Early ultrasound in acute appendicitis avoids CT in most patients but delays surgery and increases complicated appendicitis if nondiagnostic – A retrospective study

https://doi.org/10.1016/j.amjsurg.2019.05.013Get rights and content

Highlights

  • Early preoperative imaging for appendicitis is feasible in most patients.

  • US was diagnostic in 80.5%, averting the need for CT in these patients.

  • Negative/inconclusive US delays surgery and may lead to complicated appendicitis.

Abstract

Background

We determined whether increasing early imaging (in the emergency department) was associated with earlier surgery and a decrease in complicated appendicitis.

Methods

Retrospective study; 3013 operations between 12/2006–12/2016.

Results

Early imaging increased from 13.1% to 74.1%, mostly due to increasing use of ultrasound. Negative appendectomies decreased from 10.7% to 5.1% (p < 0.001). Ultrasound was diagnostic in 80.5%. The false positive rate of ultrasound was 4%. Median time to surgery following positive ultrasound was 7.4 h (IQR 5.8–9.4), shorter compared to no early imaging (13.3 h, IQR 7.2–20.0; p < 0.001). However, median time to surgery following inconclusive and negative ultrasound was 11.5 h (IQR 8.7–16.1) and 17.0 h (IQR 10.3–26.7) respectively. The incidence of complicated appendicitis was 40% and 37.7%, higher than 21.5% in patients with positive US (p < 0.001).

Conclusions

Early imaging resulted in earlier surgery but did not reduce the incidence of complicated appendicitis. Ultrasound averted the need for CT in the majority of patients. When ultrasound was negative or inconclusive, time to surgery was delayed and the rate of complicated appendicitis higher.

Introduction

Acute appendicitis is a common surgical emergency worldwide.1 The major untoward event in patients with acute appendicitis is the development of complicated appendicitis.2 Historically, difficulties in arriving at an accurate diagnosis and concerns for the development of complicated appendicitis led to liberal indications for surgery in patients with suspected appendicitis. When the decision to operate is based solely on clinical findings without imaging, the proportion of operations in which a non-inflamed appendix is encountered approximates 20%.3,4

The need to avoid unnecessary surgery together with the need to avoid delays that may lead to complications has led researchers to assess the effectiveness of imaging in the diagnosis of acute appendicitis. Computed tomography (CT) has been shown to prevent unnecessary appendectomies, but concerns have been raised due to patient exposure to ionizing radiation and nephrotoxic contrast material.5 Ultrasound (US) has become an acceptable alternative to CT as a diagnostic tool in acute appendicitis in many countries and some hospitals in the USA.6, 7, 8, 9, 10, 11, 12, 13 Pooled estimates from 25 studies shows a sensitivity of 83.7% and a specificity of 95.6% for acute appendicitis.6

Delays to diagnosis and surgery for appendicitis have previously been thought to be associated with the development of complicated appendicitis, although more recent data suggests that some patients will experience ruptured appendicitis early in the course, while others will not develop it despite delays.14,15 While the role of imaging in decreasing unnecessary appendectomies is known, the impact of imaging on complicated appendicitis has not been studied. The main aim of this study was to evaluate the impact of early imaging on time to surgery from admission and on the proportion of patients with complicated appendicitis. We hypothesized that increased use of early imaging would result in earlier surgery and fewer cases of complicated appendicitis.

Section snippets

Study design

This was a retrospective observational cohort study approved by our institutional review board in which the need for informed consent was waived (IRB protocol: 0010-13-HYMC).

Study setting and population

Included in this study were male and female emergency department patients from all ages who underwent appendectomy in a single medical center in Israel between December 1, 2006 and December 31, 2016. These dates were chosen because during this time period US was gradually introduced as an additional diagnostic tool in the

Patient population

Review of patient files identified 3137 patients who underwent appendectomy during the study period. Of these 124 patients were excluded: 82 with incidental appendectomy; 30 with interval appendectomy; 7 who failed antibiotic treatment for either acute appendicitis or periappendicular abscess; 4 who underwent prophylactic appendectomy for Familiar Mediterranean Fever; and one patient who underwent appendectomy for penetrating trauma (Fig. 1).

Three thousand thirteen patients were included in

Discussion

The need to avoid unnecessary surgery coupled with the need to avoid unnecessary delays in appropriate care has led to increased use of preoperative imaging in the diagnosis of acute appendicitis.19 We included patients having surgery from 2007 to 2016, a decade when there was a gradual increase in reliance on imaging, rather than clinical clues alone, for diagnosis. This change was due to an increase in US utilization, whether early or late, while CT scan utilization remained relatively

Conclusions

In conclusion, the results of this study indicate that early imaging results in earlier surgery but does not result in reduced incidence of complicated appendicitis. Early US averts the need for CT in most patients with acute appendicitis. US should be the first imaging modality for diagnosing acute appendicitis in most patients with suggestive symptoms and signs. A positive US should prompt urgent surgery due to its low false positive rate. Since imaging has become a cornerstone in the

Conflict of interest disclosure

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Itamar Ashkenazi reports no conflicts of interests.

Abdel-Rauf Zeina reports no conflict of interest.

Oded Olsha reports no conflicts of interest.

Sources of funding for research/publication and conflicts of interest: none to be declared

Preliminary results were presented in the European Congress of Trauma and Emergency Surgery 2015 and 2017, in the Israeli Surgical Society biannual conference 2015 and in the World Congress of Emergency Surgery 2015.

Author contributions

Study concept and design: all authors.

Acquisition, analysis, or interpretation of data: Itamar Ashkenazi, Oded Olsha.

Drafting of the manuscript: Itamar Ashkenazi, Oded Olsha.

Critical revision of the manuscript for important intellectual content: all authors.

Statistical analysis: Itamar Ashkenazi, Oded Olsha.

Final approval: all authors.

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