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MDCT in blunt intestinal trauma
European Journal of Radiology 59 (2006) 359–366
MDCT in blunt intestinal trauma Stefania Romano a,∗ , Mariano Scaglione a , Giovanni Tortora a , Antonio Martino b , Francesco Di Pietto a , Luigia Romano a , Roberto Grassi c a
Department of Diagnostic Imaging, “A.Cardarelli” Hospital, 80131 Naples, Italy b Trauma Center, “A.Cardarelli” Hospital, 80131 Naples, Italy c Department “Magrassi-Lanzara”, Section of Radiology, Second University of Naples, 80138 Naples, Italy Received 21 May 2006; accepted 24 May 2006
Abstract Injuries to the small and large intestine from blunt trauma represent a defined clinical entity, often not easy to correctly diagnose in emergency but extremely important for the therapeutic assessment of patients. This article summarizes the MDCT spectrum of findings in intestinal blunt lesions, from functional disorders to hemorrhage and perforation. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Intestine; Trauma; MDCT; Abdomen; CT; Trauma
1. Introduction
2. MDCT technique
Intestinal mesenteric injuries are found in approximately 5% of all patients undergoing laparotomy after blunt abdominal trauma [1]. About 1.3% of patients with blunt abdominal trauma presents bowel injuries, that are frequently associated with abdominal solid organs lesions [2]. Mainly, there are three types of injuries: crush, shearing forces at fixed sites of attachment, burst injuries from increase in endoluminal pressure [2]. These lesions are related to a high morbidity and mortality, representing a diagnostic dilemma either from trauma surgeons and emergency physicians [3]. Actually, a non-operative management is often the treatment of choice for abdominal solid organs lesions from trauma [4], however because missed bowel and mesenteric injuries are possible [4], early diagnosis and treatment are critical to increased the survival rate [5]. Computed tomography (CT) has been initially proposed in the past two decades in the acute clinical setting of patients with abdominal blunt trauma suspected to have bowel and mesenteric lesions, becoming the primary modality for the imaging in these cases [5–9].
In the recent past years, helical CT was considered a sensitive tool in the identification of bowel and mesenteric injury after blunt trauma, providing a wide spectrum of findings [10]. Multidetector row CT (MDCT) examination without oral contrast material seems adequate for depiction of bowel and mesenteric injuries that require surgical repair [11]. Because of the improved image quality provided by the new generation of scanners, results are comparable with previously reported data for single-detector row helical CT with oral contrast material [11]. The acquisition of initial scans without oral contrast material seems to help to meet criteria of safety and efficiency without sacrificing diagnostic accuracy [11]. Pre-contrast abdomino-pelvis scans (5 mm slice thickness) are useful to better characterize the attenuation values of organs and structures in order to detect or rule out hemorrhagic phenomena and to evaluate any post-contrast HU abnormal changes. A biphasic study in arterial and venous phase is indicated especially when active bleeding or major vessels trauma are clinically suspected. In suspicion of low-flux vascular extravasation from minor vessels, a delayed phase may be added to the examination protocol. Acquisition parameters using an optimised ratio between slice thickness and reconstruction interval (i.e.: 3/3 mm acq., back recon. 1/1 mm), may allow a targeted multiplanar reconstruction in the post-processing elaboration.
∗
Corresponding author at: Via G.Fava 28 parco la piramide, 80016 Marano di Napoli, Italy. Tel.: +39 0817426089. E-mail address: [email protected] (S. Romano). 0720-048X/$ – see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2006.05.011
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S. Romano et al. / European Journal of Radiology 59 (2006) 359–366
Fig. 1. In a middle aged patient with blunt torso trauma and thoracic injury (a), intestinal entero-enteric non-obstructive intussusception (b) was noted, not associated to parenchymal organs injury. Following MDCT control at 48th hour from trauma after administration of endoluminal contrast medium through naso-duodenal tube confirmed the finding (c). Resolution of the event was appreciable starting from 1 day later (d).
