In this episode on Appendicitis Controversies, we have the continuation of our discussion on abdominal pain emergencies with Dr. Brian Steinhart & Dr. David Dushenski. We kick off the discussion with key clinical pearls and pitfalls in the history and physical exam with their respective liklihood ratios when assessing patients with abdominal pain for appendicitis – a diagnosis that is still sometimes missed despite its prevalence. Dr. Dushenski hacks apart the Alvarado and Appendicitis Inflammatory Response Scores and we discuss the value of WBC, CRP and urinalysis in the work-up of appendicitis. Next up are the controversies of imaging algorithms using ultrasound and CT abdomen, as well as the factors affecting which imaging algorithm you might pursue. We wrap up the discussion on Appendicitis Controversies with a critical look at the value of antibiotics in the ED for appendicitis and which patients might be appropriate for non-surgical management.

Written Summary and blog post by Claire Heslop, edited by Anton Helman April, 2014

History and Physical Examination Pearls for Appendicitis

The signs most likely to be associated with appendicitis in one meta-analysis were:

  • rigidity (+LR = 4)
  • positive psoas sign (+LR = 2.38)
  • fever (+LR = 1.94)

The positive LR of rebound tenderness varied too much to make definitive recommendations (+LR = 1.1-6.3)

Guarding and rectal tenderness were not found to be significant signs

The most predictive signs of appendicitis in another meta-analysis (Br J Surg, 2004) were those involving peritoneal irritation:

  • rebound tenderness (+LR = 1.99)
  • percussion tenderness (+LR = 2.86)
  • guarding (+LR = 2.48)
  • rigidity (+LR = 2.96)

Recurrent pain decreases the likelihood of appendicitis but does not rule it out (chronic recurrent appendicitis is a well known entity)

DRE has limited role in diagnosis of acute, undifferentiated abdominal pain

Important to consider pelvic exam in females with undifferentiated abdominal pain. Remember, cervical motion tenderness does not rule out appendicitis!

Atypical presentations: obese, immunocompromised, extremes of age, diabetics

Pain while traveling over speed bumps increased the likelihood of appendicitis in one study (BMJ 2012)

 

Does Delay in Diagnosis Increase the Rate of Appendix Perforation?

  • Delay in seeking care is a risk factor for perforation (time from symptom onset to ED)

 

Clinical Decision Rules for Appendicitis

ALVARADO score:  (MANTRELS)

Migration of pain RLQ (1 point)

Anorexia (1 point)

N/V (1 point)

Tenderness in RLQ (2 point)

Rebound pain (1 point)

Elevated temp >= 37.3 (1 point)

Leukocytosis >=10 (2 point)

Shift of WBC to left (1 point)

Score of 7 or more has positive LR of 4.0. Score of less than 7 has negative LR of 0.2.

Alvarado score NOT recommended by our experts as it under-performs in elderly, children and women; AND physician judgment may outperform the score.

Appendicitis Inflammatory Response Score (AIP Score)

Vomiting (1)

Pain right inferior fossa (1)

Rebound tenderness (1-3) Temp >=38.5 (1)

PMN (1-2)

WBC (1-2)

CRP (1-2)

Score 0-4 is low probability of appendicitis, 9-12 high probability

Expert interpretation of literature on AIP Score: No better than Alvarado score

 

Lab Values in Appendicitis Controversies

  • Despite the EM community’s general attitude that WBC is generally non-contributory for appendicitis, studies show WBC > 10 has a Positive Likelihood Ratio (+LR) = 2.4; Negative LR = 0.25 which is as good or better than any single clinical history/physical factor
  • Sensitivity of WBC increases with duration of illness, so that WBC may be more useful in late presenters
  • Combining WBC and CRP increases predictive power to both rule in and rule out appendicitis with very good sensitivity and specificity
  • Urinalysis – in appendicitis, inflamed appendix can abut the ureter and cause ureter inflammation, resulting in a significant WBC in the urine (don’t assume UTI!)

 

Imaging for Appendicitis

Factors Affecting Imaging in Appendicitis

1. Duration of Pain:

  • Ultrasound sensitivity increases with duration of pain (as does clinical exam & lab tests!)
  • CT sensitivity unchanged with duration of pain

2. Body Habitus:

  • Ultrasound accuracy is increased in slim patients
  • CT accuracy is increased in obese patients

3. Number of ultrasounds done at your institution for appendicitis – US sensitivity was 78% in centres that use it in 90% of cases, 52% in centres that use it in 50% of cases, 35% in centres that use it in 10% of cases

The Effect of Abdominal Pain Duration on the Accuracy of Diagnostic Imaging for Pediatric Appendicitis. Annals of Emergency Medicine. July 30th, 2012. (Free full pdf)

Abdominal pain duration impacts the accuracy of ultrasound for diagnosing pediatric appendicitis. Evid Based Med 2013 (Free full pdf)

 

