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ABSTRACT
DIAGNOSTIC ACCURACY OF COMPUTED TOMOGRAPHY (CT) IN
DETECTING THE CAUSE OF OBSTRUCTION IN BILIARY OBSTRUCTIVE
DISEASE COMPARATIVE EVALUATION WITH ENDOSCOPIC
RETROGRADE CHOLANGIOPANCREATOGRAPHY (ERCP)
Statement of the Problem
The study aims to assess the accuracy of CT in detecting the cause of
obstruction in biliary obstructive disease in comparison with ERCP. Specifically thestudy sought the answers to the following questions:
1. What is Computed tomography ?
2. What is endoscopic retrograde cholangiopancreatography?
3 .What is diagnostic accuracy of CT in detecting causes of biliary obstructive
disease compared with ERCP in terms of :
a. Sensitivity
b. Specificity
c. Detection accuracy
Methodology
The study employed semi-systematic literature review was employed in the
study. An electronic search was performed using a wide range of data base in order to
obtain the information for the progress of the study. Each study was carefully reviewed
for their content and relevance to present investigation.
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Summary of Findings
1.What is Computed Tomography (CT)
CT or computed tomography is a diagnostic imaging procedure that uses x-rays
to obtain cross-sectional images. It is a non-invasive procedure that aid in the correct
diagnosis of biliary obstructions among others. Among the risks in CT procedure to
patients are possible allergy from contrast agent used in some cases and lifetime
exposure to radiation adverse health effects like hair loss, skin injury among others.
2. What is Endoscopic retrograde cholangio pancreatography
(ERCP).
Endoscopic retrograde cholanagiopacreatography is both a diagnostic and
therapeutic tool. Endoscopic refers to a thin, flexible tube with a tiny video camera and
light at the end, while retrograde refers to the direction in which the endoscope is used
to inject a liquid enabling X-rays to be taken of the parts of the GI tract called the bile
duct system and pancreas. ERCP is an invasive diagnostic modality indicated in
detecting biliary obstructions.
3 .What is accuracy rate of CT in detecting causes of biliary obstructive disease
compared with ERCP ?
a. Sensitivity
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Except with two studies the sensitivity rate of ERCP is consistently higher
compared with that of CT rate in detecting obstructive jaundice, biliary strictures,
common bile duct stones, choledochal stones and pancreatitis.
b. Specificity
Studies have shown that ERCP is superior to CT specificity-wise in detecting
causes of obstruction biliary strictures, jaundice and common bile duct stones, but is
out-performed in one case that involves detection of pancreaticobiliary.
c. Detection Accuracy
In all biliary obstructions examined by four studies indicate that only choledochal
cysts, bile duct injury had CT in equal footing with ERCP. But detecting gallbladder
stones, intrahepatic bile duct stones except with 1 study; choledocholithaiasis,
pancreatobiliary tumor, gallbladder carcinoma; pancreatic head carcinoma, bile papilla
carcinoma and chronic pancreatic, CT remains inferior to ERCP.
Conclusions
1. Computed tomography is a non-invasive diagnostic imaging procedure that
aided diagnosis and detection of some biliary obstructions.
2. Endoscopic retrograde cholangiography is an invasive diagnostic imaging tool
and therapeutic instrument for diagnosing and detecting biliary obstruction.
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3. In comparison between CT and ERCP, CT has lower sensitivity rate
compared to ERCP in detecting biliary obstructions like choledochal stones, obstructive
jaundice, biliary strictures; common bile duct stones and biliary pancreatitis.
5. In terms of specificity ERCP is found superior among diagnostic imaging
modalities including CT. Only 1 studies had found out that CT has 100% specificity in
detecting pancreatico biliary as against 91.7% of ERCP . The rest the studies showed
that ERCP remains superior with CT in terms of specificity rate in detecting obstructive
jaundice, biliary strictures and common bile duct stones.
6. In terms of detection accuracy, studies reviewed indicated the consistently
high accuracy rates of ERCP over CT.
Recommendations
The researcher recommends local studies on the clinical values of different
diagnostic imaging tools in view of rising cases of obstructive biliary disease in the
country.
