Appendicitis (really).

Sometimes you read a collection of paper and see common threads. Here are some from BJS Open.

Nihil sub sole novum

The phrase ‘nothing new under the sun’ is often a cry of despair borne from monotony. Is this true for appendicitis? From reading this article from 1893, there are certainly principles that remain constant. There has been a recent flurry of papers on appendicitis published in BJS Open. As I’ve been reading them as they hit early access, I thought it might be interesting to have a look at them and see where they fit in the wider context of the literature and practice. 

We enter 2021 with the non-operative management of acute uncomplicated appendicitis being broadly accepted as a viable option. This has likely been increased by the (ongoing) COVID pandemic, with its subsequent impact on surgical resource and workforce availability.

First of all, appendicitis remains relevant. The paediatric surgery research priority setting exercise had two questions on appendicitis; one on the antibiotic only approach in uncomplicated appendicitis, and one on the use of drains post-operatively.

Telling the difference

And then we turn our attention to discriminating between complicated and uncomplicated appendicitis. What is the best modality? As a profession, we are keen not to over irradiate our patients with excessive CT scans. Naturally, we look to ultrasound and MRI scans. Unfortunately, a systematic review of diagnostic accuracy in all three modalities found limitations in both US and MRI, and a high negative predictive value when CT is used. So that is settled then, CT to reassure us that the patient has uncomplicated appendicitis and can be managed non-operatively.

Caution was raised by a study from Helsinki, Finland. This looked at 837 patients diagnosed with uncomplicated appendicitis on CT scan, and found that at surgery, 22% had perforated. The data is from 2014/2015, which isn’t *that* long ago, although it feels higher than I expected. So perhaps we need a better test to pick out complicated appendicitis?

Blood tests

Enter Kiss et al, who looked at genetic expression in peripheral blood mononuclear cells. This study found upregulation of genes associated with T & B cell interaction in those patients who had phlegmonous appendicitis, and upregulation of markers of antibacterial activity (e.g. monocytes and neutrophils). Perhaps this is interesting and personalised blood test to explore for the future. Point of care testing anyone? On the point of novel tests, an Irish group looked at the role of circulating fibrocytes in the diagnosis of appendicitis. This is a class of cells that is increased in states of inflammation. Sensitivity and specificity were in the high 60s, but in a modest sample that might be expected. Something to investigate further in a larger sample for sure. 

And finally, the role of blood tests in the immunosuppressed, specifically the HIV+ve patient. We classically use blood tests such as leucocyte count or C-reactive protein to aid diagnosis. This study from South Africa showed that, perhaps counterintuitively, CRP levels tended to be higher in HIV+ve patients with appendicitis than HIV-ve patients with appendicitis. Leucocyte levels were lower in the HIV+ve group. Useful to know this data exists as many of the risk models used are not calibrated for this population.

Summary

To wrap this up, I want to point out the opening gambit from the paper by Kiss et al:

‘Surgeons know how to treat appendicitis: either surgically with appendicectomy and supporting measures like abscess drainage, or conservatively without operation’

Whilst we may retain the technical principles of surgery, there is work to do. This seems to be around:

• Improving the diagnosis of appendicitis, hopefully avoiding radiation in the process.
• Accurate estimation of risk of perforation in patients with a diagnosis of appendicitis

Publications arising in the last six months in BJS Open alone suggest that we have a way to go to truly ‘know‘ how to treat appendicitis.

MJL.