3. Spectrum of MDCT Findings Computed tomographic findings of bowel injury from blunt trauma include extraluminal free peritoneal or retroperitoneal air, visualization of direct tears in the bowel wall, intra-peritoneal or retroperitoneal free or collected fluid, bowel wall thickening, abnormal bowel wall enhancement, mesenteric infiltration or hematoma, extravasation of enteric or vascular contrast medium, ileus [12,13]. Bowel wall thickening as well as mesenteric infiltration and free intra-peritoneal air seem to be more relevant predictors of bowel injury [13].
3.1. Functional disorders Intestinal distension by fluid without evidence of an effective site of obstruction may be observed in patients with blunt abdominal trauma, although it can be related to intramural hematoma that in rare cases may cause an intussusception of the intestine [14], often as a non-occlusive and transient event (Figs. 1 and 2). Ileus is a less effective predictor of bowel injury from blunt trauma than other more sensitive and specific findings [13], however intussusception from functional disorders caused by trauma requires monitoring to exclude progression of the transient disease into a confirmed intestinal obstruction [15], preferably with abdominal plain film. MDCT-enteroclysis may be an additional useful follow-up technique to study a trauma-related small
intestine disease in the hemodynamically stable conservatively treated patient, to rule out an obstructive lesion, resulting in some cases resolutive for transient disorders (Fig. 1).
3.2. Bowel wall thickening Bowel wall thickening was seen in 60–75% of cases of bowel injury and in 8% of patients with other injuries [5,6,13] and it seems to be more sensitive for bowel injury than free peritoneal air or extravasation of oral contrast medium [5,6]. However, evaluation of this finding can be subjective, with wall thickness superior to 3–4 mm considered as abnormal [6,17,18], whereas most of contributions reported in literature seems not to consider the luminal distension. To assess a bowel wall abnormality in patients with blunt abdominal trauma, some authors suggested to consider the disproportionate thickening of the intestine compared to normal appearing tracts or a bowel wall thickness superior to 3 mm with adequate distension of the lumen [5]. Bowel wall thickening from intramural hematoma is a known evidence of blunt traumatic injury. Frequently only retrospectively diagnosed, it can be noted in all intestinal segments, although if the colon localization is rare, generally conservatively treated with spontaneous resolution [19]. The healing time of an intramural or a perivisceral hematoma may be various, in some cases with delayed complications: a duodenal intramural hematoma from blunt trauma resolved 48 days after trauma in a 14-year-old
S. Romano et al. / European Journal of Radiology 59 (2006) 359–366
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Fig. 2. A 75-year-old patient with thoracic (a) and pelvic (b) lesions from blunt trauma. A colo-colic intussusception was appreciable (c). The transient event spontaneously recovered without symptoms or obstruction.
boy [20], whereas a case of intra-mesenteric traumatic cyst and fibrosis around the duodenum resulting in duodenal obstruction 8 years after injury [21]. 3.3. Abnormal wall enhancement The increased small bowel enhancement has been described as consequence of shock in trauma, in which the intestine is hypoperfused, with increased permeability and parietal thickening and hyperdensity as a consequence of interstitial leak of contrast medium [22]. Distension of the involved intestinal
segment is related to the accumulation of intraluminal fluid, presumably due to failed resorption capability [22]. It is important to note that these findings related to hypoperfusion cannot be noted in large bowel, suggestive of the lower oxygen demand or a less efficient shunting of blood away from this intestinal tract [22]. Evaluation parameters for wall enhancement may be the reference to the psoas muscle or that of adjacent vessels attenuation [23]. The isolated hyperdensity of the intestinal mucosa from blunt abdominal injury has been reported [5]. In presence of a major accident, the absence of reperfusion may lead to a trauma-related intestinal infarction.
Fig. 3. Small transverse mesocolon hematoma (arrow in a) from blunt trauma in a 61-year-old patient with thoracic injuries (b).
