Authors: Ayushi Vig, Arvind Sinha, Taruna Yadav, Shreyas Krishnamurthy, Somya Bhatt, Kirtikumar J. Rathod, Manish Pathak, Rahul Saxena, Pushpinder Singh Khera
Categories: Original Article
Source: Journal of Indian Association of Pediatric Surgeons
Acute appendicitis is a common surgical emergency in children, often requiring imaging for confirmation due to diverse presentations. While computed tomography scan is favored in many centers for its sensitivity, it comes with radiation exposure and higher costs. Ultrasonography, being radiation-free and cost-effective, is gaining popularity, especially in pediatric cases. However, its reported accuracy varies in the literature. This study aims to evaluate the diagnostic accuracy of ultrasonography in pediatric appendicitis cases and to determine its precision in distinguishing between simple and complicated cases of appendicitis.
A retrospective analysis was conducted on children with suspected appendicitis who presented to the department of pediatric surgery. All patients underwent ultrasonography followed by appendicectomy based on considered clinical decision. Ultrasonography findings were compared with intraoperative observations categorized as uncomplicated or complicated appendicitis.
Among 152 patients, ultrasonography accurately diagnosed appendicitis in 94.6% of cases, with 5.38% having nonvisualized appendices. In our group, the sensitivity and specificity of ultrasound to detect appendicitis were 94.62% and 95.65%, respectively. The diagnostic accuracy of the test is 95.63%. However, in our study, the sensitivity of the ultrasonography to correctly identify if it is a simple or complicated appendicitis was only 54.9% but had a specificity of 98.7%. Thus, ultrasonography showed a much lower sensitivity (54.9%) in distinguishing between simple and complicated appendicitis.
Ultrasonography demonstrates high sensitivity and specificity in diagnosing pediatric appendicitis, making it a promising preoperative investigation. However, it may not accurately differentiate between simple and complicated cases. A comprehensive approach involving clinical and laboratory parameters alongside secondary imaging may be necessary for accurate diagnosis, especially in cases of perforated appendicitis.
KEYWORDS: Accuracy, appendicitis, children, pediatric, ultrasound
Appendicitis is the most prevalent surgical emergency in children.[1] Imaging is a useful auxiliary method, even if history and examination are the mainstays of diagnosis. Despite the existence of several clinical scales for accurate diagnosis, the diverse presentations of appendicitis and diagnostic dilemmas often necessitate imaging to confirm clinical suspicion. Ultrasonography and computed tomography (CT) scan of the abdomen are the two most utilized investigations for evaluating patients presenting with right iliac fossa pain.
CT scan is the preferred diagnostic tool in pediatric centers across North America and in most centers for adults to evaluate right iliac fossa pain due to its high sensitivity and specificity. CT scan of the abdomen has the problem of ionizing radiation along with a higher cost and a requirement for a higher level of expertise and infrastructure to diagnose the condition accurately. Given the above, many centers favor abdominal ultrasonography as the first-line imaging modality for diagnosing appendicitis in pediatric patients.[2] This variation in the algorithm is feasible as the sensitivity of ultrasonography is reported to be higher in children compared to adults. Moreover, it avoids radiation exposure for children and minimizes the financial burden on healthcare facilities.[3] However, the accuracy of ultrasonography as a diagnostic investigation ranges from 72.5% to 96% in the available literature. The objective of the current study is to evaluate the diagnostic accuracy of ultrasonography in our institution and to validate its findings with intraoperative observations in pediatric patients.
