Systematic review with meta-analysis: defecography should be a first-line diagnostic modality in patients with refractory constipation.

Pathological structural abnormalities, as well as functional abnormalities, are common in patients with chronic constipation. Since structural abnormalities cannot be evaluated using nonimaging test modalities (balloon expulsion and anorectal manometry), defecography should be considered the first-line diagnostic test if resources allow.