Disorders of Small & Large Bowel (Specially dedicated to Mark Wahba -- hope this helps buddy)

1. Disorders of Small & Large Bowel(Specially dedicated to Mark Wahba -- hope this helps buddy) Moritz Haager April 01, 2004

2. Outline • Appendicitis • Useful & useless tests • Mesenteric Ischemia • When to suspect it & how to chase it • Diverticular disease • Who has it? Whom to Tx & how.

3. Case 1 • 25 yo female c/o right lower quadrant pain. • What is your differential diagnosis? • How does you DDx change if she is 5 yo? 85 yo? Male? • Which historical & physical exam features are helpful in narrowing it down? • What lab & DI tests are useful? • Who can go home, who should stay, who needs to go to the OR?

4. Appendicitis Fast Facts • Incidence 1/1000 • Lifetime risk 6% -- genetic predisposition • Mortality 0.1% (20-60x higher in perf’d) • Initially misdiagnosed in 30% • Accepted negative laparotomy rate 20-25% • Perforation rate 20% • 70% in <9 yo or > 60 yo

5. True or False? • Appendicitis can occur at any age • T: most common in 10-30 yo • Appendicitis can present w/ LUQ pain • T: rare but possible (0.06%) • Appendicitis does not recur • F: estimated to recur in 6% • Definite gastroenteritis rules out appendicitis • F: viral & other infections can actually cause appendicitis due to lymphoid hypertrophy

6. Gastroenteritis Crohn’s Testicular torsion Meckel’s diverticulum Diverticulitis Mesenteric adenitis Cholelithiasis Pancreatitis Bowel obstruction Pelvic inflammatory disease Endometriosis Ovarian cyst Tubo-ovarian abscess Ectopic pregnancy Mittelschmerz Pyelonephritis Urinary Tract infection Appendicitis DDx

7. History & Physical • Aim to differentiate pts into 3 groups • High suspicion for appendicitis – need for immediate surgery • i.e. classic presentation • Intermediate suspicion for appendicitis – no clear-cut need to go to OR yet • Atypical presentation • Low suspicion for appendicitis

8. Diagnostic Strategies The only absolutely lab necessary test • Hx & P/E • Labs: CBC & diff, CRP, β-HCG, U/A, etc • Radiography • Plain films • Ultrasound • CT • Observation & serial examination • Laparoscopy

9. Classical Presentation • Good story: Pain starts as vague peri-umbillical discomfort  localizes to RLQ as sharp pin-point pain • WBC > 10 • Rebound & guarding at McBurney’s Point • Associated N & V, anorexia • Fever • Present within 48 hrs of onset • Occurs in only 50-60% of patients

10. If you didn’t know & were to embarrassed to ask • Psoas sign • With pt supine, get pt to flex hip against resistance by pushing down against knee -- pain = +ve • Obturator sign • Passively flex hip & knee and internally rotate leg at the hip -- pain = +ve • Rosvings sign • press down in LLQ then release suddenly -- pain = + ve

11. Symptoms Abd pain 97-100% Anorexia 70-92% Nausea 67-78% Vomiting 49-74% RLQ migration 49-61% Fever 10-20% Diarrhea 4-16% Constipation 4-16% RLQ pain LR+ 8.0; LR- 0.2 Rigidity LR+ 4.0; LR-0.82 Migration LR+ 3.1; LR- 0.5 Previous similar pain LR- 0.3 Signs Abd tenderness 95-100% RLQ tenderness 90-95% Rebound 33-68% Rectal tenderness 30-40% Cervical motion tenderness 30% Rigidity 12% Psoas sign3-5% Obturator sign 5-8% Rosvings sign 5% Palpable mass <5% Avg Temp 37.9oC Signs & Symptoms Wagner et al. Does this patient have appendicitis? JAMA 1996; 276: 1589-94

12. Accuracy of clinical findings Wagner et al. Does this patient have appendicitis? JAMA 1996; 276: 1589-94 * based on only one study

13. Do you need to do a Rectal? • NO • Sens 41%, Spec 77% • LR+ 0.83 - 5.34 • LR- 0.36 - 1.15 • Wagner et al. Does this patient have appendicitis? JAMA 1996; 276: 1589-94 • “Pain on rectal palpation has no discriminatory or predictive power” • Andersson. Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Brit J Surg. 2004; 91: 28-37

