| Abstract: | ![]()
The purpose of this study was to usesimultaneous anal manometry and high-frequencyendoluminal ultrasonography (EUS) to determine therelationship between resting anal pressure andcross-sectional area of the internal and external anal sphincters.Eleven normal subjects underwent simultaneous anal EUSand manometry using catheters containing both pressureports and ultrasound transducers. Resting pressure and cross-sectional area of the sphincters weremade throughout the anal sphincter complex. The lengthof the internal anal sphincter (IAS) by sonography (27± 5 mm) was significantly less than the length of the high pressure zone (HPZ) by manometry(44 ± 8 mm; P < 0.001). Maximum IAScross-sectional area (CSA) occurred 10 ± 6 mmproximal to the peak resting pressure. The resting analpressure correlated with external anal sphincter (EAS) CSA (r =0.77), but not with IAS CSA (r = –0.17). The sumof EAS CSA and IAS CSA correlated strongly with restingpressure (r = 0.85). In conclusion, the IAS is shorter than the HPZ, with a significant distanceseparating maximum IAS CSA from peak resting pressure.The sum of the IAS and EAS CSAs, but not that of the IASalone, correlated with resting pressure. Thus, this study suggests that the EAS, in addition to theIAS, contributes to resting anal pressure. |
