Abdominal air is it in the right or in the wrong place?

Transcription

1 Abdominal air is it in the right or in the wrong place? Poster No.: C-1866 Congress: ECR 2014 Type: Educational Exhibit Authors: M. Drake Perez, M. Diez Blanco, E. Lopez Uzquiza, S. Sánchez Bernal, H. Vidal Trueba, J. Crespo del Pozo ; Santander/ES, 2 3 Suances/ES, SELAYA/ES Keywords: CT, Gastrointestinal tract, Emergency, Abdomen, Diagnostic procedure, Computer Applications-Detection, diagnosis, Education, Ischaemia / Infarction, Inflammation, Fistula DOI: /ecr2014/C-1866 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 29

2 Learning objectives To illustrate, in a simplified and visual way, several cases in which there is air density "out of place". They will be organized by the anatomical region where the air is found: the hepatobiliary area, the abdominal solid organs, the gastrointestinal tract, the portomesenteric venous system, the genito-urinary system and the retroperitoneum. The examples are obtained from the most representative abdominal CT explorations seen in our hospital in the recent years. The aim is to become familiar with the most frequent entities that we must take into account when we face this habitual radiological finding. Page 2 of 29

3 Background Air density in CT studies is one of the four basic densities, and it is defined by the range between -800 to Hounsfield units. This is a normal density inside the gastrointestinal tract. But when it appears outside, it can correspond to a wide spectrum of situations (pathological or not). Plain radiography is usually the first imaging technique in suspected extraluminal air. Nevertheless, especially when air collections are small, the technique must be very accurate. In adults, MDCT is the imaging modality of choice for detecting extraluminal gas in the abdominal region and clarifying the etiology (with some exceptions, since ultrasound can also play an imporant role in the study of these patients). Page 3 of 29

4 Findings and procedure details Intraabdominal and extraluminal air density, organized by anatomic region: 1.- Hepatobiliary area: *Pneumobilia: - Etiology: Secondary to biliary intervention (ERCP +/- sphincterotomy, cholecystectomy ) or, less frequently, due to biliary infection with gas-forming organisms (emphysematous cholecystitis, acute bacterial cholangitis) or fistula to the enteric tract. -Imaging: Linear/serpiginous gas density adjacent to well opacified portal venous radicals and portal veins. It has a central concentration, near porta hepatis (and generally thicker than the pattern found in portal pneumatosis). -In this situation, an ultrasound examination of the patient in supine and oblique positions (demonstrating movement of gas) is the best imaging tool. *Portal vein gas: - Etiology: It is typically an ominous sign, associated to bowel ischemia/infarction. But there are other "benign" causes: Bowel distention, inflammatory bowel disease, gastric ulcer, post-interventions (endoscopy ) - Imaging: Gas density branching in the periphery of the liver (close to the hepatic capsule). Thinner than pneumobilia. *Air density in intrahepatic ligaments: Usually comes from a gastro-duodenal perforation. *Hepatic abscess 2.- Abdominal solid organs: * Emphysematous inflammations: Page 4 of 29

5 Air density within the parenchyma. - Emphysematous pyelonephritis: Etiology: Single or mixed organism infection (E. coli typically). Risk factors: DM (90%), immunodeficiencies, recurrent or chronic urinary tract infections, ureteral obstruction, end-stage renal failure Type 1: (33%) Streaky/mottled gas radiating from medulla to cortex +/- crescent of subcapsular or perinephric gas, parenchymal destruction without fluid. Type 2: (66%) Bubbly gas +/- gas within renal pelvis, renal or perirenal fluid abscesses. - Emphysematous pancreatitis: Infected pancreatic necrosis is a major complication and implies a poorer prognosis (near 50% mortality even with surgical debridement). * Abscess: Up to the 25% of the amebic or pyogenic abscesses present gas bubbles. In the kidney normally they follow acute pyelonephritis that leaded to parenchymal necrosis (type 2). * Trauma: Lineal distribution along the laceration plane. * Iatrogenic (ERCP, nefrostomy, percutaneous ablation, after radiotherapy, chemotherapy, embolization ). 3. Intestine (whether as the origin of the pneumoperitoneum, or found in its wall) *Fistulae: Due to inflammation (diverticulitis, Crohn disease, foreign body), trauma, post-operative state, neoplasm. The imaging tip may be to see gas in the urinary bladder. *Perforations: Due to inflammation, trauma, neoplasm. The situation of the air can help to localize the point of perforation is. - Supramesocolic, gastroduodenal ligament: Gastro-duodenal perforation. Page 5 of 29

6 - Inframesocolic: Sigmoid, appendicitis, small bowel - Retroperitoneal: Esophagus, duodenum, anorectal, retrocecal appendicitis. (They can extend into the peritoneal cavity). *Postsurgical: The most frequent causes of pneumoperitoneum are iatrogenics, and among those, the post-surgical ones are especially important. After an abdominal intervention, residual gas will be absorbed along the first postoperative week (although collections of air can be observed until 4 weeks after). But if there is an increase in the amount of gas instead of a decrease, it should warn about a complication: anastomosis leak, perforation *Pneumatosis of the intestine: Cystic or lineal collections of gas in subserosal or submucosal layers of gastrointestinal tract wall. - Etiology: Primary (15%). Secondary (85%) due to bowel necrosis (necrotizing enterocolitis, bowel infarction), mucosal disruption (ulcers, endoscopy, IBD, pbstruction ). Often accompanied by portal venous gas. -Imaging: Cystic or linear distribution of gas along bowel wall on MDCT. If the etiology is ischemic other findings we can see are: ileus, thickened wall, abnormal enhancement, pneumoperitoneum, mesenteric or portal gas/thrombosis. 4.- Porto-mesenteric venous system: (This subject was partially discuss previously, in the hepatobiliary area point). The gas density found in mesenteric veins and/or porta comes from gastrointestinal tract, through mesenteric interstitium, in the context of pneumatosis of the intestine, or secondary to inflammations, trauma In adults, portomesenteric gas is more frequently related to intestinal ischemia, being a bad prognosis sign. 5.- Genito-urinary: *Fistula: Page 6 of 29

