Indication and usefulness of ultrasonography for suspected acute appendicitis at the emergency department

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Indication and usefulness of ultrasonography for suspected
acute appendicitis at the emergency department


1Radiodiagnosis Department. 2Emergency Department. Río Hortera University Hospital. Valladolid, Spain.
Background: Appendicitis is the most common cause of acute abdominal pain and
Susana Sánchez Ramón
subsequent surgery. For that reason the diagnosis of this condition is a cause of big
C/ Ciudad de la Habana 19, 2ºA
concern in emergency departments.
47016 Valladolid
Objective: The aim of the present study was to assess the usefulness of ultrasono-
E-mail: [email protected]
graphy in the diagnosis of acute appendicitis.
Methods: Retrospective study which included patients presented in the emergency de-
partment with abdominal pain of suspected acute abdominal disorder origin and re-
mitted to undergone ultrasonography to rule out appendicitis from January to July
Results: Among 2015 ultrasonography scans 296 were performed to exclude a diagno-
sis of acute appendicitis. 288 could be interpreted and the diagnosis of acute appendi-
citis was established in 52. In 15 cases the ultrasonography and the definite diagnosis
differed. Ultrasonography and surgical diagnosis were different in 6 patients. In 9 pa-
tients the ultrasonography was not diagnostic. Ultrasound sensitivity, specificity, positi-
ve predictive value, and negative predictive value were 83.7%, 97.4%, 87.7% and
96.2%, respectively.
Conclusions: The global cost-effectiveness of ultrasonography to diagnose appendicitis
is good. Due to its availability and its low cost, ultrasonography is an accurate test for
the diagnosis of acute appendicitis in emergency departments, specially in uncertain
cases. [Emergencias 2008;20:81-86]
Key words: Acute appendicitis. Acute abdominal disorder. Ultrasonography.
ses of perforation and to 5-15% among the el-
Acute appendicitis (AA) is the most commonly
It is traditionally believed that acute appendici-
occurring abdominal acute condition in emer-
tis is caused by an infection due to an obstructive
gency departments1,2.
problem. The main cause for obstruction in 60%
It can present at all ages, although it occurs
of cases is hyperplasia of submucosal lymphoid fo-
more frequently during the 2nd and 3rd decades of
llicles. In 30-40% of cases, it is due to a faecalith
life. Although it is relatively rare among extreme
or appendicolith (rarely visible via x-ray), with the
age-groups, it is more complicated when it does
remaining 4% being attributed to foreign bodies.
occur, due to difficulty in pinpointing exact pain
In exceptional cases (1%), it is the form of pre-
location and in giving an accurate description of
sentation of appendicular tumours.
Typical symptoms include pain initially centred
The overall lifetime risk of deveopling ap-
in the epigastric region and subsequently moving
pendicitis is estimated to be of 7%. Around 1%
to the right iliac fossa (RIF), presenting along with
of outpatients presenting with abdominal pain
fever, nausea and vomiting, although this only oc-
have acute appendicitis (2.3% in the case of
curs in 70% of cases5.
children)3,4. The mortality rate in non-complica-
Until recently, surgical treatment was recom-
ted cases is of 0.3%, increasing to 1-3% in ca-
mended for any case of RIF pain with a reasona-
Emergencias 2008; 20: 81-86

R. Pintado Garrido et al.
ble suspicion of AA, which led to a very high rate
ploration area to displace the air from the intesti-
of unnecessary appendectomies (10-30%)6.
nal ansae and to minimise pain caused to the pa-
The main clinical problems currently posed by
tient, avoiding rebound pain due to successive
appendicitis are its significant rate of post-surgical
compression and decompression. High resolution
morbidity (18%)7 and that diagnostic and thera-
transducers, and occasionally Doppler-colour, are
peutic delay can lead to the onset of a histologi-
cally more severe appendicitis as a result of an in-
The ultrasonographic criteria used by the Ra-
creased risk of perforation6,8,9.
