AA, the most common abdominal surgical emergency in pediatric surgery, is often caused by obstruction of the appendix lumen due to fecalitis or diffuse lymphoid hyperplasia, resulting in bacterial proliferation and ischemic injury (1,4). AA constitutes 25% of the causes of acute abdomen in adults whereas this rate rises to 32% in children (8).
The diagnosis of AA is mainly based on careful anamnesis and detailed physical examination. However, delays in diagnosis and treatmant may occur in children and confused patients, due to difficulties in taking medical history and physical examination (4).
High white blood cell count is an important laboratory finding that supports the diagnosis of AA. However, the sensitivity of leukocytosis was found to be between 19-60% in the previous studies (9). Due to the low sensitivity of laboratory tests, imaging methods are commonly used especially in patients with atypical clinical symptoms. Today, the most frequently used methods are abdominal US and CT.
The purpose of imaging in the diagnosis of AA is to increase the diagnostic efficiency as well as to reduce the health costs and medical risks for the patient. The use of US in the evaluation of the appendix was first described by Puylaert in 1986 (10). Due to its advantages such as not containing radiation, being available in many centers and being able to be used at the bedside, US has been the first choice among the imaging methods (11). In a comprehensive and systematic review of 18 clinical studies, 77.2% sensitivity and 60% specificity rates of abdominal US were reported in the diagnosis of AA (12). In our study, the sensitivity and specificity were calculated as 77.2% and 52.6%, respectively. In another study conducted on 238 patients, the authors reported the values of 73.6% for diagnostic accuracy, 46.1% for NPV, and 73.6% for PPV (13). In a larger study including 500 patients, PPV, NPV, and diagnostic accuracy of abdominal US were calculated as 94.03%, 13.42% and 70.06% respectively (10). In our study, the diagnostic accuracy rate of US was 70.5%, 81.2% for PPV and 46.5% for NPV, consistent with the literature.
Since the quality and accuracy of the results for US largely depend on the skill of the person performing it, great differences can be seen in the results of various studies. Therefore, this situation can be a significant disadvantage for this examination (11). In addition, the incompatibility of the child who has abdominal pain and whose communication skills are not yet well developed, the presence of gas-filled intestines in the right lower quadrant of the abdomen of obese patients, and the absence of high-resolution transducers are other disadvantages of the use of US (14).
The previous studies showed that abdominal CT can be more effective in making a timely and accurate diagnosis, since abdominal US has a wide range of sensitivity and specificity (15-17). Although it is recommended to perform the examination with contrast, it was stated that non-contrast CT examinations with appropriate cross-sections may also be sufficient for the diagnosis (15). In a study evaluated the diagnostic performance of CT imaging in children with AA, diagnostic accuracy of 95.6%, sensitivity of 97.3%, specificity of 93.7%, PPV of 89.0% and NPV of 98.7% were measured (16). In a study comparing the differences in imaging modality use and associated outcomes for AA between two pediatric hospitals in the United States and Spain, the diagnostic accuracy of abdominal CT was reported to be 94.7% and 95%, respectively (17). In our study, the sensitivity and specificity of CT in the diagnosis of AA were 88.1% and 57.1%, respectively. In addition, PPV was 88.8%, NPV was 55.1 %, and the diagnostic accuracy was 81.8%, consistent with the previous reports.
Although CT has been shown to be superior to US in the diagnosis of AA, it also has some disadvantages. For example, CT is not ubiquitous and increases the health costs. Additionally, exposure to ionizing radiation, reactions due to contrast agents, and prolongation of the time until surgery are the other disadvantages (18).
Since very serious complications can develop as a result of the delay in the diagnosis of AA, surgeons generally prefer to perform appendectomy in suspected cases. Therefore, mistakes in the diagnosis of AA cause negative appendectomy (19). Problems that may be experienced due to negative appendectomy are complications related to anesthesia, intraabdominal adhesions, and poor quality of life due to unnecessary surgery (19). Negative appendectomy rates in children have been reported between 1% and 40%, depending on the scope, size and site of the studies performed in the literature (20). In our series, our negative appendectomy rate was 14.3%.