Emerg Radiol (2013) 20:545–552 DOI 10.1007/s10140-013-1122-z
PICTORIAL ESSAY
CT findings in pediatric blunt intestinal injury Ruba Khasawneh & Raghu H. Ramakrishnaiah & Sumit Singh & Shilpa V. Hegde
Received: 6 February 2013 / Accepted: 19 March 2013 / Published online: 13 April 2013 # Am Soc Emergency Radiol 2013
Abstract Trauma is the leading cause of morbidity and mortality in children. Computed tomography examinations play an important role in the management of patients with major trauma. Though abdominal trauma is less common compared to head injuries, the associated morbidity and mortality are substantial. It is easier to diagnose solid abdominal injuries than intestinal or mesenteric injuries on CT examinations. However, recognition of bowel injury is very important as a delay in diagnosis increases the morbidity and mortality. Hence, with every CT of the abdomen and pelvis, the radiologist must look for signs of bowel and mesenteric injury. This pictorial review presents various CT findings of blunt intestinal injury in children. Keywords Pediatric . Intestinal injury . CT . Blunt abdominal trauma
Background Trauma is the leading cause of mortality and morbidity in children and adolescents [1]. Motor vehicle accidents and sports-related injuries are the most common causes of traumatic injuries in children [2]. Head and limb injuries are the most common injuries. Though abdominal and pelvic injuries account for only 10 % of all injuries, blunt intestinal injury is relatively common in children compared to adults [2, 3]. Many factors predispose the child to abdominal injury. The musculoskeletal system of the child is immature and hence does not provide adequate protection to the intraR. Khasawneh : R. H. Ramakrishnaiah : S. Singh : S. V. Hegde (*) Section of Pediatric Radiology, Department of Radiology, Arkansas Children’s Hospital, University of Arkansas for Medical Sciences, 1 Children’s way, Little Rock, AR 72202, USA e-mail:
[email protected]
abdominal organs. The intra-abdominal organs are relatively larger in relation to the size of the body. A smaller size also means that larger force is sustained per surface area. Children also have a less muscular abdominal wall and less intra-abdominal adipose tissue and connective tissue to provide adequate ‘cushioning’ to the organs. These factors make the child more vulnerable to blunt intra-abdominal injury [2]. In addition, the seat belt designed for an adult does not provide a tight fitting across a child’s pelvis [4]. A porcine animal model demonstrated that the mechanism of injury to an organ (solid organ or hollow viscous) is due to a direct compressive force from the seatbelt [1]. Clinical examination findings may be nonspecific and in the presence of neurological injury, less reliable in the diagnosis of blunt intestinal injury. Ultrasound examinations may only demonstrate free fluid and is less reliable. Computed tomography of the abdomen and pelvis with IV contrast is the investigation of choice for the evaluation of blunt intestinal injury.
Role of CT in the evaluation of blunt intestinal injury There are varied reports on the performance of CT in diagnosing intestinal injury with some studies showing CT being highly accurate and others depicting CT as a less useful tool. The degree of variation in the usefulness of CT might be related to various factors like the technique of CT examination, levels of expertise of the radiologists, and varying accuracies of the findings on CT in cases of blunt intestinal injury [5]. The diagnosis of intestinal injury is more difficult than the solid organ injury even with computed tomography examinations [3]. The overall sensitivity and specificity of CT in diagnosing blunt intestinal injuries has been reported between 87 to 95 % and 48 to 84 %, respectively [3]. In a study performed on 331 children, the most common finding on CT was
546
Emerg Radiol (2013) 20:545–552
presence of free fluid, followed by abnormal bowel wall thickening and free air. All patients with free air in this group had bowel perforation. No other CT finding had a specific operative correlation [3]. Small intestine is the most commonly involved hollow viscera followed by colon and stomach and proximal jejunum distal to the ligament of Treitz and the distal ileum proximal to the ileocecal valve are the most commonly involved segments of small intestine [6]. The various CT findings of intestinal trauma can be divided into bowel and mesenteric findings. The bowel findings are focal and diffuse bowel wall thickening, focal and diffuse increased bowel wall enhancement, absent contrast enhancement of the bowel wall, and bowel wall discontinuity. Mesenteric stranding, mesenteric hematoma, active contrast extravasation, mesenteric vascular beading, and abrupt termination of the mesenteric vessels are the mesenteric signs described in blunt intestinal injury. Free intraperitoneal air and focal bowel wall thickening have been described to be stronger indicators for surgical intervention, whereas free intraperitoneal fluid, mesenteric stranding and mesenteric hematoma are less specific
indicators for surgical repair [7]. Though extraluminal contrast leak is an indicator for surgery, CT examinations are performed increasingly without the use of oral contrast in the setting of trauma [8, 9]. Abnormal increased bowel wall enhancement could be related to bowel injury or could be a part of the hypoperfusion complex. However, complete lack of bowel wall enhancement is a more specific indicator of bowel ischemia or infarction [8]. In this pictorial review, we describe various CT findings of blunt intestinal injury in children and discuss the importance of these findings.
