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
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
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
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
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.
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
Physical Exam
Tenderness
at McBurney's point
Cutaneous hyperesthesia in T 10 to 12
dermatomes
Rovsing's sign
Psoas sign
Obturator sign
MANTRELS Score
Established
in 1986
Migration of pain
Anorexia
Nausea / vomiting
Tenderness RLQ
Rebound
Elevated temp.
Leukocytosis
Shift to left
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
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
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
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 %
ƒ 3 to 5 yrs. = 71 %
ƒ 6 to 10 yrs. = 40 %
ƒ
Most common misdiagnosis is AGE
Sequence of pain and vomiting may be helpful
Localized tenderness not a feature of AGE
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
High Risk Patients, cont'd.
Immunocompromised
HIV, chronic steroids, sickle cell,
chemotherapy, DM, dialysis
Increased risk of complications and
misdiagnosis
Inflammatory response decreased
Differential Diagnosis
Gastroenteritis
TOA
Mesenteric
Ectopic
lymphadenitis
PID
Mittelschmertz
Crohn's disease
Diverticulitis
Endometriosis
UTI
pregnancy
Pyelonepritis
Other
processes
involving appendix
" No single evaluation can
substitute for the diagnostic
accuracy of the experienced
physician."
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
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
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
Imaging Studies, cont'd.
Ultrasound
75 to 90 % sensitive, 86 to 100 % specific
Noninvasive, low cost, but operatordependent
Good for diagnosing GYN disorders
3 criteria for diagnosis
ƒ Tender, noncompressible appendix
ƒ No peristalsis of appendix
ƒ Overall diameter > 6 mm
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
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).
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
Imaging Studies, cont'd.
CT
Criteria for appendicitis :
Diameter > 6 mm
ƒ Failure to completely fill with contrast or
air
ƒ Appendicolith
ƒ Wall thickening or enhancement
Other contributory signs include fat
stranding, fluid, inflammatory mass,
adenopathy
ƒ
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
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.
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
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
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
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
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
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
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."
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