diology Department to diagnose acute appendici-
The highly accurate diagnostic imaging me-
tis were: identification of a tubular intestinal struc-
thods currently available help to improve the ma-
ture located in the lower right hemi-abdomen,
nagement of patients with suspected AA10. Both
closed at one end, with a transverse diameter ex-
ultrasound and CT scans have proven to be highly
ceeding 6 mm, not compressible and aperistaltic,
reliable methods for diagnosing appendicitis11, but
the appearance of appendicolith and/or the pre-
the indications and circumstances dictating which
sence of extra-appendicular alterations such as in-
method should be used remain subject to discus-
flamed peri-enteric fat, phlegmon or peri-appen-
sion3. The initial diagnostic imaging test in most
dicular abscess.
centres is ultrasonography6,12. This study assesses
Variables were compiled in Excel tables and
the need for ultrasonography in the diagnosis of
analysed and processed via the Windows SPSS
AA in an emergency department.
programme version 11.0. Discrete variables were
described using absolute frequencies (percenta-
ges) and continuous variables as means and stan-
dard deviations. The χ2 test (or Fisher exact test in
calculated values under 5) for discrete variables
This is a descriptive, observational and retros-
and the Student t test for continuous variables
pective study, involving the review of clinical his-
were applied when required. Statistical significan-
tories of patients attended in the emergency de-
ce was set at p < 0.05. Diagnostic performance
partment of our hospital from January to June
markers were sensitivity, specificity, positive pre-
2004. A total of 2015 emergency abdominal ul-
dictive value and diagnostic efficacy.
trasounds were performed during this period, 296
being requested for suspected AA.
Initial clinical assessments and ultrasound re-
quests were made in all cases by an emergency
department physician.
Pain in RIF with clinical suspicion of acute ap-
The following data were collected: epidemiolo-
pendicitis accounted for 15% of the emergency
gical (sex and age), clinical (pain in lower right
ultrasound explorations.
hemi-abdomen, fever, physical exploration and
Of the 296 emergency ultrasounds requested
analyses), ultrasonographic and histopathological.
due to suspected appendicitis, this diagnosis
The diagnosis of clinically suspected appendici-
could not be evaluated in 8 cases: 7 due to the
tis was made on the basis of pain in the lower
presence of abundant abdominal gas preventing
right hemi-abdomen and the presence or absence
adequate observation of intestinal ansae and in
of one or more of the following criteria: fever (de-
one case due to obesity. As for the 288 remaining
emed to be a body temperature at physical explo-
cases, the age ranged between 2 to 92 years (me-
ration above 37.5ºC), leukocytosis (>10.000 U/ml)
an 31.4 years) and 162 were women (56%) and
and Blumberg’s sign (pain following abdominal
126 men (44%).
Table 1 shows the various end diagnoses arri-
The final diagnosis was made comparing the
ved at for the patients following clinical assess-
ultrasonographic findings with the histopathologi-
ment and ultrasound performance. The diagnosis
cal study results, except for cases of appendiceal
of non-specific abdominal pain was the most fre-
adhesion masses for which post-surgical findings
quent of the pathologies found, accounting for
were taken into consideration. A clinical radiologi-
67% thereof.
cal follow-up was performed in non-surgical pa-
The diagnostic value obtained by the ultra-
sound is shown in Figure 1. The following results
The ultrasonographic exploration of the right
on ultrasound performance in the diagnosis of ap-
iliac fossa is performed by gradual compression:
pendicitis at our hospital were obtained: 83.7%
continuous, uniform pressure is applied to the ex-
sensitivity, 97.4% specificity, 87.7% positive pre-
Emergencias 2008; 20: 81-86

dictive value, 96.2% negative predictive value and
Table 1. Final clinical diagnoses following ultrasound
95% diagnostic efficacy (Figure 2).
performance in the 288 patients included in the study
The ultrasonographic findings in patients un-
Number of patients
dergoing diagnostic ultrasonography were: identi-
Non-specific abdominal pain
fication of a tubular structure exceeding 6 mm in
diameter (97.7%), abdominal free fluid (42.8%),
Gastrointestinal disorders
Gynaecological disorders
inflamed echogenic surrounding mesoappendix
(39.5%), presence of appendicolith (25.6%) and
appendiceal adhesions or abscess (6.9%).