14. Utility of the WBC count • Elevated in 70-90% of pts w/ appendicitis • Somewhat helpful if >19 or <7 but this happens in only ~20% of pts • Snyder & Hayden. Accuracy of leukocyte count in diagnosis of acute appendicitis. Ann Emerg Med. 1999; 33: 565-574 • Very non-specific – many of the other disorders on the DDx will have elevated white count

15. Andersson. Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Brit J Surg. 2004; 91: 28-37 • No clinical or laboratory parameter alone found to have sufficient discriminatory or predictive capacity • Performance increased considerably when 2 or more variables were combined • Most useful variables were clinical markers of peritonitis, pain migration, and WBC & diff combined w/ CRP • Caveat: highly selected population of pts w/ suspected appendicitis admitted for further evaluation

16. Radiography • Plain films • 0% sensitivity for appendicitis– a waste of time if appy is your 1st thought • Ultrasound • Sensitivity 75-90%, Specificity 86-100% • Able to identify alternate diagnoses esp. in female pts • CT • Sensitivity 90-100%, specificity 91-99% • Able to identify alternate diagnoses

17. Ultrasound (Graded Compression) • Test Characteristics • Sensitivity 75-90%, Specificity 86-100% • Pros • No radiation, safe in kids, pregnant pts • Can identify alternate Dx esp. in female pts • Cons • Difficult for us to get locally • Operator-dependant • Limited in obese pts or ++ bowel gas • Identifies alternate Dx less often than CT • Painful

18. CT • Test characteristics • Sensitivity 90-100%, specificity 91-99% • Pros • Identifies alternate Dx more often than U/S • Fast & accessible in our practice setting • Cons • Radiation dose (~100 CXR’s) • Multiple techniques in literature: controversial as to which is best but all ~90-100% sensitive • Spiral vs. conventional • Focused vs. entire abdomen • Unenhanced, various combinations of IV, oral, rectal contrast • Less accurate in pts w/ little intraabdominal fat

19. Which test is better? • 2 prospective RCT’s of U/S vs. CT • CT more sensitive & specific than U/S • 94-97% sensitive vs. 76 – 100% for U/S • 100% specificity vs. 76-90% for U/S • More alternate Dx identified by CT • Horton et al. Am J Surg 2000; 179: 379-81 • Walker et al. Am J Surg 2000; 180: 450-55

20. Which test is better? • 120 consecutive pts 8-81 yo w/ ?appy who were to well to go to OR but too ill to simply D/C • Did focused CT w/ rectal contrast & U/S within 1 hr on all pts • Gold standard was pathology or clinical f/u x 6 mo • CT: 95% sensitive, 89% specific • U/S: 87% sensitive, 74% specific • CT identified 14 alternate Dx vs. 9 for U/S • U/S missed 2/3 of pts w/ perforation • Pickuth et al. Suspected acute appendicitis: Is ultrasonography or computed tomography the preferred imaging technique? Eur J Surg. 2000; 166: 315-19

21. Does imaging change mgmt? • 2 studies of CT in pts w/ suspected appendicitis comparing Tx plan before & after access to results of scans • CT changed disposition in 27 – 59% of pts • Prevented d/c of ~3% pts w/ appendicitis • Prevented negative laparotomy in 3-13% • Alternate Dx in 11-20% • Frank et al. Unenhanced helical CT scanning of the abdomen and pelvis changes disposition of patients presenting to the emergency department with possible acute appendicitis. J Emerg Med 2002; 23: 1-7 • Rao et al. Effect of computed tomography of the appendix on treatment of patients and use of hospital resources. N Eng J Med. 1998; 338: 141-6

22. Bottom-line • Pts w/ high pre-test probability should go for appendectomy regardless of imaging result • Pts w/ very low pre-test probability should be clearly instructed when to return for re-evaluation • Pts who fall in b/w these extremes benefit most from imaging

23. Bottom-line • Both are good but if I had only one test I’d take the CT • If I had only 5 CT’s or U/S’s available per month I’d use them on women rather than men • If I had a very skinny pt, pregnant pt, or kid I’d prefer to do a U/S • If I thought the main DDx was gastro vs. appy I’d be happy w/ a focused CT …. • …but if I had the sense this pt has something going on which could be appy but I’m really not sure I’d want the entire belly CT preferably with contrast

