ª Springer Science+Business Media New York 2016

Abdominal Radiology

Abdom Radiol (2016) DOI: 10.1007/s00261-016-0969-3

Oral contrast administration for abdominal and pelvic CT scan in emergency setting: is there a happy medium? Farnoosh Sokhandon Department of Radiology, Beaumont Health, Oakland University William Beaumont SoM, 115-IC, 3601 West 13 Mile Rd, Royal Oak, MI 48073, USA

‘‘Action expresses priorities.’’ Mahatma Gandhi In the past several years, Emergency departments across the nation have been facing challenges with their patients’ length of stay. Our institution was no exception. Approximately seven years ago, we were asked to look into our oral contrast administration policy for abdominal and pelvic CT scans performed in the emergency department (ED). Length of stay (LOS) is considered one of the important indicators of quality of care in Emergency departments in the US [1]. Emergency departments are under scrutiny for long ED stays. Many factors have been recognized in association with longer ED stays. One that has received special attention among abdominal imagers is the administration of oral contrast to ED patients in need of abdominal/pelvic CT scan. While the mean duration of an ED visit is reported slightly more than 3 h [2], the extra 1–2 h of wait time for oral preparation seems quite significant. As in many other institutions, we were asked to consider eliminating the use of oral contrast in ED. The request at the time was supported by a growing body of studies both in Emergency Medicine and Radiology literature. For example, in a prospective study of 100 ED patients with abdominal pain, where the patients were scanned without and then with oral contrast, Lee et al. [3] found only 2 cases out of 100 with discrepant findings. A meta-analysis of 23 studies showed a similar sensitivity (95% vs. 92%), specificity (97% vs. 89%), and accuracy (97% vs. 89%) in the diagnosis of appendicitis with and without oral contrast, respectively. Other researchers studied patients with suspected appendicitis and showed no hindered diagnostic confidence in the absence of oral contrast [4].

Correspondence to: Farnoosh Sokhandon; email: [email protected]

At the time, it seemed convincing that oral contrast may not be necessary for the majority of adult abdominal and pelvic CT scans performed in the ED, and the result of our literature search was promising. During a short period trial at our main campus in Royal Oak, Michigan, one of the eight Beaumont Health System hospitals, we eliminated the use of oral contrast in adult ED patients. We carefully reviewed the cases, monitored the radiology reports, followed up with the radiologists reading those cases, and kept the line of communication with ED physicians and our radiology colleagues open. In the short trial period, the rate of repeat abdominal CT scans began to rise. Disclaimers such as ‘‘evaluation of bowel is limited due to lack of oral contrast’’ were appearing in radiology reports, thus warranting repeat examinations, specifically in a subgroup of patients who remained symptomatic or would present with recurrent symptoms shortly after being discharged from ED. Soon we came to the conclusion that eliminating oral contrast in ED adult abdominal and pelvic CT scans would be a drastic change, and if extrapolated to all our centers, with a group of more than one hundred radiologists with different levels of expertise and opinion, accustomed to looking at opacified bowel for their entire career and who are committed to offering the best quality exams possible, the change would not be received well. We needed to prioritize, and find a rule to help with choosing the right patients for elimination of oral contrast. In reviewing the abdominal and pelvic CT scans that were done without oral contrast, we realized the majority of cases in whom a repeat CT scan with oral contrast was performed belonged to patients with lower BMI. Most radiologists seemed to be comfortable with the no oral contrast abdominal/pelvic CT scan concept, if there was adequate intraperitoneal fat to separate the bowel loops. Developing a protocol with a BMI cutoff for use of oral contrast in ED patients seemed to be the logical answer.

F. Sokhandon: Oral contrast administration for abdominal and pelvic CT scan

The ED length of stay would decrease, while increasing the overall number of abdominal CT scans with an acceptable diagnostic quality. The new question was: What should be the BMI cutoff for use of oral contrast? As per Centers for Disease Control and Prevention (CDC) definition, for adults age 20 and older, BMI of 25–29.9 is considered overweight, BMI of 30–39.9 is considered obese, and a BMI greater than 40 is considered extremely obese [5]. Utilizing this classification, back in 2007, our department established a comprehensive program to reduce the radiation dose related to CT imaging, during which a set of BMI criteria was developed with a cutoff of 30, for changing scan parameters to reduce radiation while maintaining quality [6]. The BMI limit of 30 worked quite well with radiation dose reduction; therefore, we decided to start with this threshold. Patients in whom BMI was greater than 30 would have their abdominal and pelvic CT scan done without administration of oral contrast, and patients with BMI of less than 30 would require oral contrast. In the absence of oral contrast, abdominal imagers commonly face the challenge of differentiating acute female pelvic organ abnormalities such as tubo-ovarian abscess, hydro- or pyosalpinx, and ovarian torsion from bowel-related pathologies, such as perforated appendix, colonic, or small bowel diverticulitis. In male patients, however, such differentiation is not an issue. Therefore, it seemed reasonable, at least to try a lower BMI as cutoff for administration of oral contrast in male patients. Moreover, gender differences in distribution of abdominal fat would be in favor of lower BMI cutoff in male patients. In general, women deposit fat mostly around their pelvis, buttocks, and thighs, and less within the abdomen; whereas men deposit fat mostly in their peritoneal cavity. A trial protocol was proposed, and accepted by the ED physicians and our colleagues in radiology, to avoid administration of oral contrast to the male patients with BMI above 25, and to the female patients with BMI above 30, who needed abdominal and pelvic CT scan. Following a 1-month trial, CT scan images were reviewed for diagnostic quality, radiology reports were screened for limitations due to lack of oral contrast, and the rate of repeat examination was also evaluated. Radiologists seemed to be comfortable with this new protocol, and ED physicians were satisfied with reduction of their patients’ length of stay. Although with the above protocol we still administer oral contrast to some ED patients, the majority of adult patients are scanned without oral contrast due to a number of factors such as clinical indication, our specific adult patient population, and type of exam. For example, a few CT examinations per our departments’ protocol do not require oral contrast, such as renal stone studies, abdominal CT angiograms, and acute trauma patients. Others follow the BMI criteria. According to the National Health and Nutrition Examination Survey (NHANES), 74% of adult men, older

than 20 years of age in the United States, have BMI of greater than 25, and 38.3% of women have BMI greater than 30 [7]. Although unfortunate, these data are in favor of using the BMI protocol. Based on these data, the majority of our adult patients, specifically men, fall in the category in which we would not administer oral contrast. In other words, if these data are extrapolated to our patient population, since the BMI threshold for men is set so low, we are perhaps administering oral contrast to less than 26% of our ED adult male patients, the group that has a BMI of less than 25 and the clinical indication/exam-type calls for oral contrast administration. The number of women receiving oral contrast however is higher. Approximately 61.7% of women have BMI of less than 30 and thus will require oral contrast; however, this seems to be an acceptable tradeoff for an improved chance of acquiring a satisfactory diagnostic examination in the first attempt. Utilizing a BMI threshold of 25 for adult men, and 30 for adult women, to administer oral contrast for abdominal and pelvic CT scan in ED patients appears to be a reasonable solution to facilitate shorter ED stays, while maintaining the diagnostic quality of CT scans, and reducing the need for repeat examination. While ED time constraints have certainly modified our current practice, taking action based on priorities has provided a reasonable approach based on demographics of our patient population. Compliance with ethical standards Funding No funding was received for this study. Conflicts of interest The authors declare that they have no conflict of interest. Ethical approval This article does not contain any studies with human participants or animals performed by any of the authors. Informed consent Statement of informed consent was not applicable since the manuscript does not contain any patient data.

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