Presentation on theme: "Diagnosis of Acute Appendicitis"— Presentation transcript:
1 Diagnosis of Acute Appendicitis Jim Holliman, M.D., F.A.C.E.P.Professor of Military and Emergency MedicineUniformed Services University of the Health SciencesClinical Professor of Emergency MedicineGeorge Washington UniversityBethesda, Maryland, USA
2 ObjectivesTo review the pathophysiology and clinical presentation of acute appendicitisTo understand which patient groups are at high risk of misdiagnosisTo discuss the use of laboratory and imaging studies in the diagnosis of acute appendicitis
3 Appendicitis Incidence & Complications 6 % lifetime incidence69 % are ages 10 to 30Up to 30 % misdiagnosed initially20 to 30 % ruptured at surgeryMortality : 0.1 to 0.2 % unruptured, 3 to 5 % rupturedSignificant morbidity
4 Anatomic Aspects Blind pouch off of cecum Contains lymphoid tissue which peaks in adolescence, atrophies with ageFunction still unclearAppendix can be anywhere within peritoneal cavityOne study showed 65 % retrocecal, 31 % pelvicReview of 70,000 cases showed 4 % in RUQ, 0.06 % LUQ, 0.04 % LLQ
6 Pathophysiology of Appendicitis Lymphoid hyperplasia leads to luminal obstructionOften follows viral illnessEpithelial cells secrete mucusAppendix distends, bacteria multiplyVisceral pain begins an average of 17 hours after obstructionIncreased pressure compromises blood supplySomatic pain developsAverage time to perforation = 34 hrs.
7 Classic Presentation Seen in 60 % Anorexia and pain are most frequent Periumbilical pain, nausea, vomitingRLQ pain developing over 24 hrs.Anorexia and pain are most frequentUsually nausea, sometimes vomitingDiarrhea, esp. with pelvic locationUsually tender to palpationRebound is a later finding
9 Physical Exam Tenderness at McBurney's point Cutaneous hyperesthesia in T 10 to 12 dermatomesRovsing's signPsoas signObturator sign
10 MANTRELS Score Established in 1986 Migration of pain Anorexia Nausea / vomitingTenderness RLQReboundElevated temp.LeukocytosisShift to left
11 MANTRELS Score, cont'd.RLQ tenderness and leukocytosis = 2 points each ; all others 1 pointScore of 5 to 6 = possible appendicitisScore of 7 to 8 = probable appendicitisScore of 9 to 10 = very probable appendicitis
12 High Risk Patients Ovulating women PID, TOA, ovarian cyst rupture can mimic appendicitisLook for cervical motion tenderness, adnexal tenderness, history of STD’sCan have CMT with pelvic appendix
13 High Risk Patients, cont'd. PregnancyMost common surgical emergency in pregnancyMortality rate if missed = 2 % for mother, up to 35 % for fetusWBC elevated in pregnancyAppendix changes location
14 High Risk Patients, cont'd. PediatricsMost common surgical disorder in kidsAccounts for 5 % of abd. pain visitsUp to 50 % initially misdiagnosed< 2 yrs. : perforation rate approaches 100 %3 to 5 yrs. = 71 %6 to 10 yrs. = 40 %Most common misdiagnosis is AGESequence of pain and vomiting may be helpfulLocalized tenderness not a feature of AGE
15 High Risk Patients, cont'd. ElderlyVital signs and exam may not reflect severity> age 60 : only 5 to 10 % diagnosed without delayPerforation rate = 46 to 83 %RLQ tenderness absent in 23 %N/V, anorexia less commonLeukocytosis less pronouncedOnly 20 % classic presentation
16 High Risk Patients, cont'd. ImmunocompromisedHIV, chronic steroids, sickle cell, chemotherapy, DM, dialysisIncreased risk of complications and misdiagnosisInflammatory response decreased
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 nonspecificWBC normal in 80 % in the first 24 hrs.Can see elevated ANC in up to 89 %WBC usually 12 to 18,000 in appendicitisChemistry panelMay help with diagnosis of dehydration
20 Laboratory Studies, cont'd. UrinalysisSpecific gravity, ketonesCan see WBC’s, RBC’s, bacteria if inflamed appendix close to ureter> 30 WBC’s = probable UTIHCGEssential in women of child-bearing ageCRPAcute 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 % specificNoninvasive, low cost, but operator-dependentGood for diagnosing GYN disorders3 criteria for diagnosisTender, noncompressible appendixNo peristalsis of appendixOverall diameter > 6 mm
23 Imaging Studies, cont'd. Ultrasound (US) Appendix may not be seen, due to obesity, guarding, bowel gas, perforation, retrocecal location2.4 to 56 % of normal appendixes seenOne 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 accurateSensitivity 97 to 100 %, specificity 95 % (similar no matter what type or whether contrast is used)Often shows alternative diagnosisMore expensive, radiation exposure
26 Imaging Studies, cont'd. CT Criteria for appendicitis : Diameter > 6 mmFailure to completely fill with contrast or airAppendicolithWall thickening or enhancementOther 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 rateAnother 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 conflictingPediatric Imaging -Evidence-Based GuidelinesImaging most useful in clinically equivocal casesCosts of imaging minor compared to cost of unnecessary surgery or delayed diagnosisUS 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 Austria350 patients divided into low, intermediate, and high probabilityAll had US10 % of low prob., 24 % of intermediate prob., and 65 % of high prob. had appendicitisSpecificity 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. 2003Patients with classic presentation should go to O.R. Diagnostic accuracy approaches 95 %If equivocal or suspect perforation : CTUS reserved for pregnant women or high suspicion of GYN diseaseIf 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 studyAdults with abd. pain got up to 15 mg morphine vs. placeboIncreased pain relief, with no change in diagnostic accuracyNot all surgeons read their own literature, so give them a chance to come in a reasonable time frame or give the meds
34 Risk ManagementMisdiagnosis of appendicitis = 5th leading cause of successful litigation against EPs7 features of misdiagnosed cases :No nausea / vomitingLack of distressNo reboundNo guardingNo rectal exam (controversial)Narcotic pain meds givenDiagnosis of acute gastroenteritis
35 Risk Management, cont'd.When discharging, stress unclear diagnosis, what to watch forFollow up in 12 hours (PMD or E.D.)Can always observe if unsure"When in doubt, don't send them out."
36 SummaryAppendicitis is a common surgical emergency with a varied clinical presentationSeveral patient groups are at high risk of misdiagnosisLab and imaging studies are helpful, but no single study is a substitute for good clinical judgement