about 3 times more frequent.

5. Sites: JEJUNUM-ILEUS Most frequent site: 70%.
Near to the areas of fixation: Treitz ligament and ileocecal valve.
Lesions occurs most frequently in the antimesenteric side of the intestinal wall.
Delayed signs of peritoneal irritation: intestinal content (++jejunum) has neutral pH, low bacterial, not enzimatically active.
Most frequent site is JEJUNUM-ILEUS tract (in seventy percent of cases) and, within this tract, expecially near the areas of fixation: Treitz ligament and ileocecal valve. Lesions occur most frequently in the antimesenteric side of the intestinal wall. Signs of peritoneal irritation are delayed; it depends on the intestinal jejunal content that has neutral pH, low bacterial power, and it is not enzimatically active. 5

6. Sites: COLON Less common: 20% (Transverse, sigmoid and ciecal colon)
Transverse colon: most common. Intramural hematoma or serosal lesion, without faecal contamination.
Right and descending colon: more significant lesions. Full thickness laceration, mesenteric avulsion, devascularization.
Less common site is colon in twenty percent of cases. Transverse colon is the most common site with intramural hematoma or serosal lesion, without faecal contamination. In rigth colon and descending colon lesions are more significant, for example full thickness laceration, mesenteric avulsion, devascularization. 6

7. Sites: DUODENUM Uncommon: 10%.
D2 and D3: compression against the spine.
Duodenal perforation: ++ retroperitoneal.
Perforation: endoluminal gas/fluid leakage in different anatomical spaces
Right anterior pararenal space
Peritoneal space
Much less common site is Duodenum (about ten percent). The cause can be the compression against the spine of descending and trasverse duodenum. Duodenal perforation is most frequent in retroperitoneum. In case of perforation a tipical sign is leakage of gas and fluid in different anatomical spaces: the right anterior pararenal space and the peritoneal space

8. Pathogenesis Motor vehicle accident Assault Fall Car accident
Motorcycle accident
Car vs. pedestrian
Bicycle accident
Assault
Fall
Pathogenesis: Most common causes of blunt mesenteric and bowel trauma are: Motor vehicle accidents, including car accidents, Motorcycle accidents, cars versus pedestrians, Bicycle accidents. Furthermore, Assaults and Falls 8

9. Mechanism of injury
Abrupt deceleration determinates sharing forces at fixed sites (mesentery root, anatomical points of fixation, acquired adhesions)
Compression from a direct force on GI tract
Sudden increase in endoluminal pressure (burst injuries)
Mechanisms of injury are: Abrupt deceleration determinates sharing forces at fixed sites (mesentery root, anatomical points of fixation, acquired adhesions). Other causes are the compression from a direct force on gastrointestinal tract and sudden increase in endoluminal pressure (in burst injuries). 9

10. Clinical evaluation
Challenging clinical diagnosis: findings are subtle, aspecific and time-developing.
Clinical findings: abdominal pain, signs of peritoneal irritation.
Abdominal evaluation unreliable in patients with concomitant head and spinal trauma.
Clinical evaluation is difficult. Clinical signs are aspecific and change during the time: they are abdominal pain and signs of peritoneal irritation. Abdominal evaluation is unreliable in patients with concomitant head and spinal trauma. 10

11. Imaging’s role To detect bowel and mesenteric injuries
To distinguish significant lesions that require surgical intervention from those that can be managed non surgically
Delayed diagnosis  increased morbidity and mortality
hemorrage: rupture of mesenteric vessels
peritonitis (sepsis): bowel perforation
The role of imaging is: To detect bowel and mesenteric injuries and To distinguish significant lesions that require surgery from those that can be managed non surgically. A point to remember is that the delayed diagnosis causes increased morbidity and mortality in case of Hemorràge due to rupture of mesenteric vessels and peritonitis due to bowel perforation 11

