Objective: The objective of this review is to determine the diagnostic accuracy of positive oral contrast versus no oral contrast for common, non-traumatic computed tomography abdominal indications in adults. Introduction: Positive oral contrast is regularly administered to patients to drink prior to computed tomography scans of the abdomen and pelvis. The purpose of the preparation is to improve visualization of the bowel, however, technological advances in scanner design may mean positive oral contrast is no longer required. Inclusion criteria: Eligible studies will consider the use of positive oral contrast in non-traumatic indications for computed tomography of the abdomen and pelvis to include appendicitis, bowel obstruction, diverticulitis, intestinal neoplasms and metastasis (screening or staging), or acute abdomen. The review will use the discharge diagnosis as the reference standard. Studies that describe adult patients (18+) and published from 2000 on will be considered. Methods: MEDLINE Complete, Embase, CINAHL, and Scopus will be searched, along with Google Scholar and numerous radiology college websites. Screening of potential titles and abstracts, retrieval of full-text studies, assessment of methodological quality, and data extraction will be performed independently by two reviewers. Meta-analyses will be performed, if possible, and a Grading of Recommendations, Assessment, Development and Evaluation Summary of Findings presented. Systematic review registration number: PROSPERO (CRD42020184285)