Abdominal

Computed Tomography in Blunt Trauma

By Stuart E. Mirvis and Kathirkamanathan

INCE THE EARLY 1980s computed tomography (CT) has come to play a greater S role in the initial evaluation of patients sustaining blunt or penetrating trauma. CT has largely replaced abdominal radiography, nuclear scintigraphy, intravenous pyelography (IVP), and sonography in the acute evaluation of the abdomen. Numerous publications have addressed the relative strengths and weaknesses of CT scanning of the abdomen versus the more traditional diagnostic peritoneal lavage (DPL). CT is advantageous over DPL in that (1) CT can assessthe retroperitoneum, (2) CT decreases the rate of nontherapeutic laparotomies, which varies from 6% to 25%, that are performed based on a positive DPL result,1-3(3) CT is more specific regarding the precise site and extent of injury, (4) CT can identify retroperitoneal or pelvic sources of hemorrhage that may create a false-positive DPL, (5) CT is noninvasive, (6) CT can detect intraparenchymal injury or subcapsular hemorrhage that may be missed by DPL, and (7) CT can be used serially to assess resolution or progression of injuries including those managed either expectantly or surgically. Critics of abdominal CT scanning point out a lack of sensitivity for detection of certain injuries particularly the bowel (occuring in up to 4% of major abdominal trauma) and pancreas.4J CT and DPL provide different and complimentary types of information and are not mutually

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exclusive studies.216-9 For instance, in some circumstances, CT may clarify an indeterminant DPL result or assessthe true extent of injury in an alert, hemodynamically stable patient without significant positive physical findings but with a positive DPL result. In the University of Maryland Medical Center, both DPL and CT are used as shown in Table 1. TECHNICAL

Obviously, the diagnostic accuracy of CT scanning for abdominal trauma depends on the Table 1. Use of Diagnostic Peritoneal Lavage and Contrast-Enhanced Computed Tomography in Abdominal Trauma DPL

CECT

Hemodynamically unstable (if time) Requires immediate nonabdominal surgery Uncertain CTfindings CT unavailable or poor quality Lack of expert CT interpretation Negative CT with persistent or increasing abdominal pain Inability in administer IV contrast due to major allergy Uncooperative patient who can not be sedated

Hemodynamically stable Alert patient with minimal abdominal pain Unconscious/unreliable examination* Indeterminant or unsuccessful DPL Surgical contraindication to DPL Cell count positive DPLt Major flank impact with no/minimal abdominal findings Penetrating flank impact+ Assessment of pelvic hemorrhage as major source of blood loss9 Decrease in hematocrit of uncertain etiology Persistent abdominal pain with negative DPL/I

ABBREVIATIONS CECT, contract enhanced computed tomography; CT, computed tomography; DPL, diagnostic peritoneal lavage; EPB, extraperitoneal bladder; ERCP, endoscopic retrograde cholangiopancreatography; IPB, intraperitoneal bladder: IVP, intravenous pyelography

From the Department of Radiology, University of Ma yland Medical Center, and the Maryland Institute for Emergency Medical Services Systems, Baltimore, MD. Address reprint requests to Stuart E. Mink, MD, Depatiment of Radiology, lJniversi& of Ma yland Medical Center, 22 S Greene St, Baltimore, MD 21201. Copyright 0 1992 by W.B. Saunders Company 0037-198X/92/2703-0004$5.00/0 150

CONSIDERATIONS

*Controversial as to which modality is better. DPL is preferred at the Shock-Trauma Center due to concern over bowel injury. Eiomewhat controversial. In a hemodynamically stable alert patient, CT can assess the source and quantity of hemorrhage and in the majority of patients avoid nontherapeutic laparotomy. *Requires use of colonic opacification to assess extent of injury. §The presence of pelvic fracture should prompt CT if the patient is hemodynamically stable to assess the solid viscera and intraperitoneal blood. If the major source of hemorrhage is retroperitoneal and no solid visceral injury is identified, celiotomy (which may precipitate expansion of retroperitoneal hemorrhage) may be delayed in favor of external fixation and, if needed, angiography with possible embolization. JICT can detect retroperitoneal injuries or contained solid visceral injuries not detected by DPL. Reprinted with permission.84

Seminars

in Roentgenology,

Vol XXVII, No 3 (July),

1992:

pp 150-183

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quality of the scan as well the experience and expertise of the interpreter. To maximize image quality several conditions should be met including (1) rapid scan time (2 seconds or less) to decrease motion, (2) removal of extraneous lines and tubes from the scan field to reduce artifacts, (3) brief interscan delay to decrease overall examination time, (4) maximizing patient cooperation to decrease motion, (5) excellent intravenous contrast enhancement, preferably by power injector, to optimally enhance the liver and spleen (inject 80 mL of 60% contrast at 2 mL/s for 40 seconds followed by another 70 mL of 60% contrast at 0.5 mL/s). At the Shock-Trauma Center, intravenous enhancement is always used unless contraindicated by known major contrast allergy or major renal insufficiency, (6) scanning of the abdomen and pelvis to detect hemoperitoneum and retroperitoneal pelvic hematoma, and (7) use of optimal CT scan parameters including kilovolt, milliampere detector calibration, field-of-view selection, patient positioning, etc. At the ShockTrauma Center, oral contrast is routinely administered (360 mL dilute Hypaque [Winthrop Pharmaceuticals, New York, NY], 5.0 g in 12 ounces) 30 minutes before scanning, whenever possible, and another 120 to 180 mL just before initiation of scanning. In urgent situations the contrast can be administered immediately before scanning to at least opacify the

Fig 1. Bowel perforation secondary to penetrating trauma. CT scan of an apparently superficial self-inflicted shotgun wound to the left flank of a 32-year-old mental patient showed extravasation of contrast and gas from the colon (arrows). At surgery, the patient had a perforation of the splenic flexure of the colon. (Reprinted with permission.*4)

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stomach and duodenum. Oral contrast has proven very useful in detecting bowel injuries, in distinguishing bowel from mesenteric hematoma, and in delineating the anatomy of the pancreas. Pulmonary aspiration of oral contrast has not been a problem, but if desired, oral contrast may be aspirated from the stomach through nasogastric tube after the CT study. Rectal contrast is not routinely used, but 500 to 1,000 mL of the above Hypaque solution is administered per rectum to evaluate the integrity of the colon in patients sustaining penetrating flank or back injury (Fig 1). SPECIFIC INJURIES