12. MDCT Diagnostic test of choice in hemodynamically stable patients.
More sensitive and specific than DPL, FAST and clinical examination; evaluates retroperitoneum and skeleton.
MDCT: reduces time required and motion artifacts, improves blood vessel opacification and CE of solid organs and bowel walls.
Multidetector CT is the first choice technique in the case of hemodynamic stability, because it is more sensitive and specific than peritoneal lavage, FAST ultrasonography and clinical examination. It allows to evaluate also retroperitoneum and skeleton. Multidetector CT reduces examination time required, reduces motion artifacts, improves blood vessel opacification and solid organ and wall bowel contrast enhancement with high sensitivity and specificity.
Accuracy: still controversial
Sensitivity: 64-95%
Specificity: % 12

13. MDCT Unhenanced abdomino-pelvic scans.
Biphasic study (arterial and venous phase) after intravenous injection of iodinate contrast material.
Slice thickness and reconstruction interval: 1 mm.
Post-processing elaboration: multiplanar reformation images and 3D reconstructions
We begin the CT scan with unhenanced abdominopelvic scans. We continue with biphasic study after intravenous injection of iodinate contrast material in the arterial and portal venous phases. The slice thickness is less than 5 millimeters and we use to reconstruct images with 1 millimeter slice thickness at 1 millimeter interval. The CT examination is completed in the post-processing , with multiplanar imàges. 13

14. MDCT
The axial scan, coronal and 3-dimensional reconstructions show a large right retroperitoneal hematoma, with active bleeding, from mesenteric vessel rupture. 14

15. Oral contrast material?
According to the literature, we agree that the use of oral contrast material is not necessary to detect Bowel trauma 15

16. Summary Blunt mesenteric and bowel trauma
CT findings of bowel injuries
Classification
Bowel wall discontinuity
Extraluminal contrast material
Extraluminal air
Bowel wall thickening
Abnormal wall enhancement
Hematoma
Free fluid
Mesenteric infiltration
CT findings of mesenteric injuries
Now we talk about the CT findings of bowel traumatic injuries. Here we have a classification that shows the abnormalities that we can find: bowel wall discontinuity, extraluminal contrast material, extraluminal air, bowel wall thickening, abnormal wall enhancement, hematoma, free fluid, mesenteric infiltration
Casistica clinica 16

17. Bowel traumatic injuries
Major
Minor
Transmural laceration
Incomplete tear (serosal tear)
Bowel contusion
Parietal hematoma
Bowel traumatic injuries are generally classificable in Major and minor injuries. Major injuries are Transmural laceration, that need treatment with laparotomy. Minor injuries are Incomplete tear (serosal tear), Bowel contusion and parietal hematoma, that allow conservative treatment and require follow up
CONSERVATIVE
LAPAROTOMY
FOLLOW UP 17

18. Bowel traumatic injuries
Specific signs
Non specific signs
Bowel wall discontinuity
Extraluminal oral contrast material
Extraluminal air
Bowel-wall thickening
Abnormal wall enhancement
Free fluid
Mesenteric infiltration (stranding)
There are specific and non specific signs. Specific signs are: Bowel wall discontinuity, and Extraluminal oral contrast material leakage. Non specific signs are Extraluminal air, Bowel-wall thickening, Abnormal wall enhancement, Unexplained free fluid, Mesenteric infiltration 18

19. Bowel wall discontinuity
Very specific, but uncommon finding.
Small discontinuities, evident only at surgery with careful inspection.
Leakage of enteric content and air bubbles, close to injuried intestinal loop
BWD is a very specific, but uncommon sign.
Small discontinuities are evident only at surgery.
An indirect sign is the leakage of intestinal content and/or air bubblers, that are located close to the rupture of the intestinal loop. 19

20. Extraluminal contrast material
Requires oral contrast material administration
High specificity, low sensitivity (12%).
As we said, extraluminal contrast material leakage is a direct sign of lesion; we can see it as oral contrast outside of the intestinal lumen. This sign has High specificity but low sensitivity. Furthermore, in this case, we can also see extraluminal air. 20
Brofman, N. et al. Radiographics 2006;26:

