US of the upper abdomen: factors influencing image quality.

A controlled blind study of 226 patients was performed to determine the advantages of fasting prior to upper abdominal ultrasonography (US) as well as the influence of other factors on image quality. The ratio of weight to height (a reflection of body build) was found to most often correlate negatively with image quality for all organs, followed by age for the biliary tract, pancreas, and kidneys and sex (in males) for the pancreas. Only the biliary tract was shown slightly better as the result of fasting. Images obtained during the afternoon tended to be somewhat better. The authors conclude that upper abdominal US can be performed at any time in patients who have not fasted, as it is primarily other factors that determine image quality. Only if evaluation of the biliary tract is inconclusive need the patient be reexamined after fasting.