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Fig. 4. A 22-year-old man with blunt abdominal trauma, without any parenchymal organs lesion. The first MDCT examination showed evidence of free peritoneal fluid (arrows in a and b) without peritoneal free air (c). Twenty-four hours later the patient underwent a new MDCT examination for acute abdomen: pneumoperitoneum was noted (d), with free bubble gas close to an ileal segment in left abdomen (arrow in e), better evident on the coronal view (arrow in f). Note the appearance of the same loop of small intestine at the previous CT examination (segmented circle in b). Surgery confirmed the presence of ileal perforation.
3.4. Mesenteric stranding Mesenteric stranding is reported in literature as associated with mesenteric injury with or without bowel perforation [5]:
in fact, some investigators reported that mesenteric infiltration has been seen in 68% of patients with bowel injury, but also in 23% with other abdominal injuries [13]. However association of this finding with increased bowel wall thickness may be highly
S. Romano et al. / European Journal of Radiology 59 (2006) 359–366
suggestive for a major intestinal injury [5,18]. When the bowel shows no significant abnormalities but there is evidence of a mesenteric hematoma (Fig. 3), diagnosis of an isolated mesenteric vessel lesion should be suggested [5]. 3.5. Fluid in peritoneal/retroperitoneal recesses The evidence of free peritoneal fluid in absence of traumatic lesion to abdominal solid organs seems to be suggestive of bowel or mesenteric laceration [5], however in this case it is mandatory to evaluate the presence of other additional findings predictors of bowel injury, such as the abnormal bowel thickening or the pneumoperitoneum (Fig. 4). Free intra-peritoneal oral contrast presents high specificity for bowel perforation [5], whereas retroperitoneal peri-duodenal hematoma may be considered a specific sign of duodenal injury [5].
363
3.6. Parietal laceration and discontinuity Discontinuity of bowel wall may be difficult to note and diagnosis of intestinal laceration is essentially based on secondary findings [5]. However, because additional findings such as the distribution of the free air may be a clue to the site of an injured intestine [24], MDCT multi-planar reconstructions from isotropic data set may allow an optimal visualization of the intestinal wall in case of parietal laceration from blunt trauma (Figs. 5 and 6). 3.7. Free peritoneal/retroperitoneal air Free peritoneal or retroperitoneal air has a sensitivity of 44–55% [5,16,17] in indicating a bowel perforation, however
Fig. 5. A 23-year-old patient with pelvic fracture (arrow in a) from trauma and consequent burst injury of the caecum (b), with evidence of perivisceral hematoma and pneumoperitoneum (arrow in c).
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Fig. 6. In a 40-year-old patient with complex pelvic fracture (a), evidence of a right colon traumatic herniation (b) was noted. Conspicuous emphysema of the soft tissue was also present (c and d). A dislocated osseous fragment was appreciable in the region of intestinal herniation (d), better evident at coronal thick slab MIP reconstruction (e). Surgery confirmed the presence of right colon laceration (f): note the evidence of the small osseous interposed fragments already appreciated at MDCT images.
barotraumas and mechanical ventilation can results in air below the diaphragm [5,25]. Early detection of traumatic injury of the intestine is often not easy, but repeated examinations after several hours may reveal an increased amount of free air [5] (Fig. 4).
3.8. Extravasation of contrast medium Extravasation of endoluminal contrast and free peritoneal air have been reported to be usually seen in case of bowel rupture [13], whereas extravasation of mesenteric vascular contrast
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Fig. 7. A 25-year-old man with thoraco-abdominal trauma from car crash. No evidence of abdominal parenchymal organ injuries or peritoneal fluid at admission. Two days later, presence of bloody diarrhea. Patient underwent endoscopic examinations of the colon and stomach, but no source of hemorrhage was found. MDCT performed with i.v. contrast enhancement without administration of any endoluminal contrast, showed mucosal hyperdensity from hemorrhage of a jejunal loop (a), better evident at MPR (b) and MIP (c) coronal reconstructions, confirmed at surgery.
