Improving the diagnostic accuracy of ultrasonography in suspected acute appendicitis by the combined transabdominal and transvaginal approach

ACR Appropriateness Criteria® Right Lower Quadrant Pain: 2022 Update

This document focuses on imaging in the adult and pregnant populations with right lower quadrant (RLQ) abdominal pain, including patients with fever and leukocytosis. Appendicitis remains the most common surgical pathology responsible for RLQ abdominal pain in the United States. Other causes of RLQ pain include right colonic diverticulitis, ureteral stone, and infectious enterocolitis. Appropriate imaging in the diagnosis of appendicitis has resulted in decreased negative appendectomy rate from as high as 25% to approximately 1% to 3%. Contrast-enhanced CT remains the primary and most appropriate imaging modality to evaluate this patient population. MRI is approaching CT in sensitivity and specificity as this technology becomes more widely available and utilization increases. Unenhanced MRI and ultrasound remain the diagnostic procedures of choice in the pregnant patient. MRI and ultrasound continue to perform best in the hands of the experts. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

NSQIP Based Predictors of False Negative and Indeterminate Ultrasounds in Adults With Appendicitis

BACKGROUND

It has been well established that ultrasound (US) is the initial screening tool for children with suspected acute appendicitis. However, computed tomography (CT) has become the standard screening modality for adults presenting with abdominal pain. A recent review of National Surgical Quality Improvement Program (NSQIP) data revealed US is being utilized as a screening modality in adults. We aimed to assess the diagnostic performance of US in evaluating adults with acute appendicitis.

STUDY DESIGN

The American College of Surgeons NSQIP and NSQIP Procedure Targeted Data Files were accessed and examined for all patients in 2016 and 2017 who received an US and underwent an appendectomy. The US results were then correlated to the pathology in order to determine the diagnostic performance. Additionally, we identified predictors for indeterminate and false negative US results.

RESULTS

Our study included 3607 appendectomy patients of which 1135 (30%) had an indeterminate US, 683 (18%) had an US not consistent with appendicitis, and 1789 (49%) had an US consistent with appendicitis. Sensitivity and Specificity were 74.3% and 53.0%, respectively. Positive Predictive Value (PPV) and Negative Predictive Value (NPV) were 95.9% and 12.2%, respectively. On regression analysis, clinically relevant predictors for false negative and indeterminate studies included age, sex, and BMI.

CONCLUSIONS

Ultrasound is an effective initial imaging modality for acute appendicitis in the adult population. Females, age >30 y, and elevated BMI were more likely to have indeterminate or false negative results. These patients may benefit from CT as their initial screening test.

The Borderline-Size Appendix: Grayscale, Color Doppler, and Spectral Doppler Findings That Improve Specificity for the Sonographic Diagnosis of Acute Appendicitis

Diagnostic criteria for acute appendicitis using graded compression sonography have been well established based on the maximum outer diameter (MOD) of the appendix, with MOD values of <6 mm nearly always indicating normal appendices and MOD values of >8 mm nearly always indicating appendicitis. However, the "borderline-size" appendix, meaning one whose MOD lies between these ranges (ie, an appendix with MOD of 6-8 mm), presents a diagnostic dilemma because appendices in this size range are neither clearly normal nor abnormal when diagnosis is based on the MOD alone; accordingly, such borderline MOD values are diagnostically equivocal, and sonographic diagnosis must rely on sonographic findings other than the MOD. The goal of this review was to examine the additional sonographic findings that can add specificity and help enable an accurate diagnosis to be made in patients with borderline-size appendices.

ACR Appropriateness Criteria® Right Lower Quadrant Pain-Suspected Appendicitis

Appendicitis remains the most common surgical pathology responsible for right lower quadrant (RLQ) abdominal pain presenting to emergency departments in the United States, where the incidence continues to increase. Appropriate imaging in the diagnosis of appendicitis has resulted in decreased negative appendectomy rate from as high as 25% to approximately 1% to 3%. Contrast-enhanced CT remains the primary and most appropriate imaging modality to evaluate this patient population. MRI is approaching CT in sensitivity and specificity as this technology becomes more widely available and utilization increases. Unenhanced MRI and ultrasound remain the diagnostic procedures of choice in the pregnant patient. MRI and ultrasound continue to perform best in the hands of experts. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The evolving management of the appendix mass in the era of laparoscopy and interventional radiology

AIM

An appendix mass is the result of a walled-off perforation of the appendix which localises, resulting in a mass and it is encountered in up to 7% of patients presenting with acute appendicitis. However, its management is controversial due to the lack of high level evidence. This review article sets out a rationale diagnostic and therapeutic strategy for the appendix mass based upon up-to-date available evidence.

