Rectal Gas Volume Measured by Computerized Tomography Identifies Evacuation Disorders in Patients With Constipation  Seon-Young Park, Disha Khemani, Alfred D. Nelson, Deborah Eckert, Michael Camilleri  Clinical Gastroenterology and Hepatology  Volume 15, Issue 4, Pages 543-552.e4 (April 2017) DOI: 10.1016/j.cgh.2016.11.013 Copyright © 2017 AGA Institute Terms and Conditions

Figure 1 (A) Images from a 28-year-old woman with rectal evacuation disorder as shown by the retained isotope in the left colon at 24 hours (lower middle panel) and in the rectum at 48 hours (lower right panel), as well as the gas in the rectum in the abdominal scout film (upper left panel), and coronal (upper right panel) and transaxial (lower left panel) images. (B) Images from a 52-year-old woman with evacuation disorder showing trapped gas in the rectum shown by the abdominal scout film (left panel) and cross-sectional image on CT (right panel). The measured rectal gas volume and maximum rectal gas area were 12.7 cm3 and 28.6 cm2, respectively. (C) Examples of rectal gas visualization in a patient without a rectal evacuation disorder. Images show the abdominal scout film (left panel) and cross-sectional image on CT (right panel) from a 34-year-old woman with slow-transit constipation. The rectal gas volume of 2.51 cm3 and maximum rectal gas area of 1.5 cm2 were considerably lower in this patient than in the patient with a rectal evacuation disorder shown in panel B. Clinical Gastroenterology and Hepatology 2017 15, 543-552.e4DOI: (10.1016/j.cgh.2016.11.013) Copyright © 2017 AGA Institute Terms and Conditions

Figure 2 Rectal gas volume (median, interquartile range), maximal rectal gas area, and rectal gas area on abdominal scout film in patients with rectal evacuation disorders, normal-transit constipation, and slow-transit constipation. There were significant differences in (A) rectal gas volume, (B) rectal gas maximum area on CT, and (C) rectal gas area on abdominal scout film among the 3 groups (P < .001, P < .001, and P = .033, respectively). ANOVA, analysis of variance; AP, anteroposterior. Clinical Gastroenterology and Hepatology 2017 15, 543-552.e4DOI: (10.1016/j.cgh.2016.11.013) Copyright © 2017 AGA Institute Terms and Conditions

Figure 3 (A) Spearman correlation between total rectal gas volume and rectal gas maximum area, both measured on transaxial CT (Spearman correlation coefficient, Rs = 0.977; P < .001). (B) Spearman correlation between rectal gas area on abdominal scout film and rectal gas volume (Rs = 0.703; P < .001) (right panel) and rectal gas maximum area (Rs = 0.695; P < .001) (left panel) on transaxial CT. Clinical Gastroenterology and Hepatology 2017 15, 543-552.e4DOI: (10.1016/j.cgh.2016.11.013) Copyright © 2017 AGA Institute Terms and Conditions

Figure 4 Spearman correlation between total rectal gas volume and weight added to the balloon expulsion test (Spearman correlation coefficient, Rs = 0.345; P < .001). Clinical Gastroenterology and Hepatology 2017 15, 543-552.e4DOI: (10.1016/j.cgh.2016.11.013) Copyright © 2017 AGA Institute Terms and Conditions

Supplementary Figure 1 Flow chart of the patient cohort, starting with 1553 medical records. Eventually, 63 patients with evacuation disorders, 17 patients with slow-transit constipation, and 38 patients with normal-transit constipation were enrolled in this study. Clinical Gastroenterology and Hepatology 2017 15, 543-552.e4DOI: (10.1016/j.cgh.2016.11.013) Copyright © 2017 AGA Institute Terms and Conditions