Determination of Normal Distribution of Distended Colon Volumes to Guide Performance of Colonic Imaging With Fluid Distention

The purpose was to determine the normal distribution of distended colon volumes as a guide for rectal contrast material administration protocols. All computed tomography colonography studies performed at Emory University Hospital, Atlanta, Georgia, between January 2009 and January 2015, were reviewed retrospectively. In total, 85 subjects were included in the analysis (64% [54 of 85] female and 36% [31 of 85] male). Mean patient age was 65 years (range: 42-86 y). Distended colon volumes were determined from colon length and transaxial diameter measurements made using a 3-dimensional workstation. Age, sex, race, height, weight, and body mass index were recorded. The normal distributions of distended colon volumes and lengths were determined. Correlations between colonic volume and colonic length, and demographic variables were assessed. Mean colon volume was 2.1 L (range: 0.7-4.4 L). Nearly, 17% of patients had a distended colonic volume of >3 L. Mean colon length was 197 cm (range: 118-285 cm). A weak negative correlation was found between age and colonic volume (r = −0.221; P = 0.04). A weak positive correlation was found between body mass index and colonic length (r = 0.368; P = 0.007). Otherwise, no significant correlations were found for distended colonic volume or length and demographic variables. In conclusion, an average of approximately 2 L of contrast material may be necessary to achieve full colonic opacification. This volume is larger than previously reported volumes (0.8-1.5 L) for rectal contrast material administration protocols.