METHODS

A literature review of the investigation and management of appendix mass/complicated appendicitis was undertaken using PubMed, EMBASE and Google Scholar.

RESULTS/CONCLUSION

No prospective studies were identified. The great majority of recent evidence supports a conservative management approach avoiding urgent appendicectomy because of the high risk of major complications and bowel resection. Appendix abscesses over 5 cm in diameter and persistent abscesses should be drained percutaneously along with antibiotics. Appendix phlegmon should be treated with antibiotics alone. Surgery is reserved for patients who fail conservative treatment. Routine interval appendicectomy is not recommended, but should be considered in the context of persistent faecolith, ongoing right iliac fossa pain, recurrent appendicitis and appendix mass persistent beyond 2 weeks. Clinicians should be particularly wary of patients with appendix mass aged over 40 and those with features suggesting malignancy.

Diagnostic Imaging of Appendicitis With Supplementation by Transabdominal and Transvaginal Sonography

Acute appendicitis is a condition that can affect any member of the population. Without timely treatment there is a high likelihood of rupture leading to peritonitis, and early diagnosis is imperative to obtaining treatment. Sonography can be used without fear of radiation exposure to the patient and with relatively little discomfort, ideal for pediatric patients. It can also be used with little patient preparation, with the possibility of a more rapid diagnosis than other imaging modalities. For patients presenting with atypical symptoms, sonography may be used to increase diagnostic accuracy, which will lead to a drop in the surgical removal rate of a healthy appendix. When diagnostic criteria are met, sonography results can be correlated with the patient’s blood test and clinical symptoms to make a positive diagnosis. The addition of the transvaginal approach for female patients has further increased the rate of success of diagnosing acute appendicitis, so that appropriate emergent surgery can be done.

Sonography of the normal appendix: its varied appearance and techniques to improve its visualization

The sonographic identification of the normal appendix is crucial to the success of ultrasound as an effective screening method for diagnosing acute appendicitis. The normal appendix can be challenging to identify on sonography, however, because it is a narrow tubular structure and has variable sonographic appearances. Moreover, the tip of the appendix can be quite variable in location. In this article, we review the various sonographic appearances of the normal appendix and highlight strategies to improve its visualization.

The role of US examination in the management of acute abdomen

Acute abdomen is a medical emergency, in which there is sudden and severe pain in abdomen of recent onset with accompanying signs and symptoms that focus on an abdominal involvement. It can represent a wide spectrum of conditions, ranging from a benign and self-limiting disease to a surgical emergency. Nevertheless, only one quarter of patients who have previously been classified with an acute abdomen actually receive surgical treatment, so the clinical dilemma is if the patients need surgical treatment or not and, furthermore, in which cases the surgical option needs to be urgently adopted. Due to this reason a thorough and logical approach to the diagnosis of abdominal pain is necessary. Some Authors assert that the location of pain is a useful starting point and will guide a further evaluation. However some causes are more frequent in the paediatric population (like appendicitis or adenomesenteritis) or are strictly related to the gender (i.e. gynaechologic causes). It is also important to consider special populations such as the elderly or oncologic patients, who may present with atypical symptoms of a disease. These considerations also reflect a different diagnostic approach. Today, surely the integrated imaging, and in particular the use of multidetector Computed Tomography (MDCT) has revolutionised the clinical approach to this condition, simplyfing the diagnosis but burdening the radiologists with the problems related to the clinical management. However although CT emerging as a modality of choice for evaluation of the acute abdomen, ultrasonography (US) remains the primary imaging technique in the majority of cases, especially in young and female patients, when the limitation of the radiation exposure should be mandatory, limiting the use of CT in cases of nondiagnostic US and in all cases where there is a discrepancy between the clinical symptoms and negative imaging at US.