Pneumatosis Intestinalis: when to worry?

Transcription

1 Pneumatosis Intestinalis: when to worry? Poster No.: C-1441 Congress: ECR 2013 Type: Educational Exhibit Authors: F. Rego Costa, C. Maciel, C. Esteves, L. Melão; Porto/PT Keywords: Gastrointestinal tract, Abdomen, CT, Conventional radiography, Diagnostic procedure, Education, Education and training DOI: /ecr2013/C-1441 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 34

2 Learning objectives Review the imaging features and clinical conditions associated with pneumatosis intestinalis (PI) in the adult population; Highlight key discriminatory imaging features between benign and lifethreatening causes; Emphasize the importance of patient's overall clinical condition in the interpretation of PI. Page 2 of 34

3 Background Definition: PI is an imaging sign (instead of a specific diagnosis/disease) that is the result of an underlying pathologic process and can be defined as the presence of gas within the wall of the gastrointestinal tract. All parts of the gastrointestinal tract may be affected but the small bowel, the colon, or both are mostly involved. Extra intestinal location is rare. Epidemiology: PI in adults typically presents in the fifth to eighth decade. Although the incidence of PI is low (about 0.03% in the general population), its detection appears to be increasing mainly because of increased CT use, but also because of a real increase in incidence (new drugs and surgical procedures are thought to be contributing). Classification: PI can be primary (15%) or secondary (85%) to a wide variety of underlying disorders: Primary PI, also known as pneumatosis cystoides intestinalis, is an asymptomatic, invariably benign idiopathic condition characterized by multiple thin walled cysts in the bowel wall and its mesentery, containing air; Secondary PI is traditionally divided into two categories: benign causes and life-threatening causes. The most common life-threatening cause of PI is intestinal ischemia. Page 3 of 34

4 Table 1: Causes of secondary pneumatosis intestinalis in the adult population. Some of the causes occur under both benign and life-threatening categories. COPD, Chronic obstructive pulmonary disease; PEEP, Positive end-expiratory pressure; AIDS, Acquired immunodeficiency syndrome. References: - Porto/PT Pathogenesis: The pathogenesis of PI is poorly understood (the exact cause is not known), and the range of pathologic conditions associated with its formation suggests that its development is a multifaceted phenomenon. The current knowledge about the pathogenesis relies on two main components/theories: Mechanical: gas passes through the mural portion of the bowel wall. This can occur for a number of reasons - mucosal disruption (inflammation, necrosis, ulceration or trauma can injury the mucosa disturbing its normal continuity); increased mucosal permeability (defective immune barrier as in patients with immunodeficiency or treated with immunosuppressive/cytotoxic medications); increased transabdominal pressure (bowel obstruction, chronic obstructive pulmonary disease, trauma or vomiting can lead to direct gas diffusion in the setting of an intact mucosal barrier). Usually, a variable Page 4 of 34

5 combination of these factors will contribute to the dissection of gas into intramural compartments; Bacterial: the origin of the gas. Bacteria are thought to support the presence of intramural gas in PI mainly by two mechanisms: overgrowth and direct invasion of the bowel wall - factors that favor the dissection of gas are the same ones to facilitate bacterial invasion of intramural compartments; modification of intraluminal gas content - this creates a gas gradient between the intestinal lumen and blood (primarily through superproduction of hydrogen) which will promote diffusion of gas across the resistive bowel wall ("counterperfusion supersaturation" phenomenon). Clinical features: The signs and symptoms of PI are normally associated with the underlying disorder rather than being a consequence of the presence of intramural gas. When PI is due to benign causes, patients are usually asymptomatic. Some patients may have abdominal pain, diarrhea, constipation, bloody stools or weight loss. Physical examination is rarely abnormal unless there are peritoneal irritation signs in cases of PI due to life-threatening causes. The pattern or extent of PI does not correlate well with the severity of symptoms or of the underlying disease. Laboratory data can provide important clues in determining if PI is life-threatening. The combination of PI and a serum lactic acid level of > 2 mmol/l were associated with a greater than 80% mortality rate. Page 5 of 34

6 Images for this section: Table 1: Causes of secondary pneumatosis intestinalis in the adult population. Some of the causes occur under both benign and life-threatening categories. COPD, Chronic obstructive pulmonary disease; PEEP, Positive end-expiratory pressure; AIDS, Acquired immunodeficiency syndrome. - Porto/PT Page 6 of 34

