Article
Transcutaneous electrical nerve stimulation TENS. for adjuvant pain-relief during labor and delivery
B. Kaplana,b,U, D. Rabinersona, S. Luriec, J. Bara,b, U.R. Krieser d, A. Neria,b
a
Department of Obstetrics and Gynecology, Rabin Medical Center, Beilinson Campus Petach Tiq®a, Israel
b
Sackler Faculty of Medicine, Tel A®i® Uni®ersity, Tel A®i®, Israel
c
Department of Obstetrics and Gynecology, Kaplan Hospital, Recho®ot, Israel
d
Pain Management Center, Melbourne, Australia
Received 23 June 1997; received in revised form 16 November 1997; accepted 1 December 1997
Abstract
Objecti®e: We examined the efficacy of transcutaneous electrical nerve stimulation TENS. in general and the new Freemom TENS device LifeCare, Israel . in particular, for pain relief during labor and delivery. Methods: The study group consisted of 104 women. Forty-six nulliparas 44.2%. and 58 multiparas 55.8%. , all of whom used the TENS device for pain relief during labor. All participants completed a questionnaire on the degree of pain relief afforded them by TENS during the delivery and related questions. The objective evaluation was based on the documented labor and delivery parameters including medical interventions during delivery. Results: The majority of subjects 72% of the nulliparas and 69% of the multiparas. considered TENS effective for the relief of pain during labor. Most of them 67% of the nulliparas and 60% of the multiparas. responded positively to the use of TENS in future deliveries. Sixty-five percent of the multiparas considered TENS at least as effective as the other pain relief methods they had used before. TENS significantly reduced the duration of the first stage of labor P-0.001 for nulliparas, P-0.005 for multiparas and it significantly decreased the amount of analgesics administered to individual patients. No significant difference was found in fetal heart rate tracings, Apgar scores and cord blood pH between the study group and an equal number of matched controls who used other forms of pain management. Conclusions: TENS is an effective non-pharmacological, non-invasive adjuvant pain relief modality for use in labor and delivery. TENS application reduced the duration of the first stage of labor and the amount of analgesic drug administered. There were no adverse effects on mothers or newborns. Q 1998 International Federation of Gynecology and Obstetrics
Keywords: TENS; Delivery; Labor; Pain; Treatment
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252
B. Kaplan et al. rInternational Journal of Gynecology & Obstetrics 60 (1998) 251]255
1 . Introduction
Transcutaneous electrical nerve stimulation TENS. is a non-pharmacological, non-invasive 80%, intact membranes and an expressed desire for pain relief on admission.
Of the 104 patients, 46 44.2%. were nulliparas and 58 55.8%. multiparas. At entry to the delivery room, each patient was fitted with obstetric electrodes laterally to the mid-line between S2 and T10. and the TENS device was connected to the electrodes. The patient was handed a questionnaire to evaluate TENS efficacy in relieving pain during labor and delivery. The items also covered demographic data and medical and obstetric history. TENS efficacy during labor was evaluated by having each participant rank the level of pain sensation every 2 h on a scale of 1 very low. to 10 very high.. Patients were able to control the device manually and the readings were taken while TENS was turned on, or off by the patient., for the time that it took two contractions to occur. We arbitrarily defined TENS as efficacious if the subject consistently scored the pain level as lowered by at least four points. Multiparous subjects were asked to record the type of analgesia used during previous deliveries and to compare their efficacy to the pain management achieved with TENS.
pain-relief method that has been proven effective for a variety of conditions w1,2x . It has also been favorably reported for use during labor and delivery, with an efficacy rate as high as 96% w3,4x . When TENS was applied, the duration of labor was shorter and there was no increase in pathological cardiotocographic findings for either primiparas or multiparas w5x . Most patients were satisfied with TENS and expressed a desire to use TENS again for their next labor w6x .Despite these findings, the use of TENS has received little attention in the US w6x and has gained little popularity among obstetricians worldwide w3x . Two later reports w7,8x have ques-tioned the use of TENS as an efficacious technique of pain relief during labor.
However, our group has since demonstrated excellent results in patients with primary dys-menorrhea who used TENS w9,10x . Based on these results and our overall experience w11x , a new TENS device was designed according to our spec-ifications for use during labor and delivery. The findings of our evaluation are described herein.
On a scale of 1 no difference . to 10 much
2 . Materials and methods
The study population included 104 of the 1953 parturients 18.8%. admitted to the delivery room of Rabin Medical Center, Beilinson Campus from August 1995 to February 1996; all of whom were offered the use of TENS for pain relief during labor. Each received a full explanation of the mechanism and mode of action of TENS. The TENS model employed in this study Freemom, LifeCare, Israel . more efficient., TENS was arbitrarily defined as efficacious when the patient ranked it higher by six points or more over the other forms of pain management. All subjects were asked if they would use TENS for future deliveries.
Patients who did not obtain sufficient pain relief using TENS, were allowed to choose one of the two analgesic pain relief methods used in our delivery room: meperidine qpromethazine or epidural block. For those who chose the former, TENS was continued as an adjuvant therapy. The subjective pain measurements were performed as long as the patient was using TENS alone. They were stopped once the patient elected to use an additional pain-relief method.
To gain an objective picture, the following parameters were recorded for each participant: duration of first stage delivery from admission to