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CHAPTER I
THE PROBLEM AND ITS BACKGROUND
Introduction
In any type of disease exact diagnosis is essential for proper medical
management and treatment. This is very important especially when the presenting
symptoms need immediate attention and could endanger the life of the patient. There
are diseases that could not be detected or diagnosed by auscultation alone. Different
diagnostic imaging modalities are used for accurate diagnosis of diseases. These tools
are used in examining diseases in the internal organs.
Diagnostic imageological tools are either invasive or non-invasive types.
Sometimes both types are used when initial diagnosis is doubtful. These tools greatly
aid in the diagnosis of internal organs like the bile duct. Bile duct is any of a number of
long tube-like structures that carry bile. Bile is required for the digestion of foods is
excreted by the liver into passages carrying it toward the hepatic duct which joins with
the cystic duct to form the common bile duct that opens into the intestine. The biliary
tree is the whole network of various sized ducts branching through the liver
(www.wikipedia.com). Several problems and abnormalities can arise from the bile
ducts. There are many causes of biliary obstruction. In recent years saw a rapid and
continuous evolution in the diagnosis of biliary obstructive disease (Ferrari, 2005).
These tools include invasive and non-invasive types. These include traditional
methodologies such as ultrasonography (US); computed tomography (CT), endoscopic
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retrograde cholangiopancreatography (ERCP), percutaneous transhepatic
cholangiography) magnetic resonance cholangiopancreatogaphy (MRCP) and other
modalities which are improvement of the existing ones.
In this study, the focus of interest lies between computed tomography (CT) and
endoscopic retrograde cholangiopancreatography (ERCP). The main objective of the
study is to assess the diagnostic accuracy of CT in detecting causes of biliary
obstructive disease compared with ERCP.
Conceptual Framework
Diagnostic tests and examinations are used to confirm, exclude or classify the
location, severity, size, shape or other clinically meaningful subgroups of disease in
order to guide treatment, indicate prognosis or monitor progress. These tests are also
indicated in cases when clinical history and examination provide insufficient information
to distinguish a disease/s from a set of candidate diseases (differential diagnoses) or to
plan management. The results of these tests may lead to a decision threshold for a
given diagnosis or it may lead to further testing. In the case of biliary obstruction,
clinical decision-making is particularly complex, due to the wide range of differential
diagnoses including pancreaticobiliary disease that may need to be considered and the
potentially high penalty of delayed treatment if the cause is not detected in a timely
fashion (MSAC,2005).
In making diagnosis concerning biliary obstructive disease, there are a number
of diagnostic modalities available that includes CT and ERCP. Determining the
outcomes of the results of these test predetermined the health outcomes. However,
the outcomes depends on the accuracy of the test results with reference to sensitivity,
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specificity, and accuracy of detection. In the study, rate of sensitivity, specificity, level of
detection are predictors of accuracy of diagnosis of causes of biliary obstruction.
Statement of the Problem
The study deals with an evaluation of diagnostic accuracy CT in detecting causes
of biliary obstructive disease in comparison with ERCP. Specifically, the study aims to
answer the following questions:
1. What is Computed tomography ?
2. What is endoscopic retrograde cholangiopancreatography?
3 .What is diagnostic accuracy of CT in detecting causes of biliary obstructive
disease compared with ERCP in terms of :
a. Sensitivity
b. Specificity
c. Detection accuracy
Significance of the Study
Accurate diagnosis is essential in making informed decisions about the therapy
and treatment of diseases. The cost of wrong diagnosis is very high and at extreme
fatal for the patients and devastating for the doctors and the institutions. In the case of
diagnosing biliary obstruction, several imaging tools or modalities are available to aid
the doctors to come up with the correct and accurate diagnosis. The results of the tests
predetermined the outcome of the treatment. Computed tomography and endoscopic
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retrograde cholangiopancreatography are but two of the diagnostic tools in detecting
biliary obstruction and causes. Understanding the clinical value of each type will
increase the readers knowledge and help doctors decide which of the two type will be
effective in making informed clinical decisions regarding the patients conditions which
ultimately benefit the patients. Hence, the significance of the study.