21. Extraluminal air
Highly specific, but not very sensitive (44-55%) sign of bowel perforation.
Pneumoperitoneum may need a few hours after the trauma to become evident.
In the setting of a duodenal perforation, pneumoretroperitoneum is a more specific sign.
Extraluminal air is a highly specific, but not very sensitive sign of bowel perforation. It is because pneumoperitoneum may need a few hours after the trauma to become evident. In the setting of a duodenal perforation, pneumoretroperitoneum is a more specific sign. A point to remember is that CT is able to demonstrate also small amounts of extraluminal air.
CT is valuable in detection of very small amounts of extraluminal air. 21

22. Extraluminal air …where to find it?
deep to the anterior abdominal wall
anteriorly near the liver/spleen
in the porta hepatis
within mesentery leaves
in the mesenteric veins or portal vein
in the abdominal wall
When I am looking for extraluminal air I have to look at: deep to the anterior abdominal wall, anteriorly to the liver and the spleen, in the porta hepatis, within mesentery leaves, in the mesenteric or portal veins or within the abdominal wall 22

23. Extraluminal air deep to the anterior abdominal wall 23
A common site of air collection is deep the anterior abdominal wall 23

24. Extraluminal air anteriorly near the liver/ spleen
in the porta hepatis
Anteriorly, near the liver or the spleen, as is shown in axial scan. Or in the hepatic hilum, as is shown in the coronal reconstruction. 24

25. Extraluminal air Within mesentery leaves
in the mesenteric veins / portal vein
This is another example of Extraluminal air within mesentery leaves due to rupture of the terminal ileum 25

26. Extraluminal air
in the bowel wall (intramural air): strongly suggestive of complete parietal lesion
In the coronal reconstruction, we can see air bubbles within the duodenal wall; furthermore, free fluid. In axial scan, linear intramural air allows to suspect a major lesion. A point to remember is that intramural air bubble is strongly suggestive for complete parietal lesion. 26

27. Extraluminal air in the retroperitoneum 27
In cases of colonic trauma, free air may collect in the retroperitoneum 27

28. Extraluminal air …some causes of free air that we have to remember
DPL prior to CT
mechanical ventilation and pulmonary barotrauma
air via the female genital tract (Falloppian tube)
intraperitoneal laceration of the bladder
misinterpretated PNX
There are some causes of intra or retroperitoneal free air that we have to remember. A diagnostic peritoneal lavage executed prior to CT; mechanical ventilation and pulmonary barotrauma; air via the female genital tract (tubarian); misinterpretated pneumothorax. In these cases a careful search for other findings of bowel injury is mandàtory!
In these cases, a careful search for other findings of bowel injury is mandatory! 28

29. Pseudopneumoperitoneum
Extraluminal air
Pseudopneumoperitoneum
Presence of air confinated to the inner layer of the abdominal wall and external to the parietal peritoneum.
Remember that in some cases air is restricted to the inner layer of the abdominal wall and external to the parietal peritoneum. 29

30. Bowel-wall thickening
Sensitive, but not specific sign: both significant and not significant traumatic lesions, non traumatic hematoma, infective pathology, inflammatory diseases.
75% of transmural lacerations.
Intramural air: full-thickness lesion suspected.
In isolated mesenteric lacerations: interrupted arterial supply or venous drainage.
Bowel wall thickening is a sensitive sign, but it is not specific, because it may be present in significant and non significant lesions, and in infective and flogistic diseases. It occurs on seventy-five percent of transmural lacerations. Intramural air is suggestive of full-thickness lesion. Bowel wall thickening may represènt the only sign of an isolated mesenteric laceration, with interruption of arterial supply or venous drainage. 30

31. Bowel-wall thickening
This finding is significant if:
disproportionate thickening compared to normal appearing segments
bowel wall thickness more than 3 mm with adequate distention of the lumen
circumferential involvement
We can compare disproportionate thickening between different bowel segments. Wall thickness more than three millimeters is significant if lumen is adequately distended. Injured bowel loops show a circumferential involvement. On the left, we have jejuneal wall thickening with intramural air bubbles and peritoneal free fluid; it is due to perforation. On the right side, we can see a circumferential wall thickening in a normal bowel (the bowel is not adequately distended) 31

32. Bowel-wall thickening
This is another case of circumferential wall thickening due to a traumatic hernia; stranding of the mesentery. 32