All patients who presented to the outpatient department or the hospital emergency department with right iliac fossa pain were included in the study. The study period was over four years, from January 2020 to December 2023 over a period of 4 years. We performed a retrospective analysis of all children who presented with right iliac fossa pain and were suspected as cases of appendicitis based on clinical examination at our institute. All patients presenting with clinical features suggestive of acute appendicitis underwent laboratory investigations and initial imaging with ultrasonography. Medical records were analyzed to assess ultrasonography findings, type of operative procedure performed, and intraoperative observations. Ultrasonography findings were categorized as uncomplicated appendicitis, complicated appendicitis, and equivocal results. Equivocal results, as far as this study was concerned, were considered if the ultrasound reported nonvisualization of the appendix and/or any alternate pathology. Positive ultrasonography findings for uncomplicated appendicitis included a noncompressible appendix with an outer diameter of more than 6mm, an appendicolith, the presence of an appendicolith, hyperechoic periappendiceal fat, and increased blood flow to the appendix on Doppler. Perforated appendicitis was diagnosed based on the visualization of a visible breach in the wall of the appendix with echogenic periappendiceal fluid or the presence of echogenic collection in the pelvis.[4] Ultrasound scan was documented to be equivocal if the appendix was not visualized which may be due to an appendix that is perforated, retrocecal, and embedded in the wall of the cecum or may be hidden in a collection. As per institutional protocol, all patients underwent appendicectomy based on the surgeon’s clinical suspicion, laboratory parameters (total leukocyte count and hs-C-reactive protein [hsCRP]), and imaging findings. Complicated or simple appendicitis based on imaging is not a factor influencing our decision to operate. Ultrasonography findings were then retrospectively corroborated with the intraoperative findings. According to intraoperative observations, uncomplicated appendicitis was defined as an inflamed phlegmonous appendix without any evidence of perforation or necrosis. Complicated appendicitis is a periappendicular abscess or a perforated or necrotic appendicitis with localized or generalized pyoperitoneum.[5]
A total of 152 patients’ children (age <18 years) with right iliac fossa pain and clinical suspicion of acute appendicitis were included in the study. The age group ranged from 2 to 17 years (mean age – 9.5 years ± 3.5 years). All patients underwent ultrasonography as the primary preoperative imaging investigation. Ultrasonography was performed mostly by on-duty residents or trainee doctors, supplemented by consultants in difficult cases, at the department of radiodiagnosis as per institutional protocol. Twenty-two patients who were suspected to have appendicitis on clinical examination had alternate pathology on imaging. The dominant diagnoses were mesenteric lymphadenitis, Meckel’s diverticulum, and renal calculi were diagnosed on imaging. The rest of the patients, i.e., a total of 130 patients, underwent laparoscopic appendicectomy between 2020 and 2023 at our institution. None of the patients underwent conservative management of appendicitis. The operative decision was based on clinical suspicion and laboratory parameters unless a definite unequivocal alternative diagnosis was forwarded on sonographic findings. Among all patients who underwent appendicectomy, 77 (59.23%) patients had intraoperative features of uncomplicated appendicitis and 53 (40.77%) patients had complicated appendicitis with localized or generalized peritonitis on exploration. None of the patients underwent a computerized tomography in the study.
The ultrasound evaluation was then evaluated and compared to the intraoperative findings. As our study is of retrospective nature, we did not have records of histopathology reports of few patients, thus we have used intraoperative findings for confirmation of appendicitis. Among the cohort of 130 patients undergoing appendicectomy, the appendix was confidently visualized in preoperative ultrasonography, and a diagnosis of acute appendicitis was made in 123 (94.6%) patients based on ultrasonographic examination. There were no negative appendicectomies in this cohort. In seven (5.38%) patients, the ultrasonologist was unable to visualize the appendix. Six out of these seven patients were found perforated on operative evaluation, and one child was noted to have acute uncomplicated appendicitis on intraoperative findings. Out of the 130 patients who underwent appendicectomy, preoperative ultrasonography accurately diagnosed complicated and uncomplicated appendicitis in 104 patients (80%). Nineteen patients in which preoperative scans reported uncomplicated acute appendicitis had perforated appendicitis intraoperatively [Table 1].
