Caudal epidural block has been widely used, especially in pediatric surgery, to provide intraoperative and postoperative analgesia by affecting the region between T10 and S5 dermatomes in surgeries below the umbilical level.

In conventional single-shot caudal block, the needle is inserted through the skin with a 60-80 degrees angle, until the sacrococcygeal ligament is passed through. Then the angle of the needle is decreased to 20-30 degrees and inserted further for an additional 2-3 mm, entering into the sacral canal.There is a risk of dural or vascular puncture when the needle is passing through sacral canal. Other complications are the soft tissue bulging, intraosseous injections and systemic toxicity.

Many anatomical variations have been reported for sacral hiatus and sacral cornua. Therefore, the success rate of the classic caudal epidural anesthesia method in pediatric patients has been reported to be about 75%.

With the usage of ultrasonography in regional anesthesia, many advantages have been reported. Ultrasonography is helpful for visualization of the sacral hiatus, sacrococcygeal ligament, duramater, epidural space and the distribution of the local anesthetic agent within the epidural space. Therefore, this significantly increases the block success.

The primary aim of this study was compare the success rate of ultrasound guided sacral hiatus injection and conventional sacral canal injection. Secondary objectives are; block performing time, number of needle puncture, success at first puncture and complication rate.

Inclusion Criteria:

• American Society of Anesthesiologist's physiologic state I-II patients undergoing phimosis and circumcision surgery

Exclusion Criteria:

• children with severe systemic disease
• previous neurological or spinal disorder,
• coagulation anomaly
• allergy against local anesthetics
• local infection at block site or
• with a history of premature birth