Fig. 1 a–c Pneumoperitoneum with diaphragmatic rupture in a 10year-old male who fell off a tractor that ran over him. Patient also had liver laceration. a Coronal reformatted CT images of the abdomen with IV contrast in soft tissue window shows the ruptured diaphragm (solid arrow) with herniation of the liver into the right hemithorax. Fat stranding is seen at the root of the mesentery (curved arrow). No abnormality of the bowel loops was seen. Free fluid in the pelvis (long arrows) secondary to liver laceration. b Axial CT images of the thorax
in lung window level demonstrating right sided pneumothorax (arrow head) and small subcutaneous emphysema along the right lateral chest wall (short arrow). c Axial CT images of the abdomen with IV contrast in soft tissue window showing the liver laceration (open arrow) and pneumoperitoneum (dashed arrow). Pneumoperitoneum was related to the diaphragmatic rupture as there was no evidence of bowel perforation. Surgical management consisted of repair of the diaphragm
1. Free intra-abdominal air: CT is very sensitive in detecting extraluminal air and free air that is too small to be detected by radiographs can be demonstrated on CT [10]. Presence of free intra-abdominal air in the setting of blunt abdominal injury may be attributed to bowel perforation and may lead to laparotomy. However, free intra-abdominal air can be encountered in the absence of intestinal perforation in patients with barotrauma, bladder injury with an indwelling foley catheter, and massive pneumothorax [6] (Fig. 1a–c).
Emerg Radiol (2013) 20:545–552
547
Free air between the abdominal wall and the parietal peritoneum can be seen in patients with rib fractures and pneumothorax. This is a potential diagnostic pitfall and is referred to as pseudopneumoperitoneum [6]. Pseudopneumoperitoneum is also seen in cases of chest tube insertion where air dissects between the fascial planes of the anterior abdominal wall. In these cases, the air is usually located within the inner layer of the anterior abdominal wall and found in the upper abdomen, close to the anterior or anterolateral abdominal wall [11]. In the absence of a bowel abnormality, other reasons should be sought as a cause of pneumoperitoneum. The presence of pneumoperitoneum should however lead to a careful search for any bowel abnormality (Fig. 2a–d). Finding of extraluminal air has a sensitivity of 30 to 60 % and specificity of 95 % for bowel injury and absence of free intra-abdominal air is not a good negative predictor of bowel injury as majority of patients with proven bowel perforation do not have free air on CT examinations [6]. 2. Free fluid/hemoperitoneum: Free fluid/hemoperitoneum is the most common CT finding in pediatric trauma [7, 8]. The sensitivity of CT in demonstrating free fluid is reported as 90 to 100 % with a specificity of however only
15 to 25 % [6]. Free fluid can be confined to one location or alternatively seen in multiple locations in the abdomen and pelvis. It is most commonly seen in the pelvis secondary to gravity and to the anatomy of the abdominal compartments [12]. Free fluid can vary in density according to its contents. Free fluid of higher attenuation values represents hemorrhage or extravasated enteric contrast [13]. Retroperitoneal free fluid is a more specific sign which can localize the site of injury as opposed to the intraperitoneal free fluid which is freely mobile and tends to accumulate in the dependent areas [13]. Small amount of free fluid can be physiological in females or could be related to vigorous resuscitation of hypovolemic shock in both sexes [12]. Isolated free fluid in the absence of solid organ injury or pelvic fracture is highly suggestive of bowel or mesenteric injury and is reported in higher frequency in the pediatric population compared to the adult population [12, 14] (Fig. 3a,b). It is also true that it is rare to have isolated free fluid in cases of bowel/mesenteric injury and usually other findings of bowel or mesenteric injury coexist [7, 8]. On the other hand lack of free fluid on CT has a high negative predictive value in the exclusion of significant bowel or mesenteric injury [13].
