Qualitative Research

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Therapeutics and Clinical Risk Management 2017:13 847–854

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Open access Full Text article

http://dx.doi.org/10.2147/TCRM.S134153

Diagnostic reliability of pediatric appendicitis score, ultrasound and low-dose computed tomography scan in children with suspected acute appendicitis

ashraf Othman sayed1

nancy selim Zeidan2

Dalia Monir Fahmy3

hossam a ibrahim4

1Department of Pediatrics, Children and Women’s University hospital, Minia University, el-Minya, egypt; 2Department of Pediatrics, Faculty of Medicine, Cairo University, Cairo, egypt; 3Department of Diagnostic Radiology, Mansoura University hospital, Faculty of Medicine, Mansoura University, Mansoura, egypt; 4Department of surgery, Faculty of Medicine, Cairo University, Cairo, egypt

Background: Diagnosis of appendicitis in children is clinically challenging. Computed tomography (CT) is the gold standard for diagnosis; however, radiation exposure early in life

is a concern with this technique. Therefore, in this study, we aimed to evaluate the diagnostic

reliability of low-dose CT, pediatric appendicitis score (PAS), and abdominal ultrasound (US)

in children with acute appendicitis, to reach a safe diagnosis.

Patients and methods: This retrospective study was conducted on 140 children who were admitted with clinically suspected acute appendicitis (45 with positive appendicitis and

95 children with negative appendicitis). Low-dose CT was performed, and PAS was retro-

spectively calculated for all subjects. US was initially performed for 38 subjects. All results

were compared with the final diagnosis reached by an operative, histopathological analysis

and follow-up.

Results: Low-dose CT showed a sensitivity, specificity, and accuracy of 97.8%, 100%, and 99.3%, respectively. At a cutoff value $5, PAS showed a sensitivity, specificity, and accuracy

of 95%, 84%, and 89%, respectively. Abdominal US examination showed sensitivity, specificity,

and accuracy of 55.6%, 85%, and 71%, respectively. Implementing Poortman’s model resulted

in higher accuracy (92%) of US. There was a significant difference in accuracy between a

low-dose CT and PAS on one side and between Poortman’s model and US examination on the

other side. A diagnostic scheme was suggested using PAS as the excluding tool (PAS #2 send

home and $7 send directly to operation) followed by US examination and reserving low-dose

CT for inconclusive cases. This scheme would eliminate the use of CT for at least 33.7% and

in 7 cases who had initial US examination.

Conclusion: Although CT remains the most accurate and less operator-dependent diagnostic tool for pediatric appendicitis, the radiation hazards could however be minimized using PAS

as an excluding tool and US as the primary imaging modality followed by low-dose CT for

inconclusive cases only.

Keywords: acute appendicitis, children, pediatric appendicitis scoring system, PAS, computed tomography, CT, ultrasound, US

Introduction Acute appendicitis remains the most common acute surgical condition in children

and a major cause of morbidity; appendectomy is still the mainstay of treatment.1

Delayed intervention leads to dramatic complications such as perforation and abscess

formation while rushing to surgery is associated with a high negative appendectomy

Correspondence: Dalia Monir Fahmy Department of Diagnostic Radiology, Faculty of Medicine, Mansoura University hospital, Mansoura University, el-gomhoria street, Mansoura, 35516, egypt Tel +20 109 104 3679 Fax +20 50 229 5025 email daliamonir2525@gmail.com

Journal name: Therapeutics and Clinical Risk Management Article Designation: Original Research Year: 2017 Volume: 13 Running head verso: Sayed et al Running head recto: Reliability of PAS, US, and CT in the diagnosis of pediatric appendicitis DOI: http://dx.doi.org/10.2147/TCRM.S134153

