Intrathecal opioid has been known to enhance the quality and prolong the duration of spinal anesthesia, as well as to reduce postoperative pain. A study is to evaluate postoperative analgesic characteristics of intrathecal fentanyl for the first 48 hours after anorectal surgery under saddle anesthesia.

Pain management of surgery not only relieves patients’ pain but also plays an important role in preventing complications after an operation. Postoperative pain is said to be most severe in anorectal surgery, and thus, the choice of anesthetic methods in this procedure is crucial to reduce aches as well as postoperative complications. Anesthetic methods of anorectal surgery such as hemorrhoidectomy, fistulotomy, incision and drainage of perianal abscess vary.

Among them, spinal anesthesia is commonly used for anorectal surgery which does not need a sophisticated machine and which has been performed for years before anesthetic equipment such as mechanical ventilators and monitoring devices was produced. The development of new local anesthetic agents, the use of opioids, and an interest in acute and chronic pain management have universalized spinal anesthesia.

Anorectal disorders are the second most frequent disease by main surgery according to the 2015 statistical yearbook of the National Health Insurance Service in Korea. Anorectal surgery is also associated with the most severe pain among all operations. Thus, pain management is one of the crucial parts for appropriate postoperative patient care. The effects of postoperative pain management include early ambulation and the reduction of adverse effects.

The most common causes of delay in discharge are a pain, drowsiness, and nausea or vomiting. Therefore, an optimal anesthetic method should provide for excellent operating conditions, rapid recovery, fewer postoperative side effects, and high patient satisfaction. Spinal anesthesia is the most widespread anesthetic method. Addition of intrathecal opioid has been established for postoperative pain reduction, but it is unknown whether it is effective in anorectal surgery under saddle anesthesia.

In conclusion, intrathecal fentanyl 15 μg is safe to use and provides satisfactory results for anorectal surgery under saddle anesthesia.

Bupivacaine 5 mg with fentanyl 15 μg for anorectal surgery under saddle anesthesia showed an improved mean NRS score in the first six hours compared to bupivacaine 5 mg with normal saline 0.3 ml. The group with fentanyl also exhibited decreased rebound pain. Pruritus that was a problem in most previous studies occurred less often in our research and instances of hypotension and bradycardia which are problems of spinal anesthesia did not show up.