7 Imaging findings OR Procedure details PI can be detected on plain abdominal radiographs but CT is the most sensitive imaging test and is usually required. Abdominal radiographs are frequently insensitive to detect initial stages of PI or to evaluate the underlying pathology; CT is the best imaging method for the diagnosis of PI because of its capacity for detecting even small intramural gas collections, elucidate unclear radiographic findings and also to search for potential causes. Gas patterns of PI presented at CT vary considerably- linear, bubble, curvilinear or circular low-density gas collections can be seen in the bowel wall. Sometimes there is a combination of these patterns. Gas may be localized or diffuse throughout the gastrointestinal tract. The circular form of PI is usually benign and most often seen with pneumatosis cystoides intestinalis. Linear or bubble PI can be due to both benign and life-threatening causes, and its appearance alone does not permit differentiation between them. Air trapped within bowel contents or between mucosal folds can mimic PI. This "pseudo-pneumatosis" may be difficult to differentiate from true PI. Gas distribution and "additional CT findings" are useful in the differentiation of "pseudopneumatosis", benign PI and life-threatening causes of PI. The presence of the following increases the possibility of PI due to a life-threatening cause and they should be actively looked for: Small extension of PI (within a specific vascular distribution) Thickening of the bowel wall Absent or intense mucosal enhancement Dilated bowel due to obstruction Hepatic portal or portomesenteric venous gas Arterial or venous thrombus occlusion Free intraperitoneal fluid (ascites) Solid organ infarction (liver, spleen, kidney) Mesenteric fat stranding Intraperitoneal or retroperitoneal free air occupies a unique position. It can be seen with PI due to life-threatening or benign causes (associated with the rupture of serosal and subserosal cysts). Page 7 of 34

8 Fig. 1: 75 year-old man came to the hospital with acute onset of colickly left flank pain. Image (a) and (b): contrast-enhanced CT scan reveals intramural gas (pneumatosis) of the caecum and ascending colon (blue arrows). Despite this pattern of localized PI, there were no additional "worrisome" signs indicating a life-threatening cause. Image (c) and (d): CT scan of the same patient shows pyelocalyceal ectasia with a pelvis AP diameter of 17mm (orange arrow) which appears to be caused by an obstructive 6 mm ureteral stone (green arrow). There is also some stranding of the perinephric fat (arrowhead). These findings are suggestive of the final diagnosis of obstructive pyelonephritis. PI resolved with treatment of the underlying disorder. References: - Porto/PT Page 8 of 34

9 Fig. 2: 75 year-old man with chronic obstructive pulmonary disease, was hospitalized because he had increased dyspnea and cough. Image (a) and (b): contrast-enhanced CT scan shows bubbly parietal pneumatosis of the transverse colon (blue arrows), without any additional CT findings. In this case, pneumatosis had a benign cause. Patient was treated for a respiratory infection and then discharged. References: - Porto/PT Page 9 of 34

10 Fig. 3: 67 year-old woman with a history of microscopic polyangiitis. Image (a) and (b): contrast-enhanced CT scan shows linear pneumatosis in a dilated caecum and ascending colon (blue arrows). In this case, the presence of localized PI, bowel dilation, diminished wall enhancement (blue arrows), mesenteric fat stranding (asterisk) and a small amount of free intraperitoneal fluid (arrowheads) are indicators of a possible life-threatening cause for PI. Patient underwent exploratory surgery which confirmed the diagnosis of ischemic colitis. References: - Porto/PT Page 10 of 34

11 Fig. 4: 49 year-old woman suffering from chronic headache came to the emergency department with severe abdominal pain after self medication with a NSAID. Image (a) and (b): contrast-enhanced CT scan demonstrates parietal pneumatosis of the gastric fundus (blue arrows). This finding alone could not be alarming (pneumatosis might be a consequence of a peptic ulcer) but some additional signs point toward the severity of the case: sudden onset of pain, thinning and diminished enhancement of the gastric fundus wall (blue arrows), intraperitoneal free air (red arrow) adjacent to the stomach. Altogether, these findings led to the diagnosis of gastric wall perfuration which was confirmed surgically. References: - Porto/PT Page 11 of 34

12 Fig. 5: 82 year-old man presented with marked abdominal distension associated with vague abdominal pain and without any signs of peritoneal irritation. Image (a): contrastenhanced CT scan shows caecum and ascending colon dilation with parietal thinning and bubble-like pneumatosis (blue arrows). Image (b): CT scan of the same patient indicates that the obstructive cause for the colon dilation was sigmoid and rectal fecal impactation (green arrows). References: - Porto/PT Page 12 of 34