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of up to 15%–30%.2 Diagnosis of appendicitis in children is

challenging, not only because there are so many other non-

surgical conditions that mimic appendicitis,1 but also because

there are difficulties in communication and examination.3

In many hospitals, including ours, pelvic–abdominal

computed tomography (CT) is considered the gold standard

diagnostic tool for the diagnosis of appendicitis in children

owing to its high sensitivity and specificity.4 CT scan has

certainly saved a significant number of patients from under-

going unnecessary surgeries but has also caused unnecessary

radiation exposure in them. Recent studies have reported that

the risk of radiation exposure early in life is up to 25 mSv

per study, which has raised concern regarding the increased

incidence of cancer in pediatric patients.5,6 Another study

predicted that approximately 29,000 future cancer cases will

be linked to CTs performed in the year 2007, with the largest

proportion coming from pelvic–abdominal scans.7 Therefore,

in order to decrease radiation exposure, several protocols of

modified technical parameters (tube voltage, tube current,

and slice thickness) have been implemented.8

Graded compression abdominal ultrasound (US) is a

widespread bedside examination tool which costs less than

CT and poses no radiation hazards but has low sensitivity and

is operator-dependent. Pediatric appendicitis score (PAS) is

a commonly cited appendicitis clinical scoring system that

was developed specifically for children by Samuel.9 To our

knowledge, there are no previously published studies that

investigated PAS performance in comparison to abdominal

US and low-dose CT in our region.

Therefore, we aimed to evaluate the diagnostic reliability

of low-dose CT, PAS, and abdominal US examination in

children with suspected acute appendicitis, in order to reach

a safe diagnosis with less radiation hazard.

Subjects and methods Design and study population This is a retrospective cross-sectional study conducted over

18 months from March 2015 to September 2016 at a major

urban institution. Ethical approval from the Ethic Committee

of Dar Al-Shifa Hospital was obtained for this study. The

committee waived the need for an informed patient consent

(from parent or guardian) owing to the retrospective nature

of the research and as it did not seem to jeopardize patient

confidentiality, privacy, or safety.

inclusion criteria All children of both sexes between the age of 4 and 18 years

who were admitted with clinically suspected acute appendi-

citis were included in this study.

exclusion criteria Children aged below 4 or above 18 years at the time of

operation, or with incomplete medical records, or those

who underwent appendectomy incidentally, or with chronic

abdominal pain were excluded from this study.

Result comparison with final diagnosis The PAS and imaging (CT and US) results were compared

with the final diagnosis reached by surgery and histopatho-

logical analysis or by follow up.

Clinical and laboratory assessment The following data were collected from the automated and

nonautomated medical records in the hospital: age, gender,

duration of abdominal symptoms (days), and weight (kg).

PAS values were calculated retrospectively for each

patient according to the original PAS definition.9 The

8 components of PAS are as follows: fever, anorexia, nausea/

vomiting, migration of the pain to the right lower quadrant

(RLQ), tenderness on light palpation of RLQ, cough/

percussion/heel tapping tenderness at the RLQ, leukocytosis,

and polymorphonuclear neutrophilia; all components of

PAS were scored 1 point, except, right quadrant tenderness

and cough/percussion/heel tapping tenderness were scored

2 points (Table 1). Clinical assessment was performed by

licensed pediatricians in the emergency room upon the initial

admission of the patients.

Radiological imaging Computed tomography All subjects (n=140) included in this study had CT examina- tion of the abdomen and pelvis, which was performed after

fasting for at least 4 hours prior to scanning. Our protocol

included intake of 1,000 mL of oral contrast solution (non-

ionic) over a period of 90 min, followed by pre- and post-

contrast phase (venous). However, in certain circumstances,

such as severe vomiting or urgent cases that were planned for

Table 1 Components of pediatric appendicitis score

Signs/symptoms Point value

nausea/emesis 1 anorexia 1 Migration of pain to RlQ 1 low-grade fever ($38.0°C) 1 RlQ tenderness on light palpation 2 Cough/percussion/heel tapping tenderness at RlQ 2 leukocytosis (.10,000/mm3) 1 left shift (.75% neutrophilia) 1 Total 10

Abbreviation: RlQ, right lower quadrant.

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Reliability of Pas, Us, and CT in the diagnosis of pediatric appendicitis

operation soon after CT scan, oral intakes of contrast were

eliminated from our protocol.

