The Prognostic Value of Portal Venous Gas on CT: An Analysis of Six Cases

Transcription

1 The Prognostic Value of Portal Venous Gas on CT: An Analysis of Six Cases Poster No.: C-1759 Congress: ECR 2015 Type: Educational Exhibit Authors: T. P. Howard, S. Pittman, R. Gullipalli, A. Hartery ; St. John's, Newfoundland/CA, St. John's/CA, St. John's, NL/CA, St.John's, NL/CA Keywords: Patterns of Care, Outcomes, Education, Comparative studies, CT, Conventional radiography, Liver, Gastrointestinal tract, Anatomy DOI: /ecr2015/C-1759 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 16

2 Learning objectives To review the anatomy of the portal venous system. To review the pathophysiology of portal venous gas. To demonstrate several examples of portal venous gas. To illustrate that gas in the portal venous system is not always a sinister finding and does not always confer a poor prognosis. Background The hepatic portal venous system consists of all the veins draining the abdominal digestive tract, extending from the lower esophagus to the upper anal canal (Figure 1). It also receives venous drainage from the spleen and pancreas. The main portal vein arises from the merging of the superior mesenteric vein and the splenic vein and most commonly divides into the right and left portal veins at the porta hepatis, however anatomic variations are not uncommon (Figure 2). These variations include normal branching, trifurcation, 1 and various other arrangements of the left and right portal veins. Normal branching is illustrated in Figure 3. Various imaging modalities have been used for non-invasive evaluation of the portal venous system. Doppler ultrasonography allows valuable functional evaluation of the major tributaries of the portal venous system. Magnetic resonance angiography may be used in patients who are not candidates for CT angiography. Hepatic portal venous gas (PVG) was first described by Wolfe and Evans in 1955 in infants with intra-abdominal catastrophes. Most cases of PVG are attributable to bowel ischemia and necrosis (72%), followed by ulcerative colitis (8%), intra-abdominal abscess (6%), small bowel obstruction (3%) and gastric ulcer (3%). Proposed mechanisms for the 2 generation of portal venous gas include : Escape of gas produced by gas-forming organisms in the bowel lumen or in an abscess which then circulates into the liver, and/or The presence of gas-forming organisms in the portal venous system with passage of gas into the circulation Initially, portal venous gas was associated with a poor prognosis and a mortality of up to 3 75%, and was considered an immediate indication for exploratory surgery. Before the advent of CT scanning, PVG was detected with plain radiography (Figure 4). CT scanning has significantly increased the sensitivity for diagnosing portal venous gas. On CT, PVG Page 2 of 16

3 is notable for peripheral gas lucencies branching out to within the last 2 cm beneath the liver capsule (Figure 5). This differentiates it from centrally located pneumobilia. 3 More recent literature suggests the mortality of PVG is closer to 29-39%, as a broader scope of etiologies are considered and more targeted treatment is possible. Currently documented sources of PVG are described in Table 1. Surgical exploration is now considered unnecessary based on a finding of PVG, and the underlying etiology ultimately determines the treatment strategy and outcome. Table 1: Causes of Hepatic Gas 2,4 Non-Iatrogenic Iatrogenic Bowel ischemia Biliary gas Liver abscess Hepatic artery embolization Hepatic artery thrombosis in a liver Percutaneous tumour ablation transplant Inflammatory bowel disease Colonoscopy Abdominal trauma Barium enema Emphysematous cholecystitis Liver biopsy Ascending cholangitis Oxidized cellulose Diverticulitis Chemotherapy Gastric Ulcer Small bowel obstruction Images for this section: Page 3 of 16

4 Fig. 1: The anatomic origin of portal venous blood. Page 4 of 16

5 Fig. 2: 3D reconstruction of portal venous anatomy demonstrating a minor variant, in which the IMV drains into the SMV. Page 5 of 16

6 Fig. 3: CT MIP image shows classic portal venous anatomy. The main portal vein divides into the left and right portal veins, with the right giving off anterior and posterior branches. Page 6 of 16

7 Page 7 of 16

8 Fig. 4: Plain abdominal film showing portal venous gas, with notable branching radiolucencies. Fig. 5: Axial contrast-enhanced CT demonstrating portal venous gas with characteristic branching densities in the periphery of the liver. Page 8 of 16