Fig. 2 a–d Pneumoperitoneum with gastric perforation in a 15-yearold male who sustained blunt abdominal injury while playing football. CT of the abdomen and pelvis was performed with IV and oral contrast at an outside institution before the referral. a Axial CT through the upper abdomen in soft tissue window demonstrates large amount of free intra-abdominal air (solid arrow) and evidence of bowel wall discontinuity (long arrow). b Axial CT in lung window at the same level shows the pneumoperitoneum with visualization of the falciform
ligament (solid arrow). c and d Images of the lower abdomen and pelvis in the same patient also show free fluid. High-density material (dashed arrows) was seen in the right paracolic gutter and gravitydependent pelvis secondary to spillage of gastric contents. Diffuse thickening of bowel loops (arrow heads in c) was likely related to hypovolemia or secondary inflammation as no other bowel abnormality was seen at surgery. Beading of mesenteric vessels (curved arrow in c) was also evident
548
Emerg Radiol (2013) 20:545–552
Fig. 4 Ileal injury in a 3-year-old male who was involved in a motor vehicle accident. Axial CT scan of the abdomen and pelvis with IV contrast shows bowel wall discontinuity of the ileum (arrow)
Thin section images and multiformatted images are helpful in detecting thin tears [13]. b. Abnormal bowel wall enhancement: Abnormal bowel wall enhancement is a subjective finding that varies with different CT techniques [7, 8]. It can be localized, diffuse, or patchy. The cause of increased enhancement is believed to be related to decreased perfusion and interstitial leak of contrast in the involved segment [7, 8]. Localized increased bowel wall enhancement indicates bowel injury with vascular involvement [7, 8]. The presence of patchy, irregular bowel enhancement suggests but is not diagnostic of full thickness bowel injury [8] (Fig. 5). The sensitivity and specificity of abnormal bowel wall enhancement has been reported as 10 to 15 % and 90 %, respectively [6]. Fig. 3 a–b 5-year-old female who was involved in a motor vehicle accident. CT scan of the abdomen and pelvis was performed with IV contrast only. a Axial slice of the pelvis shows moderate amount of free fluid in the pelvis (long arrow). There was no evidence of solid organ injury or pelvic fracture to explain the free fluid. b Careful evaluation of the bowel demonstrated complete absence of mucosal enhancement in a few pelvic ileal loops and in the sigmoid (solid arrow). At surgery 2-ft dead ileum and a segment of devitalized sigmoid colon was found. Note the normal proximal bowel enhancement (curved arrow). Some free fluid also seen adjacent to the liver (long arrow)
3. Bowel findings a. Bowel wall discontinuity: (Fig. 4) Discontinuity of bowel wall has been defined as a low attenuation cleft that runs perpendicular to the bowel wall on a CT examination performed with IV contrast [15]. This is an uncommon finding as smaller tears are evident only at surgery. However, this sign if seen is highly specific and diagnostic of bowel injury necessitating surgical repair. The sensitivity and specificity of this finding is reported as 5 to 10 % and 100 %, respectively [6, 8].
