Transcutaneous Electrical Nerve Stimulation (TENS) for pain relief during labor

by | May 22, 2018

Welcome!

Today’s video is all about using TENS during laborAs a reminder, here is our disclaimer and terms of use. | Photo Credit: Toni Nichole Photos

You’ll learn:

  • What TENS is
  • How TENS might work to provide pain relief during labor
  • What the evidence shows about using TENS during labor

Watch, Read or Listen:

To read, please view the transcript below. To listen, subscribe to our podcast:  iTunes  |  Stitcher 

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View the transcript
Hi, everyone! My name’s Rebecca Dekker, and I’m a nurse with my PhD and the Founder of EvidenceBasedBirth.com. In today’s video we’re going to talk about using TENS, or transcutaneous electrical nerve stimulation, for pain management during labor.

What is TENS?

TENS is a non-drug, or non-pharmacological way to help manage pain. You can buy TENS units online or at a local drugstore. I picked this one up from the Walgreens down the street from me and it cost about $30. TENS consists of a handheld, portable device that is connected to electrodes. Electrodes typically come on these pads. This is a small pad, and this here is an example of a larger pad, both still in their packaging. You would connect the unit to those electrodes, either directly or sometimes using wires. You would then place the pads on the body. Through the electrodes, mild electrical pulses are sent through the skin and the body to the person’s spinal cord and brain.

When you’re using TENS during labor, you might feel a buzzing, tingling, or prickling sensation wherever the pads are placed. It’s easy to administer, and the person who is receiving the TENS can control the intensity of the sensation using the buttons on the device.

TENS during labor is most frequently applied to the lower back, on either side of the spine. Mothers can adjust the intensity of the TENS unit as needed during contractions. TENS can also be applied by trained specialists to acupuncture points. TENS can be used in combination with other non-drug and drug methods of pain relief – except with hydrotherapy, or water immersion. You shouldn’t be using it anywhere near water. It’s also not supposed to be used together with heat. TENS therapy can be stopped at any time, and does not have any residual effects. For example, you could stop it if you wanted to get into the tub or remove the electrodes to have a back massage.

History of using TENS for pain relief

TENS units have been used to relieve pain for a variety of conditions since the 1970s. TENS has been used for menstrual cramps, arthritis, and several other chronic pain conditions. The FDA has actually approved TENS for use post-surgery and for traumatic pain. Interestingly, the history of using TENS for pain relief may date as far back as the year A.D. 63, when the physician to the Roman emperor reported that he could relieve pain by standing on electrical fish at the seaside.

TENS first started being used during labor in the 1970s, but it started to become more popular in the 1990s. Its use really varies by country. For example, in a 2009 survey of most birthing units and hospitals in England, they found that all 139 of those maternity care units supported and encouraged the use of TENS during labor. However, only about one in five of the maternity care units had their own TENS units that women could borrow during labor. The rest of them expected the consumer to come in with her own TENS unit to use.

How might TENS work to help manage pain?

Well, researchers think that TENS might work by changing how a person perceives their pain. If you haven’t already, I highly recommend that you go back and watch our video all about the overview of pain management during labor. In that video, we talk about the different ways that pain management techniques might work.

Low-Intensity TENS and Gate Control Theory

When you use TENS at a low-intensity level, it is probably working through the Gate Control Theory. The Gate Control Theory says that there’s only a certain amount of stimuli that can get through to the brain. In other words, there is a “gate” that only lets so much sensory information through. So, with TENS, you’re kind of flooding the brain with this sensory buzzing feeling so that the brain can’t really perceive the sensation from labor contractions as much.

High-Intensity TENS and Diffuse Noxious Inhibitory Control

However, if you are using high-intensity TENS (with the intensity turned way up), researchers think it might work to relieve pain in a different way. The idea behind this other mechanism, which has a long name called Diffuse Noxious Inhibitory Control, is that by stimulating the body with another source of pain, you trigger the body to release its own natural pain relieving hormones called endorphins. In other words, you’re creating a painful sensation to encourage your body to release those endorphins, which act kind of like your own morphine supply.

Researchers also think that TENS during labor might work by decreasing anxiety, making you feel like you have more control over your labor, and by providing a distraction from labor contractions.

How do I select a TENS unit and learn to use it?

There are a variety of different types of TENS units available. Mothers typically report that they like the larger pads because labor pain can be spread out. Mothers also report that they like having a boost button that they can push as needed during a contraction. The TENS unit that I purchased does not have that button, but there are some on the market that do have a boost button.

TENS can be purchased by consumers without a prescription. Like I said, I just went to my local drugstore and got one. TENS can really be used without any special training other than reading the very long safety insert. However, there are options for doulas and other healthcare professionals to get formal training in how to use TENS safely and effectively. I’ll link to some of those trainings in the blog article for this video. In the research articles that I’m going to talk about in just a minute, TENS was often applied to the lower back without any special training, but in some studies there was a trained acupuncturist who applied it to special acupuncture points.

What is the evidence on using TENS during labor?

We found three systematic reviews of the research; all were published in the year 2011. Because they had similar findings and looked at similar studies, we’re going to focus on the Cochrane Review from 2011.

