The participants were hospitalized in Orthopedic and Traumatology Departments in Military Institute of Medicine, Warsaw, Poland.

The inclusion criteria were (1) age to 40 year-old, (2) no history of urologic problems, and (3) surgery under spinal anesthesia. All the patients where (1) opioids were administered during the surgery, (2) general anesthesia was necessary, and (3) the urinary bladder catheterization was perform during the surgery were excluded from the study.

The participants were randomly divided into the study and control groups. No oral premedication was administered. All the patients were asked to empty their urinary bladders before arrival to the operating theatre. When the standard monitoring (continuous electrocardiogram, noninvasive blood pressure, pulse oximetry) was started, intravenous premedication with midazolam was administered and lumbar spinal anesthesia with hyperbaric 0.5% solution of bupivacaine hydrochloride was performed.

In the study group, but not in the the control one, the 40 mg of drotaverine hydrochloride was administered intramuscularly. The decresed intravascular volume was corrected with cristalloids. During the surgery the adequate, not deeper than II grade according to Ramsay scale, level of sedationt was obtained with midazolam and/or propofol. All the participants received a questionaire in which we asked the questions about (1) the duration of anesthesia, (2) the time of micturition, (3) the time when discomfort or pain appeared in the lower abdomen, (4) the incidence of the urinary bladder catheterization and time to catheterization. On the next day after the surgery the questionaires were collected. In cases, when the patient's dischaged from the hospital was planned during the weekend, he or she was asked to pass on the questionaire to the nurses.

Inclusion Criteria:

• age below 40 y.o.,
• surgery under spinal anesthesia,
• no previous history of urological problems.

Exclusion Criteria:

• opioid administration during surgery,
• need for urinary bladder catheterization during surgery,
• conversion to general anesthesia.

Patients scheduled for orthopedic surgery under spinal anesthesia.