Hemoperitoneum

CT can detect very small quantities of blood in the abdominal cavity.‘” Localization to gravitydependent positions such as the pelvis, Morison’s pouch, paracolic gutters, and paravesicai spacesmakes inspection of these areas imperative (Figs 2 and 3). Intravenous and oral contrast also aid in the detection of hemoperitoneum. Acute hemorrhage appears as free fluid with CT density of 35 to 45 Hounsfield units (HU) but can achieve a density of 70 to 90 HU with clot formation. Excellent enhancement of the liver and spleen is important to detect adjacent clotted blood (Fig 4). Introduction of peritoneal lavage fluid or leakage of bile, small

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Fig 2. Sentinel clot sign. CT image shows both perisplenic (arrowheads) and perihepatic (arrows) hemorrhage. The blood adjacent to the spleen is of higher attenuation than that around the liver and in Morison’s pouch. This indicates that the site of origin of the bleeding is most likely the spleen. No definite injuries were identified in either organ on the study.

intestine thyme, or urine (opacified or unopacified) into the peritoneal cavity will impair the ability of CT to diagnose or quantify hemoperitoneum. CT detects the quantity of blood present within the peritoneal cavity but does not necessary reflect active hemorrhage. Brisk hemorrhage can occasionally be seen by CT as pools of

Fig 3. CT scan through the pelvis reveals extensive free intraperitoneal blood. A “hematocrit” effect is seen (arrows) as heavier intact red blood cells fell to the dependent aspect of the peritoneal cavity. The enhanced uterus (U) is easily distinguished from the surrounding hemorrhage. (Reprinted with permissi0n.w)

extravasated contrast-enhanced blood (Figs 5 and 6).” Usually, if multiple sites of hemoperitoneum are observed, the blood with the highest CT density lies in close proximity to the site of origin, the “sentinel clot” sign (Fig 2).‘* Hemoperitoneum should resolve significantly by 1 week after injury. Persistence of intraperitoneal

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Fig 4. Perisplenic hematoma. Enhanced CT scan of a 33-yearold woman injured in a motor vehicle accident reveals a large amount of partially clotted perisplenic blood displacing the spleen medially (arrows). There is minimal perihepatic intraperitoneal hemorrhage. On more caudal images (not shown), there was moderate left perinephric hemorrhage. The upper pole of the left kidney is nonperfused (open arrow). (Reprinted wtih permission.@)

blood without change for 3 to 7 days after injury suggestsongoing b1eeding.r” The spleen is the most commonly injured organ from blunt trauma’j and was diagnosed in 140 (3.4%,) of 4,120 patients admitted to the Shock-Trauma Center with blunt abdominal trauma during a 2-year period. Left lower rib fractures were seen in 26 (20%) patients with

splenic injuries. Injury may appear as contusion (irregular low or mixed attenuation), intraparenchymal laceration, high attenuation hematoma. subcapsular hemorrhage, or vascular pedicle injury (Figs 5, 7 through 9). Again. excellent intravenous contrast enhancement improves CT detection of splenic injury which is at least 98%~ sensitive when performed with optimal CT technique.” Motion, volume averaging, splenic lobulation, poor contrast opacification, adjacent

Fig 5. Major splenic disruption and active bleeding. This contrast enhanced CT image was acquired 12 hours after exploratory laparotomy for a positive peritoneal lavage in a 50-yearold man. At surgery, a minor splenic laceration was observed on the surface of the spleen and argon beam coagulated. Due to excessive postsurgical blood requirements, a CT scan was performed which showed a severely fragmented spleen with extravasation of contrast (blood) near the hilar region indicating active arterial bleading (arrows). Lower density free blood surrounds the enhanced liver. (Reprinted with permission.84)

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Fig 6. Gross renal hemorrhage. (A) This CT image of a 30-year-old woman who jumped from a 14th-floor window shows active hemorrhage anterior to the right kidney with extensive contrast pooling in the anterior and posterior pararenal space. The kidney (lower pole) appears grossly intact. (B) A flush abdominal aortagram shows marked spasm of the renal arteries and gross bleeding from a proximal mid-renal arterial branch (arrows). Gelfoam and steel coils stopped the hemorrhage, with sacrifice of renal perfusion, but the patient died 16 hours later from irreversible coagulopathy and extensive pelvic injury. (Reprinted with permission.“)

unopacified bowel, and early “bolus effect” can all mimic splenic injury (Figs 10 and 11). In general, isolated minimal splenic injuries or contusions will resolve with medical manage-

ment; however, no grading classification for splenic injury can, in every patient, reliably predict the outcome of a given injury.16 On occasion, splenic injuries that initially appear

Fig 7. Major splenic laceration and hematoma. (A) CT image of a 27-year-old man injured in a motor-vehicle accident reveals severe splenic lacerations with intrasplenic and perisplenic hemorrhage. Perihepatic hemoperitoneum is observed. (Reprinted with permission.“)

.

Fig 9. Regional splenic nonperfusion after trauma. Well-enhanced CT scan shows a sharply demarcated region of low attenuation in the posterior spleen compatible with nonperfusion. A faint vascular structure is observed in the posterior spleen that suggests markedly delayed perfusion to this area.

Fig 8. Gross splenic rupture. CT scan shows a fragmented spleen with surrounding hemorrhage. Note the marked medial displacement of the stomach. Perfhepatic hemoperltoneum is noted. This patient required splenectomy.

Fig IO. “Early contrast bolus effect” simulating splenic contusion. (A) This CT image was acquired immediately after contrast injection by power injector shows an inhomogeneous parenchymal enhancement pattern suggestive of parenchymal contusion. The image obtained immediately caudal to this section showed no evidence of injury. (B) A repeat delayed scan through the same sectfon reveals a homogeneous enhancement pattern. Such nonuniform parenchymal enhancement may be seen if images are acquired in the arterial phase of the contrast bolus.

