Small Bowel Obstruction

Transcription

1 Acta Radiológica Portuguesa, Vol.XVII, nº 65, pág , Jan.-Mar., 2005 Small Bowel Obstruction Francis J. Scholz, MD Lahey Clinic Tufts University School of Medicine Armed Forces Institute of Pathology Small Bowel Obstruction Impaired passage of contents thru SB. Partial vs Complete ( High Grade ) Intermittent vs Continuous Mechanical vs Paralytic ( Ileus ) Chronic vs Acute SBO Concept to help analyze SB in CT, KUB, SB Series Distention vs Dilatation: 2 variables Dilatation: bowel diameter is larger than expected. May be a few loops or entire SB. May or may not be Distended Distention: bowel has uniform appearance of maximum possible diameter. Like a sausage shaped balloon inflated to its capacity. Appears tensely filled, to capacity. SBO Review Mechanical Classic Acute Complete SBO Simple SBO Closed Loop Obstruction (CLO) Urgent Emergency!!!!!!!! Simple SBO A tapered distension meandering back toward Treitz. A single transition point Chronic Intermittent SBO Classic Appearances Intermittent Chronic SBO Partial SBO Dilated but not distended SBO Motility - Paralytic Ileus Intestinal Pseudo-obstruction Scleroderma Collagen Vasc Radiation enteritis, earliest stage Sprue, MAB diseases DYSMOTILITY is a FUNCTIONAL SBO!!!!! Slow passage acts / looks obstructive Chronic vs Acute SBO Distention vs Dilatation Distended, not (XS) Dilated: Acute, initial SBO Dilated, not Distended: Chronic, intermittent SBO DYSMOTILITIES!! Dilated and Distended: Acute, recurrent SBO Acute Mechanical - initial ARP 81

2 Chronic vs Acute SBO KUB Distention vs Dilatation Distended, not (XS) Dilated : Acute, initial SBO Dilated, not Distended: Chronic, intermittent SBO DYSMOTILITIES!! Dilated and Distended: Acute, recurrent SBO Scleroderma Idiopathic Intestinal Pseudoobstruction Myopathic type > 48 Hours!! KUB Chronic vs Acute SBO Distention vs Dilatation Distended, not (XS) Dilated : Acute, initial SBO Dilated, not Distended: Chronic, intermittent SBO DYSMOTILITIES!! Dilated and Distended: Acute but recurrent SBO Crohns Chronic Idiopathic Intestinal Pseudo - obstruction No cause (readily) apparent. Myopathic forms: More common Dilated, Atonic Neuropathic forms: Spastic, Non propulsive peristalsis Pulsion tics of SB Conceptually like: Diffuse Esophageal Spasm Bloating, Obstruction Prior Colectomy for constipation with Ileo-rectal anastomosis WSE Unobstructed to bulb POLIP Syndrome Polyneuropathy Ophthalmoplegia Leukoencephalopathy Intestinal Pseudo-obstruction Acronym: P-O-L-IP Rare 4 Familial Simon et al, Polyneuropathy, Ophthalmoplegia, Leukoencephalopathy, Pseudoobstruction: POLIP Syndrome; Ann Neurol 1990;28: Rad of POLIP Syndrome 24 Hr Film Slow GI Transit Non-propulsive SB hypermotility LIKE DES Corkscrew esophagus SB Tics from segmental spasm Malabs pattern: wet, moulage, delay T T T T T T 3 Hrs 20 mins UGI MRI: White matter changes, high signal on T2 82 ARP

3 CT: Acute SBO Closed Loop Obstruction Lumen occluded at 2 adj. sites Adhesion, Hernia - Internal, External Tumor, Volvulus Obstructed loop fills w fluid, Distends, elongates Base narrows, loop twists Venous & Art Occlusion results Holy Grail = Transition Point Define Lesion Absent a Lesion = Adhesion Study: Colon -? Collapsed Ileocecal Valve Duodenal Crossing Mesenteric Vessels CT Closed Loop Obstruction (CLO) Closed Loop knot Clustering of SB loops Blocked at two ends Very distended Mesentery: Bunching of engorged vessels SBO above CLO Less distended CT: Acute SBO Points to Remember: Critical to find & Dx SBO, Closed Loop Obst Ischemia may result (or ischemia may cause SBO) May resolve before surg, (NG suction, bezoar passage) Surgeon may Miss at surgery Cure unknowingly by dissection Underestimate degree of disease you Dx SBO - Enema 1. Ileus vs SBO 2. Partial, intermittent 3. If? Is SBO vs LBO (Possibly define very distal SBO cause) SBO - SB Study Partial, intermittent Enteroclysis ARP 83