33. Bowel-wall thickening
Due to lack of luminal distention
In this patient the circumferential wall thickening is due to lack of luminal distention (there is gastric distention) 33

34. Bowel-wall thickening
Shock bowel: systemic hypoperfusion
Small bowel. Diffuse, asintomatic, reversible
Systemic hypoperfusion, increased permeability, interstitial leak of contrast material lead to diffuse thickening and marked contrast enhancement of the bowel walls
Dilated fluid-filled loops (due to failed resorption capacity)
Flattened ICV and renal veins,  renal and adrenal CE,  splenic CE
Shock bowel happens in case of systemic Hypoperfusion. Infact we can find diffuse small bowel wall thickening and marked contrast enhancement of the bowel walls; this is caused by increase of parietal permeability, interstitial leakage of contrast media. Loops will be dilated and fluid – filled. Others signs that we can see are: flattened inferior caval vein and renal veins, increase of renal and surrenal contrast enhancement, and decrease of splenic contrast enhancement 34

35. Bowel-wall thickening
Shock bowel: systemic hypoperfusion
Shock bowel happens in case of systemic Hypoperfusion. Infact we can find diffuse small bowel wall thickening and marked contrast enhancement of the bowel walls; this is caused by increase of parietal permeability, interstitial leakage of contrast media. Loops will be dilated and fluid – filled. Others signs that we can see are: flattened inferior caval vein and renal veins, increase of renal and surrenal contrast enhancement, and decrease of splenic contrast enhancement 35

36. Bowel-wall thickening
Systemic volume overload (fluid resuscitation with hyperidratation) can result in bowel wall and mesenteric edema.
No  parietal CE.
Distended ICV and renal veins.
Retroperitoneal fluid and periportal lymphedema.
We have to remember that bowel wall thickening and mesenteric edema can result in case of hyperidratation but in this case we have some differences. Infact, there is not increase of parietal contrast enhancement, we have a normal aspect of inferior vena cava and renal veins; we can find Retroperitoneal fluid and periportal lymphèdema. 36

37. Abnormal wall enhancement
Causes: local vascular compromise or systemic hypoperfusion
Mechanism: hypoperfusion, increased permeability, parietal thickening and hyperdensity as a consequence of interstitial leak of contrast material
Empiric assessment: compare bowel loop wall to psoas muscle or adjacent blood vessels
Remember that causes of abnormal wall enhancement are local vascular compromise or systemic hypoperfusion.
Pathogenetic mechanisms are hypoperfusion, increased permeability, parietal thickening and hyperdensity due to interstitial leak of contrast material.
Empiric assessment of wall enhancement could be comparing it to psoas muscle or blood vessels.
Here are shown two cases of abdominal trauma with small bowel wall thickening and abnormal wall enhancement 37

38. Abnormal wall enhancement
Reduced or absent parietal contrast enhancement is a highly specific sign of intestinal ischemia.
Motorbike accident: lack of contrast enhancement in distal jejunum caused by mesenteric lesion and bowel devascolarization.
Increased wall thickness and wall enhancement in proximal jejunum.
Stranding of mesentery. 38
Brofman, N. et al. Radiographics 2006;26:

39. Intramural Hematoma Circumferential or eccentric parietal thickening
Rare in the large bowel
Conservative treatment: resolution in 1-3 weeks
Signs of intramural Hematoma are: Circumferential or eccentric parietal thickening. It is Rare in the large bowel. Conservative treatment is performed: usually the resolution occurs in one-three weeks 39

40. Duodenal hematoma Child abuse !!! Parietal thickening
Fluid in the right anterior pararenal space.
Duodenal perforation: Gas or extraluminal oral contrast in the right anterior pararenal space
In duodenal hematoma it is possible to see the presence of fluid in the right anterior pararenal space, but there isn’t leakage of gas or extraluminal oral contrast in the right anterior pararenal space, that is more significant for duodenal perforation.
Child abuse !!! 40

41. Duodenal hematoma
Here we have an example of duodenal hematoma with eccentric parietal thickening. There is not periduodenal fluid and air. 41