Fig 11. Cleft simulating fractured spleen. CT scan was performed after a diagnostic peritoneal lavage. There is a linear low attenuation region across the anterior spleen (arrow) with surrounding fluid of intermediate density (20 HU). A presumptive diagnosis was made of splenic laceration. Exploration showed only a splenic cleft in the anterior superior spleen and serosanguinous ascites. No splenic injury was found. (Reprinted with permission.“)

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Fig 12. Postsplenectomy hemorrhage. CT scan acquired postsplenectomy caused by a falling hematocrit shows a high density area in the splenic fossa that has a splenic configuration. This represents a postspienectomy hematoma that resolved on subsequent scans. (Reprinted with permission.@)

minor by CT may develop major delayed hemorrhage.lh Usually, patients with minimal isolated splenic injury and little or no hemoperitoneum who are alert and do not require prolonged surgery for facial or orthopedic injuries during which abdominal physical findings can not be followed are ideal candidates for nonoperative management. Such patients should be followed-up with frequent physical examination,

serial hematocrit determination, and repeat abdominal CT scan at 48 to 72 hours and again at 10 days after injury. CT can reliably demonstrate healing or progression of splenic injuries managed nonoperatively or by splenorrhaphy. If the patient remains asymptomatic, CT is repeated at 4 to 6 weeks after injury before resumption of usual physical activity. Complications following splenectomy such as hemor-

Fig 13. Site of hepatic injury preoperatively. CT image acquired in a young girl struck by a motor vehicle shows a wide laceration between the right and left lobes (arrows) and extensive gross hemoperitoneum. The CT scan indicated the need for a left lobe lobectomy, which was successfully performed. (Reprinted with permission.“)

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Fig 14. Deep (periportal) hepatic laceration. CT scan shows several areas of irregular low density around the portal region that are believed to represent deep contusions (arrowheads). Also, a medial splenic laceration (open arrow) and perisplenic hemorrhage are seen. This patient was successfully managed without surgery.

rhage into the splenectomy bed (Fig 12) or abscess formation are easily diagnosed by CT (see below). Hepa tic Injury

The liver is the most frequently injured abdominal organ when both blunt and penetrating trauma are considered.17-20CT can detect a variety of injuries including contusion, laceration, biliary system injury, intraparenchymal and subcapsular hematoma, and interruption of vascular supply (Figs 13 through 17). The right lobe is most frequently injured due to its large volume and concurrent injury to the lower

Fig 15. Hepatic laceration and subcapsular hematoma. CT image of a 45-year-old man acquired 2 weeks after a motorvehicle accident for a sepsis work-up showed an unexpected peripheral right lobe liver laceration and subcapsular hematoma. The spleen had been previously removed. (Reprinted with permission.B4)

thorax is seen in 40% to 50% of patients.21-23 CT can also detect active intraparenchymal hemorrhage (Fig 17). CT has been most effective at decreasing the laparotomy rate for liver hemorrhage, which is not active in at least 50% to 70% of cases at the time of surgery.24-27 CT detects progression or resolution of injuries. “Delayed” progression of initial stable liver injury occurs (Fig 18) but is distinctly unusual without coagulopathy. Periportal low attenuation can be seen after hepatic trauma from periportal blood tracking (Fig 19) or from lymphedema due to tension pneumothorax, pericardial tamponade, congestive heart failure, acute vascular volume

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Fig 16. Deep complex hepatic laceratia 111s.This CT image shows multiple deep lacerations of the right lob le. The patient was nonoperativ ely managed.

overload, or hematoma obstructing the draining hepatic veins.‘3.‘8-3”Initially, liver injuries may enlarge as they resolve as a result of osmotic effects, the edges of lacerations become smoother, and clot density decreases (Fig 20). In patients with suspected biliary tree injury, cholescintigraphy is recommended for screening purposes, followed by, in positive cases, endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous cholangiography to provide details of anatomy. Bilomas may develop as a consequence of liver trauma and appear as low-attenuation rounded collections. Sonography may be valuable in distinguishing

the echo-free biloma from abscessesor hematomas that typically contain internal echoes.“’ Usually, bilomas are successfully managed nonoperatively but can be percutaneously evacuated if infected (see below). Pancreatic Injury

Pancreatic injury occurs in from 0.2% to 12% of patients sustaining abdominal injury.3’-3” Isolated pancreatic injury from blunt trauma is uncommon and usually the diagnosis of pancreatic injury is made at laparotomy for treatment of other injuries. The CT diagnosis of pancreatic injury is difficult, particularly in patients

Fig 17. Active hepatic artery bleeding. This CT scan obtained after surgery on a 19-year-old man involved in a motor-vehicle accident shows evidence of highcontrast material (HU > 140) consistent with extravasating contrast (arrowheads). Drains were present in the lateral aspect of the right upper abdomen. There is extensive destruction of the right hepatic lobe. Despite successful embolization of the right hepatic artery, the patient died of irreversiblecoagulopethy. (Reprinted with permission.“)

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Fig 18. Delayed extension of hepatic injury. (A) Admission CT scan of young man involved in a motor vehicle accident shows a small area of decreased density in the posterior right lobe of the liver believed to represent a contusion. (B) Four days after admission, the patient complained of right upper quandrant pain and this repeat scan shows extensive progression of injury with a large subcapsular hemorrhage and maceration of the lateral right hepatic lobe. Despite progression of injury, the patient remained clinically stable and was managed without surgery. (Reprinted with permission.“)

Fig 19. Periportal tracking of blood after liver trauma. CT scan of young woman involved in motor vehicle accident shows several small lacerations of the right anterior liver. Periportal low attenuation areas surrounding the portal veins centrally. This finding has been attributed to tracking of blood along the portal veins but may actually represent lymphatic distention. (Reprinted with permission.“)

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Fig 20. Resolution of hepatic contusion by CT. (A) Admission CT scan of a young man who sustained blunt trauma shows an area of decreased attenuation (contusion) in the posterior medial right lobe of the liver. The patient was observed without intervention. (B) This repeat CT image obtained 2 weeks later shows expansion of the area of injury, but decreased attenuation and a smoother interface with the adjacent liver. This pattern is typical of resolving liver injuries.

lacking retroperitoneal fat, and subtle pancreatic injuries can easily be overlooked particularly soon after trauma. Optima1 intravenous and oral contrast enhancement coupled with a high index of suspicion (seat-belt injury) improves sensitivity. Often initial evidence of pancreatic injury is both clinically absent and occult to CT detection. More than several hours after trauma, several CT findings may develop including (1) focal or diffuse pancreatic swelling, (2) linear lucency representing laceration (Figs 21 and 22), (3) thickening or fluid tracking along anterior Gerota’s fascia, (4) diffuse edema of the transverse mesocolon and peripancreatic fat