Ultrasound for Appendicitis

  • First line in: young, non-obese patients with symptoms > 12h
  • Dependent on operator skill. More impact of patient’s body habitus. Bowel gas can hinder image acquisition
  • Diagnostic Criteria:
  1. Non-compressible appendix
  2. No peristalsis
  3. Diameter > 6mm
  • Other suggestive findings (secondary ultrasound signs can be helpful in your post-test probability):
  1. Appendicolith
  2. Hyperechoic fat
  3. Free fluid in males

Appendix ‘not visualized’

  • The NPV for ultrasound that reports ‘appendix not visualized’ is 85-95% (you don’t necessarily need to go onto to CT abdomen to rule out appendicitis (see alternate option below)
  • Consider your pre-test probability and secondary ultrasound findings (see above)

One option after equivocal ultrasound for appendicitis: observe patient for 8hrs, then re-examine +/- re-ultrasound (remember that ultrasound sensitivity increases with time).

  • US should/could be first line for most patients (esp young, slim, lat in presentation)
  • There is a low risk of appendicitis after equivocal US
  • Low risk slim pt + equivocal US = No CT
  • Low risk slim pt + equivocal US ?observe +/- repeat US as time from onset of pain improves sensitivity

Appendix not seen: the predictive value of secondary inflammatory sonographic signs. Pediatr Emerg Care. 2013

For an analysis on ‘Appendix not seen’ visit Ryan Radecki’s Emergency Medicine Literature of Note

For a dive into the role of POCUS for appendicitis in the ED visit Greg Hall’s post (EM Cases guest expert on Ep18 Utrasound Pearls, Pitfalls & Controversies) at the EDE blog.

 

CT Abdomen for Appendicitis

  • Contrast may increase sensitivity for appendicitis and may be more likely to rule in or out alternate diagnoses
  • IV contrast accentuates periappendiceal and luminal inflammation
  • Oral contrast demarcates appendix from surrounding structures, opacifies ileocecal portion of bowel in 45-60min
  • Rectal contrast: also helps demarcate appendix, can administer just prior to CT, thereby reducing time to wait for CT
  • CT non-contrast – sensitivity 93%, specificity 98%
    CT with PO/IV contrast – sens 93%, spec 93%
    CT with rectal contrast – sens 97%, spec 97%

Studies have failed to demonstrate reduction in negative appendectomy rate in men despite increased CT use

 

Treatment of Appendicitis Controversies: Antibiotic & Surgical Management

Which patients with Appendicitis Require Antibiotics in the ED?

  • No good evidence for routine administration of antibiotics in ED for appendicitis effecting clinical outcomes
  • Patients should receive prophylactic antibiotics within 60min window prior to surgical incision
  • Consider antibiotics if there is delay to OR

Medical vs Surgical  Management

Oral antibiotics vs. immediate OR for acute, uncomplicated appendicitis – Amox-Clav found to be non-inferior to emergency appendectomy

However, associated with increased risk for recurrent disease

Candidates for medical management (decision best made in conjunction with surgical colleagues): Early, non-perforated, < 24h from onset of symptoms, no appendicolith or masses causing persistent obstruction of the appendix

Amoxicillin plus calvulanic acid versus appendectomy for treatment of acute uncomplicated appendicitis: an open-label, noninferiority, randomized controlled trial. Lancet 2011

Update 2014: The NOTA study (Non Operative Treatment for Acute Appendicitis) shows that antibiotics without surgery may be a viable option for simple appendicitis, although it showed a 12% treatment failure rate. See Ryan Radecki’s analysis on EM Literature of Note and the abstract.

Update 2015: Head over to the Skeptics Guide to EM for an analysis of two trials looking at the non-operative treatment of acute appendicitis.

Now Test Your Knowledge

Answer:

  • Migration of pain, RLQ pain, psoas sign, fever, pain before vomiting, rebound tenderness all significantly increase likelihood of appendicitis
  • Recurrent pain decreases the likelihood of appendicitis but does not rule it out (chronic recurrent appendicitis is a well known entity)
  • Pain while traveling over speed bumps increases the likelihood of appendicitis in one study

Answer: Obese, immunocompromised, extremes of age, diabetics are groups of patients that typically present atypically

Answer: Alvarado score is NOT recommended by our experts as it under-performs in elderly, children and women; AND physician judgment may outperform the score.

