Easily Missed?

Appendicitis

BMJ 2011; 343 doi: http://dx.doi.org/10.1136/bmj.d5976 (Published 6 October 2011)
Cite this as: BMJ 2011;343:d5976

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In the linked narrative review (doi: 10.1136/bmj.d5976) authors give a clear overview of the difficulties physicians face when evaluating patients with suspected acute appendicitis. We would like to comment on a few issues raised in this article.

The authors state that the 'diagnostic accuracy of general practitioners in relation to appendicitis is high' and substantiate this statement with a reference to a 17-year old retrospective review of 100 hospital records of children under the age of six who underwent appendectomy.1 In our opinion no conclusions can be drawn based on the results of this study because of its retrospective design, selection of pediatric patients and small sample size. Most patients with acute abdominal pain will be referred to or directly present at the emergency department for evaluation of their complaints. Observational cohort studies show that clinical evaluation of suspected appendicitis without imaging leads to 10-40% negative appendectomies and 12% missed cases of appendicitis.2 3 Negative appendectomies increase mortality, prolong hospital stay, and increase the risk of infectious complications.4 Missed appendicitis increases the risk of perforated appendicitis, peritonitis, abscesses and may lead to a two to tenfold increased mortality rate.5 6

Lewis et al. also state that only 50% of patients present with a 'classical presentation' of acute appendicitis, based on Murphy's personal experience after 2000 appendectomies in 1904.7 This reference is more than a century old, and the present clinical setting as well as the basic principles of medical research are completely different. A very recent study shows that the classical presentation of acute appendicitis with a history of pain migration to the right lower quadrant, and tenderness and rigidity in the right lower quadrant was present in only 6% of patients with suspected appendicitis.3 The discriminative power of individual and combined clinical features and laboratory test results for appendicitis is weak in patients with suspected appendicitis.2 3

For these reasons diagnostic imaging is needed in patients with suspected appendicitis. Several studies, including two randomised controlled trials, have shown that routine use of imaging has a positive effect on patient outcomes in patients with suspected appendicitis.8 9 The American College of Radiology has published a consensus document on appropriateness criteria for imaging evaluation of patients with acute pain in the right lower quadrant. The consensus finds CT the most appropriate for these patients.10 Concerns about induction of malignancy due to radiation by CT are balanced against the morbidity and mortality that are associated with a missed diagnosis. However, possibilities to reduce CT related exposure to radiation are explored. Recently we have published the results of a multicenter diagnostic accuracy study in over 1000 patients with acute abdominal pain, showing that initial ultrasonography in all patients and additional CT in case of negative or inconclusive ultrasonography was the most sensitive imaging strategy to detect urgent disease, while minimizing exposure to radiation.11 A new national acute appendicitis guideline is partly based on these results and became effective in March 2010.12 Also low dose CT protocols and MRI show promising results and will be further explored in the near future.13 14

In conclusion, we disagree with the authors that 'appendicitis is predominantly a clinical diagnosis that can be supported by simple blood tests--specialist tests aren't usually required.' A thorough history, physical examination aided by laboratory tests is essential to come to a clinical suspicion of appendicitis. However, the clinical diagnosis of acute appendicitis is unreliable and imaging is needed to substantiate this diagnosis, as the standard treatment of appendicitis is surgical and diagnostic mistakes should be minimized.

References

1. Wilson D, Sinclair S, McCallion WA, Potts SR. Acute appendicitis in young children in the Belfast urban area: 1985-1992. Ulster Med J 1994;63:3-7.

2. Andersson RE. Meta-analysis of the clinical and laboratory diagnosis of appendicitis. Brit J Surg 2004;91:28-37.

3. Lam?ris W, Randen A van, Go PM, Bouma WH, Donkervoort SC, Bossuyt PM, et al. Single and combined diagnostic value of clinical features and laboratory tests in acute appendicitis. Acad Emerg Med 2009;16:835-42.

4. Flum DR, Koepsell T. The clinical and economic correlates of misdiagnosed appendicitis: nationwide analysis. Arch Surg 2002;137:799- 804.