(Fig 23), (5) fluid collections in the anterior pararenal space, and (6) overt or subtle intrapancreatic or peripancreatic hemorrhage (Fig 24).“4-.19As the time from initial trauma progresses, edema, inflammation, and autodigestion increase the CT signs suggesting pancreatic injury.38 CT findings that may mimic or falsely suggest pancreatic injury include unopacified bowel adjacent to the pancreas mimicking a laceration, fluid in the lesser sac, hematoma around the pancreatic tail arising from the spleen, left kidney, or adrenal, and streak artifacts simulating 1aceration.“6Preoperative identification of pancreatic injury may lead to ERCP

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Fig 21. CT of pancreatic transection. This enhanced CT scan was performed on a 16.year-old female after a “hard” tackle during a football game (she was the first female in an all-male league) after which she complained of severe mid-abdominal pain. The image reveals transection of the pancreas at the level of the neck (arrows) and superior mesenteric artery. There is infiltration of the peripancreatic fat and thickening of the left anterior aspect of the pararenal fascia. (Reprinted with permission.“)

Fig 22. Pancreatic transection. This image was acquired in a 20-year-old man after a motor vehicle accident. There are multiple contusions of the spleen, partial nonperfusion of the upper left kidney, and hemoperitoneum. In addition, there is hemorrhage around the distal pancreas (open arrow) and transection of the pancreatic tail (arrows). These findings were surgically confirmed and the patient underwent a splenectomy, left nephrectomy, and distal pancreatectomy. [Reprinted with permission.“)

Fig 23. Peripancreatic mesenteric hemorrhage. This CT scan of a young women involved in a motor vehicle accident was obtained for mid-abdominal pain. There is extensive infiltration of the peripancreatic fat and transverse mesocolon with high density. The uncinate process is illdefined. At surgery, blood was observed dissecting into the transverse mesocolon and was seen in the pancreatic bed. The pancreatic neck was transected.

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Fig 24. Pancreatic transection A CT scan was performed in a 24-year-old man who complained of “mild” upper-abdominal pain after having been struck by a car. The patient had a transient decrease in blood pressure during initial observation. This CT reveals a huge hemorrhage mass involving the pancreatic head. The superior mesenteric artery was displaced forward (arrow), but the superior mesenteric vein was not visualized. At surgery, transection of the pancreatic head was noted with rupture of the superior mesenteric vein and anterior pararenal hemorrhage. A Whipple procedure was required. (Reprinted with permission.“)

Fig 25. CT of bowel rupture: delayed CT and clinical manifestations. (A) CT scan through the pelvis of a young man involved in a motor vehicle accident shows minimal intraperitoneal fluid (curved arrow) that measured 25 HU. No other CT abnormalities were observed. The patient was clinically asymptomatic. (5) This CT scan was performed 8 hours after the patient developed severe abdominal pain. There is now gross ascites and pneumoperitoneum. A ruptured jejunum was surgically documented.

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Fig 26. CT of bowel perforation. (A) CT scan of a young man involved in motorcycle accident shows gross free intraperitoneal fluid and pneumoperitoneum (arrow). (B) CT image through the mid abdomen shows thickened loops of bowel (arrows). The patient had surgically verified jejunal rupture.

to evaluate duct integrity and help guide management.40-42 Bowel Znjuty Historically, the accuracy of CT detection of bowel injury caused by blunt trauma was believed to be relatively poor. However, recent reports reflecting improved technical CT quality and greater experience in CT interpretation casts doubt on this impression. Bowel injury accompanies blunt abdominal trauma in 4% to 5% of patients with major injury.43The retroperitoneal duodenum is the most common site of bowel injury. Mesenteric injury occurs three times more frequently than bowel injury. Although seat belts have decreasedoverall morbid-

ity and mortality from vehicular trauma, their use has been frequently implicated in the development of bowel injury from abdominal trauma. Concurrent non-bowel injuries are present in 50% of patients with bowel injury.43 Proposed mechanisms of bowel injury include increased intraluminal pressure within the bowel, compression between the spine and impacting body, and shearing from deceleration at points where the bowel is in transit from fixed to free as at the ligament of Treitz, the distal ileum, and the gastroduodenal junction.36,44g45 In somepatients, grossperitoneal signs accompany bowel injury, but in two thirds of patients the classic clinical triad of absent bowel sounds, tenderness, and rigidity is not present.43,44 Mini-

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Fig 27. CT of duodenal rupture. CT shows interruption of the posterior wall of the duodenum (arrow) in a young man following a motor-vehicle accident; he had been wearing a lap safety belt. There is gross anterior pararenal fluid present, but no free intraperitoneal air was detected on the CT scan. At surgery, a rupture of the posterior duodenum was found.

ma1 blood loss and the nonirritative composition and low bacterial counts of small intestine thyme may contribute to the delay in clinical diagnosis.4h Analysis of serum and peritoneal fluid amylase levels lacks both sensitivity and specificity for bowel injury.47 Positive DPL results may be not occur until 3 to 6 hours after injury.43,48

CT evidence of bowel injury includes pneumoperitoneum, best seen adjacent to the anterior superior liver margin (Figs 25 and 26), free intraperitoneal fluid without a known visceral source (Figs 25 and 26) interruption of the intestinal lumen with or without contrast extravasation (Figs 27 and 28), bowel wall thickening (Figs 26 and 29) mesenteric hematoma or infiltration, focal bowel hematoma (Fig 30)

acute obstructive pattern, extraperitoneal gas of unknown etiology, retroperitoneal fluid (nonhemorrhagic) of uncertain source (Figs 27 and 28) mesenteric gas bubbles, and extraluminal fecal material.‘“.4’+4y Lack of pneumoperitoneum in no way excludes the diagnosis of hollow viscous injury.43 The presence of hemoperitoneum without an identifiable source should raise suspicion of a bowelimesenteric injury (Fig 25).4” Currently, the accuracy of CT scanning for detection of bowel injuries remains in question and requires further study using newer CT scanners.3h.43,4h Adrenal Injury

Injury to the adrenal gland following blunt impact as been infrequently described in the

j I / ; :

Fig 28. CT of duodenal rupture. CT image of 3byear-old woman obtained after motor vehicle accident shows abrupt interruption of the third portion of the duodenum at the level of the spine (arrow). Fluid has extravasated through the anterior pararenal space mainly on the right. Rupture of the third portion of the duodenum was surgically confirmed. [Reprinted with permission.“)