Answer:

  • WBC > 10: (Positive Likelihood Ratio (+LR)) = 2.4; Negative LR = 0.25) as good or better than any single clinical history/physical factor
  • Sensitivity of WBC increases with duration of illness
  • Combining WBC and CRP increases predictive power to both rule in and rule out appendicitis

Answer:

  • Delay in patients seeking care is a risk factor for perforation (time from symptom onset to ED)
  • Multiple studies have shown that in-hospital delay to OR

Answer:

  1. Duration of Pain:
  • Ultrasound sensitivity increases with duration of pain (as does clinical exam & lab tests!)
  • CT sensitivity unchanged with duration of pain
  1. Body Habitus:
  • Ultrasound accuracy is increased in slim patients
  • CT accuracy is increased in obese patients
  1. Number of ultrasounds done at your institution for appendicitis

Answer:

  • The NPV for ultrasound that reports ‘appendix not visualized’ is 85-95% (you don’t necessarily need to go onto to CT abdomen to rule out appendicitis (see alternate option below)
  • Consider your pre-test probability and other ultrasound findings

One option after equivocal ultrasound for appendicitis: observe patient for 8hrs, then re-examine +/- re-ultrasound (remember that ultrasound sensitivity increases with time).

Answer:

  • No good evidence for routine administration of antibotics in ED for appendicitis effecting clinical outcomes
  • Patients should receive prophylactic antibitoics within 60min window prior to surgical incision
  • Consider antibiotics if there is delay to OR

Answer: Candidates for medical management (decision best made in conjunction with surgical colleagues): Early, non-perforated, < 24h from onset of symptoms, no appendicolith or masses causing persistent obstruction of the appendix.

Dr. Helman, Dr. Steinhart and Dr. Dushenski have no conflicts of interest to declare.

 

Key References

RE Andersson, Repeated clinical and laboratory examinations in patients with an equivocal diagnosis of appendicitis. W J Surg 2000; 24 479-485 (Free full pdf)

 Andersson RE, Meta-analysis of the clinical and labratory diagnosis of appendicitis. Br J Surg, 20014 Jan;91(1):28-37.

Pain while traveling over speed bumps increased the likelihood of appendicitis in one study –  Helen F Ashdown. Pain over speed bumps in diagnosis of acute appendicitis: diagnostic accuracy study.  BMJ 2012;345:e8012 doi: 10.1136/bmj.e8012

Kessler C, et al. Utility of the digital rectal examination in the emergency department: a review. J Emerg Med. 2012 Dec;43(6):1196-204. doi: 10.1016/j.jemermed.2012.06.015. Epub 2012 Aug 9.

Steward et al. 2012. J Clin Ultrasound, 40(8): 455-61. Sonography for appendicitis: nonvisualization of the appendix is an indication for active clinical observation rather than direct referral for computed tomography.

Chiu et al. 2013. Acad Radiol, 20(1): 73-8. Whether intravenous contrast is necessary for CT diagnosis of acute appendicitis in adult ED patients?

Mittal MK, Performance of ultrasound in the diagnosis of appendicitis in children in a multicenter cohort. Acad Emerg Med. 2013 Jul;20(7):697-702. doi: 10.1111/acem.12161.

Bachar, R. The Effect of Abdominal Pain Duration on the Accuracy of Diagnostic Imaging for Pediatric Appendicitis. Annals of Emergency Medicine. July 30th, 2012. (Free full pdf)

Adrea S Doria. Abdominal pain duration impacts the accuracy of ultrasound for diagnosing pediatric appendicitis. Evid Based Med 2013;18:224-225 doi:10.1136/eb-2012-101170 (Free full pdf)

Pediatrics. 2014 Jan;133(1):e88-95. doi: 10.1542/peds.2013-2208. Epub 2013 Dec 30.
Prospective evaluation of a clinical pathway for suspected appendicitis. 

Clyde C, Timing of intervention does not affect outcome in acute appendicitis in a large community practice?Am J Surg. 2008 May;195(5):590-2.

Ingraham AM Effect of delay to operation on outcomes in adults with acute appendicitis. Arch Surg. 2010 Sep;145(9):886-92. doi: 10.1001/archsurg.2010.184.

Michael F. Ditillo. Is It Safe to Delay Appendectomy in AdultsWith Acute Appendicitis? Annals of Surgery • Volume 244, Number 5, November 2006

Kessler N, Radiology. 2004 Feb;230(2):472-8. Epub 2003 Dec 19. Appendicitis: evaluation of sensitivity, specificity, and predictive values of US, Doppler US, and laboratory findings.

Toorenvliet BR, et al. Routine ultrasound and limited computed tomography for the diagnosis of acute appendicitis. World J Surg. 2010 Oct;34(10):2278-85

Andersen BR, Kallehave FL, Andersen HK. Antibiotics versus placebo for prevention of postoperative infec- tion after appendicectomy. Cochrane Database Syst Rev. 2005;(3):CD001439. PubMed PMID: 16034862. (Cochrane review)

Vons C eta l. Amoxicillin plus calvulanic acid versus appendectomy for treatment of acute uncomplicated appendicitis: an open-label, noninferiority, randomized controlled trial. Lancet 2011; 377:1573

Mason RJ, Moazzez A, Sohn H, Katkhouda N. Meta-analysis of randomized trials comparing antibiotic therapy with appendectomy for acute uncomplicated (no abscess or phlegmon) appendicitis. Surg Infect (Larchmt). 2012;13:74-84.

 

 

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