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Diagnosis of Acute Appendicitis

Diagnosis of Acute Appendicitis. Jim Holliman, M.D., F.A.C.E.P. Professor of Military and Emergency Medicine Uniformed Services University of the Health Sciences Clinical Professor of Emergency Medicine George Washington University Bethesda, Maryland, USA. Objectives.

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Diagnosis of Acute Appendicitis

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  1. Diagnosis of Acute Appendicitis Jim Holliman, M.D., F.A.C.E.P. Professor of Military and Emergency Medicine Uniformed Services University of the Health Sciences Clinical Professor of Emergency Medicine George Washington University Bethesda, Maryland, USA

  2. Objectives • To review the pathophysiology and clinical presentation of acute appendicitis • To understand which patient groups are at high risk of misdiagnosis • To discuss the use of laboratory and imaging studies in the diagnosis of acute appendicitis

  3. Appendicitis Incidence & Complications • 6 % lifetime incidence • 69 % are ages 10 to 30 • Up to 30 % misdiagnosed initially • 20 to 30 % ruptured at surgery • Mortality : 0.1 to 0.2 % unruptured, 3 to 5 % ruptured • Significant morbidity

  4. Anatomic Aspects • Blind pouch off of cecum • Contains lymphoid tissue which peaks in adolescence, atrophies with age • Function still unclear • Appendix can be anywhere within peritoneal cavity • One study showed 65 % retrocecal, 31 % pelvic • Review of 70,000 cases showed 4 % in RUQ, 0.06 % LUQ, 0.04 % LLQ

  5. Pathophysiology of Appendicitis • Lymphoid hyperplasia leads to luminal obstruction • Often follows viral illness • Epithelial cells secrete mucus • Appendix distends, bacteria multiply • Visceral pain begins an average of 17 hours after obstruction • Increased pressure compromises blood supply • Somatic pain develops • Average time to perforation = 34 hrs.

  6. Classic Presentation • Seen in 60 % • Anorexia • Periumbilical pain, nausea, vomiting • RLQ pain developing over 24 hrs. • Anorexia and pain are most frequent • Usually nausea, sometimes vomiting • Diarrhea, esp. with pelvic location • Usually tender to palpation • Rebound is a later finding

  7. Physical Exam • Tenderness at McBurney's point • Cutaneous hyperesthesia in T 10 to 12 dermatomes • Rovsing's sign • Psoas sign • Obturator sign

  8. MANTRELS Score • Established in 1986 • Migration of pain • Anorexia • Nausea / vomiting • Tenderness RLQ • Rebound • Elevated temp. • Leukocytosis • Shift to left

  9. MANTRELS Score, cont'd. • RLQ tenderness and leukocytosis = 2 points each ; all others 1 point • Score of 5 to 6 = possible appendicitis • Score of 7 to 8 = probable appendicitis • Score of 9 to 10 = very probable appendicitis

  10. High Risk Patients • Ovulating women • PID, TOA, ovarian cyst rupture can mimic appendicitis • Look for cervical motion tenderness, adnexal tenderness, history of STD’s • Can have CMT with pelvic appendix

  11. High Risk Patients, cont'd. • Pregnancy • Most common surgical emergency in pregnancy • Mortality rate if missed = 2 % for mother, up to 35 % for fetus • WBC elevated in pregnancy • Appendix changes location

  12. High Risk Patients, cont'd. • Pediatrics • Most common surgical disorder in kids • Accounts for 5 % of abd. pain visits • Up to 50 % initially misdiagnosed • < 2 yrs. : perforation rate approaches 100 % • 3 to 5 yrs. = 71 % • 6 to 10 yrs. = 40 % • Most common misdiagnosis is AGE • Sequence of pain and vomiting may be helpful • Localized tenderness not a feature of AGE

  13. High Risk Patients, cont'd. • Elderly • Vital signs and exam may not reflect severity • > age 60 : only 5 to 10 % diagnosed without delay • Perforation rate = 46 to 83 % • RLQ tenderness absent in 23 % • N/V, anorexia less common • Leukocytosis less pronounced • Only 20 % classic presentation

  14. High Risk Patients, cont'd. • Immunocompromised • HIV, chronic steroids, sickle cell, chemotherapy, DM, dialysis • Increased risk of complications and misdiagnosis • Inflammatory response decreased

  15. Differential Diagnosis • Gastroenteritis • Mesenteric lymphadenitis • PID • Mittelschmertz • Crohn's disease • Diverticulitis • Endometriosis • TOA • Ectopic pregnancy • UTI • Pyelonepritis • Other processes involving appendix

  16. " No single evaluation can substitute for the diagnostic accuracy of the experienced physician."

