Letter to the Editor: Diagnostic Accuracy of Alvarado Score,Laboratory Data,and CT Findings for Acute Appendicitis in Children with a Non-Diagnostic Ultrasound

Abstract

To the Editor:

Acute appendicitis (AA) in childhood is usually a challenging diagnosis, needing meticulous examination of clinical, laboratory, and radiological data.^1,2 Ultrasound (US) has been shown to be highly reliable and accurate for the diagnosis of AA in children.³ However, non-diagnostic US in a child with suspected AA is usually a challenge for the emergency physician.⁴ The surgeon is therefore faced with the difficult decision of ordering an abdominal CT scan, at the cost of radiation exposure, proceeding with surgery, with the risk of a negative appendectomy, or keeping the patient under observation on an inpatient or outpatient basis. The aim of this study was to investigate the diagnostic accuracy of Alvarado score, laboratory data and computed tomography (CT) findings for appendicitis in children with a non-diagnostic ultrasound.

After approval by the institutional review board, we conducted a retrospective study in a pediatric emergency department from January 1, 2020 to December 31, 2023. All children under 18 years of age with suspected AA and a non-diagnostic US were included. The Alvarado score,⁵ was computed for all patients. The pediatric surgeon decided whether or not to order a CT scan.

A total of 214 patients were included in this study. The mean age was 9.4 ± 2.7 years, with 48.6% (n = 104) being male. The Alvarado score was below 5 in 50.5% of patients (n = 108), equal to 5 or 6 in 37.4% (n = 80), and above 6 in 12.1% (n = 26). The mean white blood cell count and C-reactive protein (CRP) level were 12.6 ± 6.3 x10⁹/L and 51.1 ± 20.7 mg/L, respectively. Among the 214 patients, 69 (32.2%) underwent appendectomy. Among these 69 children, 62 (89.8%) had their diagnosis of appendicitis confirmed by pathological examination. Abdominal CT scans were performed in 52 (24.3%) patients. Positive CT findings were recorded in 29 patients, 22 of whom underwent surgery. Of these 22 patients, a final diagnosis of appendicitis was made in 21. Of the 23 patients with a negative CT result, no patient underwent surgery and none was diagnosed with acute appendicitis.

Table 1 shows the predictive values, specificity, and sensitivity of various diagnostic tests. Alvarado score ≥8 provides a 100% positive diagnosis of appendicitis. The combination of an Alvarado score <5 and a CRP level <6 mg/L rules out the diagnosis of AA at 96%. Thus, in our series, the diagnosis of acute appendicitis was missed in only two patients, using the Alvarado score and laboratory data alone. Although positive abdominal CT scan had the highest diagnostic accuracy, we believe that this radiating examination would be unnecessary when dealing with a child with suspected AA and a non-diagnostic ultrasound. Alvarado score and laboratory data would be useful and effective in either affirming or ruling out AA in these patients.

Table 1.

Sensitivity, Specificity, and Predictive Values of Potential Predictors of Acute Appendicitis

	Sensitivity (95% CI)	Specificity (95% CI)	PPVa (95% CI)	NPVa (95% CI)	Accuracya (95% CI)
Alvarado score ≥5	0.85 [0.74–0.93]	0.65 [0.57–0.73]	0.50 [0.44–0.56]	0.92 [0.86–0.95]	0.71 [0.64–0.77]
Alvarado score ≥6	0.63 [0.50–0.75]	0.85 [0.78–0.90]	0.63 [0.53–0.72]	0.85 [0.80–0.89]	0.78 [0.72–0.84]
Alvarado score ≥7	0.40 [0.28–0.53]	0.99 [0.95–0.99]	0.93 [0.75–0.98]	0.78 [0.75–0.81]	0.80 [0.77–0.83]
Alvarado score ≥8	0.18 [0.09–0.29]	1 [0.98–1]	1 [0.71–1]	0.75 [0.73–0.77]	0.76 [0.70–0.82]
Positive CT^b	1 [0.84–1]	0.74 [0.55–0.88]	0.72 [0.59–0.83]	1 [0.85–1]	0.85 [0.72–0.93]
CRP >50 mg/L	0.64 [0.51–0.76]	0.83 [0.77–0.89]	0.61 [0.52–0.70]	0.85 [0.80–0.89]	0.78 [0.72–0.83]
WBC count >15 × 10⁹/L	0.55 [0.42–0.67]	0.80 [0.72–0.86]	0.52 [0.43–0.62]	0.81 [0.76–0.85]	0.72 [0.66–0.78]
Alvarado score ≥5 or CRP ≥6 mg/L	0.97 [0.89–0.99]	0.34 [0.27–0.42]	0.37 [0.35–0.40]	0.96 [0.87–0.99]	0.52 [0.45–0.59]
Alvarado score ≥5 or WBC count ≥10000 ×10⁹/L	0.87 [0.76–0.94]	0.47 [0.38–0.55]	0.40 [0.36–0.44]	0.90 [0.82–94]	0.58 [0.51–0.65]

The best PPV, NPV, and accuracy were bolded.

CT showing enlarged or thickened appendix or secondary signs of appendicitis.

CI, confidence interval; PPV, positive predictive value; NPV, negative predictive value; CT, computed tomography; CRP, C-reactive protein; WBC, white blood cell.

Despite its attractive findings, our study was limited by the retrospective design and the small number of patients. Prospective studies on larger samples are needed to further validate our results.

Footnotes

Authors’ Contributions

M.J. was responsible for conceptualization, project administration, writing (original draft), and writing (review). A.E. and A.B.S. contributed to data curation, conceptualization, and methodology. M.Z. contributed to supervision and validation. M.J. is the guarantor.

Author Disclosure Statement

The authors have no financial or personal relationships with other people or organizations that could potentially and inappropriately influence our work and conclusions.

Funding Information

The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

References

Malia

, Sturm

, Smith

, et al. Predictors for acute appendicitis in children. Pediatr Emerg Care, 2021; 37(12):e962–e968; doi: 10.1097/PEC.0000000000001840

Zouari

, Hbaieb

, Krichen

, et al. Letter to the editor: Correlation between positive ultrasound and acute appendicitis in children with low alvarado score: A prospective cohort study. Surg Infect (Larchmt), 2024; 25(1):83–84; doi: 10.1089/sur.2023.340

Mekitarian Filho

, Horita

, Dos Santos

COG

, et al. Management of acute appendicitis in children in a university hospital. Pediatr Emerg Care, 2023; 39(11):832–835; doi: 10.1097/PEC.0000000000003059

Zouari

, Issaoui

, Hbaieb

, et al. Predictive factors of acute appendicitis in children with non-visualized appendix on ultrasound: A prospective cohort study. Surg Infect (Larchmt), 2024; 25(1):26–31; doi: 10.1089/sur.2023.295.5

Alvarado

. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med, 1986; 15(5):557–564; doi: 10.1016/s0196-0644(86)80993-3