Use of Oral Contrast in Abdominal/Pelvic CT Scans.

The COVID-19 pandemic has disrupted activities throughout society, including workflow in radiology departments. Imaging initially had to be halted, then carefully triaged, and is now being reinstated with modifications for a ‘‘new normal’’ in Canada. Despite these challenges, this situation does provide an opportunity to reevaluate our long-held practices, particularly when considering patient safety and patient experience. Specifically, in abdominal imaging, there is a strong impetus for reducing the use of oral contrast for computed tomography (CT) scans. In many institutions, the administration of positive oral contrast has become the default way of performing a CT scan of the abdomen and pelvis. However, a growing body of literature has questioned the status quo. Literature has shown that the diagnosis of appendicitis as well as nontraumatic abdominopelvic symptoms does not require oral or rectal contrast. Even in thin patients with a body mass index of <25, a study by Ramalingam et al demonstrated that CT scan without oral contrast had similar accuracy to CT scans performed with oral contrast. In a time when COVID-19 is leading us to increase social distancing and there is pressure to reduce patient time in the radiology waiting room, this should encourage radiologists to reevaluate the use of oral contrast in CT. Oral contrast administration usually begins 1 to 2 hours prior to the scan and therefore increases the time needed to perform a CT. This can negatively affect the throughput of patients in the emergency department (ED), which is of importance especially in Canada, as many EDs already have long wait times. In addition to delays, the ingestion of fluid goes against the dictum of ‘‘nil per oral,’’ which is usually required for a patient planned for surgery. Patients who are acutely ill may not be able to ingest large volumes of fluid by mouth, and forcing them to do this would further distress them. In patients with high-grade bowel obstruction, further administration of 1000 mL of fluid can result in vomiting, which can lead to aspiration, particularly in older patients, resulting in increased morbidity and mortality. Reducing routine use of oral contrast is also very important in the case of patients coming to the hospital as outpatients, especially from oncology to evaluate the state of their cancer. Many of these patients are immunocompromised and at higher risk for complications if they contract COVID-19. The Hippocratic oath ‘‘First, do no harm’’ should strongly make us reconsider the use of oral contrast, especially in situations where there is no evidence that it makes a difference to our diagnostic accuracy. Although it may be ‘‘easier’’ for a radiologist to report a study with oral contrast because they are used to it, it does not mean that this is the best for the patient. Also, in a time when there is a significant need for fiscal responsibility, reduction in the unnecessary use of oral contrast should be implemented in all radiology departments. Although each glass of oral contrast is not expensive, due to a large number of patients scanned every year at large institutions, the cost does add up. So, what can we do to change the status quo? Do we have better solutions? As discussed earlier, in patients presenting to the ED with abdominal pain or suspected appendicitis, only administering intravenous contrast will suffice. The use of oral contrast should be reserved for assessing anastomotic leaks in patients who have recently undergone bowel surgery and in specific cases for problem-solving. Some cancers are associated with higher risks of peritoneal seeding and use, or oral contrast may help differentiate a bowel loop from a peritoneal metastasis. Oral contrast administration may also be helpful in patients with underlying malignancy, who cannot have intravenous contrast, due to severe allergy or poor kidney function, as the oral contrast does help increase contrast resolution of the unenhanced CT scan. However, the vast majority of patients with cancer do not require routine use of oral contrast. By educating clinicians to provide a complete history and proactive patient-centered protocolling of CT scans by radiologists, oral contrast usage can be significantly reduced. In very specific situations, the relationship between oral contrast administration and patient outcomes is closely linked. Management of recurrent small bowel obstructions due to adhesions is primarily conservative. Patients with incomplete obstruction are usually treated with bowel rest, often including nasogastric decompression, for 3 to 5 days. A ‘‘Gastrografin challenge test’’ (diatrizoate meglumine) has been proposed as a