Imaging for Acute Appendicitis

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					Imaging for Acute

    Appendicitis

        LT David Bruner
      LCDR Todd Parker
 Staff Emergency Physicians
           April 2009
               Objectives

 Cases
  Consider what you would do

 Imaging choices
  US
  CT
    Non-contrast vs oral contrast vs rectal
  MRI

 Reconsider Cases/Discussion
                         Case 1
 15 yo male - 1 day worsening abdominal pain
   Periumbilical  migrated to RLQ

   Nausea, vomiting, anorexia, hurts to walk, no fever


 RLQ guarding / rebound / Heel Tap / Rovsing


 Labs:
   WBC – 8.9 H/H – 12/37

   UA – 12 WBC, Pos Leuk Est, rare bacteria


 What imaging, if any?
                      Case 2
 8 yo f - >24 hrs of worsening RLQ pain
   Diarrhea and nausea, subjective fever

   Urinary frequency / abdominal pain with micturition


 T – 101.0    P – 121      BP – 108/62

 RLQ TTP at McBurney’s point
   Guard/mild rebound


 UA Negative          WBC – Pending
                          Case 3
 37 yo man - 30 hours of worsening RLQ pain

   N/V and Fever to 100.5

   No urinary symptoms

   PMHx of kidney stones – but this is different

   Wife and daughter recently sick with N/V/D


 RLQ TTP with guarding and rebound

   UA Negative


 Does he need a CT?

   If so, what kind
                          Case 4
 31 yo female - 2 days worsening pain

   Epigastric at first, now only RLQ

   Nausea, subjective fever, menses

   No urinary symptoms


 Positive McBurney’s, Rovsing, Heel Tap

   No CMT or adnexal masses felt


 HCG negative, UA negative


 Imaging?
              Case 4-1

 Same as Case 4 except . . . .
  No vaginal bleeding

  HCG Positive

  ED US reveals IUP at 10 weeks


 Imaging?
                        Case 5
 73 yo female
   30 hours lower abdominal pain and nausea

   No vomiting /diarrhea, fever, bloody stool, or dysuria


 Hx of HTN
   Otherwise negative PMHx and PSHx


 Bilateral Lower Quad TTP R > L, mild guarding


 P – 98    T – 100.8      BP – 135/76
       Clearly Imaging Reduces NAR
Wagner et al., Surgery. 2008; 144(2)
                                          Guss et al., “Impact of
     Acceptable Negative               Appendectomy on the
                                          Abdominal Helical CT
- Retrospective review of four-year time
         before (NAR)?
periodsRate and after frequent CT
                                          Rate of Negative
                                          Appendicitis” JEM 2008; 34(1)
- NAR decreased 16% to 6%
- NAR decreased mostly due to adult women
                                            - Retrospective review of
     Historically 10-20%
- No change in NAR with kids (8%)
                                            before and after frequent CT
- Adult male decreased from 9% to 5% (NSS)
                                            - Decrease in NAR from 15.5%
- Adult women decreased 20% to 7%
         Higher % acceptable in women and peds
                                            to 7.6%
                                            - 12% CT rate before readily
Kim, K. et al, “The Impact of Helical CT on available, 81% after
     With increased imaging
Negative Appendectomy Rate: A Multi-
Center Comparison; JEM 2008; 34(1)
        5-10% NAR
        Significantly increased pre-operative CT
- CT Rate and NAR inversely related
- NAR decreased 20% to 6%
            From 32% on negative scans
- Limited by no follow up to 95% - Wegner study
                  Ultrasound
 Very safe! No radiation, no contrast
  required

 Sensitivity and Specificity:
                                  Findings on US for
     Adult - Sensitivity – 74-83%, Specificity – 93-97%
                                     appendicitis
                              - Non-compressible
   Pediatrics – Sensitivity -88%, Specificity – 94%
                          appendix
                          - Appendix >6mm diameter
 Variables: Body habitus, Location, Skill
                          - Signs of perforation
                              -Free fluid
                              -Abscess
 If can’t visualize – need to move on to the
  next step
     Computed Tomography
 High overall accuracy, Sens, Spec, NPV, and PPV


 Available at all hours


 Risks:

   Radiation

   Contrast problems

      Allergic reactions

      Nephrotoxicity
                  Oral Contrast
           Pros                       Cons
 Sensitivity 94-98% /       Large volume contrast
  specificity 95-99%           What if vomiting?
                                 If not, probably will
 Alternative diagnoses          Risk of aspiration
                               Aren’t they NPO?
 May see extravasation
                             Increases difficulty of
 Better if little intra-     assessing bowel wall
  abdominal fat
                             2 hour delay
 Fluid collections
                               Delays surgical decision
 Comfort with reading         Risk of perforation
  contrasted vs non-           4-8 hrs to advance
  contrasted
        Rectal Contrast CT