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Fig 29. CT of jejunal rupture. CT image obtained after blunt trauma shows marked thickening of several proximal small bowel loops (arrows). No pneumoperitoneum was identified on the scan. Exploration revealed jejunal rupture. (Reprinted with permission.“)

Fig 30. Bowel and/or mesenteric hematoma. This CT scan obtained after blunt abdominal trauma reveals a heterogeneous mass in the right lower quadrant (arrowheads). The finding was believed to represent either a bowel and/or mesenteric hematoma. At surgery, a transrnural small bowel hematoma was identified. (Reprinted with permission.“)

Fig 31. CT of adrenal hemorrhage and “thickened crus” sign. CT image through the upper abdomen acquired after blunt trauma demonstrates a right adrenal hematoma. The enhanced adrenal limbs appear denser than central hematoma (white arrowheads). There is apparent thickening of the right diaphragmatic crus due to adjacent hemorrhage (arrow). (Reprinted with permission.=)

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Fig 32. CT of diffuse adrenal bed hemorrhage. CT scan shows complete disruption of the left adrenal gland with replacement by an irregular hemorrhagic mass (large arrowheads). A normal right adrenal gland is observed. Concurrent hemorrhage in the posterior pararenal space mimics a thickened diaphragmatic crus (small arrowheads). The patient had other major injuries (not shown) requiring surgery at which time an left adrenal laceration and hemorrhage was confirmed. (Reprinted with permission.*5)

literature but probably occurs much more frequently than is recognized. A recent 32-month review of CT studies performed at the Shock Trauma Center found 23 adrenal injuries in 20 patients. No patient had adrenal injury without concomitant injuries in the chest and/or abdomen.50Adrenal injury appeared as mild uniform thickening of the gland (contusion), hematoma arising from the center of the gland and creating a round to oval mass (Fig 31), or diffuse adrenal

disruption and hemorrhage completely replacing the adrenal architecture (Fig 32).“‘-” The majority of adrenal injuries were right-sided which may be secondary to compression of the gland between the liver and the spine. Three patients had bilateral adrenal hemorrhages and one of these became acutely addisonian (Fig 33). Associated findings of adrenal hemorrhage include standing of the periadrenal fat, posterior paraspinal hemorrhage mimicking a thick-

Fig 33. CT of bilateral adrenal hematomas. CT scan of a 35.yearold man after a motor vehicle accident shows discrete oval bilateral central hematomas expanding slightly denser adrenal limbs. Minimal strandlike hemorrhage infiltrates fat posterior to the left adrenal gland. The patient had no clinical sequela related to the bilateral adrenal injury. Both adrenal masses resolved on follow-up CT study. (Reprinted with permission.ffl)

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1



ened diaphragmatic crus (Figs 31 through 33), and inferior vena caval compression (Fig 34). 50 Follow-up CT scans revealed decreasing size and density of the adrenal hematoma with gradual restoration of normal adrenal anatomy. Overall, injury appears innocuous, particularly when unilateral but must be recognized as a potential source of delayed hemorrhage or site of infection in septic patients.50

Fig 34. CT of adrenal bed hemorrhage compressing the inferior vena cava. CT image obtained after blunt torso trauma shows an irregular hemorrhage occupying the right adrenal bed. The mass effaces the posterior aspect of the inferior vena cava (arrowhead). There is slight apparent thickening of right medial diaphragmatic crus.

found only one significant renal injury among 1,080 patients who had only microscopic hematuria following blunt trauma.55 Cass et a154 showed that 93% of patients with microscopic hematuria following trauma had no detectable renal injury by CT scanning.54 Unfortunately, even patients with major renal injuries may exhibit only microscopic or even no hematuria. A normal urine analysis has

Renal Injury

Renal injury is a common complication of major blunt abdominal trauma. At the ShockTrauma Center, blunt impact accounts for 86% of renal injuries with the remainder caused by penetrating wounds.53The indications, timing, and type of diagnostic imaging studies performed in patients with suspected renal trauma are considered in this review. The indications for imaging assessmentof the kidneys following blunt trauma are controversial. In most patients, major renal injuries are accompanied by either gross hematuria and/or hypotension. In two reported series, significant documented renal injury was found in only 6 (1.2%) of 494 patients and 3 (0.8%) of 365 blunt torso trauma victims who had neither gross hematuria or hypotension after trauma.54,55 Hardeman et a155found gross hematuria in 21 (84%) of 2.5 patients with documented renal injury after blunt abdominal trauma. Microscopic hematuria alone is a poor predictor of significant renal injury. Hardeman et a155

Unstable

Microhematuria

Gross Hematuria Hypotensive

Pas Abd + DPL Unrehable Exam

Fig 35. Algorithm suggested for the evaluation of suspected renal injury at the Shock-Trauma Center. Patients who require immediate surgical exploration may be screened for major renal injury by single-film IVP obtained after 3 to 5 minutes either before or during surgery. Patients with gross hematuria and/or transient hypotension should be assessed by CECT (E-CT), particularly with associated lower rib fractures or direct flank impact. Patients with microscopic hematuria and no clinical evidence of intraperitoneal injury may be screened by a triple-film IVP, but should have CECT if there is a clinical suspicion of potential intraperitoneal injury. DPL; diagnostic peritoneal lavage; E-CT, contrast enhanced CT. (Reprinted with permission.53)

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Table 2. Computed

Tomography

Grade 1: Minimal (nonsurgical management) A. Renal contusions(s) B. Superficial parenchymal laceration not extending into the collecting system C. Minimal perinephric/subcapsular hemorrhage D. lntraparenchymal contrast (urine) leak (intravasation) E. Segmental or subsegmental renal infarct Grade 2: Major (surgical versus nonsurgical management)* A. Lacerations extending into the collecting system with limited urine extravasation B. Moderate to large perinephric hemorrhage Grade 3: Catastrophic (surgical management) A. Gross urine extravasation B. Major renal devascularization C. Fragmented/shattered, substantially nonfunctional kidney D. Massive or expanding perinephric hematomat Grade 4: Catastrophic (surgical management) A. Renal pelvis or ureter avulsion-intact kidney B. Ureteral urine leak-intact kidney* *Surgery or nonsurgical management depends on hemodynamic status, unobstructed antegrade urine flow, and stability of size of extraparenchymal urine collection. ISelective angiographic embolization may be suitable alternative to surgery to preserve renal parenchymal function. *Predominantlyfrom penetrating injury. Reprinted with permission.84

been reported in up to 24% of patients with renal artery avulsion,56 whereas another study showed that one third of patients with renal pedicle injury had no gross hematuria.57 Even patients with transection of the renal pelvis or ureter may not necessarily have hematuria.

