Patients may prefer radiation risk to surgical risk in diagnosing appendicitisBMJ 2015; 350 doi: https://doi.org/10.1136/bmj.h3493 (Published 30 June 2015) Cite this as: BMJ 2015;350:h3493
- Nigel D’Souza, specialty registrar in general surgery, Department of General Surgery, Queen Alexandra Hospital, Portsmouth PO6 3LY, UK
Many normal appendixes are removed in the United Kingdom. I have worked at hospitals with negative appendicectomy rates (NARs) of 16.8% to 35%,1 consistent with the 20.6% NAR from over 3000 appendicectomies in a largely UK based audit.2 Colleagues from abroad are incredulous at this high rate despite the availability of accurate diagnostic tests.
I had always believed that, in cases of clinical uncertainty, diagnostic laparoscopy was a better option than computed tomography (CT)—until my wife, an anaesthetist, disagreed with me.
Several factors contribute to the UK’s high NAR. Emergency surgery teams work in shifts with frequent patient handover, which has eroded the role of observation and serial examination that can rule out appendicitis. Routine CT is not common, owing to surgeon preference or lack of access. Beds are frequently scarce, pushing surgeons towards an early, definitive management plan: discharge safely or operate. Yet premature discharge may result in a patient with early appendicitis deteriorating outside hospital, and complications can include peritonitis, infertility, and death.
To avoid this scenario, in cases of uncertainty surgeons may perform laparoscopy to both diagnose and treat appendicitis. However, intraoperative diagnosis of appendicitis is not straightforward; more than 30% of appendixes that look normal at laparoscopy are inflamed on histological analysis.3 4 If no other disease is seen at laparoscopy, most UK surgeons remove a normal looking appendix to treat possible non-visible appendicitis and to prevent future appendicitis. “Diagnostic” laparoscopy not only probably lowers the threshold for surgery but usually commits the patient to appendicectomy, leading to a higher NAR.5 6
Finally, patients do not want to be observed in hospital for days, and neither are they happy to be discharged in pain with a clinical diagnosis of “abdominal pain of unknown cause.” Patients expect a definitive diagnosis and treatment of their symptoms.
CT has been used to reduce NAR. The US Surgical Care and Outcomes Assessment Program study achieved an NAR of 4.5% with routine CT in more than 20 000 appendectomies.7 A meta-analysis of 28 studies found that imaging reduced the NAR to 8.7%, down from 16.7% with clinical evaluation alone.8 CT is readily available, easy and quick to perform, and easy to interpret, with a high sensitivity (94%) and specificity (95%).9
CT is not used routinely in the UK to evaluate acute right iliac fossa pain, because of its cost and radiation dose. Instead, ultrasound is the most commonly performed imaging test.2 Ultrasound is cheaper and radiation-free but is operator dependent, and its real world diagnostic accuracy conflicts with the literature; in UK clinical practice as many as 45% of ultrasound scans fail to visualise the appendix.1 Surgeons and radiologists must audit the diagnostic accuracy of ultrasound locally to justify its inclusion in diagnostic pathways. Magnetic resonance imaging has not yet gained widespread acceptance for use in emergency imaging for appendicitis, but it has excellent reported diagnostic accuracy and may offer a radiation-free solution after further research.10
The expense of CT precludes its routine use for diagnosing appendicitis in the NHS—yet it could reduce the considerable costs of a high NAR. A conservative estimate of the cost of a quick laparoscopic appendicectomy is £960 (€1350; $1510) for theatre time alone.11 An unnecessary operation could be prevented by a scan costing £200 to £400. Surgery and inpatient stay in a hospital with a high NAR can cost more than imaging all patients with right iliac fossa pain, studies have shown.12 13 Further costs from unnecessary surgery include treatment of complications and the indirect costs to the wider economy of sick leave for patients and caregivers during convalescence.
Risk of cancer
Radiation exposure from CT increases cancer incidence, although directly determining the exact risk is difficult. Contemporary, low dose CT appendix protocols have reduced the additional lifetime cancer risk in a 30 year old woman to an estimated 0.016%.14 Efforts to avoid CT and its radiation exposure are laudable but should be weighed against the complications that occur in 10.7% of patients who have normal appendixes removed.2 While morbidity from appendicectomy is mostly minor in fit patients, it may require further radiological or operative intervention. Balancing a 0.016% risk of cancer against a 10.7% risk of complications is difficult, but surgeons currently do so without discussing it with patients.
It is unclear whether all patients should be scanned routinely to achieve a lower NAR. Scanning all male patients may be of less benefit than scanning all female patients, who have a higher NAR because of potential gynaecological conditions that can mimic appendicitis. Patients with a clear diagnosis of appendicitis (reflected by a high Alvarado or Andersson score) may also be irradiated unnecessarily. However, studies have shown that routine use of CT can result in a lower NAR than its use in selected patients.15 16 These studies were underpowered, so further research is needed to determine which patients to scan to decrease the NAR.
A better service for patients
CT seems to provide a cheaper and better service for patients, enabling early diagnosis or patient discharge without the need for prolonged observation or unnecessary surgery. We should ask patients whether they prefer the risks of radiation to the risks of surgery to diagnose appendicitis.
Cite this as: BMJ 2015;350:h3493
Competing interests: I have read and understood the BMJ policy on declaration of interests and have no relevant interests to declare.
Provenance and peer review: Not commissioned; externally peer reviewed.