CT scan was performed using a Siemens SOMATOM

defined Flash dual source 128 multi-detector scanner

(Siemens Medical Solutions, Forchheim, Germany): tube

voltage, 100 kVp; tube current, 87/190 MA; slice thick-

ness, 6 mm; and 40 mL Xenetix® (Guerbet, Gorinchem, the

Netherlands) at 4 m/s. Postcontrast scan was performed 60 s

after intravenous injection of Xenetix 350. The low-dose

technique was implemented and a size-specific dose estimate

(SSDE), an approximation of absorbed dose incorporating

patient diameter, and effective dose (ED) was calculated

for each scan.

image analysis CT images were reviewed by a senior radiologist (DF) with

15 years’ experience in abdominal imaging, who was blinded

to the clinical findings and laboratory results. The criteria

for diagnosis of acute appendicitis included the following:

swollen appendix (outer diameter exceeding 6 mm) with

or without fecolith, enhanced walls, and peri-appendiceal

strands. The signs of perforation included the following: free

intra-peritoneal air and excess peri-appendiceal, pelvic, or

abdominal fluid. CT findings were interpreted as negative if

an appendix was not visualized, had an outer diameter of less

than 6 mm, and had absence of peri-appendiceal strands.

Ultrasound examination All US examinations were performed using a curved

3.5–5.0 MHz array and a linear 6 MHz array (ultrasound

machine GE volusone E8 and E10). The criteria for diagno-

sis of acute appendicitis were as follows: local transducer

tenderness, noncompressible appendix, a thickened appendix

(diameter greater than 6 mm), presence of an appendicoliths,

peri-appendiceal fat infiltration, and free fluid adjacent to

the appendix. In addition to a routine abdominal and pelvic

US, all ultrasound examinations were performed in our

institution by licensed general radiologists with at least

5 years’ experience.

Operative and histopathological analysis Surgery was performed by a consultant general surgeon with

more than 20 years’ of experience. The existence of polymor-

phonuclear leukocytes, lymphocytes, or plasma cells in appen-

diceal biopsy was considered positive for appendicitis.

Negative appendectomy was defined as, 1) an operation

with a preoperative diagnosis of appendicitis, and 2) absence

or minimal acute inflammatory cells in the case of appendec-

tomy, or normal appearance of the appendix.

Follow-up Patients who had a stable clinical condition and with a nega-

tive CT scan for appendicitis were sent home and received a

follow-up phone call after 1 week to assess their condition

and cessation of symptoms. Patients, who had other diseases

that caused acute abdominal pain other than appendicitis,

discovered by imaging and laboratory tests, were treated

according to their condition, as usual.

statistical analysis IBM SPSS software package (Statistical Package for Social

Sciences, version 20 for Windows) was used to analyze data.

A 1-sample Kolmogorov–Smirnov test was used to assess

whether the data were normally distributed. Continuous

variables were presented as mean ± standard deviation and data were compared using an unpaired t-test. Categorical

variables were expressed as numbers and percentages and

analyzed for comparisons using chi-square test.

For evaluating the predictive value of PAS in the diagno-

sis of acute appendicitis, the sensitivity, specificity, positive

predictive value (PPV), negative predictive value (NPV), and

accuracy were calculated. In addition, receiver operating char-

acteristic (ROC) curves were analyzed for the overall PAS

performance. At the 5% level of significance, P-value less

than 0.05 was considered significant in all statistical tests.

Results A total of 140 patients were included in this study; 45 patients

(positive appendicitis group) had surgery followed by

histopathological analysis that confirmed acute appendi-

citis. None had a negative appendectomy. The remaining

95 patients (negative appendicitis group) had diseases other

than appendicitis that were revealed by CT scan and clinical

follow-up; none of these patients showed any complications

related to a missed diagnosis of appendicitis (Table 2).

