Appendicitis.pre

7/30/2019 Appendicitis.pre

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Diagnosis of AcuteAppendicitis

Jim Holliman, M.D., F.A.C.E.P.

Professor of Military and Emergency MedicineUniformed Services University of the Health Sciences

Clinical Professor of Emergency Medicine

George Washington University

Bethesda, Maryland, USA


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Objectives

To review the pathophysiology and

clinical presentation of acute

appendicitisTo understand which patient groups are

at high risk of misdiagnosis

To discuss the use of laboratory andimaging studies in the diagnosis of

acute appendicitis


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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

% rupturedSignificant morbidity


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Anatomic Aspects

Blind pouch off of cecum

Contains lymphoid tissue which peaks in

adolescence, atrophies with ageFunction 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


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Pathophysiology of Appendicitis

Lymphoid hyperplasia leads to luminal

obstruction

Often follows viral illnessEpithelial 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.


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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 vomitingDiarrhea, esp. with pelvic location

Usually tender to palpation

Rebound is a later finding


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Physical Exam

Tenderness at McBurney's point

Cutaneous hyperesthesia in T 10 to 12

dermatomesRovsing's sign

Psoas sign

Obturator sign


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MANTRELS Score

Established in 1986

Migration of pain

AnorexiaNausea / vomiting

Tenderness RLQ

ReboundElevated temp.

Leukocytosis

Shift to left


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MANTRELS Score, cont'd.

RLQ tenderness and leukocytosis = 2

points each ; all others 1 point

Score of 5 to 6 = possible appendicitisScore of 7 to 8 = probable appendicitis

Score of 9 to 10 = very probable

appendicitis


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High Risk Patients

Ovulating women

PID, TOA, ovarian cyst rupture can mimic

appendicitisLook for cervical motion tenderness,

adnexal tenderness, history of STDs

Can have CMT with pelvic appendix


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High Risk Patients, cont'd.

Pregnancy

Most common surgical emergency in

pregnancyMortality rate if missed = 2 % for mother,

up to 35 % for fetus

WBC elevated in pregnancy

Appendix changes location


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Pediatrics

Most common surgical disorder in kids

Accounts 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 AGE

Sequence of pain and vomiting may be helpful

Localized tenderness not a feature of AGE


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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


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Immunocompromised

HIV, chronic steroids, sickle cell,

chemotherapy, DM, dialysisIncreased risk of complications and

misdiagnosis

Inflammatory response decreased


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Differential Diagnosis

Gastroenteritis

Mesenteric

lymphadenitisPID

Mittelschmertz

Crohn's diseaseDiverticulitis

Endometriosis

TOA

Ectopic pregnancy

UTI

Pyelonepritis

Other processes

involving appendix


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" No single evaluation cansubstitute for the diagnostic

accuracy of the experienced

physician."


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Laboratory Studies

CBC

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 appendicitis

Chemistry panel

May help with diagnosis of dehydration


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Laboratory Studies, cont'd.

Urinalysis

Specific gravity, ketones

Can see WBCs, RBCs, bacteria ifinflamed appendix close to ureter

> 30 WBCs = probable UTI

HCGEssential in women of child-bearing age

CRP

Acute phase reactant


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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


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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


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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


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Ultrasound

Study from Australia showed total WBC

and neutrophil count were more accuratethan 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 onlyin pregnancy).


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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 diagnosis

More expensive, radiation exposure


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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


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CT

One study showed negative laparotomy

rates of 4 % in men, 8 % in ovulatingwomen with CT (typical is 20 % and 45 %

respectively), but no change in perforation

rate

Another study showed increase in CT useled to earlier diagnosis, less severe

pathologic findings, and decreased length

of stay


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CT

Study from Dept. of Surgery, Stamford,

Connecticut : use of CT markedlyincreased from 1994 to 2000, without

change in rate of negative appendectomy.

They concluded use of CT by

nonsurgeons leads to increased E.D. LOSwithout improving accuracy. They

recommend mandatory surgical consult if

CT considered.


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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 delayeddiagnosis

US and CT both specific enough to rule in

appendicitis, but only CT sensitive

enough to rule it out


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Study from Austria

350 patients divided into low,

intermediate, and high probabilityAll 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


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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


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Analgesia

Sir Zachary Cope's 1921 textbook of

surgery said no way

Prospective studies (both EM andSurgery literature) now show

appropriate use of IV narcotics does not

decrease diagnostic accuracy, and may

improve exam


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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. 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


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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 reboundNo guarding

No rectal exam (controversial)

Narcotic pain meds given

Diagnosis of acute gastroenteritis


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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."


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Summary

Appendicitis is a common surgical

emergency with a varied clinical

presentationSeveral patient groups are at high risk of

misdiagnosis

Lab and imaging studies are helpful, butno single study is a substitute for good

clinical judgement

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