Download Pediatric Blunt Abdominal Trauma

The Role of Diagnostic
Imaging in Appendicitis
D. Joseph Grunz, MD
Department of Radiology
Mercy Children’s Hospital- St. Louis
Objectives
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Discuss current topics and role of diagnostic
imaging for evaluation of appendicitis
Discuss controversies regarding specific imaging
techniques, especially regarding multi-detector
computed tomography and ultrasound
Discuss current preferences and imaging
strategies
CT vs. US
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Benefits of CT studies
Rapid evaluation
 High degree of diagnostic confidence
 High degree of reproducibility
 Evaluation of other etiologies
 Decreased negative laparotomy and perforation rates
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Downside of CT studies
Radiation concerns
 IV contrast usage
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CT vs. US
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Benefits of ultrasound
No use of radiation
 Evaluation of pelvic disease in girls
 Can localize to site of pain
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Downside of ultrasound
Not on site after hours
 Lower degree of diagnostic confidence
 Lower degree of reproducibility
 Limited evaluation of other etiologies
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CT Findings
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Normal appendix- blind ending tubular structure
with air
CT Findings
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Dilated tubular fluid structure with contrastenhancing walls, possible appendicolith
US Findings
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Normal appendix, compressible, less than 6 mm
in thickness
US Findings
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Abnormal appendix, non-compressible,
increased vascular flow, fluid-filled
Choosing Wisely
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American College of Radiology- Five Things Physicians and
Patients Should Question
 1. Don’t do imaging for uncomplicated headache.
 2. Don’t image for suspected pulmonary embolism (PE)
without moderate or high pre-test probability.
 3. Avoid admission or preoperative chest x-rays
 4. Don’t do computed tomography (CT) for the evaluation of
suspected appendicitis in children until after ultrasound has
been considered as an option.
 5. Don’t recommend follow-up imaging for clinically
inconsequential adnexal cysts.
ACR-Choosing Wisely
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Although CT is accurate in the evaluation of suspected
appendicitis in the pediatric population, ultrasound is
nearly as good in experienced hands. Since ultrasound
will reduce radiation exposure, ultrasound is the
preferred initial consideration for imaging examination
in children. If the results of the ultrasound exam are
equivocal, it may be followed by CT. This approach is
cost-effective, reduces potential radiation risks and has
excellent accuracy, with reported sensitivity and
specificity of 94 percent.
The way we were
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1981
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Computed tomography? It will never last!
1988
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R. Brooke Jeffrey- early US advocate
Goal was to reduce unnecessary laparotomy rates
 Establish criteria to exclude appendicitis
 Take home point- US appendix has been around a long
time.
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Are We Resistant to New
Technology?
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PACS technology
CT perfusion
CT 3D reformat
MR enterography
MR cholangiogram
US sonohysterography
CT angiography
CT urography
CT coronary artery
MR angiography
US pyloric channel
US musculoskeletal
Intussusception
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Standard of care was barium enema reduction
Intussusception
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Air insufflation enema adopted
Intussusception
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Ultrasound
Come and gone
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Intravenous pyelography
Plain film tomography
Herniography
Venography
CT colonoscopy
CT screening for cancer
Not yet or never were
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US gastro-esophageal reflux
US voiding cystourethrography
US malrotation/midgut volvulus
US intussusception reduction
US with IV contrast
It’s not over until …
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CT pulmonary angiogram vs. V/Q scan
Fluoroscopic voiding cystourethrogram vs.
nuclear medicine voiding cystourethrogram
CT angiography vs. MR angiography vs.
conventional angiography
MR lumbar spine vs. CT lumbar spine
myelography
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“When the facts change, I change my mind.
What do you do, sir?”
― John Maynard Keynes
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1999-2000 Increased reliance on CT for
diagnosis of pediatric appendicitis
95 % sensitivity, 94 % specificity
Alternate diagnosis in 34 %
USA Today 2001
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Children are exposed to unnecessary radiation
doses for CT studies.
Children are receiving adult radiation settings for
CT studies
CT studies should be calibrated for child
age/size
New England Journal of Medicine,
Nov. 2007
“The largest increases in CT use have been in the
categories of pediatric diagnosis and adult
screening.”
 “There is direct evidence from epidemiologic studies
that the organ doses corresponding to a common
CT study (two or three scans, resulting in a dose in
the range of 30 to 90 mSv) result in an increased risk
of cancer. The evidence is reasonably convincing for
adults and very convincing for children.”
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Children are at higher risk to
develop cancer because…
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Children are more radiosensitive
Children have a longer lifespan for cancer to
develop
Increased ED utilization 2000-2006
Public Awareness (?)
