ASSOCIATION FOR ACADEMIC SURGERY
The Lack of Efficacy for Oral Contrast in the Diagnosis of Appendicitis by
Carrie A. Laituri, M.D., Jason D. Fraser, M.D., Pablo Aguayo, M.D., Frankie B. Fike, M.D.,
Carissa L. Garey, M.D., Susan W. Sharp, Ph.D., Daniel J. Ostlie, M.D., and Shawn D. St. Peter, M.D.1
Department of Surgery, Children’s Mercy Hospital, Kansas City, Missouri
Submitted for publication December 21, 2010
Background. Oral contrast is often used with com-
puted tomography (CT) for the diagnosis of appendici-
tis. This adjunct adds time to evaluation, not all
patients can tolerate enteric bolus, and the diagnostic
advantages have not been well defined. Therefore, we
reviewed our experience to evaluate the impact of
oral contrast on diagnostic efficiency and its impact
on the patient.
Methods. After obtaining IRB approval, a retrospec-
tive review was conducted on patients who underwent
CT with oral contrast for the indication of appendicitis
over the last 4 years. Data recorded included demo-
graphics, CT results, emergency room course, opera-
images were reviewed to identify presence/absence of
contrast at or beyond the terminal ileum.
Results. There were 1561 patients, of whom, 652
(41.8%) were diagnosed with appendicitis and 909
(58.2%) were not (non-appendicitis). Contrast was
identified at least to the level of the terminal ileum in
72.4% of the entire population. The contrast was pres-
ent in 76.2% of the non-appendicitis patients and
67.0% of the appendicitis patients (P [ 0.01). Mean
imaging was 105.5 min, which was longer in patients
with appendicitis (112.2 min) compared with non-
appendicitis patients (100.9 min) (P [ 0.01). Emesis of
the contrast occurred in 19.3% of those with appendici-
tis and 12.9% of those without appendicitis (P [ 0.001).
Nasogastric tubes were placed in 5.8% of those with ap-
pendicitis and 5.1% of those without (P [ 0.37). Appen-
dicitis was confirmed at operation in 94.3% of those
with contrast in the area and 94.4% of those without
(P [ 1.0). Pathology confirmed appendicitis in 90.6%
of those with contrast in the area and 94.0% of those
without (P [ 0.17).
Conclusion. Nearly 30% of patients receiving oral
contrast for the CT diagnosis of appendicitis do not
have contrast in the point of interest at the expense
of emesis, nasogastric tube placement, and diagnostic
delay. These detriments are amplified in patients who
have appendicitis. Further, there appears to be no di-
agnostic compromise in those without contrast in the
? 2011 Elsevier Inc. All rights reserved.
Key Words: appendicitis; oral contrast; computed
Computed tomography (CT) is frequently utilized in
the diagnosis of appendicitis. Many protocols employ
enteric contrast in attempt to enhance diagnostic accu-
racy. Patients with abdominal complaints, however, do
not readily accept or retain the contrast bolus at the ex-
pense of additional time added to their evaluation.
Therefore, we reviewed our experience to evaluate the
impact of oral contrast on diagnostic efficiency and its
impact on the patient.
After obtaining IRB approval, a retrospective review was conducted
on all patients who underwent CT with oral contrast for the indication
formed to rule out appendicitis in our center routinely receive intrave-
nous contrast for the detection of inflammatory changes. Data
recorded included demographics, CT results, emergency room course,
operative findings, and pathology interpretation. Admission data re-
corded included age, weight, body mass index, white blood cell (WBC)
count, and maximum temperature. All CT scans were interpreted by
1To whom correspondence and reprint requests should be ad-
dressed at Department of Pediatric Surgery, Children’s Mercy Hospi-
tal and Clinics,2401 Gillham Road, Kansas City, MO 64108. E-mail:
? 2011 Elsevier Inc. All rights reserved.
Journal of Surgical Research 170, 100–103 (2011)
to identify presence or absence of contrast at or beyond the terminal il-
tion found in the operative report and pathology report.
Patients clinically diagnosed with appendicitis and treated as such
were compared with those who were not treated for appendicitis, us-
egorical variables. Diagnostic parameters were compared between
those with contrast in the terminal ileum and those without.
During the study period, there were a total of 1561
patients who underwent computed tomography with
oral contrast in the evaluation for possible appendicitis,
of whom 652 (41.8%) were diagnosed with appendicitis
and 909 (58.2%) had another diagnosis (non-appendici-
tis). There were 811 females and 750 males. Patient
characteristics between those with appendicitis and
those without are listed in Table 1.
All patients were administered contrast consisting of
a mean contrast volume/dose of 318.8 6 112.3 mL with
an average of two doses of contrast being administered
(mean total volume of contrast of 616.9 6 243.4 mL).
Contrast was identified in the terminal ileum in
72.4% of the entire population. The mean total time
spent in the emergency department was 7.0 6 2.1 h.
Hospital course and outcomes are shown in Table 2.
Those with appendicitis suffered more emesis, longer
time to scan, and fewer patients had contrast in the ter-
There were five patients (0.55%) who were initially
not diagnosed with appendicitis who underwent an
operation. One patient was found to have Wilm’s tu-
mor and underwent resection for this lesion. One pa-
tient was admitted for observation and pain control
and underwent an appendectomy the following day
for unrelenting symptoms. The remaining three pa-
tients were discharged and later returned with per-
sistent pain, and appendectomy was performed upon
In the patients with no contrast in the area of inter-
est, there was no difference in positive surgical findings
of appendicitis, pathologic findings of appendicitis, or
CT results corresponding with operative findings. The
diagnostic parameters relative to clinical findings be-
tween those with contrast in the ileum compared with
those without are listed in Table 3.
