Article, Ultrasound

Predictive value of C-reactive protein, ultrasound and Alvarado score in acute appendicitis: a prospective pediatric cohort

a b s t r a c t

Purpose: To evaluate whether C-reactive protein level and ultrasound (US) results on admission could aid the diagnostic accuracy of Alvarado score.

Methods: A prospective study was performed on children b 14 years admitted for suspected acute appendicitis. Patients were categorized into three groups based on the Alvarado score: group I: score 7-10, group II: score 5-6, group III: score 0-4.

Results: The difference between predictive values of Alvarado score alone and Alvarado score with CRP was not statically significant. The PPV increased from 74.29% (Alvarado score and CRP) to 93.75% (Alvarado score and US) in group 1 (P = .001) and the NPV increased from 64.86 and 79.69% (Alvarado score and CRP) to 82.6 and 88.2% (Alvarado score and US) in group 2 (P = .01) and group 3 (P = .001), respectively.

Conclusions: Alvarado score and ultrasound taken together improve the predictive value of diagnosing acute appendicitis in children.

(C) 2015


Acute pain represents one of the most common cause for children consultation in the emergency department [1]. Clinical diagnosis of appendicitis in children is often challenging even for experienced surgeons. Different disease processes mimic the diagnosis of acute appen- dicitis as there are a number of causes leading to pain in the right iliac fossa particularly in female patients [2,3]. These difficulties likely contrib- ute to the 28% to 57% rates of initially misdiagnosed appendicitis in chil- dren younger than 12 years [4-6]. Recently, different clinical scoring systems aiding in the diagnosis of appendicitis have been developed. Alvarado score is one of the most used scores in children (Table 1) [7]. It provides measurably useful diagnostic information in evaluating children with suspected appendicitis. However, Alvarado score doesn’t provide adequate predictive values to be used in clinical practice as the gold method for determination of the need for surgery [8,9].

The aim of the study was to evaluate whether C-reactive protein (CRP) level and ultrasound (US) results on admission could aid the diag- nostic accuracy of Alvarado score in a prospectively identified cohort of pediatric patients with suspected appendicitis.

? Conflict of Interest: None.

?? Mohamed Zouari, Mohamed Jallouli, Hamdi Louati, Rim Kchaou, Rahma Chtourou,

Ahmed Kotti, Mahdi Ben Dhaou, Hayet Zitouni, and Riadh Mhiri declare that they have no conflict of interest.

? Source of Support: Nil.

* Corresponding author. Tel.: +216 97459586.

E-mail address: [email protected] (M. Zouari).

Materials and methods

A prospective study was performed on children admitted for suspected acute appendicitis at the Paediatric Surgery Unit, Hedi Chaker Hospital, Sfax, Tunisia, between January 2013 and December 2014. The diagnosis of suspected appendicitis was established preoperatively by one of the consultant pediatric surgeons on the basis of clinical history and physical examination. Laboratory tests including white blood cell count and CRP were ordered on admission. C-reactive protein levels were measured by a highly sensitive immunonephelometric method; the upper reference limit for CRP was 6.0 mg/L. Decision for US evalua- tion was left to the discretion of the pediatric surgeon during the initial assessment. Ultrasound was performed by experienced pediatric radiol- ogists during weekdays with all exams interpreted by a radiology resi- dent and attending radiologist. Senior radiology residents performed and interpreted US during night-time hours (7 PM to 8 AM) and week- ends. Ultrasound Radiology reports were classified as positive or nega- tive. A positive report was considered to be a maximum outer diameter of the appendix greater than 6 mm. Negative reports included those in which the appendix measured less than 6 mm and those in which there was no appendix seen on ultrasound with no indirect signs of appendicitis (large amounts of free fluid, phlegmon, or pericecal inflammatory fat changes). The Alvarado score, CRP value, and US result were correlated with the histoPathological findings of the removed ap- pendix. Patients were categorized into three groups based on the Alvarado score (Fig. 1). A score of >= 7 was indicating acute appendicitis, a score of 5 to 6 suggested the need for serial examination and follow-up

0735-6757/(C) 2015

190 M. Zouari et al. / American Journal of Emergency Medicine 34 (2016) 189192

Table 1

The Alvarado scoring system

Mnemonic (MANTRELS) Value

Symptoms Migration 1

Anorexia-acetone 1

Nausea-vomiting 1

Signs Right iliac fossa tenderness 2

Rebound pain 1

Elevation of temperature N 37.3?C 1

Laboratory Leukocytosis 2

Shift to the left 1

Total score 10

and a score below this level meant normal appendix, but the decision to undergo surgery was purely clinical. Patients were operated by conven- tional method of appendectomy in 122 cases and by laparoscopy in 26 cases. Appendicitis was considered present when patients who had un- dergone surgery had a final histology showing acute appendicitis. Pa- tients who did not undergo surgery were considered not to have appendicitis if they did not re-present within 2 weeks from initial dis- charge with acute appendicitis. Negative (NPV) and positive predictive values (PPV) of Alvarado score, CRP and ultrasound were calculated. The differences between groups are presented as 95% confidence inter- vals. P b .05 was considered to indicate statistical significance. All data was analyzed by SPSS version 13.