  17. Laboratory Studies • CBC • 75 to 85 % have elevated WBC, but it is nonspecific • WBC normal in 80 % in the first 24 hrs. • Can see elevated ANC in up to 89 % • WBC usually 12 to 18,000 in appendicitis • Chemistry panel • May help with diagnosis of dehydration

  18. Laboratory Studies, cont'd. • Urinalysis • Specific gravity, ketones • Can see WBC’s, RBC’s, bacteria if inflamed appendix close to ureter • > 30 WBC’s = probable UTI • HCG • Essential in women of child-bearing age • CRP • Acute phase reactant

  19. Imaging Studies • Plain films • Low sensitivity and specificity • Appendicolith specific, but seen in only 2 % • May see local air-fluid levels, psoas obliteration, soft tissue mass, gas in appendix : all nonspecific

  20. Imaging Studies, cont'd. • Ultrasound • 75 to 90 % sensitive, 86 to 100 % specific • Noninvasive, low cost, but operator-dependent • Good for diagnosing GYN disorders • 3 criteria for diagnosis • Tender, noncompressible appendix • No peristalsis of appendix • Overall diameter > 6 mm

  21. Imaging Studies, cont'd. • Ultrasound (US) • Appendix may not be seen, due to obesity, guarding, bowel gas, perforation, retrocecal location • 2.4 to 56 % of normal appendixes seen • One study of 736 pediatric patients showed 36.6 % without preop US had negative appendectomy vs. 9.8 % who had US

  22. Imaging Studies, cont'd. • Ultrasound • Study from Australia showed total WBC and neutrophil count were more accurate than US. They recommended pts. with unequivocal presentation go to OR. If equivocal, obtain CBC. If WBC > 15,000, go to OR. If < 11,000, obtain CT (US only in pregnancy).

  23. Imaging Studies, cont'd. • CT • Early studies showed low yield, but helical CT much more accurate • Sensitivity 97 to 100 %, specificity 95 % (similar no matter what type or whether contrast is used) • Often shows alternative diagnosis • More expensive, radiation exposure

  24. Imaging Studies, cont'd. • CT • Criteria for appendicitis : • Diameter > 6 mm • Failure to completely fill with contrast or air • Appendicolith • Wall thickening or enhancement • Other contributory signs include fat stranding, fluid, inflammatory mass, adenopathy

  25. Imaging Studies, cont'd. • CT • One study showed negative laparotomy rates of 4 % in men, 8 % in ovulating women with CT (typical is 20 % and 45 % respectively), but no change in perforation rate • Another study showed increase in CT use led to earlier diagnosis, less severe pathologic findings, and decreased length of stay

  26. Imaging Studies, cont'd. • CT • Study from Dept. of Surgery, Stamford, Connecticut : use of CT markedly increased from 1994 to 2000, without change in rate of negative appendectomy. They concluded use of CT by nonsurgeons leads to increased E.D. LOS without improving accuracy. They recommend mandatory surgical consult if CT considered.

  27. Do We Need Imaging Studies? • Literature conflicting • Pediatric Imaging -Evidence-Based Guidelines • Imaging most useful in clinically equivocal cases • Costs of imaging minor compared to cost of unnecessary surgery or delayed diagnosis • US and CT both specific enough to rule in appendicitis, but only CT sensitive enough to rule it out

  28. Do We Need Imaging Studies? • Study from Austria • 350 patients divided into low, intermediate, and high probability • All had US • 10 % of low prob., 24 % of intermediate prob., and 65 % of high prob. had appendicitis • Specificity and sensitivity of US = 98 % • Concluded imaging should be done even in high probability patients

  29. Do We Need Imaging Studies? • NEJM : Suspected Appendicitis Jan. 2003 • Patients with classic presentation should go to O.R. Diagnostic accuracy approaches 95 % • If equivocal or suspect perforation : CT • US reserved for pregnant women or high suspicion of GYN disease • If study indeterminate, observe with repeated exams or laparoscopy

  30. Analgesia • Sir Zachary Cope's 1921 textbook of surgery said no way • Prospective studies (both EM and Surgery literature) now show appropriate use of IV narcotics does not decrease diagnostic accuracy, and may improve exam

  31. Analgesia, cont'd. • Journal of American College of Surgeons : Jan. 2003 • Prospective, randomized, double blind study • Adults with abd. pain got up to 15 mg morphine vs. placebo • Increased pain relief, with no change in diagnostic accuracy • Not all surgeons read their own literature, so give them a chance to come in a reasonable time frame or give the meds

  32. Risk Management • Misdiagnosis of appendicitis = 5th leading cause of successful litigation against EPs • 7 features of misdiagnosed cases : • No nausea / vomiting • Lack of distress • No rebound • No guarding • No rectal exam (controversial) • Narcotic pain meds given • Diagnosis of acute gastroenteritis

  33. Risk Management, cont'd. • When discharging, stress unclear diagnosis, what to watch for • Follow up in 12 hours (PMD or E.D.) • Can always observe if unsure • "When in doubt, don't send them out."

  34. Summary • Appendicitis is a common surgical emergency with a varied clinical presentation • Several patient groups are at high risk of misdiagnosis • Lab and imaging studies are helpful, but no single study is a substitute for good clinical judgement

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