Prospective study of computed tomography in patients with suspected acute appendicitis and low Alvarado score

Computed tomography for diagnosis of acute appendicitis in adults

BACKGROUND

Diagnosing acute appendicitis (appendicitis) based on clinical evaluation, blood testing, and urinalysis can be difficult. Therefore, in persons with suspected appendicitis, abdominopelvic computed tomography (CT) is often used as an add-on test following the initial evaluation to reduce remaining diagnostic uncertainty. The aim of using CT is to assist the clinician in discriminating between persons who need surgery with appendicectomy and persons who do not.

OBJECTIVES

Primary objective Our primary objective was to evaluate the accuracy of CT for diagnosing appendicitis in adults with suspected appendicitis. Secondary objectives Our secondary objectives were to compare the accuracy of contrast-enhanced versus non-contrast-enhanced CT, to compare the accuracy of low-dose versus standard-dose CT, and to explore the influence of CT-scanner generation, radiologist experience, degree of clinical suspicion of appendicitis, and aspects of methodological quality on diagnostic accuracy.

SEARCH METHODS

We searched MEDLINE, Embase, and Science Citation Index until 16 June 2017. We also searched references lists. We did not exclude studies on the basis of language or publication status.

SELECTION CRITERIA

We included prospective studies that compared results of CT versus outcomes of a reference standard in adults (> 14 years of age) with suspected appendicitis. We excluded studies recruiting only pregnant women; studies in persons with abdominal pain at any location and with no particular suspicion of appendicitis; studies in which all participants had undergone ultrasonography (US) before CT and the decision to perform CT depended on the US outcome; studies using a case-control design; studies with fewer than 10 participants; and studies that did not report the numbers of true-positives, false-positives, false-negatives, and true-negatives. Two review authors independently screened and selected studies for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected the data from each study and evaluated methodological quality according to the Quality Assessment of Studies of Diagnostic Accuracy - Revised (QUADAS-2) tool. We used the bivariate random-effects model to obtain summary estimates of sensitivity and specificity.

MAIN RESULTS

We identified 64 studies including 71 separate study populations with a total of 10,280 participants (4583 with and 5697 without acute appendicitis). Estimates of sensitivity ranged from 0.72 to 1.0 and estimates of specificity ranged from 0.5 to 1.0 across the 71 study populations. Summary sensitivity was 0.95 (95% confidence interval (CI) 0.93 to 0.96), and summary specificity was 0.94 (95% CI 0.92 to 0.95). At the median prevalence of appendicitis (0.43), the probability of having appendicitis following a positive CT result was 0.92 (95% CI 0.90 to 0.94), and the probability of having appendicitis following a negative CT result was 0.04 (95% CI 0.03 to 0.05). In subgroup analyses according to contrast enhancement, summary sensitivity was higher for CT with intravenous contrast (0.96, 95% CI 0.92 to 0.98), CT with rectal contrast (0.97, 95% CI 0.93 to 0.99), and CT with intravenous and oral contrast enhancement (0.96, 95% CI 0.93 to 0.98) than for unenhanced CT (0.91, 95% CI 0.87 to 0.93). Summary sensitivity of CT with oral contrast enhancement (0.89, 95% CI 0.81 to 0.94) and unenhanced CT was similar. Results show practically no differences in summary specificity, which varied from 0.93 (95% CI 0.90 to 0.95) to 0.95 (95% CI 0.90 to 0.98) between subgroups. Summary sensitivity for low-dose CT (0.94, 95% 0.90 to 0.97) was similar to summary sensitivity for standard-dose or unspecified-dose CT (0.95, 95% 0.93 to 0.96); summary specificity did not differ between low-dose and standard-dose or unspecified-dose CT. No studies had high methodological quality as evaluated by the QUADAS-2 tool. Major methodological problems were poor reference standards and partial verification primarily due to inadequate and incomplete follow-up in persons who did not have surgery.

AUTHORS' CONCLUSIONS

The sensitivity and specificity of CT for diagnosing appendicitis in adults are high. Unenhanced standard-dose CT appears to have lower sensitivity than standard-dose CT with intravenous, rectal, or oral and intravenous contrast enhancement. Use of different types of contrast enhancement or no enhancement does not appear to affect specificity. Differences in sensitivity and specificity between low-dose and standard-dose CT appear to be negligible. The results of this review should be interpreted with caution for two reasons. First, these results are based on studies of low methodological quality. Second, the comparisons between types of contrast enhancement and radiation dose may be unreliable because they are based on indirect comparisons that may be confounded by other factors.