medium seems to be appreciable only in case of proven bowel or mesenteric injury (16%) [13]. In case of endoluminal hemorrhage, MDCT may be an useful tool to detect extravasation in the intestinal segment especially when conventional endoscopy cannot be used as diagnostic approach (Fig. 7). 4. Summary For the prospective CT diagnosis of bowel injury, CT had a reported sensitivity of 64%, an accuracy of 82% and a specificity of 97% [13]. Relevant predictors of bowel injury included mesenteric infiltration, bowel wall thickening, extravasation of vascular or enteric contrast agent and the presence free air [13]. In a retrospective blinded review of patients with bowel injury, CT
showed good to excellent inter-observer reliability for individual CT signs as well as for diagnosis of bowel and visceral injuries. However, it seems that experience plays a great role for a correct diagnosis: faculty radiologists tended to diagnose injuries with greater accuracy and confidence, but they showed significantly better performance than residents only in diagnosing duodenal perforation [13]. Moreover, performance was lower for faculty, senior radiologists and young residents in detection of stomach and colon injury and for the detection of hematoma of jejunum and ileum [13]. It can be hypothesized that it can occurs because either stomach and colon cannot follow the same wall semeiotics in damage from blunt trauma respect to the small bowel. However, no individual CT sign can be considered both sensitive and specific for bowel or mesenteric injuries [13]. In these cases, the key to afford the correct diagnosis should be also to consider the
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eventual presence of lesions to abdominal solid organs, in order to accurately detect the nearby territory, searching for additional injury to hollow viscera and mesentery. In conclusion, whereas helical CT scanning was very accurate in detecting bowel and mesenteric injuries, as well as in determining the need for surgical exploration in bowel injuries [7], the latest generation of CT with multi-detector row technology seems to be more sensitive and specific than other imaging techniques in detection of bowel and mesenteric injuries [12]. However, a correct diagnosis of intestinal damage from blunt abdominal trauma may be effected considering the presence of one or more signs from the entire spectrum of findings, correlating the imaging to the clinical evidence. References [1] Nghiem HV, Jeffrey Jr RB, Mindelzun RE. CT of blunt trauma to the bowel and mesentery. Semin Ultrasound CT MR 1995;16(2):82–90. [2] Soto JA. Abdominal trauma: hollow organs. In: Instructional Course Handouts, The American Roentgen Ray Society 105th Meeting, IC 409 B. 2005. p. 50–95. [3] Sharma OP, Oswanski MF, Singer D, Kenney B. The role of computed tomography in diagnosis of blunt intestinal and mesenteric trauma (BIMT). J Emerg Med 2004;27(1):55–67. [4] Menegaux F, Tresallet C, Gosgnach M, Nguyen-Thanh Q, Langeron O, Riou B. Diagnosis of bowel and mesenteric injuries in blunt abdominal trauma: a prospective study. Am J Emerg Med 2006;24(1):19–24. [5] Brody JM, Leighton DB, Murphy BL, et al. CT of blunt trauma bowel and mesenteric injury: typical findings and pitfalls in diagnosis. Radiographics 2000;20(6):1525–36. [6] Mirvis SE, Gens DR, Shanmuganathan K. Rupture of the bowel after blunt abdominal trauma: diagnosis with CT. Am J Roentgenol 1992;159(6):1217–21. [7] Killeen KL, Shanmuganathan K, Poletti PA, Cooper C, Mirvis SE. Helical computed tomography of bowel and mesenteric injuries. J Trauma 2001;51(1):26–36. [8] Motateanu M, Mirescu D, Schwieger AF, Laverriere C. Computed tomography of retroperitoneal duodenal rupture in blunt abdominal trauma. Eur J Radiol 1992;15(2):163–5. [9] Jacobs JE, Megibow AJ. CT of GI trauma. Crit Rev Comput Tomogr 2004;45(3):157–80.