Table 2 The final diagnosis in the negative appendicitis group (n=95)

Diagnosis Number of cases

Mesenteric lymphadenitis 42 Ovarian cyst 18 Colitis 25 enteritis 4 Crohn’s 1 intestinal obstruction 1 Diverticulitis 1 acute paniculitis 1 gastritis 1 Ureteric stone 1 Total 95

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Out of 140 patients included in this study, 77 were

males and 63 were females. No significant difference was

found between the positive and negative appendicitis groups

regarding patients’ gender or weight. Patients’ ages ranged

from 4 to 16 years and their mean age was (11±0.67 years). Table 3 summarizes the demographic data.

All patients (n=140) included in this study underwent CT scan; it was the initial imaging in 102 patients and

subsequently US imaging was performed for the remaining

38 patients. Forty-four patients had radiological findings

coping with acute appendicitis in CT examination, which

was correlated with the histopathological findings: 16 showed

dense fecolith; perforation was noted in 7 (3 of them were

associated with fecolith as shown in Figure 1); and 1 was

associated with an acute abscess. The most common loca-

tion of the appendix with inflammation was pelvic region

(19 cases, 42%) followed by retrocecal (16 cases, 36%).

Table 4 summarizes radiological signs of patients.

Only 1 patient was misdiagnosed by CT as having a

normal appendix with a probably complicated right ovarian

cyst. As this patient had persistent pain and tenderness in

right iliac fossa, she was referred to laparoscopic surgery

that revealed mild inflammation in her appendix with right

corpus luteum cyst.

CT examination showed a sensitivity of 97.8% (95%

confidence interval [CI] =88.2%–99.9%), specificity of 100% (95% CI =96.2%–100%), PPV of 100%, NPV of 98.7% (95% CI =93.2%–99.9%), and an accuracy of 99.3%.

Table 3 Demographic and clinical characteristics of all study patients (n=140)a

Appendicitis (n=45)

No appendicitis (n=95)

P-value

age (years) 13.1±4 13.2±3.9 P=0.885b

t-value =−0.144 gender

Male Female

27 (60%) 18 (40%)

50 (54%) 45 (46%)

χ2=0.6699 P=0.413c

Weight (kg) 45.65±18.2 47.2±19 t-value =0.586 P=0.559b

symptoms duration (days)

1.85±0.56 2.0±1.11 P=0.210b

t-value =1.258 Pediatric appendicitis score

5.34±1.15 2.48±1.11 t-value =−17.947 P,0.001b

Notes: aContinuous variables are presented as mean ± standard deviation; categorical variables as numbers with percentages; bUnpaired t-test, cchi-square test.

Figure 1 Preoperative postcontrast abdominal–pelvic CT scan of a child aged 14 years, who presented with abdominal pain and vomiting (Pas score =5). Notes: (A and B) Coronal reformatted images showed distended appendix with thick edematous walls, diameter 15 mm (long black arrow in A), which contains fecolith (short double black arrows in A). a tiny focus of air near its tip denoting contained perforation (white arrow in B); multiple associated regional and mesenteric lymph nodes (black arrows in B). (C) axial image showed distended appendix with thick edematous walls surrounded by peri-appendiceal fat stranding, and mild peri-appendiceal fluid (black arrow in C). Abbreviations: Pas, pediatric appendicitis score; CT, computed tomography.

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Reliability of Pas, Us, and CT in the diagnosis of pediatric appendicitis

The mean dose-length product was 150 mGy/cm (ranging

from 115 to 200 mGy/cm) and mean effective dose of radia-

tion was 3.1 mSv (ranging from 2.2 to 3.4 mSv).

The abdominal US examination was the initial imaging

in 38 patients; it gave true positive results in 10 cases

(26.3%), true negative in 17 cases (44.7%), false negative

(missed appendicitis) in 8 cases (21%), and false positive

(negative appendectomy) in 3 cases (7.9%). It showed a

sensitivity of 55.6% (95% CI =30.8%–78.5%), specificity of 85% (95% CI =62.1%–96.8%), PPV of 76.9% (95% CI =52%–91%), NPV of 68% (95% CI =55.1%–78.6%), and an accuracy of 71%. In 2 patients (who were negative

for appendicitis), abdominal US examination revealed right

ovarian cysts 3 cm and 3.5 cm in diameter, respectively.

