Research Article
Diagnostic Imaging Strategies in Pediatric Appendicitis at Tertiary and Referring Hospitals
Erica I Hodgman1, James H Wood1,2, Lorrie S Burkhalter2, Madhu Subramanian1, Jennifer L
Styers2, Nudrat Khan2 and Robert P Foglia1,2*
1Department of Surgery, Division of Pediatric Surgery, University of Texas Southwestern, Dallas, TX, USA
2Department of Surgery, Division of Pediatric Surgery, Children’s Medical Center Dallas, Dallas, TX, USA
*Corresponding author: Robert P. Foglia, Department of Surgery, Division of Pediatric Surgery, Children’s Medical Center Dallas, 1935 Medical District Blvd Dallas, TX 75235, USA
Published: 11 Aug, 2017
Cite this article as: Hodgman EI, Wood JH, Burkhalter LS,
Subramanian M, Styers JL, Khan N,
et al. Diagnostic Imaging Strategies in
Pediatric Appendicitis at Tertiary and
Referring Hospitals. Clin Surg. 2017;
2: 1588.
Abstract
Background: The diagnosis of pediatric appendicitis has evolved from a clinical evaluation, to one
relying heavily on imaging. Increasing awareness of the danger of ionizing radiation with Computed
Tomography (CT) has led to more frequent use of Ultrasound (US). The study aim was to assess
imaging techniques and their accuracy at Children’s’ Medical Center Dallas (CMC) and its Referring
Hospitals (RH) in patients with a limited differential diagnosis of appendicitis.
Methods: Upon IRB approval, we reviewed the medical records of all boys, who underwent
appendectomy at CMC in one year.
Results: 385 boys, aged 8 to 14 years, underwent appendectomy during the study, 238 (61.8%)
patients initially presented to CMC, 86% had an US, with 80% accuracy, 147 (38.2%) were transferred
from RHs, 96 (65%) patients had a CT before transfer. The ratio of US: CT as the initial imaging
test was 69%:6% at CMC, and at RHs 7%:66% (p < 0.0001), 40 patients were transferred without
an imaging study. After transfer, 22 patients (55%) had an US, 3 (8%) a CT, and 6(16%) had both
US and CT. Only 23 patients underwent appendectomy without imaging. There was no significant
different in rate of appendicitis, perforation, or negative appendectomy between the two groups.
Conclusions: This study shows a great disparity in imaging modalities at different hospitals, and
US has a high accuracy in most patients. US as the initial study, with CT in cases where diagnosis
remains uncertain, both reduces diagnostic uncertainty and radiation risk.
Introduction
The diagnosis of acute appendicitis has evolved from a purely clinical evaluation, based on
history, physical examination, and laboratory findings, to one that relies heavily on imaging,
including Computed Tomography (CT) and Ultrasonography (US). Several studies have
demonstrated a trend toward increased use of CT for the evaluation of pediatric abdominal pain
[1-3]. However, due to radiation exposure and the cost associated with CT, a number of pediatric
institutions have shifted to US as the initial diagnostic imaging modality of choice for appendicitis,
with CT reserved for cases in which US findings are equivocal [4,5]. Other authors have reported
that, for patients between the ages of 1 and 18 years, the use of diagnostic imaging for the diagnosis
pediatric appendicitis depends significantly on the type of hospital in which evaluation takes place
[6].
Even in a highly selected population of children in whom alternative diagnoses are less likely,
very few patients undergo appendectomy at a tertiary children’s medical center without preoperative
imaging. We hypothesized that, because of institutional expertise and around-the-clock
availability of US, the radiographic evaluation of these children is determined by the type of hospital
to which they initially present. The aim of this study was to identify the imaging modalities at a
Children’s Hospital (CH) vs. Referring Hospitals (RH), the ratio of CT:US, and the diagnostic
accuracy of those studies.
Methods
We undertook an IRB approved retrospective review of all boys aged 8-14 years who underwent
appendectomy at Children’s Medical Center Dallas (CMC) between April 2010 and March 2011.