24. Observation & Serial exams • Reasonable alternative but not well studied • Pro • Observation for 6-10 hrs in intermediate-risk pts does not appear to increase risk of perforation while potentially lowering negative appy rate • Con • In kids perforation is the rule – delays may increase complications • Cost of admission may outweigh cost of DI • If observed in the department can slow flow

25. Proposed Appy Algorithm Paulson et al. Suspected appendicitis. N Eng J Med 2003; 348: 236-42

26. Case 2 • 61 yo female with severe acute abdominal pain for 3 hrs. Has vomited and had 3 watery stools. • Afebrile, no evidence of peritonitis • PMHx remarkable for rheumatic fever & HTN.

27. Mesenteric Ischemia • Simply stated this is blocked or restricted blood flow to the gut • Pathophysiology essentially same as that for CAD & thromboembolic cardiovascular dz • 4 major types w/ different Tx & prognosis • Occlusive (80%) • Arterial • Embolic (50%) • Thrombotic (15%) • Venous • Thrombotic (15%) • Non-occlusive (20%) • Low flow states e.g. sepsis, hypovolemia  “shock bowel”

28. Anatomy • Celiac Trunk • Pharynx, esophagus, stomach, proximal duodenum, liver, GB, pancreas, spleen • SMA • Distal duodenum, jejunum, ileum, cecum, ascending colon, 2/3 transverse colon • IMA • Distal 1/3 transverse colon, descending & sigmoid colon, rectum • Extensive collateral supply & overlap exist b/w these = protective to a large degree • Venous system parallels arterial system

29. Clinical Presentation • Triad of acute abdo pain, diarrhea, & vomiting in high risk pt • Very non-specific especially early when its critical to make the Dx – broad DDx • ‘Time is gut” & dead gut frequently = dead pt • Peritoneal signs = transmural necrosis • 70-90% mortality untreated • 45-50% mortality treated w/ peritonitis • ~10% mortality if early Dx (no peritonitis) • Most useful S & S: • Visceral pain out of proportion to exam • Dull, not worse w/ movement or palpation • Older & Risk factors for atherosclerotic +/- embolic dz

30. Mesenteric arterial embolic Dz • Vast majority involve SMA (45o angle) • Better prognosis than thrombosis • Emboli lodge at distal branch points rather than origin  smaller area of gut involved • Tend to present earlier w/ more typical Sx • Better response to Tx • Risk Factors • Older, CAD, Post-MI (mural thrombi), CHF, a fib, valvular Dz, aortic dissection / aneurysm, aortic surgery, angiography, Hx of thromboembolic Dz

31. Mesenteric arterial thrombosis • Occurs in more proximal vessel origin  worse prognosis • SMA again most common site • Analogous to CAD: angina & MI • May have Hx of abdominal angina • Strong association w/ CAD

32. Mesenteric venous thrombosis • Younger pts (can occur any age) • Less mortality (20 – 50%) • 95% of all cases involve SMV • Risk factors • Hypercoagulable state • Polycythemia vera, myeloproliferative Dz, ATIII deficiency, protein C & S deficiency, DVT, malignancy, estrogen Tx, pregnancy, sickle cell • Intraabdominal inflammation • Pancreatitis, diverticulitis, appendicitis, cholangitis • Trauma • Other • CHF, renal failure, the bends, portal HTN

33. Non-occlusive mesenteric ischemia • Due to mesenteric vasoconstriction or low-flow state secondary to other critical illness • CVS • CHF, MI, Post CABG, • Shock states • Septic, hypovolemic, cardiogenic etc • Drugs • Inotropes, cocaine, ergots, digoxin

34. Diagnostic Strategies • History & physical • Labs • WBC, lactate, CK • Diagnostic Imaging • Plain films • CT • U/S • Angiography

35. Utility of lab tests • WBC • Elevated in most but decreased sensitivity early, & very non-specific • CK • 54% sens at 2 hrs, 75% sens at 4 hrs, 83% spec • Lactate • Up to 96- 100% sensitive, 42% specific (at what time point) • ? α-Glutathione S-transferase • Promising but limited studies at the moment • Paucity of good studies on markers • Generally too insensitive & non-specific