Diagnosis of Acute Appendicitis Using Clinical Alvarado Scoring System and Computed Tomography (CT) Criteria in Patients Attending Gujarat Adani Institute of Medical Science - A Retrospective Study

Background

The aim was to evaluate the clinical Alvarado scoring system and computed tomography (CT) criteria for the diagnosis of acute appendicitis.

Material/Methods

The study was carried out retrospectively in patients who were referred to the Institute between March 2014 and January 2015. One hundred seventeen patients with acute abdominal pain who underwent abdominal CT were enrolled in this retrospective study. Patient demographics, clinical Alvarado scoring, CT images, and pathologic results of the patients were evaluated.

Results

Thirty nine of the 53 patients who were operated on had pathologically proven acute appendicitis. CT criteria of appendiceal diameter, presence of periappendiceal inflammation, fluid, appendicoliths, and white blood cell count (WBC) were significantly correlated with the inflammation of the appendix. The optimal cut-off value of the appendiceal diameter was 6.5 mm. The correlation between appendiceal diameter and WBC was 80% (P=0.01 <0.05). The correlation between appendiceal diameter and Alvarado score was 78.7% (P=0.01 <0.05).

Conclusions

Presence of appendiceal diameter above 6.5 mm on CT, periappendiceal inflammation, fluid, and appendicoliths should prompt the diagnosis of acute appendicitis. Since patients with acute appendicitis may not always show the typical signs and symptoms, CT is a helpful imaging modality for patients with relatively low Alvarado scores and leukocytosis, when physical examination is confusing.

Evaluation of Clinical Alvarado Scoring System and CT Criteria in the Diagnosis of Acute Appendicitis

Aim. The aim was to evaluate the clinical Alvarado scoring system and computed tomography (CT) criteria for the diagnosis of acute appendicitis. Material and Methods. 117 patients with acute abdominal pain who underwent abdominal CT were enrolled in this retrospective study. Patient demographics, clinical Alvarado scoring, CT images, and pathologic results of the patients were evaluated. Results. 39 of the 53 patients who were operated on had pathologically proven acute appendicitis. CT criteria of appendiceal diameter, presence of periappendiceal inflammation, fluid, appendicolith, and white blood cell (WBC) count were significantly correlated with the inflammation of the appendix. The best cut-off value for appendiceal diameter was 6.5 mm. The correlation between appendiceal diameter and WBC count was 80% (P = 0.01 < 0.05). The correlation between appendiceal diameter and Alvarado score was 78.7% (P = 0.01 < 0.05). Conclusion. Presence of CT criteria of appendiceal diameter above 6.5 mm, periappendiceal inflammation, fluid, and appendicolith should prompt the diagnosis of acute appendicitis. Since patients with acute appendicitis may not always show the typical signs and symptoms, CT is a helpful imaging modality for patients with relatively low Alvarado score and leukocytosis and when physical examination is confusing.

Nonoperative treatment of acute appendicitis in children: A feasibility study

PURPOSE

Nonoperative treatment of acute appendicitis appears to be feasible in adults. It is unclear whether the same is true for children.

METHODS

Children 5-18 years with <48 h symptoms of acute appendicitis were offered nonoperative treatment: 2 doses of piperacillin IV, then ampicillin/clavulanate ×1 week. Treatment failure (worsening on therapy) and recurrence (after completion of therapy) were noted. Patients who declined enrollment were asked to participate as controls. Cost-utility analysis was performed using Pediatric Quality of Life Scale (PedsQL®) to calculate quality-adjusted life month (QALM) for study and control patients.

RESULTS

Twenty-four patients agreed to undergo nonoperative management, and 50 acted as controls. At a mean follow-up of 14 months, three of the 24 failed on therapy, and 2/21 returned with recurrent appendicitis at 43 and 52 days, respectively. Two patients elected to undergo an interval appendectomy despite absence of symptoms. Appendectomy-free rate at one year was therefore 71% (C.I. 50-87%). No patient developed perforation or other complications. Cost-utility analysis shows a 0.007-0.03 QALM increase and a $1359 savings from $4130 to $2771 per nonoperatively treated patient.