4 SBO - SB Study Dedicated SB Series Serious SB Series - Freq films & fluoroscopy Spot: Compress & Palpate Oblique & Tangent Valsalva Aphthous Ulcers Adhesion Rad Zig-Zag Crossing Band Acute angulation Spiculation Abrupt diameter transition Bunch / Twist of Mesentery Fixed Loops over time SBO Motility - Paralytic Ileus Intestinal Pseudo-obstruction Sprue, MAB diseases Mechanical Adhesions ~ 50% Tumor Intussuscept, encase Inflammation (SB, Colon Ticitis, Crohns) Volvulus Hernia Bezoar Ischemia Crossing Band BRA Adhesion Causes Benign Adhesions Surgical Inflammatory Radiation Ischemia Neoplastic Adhesions (Carcinoid) Tethering Tenting Adhesion DAN a.jpg Adhesion Types Inter-loop Intra-loop Loop to Solid Organ Loop to Omentum Mesenteric Adhesion (retractile mesenteritis) Combinations of all Multiple Zig-Zag Adhesions DAN a.jpg 84 ARP

5 Tumor - SBO Applecore Matted Mess Extrinsic Compress Intussusception Adhesion Any / all of above Carcinoid SBO 1 Tumor obscured 2 Tumor: Adhesions Extrinsic Mesenteric Mass(es) Calcify Vascular Compromise Intussusception Any or all above WES Intussusception Lead point None : normal physio Tumor Lymphoid hyperplasia Inverted Meckels Sprue Inverted Meckel s Diverticulum Pain Bleeding SBO Intussusc NSAIDs Enterocolitis Indomethacin Aspirin, plain, enteric NSAIDs (Not yet Celebrex, Vioxx COX2s) SB & Rt Colon Disease Strictures Fold Thickening Distorted loops, scars Diaphragms Dx Surgical - pathology Exclude other causes NSAID withdrawal SB CA Anemia, Fe Def Dx: Difficult Late SBO Applecore ARP 85

6 Diaphragm Disease One type of NSAID stricture. Diaphragm-like septae markedly narrowing lumen. Submucosal fibrosis on histo. Scholz FJ, et al. Diaphragmlike strictures of SB associated with use of nonsteroidal antiinflammatory drugs. AJR Am J Roentgenol Jan;162(1): Adhesion Traps Bezoar. SBO results Abdominal Hernias 1.5 % of population 500,000 ops yr External (most) or Internal Hiatal, Inguinal, Femoral, Ant Abd Wall Majority include peritoneal sac & fat Contents: Greater Omentum SB or Colon Other organs possible SBO in Colonic Diverticulitis SB can be sicker than Colon ~5-15% present w SBO 2 Adhesions SB abscess Fistula Abscess Abdominal Hernias By Location Internal vs External Inguinal, Femoral, Sciatic, Hiatal, etc By Type Complete vs Partial (Richter) By Content Littre, Amyand By Severity Reducible Non-Reducible or Incarcerated Ischemic or Strangulated Infarcted Mesenteric Volvulus Assoc w Malrotation - Left Colon, Right SB Weak Treitz Internal Hernia External Hernia Post operative Short / bunched mesentery External Abdominal Hernias Diaphragmatic, Pelvic, Abd Wall Diaphragmatic Esophageal Hiatus Foramen of Bochdalek Foramen of Morgagni Acquired diaphragmatic defects Congenital diaphragmatic defects 86 ARP

7 Morgagni Hernia Embryo defect in fusion of sternal & costal diaphragm Majority on R; Asymptomatic = 10% congenital diaphragm defects True membranous sac Complications 10% Littre s Hernia Pre-existing diverticulum herniates. Colonic Meckel s 50% Inguinal 30% Umbilical External Abdominal Hernias Diaphragmatic, Pelvic, Abd Wall Hernias of Pelvis Inguinal Femoral Obturator Sciatic Vaginal Enterocele Rectal Enterocele Levator Hernia External Abdominal Hernias Diaphragmatic, Pelvic, Abd Wall Abdominal Wall Umbilical Ventral Epigastric Spigelian Parastomal Lumbar Incisional (Anywhere) Obturator Hernia Rare Small Pediatric Umbilical Hernia Congenital outies : Protrusion of fat (viscera) thru patent umbilical ring Rarely symptomatic (Omphalocele: not hernia but failure of abd wall closure: viscera never in abdomen) Richter s Hernia Contains part of antimesenteric wall 90% inguinal - femoral Also parastomal, incisional Prone to strangulation Patent lumen despite strangulation Umbilical Hernia Adult: 4% of all hernias May incarcerate / strangulate bowel / fat Middle age F, usually obese Spont rupture in pregnancy or ascites ARP 87