9 Findings and procedure details Six cases were collected over a period of six years, each with a finding of PVG on CT. Each case is dicussed below, with a focus on documented diagnosis, interventions implemented, and the clinical outcome of the patient. Case 1 69-year-old male with complex surgical history including segmental lower esophagectomy for spontaneous perforation. One year later, he had total gastrectomy for massive gastric bleed and splenectomy for iatrogenic injury. He had a prolonged postoperative stay in ICU with increasing persistent drainage from his abdominal wound. CT of the abdomen and pelvis with oral contrast in showed portal venous gas, pneumatosis intestinalis involving loops of jejunum in the left upper quadrant, intraperitoneal free air and extraluminal extravasation of oral contrast. Urgent laparotomy was performed with small bowel resection x 2 for ischemic enteritis. The patient returned to ICU and had a complicated post-operative course, eventually expiring secondary to cardiorespiratory failure. Page 9 of 16

10 Fig. 6: Coronal (a) and axial (b & c) CT images with oral contrast show portal venous gas within the liver (red arrows), multiple loops of jejunum within the left upper quadrant that demonstrate bowel wall thickening and pneumatosis intestinalis (yellow arrows), intraperitoneal free air (purple arrows) and extravasation of oral contrast into the peritoneal cavity (green arrows). References: Diagnostic Imaging, Memorial University of Newfoundland, Health Sciences Center/St Clare's Mercy Hospital - St. John's/CA Case 2 67-year-old male presented to the ER with acute onset abdominal pain. The patient was peritonitic on exam and blood work revealed an elevated lactate. Past history included peripheral vascular disease and prior bowel resection for ischemic gut less than one year prior. IV contrast enhanced CT scan showed extensive portal venous gas and small bowel wall thickening. The patient underwent urgent laparotomy and segmental small bowel resection x 2 for ischemic necrosis. The patient did well post-operatively and was discharged home 10 days later. Page 10 of 16

11 Fig. 7: Axial (a,b & d) and coronal (c) IV contrast enhanced CT images demonstrate extensive portal venous gas throughout the liver (red arrows) and in the main portal vein (green arrows), and bowel wall thickening involving multiple loops of small bowel (yellow arrows). Extensive atheromatous disease is seen, particularly involving the SMA (purple arrow). References: Diagnostic Imaging, Memorial University of Newfoundland, Health Sciences Center/St Clare's Mercy Hospital - St. John's/CA Case 3 71-year-old male presented to the ER with a two-week history of diffuse abdominal pain and hypertension. Past surgical history includes aortobifemoral bypass graft and bilateral femoral-tibial bypass grafts for peripheral vascular disease. The patient also had prior laparotomy, sigmoid colectomy and small bowel resection for complications related to an infected abdominal wall hernia mesh. IV contrast enhanced CT showed portal venous gas and bowel wall thickening involving the terminal ileum and cecum. CT also Page 11 of 16

12 demonstrated extensive atheromatous disease and complete occlusion of the SMA. The patient underwent laparoscopy and right hemicolectomy with end ileostomy. Pathology revealed ischemic enterocolitis. Immediately following the laparotomy, interventional radiology performed stenting of a high-grade celiac axis stenosis. The patient did well post-operatively and was discharged home two weeks later. Fig. 8: Coronal (a) and axial (b & c) IV contrast enhanced CT images demonstrate portal venous gas within the liver and intravenous gas within mesenteric veins in the right lower quadrant (yellow arrow). Bowel wall thickening is seen involving the terminal ileum and cecum (green arrow). Sagittal IV contrast enhanced CT image (d) demonstrates extensive atheromatous disease with complete occlusion of the proximal SMA (blue arrow). References: Diagnostic Imaging, Memorial University of Newfoundland, Health Sciences Center/St Clare's Mercy Hospital - St. John's/CA Case 4 Page 12 of 16