There were 402 patients admitted for suspected appendicitis from January 2013 to December 2014. One hundred and ten patients were not evaluated with US scans and were excluded from the study. Two hundred ninety-two patients were included in the study after taking in- formed consent. There were 170 (58.2%) males and 122 (41.8%) fe-

males. The mean age was 8.54 +- 3 years, ranging from 3 to 13.8 years. At the time of consultation, the mean duration of pain was 46.8 hours (4-168 hours). Pain was associated with nausea and vomiting in 86 pa- tients. Right iliac fossa tenderness was found in 68 patients.

Among the 292 patients, 144 were treated without surgical ap- proaches and were then discharged from our hospital. None of these

patients has re-presented within 2 weeks from initial discharge with acute appendicitis. The rates of normal appendix, non-Perforated appendicitis, and perforated appendicitis were 6.1%, 73%, and 20.9%. The final diagnoses of patients with normal appendices included colitis, functional gastrointestinal disorders, and mesenteric lymphadenopathy.

The sensitivity, specificity, positive and negative predictive values of Alvarado score, CRP, and US are illustrated in Table 2. The PPV of Alvarado score >= 7 was 71.1% in group I, the NPV of Alvarado score b 7 were 50.78% in group II and 68.9% in group III. The PPV of high CRP, the NPV of normal CRP, the PPV of positive ultrasound scan and the NPV of negative ultrasound result are presented in Table 3. The differ- ence between predictive values of Alvarado score alone and Alvarado score with CRP was not statically significant (P = .453 in group 1, P =

.43 in group 2, P = .08 in group 3). On the contrary, ultrasound was

very helpful to diagnose acute appendicitis: The PPV increased from 74.29% (Alvarado score and CRP) to 93.8% (Alvarado score and ultra- sound) in group 1 (P = .001) and the NPV increased from 64.86 and 79.69% (Alvarado score and CRP) to 82.6 and 88.2% (Alvarado score and ultrasound) in group 2 (P = .01) and group 3 (P = .001), respec- tively (Fig. 2).


Our study showed that CRP level on admission could not aid the diag- nostic accuracy of Alvarado score in acute appendicitis. Despite substantial research, the diagnosis of Pediatric appendicitis remains challenging. Re- cent studies have proposed different Clinical scoring systems aiding in the diagnosis of appendicitis [8]. Ideally, a Clinical score could accurately distinguish those patients that need immediate operative care from those that may benefit from further investigation or observation. Two well-studied appendicitis scores were developed by Alfredo Alvarado and Madan Samuel, with the explicit purpose of diagnosing appendicitis [10]. Several studies validated the Alvarado score as simple, practical and reproducible diagnostic tool for assessing an acute abdomen [11-15]. It has been useful both to reduce the incidence of Negative appendectomy and to avoid delay in therapy [14,16,17]. However, other studies suggest that Alvarado score doesn’t provide adequate predictive values to be used in clinical practice as the sole method for determination of the need

Fig. 1. Management course and outcomes of study cohort.

M. Zouari et al. / American Journal of Emergency Medicine 34 (2016) 189192 191

Table 2

Sensitivity, specificity, and predictive values of AS, CRP, and US



































for surgery [8,9]. The usefulness of inflammatory markers such as white blood cell count, CRP, and other serum markers in the diagnosis of acute appendicitis in children is still controversial. Many conditions can mimic

Table 3

Predictive values of CRP and Ultrasound found for each group

Group PV AS + CRP AS + US AS + CRP + US Group 1 PPV 74.29 93.75 92.31

Group 2 NPV 64.86 82.61 73.42

Group 3 NPV 79.69 88.24 78.35

no appendectomy was performed. Ultrasound radiology reports were classified as negative in cases of lack of visualization of the appendix. This was another limitation of the present study.


C-reactive protein estimation does not improve accuracy in the diag- nosis of acute appendicitis in pediatric patients. However, the Alvarado score and ultrasound taken together improve the predictive value of di- agnosing acute appendicitis in children. We suggest that an Ultrasound imaging should be performed before proceeding to appendectomy es- pecially in patients with moderate or low Alvarado score.

Compliance with ethical requirements

All human and animal studies have been approved by the appropri- ate ethics committee and have therefore been performed in accordance with the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.

Fig. 2. Variation of predictive values for single and combined Diagnostic tests.

acute appendicitis and are associated with an inflammatory response. Al- though inflammatory markers can be helpful in the surgeon making deci- sion, they are poorly reliable in confirming or excluding acute appendicitis [18-33]. Unlike CRP, US was very helpful in the diagnosis of acute appen- dicitis in our study. Because US is a low-cost option, free of ionizing radia- tion, anesthesia, or contrast injection, it has become a widespread initial diagnostic tool in children with suspected appendicitis [34-37]. Ultra- sound improves the diagnostic accuracy of appendicitis with sensitivities and specificities ranging from 71% to 92% and from 96% to 98% [38,39]. Toprak et al [40], in their study, used Alvarado score combined with US find- ings in order to identify patients with a high or low probability of appendicitis. They suggested that imaging (ultrasonography and computed tomography) findings are very useful in the diagnosis of acute appendicitis in children.

Our study was limited by the possibility of discharged patients pre- senting with appendicitis at other hospitals, the relatively small number of patients and the lack of pathological proof in those patients for whom


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