Aim: To assess the efficiency of the micro-flavonoid fraction (MMF) administration prior to anorectal surgery with spinal anesthesia on postoperative pain severity reduction.

Methods: Patients who meet the following criteria are included: participants must be diagnosed with surgical treatment of anorectal diseases. All participants are randomly divided into 2 groups: the first one gets a tablet with 1000 mg MFF (Detralex®), the second one gets a tablet containing starch per os 14 days before surgery (72 participants per arm). Then patients of each group will continue MFF administration for 30 days after surgery. Patients of both arms receive spinal anesthesia and undergo surgery. Following the procedure the primary and secondary outcomes are evaluated: frequency of the opioid drugs intake, the severity of the postoperative pain syndrome, duration and frequency of other drugs intake, readmission rate, overall quality of life, time from the procedure to returning to work and the complications rate, C-reactive protein level.

Discussion: the MFF intake allows reducing the severity of the hemorrhoidal disease symptoms during conservative treatment. In addition, the Detralex® efficacy has been proven in postoperative pain reduction for patients diagnosed with varicose veins of the lower extremities. The investigators intend to evaluate the feasibility of the preoperative MFF administration for the postoperative pain reduction and the decrease of the postoperative complications in patients with hemorrhoidal disease.

Inclusion Criteria:

• Stage 2-4 hemorrhoidal disease;
• Presence of indications for elective surgery (open hemorrhoidectomy) using mono or bipolar coagulation possibly combined with other minimally invasive methods: hemorrhoidopexy and mucopexy, Ligasure hemorrhoidectomy;
• Absence of other diseases that cause pain;
• Class I, II ASA anesthesia risk;

Exclusion Criteria:

• The presence of the following diseases: paraproctitis, inflammatory bowel disease, metabolic or endocrine disorders, alcoholism, drug use, blood clotting disorders, and history of diseases in the anorectal region;
• Contraindicated or technically impossible subarachnoid anesthesia;
• Patients who refused to participate;
• Pregnant women.