Thereislittle debatethat CTisasensitiveand specif-
ic imaging study in the workup of appendicitis [1–11].
Its use has significantly reduced the negative appen-
dectomy rate , which has traditionally been accepted
in up to 20% . There are currently a variety of CT
protocols for the diagnosis of appendicitis, varying by
institution parameters, including oral or intravenous
contrast, rectal contrast, noncontrast scans, and
Patient Characteristics Between Patients Treated for Appendicitis (Appendicitis) After the CT Scan and Those
Who Were Not (Non-Appendicitis)
Appendicitis (652) Non-appendicitis (909)
Body mass index (kg/m2)
10.0 6 4.1
369 Males (56.6%)
40.5 6 20.6
19.9 6 7.1
15.7 6 5.9
37.7 6 1.1
10.4 6 6.4
381 Males (41.9%)
40.6 6 22.2
19.8 6 6.7
11.0 6 5.6
37.3 6 1.1
Outcomes Between Patients Treated for Appendicitis (Appendicitis) After the CT Scan and Those Who Were Not
Appendicitis (652)Non-appendicitis (909)
ER time (h)
Total contrast (mL)
Scan time (min)
Contrast in terminal ileum
7.0 6 2.0
322.2 6 104.1
2.0 6 0.4
631.3 6 234.6
112.2 6 108.6
7.1 6 2.2
316.5 6 117.4
1.9 6 0.3
607.4 6 248.6
100.2 6 45.6
LAITURI ET AL.: ORAL CONTRAST FOR COMPUTED TOMOGRAPHY
focused appendiceal imaging versus scanning through
the entire abdomen and pelvis.
Noncontrast CT scans have reported sensitivities of
93% and specificity of 96% in adult populations in diag-
nosing appendicitis [5, 8, 9]. Others have reported that
the diagnostic performance of CT without oral contrast
was similar or better than with oral contrast (sensitiv-
ity, 95% versus 92% and specificity, 97 versus 94%)
. Accuracy rates of noncontrast CT scans have
been reported to range from 93% to 97% [14–16].
Some question the value of oral contrast due to the
helical scanning and multidetector CT . Earlier-
generation CT scans may have mandated contrast sup-
plementation due to longer image acquisition time.
Also, artifact caused by respiratory and peristaltic mo-
tion likely led to image degradation. However, helical
scanning and multidetector CT with rapid image acqui-
sition times have made the use of oral contrast of
questionable value . Several factors improve non-
contrast CT interpretation accuracy, including pres-
ence of intra-abdominal fat, increased severity of
disease at image acquisition, thin sections, coronal
and sagittal reformatting, and the experience of the in-
terpreting radiologist . Since most children tend to
have limited amount of intra-abdominal fat, some be-
lieve that this limits the usefulness of nonenhanced
CT scans ,while others believe thatthe accuracyre-
mains unchanged with varying body mass indexes .
Onestudythatdirectly addressedthisissuedid notfind
a significant difference in CT accuracy with varying
body mass index . Six of the seven studies in this
systematic review included radiologists as investiga-
tors and all support the use of noncontrast CT scans
for the diagnosis of appendicitis [18–23]. The diagnostic
advantages of oral contrast have not been well defined.
In our series, over 30% of patients receiving oral con-
trast for the CT diagnosis of appendicitis do not have
contrast in the point of interest. It becomes difficult to
justify the use of an adjunct that has no effect in one-
third of the patients, particularly when it is at the
expense of emesis, nasogastric tube placement, and di-
agnostic delay. These detriments are amplified in pa-
tients who have appendicitis. Given the burden of
contrast placement, this study would have to document
substantial diagnostic benefit, not simply show equiva-
lence, in order to justify the routine of contrast. How-
ever, there was no diagnostic compromise in those
without contrast in the terminal ileum as they showed
a decreased percentage of equivocal reads, and there
was no difference in negative appendectomy rates. It
is possible that more of the patients without contrast
trast, which may slightly boost the diagnostic accuracy
in the noncontrast group. Regardless, given the fact
that we did not document a glaring diagnostic advan-
tage to having contrast in the terminal ileum, it would
appear prudent to recommend CT without oral contrast
when this modality is used. While we do not have a true
control group of patients with no oral contrast ordered,
we used time to scan as a surrogate since this interval
was occupied by the delivery of oral contrast. We antic-
ipate that it would still take a little time to get the scan
without oral contrast, with a wait time averaging 2 h; it
is reasonable to assume no contrast would result in
a scan obtained more than 1 h earlier, in addition to re-
ducing emesis and nasogastric intubation. We have be-
gun to attain limited CT scans without oral contrast,
and future data will help delineate this issue.
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Diagnostic Parameters Based on Clinical Outcome Between Those With Contrast in the Terminal and Those
Contrast in terminal ileum (1130) No contrast in ileum (431)
Findings of appendicitis in OR
Pathologic evidence of appendicitis
CT diagnosis concordant with OR findings
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LAITURI ET AL.: ORAL CONTRAST FOR COMPUTED TOMOGRAPHY