Following Poortman’s model10 (which consisted of

combination of US as the primary examination followed by

CT in nondiagnostic US examination) yielded a sensitivity

of 100% (95% CI =81.5%–100%), specificity of 85% (95% CI =62.1%–94.5%), PPV of 85.7% (95% CI =67.9%–78.6%), an accuracy of 92%, negative appendectomy rate of 7.9%,

and no missed positive appendicitis cases. It alone would

have avoided the use of CT in 13/38 cases.

There was a significant difference between the PAS

in positive and negative appendicitis groups (P,0.001).

In this study, PAS score $5 was found to be the best cutoff

point compatible with acute appendicitis; it resulted in a

sensitivity of 95% (95% CI =29%–98%), specificity of 84% (95% CI =76%–90%), PPV of 82% (95% CI =73%–89%), NPV of 82% (95% CI =73%–89%), and accuracy of 89% (as shown in Figure 2). Further analysis of PAS showed

that it is more useful as an exclusive tool; PAS $2 showed

the highest sensitivity of 97.8% (95% CI =88.2%–99.9%) with only a single false negative case (missed appendicitis),

whereas using higher cutoff value (PAS $7) showed the

highest specificity 97.9% (95% CI =2.6%–99.7%) with only 2 cases of negative appendectomy (Table 5).

On comparing low-dose CT, US, Poortman’s model, and

PAS (using a cutoff value $5), low-dose CT showed the high-

est accuracy, whereas US showed the lowest (Table 6).

On one side, there was a significant difference in accuracy

between low-dose CT scans and PAS (P,0.001), and on the

other side, there was a significant difference between Poort-

man’s model and US (P,0.02).

Finally, we propose a diagnostic scheme that depends on

the clinical score (PAS) as an initial diagnostic tool followed

by US examination (if PAS is in the range of 3–6), preserving

low-dose CT as the last step for cases with inconclusive US

findings (as shown in Figure 3). Following this scheme would

have eliminated the use of CT for at least 47/140 (33.6%)

patients who had PAS #2 or $7. Unfortunately, not all

patients included in this study had US examination; however,

following this scheme for the remaining 38 patients who had

initial US examination would have avoided the use of CT in

7 cases (PAS 3–6 and positive US findings).

Discussion Owing to its high diagnostic accuracy, CT is utilized widely

in the management of appendicitis, but this trend is accom-

panied by an increased radiation exposure and long-term

Table 4 Computed tomography (CT) findings in positive appendicitis cases

CT findings Patients (n)

edematous wall 44 Perforation 8 Fecolith 16 Fecolith associated with perforation 3 enlarged regional and mesenteric lymph nodes 24 abscess 1 according to the appendix location

Pelvic Retrocecal subhepatic anterior

19 16 2 7

Figure 2 Receiver operating characteristic curve for the performance of pediatric appendicitis score. Note: Area under curve (95% confidence interval) =0.951 (0.923–0.979).

Table 5 Sensitivity and specificity of PAS values (using 3 different cutoff points) in all subjects (n=140), according to final diagnosis

PAS cutoff Sensitivity Specificity Accuracy

Pas $2 97.8% (95% Ci: 88.2–99.9)

26.3% (95% Ci: 17.8–36.4)

49.3%

Pas $5 95% (95% Ci: 29–98)

84% (95% Ci: 76–90)

89%

Pas $7 42.2% (95% Ci: 27.7–57.9)

97.9% (95% Ci: 92.6–99.7)

73%

Abbreviations: PAS, pediatric appendicitis score; CI, confidence interval.

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cancer risks.4 Two main pathways have been suggested

to decrease these hazards and maintain high diagnostic

accuracy; first to decrease the radiation dose by implement-

ing a low-dose protocol in pediatric CT (image gently), and

second, to decrease the utilization of CT by using a clinical

score and US examination either alone or prior to CT, which

can be performed in case of doubt (this decision should be

made wisely).

