TENS for Suction Evacuation for Termination of 1st Trimester Pregnancies

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.