The Effect of Patient Oral Intake Status on Abdominal Aortic Ultrasound Visualization

The standard abdominal aortic duplex ultrasound protocol requires fasting for 8-12 hours prior to examination in attempt to reduce bowel gas and improve visualization. Such practice results in frequent testing delays and patient non-compliance. The aim of this study was to determine whether fasting improves visualization of the abdominal aorta in patients undergoing duplex ultrasound or influences diagnostic properties.

This was a prospective, randomized, double-blind imaging trail at a single institution. Ninety patients were randomized to one of three dietary groups, including NPO, clear liquids or control (regular diet). Diagnostic ultrasound examinations were performed by accredited Registered Vascular Technologists who remained blinded to the patients' diet. Sonographers commented on the presence of limited visualization in the study based on their ability to accurately measure aortic diameter. Examination results were randomly assigned to interpreting physicians who were also blinded to the patients' diet. Following interpretation, the reading physician was asked to comment whether they had sufficient information for a conclusive diagnostic interpretation.

All ultrasound studies were deemed diagnostic by the interpreting physician regardless of the patients' dietary status. Limited visualization was reported in 19 of the 90 study patients (21.1%) with no significant difference existing between the dietary groups (P = 0.344). The NPO group contained the most patients with studies deemed to have limited visualization.

Oral intake status did not affect visualization of the abdominal aorta or the rate of diagnostic studies in patients undergoing DUS at a single center. These results suggest that dietary restrictions prior to DUS evaluation of the abdominal aorta is unnecessary.