CONCLUSION

Despite occasional late recurrences, antibiotic-only treatment of early appendicitis in children is feasible, safe, cost-effective and is experienced more favorably by patients and parents.

Journal Club: the Alvarado score as a method for reducing the number of CT studies when appendiceal ultrasound fails to visualize the appendix in adults

OBJECTIVE. The purpose of this article is to evaluate the hypothesis that Alvarado scores of 3 or lower identify adult patients who are unlikely to benefit from CT after appendiceal ultrasound fails to show the appendix and is otherwise normal. MATERIALS AND METHODS. We identified 119 consecutive adults for whom the appendix was not seen on otherwise normal appendiceal sonography performed as the first imaging study for suspected appendicitis, who subsequently underwent CT within 48 hours, and whose data permitted retrospective calculation of admission Alvarado scores. Specific benefits of CT were defined as diagnoses of appendicitis or significant alternative findings, and specific benefits were compared between patients with Alvarado scores of 3 or less and 4 or higher. Significant alternative findings on CT were findings other than appendicitis that were treated with medical or surgical therapy during the admission or that were to be addressed during follow-up care. Diagnostic reference standards were discharge diagnoses, pathologic examinations, and clinical follow-up. RESULTS. No patients (0.0%, 0/49) with Alvarado scores 3 or lower had appendicitis, compared with 17.1% (12/70) of patients with Alvarado scores 4 or higher (p = 0.001), and CT showed neither appendicitis nor significant alternative findings in 85.7% (42/49) versus 58.6% (41/70) of these patients, respectively (p = 0.002). The rates of perforated appendicitis, as well as significant alternative CT findings, did not differ significantly. CONCLUSION. Adults with Alvarado scores 3 or lower who have nonvisualized appendixes and otherwise normal appendiceal sonography are at very low risk for appendicitis or significant alternative findings and therefore are not likely to benefit from CT.

Comparison of multislice computed tomography and clinical scores for diagnosing acute appendicitis

Objective

To compare Raja Isteri Pengiran Anak Saleha Appendicitis (RIPASA) and Alvarado scores with multislice computed tomography (MSCT) for diagnosing acute appendicitis (AA).

Methods

This retrospective study included patients with abdominal pain who had undergone MSCT, and whose medical notes included RIPASA and Alvarado score parameters. MSCT was compared with RIPASA and Alvarado scores for diagnosing AA.

Results

Of 297 patients included, sensitivity, specificity and accuracy for diagnosing AA were 95.2%, 73.6% and 87.2% for RIPASA score (cutoff value 7.5) and 63.1%, 80.9% and 69.7% for Alvarado score (cutoff value 7). Sensitivity, specificity and accuracy of MSCT for diagnosing AA were 98.9%, 96.4% and 98.0%, respectively. In terms of accuracy, statistically significant differences were observed between RIPASA and Alvarado scores, and between MSCT and RIPASA scores. The mean RIPASA score was significantly different in the simple AA group (9.7 ± 2.2) compared with other AA groups (10.5 ± 1.7). No statistically significant difference was observed in RIPASA score between nonperforated and perforated AA. MSCT sensitivity, specificity and accuracy for diagnosing simple AA were 94.1%, 96.4% and 95.8%, respectively; for differentiating perforated and nonperforated AA, scores were 90.2%, 95.2% and 94.1%, respectively.

Conclusion

MSCT is the optimum diagnostic tool for AA, followed by RIPASA score and Alvarado score, particularly in diagnosing simple and perforated AA.

Cost-effectiveness of diagnostic approaches to suspected appendicitis in children

BACKGROUND

Our group recently published a clinical pathway (Le Bonheur Clinical Pathway [LeB-P]) that used the Samuel Pediatric Appendicitis Score with selective use of ultrasonography (USG) for diagnosis of children at risk for appendicitis. The objective of this study was to model the cost-effectiveness of implementing the LeB-P compared with usual care.

STUDY DESIGN

We constructed a decision analytic model comparing hospital costs for the following diagnostic strategies for suspected appendicitis: emergency department clinician judgment alone, USG on all patients, CT on all patients, overnight observation with surgical evaluation without studies, and the LeB-P. Prevalence of disease, outcomes probabilities, and hospital and professional costs for each option were derived from published literature, national cost data, and our previous study results. Cost-effectiveness was calculated using these 3 sets of parameters.

