TENS Unit Can Reduce Pain With Medication Abortion

It can also help with period cramps and during procedures

Medication abortion is approved for up to 70 days of gestation, although there is evidence to show it may be successfully used beyond that limit. The FDA approved method is 200 mg of mifepristone followed by 800 mcg of misoprostol, placed between the gums and the cheek, 24-48 hours later. There are many advantages of medication abortion, such as the greater degree of privacy, not needing a surgical procedure, and a lower cost versus a surgical abortion. One issue with medication abortion is the pain. It’s often described as a “really heavy, crampy period,” but in reality pain is a significant issue for many. In one study, almost 60% of people had severe pain even when acetaminophen and ibuprofen were given and in another study using ibuprofen alone for pain relief, over 50% of people reported severe pain. In most studies, severe pain is 7 or higher on an 11-point scale (0 being no pain and 10 the worst pain imaginable).

Pain control for the uterus (this includes the cervix) is challenging as the nerves that are involved are part of the autonomic nervous system. Blocking these nerves to provide good pain relief can really only be done with injections close to the spinal cord, think an epidural during labor, or with heavy sedation. However, one option that can be used at home, and was explored in a study earlier this year, is a TENS unit.

A TENS is a transcutaneous electrical stimulation device. It is a device that you wear close to your body (see image below) that is connected via wires to electrodes on the skin.

The TENS sends an electrical current across the skin to the nerves. How exactly a TENS reduces pain isn’t truly known, but there are several hypotheses. What we do know is there is good data showing a high-frequency setting or hfTENS is helpful for period pain––up to 80% get some relief. The frequency means the number of electrical pulses per second, and it is measured in Hertz. High frequency is typically 80 Hz or higher. A hfTENS has also been studied for pain with hysteroscopy, where an operating telescope is inserted through the cervix to look inside the uterus. One well-done study showed it was helpful in reducing pain scores. TENS has also been evaluated for an endometrial biopsy, a procedure where a sampling of cells is taken from the lining of the uterus. While the hfTENS didn’t reduce pain during the procedure, it did reduce the pain felt 15 minutes afterwards.  

To look at hfTENS for medication abortion, researchers randomized patients seeking abortion to receive active treatment with a hfTENS or a sham (inactive) hfTENS. Both groups received the same model. However, for those who received the sham device the wires were not connected, so no stimulation was received. The participants were instructed to turn the TENS on when they took the second drug, misoprostol, at home. The frequency setting for the hfTENS was 80 Hz and two sets of electrodes were placed over the lower back and two sets over the lower abdomen. The device used was Chattanooga Primera TENS (you can find one here on Amazon). Patients could turn the intensity of the stimulation up to a maximum of 80 milliamperes. The only issue I have with this study is that the pulse duration, also known as the pulse width, or how long each individual pulse lasted, was not described in the paper. According to the manufacturer, the Chattanooga Primera TENS have a pulse width of up to 250 microseconds. 

What did the study find? Pain scores were lower for those using the active hfTENS, and the median reduction in pain was 2 points on an 11-point scale. This is in line with the pain relief seen in other TENS studies. To be clear, a TENS will not take away all the pain, but most people find a reduction in pain of 2 on an 11-point scale to be meaningful.

In my opinion, a hfTENS is definitely a pain control option for medication abortion. The one listed in the study is $84 on Amazon, but the physical therapists I work with tell me that there are decent models in the $30 range. I also think a hfTENS should be recommended more often for menstrual cramps and for pain during office procedures, such as endometrial biopsies and hysteroscopy. While they have not been studied for IUD insertion, I think there is definitely potential here as approximately 50% of people find pain with an IUD insertion moderate or severe.

If someone wanted to try a TENS what might they do?

There are two placement configurations to consider. Either all 4 electrodes on the back, the upper electrodes corresponding to what we call the T10–L1 level (to cover a group of nerves known as the inferior hypogastric plexus that innervate the uterus) and the lower electrodes to cover the nerves that come out lower down that supply the vagina (this region is S2-S4). This is the configuration used in one of the studies for hysteroscopy. 

The placement used in the study for medication abortion is the upper two electrodes as you see in the image image above and the other two on the lower abdomen. I personally prefer the placement with all 4 electrodes on the back, but people can experiment and see what works best for them (especially if they are trying a TENS for menstrual cramps). For a procedure like a hysteroscopy or an IUD, starting the TENS about 5 minutes before the procedure seems to be the standard in the few studies available. For a medication abortion, the TENS should be started when the misoprostol (second drug) is taken based on the study described above. 

The settings to consider are 80 Hertz for frequency and 200-250 uS (microseconds) for the pulse width, but in one study looking at the TENS for hysteroscopy a pulse width of 400 uS was used with good results. There are other configurations to consider, but that requires more of a discussion about the supposed benefits of the settings. Something perhaps for another post.

The stimulation from the TENS should not be painful or result in muscle contractions. The amplitude or intensity in the study described above was no more than 80 milliamperes. Stimulation should be stopped at an hour, but it can be restarted for another hour if needed. 

If you have a pacemaker, implantable defibrillator, heart condition, or epilepsy, check with your doctor before using a TENS. Also, the electrodes shouldn’t be placed over broken or infected skin. 

While many studies looking at pain with medication abortion report high pain scores, the patients also report a high degree of satisfaction. We should not interpret patient satisfaction with the procedure as the pain being acceptable. People are very satisfied to no longer be pregnant, or looking at other painful procedures, they are very satisfied to find out they don’t have cancer after a hysterosocopy or to have highly reliable long-acting contraception after insertion of an IUD. We need more studies to deliver the right pain relief for those who need it.

In my opinion TENS devices are underused in gynecology. I tell my patients they can “take the edge off the pain,” which obviously means different things to different people, but then again, how else would you describe something that can reduce pain scores by 2 on an 11-point scale? A TENS is not going to take away period pain or make a procedure painless, but it may make it more tolerable and for many people a reduction in 2 points on an 11-point pain scale is a meaningful difference.

References

Goldman AR, Porsch L, Hintermeister A, Dragoman M. Transcutaneous Electrical Nerve Stimuation to Reduce Pain with Medical Abortion. Obstet Gynecol 2021;137:100-7.

Kemppainen V, Mentula M, Palama V, Heiloinheimo O. Pain during medical abortion in early pregnancy in teenage and adult women. Obstet Gynecol Scand 2020;99:1603–1610.

Fiala C, Agostini A, Bombas T, et al. Management of pain associated with up-to-9-weeks medical termination of pregnant (MToP)) using mifepristone-misoprostol regimens: expert consensus based on a systemic literature review. J Obstet Gynaecol 2020;40:591-601.

Raymond EG, Weaver MA, Louie SK, et al. Prophylactic compared with therapeutic ibuprofen analgesia in first-trimester medical abortion: a randomized controlled trial. Obstet Gynecol 2013 Sep;122(3):558-64.

Medication abortion up to 70 days of gestation. ACOG Practice Bulletin No. 225. American College of Obstetricians and Gynecologists. Obstet Gynecol 2020;136:e31–47.

Yilmazer, M., Kose, S., Arioz, D.T. et al. Efficacy of transcutaneous electrical nerve stimulation for pain relief in women undergoing office endometrial biopsy. Arch Gynecol Obstet 285, 1059–1064 (2012). https://doi.org/10.1007/s00404-011-2111-7.

Lisón JF, Amer-Cuenca JJ, Piquer-Martí S, et al. 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.