1. Abdominal Pain and Bowel Obstruction
Mike Goodwin
CRASH Course
October, 2010

2. Abdominal Pain - Approach
History
Physical
Labs
Imaging
Provisional Dx

3. History
PQRST AAA etx
But don’t forget
PSx
Bowel/Gyne/Urol ROS

7. Physical Exam Complete General appearance/vitals/H+N/Chest Abdo:
Rigidity
Rebound
Guarding
IPPA
DRE / Pelvic / Groin / Flank-CVA

8. Labs Everyone: CBC, lytes BUN Cr LFT, Bili, Amylase/Lipase, lactate
Urinalysis
Urine Preg

9. 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

10. Imaging CT Abdo Test of choice for most patients
Protocols to minimize contrast nephropathy

11. Bowel Obstruction: Overview
History
Etiology
Pathophysiology
Clinical presentation
Imaging
Management
Special considerations

12. Causes of Small Bowel Obstruction in Adults
Lesions Extrinsic to the Intestinal Wall   
Lesions Intrinsic to the Intestinal Wall   
Intraluminal/Obturator Obstruction   

13. 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

14. 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

15. Intraluminal/Obturator Obstruction
Gallstone   
Enterolith   
Bezoar

16. Common causes of small bowel obstruction in industrialized countries.

17. Pathophysiology Early: Increased motility & contractility
Bowel dilation, fluid/lytes accumulate in lumen and bowel wall
Third spacing, intravascular volume depletion

18. Bowel obstruction
Increased intraluminal pressure
Decreased mucosal blood flow
Progressive Ischemia
Perforation & Peritonitis

19. Clinical Diagnosis History Colicky abdominal pain Nausea / vomiting
Abdominal distension
Failure to pass flatus / feces

20. 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

21. Radiology Plain Abdo X-Rays Confirm Diagnosis
Localize obstruction to small bowel or colon
Evidence of complete or incomplete

22. 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.)

23. *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

24. 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

25. AXR Disadvantages 20-30% false negative rate
Does not localize site of obstruction
Does not establish etiology of obstruction

26. 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)

27. 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.

28. 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

29. 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

30. 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

31. 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).

32. 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

33. B, A patient with strangulated obstruction, evidence of which includes bowel wall thickening (blue arrow), mesenteric stranding (green arrow), and ascites (asterisk).

34. 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

35. Barium / Contrast Studies
History of recurring obstruction
Low-grade mechanical obstruction
Defines the obstructed segment and degree of obstruction

36. 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

37. Simple Versus Strangulating Obstruction
Classic signs:
Fever
WBC inc
Constant Abdo pain
But no parameters reliably detect strang.
CT findings detect late ischemic changes

38. 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

40. 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

41. 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

42. 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

43. Laparoscopy in Acute SBO?
Criteria:
Mild distension
Proximal obstruction
Partial obstruction
Anticipated single-band obstruction
No matted adhesions / carcinomatosis

44. 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

45. 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

46. 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

47. 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

48. 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

49. 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

50. 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

51. Guidelines for Operative and Nonoperative Therapy
Summary
Guidelines for Operative and Nonoperative Therapy

52. Emergent Operation Incarcerated, strangulated hernia Peritonitis
Pneumatosis
Pneumoperitoneum
Suspected / proven strangulation
Closed-loop obstruction
Complete bowel obstruction

53. Urgent Operation
Progressive bowel obstruction after conservative measures started
Failure to improve with conservative therapy in hours
Early post-op technical complications (not adhesions)

54. Operation Usually Delayed Safely
Postoperative adhesions
Immediate post-op obstruction (adhesive)
Acute exacerbation of Crohn’s dx, diverticulitis, radiation enteritis
Chronic, recurrent partial obstruction

55. Large Bowel Obstruction
Cancer
Cancer (>90%)
Other things
Sigmoid Volvulus (5%)
Diverticular Disease (3%)

56. Large Bowel Obstruction
Approach
Contrast Enema
CT Abdo
Treat underlying cause

57. Acute Pseudo-Obstruction
Common ward consult
Predisposing Conditions:
Surgery
Trauma
Infection
Cardiac (CHF/MI)
Neurological (PD, SCI, MS, AD
Metabolic (↓K/Na)

58. 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

59. 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