Comparison of Outcomes and Time to Intervention in
Patients Undergoing CT Scan for Suspected Acute Abdomen
Process when Various Combinations of IV, Oral, and Rectal
Contrast Are Used
Authors:
Madeline S. Davis, MD1 and Alberto T. Diaz, PhD1,2
Program:
1GRMERC/MSU
Institutions:
2Spectrum
Corresponding
Author:
General Surgery Residency
Health
Madeline S. Davis, MD
GRMERC/MSU General Surgery Residency
1000 Monroe NW
Ph: 616-735-0449
Fax: 616-735-0449
Email: deimos@pho.bos
Current Version Date:
Previous IRB Approved Version Dates:
9/18/07
CONFIDENTIAL
This document is confidential and the property of Dr. Madeline Davis and Dr. Alberto Diaz. No
part of it may be transmitted, reproduced, published, or used by other persons without prior
written authorization from the authors.
Table of Contents
1
INTRODUCTION/SIGNIFICANCE ....................................................................................................... 3
2
STUDY OBJECTIVES ......................................................................................................................... 4
3
PATIENTS AND METHODS ................................................................................................................ 4
3.1
STUDY DESIGN .............................................................................................................................. 4
3.1.1 GENERAL DESIGN....................................................................................................................... 4
3.1.2 PRIMARY OUTCOME VARIABLE .................................................................................................... 4
3.1.3 SECONDARY OUTCOME VARIABLES ............................................................................................. 4
3.2
SUBJECT SELECTION AND W ITHDRAWAL ................................................................................... 5
3.2.1 INCLUSION CRITERIA................................................................................................................... 5
3.2.2 EXCLUSION CRITERIA ................................................................................................................. 5
3.3
STUDY PROCEDURES.................................................................................................................. 5
3.4
STATISTICAL PLAN ....................................................................................................................... 5
3.4.1
3.4.2
4
SAMPLE SIZE DETERMINATION .................................................................................................... 5
STATISTICAL METHODS ............................................................................................................... 5
DATA HANDLING AND RECORD KEEPING ..................................................................................... 5
4.1
4.2
4.3
CONFIDENTIALITY ........................................................................................................................... 5
RECORDS RETENTION .................................................................................................................... 6
REGULATORY BINDER ...................................................................................................................... 6
5
AUDITING AND INSPECTING ............................................................................................................ 6
6
BUDGET .............................................................................................................................................. 6
7
PUBLICATION PLAN .......................................................................................................................... 6
8
REFERENCES ..................................................................................................................................... 7
9
ATTACHMENTS .................................................................................................................................. 7
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1
Introduction
This study is to be conducted according to US and international standards of Good
Clinical Practice (FDA Title 21 part 312 and International Conference on Harmonization
guidelines), applicable government regulations and Institutional research policies and
procedures.
When evaluating a patient with an acute abdomen the optimal standard for performing
abdominal computed tomography (CT) is administration of oral, rectal and intravenous
(IV) contrast. However, administration of contrast through these three routes in an
urgent or emergent clinical setting may be limited due to patient care issues. The
majority of studies involving CT contrast for abdominal/pelvic evaluation have focused
on emergency room patients with a limited differential diagnosis. There are limited data
available on the ability to successfully interpret these examinations in other critically ill
patient populations given the absence of one or more of the contrast administrations.
Oral contrast allows small bowel opacification and aids in the diagnosis of structural
abnormalities such as ulcers, perforations, obstructions, and, in some cases, spaceoccupying lesions. Limitations for oral contrast use are patient intolerance due to ileus,
the need for intragastric administration via a tube, and time between administration and
CT study, which typically is 90 minutes.
Intravenous contrast is used to diagnose inflammatory-based lesions or for detection of
bowel wall pathology and provides detail regarding arterial supply and venous drainage
for abdominal organs. Situations that limit the use of IV contrast include allergy to iodine
or impaired renal function, the latter is a common clinical finding in urgent and emergent
clinical settings.
Rectal contrast, administered via enema, fills the colon from the rectum proximally,
possibly as far proximal as the ileocecal junction. This allows for visualization of spaceoccupying lesions, obstructions, diverticuli, anastomotic leaks, bowel perforation, and
inflammatory bowel diseases affecting the large intestine. Limitations mainly involve
limited access to the anorectum or concern regarding contrast extravasation.
Multiple studies have been performed comparing various combinations of contrast in
specific disease states involving the abdomen. However, they are limited to the
emergency department setting. The goal of these studies was to determine the most
effective use of contrast. Huyn et al. found they could shorten time to diagnosis an
average of 68 minutes by performing CT without contrast for acute abdomen compared
to contrast-enhanced CT.1 One study suggests there is a 79% agreement between noncontrast enhanced and contrast enhanced CT for abdominal pelvic pain, attributing the
discrepancy largely to interobserver variability.2 In a study comparing unenhanced CT to
three-view acute abdominal series, MacKersie et al. reported no change in any
diagnosis among a small group of patients that underwent follow-up contrast-enhanced
CT after initial unenhanced CT.3
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When comparing IV contrast to unenhanced CT for acute abdominal pain, particularly
diverticulitis and appendicitis, there was no significant difference between diagnostic
outcomes.4,5 This was mainly attributed to the visible pericecal and periappendiceal fat
inflammatory changes that aided the diagnosis in unenhanced CT.4 However, Jacobs et
al. concluded that the use of IV contrast significantly improved the radiologists' ability to
diagnose acute appendicitis or to establish an alternative diagnosis.6
There is limited data involving the evaluation of patients with a broader range of
potential diagnostic entities that may include vascular disease, intrinsic bowel disease,
and/or intraabdominal processes. This is particularly true for patients in the intensive
care setting, where clinical presentation can be very difficult to assess.