5. Velanovich V, Satava R. Balancing the normal appendectomy rate with the perforated appendicitis rate: implications for quality assurance. Am Surg 1992;58:264-9.

6. Andersson RE. The natural history and traditional management of appendicitis revisited: spontaneous resolution and predominance of prehospital perforations imply that a correct diagnosis is more important than an early diagnosis. World J Surg 2007;31:86-92.

7. Murphy J. Two thousand operations for appendicitis, with deductions from his personal experience. Am J Med Sci 1904;128:187-211.

8. Ng CS, Watson CJE, Palmer CR, See TC, Beharry NA, Housden BA, et al. Evaluation of early abdominopelvic computed unknown cause: prospective randomised study. BMJ 2002;325:4-7.

9. Lee CC, Golub R, Singer AJ, Cantu R, Levinson H. Routine versus selective abdominal computed tomography scan in the evaluation of right lower quadrant pain: a randomized controlled trial. Acad Emerg Med 2007;14:117-22.

10. Rosen MP, Ding A, Blake MA, Baker ME, Cash BD, Fidler JL, et al. American College of Radiology Appropriateness Criteria. Right Lower Quadrant Pain -- Suspected Appendicitis. 2010; (assessed October 5, 2011at http://www.acsearch.acr.org)

11. Lam?ris W, Randen A van, Es HW van, Heesewijk JPM van, Ramshorst B van, Bouma WH, et al. Imaging strategies for detection of urgent conditions in patients with acute abdominal pain: diagnostic accuracy study. BMJ 2009;338:b2431-b2431.

12. Bakker OJ, Go PM, Puylaert JB, Kazemier G, Heij HA. Guideline on diagnosis and treatment of acute appendicitis: imaging prior to appendectomy is recommended. Ned Tijdschr Geneesk 2010;154:A303.

13. Kim SY, Lee KH, Kim K, Kim TY, Lee HS, Hwang SS, et al. Acute Appendicitis in Young Adults: Low- versus Standard-Radiation-Dose Contrast -enhanced Abdominal CT for Diagnosis. Radiology 2011;260:437-45.

14. Cobben L, Groot I, Kingma L, Coerkamp E, Puylaert J, Blickman J. A simple MRI protocol in patients with clinically suspected appendicitis: results in 138 patients and effect on outcome of appendectomy. Eur Radiol 2009;19:1175-83.

Competing interests: None declared

Marjolein M.N. Leeuwenburgh, research fellow

Marja A. Boermeester, consultant surgeon and clinical epidemiologist, and Jaap Stoker, professor of radiology.

Academic Medical Centre Amsterdam - University of Amsterdam

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17 October 2011

Eliciting Rovsing's sign, as classically described, is not simple palpation of the left iliac fossa causing pain to be felt in the right iliac fossa. Nor is it peritoneal irritation that is elicited; instead, Rovsing's original description was an attempt to distend the caecum and appendix by pushing on the left colon in an anti-peristaltic direction. Studies in the 1950s on intra-operative and cadaveric manometric measurements confirmed that the mechanism sounds as implausible now as it did then.[1][2] The same studies found or allude to a small sensitivity and specificity in the diagnosis of appendicitis.

More recently, a 2005 paper states a sensitivity of 30.1% and specificity of 84.4%,[3] but given the widespread ignorance of the original sign as described by Rovsing's, this is best regarded as a Rovsing's-like sign and is probably, at best, merely a surrogate of peritoneal irritation, of any cause, centred in the right iliac fossa but extending into the left iliac fossa.

[1] Davey WW. Rovsing's sign. British medical journal. 1956 Jul 7; 2(4983):28-30.

[2] Yasui H. Rovsing's sign. British medical journal. 1958 May 17; 1(5080):1163.

[3] Kharbanda AB, Taylor GA, Fishman SJ, Bachur RG. A clinical decision rule to identify children at low risk for appendicitis. Pediatrics. 2005 Sep; 116(3):709-16

Competing interests: None declared

Mark Ong, Histopathology Registrar

London

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