 Gravity drip – little risk of perforation


 Few minutes to perform scan
   As little as 15 minutes


 Accuracy equal to oral contrast


 No reported increased discomfort
         Rectal contrast study
 Berg ER, et al, Acad Emerg          Stephen AE, et al., J Ped
  Med. 2006 Oct; 13(10)                Surg. Mar 2003; 38(3)

   Compared oral and rectal
     contrast CT in a randomized        96/283 kids had rectal
     trial                                contrast

   Showed decreased length
                                        95% Sens and PPV
     of stay in the ED by one hour

   No increased patient                Missed cases still went
     discomfort between oral or
                                          to OR because of
     rectal contrast
                                          clinical scenario
   Equal diagnostic accuracy.
           Non-Contrast CT
 For diagnosis of appendicitis
   No need to drink contrast – no delay


 No change in diagnostic accuracy with IV
  Contrast

 Sensitivity 94-98%     Specificity – 95-99%

 Significant supporting evidence for non-
  contrast CT in suspected appendicitis
  Lane MJ, et al, Radiology. 1999; 213

 300 consecutive patients
   Non-contrast CT for appendicitis


 Compared with surgical pathology results
   96% sensitive

   99% specific

   97% accuracy


 “Stacked the Deck”
Hoecker CC, et al, JEM. May 2005

 Retrospective study 112 children
   Atypical presentation (13% of total abd pain pts)

   CT’d without PO contrast (helical CT)

   40% positive appendicitis rate


 Compared to those given PO contrast (prev
  studies)
   Equal sensitivity and specificity in both groups


 Overall 91% diagnostic accuracy
Lowe LH, et al., Am J Roent. Jan 2001

 Retrospective cohort of 72 children with
  non-contrast CT (atypical PE)

 97% sensitive (95% CI, 91-100%)


 100% specific (95% CI, 96-100%)


 Only took 5 minutes to perform the study
Lowe, L. H., et al, Radiology 2001; 221
 75 consecutive patients - non-contrast CT
   Atypical/Equivocal PE findings


 Compared residents’ and attendings’ reads


 Results:
   91% agreement in reading studies

   96% specificity and 88% accuracy in residents

   98% specificity and 97% accuracy in attendings

   Attendings more confident of reads
Ege G, et al., Br J Radiology. 2002; 75
  296 adults non-con CT for suspected appendicitis

    Equivocal Exams Only

    45% positive for appendicitis


  Compared with surgical pathology or follow up


  96% sens and 98% spec/ 97% PPV and 98% NPV


  Recommends non-con CT for diagnosis of appendicitis in
   adults
    Negative study requires observation or follow up
Anderson BA, et al, Am J Surg. Sep 2005
  Study      # of     Sens     Spec    Accura
  type     studies                       cy
   Systematic review of 23 studies
  Rectal   5      97      97     97
    (19 prospective, 4 retrospective)
   Oral    2      83      95     92
  Oral +   2      95      96     96
  Rectal
   Over 3700 patients over 16 years
 Oral + IV
    old    7      93      92     92
 NonCon    8      93      98     96
 Oral vs             92 vs 94 95 vs 97 92 vs 96
 None
                  IV Contrast
 Basak S, et al., J Clin Imag. 2002; 26.
   Performed study without contrast then with contrast
   No difference in making the diagnosis with IV or no
    contrast
   Some even thought IV obscured the intra-abdominal
    structures


 Keyzer, C., et al, Am J Roent. August 2008
   Equal agreement between resident and attending
    reads
   Equal ability to visualize the appendix
     Alternative Diagnoses?

 Likely the most compelling argument


 What are the data?
   No good head to head studies
   Plenty of data showing that both
    enhanced and unenhanced find
    alternative diagnoses
    Which is best?
     Alternative Diagnoses in Non-
           Contrasted Studies
 Malone, A. et al, Am J Roentgen 1993
   35% alternative diagnosis
   Diverticulitis, Ovarian Cysts or masses, PID, IBD


 Lane MJ, et al, Radiology. 1999
   21% alternative diagnosis
   Ureteral Calculi, Diverticulitis, Chron’s, Mesenteric Adenitis,
    Neoplasms


 Alternative diagnoses advocated by IV and Oral/Rectal
   contrast
    Epiploic appendagitis, diverticulitis, Meckel’s Torsion,
      gynecologic disorders, obstructive uropathy, RLL PNA

 How much advantage does contrasted vs non-contrasted
   study provide?
            Why Scan at All?