Fig 36. Minor renal laceration. A superficial linear low density is observed in the posterolatera1 right kidney (arrow). The laceration does not communicate with the collecting system. A small perirenal hematoma (arrowheads) is seen adjacent to the site of laceration. (Reprinted with permission.53)

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Given this complex relationship between the extent of renal injury and hematuria, the need for and type of imaging workup for suspected renal injury is controversial. At the ShockTrauma Center, the imaging studies selected to assess possible renal injury depend on the clinical presentation (Fig 35). A hemodynamically unstable patient who requires urgent surgery will, if time permits, undergo a one-film IVP at 3 to 5 minutes after injection of 100mL of 60% contrast. Although a limited study, this “one-shot” IVP can confirm bilateral contrast excretion and document major renal abnormalities; information is required before surgical exploration. Although IVP without tomography has a 12% false-negative rate for renal contusion compared with contrast enhanced computed tomography (CECT), this injury requires no specific treatment.5x An alert, hemodynamically stable patient with only microscopic hematuria will undergo IVP without tomography. If this study is normal, no further renal workup is performed. If abnormalities are detected, these will be further evaluated by CECT. Patients with either gross hematuria. hypotension not severe enough to warrant immediate surgery, or direct trauma to the renal area with lower rib or lumbar transverse process fractures are initially examined with CECT. Patients who are hemodynamically stable with positive peritoneal lavage, as well as patients

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with decreasing hematocrit of unknown source also undergo CECT given the increased likelihood of concurrent intraperitoneal pathology. CECT has been clearly shown to be more accurate than IVP in assessing the type and extent of renal injury, the extent of perirenal and pararenal hematoma, the viability of renal fragments, and the presence of minor contrast extravasation.59-64CECT also has the advantage of being able to image the entire abdomen for evidence of other injuries.

Fig 38. Segmental traumatic renal infarction. This CT scan obtained after blunt right-flank impact shows a sharply demarcated area of nonperfusion in the medial right upper pole suggestive of renal segmental infarction. (Reprinted with permission.53)

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Previously developed urologic staging systems for renal injury have been adapted to include observations from CT examination (Table 2). Grade 1, minor renal injury, includes small renal contusions, superficial renal lacerations, and small perinephric or subcapsular hematomas (Figs 36 and 37). Grade 1 injuries comprise 75% to 98% of renal injury from blunt trauma.54,58-60Jj3 IVP and CECT show contusions as focal or global renal enlargement withirregular parenchymal enhancement. Attenuation or

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Fig 39. Ureteral thrombus. CT scan of a 22-year-old man with gross hematuria after a fall shows a filling defect in the proximal right ureter (arrow), obstructing the flow of opacified urine into the distal ureter. Note the delayed washout of contrast from the right kidney. The hematuria and clot resolved spontaneously. (Reprinted with permission.“)

focal absence of the collecting system may also occur. Delayed scans occasionally show focal collections of contrast within the renal parenchyma, presumably due to extravasated urine within the renal parenchyma (renal intravasation). Renal lacerations appear as linear or irregular defects of the renal cortex (Fig 36). A sharply demarcated area of decreased renal density may result from renal artery branch avulsion occluding distal perfusion (Figs 4 and 38). CECT may also reveal blood clots within

the renal pelvis or ureter (Fig 39). Grade 1 renal injuries are generally treated by medical management alone. Grade 2, major renal injury, indicates deep lacerations extending into the collecting system with either extrarenal urine extravasation or large perinephric hematoma (Figs 40 and 41). CECT scan is much more sensitive than IVP in detecting urine extravasation and is more accurate in evaluating the severity of extravasation or hemorrhage, as well as the severity of renal

Fig 40. Major renal injury. This CT image revealed a deep right posterior renal laceration extending near the renal pelvis. There is a moderately large perinephric hematoma (arrowheads) and hemorrhagic ascites is present in the right peritoneal cavity. No contrast extravasation was observed on the study. The patient was successfully managed nonoperatively. (Reprinted with permission.s3)

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Fig 41. Major renal injury, urineextravasation. CTimageobtained in patient who sustained blunt torso impact shows gross posterior and medial extravasation of contrast from the left kidney. No significant hemorrhage is observed and the kidney appeared substantially functional. The patient was observed and the urinoma resolved without intervention.

laceration.61@,66At the Shock-Trauma Center, patients with gross urine extravasation or massive renal hemorrhage undergo early surgical exploration. Patients with continued renal bleeding who are hemodynamically stable are referred for angiographic embolization to maximize renal parenchymal salvage. Patients with limited urine extravasation, where antegrade urine flow is not compromised, are usually managed without surgery. Grade 3, catastrophic

Fig 42. Catastrophic renal injury. Extensive perirenal hemorrhage. CT scan through the mid renal level in a young man after motor vehicle accident discloses extensive perirenal hemorrhage and laceration of the lateral left kidney. Some high density regions of clotted blood are noted. The patient required nephrectomy due to recurring hemody namic instability. (Reprinted with permission.“)

renal injury, occurs with renal fragmentation, major devascularization, gross renal extravasation, or a large and rapidly expanding hematoma (Figs 42 and 43).66 Such injuries usually require prompt surgical intervention, but angiographic embolization with Gelfoam (Upjohn Co., Kalamazoo, MI) or coils can be attempted to control bleeding if the patient’s clinical condition permits (see article by Pais elsewhere in this issue).67Renal devascularization most likely

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Fig 43. Catastrophic renal injury. Extensive perirenal hemorrhage with active bleeding. (A) CT image through the upper abdomen in a young man after motorcycle accident indicates marked left perinephric hemorrhage. There is active bleeding into the anterior perinephric space (arrows). Marked hemorrhagic ascites is observed. The small size of the aorta and inferior vana cava are probably a reflection of intravascular volume depletion. (B) More caudal image shows huge extent of perirenal hemorrhage. The patient underwent emergency surgery and a bleeding superior renal artery branch was ligated. The kidney was salvaged.