[10] Scaglione M, de Lutio di Castelguidone E, Scialpi M, et al. Blunt trauma to the gastrointestinal tract and mesentery: is there a role for helical CT in the decision-making process? Eur J Radiol 2004;50(1):67–73. [11] Stuhlfaut JW, Soto JA, Lucey BC, et al. Blunt abdominal trauma: performance of CT without oral contrast material. Radiology 2004;233(3):689–94. [12] Hawkins AE, Mirvis SE. Evaluation of bowel and mesenteric injury: role of multidetector CT. Abdom Imaging 2003;28(4):505–14. [13] Butela ST, Federle MP, Chang PJ, et al. Performance of CT in detection of bowel injury. Am J Roentgenol 2001;176(1):129–35. [14] Brooks A, Bebington BD, Lucas S, Oettle GJ. Intussusception caused by blunt abdominal trauma. J Trauma 1999;47(1):156–7. [15] Sandrasegaran K, Kopecky KK, Rajesh A, Lappas J. Proximal small bowel intussusceptions in adults: CT appearance and clinical significance. Abdom Imaging 2004;29(6):653–7. [16] Levine CD, Gonzales RN, Wachsberg RH. CT findings in bowel and mesenteric injuries. J Comput Assist Tomogr 1997;21:974–9. [17] Breen DJ, Janzen DL, Zwirewich CV, et al. Blunt bowel and mesenteric injury: diagnostic performance of CT signs. J Comput Assist Tomogr 1997;21:706–12. [18] Dowe MF, Shanmuganathan K, Mirvis SE, et al. CT findings of mesenteric injury after blunt trauma: implications for surgical intervention. Am J Roentgenol 1997;168:425–8. [19] Crema MD, Arrive L, Monnier-Cholley L, Tubiana JM. Post-traumatic intramural hematoma of the colon. J Radiol 2004;85:2039–41. [20] Kocaoglu M, Ors F, Bulakbasi N, Ucoz T, Ates Y. Duodenal intramural hematoma due to blunt abdominal trauma. Ulus Travma Derg 2005;11(2):165–8. [21] Altay T. Chronic duodenal stenosis and periduodenal fibrosis secondary to a intramesenteric cyst arising from an old traumatic hematoma: a case report. Ulus Travma Derg 2005;11(2):162–4. [22] Mirvis SE, Shanmuganathan K, Erb R. Diffuse small-bowel ischemia in hypotensive adults after blunt trauma (shock bowel): CT findings and clinical significance. Am J Roentgenol 1994;163(6):1375–9. [23] Sivit CJ, Eichelberger MR, Taylor GA. CT in children with rupture of the bowel caused by blunt trauma: diagnostic efficacy and comparison with hypoperfusion complex. Am J Roentgenol 1994;163:1195–8. [24] Yama N, Kimura Y, Tatsumi H, et al. Nominal free air in the left inguinal fossa due to perforation of the sigmoid colon in a case of blunt abdominal trauma: CT diagnosis. Abdom Imaging 2006;31(1): 57–8. [25] Kane NM, Francio IR, Burney RE, et al. Traumatic pneumoperitoneum: implications of computer tomography diagnosis. Invest Radiol 1991;26:574–8.
MDCT in blunt intestinal trauma Stefania Romano a,∗ , Mariano Scaglione a , Giovanni Tortora a , Antonio Martino b , Francesco Di Pietto a , Luigia Romano a , Roberto Grassi c a
Department of Diagnostic Imaging, “A.Cardarelli” Hospital, 80131 Naples, Italy b Trauma Center, “A.Cardarelli” Hospital, 80131 Naples, Italy c Department “Magrassi-Lanzara”, Section of Radiology, Second University of Naples, 80138 Naples, Italy Received 21 May 2006; accepted 24 May 2006
Abstract Injuries to the small and large intestine from blunt trauma represent a defined clinical entity, often not easy to correctly diagnose in emergency but extremely important for the therapeutic assessment of patients. This article summarizes the MDCT spectrum of findings in intestinal blunt lesions, from functional disorders to hemorrhage and perforation. © 2006 Elsevier Ireland Ltd. All rights reserved. Keywords: Intestine; Trauma; MDCT; Abdomen; CT; Trauma
1. Introduction
2. MDCT technique
Intestinal mesenteric injuries are found in approximately 5% of all patients undergoing laparotomy after blunt abdominal trauma [1]. About 1.3% of patients with blunt abdominal trauma presents bowel injuries, that are frequently associated with abdominal solid organs lesions [2]. Mainly, there are three types of injuries: crush, shearing forces at fixed sites of attachment, burst injuries from increase in endoluminal pressure [2]. These lesions are related to a high morbidity and mortality, representing a diagnostic dilemma either from trauma surgeons and emergency physicians [3]. Actually, a non-operative management is often the treatment of choice for abdominal solid organs lesions from trauma [4], however because missed bowel and mesenteric injuries are possible [4], early diagnosis and treatment are critical to increased the survival rate [5]. Computed tomography (CT) has been initially proposed in the past two decades in the acute clinical setting of patients with abdominal blunt trauma suspected to have bowel and mesenteric lesions, becoming the primary modality for the imaging in these cases [5–9].
