A new method of assessing anal sphincter integrity using inverted vectormanometry.
OBJECTIVE
Vectorgraphy as an integrated mapping of radial pressure profiles of the anal canal has been used to attempt identification of pressure-related defects with doubtful reliability since vectorgraphs bear no resemblance to endoanal ultrasound scans at similar levels in the anal canal. This study aimed to devise a technique to enable vectorgraphy to be more representative of sphincter function and integrity.


METHODS
Vectormanometry was performed in 50 patients with anorectal disorders using an Arndorfer pneumohydraulic system. "Normal" three-dimensional manometric images of each 0.5 cm of the anal sphincter were computer-generated by plotting anal pressures at rest and during squeeze radially around a central zero axis. The graphs were replotted with zero at the periphery and maximal anal pressure at the center. Both this ("inverted") and "normal" vectorgraphs were compared with endoanal ultrasound images at similar levels, assessing both internal and external anal sphincters.


RESULTS
Standard vectormanometry produced excellent pictures of pressures throughout the anal canal; the anatomy however bore no resemblance to the pictures produced by endoanal ultrasound. The inverted vectographs showed a much better correlation with endoanal ultrasound at each 0.5-mm level of the anal canal, for both squeeze pressure graphs and external sphincter correlations and for resting pressure graphs and internal sphincter correlations.


CONCLUSIONS
Accurate assessment of sphincter integrity is not possible when interpreting the vectormanometry graphs in the current format; however, inverted vectorgraphy gives good correlations with endoanal ultrasound and provides combined functional (pressure measurement) and anatomic (three-dimensional profile) information regarding the anal canal.
Kaur
Geetinder
G
Academic Surgical Unit, University of Hull Postgraduate Medical School, Castle Hill Hospital, Cottingham, United Kingdom.
Gardiner
Angela
A
Duthie
Graeme S
GS
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001003:Anal Canal / Q000000981:diagnostic imaging / Q000503:physiopathology*; D001004:Anus Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003248:Constipation / Q000503:physiopathology; D005242:Fecal Incontinence / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008365:Manometry / Q000379:methods*; D008875:Middle Aged; D009119:Muscle Contraction; D011312:Pressure; D014463:Ultrasonography