RESULTS

In the base case model, USG was the preferred strategy over LeB-P and overnight observation with surgical evaluation without studies. Emergency department clinician judgment alone and CT were dominated by the other pathways, based on either lower diagnostic accuracy or increased costs. Compared with LeB-P, USG costs $337 less per patient evaluated, but increased the diagnostic error rate by 2%. Using LeB-P rather than USG would cost an institution an additional $17,206 to eliminate one misdiagnosis, which is known as the incremental cost-effectiveness ratio.

CONCLUSIONS

Although performing USG on all children with suspected appendicitis was determined to be the most cost-effective strategy, using the Pediatric Appendicitis Score with selective use of USG (LeB-P) improved diagnostic accuracy at a moderate increase in cost and decreased CT use.

Prospective evaluation of a clinical pathway for suspected appendicitis

OBJECTIVE

To evaluate the diagnostic accuracy of a clinical pathway for suspected appendicitis combining the Samuel's pediatric appendicitis score (PAS) and selective use of ultrasonography (US) as the primary imaging modality.

METHODS

Prospective, observational cohort study conducted at an urban, academic pediatric emergency department. After initial evaluation, patients were determined to be at low (PAS 1-3), intermediate (PAS 4-7), or high (PAS 8-10) risk for appendicitis. Low-risk patients were discharged with telephone follow-up. High-risk patients received immediate surgical consultation. Patients at intermediate risk for appendicitis underwent US.

RESULTS

Of the 196 patients enrolled, 65 (33.2%) had appendicitis. An initial PAS of 1-3 was noted in 44 (22.4%), 4-7 in 119 (60.7%), and 8-10 in 33 (16.9%) patients. Ultrasonography was performed in 128 (65.3%) patients, and 48 (37.5%) were positive. An abdominal computed tomography scan was requested by the surgical consultants in 13 (6.6%) patients. The negative appendectomy rate was 3 of 68 (4.4%). Follow-up was established on 190 of 196 (96.9%) patients. Overall diagnostic accuracy of the pathway was 94% (95% confidence interval [CI] 91%-97%) with a sensitivity of 92.3% (95% CI 83.0%-97.5%), specificity of 94.7% (95% CI 89.3%-97.8%), likelihood ratio (+) 17.3 (95% CI 8.4-35.6) and likelihood ratio (-) 0.08 (95% CI 0.04-0.19).

CONCLUSIONS

Our protocol demonstrates high sensitivity and specificity for diagnosis of appendicitis in children. Institutions should consider investing in resources that increase the availability of expertise in pediatric US. Standardization of care may decrease radiation exposure associated with use of computed tomography scans.

Different urinalysis appearances in children with simple and perforated appendicitis

PURPOSE

This study aimed to determine whether routine urinalysis may serve as a tool in discriminating between acute appendicitis and perforated appendicitis in children.

BASIC PROCEDURES

We prospectively collected 357 patients with clinically suspected acute appendicitis. Urinalysis was performed in patients with clinically suspected acute appendicitis before surgical intervention. Routine urinalysis is composed of 2 examinations: chemical tests for abnormal chemical constituents and microscopic tests for abnormal insoluble constituents. Receiver operating characteristic curves for urine white blood cell (WBC) counts and urine red blood cell (RBC) counts in distinguishing between patients with simple appendicitis and patients with perforated appendicitis were also analyzed.

MAIN FINDINGS

Urine ketone bodies, leukocyte esterase, specific gravity, pH, WBC, and RBC counts were all significant parameters among patients with normal appendices, simple appendicitis, and perforated appendicitis (all P < .05). Based on multivariate logistic regression analysis, positive urine ketone bodies and nitrate were significant parameters in predicting perforated appendicitis (P = .002 and P = .008, respectively). According to the results of receiver operating characteristic curves, the appropriate cutoff values were 2.0/high-power field for urine RBC counts and 4.0/high-power field for urine WBC counts in predicting perforated appendicitis in children.

PRINCIPAL CONCLUSIONS

Routine urinalysis may serve to aid in discriminating between simple and perforated appendicitis. Clinically, we believe that these urine parameters may aid primary emergency physicians with decision making in patients with clinically suspected appendicitis.