We propose to study the pattern of use and outcomes of CT imaging when various
combinations of contrast are used for diagnostic purposes in a broad range of hospital
inpatients with suspicion of an acute abdominal process.
2 Study Objectives
Primary Objective: The primary objective will be to determine which contrast
combination provides the most accurate diagnosis.
Secondary Objective: The secondary objective will be to determine which contrast
combination provides the shortest time to definitive intervention after CT completion.
3 Patients and Methods
3.1 Study Design
3.1.1 General Design
This protocol will use a retrospective cohort design. Of all hospital inpatients
undergoing an urgent or emergent abdominal/pelvic CT with any combination of
contrast, intravenous, oral, or rectal, for a suspected acute abdominal process.
3.1.2 Primary Outcome Variable
The primary outcome variable will be the accuracy of diagnosis.
3.1.3 Secondary Outcome Variables
The secondary outcome variable will be the time to definitive intervention after CT
completion.
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3.2 Subject Selection and Withdrawal
3.2.1 Inclusion Criteria
All adult (age > 18) patients from the Spectrum Health ICU or Emergency
Department undergoing an urgent or emergent abdominal/pelvic CT with any
combination of contrast, intravenous, oral, or rectal, for a suspected acute
abdominal process.
3.2.2 Exclusion Criteria
Patients with appendicitis.
3.3 Study Procedures
Charts from patients who fit the inclusion and exclusion criteria, from the Spectrum
Health ICU or Emergency Department, from June 1, 2006, through May 31, 2007,
will be reviewed. CT reports and procedure or operative notes will be reviewed to
define accuracy of diagnosis and time and type of definitive treatment. Variables to
be recorded include age, sex, ordering department, contrast agents used, time to
intervention, correct CT diagnosis, and intervention type.
3.4 Statistical Plan
3.4.1 Sample Size Determination
As this study is of an exploratory nature, no formal sample size analysis has been
run.
3.4.2 Statistical Methods
Quantitative data will be expressed as the mean+SEM, while nominal data will be
expressed as a percentage. The average time to intervention between the
contrast combinations will be compared using the one-way analysis of variance.
Correct diagnosis from CT and the intervention type, being nominal data, will be
compared with a 2 test. Significance will be assessed at p < 0.05.
4 Data Handling and Record Keeping
4.1 Confidentiality
Information about study subjects will be kept confidential and managed according to
the requirements of the Health Insurance Portability and Accountability Act of 1996
(HIPAA). Those regulations require that the Spectrum Health Privacy Board grant
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approval of an authorization to collect the Protected Health Information (PHI) without
written consent from the participant for research purposes.
4.2 Records Retention
The correlation tool will be destroyed at the completion of the study in accordance
with the Spectrum Health documentation destruction policy.
4.3 Regulatory Binder
A regulatory binder will be maintained for this study. This will include items such as
this protocol, the letter of approval from the IRB, the Waiver of Authorization form,
and all other information pertinent to this study.
5 Study Auditing and Inspecting
The investigator will permit study-related monitoring, audits, and inspections by the
Spectrum Health IRB, the sponsor, government regulatory bodies, and Spectrum
Health research compliance and quality assurance groups of all study related
documents (e.g. source documents, regulatory documents, data collection
instruments, study data etc.).
Participation as an investigator in this study implies acceptance of potential
inspection by government regulatory authorities and applicable Spectrum Health
compliance and quality assurance offices.
6 Budget
No funds are required for this project. Dr. Davis will obtain the data from the
charts, and the GRMERC Research Department will analyze the data.
7 Publication Plan
Findings will be shared and discussed with all of the investigators for the study. An
estimated timeline for creation of an abstract will be defined at that time. An
abstract of the completed study, after input from all of the authors, will be submitted
to the Midwest Surgical Association or their meeting on August 25-28, 2008. A
manuscript of the study, having received input from all of the authors, is tentatively
scheduled for submission on August 1, 2008.
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8 References
1. Huyn LN, Coughlin B, Wolfe JM, Blank FS, Lee SY, Smithline HA. Patient encounter
time intervals in the evaluation of emergency department patients requiring
abdominopelvic CT: oral contrast versus no contrast. Emerg Radiol. 2004;10:310-3.
2. Lee SY, Coughlin B, Wolfe JM, Polino J, Blank FS, Smithline HA. Prospective
comparison of helical CT of the abdomen and pelvis without and with oral contrast in
assessing acute abdominal pain in adult emergency department patients. Emerg
Radiol. 2006;12:150-7.
3. MacKersie AB, Lane MJ, Gerhardt RT, Claypool HA, Keenan S, Katz DS, Tucker JE.
Nontraumatic acute abdominal pain: unenhanced helical CT compared with threeview acute abdominal series. Radiology. 2005;237:114-22
4. Mun S, Ernst RD, Chen K, Oto A, Shah S, Mileski WJ. Rapid CT diagnosis of acute
appendicitis with IV contrast material. Emerg Radiol. 2006;12:99-102.
5. Basak S, Nazarian LN, Wechsler RJ, Parker L, Williams BD, Lev-Toaff AS, Kurtz
AB. Is unenhanced CT sufficient for evaluation of acute abdominal pain? Clin
Imaging. 2002;26:405-7.
6. Jacobs JE, Birnbaum BA, Macari M, et al. Acute appendicitis: comparison of helical
CT diagnosis-focused technique with oral contrast material versus nonfocused
technique with oral and intravenous contrast material. Radiology 2001;220:683-90.
9 Attachments
These include the waiver of authorization, application checklist, and study datasheet.
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