In all cases in which the ultrasound was perfor-
At our hospital emergency department, in ca-
med for suspicion of acute appendicitis which was
ses with a medical history and physical explora-
subsequently not confirmed, the observations in-
tion suggestive of possible appendicitis, chest and
cluded a tubular structure over 6 mm, inflamed
abdominal radiography and blood analyses are
surrounding mesoappendix in 66.7%, free fluid in
routinely performed. Of all signs and symptoms,
33.3% and appendicolith in 16.7% of cases. The
only the presence of leukocytosis and a positive
final diagnosis in these cases was: non-specific ab-
Blumberg’s sign show a statistically significant as-
dominal pain in 3 cases, pelvic inflammatory dise-
sociation with the diagnosis of AA.
ase in 1 case, acute gastroenteritis in 1 case and
Thirty percent of clinical cases are atypical and
cecal diverticulitis in the last case.
confusing5, leading to diagnostic errors and an in-
Of the 9 false negative cases, 7 showed a to-
crease in the number of unnecessary laparotomies.
tally normal ultrasonographic exploration, free
This situation may prove particularly problematic
fluid was observed in the pelvis in one case and in
for women who may present with acute gynaeco-
the last case the ultrasound was performed for
logical symptoms which could, to a large extent,
suspected terminal ileitis. Of the true negatives
simulate those of acute appendicitis. It is in these
83% were finally diagnosed as non-specific abdo-
atypical cases where many studies6,14,15 show that
minal pain.
ultrasonography is useful in arriving at a diagnosis
of appendicitis, whilst proving less useful in pa-
tients with a high clinical probability of appendi-
citis who require immediate surgical assessment
and for whom any delay in treatment should be
Despite being one of the most frequent diag-
avoided to reduce potential complications.
noses among surgical emergencies, AA continues
Image testing on suspicion of AA should be
to pose significant diagnostic problems.
used as a diagnostic complement in selected cases
The diagnosis of AA in most cases is based on
and not as a routine tool in the initial clinical ex-
clinical history and physical exploration13.
Ultrasounds for suspected
49 (17%)
239 (83%)
43 (88%)
6 (12%)
230 (96%)
9 (4%)
Figure 1. Results of ultrasounds performed.
Emergencias 2008; 20: 81-86

R. Pintado Garrido et al.
A great number of studies6,14,17,18 recommend
that if clinical findings still suggest appendicitis
despite negative ultrasound results, the patient
should remain under hospital observation and
subject to clinical exploration and, in some cases,
successive ultrasonographies and even surgery.
It must not be forgotten that the ultrasonogra-
phic results of the physician performing the test
since the results may vary between those of an in-
experienced physician and those of one familiar
with the test, often explaining the false negatives
and positives reported, and the lower number of
false results obtained by more experienced ultra-
sound physicians12,17,19.
Figure 2. Calculation of sensitivity, specificity, positive and
The diagnostic values obtained in this study
negative predictive values and diagnostic accuracy.
are similar to those published to date1,11.
Another complementary imaging test that can
The only specific sign of AA that can be obser-
be performed for an emergency diagnosis of AA is
ved via a simple abdominal radiography is the
Computed Tomography (CT). The higher sensiti-
presence of appendicolith (provided there are
vity provided by CT makes it more useful accor-
other compatible symptoms). Other signs yielded
ding to various studies9,13,14 when diagnosing AA.
by abdominal radiography, such as the presence
Moreover, CT is less painful and offers a better
of a dilated ansa, hydroaerial levels, antalgic sco-
performance in the diagnosis of other abdominal
liosis and erased psoas, are less specific9.
diseases, thus leading to many more alternative
Another complementary method is abdominal
diagnoses9,13. Its main disadvantages are a higher
ultrasonography, which in our case is usually the
radiation level, higher cost and the need, accor-
final diagnostic test. Among our patients we have
ding to some authors, to use contrast material9.