Definition of Terms
These terms are used in the study. For clarity and appreciation of the present
study, these terms are defined:
Computed Tomography (CT). In the study refers to both plain and improved
typed OF diagnostic imaging tool in detecting biliary
obstruction. It is a cross-sectional representation of anatomy that is constructed by a
computer from the signals generated by x-ray beams passing through the body from
different directions (MASC,2005).
Diagnostic accuracy. As used in the study refers to the correctness of the results
of the tests using CT and ERCP.
Endoscopic retrograde cholangiopancreatography (ERCP). It is another
diagnostic tool for detecting biliary obstruction. It is an invasive tool that can also be
used for therapeutic intervention (MASC,2005).
Negative predictive value. It refers to the proportion of patients with negative test
results who are correctly diagnosed (www.wikipedia.com).
Positive predictive value. Defined as proportion of patients with positive test
results who are correctly diagnosed (www.wikipedia.com).
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Sensitivity. One of the predictors of diagnostic accuracy refers to how many
cases of a disease a particular test can find (Boring 1990).
Specificity. Another diagnostic accuracy predictors in the study, refers to how
accurately it diagnoses a particular disease without giving false positive results.
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CHAPTER II
REVIEW OF RELATED LITERATURE AND STUDIES
Related Literature
The following is extracted from an assessment report prepared by the Medical
Service Advisory Committee of Australia that is found relevant to the present study on
accuracy of detection of diagnostic imaging modalities such as computed tomography
(CT) and endoscopic retrograde cholangeopancreatography (ERCP).
Normal function of the bile ducts and pancreas
Bile is a liquid produced by the liver that contains bile salts, cholesterol, lipids and waste
products, such as the pigment bilirubin. It is needed for the digestion and absorption of
fats and fat-soluble vitamins. The normal function of the bile ducts is to transport bile
from the liver to the gallbladder, where it is stored and concentrated, and then it is
released into the duodenum where it aids digestion. The bile is transported from the
gallbladder to the duodenum via the common bile duct through the valvular opening of
the sphincter of Oddi at the ampulla of Vater. After eating, the entrance of fat or protein
into the small intestine triggers the secretion of a hormone called cholecystokinin, which
stimulates contraction of the gallbladder and the opening of the sphincter of Oddi so that
bile may pass into the duodenum.
The pancreas is a small gland that lies behind the stomach and is surrounded by
the intestines and liver. Normal function of the pancreas is essential for the production
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of hormones such as glucagon and insulin that are released into the blood stream to
regulate blood glucose levels as well as enzymes that are released into the duodenum
for digestion. The pancreas also produces digestive enzymes and these enter the
duodenum from the pancreatic duct via the Ampulla of Vater to aid digestion.
Diseases associated with obstruction of the bile or pancreatic ducts
Pancreaticobiliary diseases (not including patients with associated gallbladder
disease) accounted for 19,552 hospital separations in Australia over the 12-month
period from 2002-2003. As described on page 10, common clinical presentations where
MRCP may be indicated include patients with symptoms or signs due to biliary
obstruction as a result of bile duct stones or strictures due to cancer, inflammation or
other benign causes.
Surgical treatment for bile duct stones and localised benign strictures is often
curative. If untreated, biliary obstruction can lead to fulminant infection (cholangitis) and
death. Long-term obstruction can also lead to chronic liver disease.
Stones in the common bile duct
Common presenting symptoms of bile duct stones are acute pain, jaundice and
sometimes fever due to cholangitis (infection of the duct) with or without sepsis (Ko &
Lee 2002). Bile duct stones may also be a cause of symptoms in patients who have had
their gallbladder removed as described below.
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Post-cholecystectomy syndrome
Post-cholecystectomy syndrome is a term used to describe the presence of
symptoms following cholecystectomy, that can be attributed to the gallbladder or its
removal. These symptoms include pain, nausea, vomiting and jaundice. In some cases,
these patients require further investigation to exclude biliary causes including common
bile duct stones.