42. Duodenal hematoma
Another case with duodenal hematoma and little amount of periduodenal fluid but no free air near the loop and in the right anterior pararenal space 42

43. Free fluid CT is able to detect even small amounts of free fluid
Can be the only sign of a mesenteric and bowel or solid organ traumatic lesion (20%).
Hemoperitoneum in absence of a solid organ lesion: suggestive of bowel or mesenteric laceration (check out an intraperitoneal bladder rupture!).
A small amount of fluid in the Douglas is a normal physiologic finding in the young female.
Free fluid can be the only sign of a mesenteric, bowel and solid organ traumatic lesion. In absence of solid organ lesion, hemoperitoneum can be suggestive of bowel or mesenteric laceration. Remember that small amount of fluid in the Douglas space is a physiologic finding in the menstruating female. Computed Tomography is able to detect even very small amounts of free fluid.
CT is able to detect even small amounts of free fluid 43

44. Free fluid
Location
Poligonal collections within the mesentery leaves and close to intestinal loops are more likely related to mesenteric or bowel injury
In hepatic and splenic lacerations hemoperitoneum distributes in peritoneal recesses
Hemoretroperitoneum: more specific for duodenal/colic injuries
We have to look for free fluid as poligonal collection within mesentery leaves: in this case it is more likely related to mesenteric or bowel injury. Fluid collections in peritoneal recesses are frequently related to hepatic/splenic injuries. Hemoretroperitoneum is a sign more specific for duodenal and colic injuries. 44

45. Free fluid Densitometry
low (<20 UH): extravasation from small bowel (= gallbladder, bladder)
intermediate (>25 UH): hemoperitoneum
high (120 UH): oral contrast material or vascular bleeding
The densitometry can help to indicate the origin of a fluid collection: low density (until twenty Hounsfield unit): is suggestive of extravasation from small bowel (the same from gallbladder and bladder); intermediate density (more than twentyfive Hounsfield Unit): is suggestive of hemoperitoneum; high density (about one hundred twenty Hounsfield Unit ): is suggestive of oral contrast material or vascular bleeding. Remember that: Blood attenuation is time-depending. Blood can dìluite with other extraluminal fluids. Less attenuating fluid can be related to low hematocrit. Ascite, bile
Blood attenuation is time-depending (> 48h).
Blood can diluite with other extravased fluids: ascite, urine, bile or intestinal contents.
Less attenuating fluid correlated to low hematocrit 45

46. Free fluid Poligonal collections Close to intestinal loops 46
In these two cases of mesenteric injuries there are high density fluid collections close to the sixth liver segment and intestinal loops. 46

47. Mesenteric infiltration
Infiltration of mesenteric fat: 65-70% of isolated bowel lesions.
Associated to parietal thickening: highly suggestive of major intestinal injury.
Infiltration of mesenteric fat: is present in sixtyfive-seventy percent of cases of isolated bowel lesions. It is usually associated to parietal thickening: this sign is highly suggestive of major intestinal injury. 47

48. Summary Blunt mesenteric and bowel trauma
CT findings of bowel injuries
CT findings of mesenteric injuries
Classification
Active bleedings
Hematoma
Intramesenteric fluid collections
Mesenteric infiltration
Let’s talk about CT findings of mesenteric traumatic injuries.
Conclusions 48

49. Mesenteric traumatic injuries
Major
Minor
Active bleeding
Full-thickness mesenteric tears
Mesenteric avulsion with ischemic bowel
Focal contusion
Partial thickness laceration
Mesenteric hematoma
There are major and minor signs. Major signs are: Active bleeding, Full-thickness mesenteric tears, Mesenteric avulsion with ischemic bowel. In these cases laparotomy is necessary. Minor signs are: Focal contusion, Partial thickness laceration, Mesenteric hematoma. In these cases observation and follow-up can be helpful.
LAPAROTOMY
OBSERVATION 49

50. Mesenteric traumatic injuries
Specific findings
Non-specific findings
Active bleeding within the mesentery
Mesenteric hematoma
Intramesenteric “poligonal” fluid collections
Mesenteric infiltration (stranding)
We have to consider Specific findings of mesenteric trauma as Active bleeding within the mesentery and Mesenteric hematoma. And Non specific findings, as Intramesenteric “poligonal” fluid collections and mesenteric infiltration. 50