Fig. 5 Transection at the duodenojejunal junction in a 16-month-old female who sustained blunt abdominal injury. Axial CT of the abdomen and pelvis with IV contrast. Note the site of transection (long arrow) and the irregular enhancement of the bowel wall. Solid arrow refers to a dilated segment of the colon
Emerg Radiol (2013) 20:545–552
549
Fig. 8 Duodenal hematoma in an 11-year-old male with handlebar injury. Axial CT of the abdomen and pelvis with IV contrast showing the duodenal hematoma (arrow). The patient was managed conservatively Fig. 6 Shock bowel in a 21-month-old male with blunt abdominal injury. Coronal reformatted CT scan of the abdomen and pelvis with IV contrast. Note the large amount of free fluid in the abdomen and pelvis and the diffusely hyperenhancing bowel wall
Diffuse increased bowel wall enhancement is part of the hypoperfusion complex or ‘shock bowel’ and is less specific [7, 8] (Fig. 6). c. Lack of bowel wall enhancement: Absent bowel enhancement is an important and perhaps specific finding that indicates ischemia or infarction of the non-enhancing bowel segment [8] (Fig. 7a,b). This finding is more obvious when the bowels are well distended and fluid filled. Abrupt change in the pattern of bowel enhancement is an important clue for the diagnosis. This finding usually exists with other CT findings of bowel injury [13]. Fig. 7 a and b Same patient as in Fig. 3. Five-year-old female who was involved in a motor vehicle accident. CT scan of the abdomen and pelvis was performed with IV contrast only. Coronal reformatted image (a) shows the abrupt transition to complete lack of enhancement of some segments of ileum. The patient also has mesenteric stranding (arrow in b) and free fluid. Two-feet dead ileum and a segment of devitalized sigmoid colon were found at surgery
d. Bowel wall thickening: The sensitivity and specificity of focal bowel wall thickening has been reported between 55 to 75 % and 90 %, respectively [6]. The bowel wall is considered thickened if it appears disproportionately thicker in comparison to other bowel segments or if the bowel wall is circumferentially thickened and measures more than 3–4 mm in thickness. The pathophysiology of bowel wall thickening in the setting of trauma could be related to vascular compromise and inflammation secondary to spillage of bowel contents [7, 8]. Bowel wall thickening may also be related to intramural hematoma which commonly occurs in the duodenum in the pediatric age group [6, 7] (Fig. 8). Bowel wall thickening can be localized or generalized. Localized isolated bowel wall thickening indicates serious bowel injury at that site that necessitates surgical repair [6–8] (Fig. 9).
550
Emerg Radiol (2013) 20:545–552
4. Mesenteric signs
Fig. 9 Jejunal injury in a 6-year-old female who was involved in a motor vehicle accident. CT of the abdomen and pelvis with IV contrast shows focal thickening of the jejunum and patchy abnormal enhancement of the bowel mucosa at the same site (long arrow). Bowel was viable at surgery and was repaired with sutures. Note the associated mesenteric vascular beading (curved arrow) and the mesenteric hematoma (short solid arrow)
a. Active extravasation: (Fig. 11a,b). Active mesenteric extravasation is 100 % specific for significant mesenteric injury and merits urgent surgical exploration [8]. However, this is a relatively rare finding and has been reported in approximately 17 % of bowel and mesenteric injuries [13]. The demonstration of this finding also depends upon the technique of acquisition of CT images and needs a higher rate of contrast administration to obtain adequate opacification of the mesenteric vessels [13]. b. Mesenteric vascular beading and abrupt termination of vessels: Mesenteric vascular beading is defined as irregular mesenteric vessels on CT and is found more often than active extravasation [8] (Figs. 2c and 9). Mesenteric vascular beading was seen in 39 % and abrupt termination of mesenteric vessels was seen in 35 % of patients with bowel and/or mesenteric injuries [13]. A combination of these two signs provided a better sensitivity and specificity and was seen
Diffuse bowel thickening is a less specific finding that could be part of the hypoperfusion complex or alternatively secondary to generalized peritonitis resulting from traumatic bowel injury if the scans are obtained at a delayed time [7] (Fig. 10). The specificity of bowel wall thickening increases if it is accompanied with pockets of inter-loop fluid or free intra-abdominal air [6, 8].