Strictures of the bile duct
Strictures of the bile duct may be due to malignancy or benign causes. Further
imaging of the bile duct is indicated if ultrasound and CT scans are equivocal and may
also be used to determine the extent of the stricture for disease staging and planning
management .
Cancer of the pancreas
Ductal adenocarcinoma is the most common type of pancreatic cancer. Common
symptoms include jaundice, abdominal pain and weight loss. Primary cystic tumours are
rarer and more likely to be identified in asymptomatic patients incidentally. Although
rare, the detection and accurate differentiation between benign and malignant cystic
tumours and the extent of disease are critical to plan appropriate treatment.
Cholangiocarcinoma
Cholangiocarcinoma may arise in the bile ducts within the liver (intrahepatic, 10%
of cases) or outside the liver (extrahepatic), including at the hepatic hilus. Incidence of
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this uncommon cancer increases with age and the diagnosis is usually made in patients
over 60 years of age presenting with jaundice and in some cases, abdominal pain,
pruritus and weight loss. Early onset may occur in patients aged between 40 and 60
years with risk factors such as primary sclerosing cholangitis and choledochal cysts.
Cancer of the ampulla of Vater
Ampullary cancer was the primary diagnosis at discharge for 278 patients
hospitalised in Australia in 2002-2003 (Table 3). It presents with biliary obstruction but
also may present with cholangitis or pancreatitis. The early detection of this disease and
distinction from cancer of the pancreas or second part of the duodenum are important
because management is different and early surgery can be curative..
Pancreatitis
Pancreatitis refers to acute, chronic or relapsing inflammation of the gland.
Typical symptoms are abdominal pain, jaundice, malaise and vomiting. Blood tests
show raised pancreatic enzymes. The commonest causes of acute pancreatitis are
gallstone obstruction of the pancreatic duct and alcohol abuse. It also occurs as a
complication of ERCP. Recovery with supportive treatment is usually uneventful;
however, in 10-15% of patients it can be complicated by a systemic inflammatory
response and lead to pancreatic necrosis, which has a high mortality rate.
Chronic pancreatitis is characterised by permanent damage to the gland.
Treatment of chronic pancreatitis involves the management of pain and malabsorption
due to insufficient pancreatic enzymes. In the long term, up to 50% of patients require
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treatment of diabetes. Complications include inflammatory cysts (pseudocysts),
pancreatic stones, pancreatic or biliary duct strictures, duodenal stenosis, portal
hypertension and an increased risk of pancreatic cancer .
Related Studies
Jang, Chong, and Kim (2010) studied the safety of performing ERCP in young
children from Korea. The researchers concluded that ... diagnostic and therapeutic
ERCPs were performed safely and effectively in Korean children for the management of
various biliary and pancreatic diseases. Pediatricians and pediatric surgeons, especially
those working in Asian countries, should become more familiar with ERCP as a
diagnostic and therapeutic modality, as Asia has a high incidence of CCs and
anomalous union of the pancreaticobiliary duct.
According to Chong, Yin and Lim (2005) ERCP is a potentially life-saving
intervention in the elderly population. Our study showed that ERCP is safe in the elderly
Asian populations. In conclusion, our study showed that ERCP is safe in the elderly
Asian population. Minor complications are usually transient and related to sedation, and
mortality is usually related to severity of illness and underlying malignancies. ERCP
should be considered when indicated in the elderly population as this may be life
saving.
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CHAPTER III
METHODOLOGY
Research Design
The study is a qualitative literature review. It utilized relevant research that has
been done on the same field. The results of these studies were extracted to obtain the
relevant data necessary to answer the questions raised in the study.
Selection of the Studies
Studies selected in the study are those that involved comparison of imaging
modalities for detecting biliary obstruction that includes CT and ERCP. The studies
selected includes all or any of the predictors used by the present study in making
comparative evaluation of CT with ERCP. The present study employed a deliberate
sampling of studies was based on the criteria that studies involves an assessment of
different diagnostic imaging modalities for biliary obstructions that include CT and ERCP
and that the assessment includes all or any of the predictors set for comparing and
evaluation of both imaging modalities. Eleven studies qualified on the criteria set for
inclusion in this research.