results from stretching of the renal arteries from rapid deceleration and may either cause immediate avulsion of the vascular pedicle or delayed renal artery thrombosis following initial tearing of the intima (Fig 44). The occlusion typically develops in the proximal one third of the renal artery. On both CECT and IVP, the devascularized kidney may appear smaller than normal and may show no nephrogram.@ Collateral vessels may cause minimal patchy peripheral enhancement (Fig 44).“RNo opacification of the medulla or deep cortex is seen, and there is no excretion of urine. Ongoing hemorrhage may be

shown on CECT with major renal artery laceration (Figs 6 and 43). Angiographic contirmation of renal artery occlusion is not required and serves to decrease the already limited opportunity for renal salvage6”.‘” IVP is less sensitive for assessingrenal vascular occlusion, as nonvisualization of the kidney on IVP may be due to partial renal artery obstruction with sufficient perfusion pressure to maintain renal viability but insufficient perfusion pressure to generate a nephrogram or pyelogram. One must always remember that nonvisualization of the kidney on IVP may also occur with severe renal contu-

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Fig 44. Renal artery occlusion. CT image shows essentially no enhancement or function of the left kidney. Some peripheral cortical perfusion is noted. At surgery, the left renal artery was transected and thrombosed and a left nephrectomy was performed. (Reprinted with permission.“)

sion, subcapsular hemorrhage, renal agenesisor ectopia, or renal artery spasm.51 Grade 4 renal injuries indicate avulsion or disruption of the renal pelvis or ureter which usually occurs at the ureteropelvic junction.‘l These are uncommon injuries that may be casued by severe hyperextension of the spine with stretching of the ureter or renal pelvis.71 CECT reveals an intact functioning kidney with gross urine extravasation (Fig 45). If the ureter

Fig 45. Ureteral avulsion injury. This CT image obtained on an 18-year-old woman who was a pedestrian struck by e car shows gross contrast extravasation into the right anterior perinephric and pararenal space. Some posterior perirenal hematoma is also observed. At surgery, the right ureter was completely transected 3 to 4 cm distal to the ureteropelvic junction. (Reprinted with permission.71)

is incompletely severed, some contrast may fill the distal ureter but complete ureteral disruption will result in an unopacified distal ureter. A retrograde pyelogram is useful to document the site and extent of injury. It must always be remembered that pathologic or malpositioned kidneys are more prone to injury following blunt trauma.‘* Kidneys with tumors, cysts, infection, and partial obstruction are more susceptible to injury, and persistence of microscopic hematu-

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ria following trauma in an older patient should lead to careful evaluation for an underlying tumor. Bladder Injury

Approximately 70% of patients with bladder injury have pelvic fractures and bladder rupture occurs in 5% to 10% of pelvic fractures.73s74 A cystogram is required in all patients with gross hematuria associated with pelvic fractures or major blunt pelvic trauma after exclusion of urethral injury. 74 CT scanning should not be relied on to detect bladder injuries because an adequate level of intravesical pressure obtained cannot be assured even with clamping of an indwelling bladder drainage catheter. Falsely negative CT studies for bladder injury have been reported.74%75 CT scan can be used in conjuction with cystography (CT-cystogram) to detect bladder injury. 76Digital CT radiographs and axial CT images can be combined to increase sensitivity in detection of bladder wall thickening or contrast extravasation. Intraperitoneal bladder (IPB) rupture occurs far less commonly than intraperitoneal rupture and usually involves the bladder dome. On CT scan, IPB rupture is easily diagnosed by visualization of contrast material outlining the pelvic peritoneal recesses,paracolic gutters, and intraloop regions (Fig 46). On rare occasions, bladder contrast may be voided into the vagina and fill the posterior vaginal fornix simulating blad-

Fig 46. lntraperitoneal bladder rupture. CT image through the lower abdomen reveals iodinated urine outlining bowel loops and filling the paracolic gutters. The contrast extravasated from an intraperitoneal bladder leak. (Reprinted with permissi0n.M)

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der rupture. Failure of the contrast to move with a change in patient position helps verify this diagnosis. Extraperitoneal bladder (EPB) rupture occurs more frequently than IPB rupture and usually involves the bladder base. Injury may be result of direct perforation by bone fragments or shearing stressesinvolving the bladder’s ligamentous attachments to displaced sections of the pelvis.” By CT, contrast extravasation generally appears in sites around the bladder base, anterior abdominal wall (space of Ketzius), scrotum, perineum, and perirectal area (Figs 47 and 48). Contrast may track up the retroperitoneum to the level of the kidneys and mimic direct renal injury. 53The extraperitoneal contrast does not change location with a change in patient position and does not conform to the configuration of the intraperitoneal recesses. Extravasation of contrast into the perineum and scrotum confirms disruption of the urogenital diaphragm and urethral injury. Vascular Injury-CT

Diagnosis

Most patients with major vascular injury are hemodynamically unstable and do not undergo CT evaluation. Occasionally, with rapid resuscitation and support some patients will maintain relative hemodynamic stability despite rapid hemorrhage and undergo CT. The powerinjected CT bolus will allow identification of major arterial or venous injuries by virtue of

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extravasation of highly dense material (opacified blood) at the site of injury.” We have noted this phenomenon in some patients with renal, hepatic, splenic, and intercostal artery bleeding and major venous bleeding (NC, common iliac vein) (Figs 5, 6, 17, and 43). Active vascular extravasation can be confused with renal pelvic avulsion with gross urine leakage, bowel rupture with oral contrast leakage, or formation or highly dense blood clot. Recognition of active

Fig48. Extraperitoneal bladder rupture. This CT image obtained through the pelvis after blunt trauma shows a site of bladder-wall disruption [arrow) and extraperitoneal contrast extravasation mainly anterior and lateral to the bladder. lntraperitoneal blood is present posterior to the bladder. (Reprinted with permission.“)

bleeding is crucial to prompt rapid surgical management or angiographic embolization.” COMPLICATIONS

OF ABDOMINAL

TRAUMA

Delayed Hemorrhage

A variety of complications can develop in the victim of blunt abdominal trauma that must be sought both by careful clinical scrutiny and appropriate follow-up imaging assessments.As

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noted above, delayed parenchymal hemorrhage can follow a period of initial hemodynamic stability. So called “delayed splenic rupture” represents an initial failure to diagnose splenic injury by physical findings, DPL, and/or CECT with subsequent clinical manifestation of injury presenting as acute blood loss. The incidence of “delayed” splenic rupture has decreased markedly over the past 30 years as a heightened clinical index of suspicion has developed together with sensitive DPL and CT scanning.78 Still, on occasion, splenic injury will remain occult or appear subtle yet progress to significant delayed hemorrhage (Fig 49). Attention to

