There are suggestions from experimental pain studies that pain perception in patients with severe obesity differs compared with individuals with lower BMI values, with a tendency for patients with severe obesity to be hypoalgesic - that is, to have reduced numerical pain scores to a variety of painful stimuli. That finding could be related to: associated reduced cognitive function (complex attention, verbal and visual memory, and decision making) in severe obesity.

The purpose of this study is to determine differences between females' pain levels whether they are obese or non-obese, during different menstrual phases (premenstrual, postmenstrual and menopausal phases) through propofol injection pain given for induction of GA

• Study population Ninety patients, 18 years - 65yor older, physical status ASA I&II, scheduled to undergo elective gynecological surgery, will be enrolled in this prospective observational study.
• Patients' recruitment Patients will be recruited after admission to the hospital, same day they scheduled for surgery. All women who will meet inclusion criteria and gave written informed consent for participation in the study will be enrolled.

Patients will be divided into 2 groups according to BMI levels: Non obese (whether normal weight or overweight) = Group "NO" and obese = Group "O". Normal weight is defined as BMI 18.5-24.9, overweight as BMI 25.0-29.9 and obesity as BMI ≥ 30. [8] This study is a single blind study, where patients are aware of their menstrual status but supporting examiner is not aware of the patients' menstrual status.

Patients will be instructed on a vertical VAS 0-10 cm where (0) is marked as no pain and (10) is marked as the worst pain ever felt After standard anesthesia monitoring, Administration of oxygen will be performed for 3 minutes with 10 L/min fresh gas flow of 100% oxygen. After oxygen administration, 25% of (2 mg/kg) total propofol dose will be injected over 3-5 seconds (Propofol Lipuro 1%, B. Braun Melsungen AG, Germany). The patients will be observed and asked immediately whether they had pain in the arm, its VAS score, type of pain (burning, parathesia or other) and its onset will be documented (to differentiate early or late type of pain).

Another anesthesiologist, who is unaware of the study groups, will assess the intensity of pain after propofol injections.

Inclusion Criteria:

• 18 years - 65yor older,
• physical status ASA I&II

Exclusion Criteria:

• irregular menstrual cycle,
• those who received hormonal therapy for any cause,
• on oral contraceptive pills,
• breast feeding,
• pregnant,
• history of total abdominal hysterectomy and/or bilateral salphingo-opherectomy.
• patients who had difficulty in understanding the visual analogue scale (VAS)/ pain scoring systems,
• renal or hepatic insufficiency,
• anticipated difficult tracheal intubation, and
• hypersensitivity to the study drugs.
• Also, patients on antidepressants and analgesics

Females only

18 years - 65yor older, physical status ASA I&II, scheduled to undergo elective surgery, were enrolled in this prospective observational study

Excel Sheet, individual deidentified participant data will be shared study protocol, statistical analysis plan will be shared