51. Active bleeding
Extravasation of IV contrast from mesenteric arterious or (less commonly) venous vessels: major vascular traumatic lesion.
As we said , active bleeding is a specific sign of mesenteric trauma. Here we have an example of Extravasation of contrast medium from mesenteric arterial vessels. This finding indicates a major vascular traumatic lesion. 51

52. Active bleeding Commonly associated with a bowel wall injury (1/3).
The mesenteric side of the wall is more prone to vascular injuries.
Strongly indicates the potential for a vascular compromise of the bowel
Active bleeding is Commonly associated with a bowel wall injury.
Remember that the mesenteric side of the wall is more prone to have vascular injuries.
Furthermore, active bleeding strongly indicates the potential for a vascular compromise of the bowel.
Markers show active bleeding in the left abdominal space 52

53. Active bleeding
Two different cases with active bleeding in the left abdominal space and in the retroperitoneal paraaortic space 53

54. Sentinel clot sign
Relatively highly attenuating and heterogeneous fluid (clot) that tends to accumulate near the site of injury.
Sometimes is possible to see the Sentinel cloth sign, that is easier to appreciate in not enhanced scans. It is a relatively higly attenuating and heterogenous fluid that tends to accumulate close to the site of injury. 54

55. Hematoma Specific sign of mesenteric vascular laceration
Surgical management is not always required
Active bleeding? Arterial and delayed scans!
Hematoma is a specific, but minor sign, of mesenteric vascular laceration. Surgical mànagement is not always required. To demonstrate Active bleeding we have to perform both arterial and delayed scans! In this case, unenhanced CT shows a large mesenteric hematoma of the left abdomen; hematoma is well seen also in the enhanced scan. You can see also active bleeding 55

56. Hematoma
Large retroperitoneal hematoma with active bleeding 56

57. Intramesenteric collections
Triangle-shaped or poligonal
Intramesenteric fluid collection in a case of mesenteric injury: the collection has a triangolar or poligonal shape. 57

58. Mesenteric infiltration
Inhomogeneus increased attenuation within the mesentery.
Highly sensitive, but non specific sign
Mesenteric +/- bowel injury
Small hemorragic areas or inflammatory response.
Mesenteric infiltration is a highly sensitive but not specific sign of mesenteric and bowel injury: in this case we can find: Inhomogeneus increased attenuation of mesenteric fat associated with fluid collections in paracolic spaces. Mesenteric infiltration could represent small hemorragic areas or inflammatòry respònse 58

59. Mesenteric infiltration
Mesenteric infiltration with Inhomogeneus increased attenuation 59

60. Summary Blunt mesenteric and bowel trauma
CT findings of bowel injuries
CT findings of mesenteric injuries
We go to conclude
Conclusions 60

61. Conclusions Abdominal trauma: should not consider solid organs only.
Traumatic bowel and mesenteric lesions: isolated or associated to solid organ lesions.
In the presence of abdominal solid organ lesions and pelvic fractures check the nearby territories for addictional bowel and mesenteric lesions.
Abdominal trauma is not to be considered to regard solid organs only. Infact we have also to look for Traumatic bowel and mesenteric lesions: isolated or associated to solid organ lesions. In case of abdominal solid organ lesions or pelvic fractures check the nearby territories for discovering addictional bowel and mesenteric lesions. 61

62. Conclusions Parietal discontinuity Active bleeding Surgery
Pneumoperitoneum
Parietal thickening
Free fluid
Mesenteric hematoma
Combination of signs
Clinical/laboratoristic re-assessing
In case of : Parietal discontinuity and/or Active bleeding: operative treatment Is mandàtory. In case of : Pneumoperitoneum, Parietal thickening, Free fluid, Mesenteric hematoma: There are more choises. Consider the Combination of signs, the Clinic and laboratoristic re-assessing. It is possible to perform a Laparoscopy or Repeat CT to re-evaluate the patient.
Repeat CT
Laparoscopy 62