Fig. 10 Fifteen-year-old female who had sustained grade II liver and splenic injuries following a road traffic accident. Axial CT images of the abdomen and pelvis with IV contrast demonstrates diffuse thickening of the jejunum (long arrow) as a part of the hypoperfusion complex. Mesenteric hematomas were seen between the bowel loops (open arrow). The patient was managed conservatively as no focal bowel abnormality was seen. Also seen is free fluid in the right paracolic gutter (short arrow) secondary to solid organ injury and a right-sided surgical emphysema (arrow head)
Fig. 11 a–b Active hemorrhage (a) and pseudo aneurysm (b) formation in a 13-year-old male with history of road traffic accident. The patient underwent bowel resection
Emerg Radiol (2013) 20:545–552
551
c. Mesenteric hematoma/stranding: Mesenteric stranding is seen as an area of increased attenuation in the mesentery on CT [13]. Mesenteric stranding is a common finding which however is not specific (Figs. 1a and 7b). The reported sensitivity of mesenteric stranding is 69 %. Mesenteric hematoma on the other hand is a well-defined mass on the CT scan with sensitivity of 45–54 % (Fig. 12). These signs may be associated with bowel wall thickening due to ischemia from interruption of blood supply to the bowel [13]. In the absence of other signs of bowel or mesenteric injury, isolated mesenteric stranding/hematoma can be managed conservatively [13].
Conclusion
Fig. 12 Same patient as in Fig. 10. Coronal reformatted images of the abdomen and pelvis with IV contrast demonstrates multiple mesenteric hematomas between bowel loops (open arrows). The patient was managed conservatively
in 60 % of patients with surgically important mesenteric injury [13].
Imaging finding Free intraabdominal air
Sensitivity Specificity (%) (%) 30 to 6 95
Free fluid/ 90 to 100 hemoperitoneum Bowel wall discontinuity Increased bowel wall enhancement
Absent bowel wall enhancement
5 to 10 10 to 15
Not known
15 to 25
Solid organ injury is easily identified on CT examinations following blunt trauma. However, bowel or mesenteric injury can be more subtle and careful evaluation is required in all cases of trauma. It is also true that solid organ injuries are more often managed conservatively in children whereas significant bowel injury may require surgery. The above described signs usually exist in varying combinations and have a stronger association with bowel injury. For example free fluid in association with abnormal bowel enhancement or thickening is a better indicator of bowel/mesenteric injury than the presence of free fluid alone. It is important for the radiologists to identify these findings and systematically review the abnormalities to prevent unnecessary delays in patient management.
Pearls
Pitfall
Presence of pneumoperitoneum should lead to a careful systematic search for bowel injury
Free intra-abdominal air can be seen in the absence of intestinal perforation in patients with barotrauma, and massive pneumothorax Small amount of free fluid could be normal physiological finding in females
Presence of free fluid in the absence of solid organ injury or pelvic fracture suggests bowel or mesenteric injury 100 This sign if seen is highly specific and necessitates surgical repair 90 Localized increased bowel wall enhancement indicates bowel injury with vascular involvement and is believed to be related to decreased perfusion and interstitial leak of contrast High Perhaps this is a specific finding that indicates specificity ischemia or infarction of the non-enhancing bowel segment
This sign has low sensitivity and smaller tears are evident only at surgery Diffuse increased bowel wall enhancement is part of the hypoperfusion complex or “shock bowel” This sign has a low sensitivity as the enhancement of bowel wall depends on the contrast phase in which the scan was acquired
552 Localized bowel wall thickening
Emerg Radiol (2013) 20:545–552 55 to 75
90
Localized isolated bowel wall thickening indicates serious bowel injury at that site that necessitates surgical repair Active mesenteric extravasation is highly specific for significant mesenteric injury and merits surgical exploration Described as irregular mesenteric vessels and is seen more often than active extravasation
Active mesenteric 17 extravasation
100
Mesenteric 39 vascular beading
Not known
Abrupt termination of vessels Mesenteric hematoma Mesenteric stranding
35
Not known
High specificity
45–54
Not known
69
Not known
Isolated hematoma can be managed conservatively Seen as area of diffuse increased attenuation on CT
Conflict of Interest The authors declare that they have no conflict of interest.
