Aim: To compare the pain-relieving effect of a specific application of TENS vs. placebo TENS and a control group during unsedated diagnostic office hysteroscopy.

Design: double-blind randomized placebo-controlled trial. Setting: Outpatient setting. Population: Women who attended annual gynecological check up, and were indicated for diagnostic office hysteroscopy.

Nowadays, diagnostic hysteroscopy is an easy and economically acceptable technique, that is being used by the gynecologist to evaluate different pathologies that used to be studied by other blind techniques. Although most women tolerate it well, the most common cause for failure during office hysteroscopy is pain. In order to overcome this adversity several studies have been carried out using different types of pain relievers as local anesthesia, misoprostol, music, and NSAID to prevent the occurrence of a vagal reaction, but the results have been contradictory. Other analgesic alternatives that prioritize these three points should be considered. Transcutaneous electrical nerve stimulation (TENS) has become a very common electrotherapy as a pain-reliever because of its attributes, namely a noninvasive and non-pharmacological method based on the delivery of pulsed electrical currents through the skin, using surface electrodes, effective in many variety of conditions, such as neuropathic pain, musculoskeletal pain, headache, gynecological and obstetric pain, to treat both chronic and acute pain, even from visceral organs.

Aim: to compare the pain-relieving effect of a specific application of TENS vs. placebo TENS and a control group during unsedated diagnostic office hysteroscopy.

Design: double-blind randomized placebo-controlled trial. Setting: Outpatient setting; Hospital Provincial de Castellon (Spain) and Hospital General de Castellon (Spain).

Population: Women who attended annual gynecological check up, and were indicated for diagnostic office hysteroscopy

Inclusion Criteria: women who attended annual gynecological check up, and were indicated for diagnostic office hysteroscopy because of different pathologies such as:

• postmenopausal endometrial thickening >4mm;
• postmenopausal abnormal uterine bleeding;
• suspicious endometrial polyp or leiomyoma;
• infertility study;
• suspicious endometrial carcinoma;
• hypermenorrhea

Exclusion Criteria:

• age less than 18;
• previous cervical surgery;
• neurological deficit;
• chronic or preprocedural use of opioids or psychoactive drugs;
• previous experience in TENS;
• cutaneous damage on the application sites;
• pacemakers or automatic implanted cardiac defibrillators;
• refusal to sign the informed consent form;
• inability to understand informed consent form.