confirmed the usefulness of ultrasonography as a
We believe that the use of CT is advisable in
diagnostic confirmation test (high positive predic-
cases of inconclusive results from analyses, routine
tive value, negative predictive value and specifi-
radiographies and ultrasonographies performed,
city). Observation of an enlarged and non-com-
as well as in the case of an evolutive or complex
pressible appendix is a sign of high positive
disease, as it enables a more reliable detection of
predictive value. Nevertheless, the main difficulty
the presence of appendicular adhesions or abs-
posed by appendicitis ultrasound lies in elimina-
cess, and particularly in the elderly, for whom the
ting the presence thereof. The usual negative
risk of radiation exposure is minimal. In most of
diagnostic criterion (lack of visual appreciation of
the cases in our series, the ultrasound proved suf-
an inflamed appendix) may be due to the non-
ficient to achieve a diagnosis as has been shown
existence of appendicitis or to the impossibility of
in the results, moreover offering the possibility of
confirmation thereof which has often led to nega-
making alternative diagnoses20.
tive predictive ultrasound values to be lower that
We believe that the false positives obtained are
the positive values7. The literature reports a rate of
related to the inexperience of the ultrasonogra-
perforated acute appendicitis of 21%16, but the
pher performing the test plus the fact that many
existence of false negatives rises to 44% due to
appendicitis cases do not undergo surgical inter-
the reduction in sensitivity caused by the perfora-
vention but rather are treated with antibiotics.
tion, that is, the identification of a non-compressi-
We consider that the false negatives obtained are
ble tubular structure of a +6 mm. diameter – the
related to appendicular perforation, as in such ca-
ultrasonographic sign most indicative of appendi-
ses the sensitivity is reduced due to the enlarged
citis2 – is no longer visible as it becomes concea-
tubular structure being less visible. This hypothe-
led within the adhesion mass that is formed by
sis, however, has not been tested in our study.
the perforation. Another cause of ultrasound false
We thus conclude that abdominal ultrasono-
negatives is the precocity in many cases when
graphy is the most useful complementary explora-
performing the test17. It is therefore very impor-
tion in emergency departments for diagnosing
tant to interpret the ultrasonography in each indi-
acute appendicitis (95% accuracy) especially in
vidual clinical context, particularly in cases in the
cases of doubtful diagnosis. The accessibility and
early stages.
low cost of this approach make it ideal for emer-
Emergencias 2008; 20: 81-86

gency diagnosis, offering high levels of sensitivity
abdominal pain: diagnostic strategies. Eur Radiol
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sential in the study of acute appendicitis, as it
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unnecessary laparotomies.
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Indicación y utilidad de la ecografía urgente en la sospecha de apendicitis aguda
Pintado Garrido R, Moya de la Calle M, Sánchez Ramón S, Castro Villamor MA, Plaza Loma S, Mendo González M
Objetivo: La apendicitis aguda es la patología quirúrgica aguda abdominal más frecuente. Su diagnóstico constituye
uno de los problemas más habituales en los servicios de urgencias. El objetivo del presente estudio es evaluar la utili-
dad de la ecografía abdominal en el diagnóstico de esta entidad.
Método: Estudio retrospectivo realizado entre enero y junio del 2004 de todas las consultas realizadas en el servicio de
urgencias por dolor abdominal indicativo de probable abdomen agudo, en los que se realizó una ecografía abdominal
para descartar apendicitis aguda.
Resultados: Se realizaron 2.015 ecografías abdominales urgentes de las cuales 296 fueron solicitadas para descartar el
diagnóstico de apendicitis aguda, de éstas 288 fueron valorables. En 52 pacientes la ecografía fue indicativa de apendi-
citis aguda. En 15 casos el diagnóstico ecográfico fue discordante con el diagnóstico final. En 6 pacientes el informe
ecográfico de apendicitis no se confirmó a posteriori. En 9 casos la ecografía fue no diagnóstica pese al diagnóstico
quirúrgico de apendicitis aguda. Con estos datos, el rendimiento global de la ecografía para el diagnóstico de apendi-
citis aguda, se tradujo en una sensibilidad del 83,7%, especificidad del 97,4%, valor predictivo positivo del 87,7%, va-
lor predictivo negativo del 96,2%.
Conclusiones: El rendimiento global de la ecografía abdominal en el diagnóstico de apendicitis aguda en nuestro me-
dio es aceptable. Debido a su accesibilidad y bajo coste es la prueba idónea para el diagnóstico en urgencias, sobre to-
do en casos dudosos. [Emergencias 2008;20:81-86]
Palabras clave: Apendicitis aguda. Abdomen agudo. Ecografía abdominal.
Emergencias 2008; 20: 81-86