Intended for healthcare professionals

Practice Easily Missed?

Appendicitis

BMJ 2011; 343 doi: https://doi.org/10.1136/bmj.d5976 (Published 06 October 2011) Cite this as: BMJ 2011;343:d5976

Appendicitis is easily missed or wrongly diagnosed - imaging is needed

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: No competing interests

17 October 2011
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