7 Due to trauma (prolonged delivery), surgery, inflammation, radiotherapy, neoplasm MRI is the study of choice to demonstrate a fistulous tract. *Iatrogenic (traumatic instrumentation with urinary catheter ). 5.- Pneumoretroperitoneum *Anterior pararenal space: It is the most common place to find air density in the retroperitoneum. It usually comes from perforations in duodenum (2nd and 3rd portion), ascending/descending colon...; or infection/inflammation in the solid organs (pancreas ) *Posterior pararenal space: Air density in this location comes typically from rectum perforation. *Perirenal space: Gas can be found here due to infections of the kidneys. Page 7 of 29

8 Images for this section: Fig. 1: Pneumobilia post-cholecystectomy (this would be considered a no pathological finding). Page 8 of 29

9 Fig. 2: Portal venous gas in the clinical context of an acute mesenteric ischemia. Page 9 of 29

10 Fig. 3: Air density in the gastrohepatic ligament due to the perforation of a duodenal ulcer. Page 10 of 29

11 Fig. 4: Air density in the gallbladder (arrow in fig.4). There are local inflammatory changes, thickening of its wall, and a fistulous tract into duodenum. The study showed also dilated small bowel, and a gallstone (* in the fig.5) right proximal to the ileocecal valve. Page 11 of 29

12 Fig. 5: Air density in the gallbladder (arrow in fig.4). There are local inflammatory changes, thickening of its wall, and a fistulous tract into duodenum. The study showed also dilated small bowel, and a gallstone (* in the fig.5) right proximal to the ileocecal valve. Page 12 of 29

13 Fig. 6: Patient with septic shock admitted to the intensive care unit of our hospital. Diagnostic CT showed an emphysematous pyelonephritis type I, that affected more than the 50% of the left renal parenchyma (fig. 6). After one month, it developed a type II pyelonephritis (fig 7), showing bubbles of gas within liquid colections in both left renal poles. Page 13 of 29

14 Fig. 7: Patient with septic shock admitted to the intensive care unit of our hospital. Diagnostic CT showed an emphysematous pyelonephritis type I, that affected more than the 50% of the left renal parenchyma (fig. 6). After one month, it developed a type II pyelonephritis (fig 7), showing bubbles of gas within liquid colections in both left renal poles. Page 14 of 29

15 Fig. 8: Emphysematous pancreatitis in a diabetic patient and chronic kidney disease. Page 15 of 29

16 Fig. 9: Air in gastroduodenal ligament and thickening of the duodenal wall due to a gastroduodenal perforation. Page 16 of 29

17 Fig. 10: Air in gastroduodenal ligament and thickening of the duodenal wall due to a gastro-duodenal perforation. Page 17 of 29

18 Fig. 11: Sigmoid perforation. Page 18 of 29

19 Fig. 12: Jejunal diverticular perforation. Page 19 of 29

20 Fig. 13: Jejunal diverticular perforation (arrow: diverticula; (*): extraluminal air). Page 20 of 29

21 Fig. 14: Acute mesenteric ischemia in a patient with atrial fibrillation without anticoagulation. (*): Intestinal pneumatosis. Page 21 of 29

22 Fig. 15: Acute mesenteric ischemia in a patient with atrial fibrillation without anticoagulation. (*): Portal pneumatosis. Page 22 of 29

23 Fig. 16: Sigmo-vesical fistula due to sigma neoplasm, (*) air in the urinary bladder. Page 23 of 29

24 Fig. 17: Sigmo-vesical fistula due to sigma neoplasm, (*) air in the urinary bladder. Page 24 of 29

25 Fig. 18: Cecal perforation due to an intestinal obstruction secondary to adhesions that leaded to a sobredilatation. The air is situated in the anterior pararenal space, and extends laterally and posteriorly. Page 25 of 29

26 Fig. 19: Cecal perforation due to an intestinal obstruction secondary to adhesions that leaded to a sobredilatation. The air is situated in the anterior pararenal space, and extends laterally and posteriorly. Page 26 of 29

27 Fig. 20: Retropneumoperitoneum following a colonoscopy (*) for performing a rectal biopsy. Page 27 of 29

28 Conclusion Air density is always present in abdominal CT examinations. To decide whether it is in its right location or not is decisive for the correct interpretation. Radiologists have to be familiarized with the entities that can lead to intraabdominal and extraluminal gas. Some may be normal findings. But others might be a medical urgency. Interpretation of CT studies must take into account the anamnesis and physical exploration, because the same imaging results can have diverse meanings and prognosis in patients that have different clinical features. Page 28 of 29

29 References * Tirkes et al. Peritoneal and retroperitoneal anatomy and its relevance for cross-sectional imaging. RadioGraphics * Chou CK, Mak CW, Tzeng WS, Chang JM. CT of small bowel ischemia. Abdominal Imaging Jan-Feb; 29 (1): * Peloponissios N et al: Hepatic portal gas in adults: review of the literature and presentation of a consecutive series of 11 cases. Arch Surg 138(12): , * Singh et al. Evolution of imaging for abdominal perforation. Ann R Coll Surg Engl * Díaz Díaz, Forero Cuéllar et al. Gas extraluminal abdominal en imagen. Causas y significado clínico. Revista Colombiana de radiololgía (2): Page 29 of 29