Data Gathering Procedure
An electronic search was performed using a wide range of data base in order to
obtain the information for the progress of the study. Each study was carefully reviewed
for their content and relevance to present investigation. Twenty-five potential studies
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were screened and initially assessed. Out of these 4 studies were rejected for the title;
the abstract of the remaining 21 were screened and out of these 5 were rejected. The
full content of the 16 studies were read and screened. Two studies were rejected.
Fourteen selected were found potentially relevant and but 3 were rejected for quality.
Finally eleven studies were selected and employed as primary source of data in the
present research.
Data Analysis
The data gathered from the studies selected in the study were assessed
according to the criteria set in the present study. As previously mentioned studies must
include an evaluation of diagnostic modalities for biliary obstruction that includes CT
and ERCP. These studies must include all or any of the data on the rate of sensitivity,
specificity, rate of positive and negative predictive values and rate of detection.
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CHAPTER IV
PRESENTATION, ANALYSIS AND INTERPRETATION OF DATA
This chapter presents the results of the literature review on the diagnostic
accuracy of CT in detecting causes of biliary obstruction in comparison with ERCP.
What is Computed Tomography (CT)
CT is a diagnostic imaging procedure that uses x rays to obtain cross-sectional images
of the body. Since its introduction and rapid adoption into medicine in the mid-1970s,
CT has become recognized as a valuable medical tool for the diagnosis of disease,
trauma, or abnormality and for planning, guiding, and monitoring therapy
(www.wiki.medpedia,com).
1. A motorized table moves the patient through a circular opening in the CT imaging
system.
2. While the patient is inside the opening of the CT imaging system, an x-ray source
and detector within the housing rotate around the patient. A single rotation takes
about 1 second. The x-ray source produces a narrow, fan-shaped beam of x-rays
that passes through a section of the patient's body.
3. A detector opposite from the x-ray source records the x-rays passing through the
patient's body as a "snapshot" image. Many different "snapshots" (at many
angles through the patient) are collected during one complete rotation.
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4. For each rotation of the x-ray source and detector, the image data are sent to a
computer to reconstruct all of the individual "snapshots" into one or multiple
cross-sectional images (slices) of the internal organs and tissues (like the biliary
ducts).
As in any diagnostic procedures, CT is not risk free. Among the main risks
associated with CT ARE:
1. An increased lifetime risk of cancer due to x-ray radiation exposure.
2. Since the procedure in some cases involves use of contrast agent or dye,
there is a possible allergic reactions or kidney failure.
3. The need for additional follow-up tests after receiving abnormal test
results or to monitor the effect of a treatment on disease, such as to
monitor a tumor after surgical removal. Some of these tests may be
invasive and present additional risks.
4. Under some rare circumstances of prolonged, high-dose exposure, x-rays
can cause other adverse health effects, such as skin reddening
(erythema), skin tissue injury, hair loss, cataracts, and potentially, birth
defects (if scanning is done during pregnancy).
Radiation exposure is a concern in both adults and children. However, these
concerns are greater for children because they are more sensitive to radiation and have
a longer life expectancy than adults. As a result, accumulated exposures over a childs
lifetime are more likely to result in an adverse health effect. A childs smaller size also
has an impact on the radiation dose they receive. For example, if a CT scan is
performed on a child using the same parameters as those used on an adult, an
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unnecessarily large dose will be delivered to the child. CT equipment settings (exposure
parameters such as, x-ray tube current, slice thickness, or pitch) can be adjusted to
reduce dose significantly while maintaining diagnostic image .quality(www.hhs.gov.).
What is Endoscopic retrograde cholangio pancreatography (ERCP)
The term endoscopic refers to the endoscope which is a thin, flexible tube with a
tiny video camera and light on the end. The endoscope is used by a highly trained
subspecialist, the gastroenterologist, to diagnose and treat various problems of the GI
tract. The GI tract includes the stomach, intestine, and other parts of the body that are
connected to the intestine, such as the liver, pancreas, and gallbladder.