In the current study, a low-dose protocol was used for all

patients with a mean radiation dose of 3.1 mSv. Although

the low-dose technique resulted in reduced quality of images

it did not affect the diagnostic accuracy. CT examination

showed a sensitivity of 97.8%, specificity of 100%, and an

accuracy of 99.3%. These results agree with other studies11–14

in which the authors have reported no significant difference

in sensitivity, specificity, negative appendectomy, or missed

appendicitis rate between low-dose protocol and regular

CT scan.

In the current study, graded compression US was per-

formed for a relatively small group of patients (38 cases). It

had less sensitivity (55.6%), specificity (85%), and accuracy

(71%) compared to CT, which could be attributed to 2 main

reasons. First, all sonographic examinations were performed

in our institution by a general radiologist, not by a pediatric

sonologist; second, owing to the high percentage of a retro-

cecal position of the appendix (36%) which hindered its

detection by the US.

Poortman et al10 suggested a diagnostic model for appen-

dicitis that included graded compression US as the initial

imaging modality followed by CT only in nondiagnostic US

examination. Applying this model to a relatively small group

of patients in the current study, it was found that primary US

examination dramatically improved the sensitivity (100%),

specificity (85%), and accuracy (92%), and yielded a nega-

tive appendectomy rate of 8% and no missed appendicitis.

These results are similar to those in the studies of Poortman

et al10 (sensitivity of 100%, specificity of 86%, and negative

appendectomy 8%), Ramarajan et al15 (sensitivity of 99%,

specificity of 91%, and negative appendectomy 7%), and

Thirumoorthi et al16 (sensitivity of 94.2%, specificity of

97.5%, negative appendectomy 1.8%, and missed appen-

dicitis 0%).

One study reported an increasing trend of using US as

the first imaging tool (about 69% instead of 32.6%) during

the period from 2008 through 2013, whereas the use of CT

was decreased.18 In the current study, US examination was

the initial imaging modality in 27% of the cases suspected

to have appendicitis. In contradiction to other studies which

reported utilization of preoperative CT in about 40% of the

cases,17–19 in our study, all patients undergoing appendectomy

had received a preoperative CT, even if the patient had a US

diagnosis of appendicitis. The reasons behind this could be

that surgeons in our region have less trust in US results as

compared to CT, which has higher sensitivity, specificity,

and is indeed less operator-dependent. Although CT is more

Table 6 Comparison of performance between CT, Us, Poortman’s model, and Pas

PAS $5 (n=140)

CT (n=140)

US (n=38)

Poortman’s model (n=38)

sensitivity 95% 97.8% 55.6% 100% Specificity 84% 100% 85% 85% Positive predictive value 82% 100% 76.9% 85.7% negative predictive value 82% 98.7% 68% 100% accuracy 89% 99.3% 71% 92% negative appendectomy (false positive)

4 (2.8%) 0 3 (7.9%) 3 (7.9%)

Missed appendicitis (false negative)

9 (6.4%) 1 (0.7%) 8 (21%) 0

Abbreviations: CT, computed tomography; Pas, pediatric appendicitis score; Us, ultrasound.

Figure 3 a suggested scheme for the diagnosis of appendicitis using Pas, Us, and low-dose CT scan. Abbreviations: Pas, pediatric appendicitis score; Us, ultrasound; CT, computed tomography; −ve, negative; +ve, positive.

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Reliability of Pas, Us, and CT in the diagnosis of pediatric appendicitis

expensive than US, it is still less expensive than the cost of

negative appendectomy or managing complications such as

a perforated appendix. Furthermore, physicians find difficulty

in convincing some parents of the diagnosis of acute appen-

dicitis based only on clinical and US findings; they believe

that CT scan can be less harmful than doing unnecessary

appendectomy with possible surgical complications.

The main drawback of US is that it is highly operator-

dependent and its accuracy is affected dramatically by the

examiner’s own experience. That is why CT scan utilization

is higher in general hospitals (including our hospital) when

compared to specialized pediatric hospitals. This is in agree-

ment with Kotagal et al17 who noted 8 times higher use of

CT in nonpediatric hospitals.