 Kalliakmans V, et al., Scan J Surg. 2005; 94(3)
   717 adults evaluated for appendicitis by 6 surgeons

 Normal practice patterns - recorded decisions

 11% Negative appendectomy rate based on
  history, physical, and labs

 CT did not change diagnostic accuracy except
  in cases of atypical history and physical
   Recommends only using CT in equivocal cases
               CT in Pediatrics

 Increased lifetime cancer risk

 Less intra-abdominal fat
  Garcia K, et al, Radiology. Feb 2009
 Is a negative CT enough?
  • 1139 pediatric cases over 4 years
  • CT results compared to surgical pathology or follow up
  • All except 8 had CT with IV contrast only
       • NPV (non-visualized appendix) – 98.7%
       • NPV (Visualized) – 99.8%
       • NPV (Partially visualized) – 100%
           What About MRI?
 Pros: No radiation and can do reconstructions

 Cons: Cost, Time, not always available 24/7

 Highly accurate, operator dependent

 Sensitivity 93-99% Specificity 94-100%

 Less robust evidence, but most studies show
  reliable and reproducible diagnostic accuracy

 Caution with gadolinium if pregnant
 Pregnancy and Appendicitis
   Pedrosa, I et al, Radiology. Mar 2006
 Same incidence as non-pregnant
   • 51 consecutive pregnant pts suspicion for appendicitis
 Questionable evidence of appendix moving out of
  RLQ • Underwent MRI if US inconclusive
   • 4 had appendicitis – MRI correctly dx all
 Risk of surgery/anesthesia is less than risk of mortality to
   • 3 inconclusive – clinically resolved spontaneously
  mother and fetus if appendicitis is missed or
   • Sens – 100% / Spec
  perforation occurs – 93.6% / Accuracy – 94%
  Pedrosa, I et radiation risks to fetus – right?
 Want to avoid al, Radiology. Mar 2009

 US may miss appendix in a different location
  • 148 consecutive pregnant pts suspicion for appendicitis
  • Underwent sensitivity and specificity first
 MRI has goodMRI, 140/148 had ultrasoundin appendicitis
  • 14 had appendicitis – MRI correctly dx all, U/S 5/14
  • 9 False-Positives
  • Sens – 100% / Spec – 93% / PPV – 61% / NPV – 100%
            Cases
 What did you decide to do?
 Case 1 – 15 yo male with 1 day
of pain, migration, and peritonitis

 No imaging – take to the OR and
  “The routine use of CT for adult male
  Kalliakmans V, et al., Scan J Surg. 2005; 94(3
   pediatric patients with a clinical picture
   Guss DA, et al., JEM. 2008; 34(1)
  suggestive of acute appendicitis should
  Wagner PL, et al., Surgery. 2008 Aug; 144(2)
         therefore be discouraged.”

  All showed   no improved negative appy
   rate for males with pre-operative CT scanning.
Case 2 – 8 yo girl, 1 day of pain,
    peritoneal signs, fever

 Actual case
   US done first
   Then an MRI was performed
   Then went to the OR

 Recommendation in this case
   US or straight to the OR
   CT vs MRI if still unsure
            Another case

 13 year old girl

 Ultrasound Positive Appy

 Straight to the OR
Case 3 – 37 yo male, 36 hours of
pain, RLQ ttp, fever, hx of stones

 Non-contrast CT

 What if his WBC count was 19.5 with a
 left shift?

 No imaging . . . To the OR?
  Case 4 – 31 yo female, good
     exam, negative urine
 Do you want to avoid radiation?


 Could start with US


 Could go directly to CT


 Little reason for MRI
              Case 4-1 - Pregnant
   US first

   MRI vs CT

   Serial exams


Dose of radiation thought to be teratogenic and increase risk of cancer in
fetuses is 50 mGy

ACOG gives CT a level 2 recommendation
- Must weigh risks and benefits
     Case 5 – 73 yo woman

 Non-contrast CT


 What if her Creatinine is 2.2?
   Does she need IV Contrast
             Take home points
 Classic presentations do not require imaging
   Reserve imaging for equivocal cases
   Abdominal CT estimated increase cancer risk 1 in 2000

 CT not shown to decrease NAR in men and children

 Multiple studies suggest oral contrast provides no added
  value – no need to make them drink

 Consider US first for kids, women, and pregnant

 MRI is a reasonable alternative if available

 Can CT pregnant women safely – inform of risks

 Consider Informed Consent in certain cases
Discussion