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Indian Pediatr 2016;53: 201-202 |
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Clinical Scoring Systems and Radiologic
Imaging in the Diagnosis of Pediatric Appendicitis
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* Rajiv Chadha and Niyaz Ahmed
Khan
From the Department of Pediatric Surgery, Lady
Hardinge Medical College and Kalawati Saran Children’s Hospital, New
Delhi, India.
Email:
[email protected]
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S everal clinical scoring systems have been
developed to improve diagnostic accuracy in cases of suspected acute
appendicitis. In 1986, Alvarado [1] described a scoring system, the
Alvarado or MANTRELS score, to aid the diagnosis of acute appendicits.
Samuel [2] was the first to describe a Pediatric Appendicitis Score
(PAS) specifically for children incorporating eight statistically
significant variables: cough/percussion tenderness/hopping tender-ness
right lower abdomen, anorexia, pyrexia, nausea/emesis, tenderness in
right iliac fossa, leukocytosis, polymorphonuclear leukocytosis, and
migration of pain. Assigning a score of 1 to each parameter apart from
the physical signs which were assigned a score of 2 each, Samuel [2], in
his study of 1170 children, found a sensitivity of 100%, specificity of
92%, positive predictive value (PPV) of 96%, and a negative predictive
value (NPV) of 99%. A PAS score of 6 or greater was indicative of a high
probability of acute appendicits [2].
Several authors have reported that the PAS is a
useful tool to evaluate children with possible acute appendicits [3-5].
According to Bhatt, et al. [3], scores of
£4 help rule out
acute appendicits while scores of £8
help in its prediction. Patients with a PAS of 5-7 may need further
radiologic evaluation [3]. Zuniga, et al. [4] found that with a
PAS cut-off of £3,
there were no patients diagnosed with acute appendicits. If all patients
with PAS of 8 or higher were operated, there was a 5% rate of negative
appendectomy, less than what other studies had shown [4]. Goldman, et
al. [5] also reported that a PAS score of
£7 is valid for the
diagnosis of acute appendicits and a score of
£2 for its exclusion.
However, some authors [6,7] feel that PAS cannot be used as the sole
determinant of the need for surgery in suspected acute appendicits,
primarily because of low predictive values, more so in children <4 years
[7].
The sensitivity and specificity of abdominal computed
tomograms (CT) for investigating acute appendicits in children is
excellent, albeit, with a risk for radiation exposure. This has led the
Canadian Association of Radiologists (CAR) to recommend that, when
abdominal ultrasound (US) is not diagnostic in children with clinical
suspicion for acute appendicits, surgeons should treat without other
imaging [8]. Abdominal ultrasound scoring systems for evaluating
suspected acute appendicits such as the Appy-Score stratification [9]
have also been described. After applying the Appy-Score strata, Fallon,
et al. [9] found that acute appendicits frequency was 0.5% for a
normal completely visualized appendix, 0% for a normal partially
visualized appendix, and that CT imaging after US decreased by 31%.
Significantly, for equivocal US findings, the acute appendicits
frequency was 44%, while for clear evidence of non-perforated or
perforated acute appendicits, the frequency was 92.3% and 100%,
respectively [9]. Ultrasound eliminates radiation but has sensitivity
inferior to CT [10]. Ramarajan, et al. [10] described a staged US
and CT pathway in which US was the initial imaging modality and CT was
recommended only if US was equivocal. The sensitivity, specificity, NPV,
and PPV of the staged US-CT pathway were 99%, 91%, 99%, and 85%,
respectively. Visualization of a normal appendix (negative US) was
sufficient to obviate the need for a CT [10]. This data suggests that by
employing US first in all children who need diagnostic imaging,
radiation exposure may be substantially decreased without decreasing
safety or efficacy. Kosloske, et al. [11] described a similar
protocol based on clinical evaluation with selective use of US and CT
imaging and reported that the sensitivity of this protocol was 99%,
specificity 92%, PPV 95%, and NPV 99%. The accuracy was 97% compared
with an accuracy of 82% for US alone and 90% for CT alone. Kharbanda,
et al. [12] concluded that in children with low but not zero risk
for acute appendicits, to avoid ionizing radiation, an alternative
strategy would be to consider observation or US rather than immediate CT
imaging.
In this issue of Indian Pediatrics, Kim, et
al. [13] describe a retrospective study of 86 patients with
histologically proven acute appendicits in whom both PAS scoring and
abdominal CT scan were performed. Using a cut-off point of 7 or more on
the PAS, the sensitivity was 70.9%, specificity 91.5%, PPV 78.2%, and
NPV 87.9%. CT findings were graded from I to V and a cut-off of Grade
III or higher yielded a sensitivity of 89.5%, specificity of 91.5%, PPV
of 94.8%, and a NPV of 93.7%; both the sensitivity and PPV being
significantly higher than that obtained with a PAS cut-off score of 7 or
more [13]. Significantly, no patient with a PAS of 3 or lower had acute
appendicits. The authors concluded that with PAS scores of 4-6, CT scan
should be performed or else PAS repeated after 4 hours of observation
and hydration. PAS scores of 7 or more need surgical consultation and
abdominal CT [13]. From the findings of this study as well as others
[3-5], it appears safe to conclude that a PAS score of 3 or lower can
rule out acute appendicits. With PAS scores between 4 and 6,
re-evaluation after intravenous fluids and rest can be recommended
[11,12]. If the scores do not improve or if the initial PAS score is 7
or more, US should be the initial imaging test. The finding of a normal
completely or incompletely visualized appendix can rule out acute
appendicits while clear evidence of perforated or non-perforated
appendicitis mandates surgery [9]. If the US findings are equivocal, CT
scan should be performed in view of its higher sensitivity and PPV
[10-12]. Especially in resource-deficient countries like India, this
would appear to be a safe and cost-effective staged diagnostic protocol.
It is also important that ultrasonologists should be well trained to
evaluate suspected acute appendicits, especially in small children, as
improving US accuracy and quality has a big role in reducing CT use
[14].
Funding: None; Competing interest: None
stated.
References
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