Appendicitis scoring systems have been developed as a

diagnostic tool to improve the decision-making process in

patients with suspected acute appendicitis.20 In the current

study, PAS score $5 was found to be the best cutoff point

compatible with acute appendicitis, with a sensitivity of 95%,

specificity of 84%, and an accuracy of 89%. However, there

was still a significant difference in accuracy between low-

dose CT and PAS. In this study, it has been found that rely-

ing on a single PAS cutoff value would result in a negative

appendectomy in 4 cases (2.8%) and missed appendicitis in

9 cases (6.4%). Other studies suggested a modified pathway

utilizing both PAS and imaging; Lourenco et al21 suggested

that patients with a PAS of 1 to 3 could be discharged without

further imaging examination, patients who had a PAS of 4

to 6 would require further imaging examination, and those

who had a PAS of 7 to 10 required surgical consultation

without imaging examination. Similarly, Goldman et al22

reported that a score of 7 or greater is valid for the diagnosis

of appendicitis and a score of 2 or under is valid for the exclu-

sion of appendicitis; and Zúñiga et al23 found that at PAS

of #3 no patients were diagnosed with acute appendicitis,

and if all patients with PAS of 8 or higher were operated on,

there was a 5% rate of negative appendectomy.

Similarly, in the current study, we found that using

PAS #2 to exclude the diagnosis of appendicitis would have

led to missing only 1 case (0.7%), whereas using PAS $7 as

an indication for surgery would have led to negative appen-

dectomy in 2 cases (1.4%); the rest of the patients having

PAS between 3 and 6 were in need of further imaging studies.

Accordingly, we have proposed a diagnostic scheme for acute

appendicitis (Figure 3) that combines three diagnostic tools

(PAS, US, and low-dose CT). Obviously, following this

pathway will result in fewer cases of missed appendicitis or

negative appendectomy as compared to using US or PAS

alone, whilst also lowering CT utilization. We found that fol-

lowing this scheme would have eliminated the use of CT for

at least 33.6% (47/140) of the patients who had PAS #2 or

$7, and in 7 patients who had initial US examination before

CT. In contrast, these results disagree with Srinivasan et al24

who found little benefit in performing CT for patients with

PAS ,6 and negative US findings. Again, this could be

attributed to the fact that our study was conducted in a general

hospital and not in a tertiary pediatric center, and because

US was performed by general radiologists and not pediatric

sonologists. However, Rezak et al25 reported about 27% theo-

retical decrease in CT utilization in children with suspected

appendicitis with modified Alvarado score (5–7).

In the current study, PAS that equals 5 or more was found

to be the best cutoff value for diagnosis of appendicitis;

however, this value is less than that found by several other

studies including Samuel9 who created this score system

back in 2002. This difference could be attributed to inher-

ited difference between prospective and retrospective study.

In the current study, examination of patients was performed

by pediatricians and not by pediatric surgeons who could

have underestimated the clinical signs. Other factors related

to local population habits, such as giving children several

analgesics and antipyretics without medical prescription,

which could mask clinical signs. Another factor is difficulty

in communication, as our hospital serves patients coming

from multiple nationalities with different languages. To our

knowledge, this is the first study to assess the validity of PAS

as a diagnostic tool for pediatric appendicitis in our region;

further large prospective multicenter study is recommended

to clarify more its diagnostic value.

There are some limitations in this study. First, the overall

low number of cases included and the even fewer cases that

had US examinations. As the number of patients who had

US examination was less than those who had CT examina-

tion, we were not able to apply Poortman’s model and our

final diagnostic scheme for all cases. Second, all cases had

low-dose CT examination performed, and we were not able

to compare between low and ordinary dose CT in order to

get true measurements of degree of dose reduction. Finally,

the retrospective nature of this study hindered our ability to

assess the feasibility of the suggested diagnostic scheme on

daily work instead of assumption.

Conclusion Although CT remains the most accurate and less operator-

dependent diagnostic tool for pediatric appendicitis, radiation

hazards could be minimized using PAS as an excluding tool

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and US as primary imaging modality, followed by low-dose

CT for inconclusive cases only.

Disclosure The authors report no conflicts of interest in this work.

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