13 Fig. 6: 74 year-old man with psychiatric illness was brought to the hospital after ingestion of nitric acid (corrosive agent). Image (a): CT scan demonstrates thinning of the gastric and jejunal walls associated with linear pneumatosis (blue arrows). Image (b): in one axial view, CT scan shows thinning of the gastric wall with linear pneumatosis (blue arrow), free intraperitoneal air (red arrow) and a small amount of hepatic portal venous gas (arrowhead). Image (c): irregularity and thickening of distal esophagus (orange arrow) was another consequence of the ingestion of the corrosive agent. Patient died 2 days after this CT despite surgical intervention. References: - Porto/PT Page 13 of 34

14 Fig. 7: 74 year-old man with a history of cerebral vascular disease suffered from acute intense abdominal pain. Image (a): CT scan shows dilation of the caecum and ascending colon, diminished wall enhancement and pronounced pneumatosis (blue arrows). In addition, free intraperitoneal fluid (green arrow) is a contributing sign to the picture of a life-threatening PI. Patient had ischemic colitis and was treated surgically. References: - Porto/PT Page 14 of 34

15 Fig. 8: 86 year-old woman presents with poorly localized severe abdominal pain of acute onset, nausea and vomiting. Image (a): contrast-enhanced CT scan demonstrates ileal dilation (periumbilical and right flank) with hypoenhancement and bubbly parietal pneumatosis of the bowel wall (blue arrows). There is mesenteric fat stranding (arrowhead). Image (b): CT scan of the same patient reveals hepatic portal venous gas that was more prominent in the left lobe (red arrow). Image (c): 10mm occlusive thrombus in the superior mesenteric artery (orange arrow) was discovered to be the cause of the final diagnosis of mesenteric ischemia. Image (d): Abdominal radiograph taken few minutes earlier does not clearly show pneumatosis, highlighting its low sensitivity in the detection of this sign. References: - Porto/PT Page 15 of 34

16 Fig. 9: 85 year-old man presented with acute abdominal pain refractory to analgesics. Image (a) and (b): contrast-enhanced CT scan shows parietal pneumatosis of a gastric wall segment and some jejunal loops (blue arrows) together with portal venous gas (red arrows), suggesting a worrisome cause of PI. Patient underwent surgery which confirmed the diagnosis of gastric and jejunal ischemia. References: - Porto/PT Page 16 of 34

17 Fig. 10: 81 year-old woman with dementia was brought to the emergency department because she was unresponsive to stimulus. Image (a), (b) and (c): contrast-enhanced CT scan exhibits pneumatosis of numerous loops of small intestine (blue arrows) along with portal venous gas (red arrows). Portal venous gas differs from biliary gas in having a more peripheral location in the liver, whereas biliary air is more central. Image (c): in this sagittal view, it is possible to spot arterial thrombosis of the thoracic aorta, superior mesenteric and also a left atrial thrombus (orange arrows). The presence of pneumatosis associated with these exuberant additional findings easily led to the diagnosis of a life-threatening mesenteric ischemia. Patient died a few hours later. References: - Porto/PT Page 17 of 34

18 Fig. 11: 92 year-old man suffering from abdominal distention, obstipation and vague abdominal discomfort when he was hospitalized. Image (a): contrast-enhanced CT scan demonstrates localized pneumatosis of a dilated caecum (blue arrow). Image (b): the cause for the dilation and consequent ischemic suffering of the right colon is shown to be an obstructive tumor in the descending colon (green arrow). References: - Porto/PT Page 18 of 34

19 Fig. 12: 69 year-old woman was carried to the emergency department unconscious. She was diagnosed with an acute myocardial infarction with cardiogenic shock (Killip class IV). Image (a) and (b): CT scan reveals gastric dilation associated with hypoenhancement and linear pneumatosis of the wall of the gastric fundus (blue arrows). Despite the absence of additional CT findings pointing to a worrisome cause of PI, in face of this clinical presentation, the most likely diagnosis is gastric ischemia due to hypoperfusion. Patient died 1 day later. References: - Porto/PT Some typical CT findings of "pseudo-pneumatosis" are worth mention, because awareness can prevent an erroneous diagnosis: Limited to the caecum and ascending colon (because of an admixture of liquid stool and gas); Ending at a free gas-fluid level within the bowel lumen; Irregularly punctuated gas column pattern. Page 19 of 34

