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Abdominal Pain and Bowel Obstruction
Mike Goodwin CRASH Course October, 2010
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Abdominal Pain - Approach
History Physical Labs Imaging Provisional Dx
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History PQRST AAA etx But don’t forget PSx Bowel/Gyne/Urol ROS
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Physical Exam Complete General appearance/vitals/H+N/Chest Abdo:
Rigidity Rebound Guarding IPPA DRE / Pelvic / Groin / Flank-CVA
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Labs Everyone: CBC, lytes BUN Cr LFT, Bili, Amylase/Lipase, lactate
Urinalysis Urine Preg
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Imaging AXR 3-views Free air Distended bowel/air-fluid
Calcifications (panc or kidney/ureter) US If GS disease suspected Lower abdo pain in female
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Imaging CT Abdo Test of choice for most patients
Protocols to minimize contrast nephropathy
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Bowel Obstruction: Overview
History Etiology Pathophysiology Clinical presentation Imaging Management Special considerations
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Causes of Small Bowel Obstruction in Adults
Lesions Extrinsic to the Intestinal Wall Lesions Intrinsic to the Intestinal Wall Intraluminal/Obturator Obstruction
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Lesions Extrinsic to the Intestinal Wall
Adhesions (usually postoperative) Neoplastic Carcinomatosis Extraintestinal neoplasms Hernia External (e.g., inguinal, femoral, umbilical, or ventral hernias) Internal (e.g., congenital defects such as paraduodenal, foramen of Winslow, and diaphragmatic hernias or postoperative secondary to mesenteric defects Intra-abdominal abscess
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Lesions Intrinsic to the Intestinal Wall
Congenital Malrotation Duplications/cysts Inflammatory Crohn’s disease Infections Tuberculosis Actinomycosis Diverticulitis Neoplastic Primary neoplasms Metastatic neoplasms Traumatic Hematoma Ischemic stricture Miscellaneous Intussusception Endometriosis Radiation enteropathy/stricture
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Intraluminal/Obturator Obstruction
Gallstone Enterolith Bezoar
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Common causes of small bowel obstruction in industrialized countries.
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Pathophysiology Early: Increased motility & contractility
Bowel dilation, fluid/lytes accumulate in lumen and bowel wall Third spacing, intravascular volume depletion
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Bowel obstruction Increased intraluminal pressure Decreased mucosal blood flow Progressive Ischemia Perforation & Peritonitis
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Clinical Diagnosis History Colicky abdominal pain Nausea / vomiting
Abdominal distension Failure to pass flatus / feces
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Physical Examination Vitals: Tachycardia, hypotension Abdomen:
Distension Surgical scars Bowel sounds, increased or decreased Localized tenderness / rebound / guarding suggests strangulation Hernia exam (ventral, groin, etc) Rectal exam: Rectal masses Blood – suggesting ischemia, malignancy
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Radiology Plain Abdo X-Rays Confirm Diagnosis
Localize obstruction to small bowel or colon Evidence of complete or incomplete
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Figure 46-13 Plain abdominal radiographs of a patient with a complete small bowel obstruction. A, Supine film shows dilated loops of small bowel in an orderly arrangement, without evidence of colonic gas. B, Upright film shows multiple, short, air-fluid levels arranged in a stepwise pattern. (Courtesy of Melvyn H. Schreiber, M.D., The University of Texas Medical Branch.)
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*Suggests ischemia/strangulation
Plain X-ray Features Dilated Small Bowel (>3 cm) Multiple air-fluid levels Colonic gas pattern Normal / Dilated (Ileus or partial obstruction) Absence of gas c/w complete obstruction *Thickened bowel wall *Pneumatosis intestinalis *Suggests ischemia/strangulation
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Plain X-rays Lappas et al 2001 Review of 12 AXR findings with SBO
Combination of Air-fluid levels of different heights in the same bowel loop Mean air-fluid level diameter of 2.5 cm or greater Most predictive of a high-grade partial or complete SBO
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AXR Disadvantages 20-30% false negative rate
Does not localize site of obstruction Does not establish etiology of obstruction
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CT Scan 95% sensitive 96% specific
95% accurate in determining the presence of complete or high-grade SBO Shows site and cause of obstruction in 95% of instances Less accurate for partial SBO (50% some studies)
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CT for SBO CT performed with IV and PO contrast
High-grade SBO seen even with no contrast Lesser grades of obstruction seen with PO contrast IV contrast for assessment of bowel wall for signs of edema or ischemia.