Dowswell et al. (2011) Cochrane Review and Meta-Analysis

In this review, researchers combined 17 randomized controlled trials with about 1,500 participants total. The control groups varied between the studies. Some of them used routine care, some of them used a placebo TENS (where they applied it to the back but didn’t turn the unit on, or used an extremely low intensity), and some of them compared TENS to other methods of non-drug pain relief. Overall, 10 of the 17 trials were placebo-controlled with a TENS unit that was either not turned on or had a very low electrical current. Unfortunately, some of the participants in the studies may not have been truly blinded to what treatment they were receiving – the true treatment or the placebo – because it’s possible that they may have realized that their TENS unit was not turned on.

Overall, there was little difference in pain ratings between people who had TENS and people in the control group. However, they found that people using TENS applied to acupuncture points were less likely to rate their pain as severe compared to the control group. More people who were assigned to true TENS were likely to say that they wanted to use it in future labors compared to those in the placebo group. However, a surprising number of people in the placebo group also reported that they would like to use that treatment in future labors (not knowing that it was a placebo). This suggests that simply having the TENS unit applied to you, whether or not it’s turned on, may help by distracting you from labor and giving you a sense of control.

There were three studies that looked at using TENS in addition to an epidural. So, people had an epidural and they were also randomly assigned to have TENS during labor or not. The researchers found that it did not provide any additional benefits to reducing pain levels when you add TENS to an epidural.

There were no bad outcomes or adverse events in any study; however, there may have been some skin irritation under some of the pads. There was one case in all of the studies where the TENS did interfere with electronic fetal monitoring, but that only happened with one patient.

Since that 2011 review came out, there have been three more randomized controlled trials on this topic that were too new to be included in that review.

Shahoei et al. (2017)

In 2017, researchers from Iran reported the results of their randomized controlled trial where they assigned 90 first-time mothers to low intensity TENS, placebo TENS (where the device was turned off), or to routine care. They started the treatment on the back at about four centimeters dilation, and the treatment continued until the time of birth.

After about one hour, the average pain scores were not different between the groups; however, they saw significant differences in pain levels at two, three, and four hours after the treatment began. For example, in the second stage of labor, during the pushing phase, only 20% of the people in the TENS group reported their pain as severe compared to about 83% – 87% of people in the other two groups. When they asked people about four hours after the birth how they recalled the severity of their pain, only 7% of people in the TENS group recalled severe pain compared with 43% of people in the placebo group, and 60% of people in the standard care group.

Santana et al. (2016)

In another study, researchers in Brazil randomly assigned 46 first-time mothers to either TENS or standard care. They did not attempt to use a placebo TENS in this study. In the experimental group, once mothers reached four centimeters dilated, TENS was applied once to the back for 30 minutes. The intensity of the TENS was determined by the person who was laboring.

Before they started the intervention, about 70% of people in both groups reported that their pain was a seven or higher on the zero to ten pain scale. But after the intervention, only 34% of people in the TENS group said that their pain was a seven or higher compared with 83% in the standard care group.

On average, people who were randomly assigned to receive TENS ended up waiting about seven hours before they requested additional medication for pain relief compared to two hours in the group that did not receive TENS. So, TENS may have helped the people in the treatment group postpone their need for pain medication. This study found no differences in reports of maternal satisfaction with TENS or no TENS.

Shaban et al. (2013)

Finally, in 2013, researchers in Egypt randomly assigned 100 people in active labor to either receive low-intensity TENS applied to the back, or to receive Pethidine/Demerol, which is an injectable narcotic. TENS was used in the experimental group until the participants reached 10 centimeters dilation.

They found a decrease in pain scores in both groups, but there was no significant difference between the groups. Forty-eight hours after the birth, the people who were randomly assigned to receive TENS during labor were much more satisfied with their birth, on average, compared to the people who received the injectable pain medication. Of those who received TENS, 83% reported being satisfied compared with only 10% of those who received Demerol.

In addition to low satisfaction, the people who received Demerol also reported side effects such as drowsiness, nausea and vomiting. Babies in the Demerol group also had lower Apgar scores after birth. There were no bad side effects reported in the TENS group. The results from this study are not surprising. If you look at our video about using IV opioids, or injectable opioids during labor, Demerol is considered to be a not safe option because of its effects on babies and mothers in terms of their breathing.

Conclusion

In summary, there is a need for more high quality research on this topic. At least 11 randomized controlled trials have attempted to compare true TENS to a placebo TENS, where the device is either turned off or at a very low intensity. However, we’re not quite sure if those researchers did a good job of blinding, or making sure that people who received the placebo were blinded to the fact that they were receiving a placebo.

There is some evidence from the Cochrane Review and from the recent randomized controlled trials that using TENS during labor does decrease pain and may increase maternal satisfaction. Most people who use TENS say that they would use it again in a future labor. There was also one recent randomized controlled trial that found that the use of TENS delayed or postponed the use of medications for pain relief.

TENS applied to the lower back during labor does seem to lower pain compared to placebo or routine care. One recent study that compared TENS to injectable opioids found that TENS relieved pain just as well as the injectable opioids, but without causing side effects for the mothers and babies. So far, researchers have not reported any bad side effects on mothers or babies from using TENS during labor; however, there has been limited research in this area.

The bottom line is that the available evidence does support the use of TENS during labor as an option for pain management.

I hope you enjoyed this video! Please feel free to check out our other videos in our pain management series. We also have a series all about natural labor induction methods. Thanks, bye!

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