Subjects were identified by query of our operating room database, and data were gathered from
the CMC electronic medical record. We chose to include only boys in this study as, in this limited population, the diagnosis of appendicitis should be fairly straight forward given the lack of potential confounding gynecologic
diagnoses. Patients who had interval appendectomies were excluded
from the study.
Data included information prior to transfer and at CMC,
including use of imaging, which modality, US or CT, and operative
findings and histological findings. A Pediatric Appendicitis Score
(PAS) was calculated for all subjects using laboratory data and findings
as documented in the surgical history and physical examination [7].
Statistically significant differences were evaluated using Student’s
t-test, the Wilcoxon signed rank test, and Fisher’s exact test as
appropriate. All analyses were performed using GraphPad InStat® v.
3.06.
Results
During the study period of one year, 1,005 appendectomies were
performed at our institution, of which 385 met inclusion criteria. 238
(62%) boys initially presented to CMC, and the remaining 147 (38%)
were transferred from RH. There was no difference in the age (11.3 ±
2.0 years vs. 11.2 ± 1.9 years, p = 0.68) or PAS (6 ± 3 vs. 6 ± 2, p = 0.19)
of subjects evaluated initially at CMC versus RH. In the study, 115
children (30%) underwent CT and 198 (51%) had an US as the only
study prior to appendectomy. Forty-six children (12%) had both CT
and US, and 26 (7%) had no imaging in their evaluation.
Initial evaluation
221 children (93%) initally evaluted at CMC had imaging prior
to appendectomy. US was performed in 205 patients (86%), and
had an 80% diagnostic accuracy. The remaining 41 patients with a
non-diagnostic US underwent CT evaluation. CT was used as the
first imaging modality in an additional 16 children (7%). In total, 57
children (24%) had a CT as part of their evaluation if they initially
presented to CMC. 17 (7%) other children had no imaging prior to
appendectomy.
Among the 147 children transferred from an RH, 107 children
(73%) had imaging prior to transfer. 96 (90%) children had a CT, and
11 (10%) had an US study, with no child having both a CT and US
study. Children who presented to a RH were significantly more likely
to have a CT as part of their intitial evaluation than at CMC (65% vs.
24%, RR 2.8, 95% CI 2.4-3.6). Forty children were transferred to CMC
with no imaging performed at the RH. Patients were more likely to
undergo imaging if they initially presented to CMC vs. RH (93% vs.
73%, RR 1.3, 95% CI 1.1-1.4). These data are summarized in Table 1.
Imaging after transfer
Upon arrival, 22 patients (55%) underwent an US, 3 (8%) had a
CT, and 6 (15%) had both US and CT at CMC prior to appendectomy.
Only 9 children (23% of children with no imaging prior to transfer
and 6% of total transferred subjects) were taken to the operating
room without imaging either before or after transfer. Six children
with imaging at a RH, four children with CT and two with US, had
additional imaging at CMC. In all six cases, US was the only additional
imaging used at CMC. In total, 359 (93%) of the 385 boys underwent
an imaging study before appendectomy.
Accuracy of diagnosis
Histological diagnosis was consistent with appendicitis in
381 cases (99%). The rates of perforated appendicits did not differ
between those who presented at CMC versus an RH ( 21% vs. 27%, P
= 0.17). Of the four negative appendectomies (1%), all patients were
initially evaluated at CMC and had imaging prior to appendectomy,
including one patient with an US, one patient with a CT, and two
patients with both US and CT. There were no statistically significant
correlations between incidence of negative appendectomy and either
place of initial presentation or pre-operative imaging modality.
