The anorectal angle is not a reliable parameter on defaecating proctography.

Proctography is a standard method of investigating anorectal disorders. The parameters derived from this X-ray include the anorectal angle. The reproducibility of this measurement was assessed in 43 defaecating proctograms viewed by four observers on two separate occasions. Measurements were made at rest and during defaecation straining. Significant intra- and inter-observer variation was found. The anorectal angle is an inaccurate measurement, and should be interpreted with caution.