In the recent past years, helical CT was considered a sensitive tool in the identification of bowel and mesenteric injury after blunt trauma, providing a wide spectrum of findings [10]. Multidetector row CT (MDCT) examination without oral contrast material seems adequate for depiction of bowel and mesenteric injuries that require surgical repair [11]. Because of the improved image quality provided by the new generation of scanners, results are comparable with previously reported data for single-detector row helical CT with oral contrast material [11]. The acquisition of initial scans without oral contrast material seems to help to meet criteria of safety and efficiency without sacrificing diagnostic accuracy [11]. Pre-contrast abdomino-pelvis scans (5 mm slice thickness) are useful to better characterize the attenuation values of organs and structures in order to detect or rule out hemorrhagic phenomena and to evaluate any post-contrast HU abnormal changes. A biphasic study in arterial and venous phase is indicated especially when active bleeding or major vessels trauma are clinically suspected. In suspicion of low-flux vascular extravasation from minor vessels, a delayed phase may be added to the examination protocol. Acquisition parameters using an optimised ratio between slice thickness and reconstruction interval (i.e.: 3/3 mm acq., back recon. 1/1 mm), may allow a targeted multiplanar reconstruction in the post-processing elaboration.
∗
Corresponding author at: Via G.Fava 28 parco la piramide, 80016 Marano di Napoli, Italy. Tel.: +39 0817426089. E-mail address: [email protected] (S. Romano). 0720-048X/$ – see front matter © 2006 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ejrad.2006.05.011
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S. Romano et al. / European Journal of Radiology 59 (2006) 359–366
Fig. 1. In a middle aged patient with blunt torso trauma and thoracic injury (a), intestinal entero-enteric non-obstructive intussusception (b) was noted, not associated to parenchymal organs injury. Following MDCT control at 48th hour from trauma after administration of endoluminal contrast medium through naso-duodenal tube confirmed the finding (c). Resolution of the event was appreciable starting from 1 day later (d).
3. Spectrum of MDCT Findings Computed tomographic findings of bowel injury from blunt trauma include extraluminal free peritoneal or retroperitoneal air, visualization of direct tears in the bowel wall, intra-peritoneal or retroperitoneal free or collected fluid, bowel wall thickening, abnormal bowel wall enhancement, mesenteric infiltration or hematoma, extravasation of enteric or vascular contrast medium, ileus [12,13]. Bowel wall thickening as well as mesenteric infiltration and free intra-peritoneal air seem to be more relevant predictors of bowel injury [13].
3.1. Functional disorders Intestinal distension by fluid without evidence of an effective site of obstruction may be observed in patients with blunt abdominal trauma, although it can be related to intramural hematoma that in rare cases may cause an intussusception of the intestine [14], often as a non-occlusive and transient event (Figs. 1 and 2). Ileus is a less effective predictor of bowel injury from blunt trauma than other more sensitive and specific findings [13], however intussusception from functional disorders caused by trauma requires monitoring to exclude progression of the transient disease into a confirmed intestinal obstruction [15], preferably with abdominal plain film. MDCT-enteroclysis may be an additional useful follow-up technique to study a trauma-related small
intestine disease in the hemodynamically stable conservatively treated patient, to rule out an obstructive lesion, resulting in some cases resolutive for transient disorders (Fig. 1).