References 1. Schonfeld D, Lee LK (2012) Blunt abdominal trauma in children. Curr Opin Pediatr 24(3):314–318 2. Gaines BA, Ford HR (2002) Abdominal and pelvic trauma in children. Crit Care Med 30(11 Suppl):S416–S423 3. Chatoorgoon K, Brown RL, Garcia VF, Falcone RA Jr (2012) Role of computed tomography and clinical findings in pediatric blunt intestinal injury: a multicenter study. Pediatr emerg care 28(12):1338–1342 4. Davies KL (2004) Buckled-up children: understanding the mechanism, injuries, management, and prevention of seat belt related injuries. J trauma nursing: the official J Soc Trauma Nurses 11(1):16–24 5. Butela ST, Federle MP, Chang PJ et al (2001) Performance of CT in detection of bowel injury. AJR Am J Roentgenol 176(1):129– 135 6. Soto JA, Anderson SW (2012) Multidetector CT of blunt abdominal trauma. Radiology 265(3):678–693 7. Strouse PJ, Close BJ, Marshall KW, Cywes R (1999) CT of bowel and mesenteric trauma in children. Radiographics: a review publication of the Radiol Soc of North America Inc 19(5):1237–1250
Diffuse bowel thickening is a less specific finding that could be part of the hypoperfusion complex This is a rare finding and depends on the technique of CT acquisition Demonstration of this sign depends on presence of contrast opacification of the vessels Difficult to differentiate from normal tapering especially in the distal vessels Other signs of mesenteric injury should be evaluated for Common finding that lacks specificity
8. Brofman N, Atri M, Hanson JM, Grinblat L, Chughtai T, Brenneman F (2006) Evaluation of bowel and mesenteric blunt trauma with multidetector CT. Radiographics: a review publication of the Radiol Soc of North America Inc 26(4):1119–1131 9. Holmes JF, Offerman SR, Chang CH et al (2004) Performance of helical computed tomography without oral contrast for the detection of gastrointestinal injuries. Ann Emerg Med 43(1):120–128 10. Furukawa A, Sakoda M, Yamasaki M et al (2005) Gastrointestinal tract perforation: CT diagnosis of presence, site, and cause. Abdom Imaging 30(5):524–534 11. Hamilton P, Rizoli S, McLellan B, Murphy J (1995) Significance of intra-abdominal extraluminal air detected by CT scan in blunt abdominal trauma. The Journal of trauma 39(2):331–333 12. Christiano JG, Tummers M, Kennedy A (2009) Clinical significance of isolated intraperitoneal fluid on computed tomography in pediatric blunt abdominal trauma. J Pediatr Surg 44(6):1242–1248 13. Hassan R, Abd Aziz A, Mohamed SK (2012) Computed tomography (CT) of bowel and mesenteric injury in blunt abdominal trauma: a pictorial essay. The Med J Malaysia 67(4):445–451, quiz 52 14. Sivit CJ, Taylor GA, Bulas DI, Bowman LM, Eichelberger MR (1991) Blunt trauma in children: significance of peritoneal fluid. Radiology 178(1):185–188 15. Kim SH, Shin SS, Jeong YY, Heo SH, Kim JW, Kang HK (2009) Gastrointestinal tract perforation: MDCT findings according to the perforation sites. Korean J Radiol: off J Korean Radiol Soc 10(1):63–70
