TENS for Suction Evacuation for Termination of 1st Trimester Pregnancies

A Doubled Blinded Randomised Controlled Trial of Conscious Sedation With Transcutaneous Nerve Stimulation for Pain Relief During Suction Evacuation for Termination of First Trimester Pregnancies

To study the effectiveness of the pain relief method of transcutaneous electrical nerve stimulation (TENS) for women who will undergo suction evacuation under conscious sedation for first trimester termination of pregnancy.

Suction evacuation is a minor gynecological procedure commonly performed at an outpatient setting for termination of pregnancy. Although it is a simple surgical procedure lasting 5-10 min and can be done under various methods of pain control, 78-97% of women still report at least moderate procedural pain, especially during injection of paracervical block, cervical dilation, suction aspiration and postoperatively with uterine cramping. In addition, those pharmacological analgesic methods are often associated with numerous adverse effects and cannot be applicable to all women. The transcutaneous nerve stimulation (TENS) method is commonly used to treat labour pain. It is an inexpensive, quick, easy to use and noninvasive pain relief method. A recent study by Lison et al. on TENS for office hysteroscopy demonstrated a significant decrease in pain scores when compared to control and placebo groups. The rationale of TENS lies in achieving pain reduction when electric stimulation alters the nociceptive transmission in the dorsal horn of the spinal cord; this means the electrode has to be adequately applied in the right receptive field of the body to achieve pain control. For the setting of TENS there is evidence supporting superior pain relief by random high frequencies TENS over fixed frequency. Increasing the pulse duration to above 250 microseconds also produces better analgesics effect. In suction evacuation, the nerve roots of T10-L1 and S2-S4 becomes relevant as they correspond to the nerve supply to the whole uterus and cervix. Lison et al placed electrodes at these levels parallel to the spinal cord in their study and have instructed their subjects to increase the TENS intensity to the maximum nonpainful level, allowing further increase when their stimulus perception decrease as a result of nerve accommodation. Its use in suction evacuation however, remains undetermined as there is no published study in this area.

After the written informed consent is obtained, subjects will be randomly allocated into one of the two groups: (a) the active TENS group and (b) the placebo TENS group.

To measure patient's pain intensity before and after suction TOP by using The Visual Analogue Scale (VAS) consists of a straight line length of 100 mm with the endpoints defining extreme limits such as 'no pain at all' and 'pain as bad as it could be'. The patient is asked to mark his pain level on the line between the two endpoints. The distance between 'no pain at all' and the mark then defines the subject's pain. This tool was first used in psychology by Freyd in 1923.

Patient will be asked for the pain intensity by using the 100 mm linear VAS 5 minutes before receiving the active TENS/ placebo TENS before the start of suction evacuation, reassess 20 minutes later and 1 hour after operation.

To assess the change of Anxiety level of the patients in 3 time points by using State-Trait Anxiety Inventory Questionnaire to record patient's anxiety level.

Patient will be asked for the anxiety level by using STAI 5 minutes before receiving the active TENS/ placebo TENS before the start of suction evacuation, reassess 20 minutes later and 1 hour after operation.

The surgeon will assess the difficulty of the operation by using LEVEL OF SEDATION AND DIFFICULTY OF OPERATION ASSESSMENT FORM (proposed by Ramsay et al.)

The surgeon will be asked to fill the assessment form right after the suction evacuation operation immediately.

Inclusion Criteria: Chinese aged 18 years or above and mentally competent Up to 12 weeks gestation on the day of STOP Size of the uterus on pelvic examination compatible with estimated duration of pregnancy, or dating confirmed with ultrasound scan Normal general and gynecological examination Exclusion Criteria: Skin damage or allergy at site of TENS pads application Previous experience with TENS History of pacemarker insertion History of severe respiratory or cardiac disease Severe and recurrent liver disease Allergic to lignocaine Myasthenia gravis Psychiatric conditions requiring medication Disorders that constitute contraindications to use of prostaglandins

Belanger E, Melzack R, Lauzon P. Pain of first-trimester abortion: a study of psychosocial and medical predictors. Pain. 1989 Mar;36(3):339-350. doi: 10.1016/0304-3959(89)90094-8.

Wong CY, Ng EH, Ngai SW, Ho PC. A randomized, double blind, placebo-controlled study to investigate the use of conscious sedation in conjunction with paracervical block for reducing pain in termination of first trimester pregnancy by suction evacuation. Hum Reprod. 2002 May;17(5):1222-5. doi: 10.1093/humrep/17.5.1222.

Lison JF, Amer-Cuenca JJ, Piquer-Marti S, Benavent-Caballer V, Bivia-Roig G, Marin-Buck A. Transcutaneous Nerve Stimulation for Pain Relief During Office Hysteroscopy: A Randomized Controlled Trial. Obstet Gynecol. 2017 Feb;129(2):363-370. doi: 10.1097/AOG.0000000000001842.

Vance CG, Dailey DL, Rakel BA, Sluka KA. Using TENS for pain control: the state of the evidence. Pain Manag. 2014 May;4(3):197-209. doi: 10.2217/pmt.14.13.

Sluka KA, Walsh D. Transcutaneous electrical nerve stimulation: basic science mechanisms and clinical effectiveness. J Pain. 2003 Apr;4(3):109-21. doi: 10.1054/jpai.2003.434.