Assessing the Presence and Severity of Constipation with Plain Radiographs in Constipated Palliative Care Patients

Background: Palliative care guidelines recommend plain radiographs to assess constipation based on the presumption that visible fecal shadowing represents stool retention. Despite this, using plain radiographs in this way is not well validated. Objectives: This work's main aim was to compare clinicians' reports of fecal loading on radiographs. This study also compares clinicians' assessments with radio-opaque marker transit studies and patients' self-reported constipation symptoms. Methods: This study was conducted in a sample of 30 constipated palliative care patients taking laxatives who had all undergone colon transit studies and contemporaneous assessment of constipation symptoms with the Patient Assessment of Constipation Symptom (PAC-SYM) questionnaire. Four separate clinicians independently reported their opinions of fecal loading using a previously developed fecal loading scale. Participant details were summarized and pair-wise inter-rater agreement among all four raters were examined using the Bland-Altman approach. For the comparisons of the clinician-assigned fecal loading score between the radiographic assessment of the normal and slow colon transit time, the nonparametric approach of Mann-Whitney U tests were applied. Spearman's correlation analyses were employed to investigate the association between the clinician-assigned fecal loading score and the patient self-reported PAC-SYM score. Results: The results of this study are very similar to other studies conducted in functional constipation, highlighting systematic disagreement between observers. Further poor correlations were noted between fecal loading scores and colon transit times and with patient self-reported symptoms. Conclusion: These results, when considered with other work in chronic constipation, question the ongoing use of radiographs in the diagnosis of constipation.