# Evaluation of Ultrasound Accuracy in Acute Appendicitisitis Diagnosis
## 4 Discussion  
US has been touted as an examination that may help in the diagnosis of acute appendicitis in addition to physical examination [18]. Furthermore, the non-ionizing characteristics of US have led to an increased interest in exploring its diagnostic accuracy for acute appendicitis. The only drawback in the choice of US as a diagnostic strategy is the concern about its diagnostic accuracy as explored in this study. In this context, the graded compression US has been reported to demonstrate highly variable levels of accuracy. In particular, its sensitivity has been recorded as ranging  
Figure 3: Boxplot illustrating the relationship between patients’ age and image features. The black dots represent data outliers. Figure 2: Specificity readings against image features. between 44% and 100%, and its specificity between 47% and 99% [17]. However, it has also been reported that the sensitivity of US can be as high as 90% if the diagnosis is made by an individual with a high level of expertise in the field [19]. In the present study, the sensitivity of US for diagnosing acute appendicitis was 38.9%, and the specificity was 89.5%. The study also demonstrated that there was no significant association between the accuracy of US diagnosis and the years of experience of the sonographers. A mere 46.2% of the patients in this study were correctly diagnosed. According to [PERSON] et al., the appendix is not commonly visualized by US, as US demonstrates insufficient sensitivity for diagnosing appendicitis [20]. During the current study, the visualization of the appendix was not possible in 21.8% of cases, and the number of false-negative cases was 24 out of a total 31 subjects. The appendix is not detectable by US when located retroccally or deep inside the pelvis. In addition, excessive overlying bowel gas may also impede the detection of appendicitis. The diagnosis is also dependent on the expertise of the sonographer conducting the procedure [7, 21, 22]. Conversely, our findings provide no evidence that the years of experience improve sonographer's performance in diagnosing appendicitisitis. [PERSON] et al. reported that the rate of negative appendectomies is 16% [23]. This study reported a much lower rate of negative appendectomies, with only 1.4% of cases being false positives. In contrast, [PERSON] et al. reported that 2.2% of appendicitis diagnoses were false positives [22], while [PERSON] reported a figure of 4.4% [24]. Several factors can influence the acute appendicitisis diagnosis by US, the most crucial of which is the outer diameter of the vermiform appendix. In a previous study, a sensitivity of 97% and a PPV of 97% was noted when the outer diameter of the vermiform appendix was 7 mm or more; however, it also showed a high rate of false positives. Insufficient compressibility can also influence diagnosis, and levels of 85% sensitivity and 93% PPV have been reported as a result [25]. During this study, an accurate diagnosis was made using US when the diameter of the vermiform appendix was 7 mm or more, leading to a sensitivity of 74% and a PPV of 93.3% (See Figure 4a,b). The presence of free fluid also afforded a sensitivity of 53% and a PPV of 95% (See Figure 4c). The presence of free fluid is widely known as a secondary feature, and it could often be suggestive of an abdominal condition but not specific for appendicitisis [26, 27]. In this study, approximately 50% of cases presented free fluid showed an absence of a distinctly visualized appendix. Therefore, radiologists argue that the appendix must be seen to confirm the inflammation. Nevertheless, the visualization of the appendix can often be difficult. It has been found that repeating ultrasound examination for secondary features after a few hours is necessary. It significantly improved ultrasound sensitivity and patient's management [28]. Figure 4: _Cont._  
The study showed that there was no significant association between the age and sex of the patients and the accuracy of the diagnosis.