# Ultrasound vs. Reality: A Multi-centre Study of Real-World Imaging Practices in Suspected Appendicitis in the United Kingdom

## TL;DR

This study compares the effectiveness of ultrasound, CT, and MRI scans in diagnosing appendicitis in the UK, finding that CT is most reliable while ultrasound has significant limitations.

## Contribution

The study provides real-world data on imaging practices and diagnostic accuracy for appendicitis in the UK, highlighting the underperformance of ultrasound in adult patients.

## Key findings

- Ultrasound had a sensitivity of 56.25%, with poor performance in adults compared to children.
- CT scans showed nearly 99% sensitivity and were the most commonly used modality.
- MRI scans had 100% sensitivity but were underutilized due to practical limitations.

## Abstract

Background: Appendicitis is one of the leading causes for emergency surgery in the United Kingdom (UK), with approximately 50,000 appendectomies performed annually. While imaging plays an increasingly important role in diagnosis, the lack of specific, unified guidelines guiding the utilisation of various imaging modalities causes ambiguity in how and when various modalities should be used.

Objective: This study aimed to evaluate how various imaging modalities are being used in day-to-day practice, the practical aspects, the challenges, and the benefits of one scan over the others. This was done by comparing the diagnostic accuracy of various scans, such as ultrasound (US), CT, and MRI scans in suspected appendicitis cases.

Methods: We retrospectively reviewed 200 recent appendectomy cases across two major hospitals in Manchester. After excluding 70 patients who either had no preoperative imaging or were diagnosed with something other than appendicitis, we analysed the radiology and histopathology reports of the remaining 130 patients. Special attention was given to the subgroup of 52 patients who initially underwent US.

Results: US had a sensitivity (Sn) of 56.25%, with 21 missed diagnoses later confirmed via CT, MRI, or histopathology. US should be commonly used for those under 18, but surprisingly, approximately two-thirds of US cases were adults, representing an inclination to use US as an initial investigation. In the under-18 group, US Sn was 80%, dropping to just 37.5% in the 18-29-year age group. US was not able to visualise the appendix in 34% (n=18) of patients, missing out on many appendicitis diagnoses. The CT scan was the most utilised scan and had a sensitivity of nearly 99%. The MRI scan, although limited in numbers, had a sensitivity of 100%.

Conclusion: While US offers benefits such as speed and no radiation exposure, its diagnostic reliability varies with the patient’s body habitus and the operator’s skills. The appendix was not identified in a good proportion of patients; however, when the appendix was clearly visualised, it was associated with a better sensitivity. The CT scan was the most utilised scan. It also proved to have excellent sensitivity and is quicker to perform compared to an MRI scan. The MRI scan provides CT equivalent sensitivity but without exposure to harmful radiation. However, it was being underutilised due to limitations in practicality and availability. We routinely request these scans to support the diagnosis of appendicitis, but it is important to understand their diagnostic value, limitations, and when they are most appropriately used.