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Intestinal Obstuction. Hua-dan Xue 2008-11-30. Ileus (intestinal obstruction). Mechanical intestinal obstruction Simple obstruction : occlusion/constriction of bowel lumen Strangulated obstruction : impaired blood supply of obstructed segment Ileus (adynamic/non-obstructive)
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Intestinal Obstuction Hua-dan Xue 2008-11-30
Ileus (intestinal obstruction) • Mechanical intestinal obstruction • Simple obstruction:occlusion/constriction of bowel lumen • Strangulated obstruction:impaired blood supply of obstructed segment • Ileus (adynamic/non-obstructive) • Paralytic & spasm • Derangement impairing proper distal propulsion of intestinal contents Cautions to barium exam due to the possibility of obstruction aggravating
Classification - location • Gastric outlet obstruction: • Only one/two air-fluid levels • Homogeneous mass displacing transverse colon • Duodenal obstruction: • Double-bubble sign; • Frequently normal due to absence of gas from vomiting
Classification - location • Jejunal and ileal obstruction: • Candy cane: >3 loops+>3cm gas-fluid levels+>3~5 hours onset • Disparity in size between obstructed and normal loops • Little/no gas + stool in colon with complete mechanical obstruction after 12-24 hours • Stepladder appearance; string-of-bead; Cave: fluid-distended loops may lead one to overlook obstruction!!!
Classification - location • Colonic obstruction • Dilated colon only • Dilated small bowel (incompetent ileo-cecal valve) • Gas-fluid levels distal to hepatic flexure (fluid is normal in cecum and ascending colon) • Cecum most dilated portion (>10cm will be critical)
Classification – location • Localized ileus • Causes: often associated with adjacent acute inflammatory process (acute pancreatitis, acute appendicitis, etc.) • Sentinel loop: loops near the local peritonitis • Closed-loop obstruction
Closed-loop obstruction • Closed-loop obstruction • Fixation of bowel loop: • Coffee bean sign: gas filled loop • Pseudo-tumor: fluid-filled loop • U-shaped dilated bowel loop • Increasing intra-luminal fluid • Beak sign: point of obstruction • Whirl sign: twisting of bowel
Closed-loop obstruction Large volvulus Beak sign
Classification - etiology • 机械性肠梗阻 • 单纯性肠梗阻:肠管通畅性障碍 • 绞窄性肠梗阻:肠管通畅性障碍伴有血运障碍 • 动力性肠梗阻 • 麻痹性肠梗阻: • 痉挛性肠梗阻: • 血运性肠梗阻:肠系膜动脉血栓或栓塞所致 钡剂造影须慎重使用,钡剂吸收水分会加重梗阻
单纯性肠梗阻 • 阶梯状气液平 • 大跨度肠袢 • 鱼肋征
绞窄性肠梗阻Strangulated obstruction • Triad: • closed-loop obstruction of the involved segment (majority of cases) • Mechanical obstruction proximal to the involved segment • Venous congestion of the involved loop • Abdominal plain film : • signs for volvulus(肠扭转) or closed-loop obstruction + bowel thickening • CT has 63%~100% detection rate!!! • Poor/no enhancement of bowel wall • Mesenteric haziness due to edema
绞窄性肠梗阻 • 假肿瘤征: • 两端闭锁的绞锁肠段内充满大量液体,仰卧位呈肿块影,而站立位或侧卧位水平位片上则在该肿瘤块影上部见一短小的液面 • 咖啡豆征:闭襻 • 小跨度蜷曲肠襻:肠系膜增厚缩短 • 长液面征:张力低、血性液体 • 空回肠换位征:小肠扭转
肠扭转 • 小肠扭转:空回肠换位、花瓣样或香蕉样排列
麻痹性肠梗阻Ileus • Causes: • postoperative • intraabdominal inflammation • ischemic bowel disease • Large + small bowel ±gastric distension • Decreased small bowel distension in serial films • Delayed but free passage of contrast material
Strangulated obstruction • Triad: • Closed-loop obstruction of the involved segment (majority of cases) • Mechanical obstruction proximal to the involved segment • Venous congestion of the involved loop • Abdominal plain film : • Signs for volvulus or closed-loop obstruction + bowel thickening • CT has 63%~100% detection rate!!! • Poor/no enhancement of bowel wall • Mesenteric haziness due to edema
Comparison - Simple obstruction • Stepladder gas-fluid level • Large span loop • Fish-rib appearance
Comparison - Strangulated obstruction • Pseudo-tumor • Coffee bean sign:closed loop • Small span loop:shortening of mesentery • Long gas-fluid level:low tension • Displacement of jejunum and ileum
Volvulus • Small intestine volvulus: • displacement of ileum and jejunum, • banana-like flower-leaves-like form (representing the twisting bowel)
Ileus (paralytic ) • Causes: • Postoperative • Intra-abdominal inflammation • Ischemic bowel disease • Large + small bowel ±gastric distension • Decreased small bowel distension in serial films • Delayed but free passage of contrast material
Finding the reasons… • Post-operation • Infection • Intussusception • Thrombosis • Tumor (extrinsic and intrinsic bowel) • Congenital
Intestinal obstruction • Modalities, Methods and indications 1、Plain abdominal film:acute perforation and obstruction of bowel 2、Barium enema:diagnose and therapy of obstructive disorders, e.g. intussusception, volvulus… 3、CT scan:all kinds of acute abdomen applicable. 4、B-us:solid organ trauma, peritoneal fluid collection, localized abscess, calculi & obstruction, intussusception, acute imflammation.
references • Review manual • Primer of radiology