Transcutaneous electrical nerve stimulation for pain control during labor and delivery. A case report.

Transcutaneous electrical nerve stimulation (TENS) has been used to diminish postoperative pain and many forms of chronic pain with reportedly good results. There have been few reports of the use of TENS during childbirth in the physical therapy literature. Several European studies have reported good effects of TENS in the reduction of pain associated with labor and delivery. Because TENS is a noninvasive analgesic procedure and no maternal or fetal side effects have been encountered, a firsthand evaluation of this modality seemed appropriate. In this case study, we portray how TENS was used with one patient to prompt physical therapists and other health care providers to develop protocols and conduct research for use of this modality. Melzack and Wall's gate control theory of pain provides one theoretical foundation for TENS. According to this hypothesis, electrical stimulation of the large, afferent, high velocity fibers prevents the smaller, slow velocity, pain-carrying A delta and C fibers from transmitting pain signals to the higher brain centers. In keeping with Melzack's theory, high frequency, low intensity TENS blocks the transmission of nociceptive stimuli to the spinal cord. Labor and delivery are divided into three stages. Stage one begins with contractions of the uterus that efface and dilate the cervix and that cause pain receptors to be activated. The evoked impulses are transmitted by the afferent fibers through the uterine, pelvic, and hypogastric plexes and reach the spinal cord through dorsal roots at T10-L1. Once the cervix is fully dilated (10 cm), the second stage of labor begins; the contractions of the uterus and voluntary contractions of the abdominal muscles push the baby through the vaginal canal. Pain receptors are activated by dilation of the vagina, pelvic floor, vulva, and perineum. The evoked impulses are transmitted by afferent fibers through the pudendal nerves and reach the spinal cord through dorsal roots S2-4. 10 The third stage of labor is the delivery of the baby and the placenta.