20 Images for this section: Fig. 1: 75 year-old man came to the hospital with acute onset of colickly left flank pain. Image (a) and (b): contrast-enhanced CT scan reveals intramural gas (pneumatosis) of the caecum and ascending colon (blue arrows). Despite this pattern of localized PI, there were no additional "worrisome" signs indicating a life-threatening cause. Image (c) and (d): CT scan of the same patient shows pyelocalyceal ectasia with a pelvis AP diameter of 17mm (orange arrow) which appears to be caused by an obstructive 6 mm ureteral stone (green arrow). There is also some stranding of the perinephric fat (arrowhead). These findings are suggestive of the final diagnosis of obstructive pyelonephritis. PI resolved with treatment of the underlying disorder. - Porto/PT Page 20 of 34

21 Fig. 2: 75 year-old man with chronic obstructive pulmonary disease, was hospitalized because he had increased dyspnea and cough. Image (a) and (b): contrast-enhanced CT scan shows bubbly parietal pneumatosis of the transverse colon (blue arrows), without any additional CT findings. In this case, pneumatosis had a benign cause. Patient was treated for a respiratory infection and then discharged. - Porto/PT Page 21 of 34

22 Fig. 3: 67 year-old woman with a history of microscopic polyangiitis. Image (a) and (b): contrast-enhanced CT scan shows linear pneumatosis in a dilated caecum and ascending colon (blue arrows). In this case, the presence of localized PI, bowel dilation, diminished wall enhancement (blue arrows), mesenteric fat stranding (asterisk) and a small amount of free intraperitoneal fluid (arrowheads) are indicators of a possible lifethreatening cause for PI. Patient underwent exploratory surgery which confirmed the diagnosis of ischemic colitis. - Porto/PT Page 22 of 34

23 Fig. 4: 49 year-old woman suffering from chronic headache came to the emergency department with severe abdominal pain after self medication with a NSAID. Image (a) and (b): contrast-enhanced CT scan demonstrates parietal pneumatosis of the gastric fundus (blue arrows). This finding alone could not be alarming (pneumatosis might be a consequence of a peptic ulcer) but some additional signs point toward the severity of the case: sudden onset of pain, thinning and diminished enhancement of the gastric fundus wall (blue arrows), intraperitoneal free air (red arrow) adjacent to the stomach. Altogether, these findings led to the diagnosis of gastric wall perfuration which was confirmed surgically. - Porto/PT Page 23 of 34

24 Fig. 5: 82 year-old man presented with marked abdominal distension associated with vague abdominal pain and without any signs of peritoneal irritation. Image (a): contrastenhanced CT scan shows caecum and ascending colon dilation with parietal thinning and bubble-like pneumatosis (blue arrows). Image (b): CT scan of the same patient indicates that the obstructive cause for the colon dilation was sigmoid and rectal fecal impactation (green arrows). - Porto/PT Page 24 of 34

25 Fig. 6: 74 year-old man with psychiatric illness was brought to the hospital after ingestion of nitric acid (corrosive agent). Image (a): CT scan demonstrates thinning of the gastric and jejunal walls associated with linear pneumatosis (blue arrows). Image (b): in one axial view, CT scan shows thinning of the gastric wall with linear pneumatosis (blue arrow), free intraperitoneal air (red arrow) and a small amount of hepatic portal venous gas (arrowhead). Image (c): irregularity and thickening of distal esophagus (orange arrow) was another consequence of the ingestion of the corrosive agent. Patient died 2 days after this CT despite surgical intervention. - Porto/PT Page 25 of 34

26 Fig. 7: 74 year-old man with a history of cerebral vascular disease suffered from acute intense abdominal pain. Image (a): CT scan shows dilation of the caecum and ascending colon, diminished wall enhancement and pronounced pneumatosis (blue arrows). In addition, free intraperitoneal fluid (green arrow) is a contributing sign to the picture of a life-threatening PI. Patient had ischemic colitis and was treated surgically. - Porto/PT Page 26 of 34