13 38-year-old male presented to the ER with nausea, vomiting, fever and diffuse abdominal pain. IV contrast enhanced CT images demonstrated marked thickening of the cecum and terminal ileum, extraluminal foci of free air, and portal venous gas. The patient underwent laparotomy, right hemicolectomy and small bowel resection. Pathology revealed Burkitt lymphoma of the terminal ileum. The patient did well post-operatively and was successfully treated with chemotherapy. No evidence of recurrence five years post-treatment. Fig. 9: Axial (a & b) and coronal (c & d) IV contrast enhanced CT images demonstrate marked thickening of the cecum and terminal ileum (yellow arrows) with extraluminal foci of free air (purple arrows) and fat stranding. Intravenous gas seen in the SMV and its branches (green arrows) and intrahepatic portal veins (red arrows). References: Diagnostic Imaging, Memorial University of Newfoundland, Health Sciences Center/St Clare's Mercy Hospital - St. John's/CA Case 5 54-year-old male with schizo-affective disorder presented to the ER with a three day history of abdominal pain, nausea and vomiting. On exam, note was made of hematemesis and a positive fecal occult blood test. Lactic acid was elevated at 12.0 mmol/l. Imaging appearances were highly concerning for bowel ischemia, however exploratory laparotomy showed only dilated loops of small bowel with no evidence of ischemia. The patient was treated with IV antibiotics and recovered uneventfully. Portal venous gas had resolved on follow-up CT two weeks later. Page 13 of 16

14 Fig. 10: Upright abdominal radiograph (a) shows portal venous gas (red arrow) and multiple dilated loops of air-filled small bowel. Axial (b) and coronal (c) unenhanced CT images confirm the presence of portal venous gas (red arrows) and demonstrate pneumatosis intestinalis (yellow arrow). References: Diagnostic Imaging, Memorial University of Newfoundland, Health Sciences Center/St Clare's Mercy Hospital - St. John's/CA Case 6 69-year-old male with history of schizophrenia presented to the ER with a two day history of abdominal pain, nausea and vomiting. On exam, the patient had RLQ tenderness 9 and guarding. White blood cell count was elevated at 17.2 (10 /L). CT scan showed findings concerning for ischemic colitis. The patient was certified due to agitation and involuntarily admitted. The patient remained clinically well without peritoneal signs and was treated conservatively with oral antibiotics. No operative management. The patient was transferred to a psychiatric hospital four days after admission for uncontrolled psychosis. There, he remained stable without psychosis or agitation and had no further complaints of abdominal pain. Page 14 of 16

15 Fig. 11: Axial (a-d) and coronal (e) IV contrast enhanced CT images demonstrate subtle portal venous gas (red arrows) and a focus of air in the SMV (green arrow). Irregular bowel wall thickening and subtle hypoenhancement are seen involving the hepatic flexure (yellow arrows). References: Diagnostic Imaging, Memorial University of Newfoundland, Health Sciences Center/St Clare's Mercy Hospital - St. John's/CA Conclusion Historically, portal venous gas has been considered an ominous prognostic sign indicating bowel ischemia and necrosis with associated high mortality. Since the advent of CT scanning, more benign causes of PVG have been documented and the recommended course of treatment has shifted from exploratory surgery to proper identification of the etiology underlying the gas. In this analysis, six cases of PVG were assessed. Of the six, bowel ischemia was present in four patients, while one patient was diagnosed with a Burkitt lymphoma, and another deemed idiopathic. Only one patient expired as a direct result of etiology underlying the PVG. These findings, in conjunction with recent literature, suggest that a finding of PVG is not necessarily predictive of increased morbidity or Page 15 of 16

16 mortality. While bowel necrosis remains the commonest cause of PVG, careful evaluation of imaging with consideration of more benign etiologies is required. Personal information References Lee WK et al. (2011). Imaging Assessment of Congenital and Acquired Abnormalities of the Portal Venous System. RadioGraphics 2011; 31: Abboud B et al. (2009). Hepatic portal venous gas: Physiopathology, etiology, prognosis and treatment. World J Gastroenterology. 2009; 15(29): McElvanna K et al. (2012). Hepatic portal venous gas - three non-fatal cases and review of the literature. Ulster Med J 2012;81(2): Shah P et al. (2011). Hepatic Gas: Widening Spectrum of Causes Detected at CT and US in the Interventional Era. RadioGraphics 2011; 31: Page 16 of 16