8 Spigelian Hernia SBO CIA Note hernia under muscle Incisional hernia thru muscle Parastomal Hernias Assoc w any stoma Common Most Asymptomatic Symptoms: Stoma dysfunction Incarceration common Strangulation rare Recurrence, especially w obesity Tangent to Stoma Tangent with Valsalva Incisional Hernias Incarcerated - Strangulated PSH True iatrogenic hernia Common assoc: wound infection Lower incid w transverse incisions Incarceration common (33%) Strangulation rare (5%) Recurrence, esp w obesity SBO upstream Efferent Limb collapsed Neck squeeze Distended Hernia Loop Hernia Sac Fluid (Strang) Compressed Abd Wall KEL MAI Internal Hernias Paraduodenal A 53% Pericecal B 13% Foramen of Winslow C 8% Transmesenteric D 8% Pelvis E 7% Transmesosigmoid F 6% Gahremani & Whalen Curr Prob Radiol 5:1-30,1975 Internal Abdominal Hernias Also: Trans-omental Retro-anastomotic Antecolic Retrocolic Roux -en Y Value of Tangent, with Valvalsa 4 88 ARP

9 Internal Hernias except paraduodenal GOR R para Associated w prior bowel surgery Look for Clips Mesenteric: Bunching Engorgement Twisting Criss-crossed vessels Paraduodenal Hernia R PD Hernia: Ileocolic & R Colic anterior to hernia Sac. Duodenum does not cross between SMA-Aorta. Aorta. All Internal Hernias = < 1% SBO, (LBO) 50% IH = Paraduodenal Mortality high in pre-ct era (20%) Clinically: asymptomatic, pain, SBO, Left 3X > R; M > F Congen failure of fusion mesentery w parietal peritoneum J Comp. Assist. Tomo. 10:542, 1986 No Blood Vessels In Right Gutter Ale R Paraduodenal Left Paraduodenal Hernia Extends into desc & transv mesocolon Stomach displaced to right Colon ant. or inf. to hernia Neck contains IMVein & Left Colic Art. IM Vein displaced ant. by hernia Treitz OK Foramen of Winslow Epiploic Foramen Ant:R free margin of Lesser Omentum. Porta Hepatis to Lesser curve of stomach PortalVein Hepatic Art CBD Right PD Hernia Assoc w absent Lig Treitz Displaces stomach to left Volvulus Cecum toward Lesser Sac SB behind duodenum Into ascend. mesocolon Behind Right & Transv Colon ARP 89

10 Cecal Volvulus into lesser sac SBO Potential in Cecal Volvulus SB follows IC Valve SBO Complex Subject Many Causes Vital Common Acute and Chronic Recurrent Delay in DX disastrous / fatal MUR SBO Khurana B, et al SBO revealed by MDCT; AJR:179, May 2002; Frager D, et al CT of SBO; AJR 1994;162:37-41 Boudiaf M et al CT evaluation of SBO; Radiographics 2001;21: Balthazar EJ, et al Closed Loop and strangulation intestinal obstruction: CT Signs. Radiology 1992; Pre op DX: Infarcting Internal Hernia Assoc w prior bowel surg ( Clips ) See : Mesenteric: Bunching Engorgement Twisting Criss-crossed vessels NSAIDs Enterocolitis Zalev AH, Gardiner GW, Warren RE. NSAID injury to SB. Abdom Imaging Jan-Feb;23(1):40-4. Levi S, de Lacey G, Price AB, Gumpel MJ, Levi AJ, Bjarnason I. "Diaphragm-like" strictures of SB in pts treated with non-steroidal anti-inflammatory drugs. Br J Radiol Mar;63(747): Shumaker DA, Bladen K, Katon RM.NSAID-induced SB diaphragms and strictures diagnosed with intraoperative enteroscopy. Can J Gastroenterol Sep;15(9): Scholz FJ, et al. Diaphragmlike strictures of SB associated with use of nonsteroidal antiinflammatory drugs. AJR Am J Roentgenol Jan;162(1): ISCHEMIA 90 ARP