2011 Articles
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There has been significantly increased utilization
of CT scans in the pediatric emergency room
setting.
Based upon population studies, if 1.6 million CT
studies are performed, there is a theoretical risk
that 1,500 children will develop a fatal neoplasm
as a result
Did not conclude these exams were
unnecessary, but such was the implication
Back to Ultrasound Stats
Sweden (2002) Children
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US sensitivity 86%, specificity 95%
CT sensitivity 80%, specificity 97%
Prevalence of 41%
Negative predictive value of 92%
High sensitivity study- Kessler,
France (2004)
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125 patients, appendicitis prevalence of 46%
Appendix identified in 86% of patients
Appendix identified in 96% of patients with
appendicitis
Appendix identified in 72% of patients without
appendicitis
Negative predictive value of 90% if appendix
not visualized
Meta-analysis study (2006)
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US sensitivity 88%, specificity 94% for children
CT sensitivity 94%, specificity 95% for children
Our experience
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Matches CT experience of other institutions
Nowhere close to the ultrasound percentages for finding the
appendix, making the diagnosis, or excluding the diagnosis
"When you unwrap a Reggie bar, it tells
you how good it is." - Catfish Hunter
University of Michigan, Pediatric
Radiology, March 2012
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Observed their experience doesn’t correspond
as well as described in the literature
Identified the appendix 24% of the time.
What to do?
Understand the Issues for the ED
physicians
ED Issues
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Safe, reliable, available diagnostic exam for appendicitis is highly
desirable
Discharge home or admission for observation is frequently
undesirable
 Unstable social situation
 Long travel distance
 Rapid clinical deterioration
 Pain control
 Limited hospital beds
Malpractice issues
Risks of Appendicitis
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Most common acute abdominal condition
requiring childhood surgery
Commonly missed or delayed diagnosis
Complications include peritonitis, sepsis, bowel
obstruction, death
Second most common cause for litigation, and
one third of claims involve diagnostic error
Put risks into perspective
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Lifetime cancer risk is 44.00% for men, 38.00%
for women
Single CT scan for a child age five theoretically
increases that risk 00.02%
Physicians need to understand the risk/benefit
Risk of missed diagnosis is immediate and real
 Risk of radiation exposure is delayed and theoretical
 Eliminate unnecessary exams, not necessary exams
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Estimated Lifetime Risk of Death
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Lightning strike
Bicycle accident
Drowning
Motor vehicle accident
Cancer (natural causes)
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1 in 100,000
1 in 10,000
1 in 1,000
1 in 100
1 in 3-4
Cancer, pediatric (single
CT)
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1 in 3000-30,000
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Understand
institutional/population bias
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Patient population
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Prevalence of obesity
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Social/cultural conditions
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Time of presentation/need for follow-up
Age/gender of patients
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Relevant for US vs. CT
Younger children/adolescent females
Institution resources/support
My biases
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Awareness of cancer risks associated with
pediatric CT need to be raised
Alternatives to CT studies need to be explored
If there is a low pre-test probability, neither
ultrasound nor CT study is an appropriate
diagnostic imaging examination
If there is mid to high pre-test probability, and
it will likely change the course of treatment, CT
is the study of choice for appendicitis
Pre-test probability
My bias against ultrasound
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There is still controversy about this exam, decades after
introduction, even among highly qualified radiologists
The appendix is not found in ¾ of all examinations
When the appendix is not found, appendicitis can’t be
excluded
When the appendix is found and appendicitis suspected, there
is still a false positive rate of 25%
The immediate risk of patient harm from missed ultrasound
diagnosis is much more compelling than the theoretical risk
(and lower) long-term risk from medical radiation
My bias in favor of CT studies
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If the appendix is seen and normal, no
appendicitis
If the appendix is not seen, but no other
abnormalities identified, very low chance of
appendicitis
If the appendix is inflamed, then surgery
If the appendix is not seen but inflammation
present, follow closely
Trends for the future
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Better physician and patient education
Clinical decision rules to minimize need for
imaging
Awareness of the issues and time constraints
upon ED physicians for rapid diagnosis
Development of alternatives to CT studies
Technical alteration of CT protocols to
minimize radiation exposure
Conclusions
Conclusions
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There is still controversy concerning diagnostic
imaging for appendicitis in pediatric patients
We are pro-active in keeping medical radiation
exposure as low as reasonable achievable
The experience with our pediatric population,
emergency room physician expectations for
accuracy, and surgical follow-up has led us to
recommend CT studies for appendicitis in the
appropriate clinical setting