3.2. Bowel wall thickening Bowel wall thickening was seen in 60–75% of cases of bowel injury and in 8% of patients with other injuries [5,6,13] and it seems to be more sensitive for bowel injury than free peritoneal air or extravasation of oral contrast medium [5,6]. However, evaluation of this finding can be subjective, with wall thickness superior to 3–4 mm considered as abnormal [6,17,18], whereas most of contributions reported in literature seems not to consider the luminal distension. To assess a bowel wall abnormality in patients with blunt abdominal trauma, some authors suggested to consider the disproportionate thickening of the intestine compared to normal appearing tracts or a bowel wall thickness superior to 3 mm with adequate distension of the lumen [5]. Bowel wall thickening from intramural hematoma is a known evidence of blunt traumatic injury. Frequently only retrospectively diagnosed, it can be noted in all intestinal segments, although if the colon localization is rare, generally conservatively treated with spontaneous resolution [19]. The healing time of an intramural or a perivisceral hematoma may be various, in some cases with delayed complications: a duodenal intramural hematoma from blunt trauma resolved 48 days after trauma in a 14-year-old
S. Romano et al. / European Journal of Radiology 59 (2006) 359–366
361
Fig. 2. A 75-year-old patient with thoracic (a) and pelvic (b) lesions from blunt trauma. A colo-colic intussusception was appreciable (c). The transient event spontaneously recovered without symptoms or obstruction.
boy [20], whereas a case of intra-mesenteric traumatic cyst and fibrosis around the duodenum resulting in duodenal obstruction 8 years after injury [21]. 3.3. Abnormal wall enhancement The increased small bowel enhancement has been described as consequence of shock in trauma, in which the intestine is hypoperfused, with increased permeability and parietal thickening and hyperdensity as a consequence of interstitial leak of contrast medium [22]. Distension of the involved intestinal
segment is related to the accumulation of intraluminal fluid, presumably due to failed resorption capability [22]. It is important to note that these findings related to hypoperfusion cannot be noted in large bowel, suggestive of the lower oxygen demand or a less efficient shunting of blood away from this intestinal tract [22]. Evaluation parameters for wall enhancement may be the reference to the psoas muscle or that of adjacent vessels attenuation [23]. The isolated hyperdensity of the intestinal mucosa from blunt abdominal injury has been reported [5]. In presence of a major accident, the absence of reperfusion may lead to a trauma-related intestinal infarction.
Fig. 3. Small transverse mesocolon hematoma (arrow in a) from blunt trauma in a 61-year-old patient with thoracic injuries (b).
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Fig. 4. A 22-year-old man with blunt abdominal trauma, without any parenchymal organs lesion. The first MDCT examination showed evidence of free peritoneal fluid (arrows in a and b) without peritoneal free air (c). Twenty-four hours later the patient underwent a new MDCT examination for acute abdomen: pneumoperitoneum was noted (d), with free bubble gas close to an ileal segment in left abdomen (arrow in e), better evident on the coronal view (arrow in f). Note the appearance of the same loop of small intestine at the previous CT examination (segmented circle in b). Surgery confirmed the presence of ileal perforation.
3.4. Mesenteric stranding Mesenteric stranding is reported in literature as associated with mesenteric injury with or without bowel perforation [5]:
in fact, some investigators reported that mesenteric infiltration has been seen in 68% of patients with bowel injury, but also in 23% with other abdominal injuries [13]. However association of this finding with increased bowel wall thickness may be highly
S. Romano et al. / European Journal of Radiology 59 (2006) 359–366
suggestive for a major intestinal injury [5,18]. When the bowel shows no significant abnormalities but there is evidence of a mesenteric hematoma (Fig. 3), diagnosis of an isolated mesenteric vessel lesion should be suggested [5]. 3.5. Fluid in peritoneal/retroperitoneal recesses The evidence of free peritoneal fluid in absence of traumatic lesion to abdominal solid organs seems to be suggestive of bowel or mesenteric laceration [5], however in this case it is mandatory to evaluate the presence of other additional findings predictors of bowel injury, such as the abnormal bowel thickening or the pneumoperitoneum (Fig. 4). Free intra-peritoneal oral contrast presents high specificity for bowel perforation [5], whereas retroperitoneal peri-duodenal hematoma may be considered a specific sign of duodenal injury [5].