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CT Findings in Patients with Small Intestinal Obstruction
Type of Obstruction Findings Simple obstruction, partial or complete Proximal bowel dilatation Discrete transition zone with collapsed distal small bowel No passage of oral contrast beyond the transition zone Little gas or fluid in colon
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Figure Abdominal computed tomography (CT) images of two patients with adhesive small bowel obstruction (SBO). The image on the left (A) shows fluid-filled loops of ileum proximal to a transition point at the site of obstruction (arrow); decompressed bowel is seen distal to the obstruction
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CT Findings in Patients with Small Intestinal Obstruction
Type of Obstruction Findings Closed-loop obstruction Bowel Wall Changes U-shaped, distended, fluid-filled bowel loop Whirl sign Beak sign Mesenteric Changes Radial distribution dilated bowel loops Thickened mesenteric vessels converging toward point of obstruction
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Figure Abdominal computed tomography (CT) images of patients with intestinal obstruction. A, A patient with a closed-loop obstruction in which the small intestine twisted around omentum that was adherent to the anterior abdominal wall (arrow). Note the massively dilated loops of contrast-filled proximal intestine on the right side of the abdomen and the fluid-filled loops of bowel containing no contrast on the left. In the center of the abdomen is a tightly twisted segment of bowel (“whirl sign”) consisting of the site of torsion with obstruction of the afferent and efferent limbs of the intestine. B, A patient with strangulated obstruction, evidence of which includes bowel wall thickening (blue arrow), mesenteric stranding (green arrow), and ascites (asterisk).
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CT Findings in Patients with SBO
Type of Obstruction Findings Strangulated Obstruction Bowel Wall Changes Bowel wall thickening Target sign Pneumatosis intestinalis Dec. bowel wall enhancement Mesenteric Changes Blurring of mesenteric vessels Obliteration of mesentery and vessels Engorgement of mesenteric vasculature Other Ascites
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B, A patient with strangulated obstruction, evidence of which includes bowel wall thickening (blue arrow), mesenteric stranding (green arrow), and ascites (asterisk).
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When to Order CT? Clinical presentation or abdominal films nondiagnostic Hx of abdominal malignancy Immediate postsurgical patients Patients who have no history of abdominal surgery
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Barium / Contrast Studies
History of recurring obstruction Low-grade mechanical obstruction Defines the obstructed segment and degree of obstruction
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Gastrograffin Swallow in Adhesive SBO, Cochrane Review, 2004
Diagnostic Gastrofraffin seen in the cecum on AXR within 24 hours predicts resolution Sensitivity of 0.96, specificity of 0.96 Therapeutic Hospital length of stay 2-3 days shorter in non-operative patients Studies prospective, non-blinded
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Simple Versus Strangulating Obstruction
Classic signs: Fever WBC inc Constant Abdo pain But no parameters reliably detect strang. CT findings detect late ischemic changes
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Treatment – Nonoperative
Fluid resuscitation IV resuscitation with isotonic saline Electrolyte replacement Monitor urine output Tube decompression Empties stomach Reduces aspiration risk No benefit to long intestinal tubes In partial obstruction: 60-85% success rate
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Treatment - Operative Complete obstruction
Generally mandates operation Some have argued for nonoperative approach in selected patients 12-24hr delay of surgery is safe >24hr delay is unsafe
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Operative Technique Dependent on underlying problem
Adhesive band: Lysis of adhesions Incarcerated hernia: manual reduction and closure of defect *Presence of hernia with SBO mandates OR Malignant tumors: Difficult challenge Diverting stoma Resection / anastamosis Enteroenterostomy
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Intestinal Viability at Surgery
Release obstructed segment Place in warm sponge x minutes If normal colour and peristalsis: return to abd Doppler probe adds little to clinical judgment (Bulkley, 1981) Fluorescein may be useful in difficult cases “Second look” in 24 hrs if questionable viability or if clinically deteriorates post-op
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Laparoscopy in Acute SBO?
