PURPOSE:Hemorrhoidectomy is considered to be a painful operation, therefore some patients with symptomatic hemorrhoids conceal their symptoms to defer a much-needed surgical procedure. Patients who have undergone hemorrhoidectomy have experienced constipation or urinary retention due to postoperative pain. Several interventions have been used to relieve postoperative pain after hemorrhoidectomy. Nevertheless, the results are unsatisfactory. Hemorrhoidectomy with ultrasonic dissector have less thermal injury and can avoid ligation and suture. This study compared conventional semi-open Milligan hemorrhoidectomy with open ultrasonic dissector hemorrhoidectomy. METHODS:One hundred patients with prolapsed symptomatic hemorrhoids were randomly assigned to semi-open Milligan (n=50) or open ultrasonic dissector (n=50) hemorrhoidectomy. Operation time, postoperative complication, hospital stay, degree and duration of postoperative pain, pain on bowel movement, and urinary retention were recorded and analyzed. RESULTS:There was no significant difference in excised pile number. Operation time of open ultrasonic dissector hemorrhoidectomy was shorter than that of semi-open Milligan hemorrhoidectomy (P<0.05). The open ultrasonic dissector hemorrhoidectomy group resulted in less postoperative pain (P<0.05) and shorter duration of pain (P<0.05) and postoperative hospital stay (P<0.05) than semi-open Milligan hemorrhoidectomy. Urinary retention did not occur in both groups. CONCLUSIONS:Despite the higher cost, open ultrasonic dissector hemorrhoidectomy results in less postoperative pain, shorter operation time and hospital stay than the conventional hemorrhoidectomy.