Anal pressure vectography is of no apparent benefit for sphincter evaluation

Anal pressure vectography is an attractive study which can provide colorful 3-dimensional video images to assess radial asymmetry. However, the value of this test is still uncertain. The aim of this study was to assess prospectively the correlation among APV and other anorectal physiological tests, such as anal manometry, anal sphincter electromyography (EMG), and anal ultrasonography. Fifty consecutive patients with faecal incontinence were evaluated. All 50 patients had APV and anal manometry during the same visit. APV revealed mean maximal resting and mean maximal squeeze pressures of 83.1 +/- 28.4 mmHg and 106.3 +/- 34.5 mmHg, respectively. Anal manometry showed mean maximal resting and mean maximal squeeze pressures of 55.9 +/- 19.4 mmHg and 57.7 +/- 29.4 mmHg, respectively. The difference between APV and manometry for both mean maximal resting and mean maximal squeeze pressures were significant (P < 0.05). Thirty-four of the 50 patients (68%) showed global defects of the sphincters on cross-sectional vectogram. Forty-six patients also had anal sphincter mapping with electromyography; 38 patients had isolated decreased EMG activity in a single quadrant. However, only five of the 38 patients (13.2%) had the same defect localized by APV. Lastly, 33 patients had anal ultrasonography; 27 patients had anal sphincter defects. However, only 3 of the 27 patients (11.1%) had the same defects localized by APV. In conclusion, APV had poor correlation with other anorectal physiological tests, including anal manometry, anal sphincter EMG, and anal ultrasonography. Therefore, APV has no apparent advantages, so its use cannot be supported.