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

6. 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.

7. Classic Presentation Seen in 60 % Anorexia and pain are most frequent
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

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

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

11. 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

12. 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

13. 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

14. 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

15. 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

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

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

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

19. Laboratory Studies CBC Chemistry panel
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

20. 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

21. 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

22. 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

23. 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

24. 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).

25. 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

26. 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

27. 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

28. 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.

29. 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

30. 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

31. 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

32. 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

33. 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

34. 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

35. 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."

36. 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