Fig 49. Delayed splenic rupture. (A) Admission CT obtained after blunt trauma shows a minimal irregularity at the posterior margin of the spleen (arrow). (B) The patient subsequently developed pain and hypotension 3 days after initial scan and repeat study shows gross splenic hemorrhage (arrows) with hemoperitoneum (arrowheads). The patient required splenectomy. (Reprinted with permission.78)

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optimal splenic parenchymal enhancement should improve diagnostic sensitivity. If suspicious areas of injury are detected, these areas should be re-scanned after repeat bolus injection (50 mL of 60% contrast by power-injector) at 4- or 5-mm intervals through the spleen. Remember, splenic injury contained by the capsule will not be reflected in a positive DPL result. Delayed or recurrent hemorrhage following splenorrhaphy can occur and should be sought in the appropriate clinical circumstances. The use of proximal spienic artery Gianturco coil placement to decrease splenic perfusion pressure in patients with ongoing

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Fig 50. Acute acalculous cholecystitis. CT scan performed in a patient with fever and right up per quadrant pain 2 weeks after trauma shows an enlarged, highdensity gallbladder with very irregular interface with the liver. Several areas of low density in the liver suggest liver parenchy mal involvement. The patient had surgically verified acute acalculous cholecystitis with focal hepatic abscess formation.

splenic hemorrhage has been advocated by Sclafani et al who report encouraging results.79 A prospective controlled study comparing expectant managment, surgery with splenorrhaphy, and splenic artery embolotherapy in patients with splenic injury is needed before this approach will achieve widespread application. On rare occasions, delayed hemorrhage may develop from an initially stable hepatic injury

(Fig 19). Factors such as coagulopathy, proximal (perihilar) injury, penetrating trauma with pseudoaneurysm formation, and low-dose anticoagulation for deep venous thrombosis prophylaxis should increase concern over the possibility of delayed of recurrent hepatic bleeding. In many circumstances, angiographic or CT documented hepatic hemorrhage can best be managed by selective Gelfoam embolization (see

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Fig 52. Acute acalculous cholecystitis. (A) This CT image of a 66-year-old man wlth leukocytosis and fever performed 3 weeks after admission for blunt trauma shows a membrane crossing the gallbladder lumen and an irregular interface of the gallbladder and liver parenchyma. (B) A sonogram of the gallbladder also shows the membrane crossing the gallbladder lumen (open arrows). Surgical pathology verified acalculous cholecystltis with a sloughed necrotic mucosa. (Reprinted with permission.“)

article by Pais elsewhere in this issue). Similarly, hemorrhage of renal origin can often be managed by selective Gelfoam embolization to preserve maximal residual renal parenchymal viability. Infection Sepsis following major blunt injury is responsible for patient death in 44% of patients overall

and 88% of those dying after the first seven days.*OOften the source of sepsis is clinically occult despite aggressive clinical and bacteriologic scrutiny. Septic foci within the abdomen and retroperitoneum may be clinically occult and should be sought when other obvious sources are not found. Intraabdominal sources of infection are most typical in patients with known abdominopelvic injury, particularly if they have

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Fig 53. Infected intraabdominal biloma. In a motor-vehicle accident, a 23-year-old woman sustained a hepatic laceration along the falciform ligament, which was repaired at another institution. The patient became febrile 7 days after surgery. This CT image shows a dense gallbladder with slight wall thickening (G). There was pericholecystic fluid and a large fluid collection in the lesser sac (open arrows). Surgical exploration revealed leakage of bile around the gallbladder and into the lesser sac, a necrotic gallbladder, and an infected biloma. (Reprinted with permission.“)

undergone surgical exploration. However, another source of sepsis, acalculous cholecystitis must be considered in any major trauma victim whether or not abdominal injury or exploration have occurred. A number of risk factors included hyperalimentation, sepsis, hypotension, ventilatory support, and biliary stasis predispose multitrauma patients to this entity.81-83Although biliary scintigraphy is often used to screen for this disease, this procedure has a high false-positive rate in the critically ill patient population, somewhat negating its value. When

Fig 54. Post-traumatic pancreatic fistula with an infected pseudocyst. CT scan obtained in a febrile patient who had sustained a gunshot wound and required a distal pancreatectomy shows fluid collection containing gas adjacent to the distal pancreatic stump (arrows) and suture line. A more rostra1 CT image (not shown) better defined the extent of the collection, believed to represent an infected pseudocyst. An ERCP study showed extravasation of contrast from the distal pancreatic duct. Pus was percutaneously drained from the collection. (Reprinted with permission.“j

an intraabdominal source of sepsis is suspected, CECT with good bowel opacification is the procedure of choice because the entire abdomen and pelvis can be assessedin a short time. Major CT findings suggestive of acalculous cholecystitis include gallbladder wall thickening greater than 4 mm, a subserosal halo of edema, a “fuzzy” interface between the gallbladder and liver parenchyma, low attenuation within the liver adjacent to the gallbladder, a “mucosal slough” sign, and air within the gallbladder wall or lumen (Figs 50 through 52). The presence of

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Fig 55. Spontaneous infection in a paraspinal hematoma. This CT image shows a large abscess in the right paraspinal musculature that was diagnosed unexpectedly during evaluation for septic focus. An abscess in this location was not clinically suspected. Treatment required open drainage and debridement.

ascites and gallbladder wall edema (anasarca) decrease the accuracy of both CT and sonographic diagnosis. Sonography can be used to assessthe gallbladder at the bedside and is a reliable screening test but is less accurate in evaluating the remainder of the abdomen and pelvis.x’-87 Typical sites of intraabdominal infection include subdiaphragmatic abscess after splenectomy, infected pancreatic pseudocyst or biloma, and infection in gravity-dependent sites such as

the pelvis after bowel injury with peritoneal contamination (Figs 53 and 54). Other potential sites of infection included known or unknown areas of intraparenchymal or retroperitoneal hematoma (Fig 55). In many cases, CT or sonographically guided drainage of intraabdominal sites of infection will prove curative particularly when collections are unilocular. Multiple collections or septated collections are best managed surgically but can also be approached percutaneously if clinical circumstances warrant.

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Abdominal computed tomography in blunt trauma.

Abdominal Computed Tomography in Blunt Trauma By Stuart E. Mirvis and Kathirkamanathan INCE THE EARLY 1980s computed tomography (CT) has come to pl...
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