The intraoperative evaluation of the appendix was taken as the gold standard for the diagnosis of appendicitis. Since the ultrasonography and appendicectomy were performed on the same set of patients, paired data results were utilized and Chi-square test with correlated outcomes was utilized using the Statistical Package for the Social Sciences. IBM Statistical Package for the Social Sciences (SPSS), version number 28 (IBM Corp. (2020). IBM SPSS Statistics for Windows, Version 28.0. IBM Corp.)
The diagnostic accuracy of ultrasound was determined by analyzing overall accuracy, sensitivity, and specificity. These test characteristics were calculated using conventional formulae with 95% confidence intervals (95% CI). The sensitivity of ultrasonography to detect appendicitis was 94.62% in our group (89.22%–97.81%, 95% CI). The specificity of Ultrasonography (USG) in diagnosing acute appendicitis in our cohort was 95.65% (78.05%–99.89%, 95% CI). The diagnostic accuracy of the test is 95.63% (91.07%–98.27%, 95% CI).
Beyond the accuracy of ultrasonography in correctly identifying appendicitis, we sought to ascertain the accuracy of ultrasonography in correctly identifying and differentiating between simple and complicated appendicitis. However, in our study, the sensitivity of ultrasonography to correctly identify if it is a simple or complicated appendicitis was only 54.9% (40.34%–68.87%), and specificity was 98.7% (92.98%–99.97%, 95% CI). The positive predictive value for diagnosing complicated appendicitis on ultrasonography was 96.67% (80.29%–99.52%, 95% CI), and the negative predictive value was 76.13% (70.18%–81.21%, 95% CI). The test’s overall accuracy in detecting the appendix’s perforation preoperatively is 80.87% (72.98%–87.29%, 95% CI) [Table 2]. This is because, out of the total 53 cases which were found to have complicated appendicitis intraoperatively, only 28 were correctly diagnosed by ultrasonography. In 19 cases, the appendix was reported as inflamed but not perforated, and in 6 cases, the appendix was not visualized preoperatively.
The paradigm shift toward utilizing ultrasonography as the primary imaging modality for suspected appendicitis in pediatric patients underscores a transformative approach in clinical management. With its advantages of being cost-effective, noninvasive, and widely accessible, ultrasonography has become an integral part of the diagnostic algorithm for appendicitis.[6] The American College of Radiology (ACR) Appropriateness Criteria advocates ultrasonography to be the preferred investigation, providing a diagnostic benefit in pediatric patients with suspected appendicitis.[7] Owing to the combined accuracy of clinical examination, ultrasonography, and biochemical investigations, the acceptable rates of negative appendicectomy have reduced from 25% to <5%.[6,8,9] Such a substantial decrease in unnecessary surgeries not only mitigates the risks and costs associated with surgical interventions but also significantly improves patient outcomes by preventing unwarranted morbidity and potential complications.
Despite being preferred as the first-line investigation for diagnosing appendicitis, the sensitivity of ultrasonography has been reported to be widely variable among various studies. In a 2013 multicentric cohort study performed on 2625 patients, the sensitivity of ultrasonography was reported to be only 72.5%.[10] However, in 2023, Sung Uk Cho et al. performed a systematic review of the role of point-of-care ultrasound and reported a sensitivity of 91.7% and a specificity of 90.9%.[11] A meta-analysis performed by Doria et al. to identify the preferred imaging investigation for diagnosing appendicitis in children and adults reported that the sensitivity of ultrasonography is higher in children (86%–88%) compared to adults (78%–83%).[3] A recent review in the year 2024 of 8555 ultrasonographic examinations yielded an overall diagnostic accuracy of 96%, a sensitivity of 96.2%, and a specificity of 96.1%.[12] Our results are at par with this multicentric trial. Our study’s sensitivity, specificity, and accuracy are 94.62%, 95.65%, and 95.63%, respectively. The cause for this wide variation in the sensitivity of ultrasonography is attributed to operator dependency and the varied ability of the sonologist to visualize the appendix. Reported visualization rates range from 98% to 22%. However, in our institution, emergency ultrasonography is routinely performed by radiologists under training (as per institutional protocol) and has been shown to have a very high accuracy. Ultrasonography is an observer-dependent investigation, and the radiologist’s experience is believed to be pivotal in detecting appendicitis. However, we see that there is a growing trend toward a higher diagnostic yield by ultrasonography with the increasing appreciation of the specific radiological signs of appendicitis.