Table 1
Discussion
Acute appendicitis is the most common indication for urgent
operation in children, and this prevalence is reflected in our
experience at CMC, a large metropolitan pediatric tertiary referral
center where 1,005 appendectomies were performed over the
course of the study period. The diagnostic evaluation of pediatric
appendicitis has changed dramatically since the 1990s when US and
CT were first applied as adjuncts to a thorough history and physical
examination. Although physicians increasingly depend on these
imaging modalities, some authors have suggested an experienced
pediatric surgeon should be able to make a diagnosis of appendicitis
without imaging in the majority of cases [2,3,8]. While most clinicians
and families now demand a high degree of diagnostic certainty which
can be achieved only with some form of imaging, we observed that
our institutional practice pattern was vastly different from that of
local facilities that refer patients to us for management. We chose to
study a subset of patients-boys between the ages of 8 and 14 years
for whom the differential diagnosis of right-lower quadrant pain is
narrow. We found that, even in this select group, only a small number
of patients underwent an appendectomy at our institution without
pre-operative imaging. RHs were significantly more likely than CMC
to diagnose appendicitis without imaging, with over one quarter of
transferred patients arriving at CMC without a study. This is likely
for several reasons. There may have been a strong suspicion of the
diagnosis which obviated the need for imaging, and, our Emergency
Department (ED) has advised that the RHs defer imaging prior to
transfer for probable appendicitis.
There was a striking difference in the radiographic strategies
at CMC when compared with RHs. The ratio of US: CT as the first
imaging study was nearly 10:1 at CMC; the exact opposite was true for
patients who underwent imaging at RHs, where 90% of patients had
a CT scan. Similar findings have been reported in recent single- and
multi-institutional reviews. A decade ago, even at children’s hospitals,
CT was used more frequently than US. Bachur reviewed over 50,000
admissions and found that the median use of US for the diagnosis of
appendicitis at 40 participating pediatric hospitals was 6%, whereas
the median utilization of CT was 34% [9].
The addition of CT to the routine evaluation of pediatric
abdominal pain can reduce the misdiagnosis of appendicitis, with
diagnostic sensitivity and specificity of 94% and 95%, respectively [10-
13]. For this reason, some authors have advocated the liberal use of CT
as a means of both reducing the incidence of negative appendectomy and decreasing unneccessary hospitalizations for observation and
serial examination of children with suspected appendicitis [14]. For
children, however, US has distinct advantages including avoidance
of ionizing radiation and reduced cost. In our diagnostic algorithm
US is the imaging study of choice, followed by CT in cases where the
diagnosis remains uncertain. With this approach, we were able to
achieve a negative appendectomy rate of only 1%.
For most clinicians, concerns about the additional cost and
radiation exposure associated with CT outweigh the benefits of
a confirmed diagnosis. Therefore, in pediatric ED, the use of CT
has begun to decline. Over the last five years, our institution has
introduced a diagnostic algorithm beginning with the use the
Pediatric Appendicitis Score (PAS) [4,15]. With this staged approach,
only 20% of patients evaluated by US had equivocal findings that
required CT for confirmation of the diagnosis. The applicability of
US-based protocols for community hospitals has been thought to
be limited by the experience of the radiology staff, and inconsistent
availablility and accuracy of US [16,17]. This is a hurdle which
may not be difficult to resolve. Our study found a high diagnositc
accuracy in the limited number of RH patients who had an US. The
CMC radiologist confirmed the US diagnosis of appendicitis in
nine of these patients. In the other two cases an imaging study was
ordered, and corroborated the RH diagnosis of appendicits. There
is a clear educational opportunity to move to 24 hour 7 day a week
US availability for diagnosis of pediatric appendictis. This study was
limited to boys alone. With broadening the patient population to all
children with right lower quadrant abdominal pain, the differential
diagnosis is larger due to possible gynecologic pathology. This
differential includes ovarian cysts, torsion, and abcess. The US study
has signficant diagnostic accuracy in evaluating this pathology along
with the suspected appendictis. In our limited study population of
boys alone with suspected appendicitis, 93% of patients had some
imaging study. The reasons for the high imaging rate include a study
ordered by the ED staff before a surgeon is even consulted, medical/
legal concerns in regard to an incorrect diangnosis, and the pendulum
has swung to a point that physicians often need to have some imaging
study to corroborate their clinical diagnosis. This study shows that a
liberal US-based imaging strategy minimizes the need for CT scans,
decreasing radiation exposure, and is associated with a very low rate
of negative appendectomy. CT should be reserved for patients where a
diagnosis could not be made by clinical presentation and US findings.
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