Study was terminated per Principal Investigator decision.

The study is prospective and double blind. In the clinic, patients undergoing hysterectomy that meet the criteria for inclusion into the study and agreed to participate in the study will be randomized into two groups.

The study is prospective and double blind. In the clinic, patients undergoing hysterectomy that meet the criteria for inclusion into the study and agreed to participate in the study will be randomized into two groups. In the first group of patients will receive Nitrous Oxide and In the second group of patients will receive oxygen during the general anesthesia.

Inclusion Criteria:

• 18 to 65 years old at time of the first procedure
• Female
• American Society of Anesthesiologists physical status I or II
• Hysterectomy undergoing the general anesthesia

Exclusion Criteria:

• Neuropathic disease
• Chronic opioid users
• Contraindication for Nitrous Oxide receive
• Consent will not be obtained patient
• Psychiatric disorders
• Current or recent drug abuse (within past 6 months).