36. Plain films • Only 28-30% sensitive • Many non-specific findings.. • Ileus, free air, obstruction • …or specific findings (too) late • Pneumatosis intestinalis, portal venous gas, thickened bowel wall, thumbprinting • Too insensitive & nonspecific to aid in early Dx

37. CT • Sens 64-82% • Look for evidence of ischemia in bowel wall & mesentary • Evidence of clot in SMA • First investigation done routinely here • If suspecting mesenteric ischemia very important to let your radiologist know • Good but not good enough • If CT is negative & high pre-test probability you need an angiogram

38. Ultrasound • Doppler can determine major obstruction to flow in both venous & arterial systems • See dilated, tubular vessels full of echogenic material (clot) and abnormal flow • Limitations • Used & studied primarily in venous thrombosis & chronic mesenteric ischemia • Really don’t know much about how it performs for acute mesenteric ischemia • Only good for more proximal blockages • Has the usual limitations inherent to all U/S exams

39. Angiography • Gold standard test (~90% sens) • Diagnostic & therapeutic • Infusions of vasodilators into SMA (papaverine) • Angioplasty • Controversies: • When & on whom to do it • Drawbacks • Time-consuming • Risks of contrast & invasive procedure • Expensive

40. Angiography: Early vs. late strategy • Most authors feel angiography should be done early in pts w/o peritonitis & high suspicion • Can buy time (papaverine) • Can aid in surgical decision making • Surgical: embolectomy, thrombectomy, endarterectomy, bypass grafting • Non-surgical: angioplasty • Early (before peritonitis) angiography & intervention decreased mortality from 70-90% to 10% in several studies • Down side is high rate of negative angios & associated risks & costs

41. Angiography: When not to do it • Contraindicated in: • Unstable hypotensive pts on vasopressors • Difficult to differentiate b/w occlusive & non-occlusive etiologies • Can’t infuse vasodilators • Pts w/ peritonitis • Delays surgery

42. MRI • Gadolinium-enhanced MRA appears to be very good • MRI best at differentiating potentially viable from dead gut • Currently limited by length of acquisition time & cost but will likely play larger role in the future

43. ED management • ABC’s • Maintain CO • Maximize oxygenation • IV Antibiotics • Broad spectrum (amp, gent, flagyl) • Glucagon? • Increases splanchnic blood flow • Effective in animal models but no evidence in humans • Get radiology & surgery involved early • Restore flow (papaverine, angioplasty, thrombolytics, surgery) • Resect dead gut & anticoagulate post-op

44. Papaverine • Vasodilator • Phosphodiesterase inhibitor – increases cAMP which causes smooth muscle relaxation • Given as intraarterial infusion into SMA • No – minimal systemic effects as 90% 1st pass metabolism in liver • 60 mg bolus, then 30-60 mg/h infusion • Good for occlusive & non-occlusive etiologies • Improves survival by 20-50%

45. Case • 75 yo male c/o worsening LLQ pain x 2/7 • Febrile 39.1o, WBC 19,000 • Voluntary guarding LLQ

46. Diverticular disease • Diverticulosis • Pseudodiverticula • Outpouchings of mucosa & submucosa through muscular wall at weakest points (vasa recta) • Sigmoid > than R colon • Western populations >> developing countries • Unclear pathophysiology but related to low fiber diet & advanced age • 50-60 yo – 30% have it • 70 yo – 50% • 85 yo – 66%

47. Diverticular disease • Diverticulosis • 85% will remain asymptomatic • 15% will develop symptoms • ~11% develop painful diverticulosis • IBS-like Sx: abdo pain, bloating, diarrhea and/or constipation • Precise mechanism of pain remains unclear ? low-grade inflammation  neuro-muscular dysfunction & spasm • ~4% go on to develop diverticulitis • 1-2 % require admission & ~0.5% will require surgery

48. Diverticulitis • Inflammation & infection of diverticula • Triad of LLQ pain, fever, leukocytosis • Pathogenesis unclear -- ?obstruction of diverticula (mechanism similar to appendicitis) • 3 types • Asymptomatic • Acute diverticulitis • Complicated diverticulitis • Obstruction, bleeding, perforation

49. Diagnostic Strategies • Hx & physical • Labs • WBC • Radiology • Plain films • CT • Water-soluble contrast enema • Barium enema • Endoscopy

50. Plain films • Not sensitive or specific for diverticular disease • Primary utility in ruling out obstruction or perforation