27 Fig. 8: 86 year-old woman presents with poorly localized severe abdominal pain of acute onset, nausea and vomiting. Image (a): contrast-enhanced CT scan demonstrates ileal dilation (periumbilical and right flank) with hypoenhancement and bubbly parietal pneumatosis of the bowel wall (blue arrows). There is mesenteric fat stranding (arrowhead). Image (b): CT scan of the same patient reveals hepatic portal venous gas that was more prominent in the left lobe (red arrow). Image (c): 10mm occlusive thrombus in the superior mesenteric artery (orange arrow) was discovered to be the cause of the final diagnosis of mesenteric ischemia. Image (d): Abdominal radiograph taken few minutes earlier does not clearly show pneumatosis, highlighting its low sensitivity in the detection of this sign. - Porto/PT Page 27 of 34

28 Fig. 9: 85 year-old man presented with acute abdominal pain refractory to analgesics. Image (a) and (b): contrast-enhanced CT scan shows parietal pneumatosis of a gastric wall segment and some jejunal loops (blue arrows) together with portal venous gas (red arrows), suggesting a worrisome cause of PI. Patient underwent surgery which confirmed the diagnosis of gastric and jejunal ischemia. - Porto/PT Page 28 of 34

29 Fig. 10: 81 year-old woman with dementia was brought to the emergency department because she was unresponsive to stimulus. Image (a), (b) and (c): contrast-enhanced CT scan exhibits pneumatosis of numerous loops of small intestine (blue arrows) along with portal venous gas (red arrows). Portal venous gas differs from biliary gas in having a more peripheral location in the liver, whereas biliary air is more central. Image (c): in this sagittal view, it is possible to spot arterial thrombosis of the thoracic aorta, superior mesenteric and also a left atrial thrombus (orange arrows). The presence of pneumatosis associated with these exuberant additional findings easily led to the diagnosis of a lifethreatening mesenteric ischemia. Patient died a few hours later. - Porto/PT Page 29 of 34

30 Fig. 11: 92 year-old man suffering from abdominal distention, obstipation and vague abdominal discomfort when he was hospitalized. Image (a): contrast-enhanced CT scan demonstrates localized pneumatosis of a dilated caecum (blue arrow). Image (b): the cause for the dilation and consequent ischemic suffering of the right colon is shown to be an obstructive tumor in the descending colon (green arrow). - Porto/PT Page 30 of 34

31 Fig. 12: 69 year-old woman was carried to the emergency department unconscious. She was diagnosed with an acute myocardial infarction with cardiogenic shock (Killip class IV). Image (a) and (b): CT scan reveals gastric dilation associated with hypoenhancement and linear pneumatosis of the wall of the gastric fundus (blue arrows). Despite the absence of additional CT findings pointing to a worrisome cause of PI, in face of this clinical presentation, the most likely diagnosis is gastric ischemia due to hypoperfusion. Patient died 1 day later. - Porto/PT Page 31 of 34

32 Conclusion As an imaging sign, PI lacks interpretation. The importance of PI depends on the nature and severity of the underlying condition. When detected, it must be first integrated in the clinical context. A careful look for life-threatening signs, namely "additional CT findings", integration with clinical symptoms, physical examination, laboratory test results and knowledge of the patient clinical background are essential tools to a weighted approach. Page 32 of 34

33 References Morris M, Gee A, Cho S, Limbaugh K, Underwood S, Ham B, Schreiber M. Management and outcome of pneumatosis intestinalis. Am J Surg 2008; 195: Ho L, Paulson E, Thompson W. Pneumatosis Intestinalis in the Adult: Benign to Life-Threatening Causes. AJR 2007; 188: Kernagis L, Levine M, Jacobs J. Pneumatosis intestinalis in patients with ischemia: correlation of CT findings with viability of the bowel. AJR 2003; 180: St Peter S, Abbas M, Kelly K. The spectrum of pneumatosis intestinalis. Arch Surg. 2003; 138: Wiesner W, Mortele K, Glickman J, Ji H, Ros P. Pneumatosis intestinalis and portomesenteric venous gas in intestinal ischemia: correlation of CT findings with severity of ischemia and clinical outcome. AJR 2001; 177: Hosomi N, Yoshioka H, Kuroda C. Pneumatosis Cystoides Intestinalis: CT findings. Abdominal Imaging 1994; 19: Feczko P, Mezwa D, Farah M, White B. Clinical significance of pneumatosis of the bowel wall. Radiographics 1992; 12: Page 33 of 34

34 Personal Information Francisco Rego Costa Radiology Department, Hospital de São João - Porto, Portugal Oporto Medical University Head of Department: Prof. Dra. Isabel Ramos Page 34 of 34