363
3.6. Parietal laceration and discontinuity Discontinuity of bowel wall may be difficult to note and diagnosis of intestinal laceration is essentially based on secondary findings [5]. However, because additional findings such as the distribution of the free air may be a clue to the site of an injured intestine [24], MDCT multi-planar reconstructions from isotropic data set may allow an optimal visualization of the intestinal wall in case of parietal laceration from blunt trauma (Figs. 5 and 6). 3.7. Free peritoneal/retroperitoneal air Free peritoneal or retroperitoneal air has a sensitivity of 44–55% [5,16,17] in indicating a bowel perforation, however
Fig. 5. A 23-year-old patient with pelvic fracture (arrow in a) from trauma and consequent burst injury of the caecum (b), with evidence of perivisceral hematoma and pneumoperitoneum (arrow in c).
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Fig. 6. In a 40-year-old patient with complex pelvic fracture (a), evidence of a right colon traumatic herniation (b) was noted. Conspicuous emphysema of the soft tissue was also present (c and d). A dislocated osseous fragment was appreciable in the region of intestinal herniation (d), better evident at coronal thick slab MIP reconstruction (e). Surgery confirmed the presence of right colon laceration (f): note the evidence of the small osseous interposed fragments already appreciated at MDCT images.
barotraumas and mechanical ventilation can results in air below the diaphragm [5,25]. Early detection of traumatic injury of the intestine is often not easy, but repeated examinations after several hours may reveal an increased amount of free air [5] (Fig. 4).
3.8. Extravasation of contrast medium Extravasation of endoluminal contrast and free peritoneal air have been reported to be usually seen in case of bowel rupture [13], whereas extravasation of mesenteric vascular contrast
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Fig. 7. A 25-year-old man with thoraco-abdominal trauma from car crash. No evidence of abdominal parenchymal organ injuries or peritoneal fluid at admission. Two days later, presence of bloody diarrhea. Patient underwent endoscopic examinations of the colon and stomach, but no source of hemorrhage was found. MDCT performed with i.v. contrast enhancement without administration of any endoluminal contrast, showed mucosal hyperdensity from hemorrhage of a jejunal loop (a), better evident at MPR (b) and MIP (c) coronal reconstructions, confirmed at surgery.
medium seems to be appreciable only in case of proven bowel or mesenteric injury (16%) [13]. In case of endoluminal hemorrhage, MDCT may be an useful tool to detect extravasation in the intestinal segment especially when conventional endoscopy cannot be used as diagnostic approach (Fig. 7). 4. Summary For the prospective CT diagnosis of bowel injury, CT had a reported sensitivity of 64%, an accuracy of 82% and a specificity of 97% [13]. Relevant predictors of bowel injury included mesenteric infiltration, bowel wall thickening, extravasation of vascular or enteric contrast agent and the presence free air [13]. In a retrospective blinded review of patients with bowel injury, CT
showed good to excellent inter-observer reliability for individual CT signs as well as for diagnosis of bowel and visceral injuries. However, it seems that experience plays a great role for a correct diagnosis: faculty radiologists tended to diagnose injuries with greater accuracy and confidence, but they showed significantly better performance than residents only in diagnosing duodenal perforation [13]. Moreover, performance was lower for faculty, senior radiologists and young residents in detection of stomach and colon injury and for the detection of hematoma of jejunum and ileum [13]. It can be hypothesized that it can occurs because either stomach and colon cannot follow the same wall semeiotics in damage from blunt trauma respect to the small bowel. However, no individual CT sign can be considered both sensitive and specific for bowel or mesenteric injuries [13]. In these cases, the key to afford the correct diagnosis should be also to consider the
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