Criteria: Mild distension Proximal obstruction Partial obstruction Anticipated single-band obstruction No matted adhesions / carcinomatosis
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Special Considerations: Recurrent Adhesions
Multiple agents have been tried, none successful Hyaluronate-based membrane shown to reduce severity of adhesion formation (Becker, 1996; Vrigland, 2002) No studies yet to show reduction in obstruction
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Special Considerations: Recurrent Adhesions
So far, best evidence to prevent adhesions is good surgical technique: Gentle handling of bowel Avoid unnecessary dissection Exclusion of foreign material from peritoneum Adequate irrigation / removal of debris Place omentum around site of surgery
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Special Considerations: Acute Post-op Obstruction
Obstructive symptoms after an initial return of bowel function and resumption of oral intake Technical complication versus adhesions CT scan useful to evaluate for complications: Anastamotic leak Narrow anastomosis Internal hernia Obstruction at stoma Early reoperation may be indicated
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Acute Adhesive Postoperative Obstruction
Difficult to distinguish from ileus Incidence 0.7% Highest incidence on small intestine (3% – 10%) Present as early as POD 4 Usually partial SBO CT preferred modality
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Acute Postoperative Obstruction (Adhesive)
80% spontaneous resolution of symptoms 4% of patients required more than 2 weeks of treatment SBO after laparoscopy: suspect hernia at trocar site
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Surgery for Malignant Bowel Obstruction in Advanced Gynaecological and Gastrointestinal Cancer
Cochrane Review:2004 Role of surgery controversial No firm conclusions from many retrospective case series Control of symptoms varies from 42% to over 80 Rates of re-obstruction, from 10-50%, though time to re-obstruction was often not included Continues to be a challenging problem
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Steroids in Advanced Gyne/GI Cancer With SBO
Cochrane Review of prospective data (89 patients) Trend, not statistically significant, for resolution of bowel obstruction using corticosteroids No statistically significant difference in mortality NNT 6 Morbidity associated with steroids appears low
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Guidelines for Operative and Nonoperative Therapy
Summary Guidelines for Operative and Nonoperative Therapy
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Emergent Operation Incarcerated, strangulated hernia Peritonitis
Pneumatosis Pneumoperitoneum Suspected / proven strangulation Closed-loop obstruction Complete bowel obstruction
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Urgent Operation Progressive bowel obstruction after conservative measures started Failure to improve with conservative therapy in hours Early post-op technical complications (not adhesions)
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Operation Usually Delayed Safely
Postoperative adhesions Immediate post-op obstruction (adhesive) Acute exacerbation of Crohn’s dx, diverticulitis, radiation enteritis Chronic, recurrent partial obstruction
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Large Bowel Obstruction
Cancer Cancer (>90%) Other things Sigmoid Volvulus (5%) Diverticular Disease (3%)
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Large Bowel Obstruction
Approach Contrast Enema CT Abdo Treat underlying cause
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Acute Pseudo-Obstruction
Common ward consult Predisposing Conditions: Surgery Trauma Infection Cardiac (CHF/MI) Neurological (PD, SCI, MS, AD Metabolic (↓K/Na)
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Ogilvie’s Syndrome Meds Assoc w/Ogilvie’s Narcotics Anticholinergic
TCA Chlorpromazine Levodop Ca++ blockers Clonidine Ogilvie’s Initial Tx: Correct fluid and lyte NPO/NG Rectal tube Limit offending medications >80% success
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Ogilvie’s Treatment Neostigmine 2 mg IV Atropine at bedside
Monitored bed Patient supine, on bedpan 90% success rate Colonoscopy If neostigmine fails Decompression Surgery Last resort; rarely needed If ischemia/perforation
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