Retrograde refers to the direction in which the endoscope is used to inject a
liquid enabling X-rays to be taken of the parts of the GI tract called the bile duct system
and pancreas. The process of taking these X-rays is known as
cholangiopancreatography. Cholangio refers to the bile duct system, pancrea to the
pancreas.
ERCP is indicated for the following:
Gallstones which are trapped in the main bile duct
Blockage of the bile duct
Yellow jaundice which turns the skin yellow and the urine dark
Undiagnosed upper-abdominal pain
Cancer of the bile ducts or pancreas
Pancreatitis
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The main symptoms of pancreatitis are acute, severe pain in the upper abdomen,
frequently accompanied by vomiting and fever. The abdomen is tender, and the patient
feels and looks ill. The diagnosis is made by measuring the blood pancreas enzymes
which are elevated. A sound wave test (ultrasound) or abdominal CT exam often shows
an enlarged pancreas. The condition is treated by resting the pancreas while the tissues
heal. This is accomplished through bowel rest, hospitalization, intravenous feeding and,
pain medications.
When pancreatitis is caused by gallstones, it is necessary to remove the
gallbladder. This is usually done after the acute pancreatitis has resolved. At times, an
ERCP (Endoscopic Retrograde CholangioPancreatography) test is recommended. This
involves passing a flexible tube through the mouth and down to the small intestine. A
small catheter is then inserted into the bile duct to see if any stones are present. If so,
they are then removed with the scope (http://www. e-
radiography.net/technique/ercp/ercp.htm).
3 .What is accuracy rate of CT in detecting causes of biliary obstructive disease
compared with ERCP ?
a. Sensitivity
In a study comparing CT and ERCP in pancreatibiliary disease, Tobin and his co-
authors(2004) found CT to be superior than ERCP in terms of sensitivity having 100%
sensitivity rate compared to 91.7 of the later. But in a study by Pasanen et al (1992) of
diagnositic accuracy in diagnosis of choledochal stones, ERCP performed better with a
sensitivity rate of of 80.6% compared to CTs 23.2%. Tobins et al. study involved only
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57 patients; while that of Pasanen et all consisted of 220 patients. Meanwhile in the
study of Pasanen et al in diagnosis of cholestasis among 220, CT fared better with 97%
compared with ERCP 89%.. Meanwhile in a study comparing with CT among others,
Vipul and Dy, found out that in more than 3000 patients, ERCP performed better in
diagnosing common bile duct stones with 79-93% sensitivity rate compared to CTs 71-
75% rate.
On the other hand a study comparing diagnostic accuracy among different
modalities including CT and ERCP in diagnosing biliary strictures, Rosch, et al (2002),
ERCP has 85% sensitivity rate compared to CTs 77%. The study involved 50 patients.
Pasanen, et al (1991) compared the diagnostic accuracy in obstructive jaundice of CT
and ERCP among others in 187 jaundiced patients. The results indicate that the
sensitivity rate of ERCP is greater at 87% than CTs 77%. In the study of Jong, et al
(2002) ERCP exhibited 90% sensitivity compared to only 40% of CT in biliary
pancreatitis.
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TABLE 1. STUDIES COMPARING CT AND ERCP IN TERMS OF
SENSITIVITY
StudyNo. of Patients
Biliary
Obstruction
Sensitivity
CT(%)
ERCP(%)
Tobin,Vogetzang,Gore andKeigley 57
PancreaticoBiliary 100 91.7
Pasanen, P., et al220 Choledochal
Stones 23.3 80.6
Pasanen, P. et al 220 Cholectasis 97 87
Pasanen, P. et al. 187ObstructiveJaundice 77 87
Rosch,T. Meining,A. et al. 50 BiliaryStrictures 77 85
Rathod, V and Dy, Frederick 3000CommonBile ductStones 71-75 79-93
Moon, Cho et al. 32Biliary
pancreatitis 40 90
b. Specificity
In a study of Rathod and Dy, the specificity value of ERCP is 92-100% which is
greater than the specificity value of CT which is 78-97% in detecting common bile duct
stones. The same trend is noted in the study of Rosch et al (2002). as the specificity of
ERCP is 75% which is greater than the specificity of CT which is 63% in biliary
strictures
Tobin and his associates (2004) declared in their study that in terms of
specificity, ERCP is 100% in diagnosing pancreaticobiliary disease compared to 91% of
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CT. Whereas in a study of 220 patients, Pasanen, et al (1992) claimed that in
diagnosing cholestasis ERCP specificity level is 94% while that of CT is 92%.
