In this prospective randomized study the investigators aimed to investigate difference of the duration of spinal anesthesia, discharge times and efficacy between low dose heavy Prilocaine-Fentanyl and heavy Bupivacaine-Fentanyl in outpatient minor anal surgery.

ASA status I-III patients will be recruited. Patients will be randomized in two groups. Group B will be received 1.5 ml heavy bupivacaine+ 20 mic fentanyl+ 0.15 ml and Group P will be received 1,5 ml heavy prilocaine+20 mic fentanyl in the same volume.Patients will be monitored with electrocardiography, peripheral oxygen saturation(sPO2) and non invasive blood pressure (Drager Infinity Delta; 16 Electronics Avenue, Danvers, MA 01923 USA). After inserting a 20 G intravenous line the patients will be hydrated with 10 ml/kg 0.9 % saline.

Preoperative systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MBP), heart rate (HR) and Spo2 will be measured and recorded.

Spinal anesthesia will be commenced in the sitting position with a 25 G Quincke needle, with the midline approach. After observing free flow of cerebrospinal fluid the prepared study drug will be injected in 15 seconds. The patients will be placed supine after waiting 2 minute in the sitting position. Supplemental oxygen via nasal cannula will be provided.

Fentanyl and midazolam will be used for rescue analgesia and sedation and recorded.

Sensorial block will be assessed with pinprick test with 2 minute intervals until the maximum block achieves and with 15 minute intervals until the block was regresses to S3 dermatome. Motor block will be assessed with the Bromage score when the block reached the maximum level. Patients will be transferred to postoperative care unit (PACU) at he end of surgery.

Pain will be assessed on a 10 point visual analog scale (VAS)(0= no pain, 10= worst pain ever). Postoperative analgesia will be provided with 2 mg.kg-1 tramadol or 15 mg.kg-1 paracetamol when the VAS score is ≥3 time of first analgesic request will be recorded.

Hypotension (≥20% reduced from baseline values) will be treated with ephedrine or iv fluid boluses), bradycardia (HR<45 beat min-1 was treated with atropine) was recorded.

The patients will be asked whether to void before surgery. Bladder volume will be assessed with ultrasonography. Patients with residual bladder volumes ≥400 ml will be placed an urine catheter. Time to first urinate will be recorded.

Patients will be assessed for transient neurologic symptoms(pain in the buttocks and legs)(TNS) and satisfaction after surgery.

TNS will be evaluated with daily telephone calls. Patient satisfaction will be evaluated with global satisfaction scale (1= bad, 2=not satisfied, 3=have no idea, 4=satisfied, 5=very satisfied) Parameters to record; time of entering operation room, duration of surgery, time of intrathecal injection, onset of sensorial block(block at L1), time to reach maximum block level, maximum block level, first analgesic ingestion time, PACU duration, two segment regression, time to L1 regression, time to S3 regression, time to it without help, time to stand up without help, time to walk without help, discharge time, time to first void. TNS, patient satisfaction score.

Inclusion Criteria:

• ASA status I-III

Exclusion Criteria:

• Patients with contraindications for spinal anesthesia,
• hypersensitivity to study drugs