This document describes the protocol of a pilot randomized clinical study evaluating the effect of environmental visual distraction combined with nitrous oxide (N₂O) analgesia on the procedural experience of patients undergoing outpatient operative hysteroscopy at the Hysteroscopy Unit of ASL Biella.

Office hysteroscopy is widely used for the diagnosis and treatment of intrauterine conditions such as abnormal uterine bleeding, infertility, and endocavitary pathology. Thanks to technological advances and the miniaturization of instruments, many procedures can now be performed in an outpatient setting without general anesthesia. However, pain perception and procedural anxiety may limit patient tolerance and the completion of the examination.

Nitrous oxide is commonly used for analgesia in outpatient hysteroscopy due to its rapid onset, reversibility, and favorable safety profile. It allows effective pain control without deep sedation and enables quick patient recovery after the procedure.

In addition to pharmacological approaches, environmental strategies aimed at reducing anxiety and discomfort are increasingly studied. In this protocol, a virtual environmental window-a wall-mounted screen displaying relaxing videos such as natural landscapes or marine scenes-is used as a visual distraction tool to potentially improve the patient's procedural experience.

The primary objective is to evaluate the effect of the environmental setting on the patient's experience during hysteroscopy, measured using the Visual Analogue Scale (VAS) for pain after the procedure. The secondary outcome is the rate of referral to the operating room following outpatient hysteroscopy. Results will also be stratified by parity and hysteroscopic instrument used.

The study will enroll 50 patients aged 25-60 years who are eligible for outpatient hysteroscopy and nitrous oxide analgesia. Participants will be randomized into two groups using sealed envelopes. The intervention group will receive nitrous oxide combined with visual environmental distraction, while the control group will receive nitrous oxide alone according to routine clinical practice.

After the procedure, patients will complete the VAS pain scale (0-10) to assess the pain experienced during the intervention. Clinical and procedural data will be collected and analyzed using descriptive and exploratory statistical methods. Outcome assessors will be blinded to group allocation.

The study follows international ethical standards, including the Declaration of Helsinki, Good Clinical Practice guidelines, and European data protection regulations (GDPR). Nitrous oxide is part of routine care and is not the experimental component of the study.

Overall, this pilot study aims to explore whether a simple non-pharmacological environmental intervention can reduce perceived pain and improve patient tolerance during outpatient hysteroscopy, providing preliminary data for future larger studies.

Inclusion Criteria:

• Women aged 25 to 60 years

Candidates for outpatient hysteroscopy

Clinically eligible for nitrous oxide (N₂O) analgesia according to routine clinical practice

Able to understand and sign informed consent

Exclusion Criteria:

• Contraindications to nitrous oxide (N₂O), including:

Known or suspected pneumothorax

Severe obstructive pulmonary disease

Confusional state or altered consciousness

Confirmed or suspected pregnancy

Previous major cervical surgery (e.g., conization)

Refusal or withdrawal of informed consent