TABLE 2. STUDIES COMPARING CT AND ERCP IN TERMS OF
SPECIFICITY
Study No. of Patients BiliaryObstruction
Specificity
CT(%)
ERCP(%)
Tobin,Vogetzang,Gore andKeigley 57Pancreatico
Biliary 100 91.7
Pasanen, P. et al. 187ObstructiveJaundice 92 94
Rosch,T. Meining,A. et al. 50 BiliaryStrictures 63 75
Rathod, V and Dy, Frederick 3000CommonBile ductStones 78-97 92-100
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c. Detection Accuracy
TABLE 3. STUDIES COMPARING CT AND ERCP
IN TERMS OF DETECTION ACCURACY
StudyNo of
PatientsBiliary
Obstruction(Causes)
CT(%)
ERCP(%)
Zhong,Yao,Li & Xu 82 Gallbladder stone 75.0 80.0
Upadhaya, et al
Zhong,Yao, Li & Xu
100
82
Intrahepatic bileduct stone
85.71
100.0
95.83
100.0
Zhong,Yao,Li & Xu 82 Choledocholithiasis
88.2 94.1
Yang,Ping, et al; 58 Pancreato-biliarytumor
80 92
Zhong,Yao,Li & Xu Gallbladdercarcinoma
75.0 60.0
Wei-Xing et al.,
Zhong,Yao,Li & Xu
41
82Ampullarycarcinoma
84
50.
100
100
Zhong,Yao,Li & Xu 82Pancreatic headcarcinoma 81.8 100
Zhong,Yao,Li & Xu 82Bile papillacarcinoma 66.7 100
Zhong,Yao,Li & Xu 82 Bile duct injury
100. 100
Zhong,Yao,Li & Xu 82 Choledochal cyst
100 100
Zhong,Yao,Li & Xu 82Chronicpancreatitis 75.0 100
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In a study by Zhong, Yao, Li and XU (2003) they evaluate the clinical values of
various imageological methods including CT and ERCP in diagnosing the pancreato-
biliary diseases. The results of their study indicate that the accurate rate in detection of
biliary obstructions such as gallbladder stones for CT 75% and for ERCP is 80%;
intrahepatic bile duct stone is 100% for both methods, but the trend is different from
the study of Upadhaya et al (2006) where ERCP remains superior with accuracy rate of
95.83 as against 85.7% for CT. Zhong, and his associated noted the accuracy of ERCP
and CT in detecting Choledocholithiasis where ERCP remains superior with 94.1% rate
as compared to 88.2% rate for CT.where Zhong et al is 88.2 % for CT and 94.1%; The
same trend is noted by the authors in detecting pancreatic carcinoma(CT-81.8; ERCP-
100%); bile papilla carcinoma (CT-66.7% and ERCP -100%); and chronic pancreatitis
with accuracy rate of 75% for CT and 100% for ERCP. However, the authors show that
both modalities have the same accuracy rate in detecting choledochal cyst and bile duct
stones with 100%. Meanwhile the accuracy rate of detecting pancreato-biliary tumour,
Yang-Ping et al (2007), find ERCP superior with 92% as against 80% rate of CT. In the
study of Wei-Xing, et al found the accuracy rate of ERCP in detecting ampullary
carcinoma to be 100% as against 84% of CT. The same trend is noted in the study of
Zhong, Yao, Li and Xu (2003) where CT accuracy rate is documented as 50% and that
of ERCP as 100%.
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CHAPTER V
SUMMARY, CONCLUSIONS AND RECOMMENDATIONS
This chapter is the culminating part of the study. It presents the summary of
findings, conclusions and recommendations.
