Studio manometrico dell'apparato sfinteriale anale in chirurgia proctologica prima e dopo blocco perineale posteriore

The aim of this study was to assess the physiological basis of the anal sphincter relaxation after posterior perineal block, using anal manometry. From January 1998 to December 2000 we performed a manometric study of anal sphincters during hemorrhoidectomy with regional anesthesia in our Department (Istituto di Chirurgia generale e toraco-polmonare, Ospedale Maggiore Policlinico, Milano). Twenty patients underwent anal manometry before 15 minutes after the posterior perineal block to determine the resting and the squeeze anal pressures. Statistical analysis was made using the Wilcoxon test. Differences were considered significant at p<0.05. We observed a mean reduction of about 40% of relaxation. Significant differences were observed between results before and post block (p<0.02). Our manometric study demonstrated that anal sphincter relaxation after posterior perineal block is correlated with the significant reduction of the resting and squeeze pressures after the regional anesthesia, because the block anesthetizes not only the somatic but also the sympathetic fibres. We confirm that posterior perineal block allows the surgeon to perform radical hemorrhoidectomy with optimal intraoperative and postoperative analgesia and safe relaxation.