Elsevier

The Lancet

Volume 386, Issue 10000, 26 September–2 October 2015, Pages 1278-1287
The Lancet

Series
Acute appendicitis: modern understanding of pathogenesis, diagnosis, and management

https://doi.org/10.1016/S0140-6736(15)00275-5Get rights and content

Summary

Acute appendicitis is one of the most common abdominal emergencies worldwide. The cause remains poorly understood, with few advances in the past few decades. To obtain a confident preoperative diagnosis is still a challenge, since the possibility of appendicitis must be entertained in any patient presenting with an acute abdomen. Although biomarkers and imaging are valuable adjuncts to history and examination, their limitations mean that clinical assessment is still the mainstay of diagnosis. A clinical classification is used to stratify management based on simple (non-perforated) and complex (gangrenous or perforated) inflammation, although many patients remain with an equivocal diagnosis, which is one of the most challenging dilemmas. An observed divide in disease course suggests that some cases of simple appendicitis might be self-limiting or respond to antibiotics alone, whereas another type often seems to perforate before the patient reaches hospital. Although the mortality rate is low, postoperative complications are common in complex disease. We discuss existing knowledge in pathogenesis, modern diagnosis, and evolving strategies in management that are leading to stratified care for patients.

Introduction

Acute appendicitis is one of the most common general surgical emergencies worldwide, with an estimated lifetime risk reported to be 7–8%.1 Accordingly, appendectomy is one of the most frequently performed surgical procedures worldwide and represents an important burden on modern health systems. Despite being so common, a poor understanding of the causes of appendicitis and an absence of reliable discriminators for disease severity still persist. An insufficient amount of clinical research has led to uncertainty about best practice, with subsequent international variation in delivery and, as a possible consequence, variation in outcome. The aim of this review is to provide a state-of-the-art update about the existing controversies in pathogenesis, diagnosis, and clinical management of acute appendicitis.

Section snippets

Epidemiology

Acute appendicitis occurs at a rate of about 90–100 patients per 100 000 inhabitants per year in developed countries. The peak incidence usually occurs in the second or third decade of life, and the disease is less common at both extremes of age. Most studies show a slight male predominance. Geographical differences are reported, with lifetime risks for appendicitis of 16% in South Korea, 9·0% in the USA, and 1·8% in Africa.2, 3

Causes

Direct luminal obstruction can cause appendicitis (often by a

Modern diagnostic strategies

Modern diagnosis aims to first confirm or eliminate a diagnosis of appendicitis, and second to stratify simple and complex disease when appendicitis is suspected. The optimum strategy that limits harm (eg, radiation from imaging) while maintaining a high degree of accuracy has still not achieved consensus, representing the difficulty faced by patients and surgeons.

Primary antibiotic treatment of simple inflamed appendicitis

Recently, antibiotics have been proposed as a single treatment for uncomplicated appendicitis, but not without controversy. A meta-analysis36 of randomised controlled trials comparing antibiotics with appendectomy has shown that although antibiotic treatment alone can be successful, patients should be made aware of a failure rate at 1 year of around 25–30% with need for readmission or surgery (table 2). A pilot randomised controlled trial suggests that this strategy might also be effective in

Future research directions

A variety of research projects for every step of the patient pathway is needed to modernise and standardise the treatment of acute appendicitis worldwide; ongoing research is shown in appendix p 4. Research relevant to both low-income and middle-income countries and high-income countries should be promoted. Both randomised and non-randomised research can promote equality of access to care and reduce variation in outcome. Correct application of technology, for both diagnosis and treatment, needs

Search strategy and selection criteria

We searched the Cochrane Library, MEDLINE, and Embase, from Jan 1, 2000, to the final search date (Feb 1, 2015). We used the search terms “appendicitis” or “acute” in combination with the terms “diagnosis” or “treatment”. We mostly selected publications from within the past 5 years, but did not exclude commonly referenced and highly regarded older publications. We also searched the reference lists of articles identified by this search strategy and selected those we judged to be relevant. We

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