Summary of Findings
1.What is Computed Tomography (CT)
CT or computed tomography is a diagnostic imaging procedure that uses x-rays
to obtain cross-sectional images. It is a non-invasive procedure that aid in the correct
diagnosis of biliary obstructions among others. Among the risks in CT procedure to
patients are possible allergy from contrast agent used in some cases and lifetime
exposure to radiation adverse health effects like hair loss, skin injury among others.
2. What is Endoscopic retrograde cholangio pancreatography
(ERCP).
Endoscopic retrograde cholanagiopacreatography is both a diagnostic and
therapeutic tool. Endoscopic refers to a thin, flexible tube with a tiny video camera and
light at the end, while retrograde refers to the direction in which the endoscope is used
to inject a liquid enabling X-rays to be taken of the parts of the GI tract called the bile
duct system and pancreas. ERCP is an invasive diagnostic modality indicated in
detecting biliary obstructions.
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3 .What is accuracy rate of CT in detecting causes of biliary obstructive disease
compared with ERCP ?
a. Sensitivity
Two studies that of Tobin, and Pasanen had indicated that CT has higher level of
sensitivity rate in detecting pancreatico biliary; and cholectasis; compared with ERCP;
however the rests of the 7 studies reviewed indicated that the accuracy rate of ERCP is
consistently higher than CT in detecting obstructive jaundice, biliary strictures; common
bile duct stones, Choledochal stones and biliary pancreatitis.
b. Specificity
According to three studies reviewed the level of specificity of CT is lower in
diagnosing obstructive jaundice; detecting biliary strictures and common bile duct
stones compared with the rate of ERCP; but is found higher than the later in detecting
pancreaticobiliary.
c. Detection Accuracy
In all biliary obstructions examined by four studies indicate that only choledochal
cysts, bile duct injury had CT in equal footing with ERCP. But detecting gallbladder
stones, intrahepatic bile duct stones except with 1 study; choledocholithaiasis,
pancreatobiliary tumor, gallbladder carcinoma; pancreatic head carcinoma, bile papilla
carcinoma and chronic pancreatic, CT remains inferior to ERCP.
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Conclusions
1. Computed tomography is a non-invasive diagnostic imaging procedure that
aided diagnosis and detection of some biliary obstructions.
2. Endoscopic retrograde cholangiography is an invasive diagnostic imaging tool
and therapeutic instrument for diagnosing and detecting biliary obstruction.
3. In comparison between CT and ERCP, CT has lower sensitivity rate compared
to ERCP in detecting biliary obstructions like choledochal stones, obstructive jaundice,
biliary strictures; common bile duct stones and biliary pancreatitis.
5. In terms of specificity ERCP is found superior among diagnostic imaging
modalities including CT. Only 1 studies had found out that CT has 100% specificity in
detecting pancreatico biliary as against 91.7% of ERCP . The rest the studies showed
that ERCP remains superior with CT in terms of specificity rate in detecting obstructive
jaundice, biliary strictures and common bile duct stones.
6. As to detection accuracy, ERCP had been proven by studies reviewed to
remain the gold standard for diagnosis of biliary obstruction.
Recommendations
The researcher has noted in the course of researching for studies, there has
been no local studies on the subject. It is believed that cases obstructive biliary disease
is increasing in the country. And the need for accurate diagnosis for biliary obstructions
demands the need for adequate knowledge among our doctors of clinical values of
different diagnostic imaging tools. For this reason, the researcher recommends studies
on the subject beyond systematic literature reviews.
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Figure 1. Pathway flow
of diagnosing causes of
cholestatic jaundice
source:www.ima in athwa s.health.wa. ov.
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APPENDIX B
SUMMARY OF SELECTION PROCESS
Potentially relevant
studies identified
and screened
n = 25
Total abstract
screenedn=21
Total full paper
screened
n=16
Studies potentially
relevant
n=14
Included Studiesn=11
Studies rejected for
title
n=4
Studies Rejected for
abstract
n=5
Rejected full papers
n=2
Studies excluded
for quality
n=3