Seven of our patients had a nonvisualized appendix on ultrasound examination. According to the study by Steve M de Castro et al., no visualization of the appendix is more likely to be reported in patients presenting with perforated appendicitis.[13] We found comparable results, as 6 out of 7 patients with a nonvisualized appendix on ultrasonography exhibited intraoperative evidence of perforation.
The negative predictive value of ultrasonography has also been evaluated. In a retrospective study of 193 patients undergoing ultrasonography, appendicitis was ruled out in 144 patients. They concluded that the negative predictive value of ultrasonography was 95.1%.[14] Although CT scans had a higher diagnostic performance as an investigation, the lack of radiation and reasonably high sensitivity makes ultrasonography the preferred investigation in children.[3] However, ultrasound is reported to be inferior to a CT scan with respect to concerning sensitivity and negative predictive value.[13] Thus, it may not be as useful an investigation to confidently exclude appendicitis. According to the ACR appropriateness criteria, when history and clinical examination strongly suggests appendicitis but ultrasound results are inconclusive, the next preferred investigation is CT Abdomen and Pelvis, which offers diagnostic advantages.[7] Srinivasan et al. stated that CT offers the greatest diagnostic benefit in patients in whom ultrasonography is equivocal and the Alvarado score is ≥6.[15] Krishnamoorthi et al. utilized ultrasonography as the initial imaging modality and CT in equivocal cases and stated a sensitivity and specificity of 99% and 91%, respectively.[16] Thirumoorthi et al. achieved 94% sensitivity and 98% specificity for a similar staged approach.[17] According to a Cochrane review, nonenhanced CT has a lower sensitivity of diagnosing appendicitis when compared to contrast-enhanced CT scans. However, using different types of contrast materials like intravenous along with oral or rectal contrast does not alter the accuracy of the test.[18]
As per our findings, ultrasonography is a great tool to identify acute appendicitis. However, regarding the differentiation between simple and complicated appendicitis, ultrasonography might not be an accurate investigation to make that distinction. The sensitivity of ultrasonography to correctly identify complicated appendicitis was only 54.9%. These results align with the previously reported literature. Nijssen et al., in 2021, reported a sensitivity of 46% for ultrasonography in identifying perforated appendicitis.[19] At our hospital, all patients diagnosed with appendicitis undergo appendicectomy as an institutional protocol. However, many centers may opt for a more conservative approach toward uncomplicated appendicitis. Relying solely on ultrasonographic imaging for conservative versus operative decisions would likely result in a higher rate of conservative management with its attendant complications due to missing out on perforated appendicitis on ultrasonography.[20,21] In a scenario where the accurate distinction between simple and complicated appendicitis is critical to planning further management approaches, secondary imaging modalities such as CT scans or relying on laboratory parameters might be the way to go. Laboratory parameters such as total leukocyte count and hsCRP values, when combined with imaging findings have exhibited improved sensitivity and specificity in predicting perforation in cases of appendicitis.[22]
Point-of-care ultrasonography demonstrates high sensitivity and specificity in diagnosing appendicitis in pediatric patients presenting with right iliac fossa pain. Given its high accuracy, no radiation exposure, and low-cost, ultrasonography is a promising candidate to be recognized as the gold standard preoperative investigation for diagnosing appendicitis in children. However, for an accurate preoperative diagnosis of perforated appendicitis, ultrasonography alone may not be sufficient. In those situations, a comprehensive approach, including clinical findings, biochemical investigations, and secondary imagining modalities, may be necessary to ensure an accurate diagnosis of preoperative perforation in appendicitis.
Nil.
There are no conflicts of interest.