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other pain relief therapy. If meperidine q promethazine was chosen, the number of times medication was requested; Apgar scores at 1 and 5 min; and cord blood pH.
To further validate the results, the same parameters were recorded from an equal number of control patients that were matched for age, parity and gestational week, who used only meperidineqpromethazine or epidural block for pain management.
All study participants signed an informed consent form.
Statistical analysis was performed using Student’s t-test or x 2-test as indicated. A P value less than or equal to 0.05 was considered signifi-cant.
3 . Results
The mean age of the participants was 24"3.5
years range 18]40 years., parity 2.3"1.1 range
0 ]5.
and gestational
age at
delivery 40.5"1.5
weeks range 38]42. .
Data were gathered for nulliparas and multi-paras separately. TENS was considered effica-cious i.e. it reduced the level of pain by 4 points
or more on a scale of 1]10.
by 72%
of the
(1998)
251]255
253
TENS at
parous group, 65% 38r58. favored
least a 6-point higher rating.
over other types of
intrapartum analgesics to which they had been previously exposed.
Table 1 outlines the effects of TENS throughout labor. Compared to the group of match controls, the use of TENS significantly reduced the duration of the first stage of labor, nulliparas, 720"235 min in the study group, 856"255 min in the control group; for multiparas, 520"163 min and 612"184 min, respectively.
Of the TENS users, 67% of the nulliparas and 60% of the multiparas asked for additional anal-
gesia meperidine qpromethazine
or epidural
block. . However, all these requests were made at a significantly higher degree of cervical dilatation compared to the controlled group nulliparas, 5.2
"1.1 cm and 2.5"0.5 cm; multiparas, 7.1"2.1 cm and 4.0"1.5 cm, respectively..
Rates of pathological FHR tracings, as well as 1 and 5 min Apgar scores and cord blood pH, were similar in the TENS participants and the controls.
4 . Discussion
Only a small percentage of women who deliver
nulliparas 33r46. and
69% of
the multiparas
40r58. . Most of the participants
in both
sub-
in hospitals receive no pain medications. The most frequently employed form of pain control during labor is epidural analgesia 50%. , followed by narcotics 26%. , w12x . Although these agents apparently meet the needs of most parturients,
groups who favored TENS 67% of the nulliparas, 60% of the multiparas. stated that they would use TENS again for their next labor. In the multi-
Table 1
Effect of TENS on intrapartum parameters
Study group
Control group
P
P
Nulliparas Multiparas Nulliparas Multiparas Nulliparas. Multiparas.
Duration of first
720"235 min 520"163 min
856"255 min 612"184 min
0 .001
0 .005

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254 B. Kaplan et al. rInternational Journal
they are not without contraindications and com-
plications w13x .
This was
the rationale
for our
search for an alternative, safe and non-pharmacological method of intrapartum pain relief.
TENS operates by the application of electrical impulses through conductive electrodes placed on the skin. Analgesia is attributed either to the increase in A-fiber transmission which blocks pain impulses to the brain., the ‘gate theory’ of Melzack and Wall w14x , or to the stimulation of the local release of endorphins w15x . TENS has been proved to be generally effective in a variety
of conditions w1,2x and delivery w3,4x .
and specifically during labor
Patients, who have used TENS for pain relief during labor, have expressed their satisfaction w4x and no pathological FHR tracing w5x or adverse effects on the newborn have been noted w7x . Some authors have also highlighted the beneficial TENS
in reducing the duration of labor w5x ,
but this
finding has been negated by others w7x . The present series is one of the largest studying TENS use during labor. We evaluated the efficacy of a new TENS device, which was designed and constructed in Israel according to our specifications w11x , based on our favorable experience with TENS
for primary dysmenorrhea w9,10x . Others, w6x
have
also examined the efficacy of a locally produced
US-made design.
device. It should
be empha-
sized that the efficacy of the specific device
Freemom, LifeCare, Israel .
rather than
the
modality itself TENS. was examined. The analgesic effect was also investigated both; subjectively, by self-report questionnaire and objectively, by different intrapartum and neonatal outcome parameters. Our study used similar techniques to those employed in earlier work studies that examined TENS use during labor and deliv-
ery
w4]10x
(1998)
251]255
obstetric history or previous use of pain relievers during labor, found TENS effective for the management of labor pain. Nevertheless, a considerable proportion requested an adjuvant pain-relief method later, during delivery. Apparently, the labor pains intensified towards the second stage of labor, TENS was not sufficiently effective. Therefore the use of TENS may serve parturients at the beginning of the first stage; those who requested additional pain relief treatment did so at a later stage with significantly higher degrees of cervical dilatation, thereby minimizing the total intake of potentially hazardous analgesic drugs w5,12,16x .
The favorable potential of TENS on the one hand and the need for other types of pain-relief on the other, may need further improvements in the design of devices aimed specifically to cope with the quality of pain of labor w4x . Most parturients, including multiparas who have been exposed to other methods of pain-relief during labor, expressed a desire to use TENS again for their next delivery. TENS also significantly shortened the duration of labor.
Although we have described only the findings relevant to the first stage of labor, the same trend was noted for the second stage as well. These results were not incorporated here because the possible prolongation of the second stage in those parturients who received an epidural block may here have biased the results w17x . A possible explanation for the second stage findings is the decrease in maternal discomfort and anxiety afforded by TENS pain relief, which was achieved immediately on admission to the delivery room. TENS decreases catecholamine release because
the epinephrine
inhibits uterine
activity w12x .
Therefore the alleviation of pain obtained by TENS may have a beneficial effect on the progress of labor as well w12x . Indeed, 33% of the nulli-

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meperidineqpromethazine.
is US$1 and two to
three doses are required during normal labor. Assuming 3000 annual deliveries and taking into account that TENS can reduce analgesic consumption by one-third w5x , the use of six TENS devices in our six delivery rooms yields considerable savings.
In conclusion, the Freemom TENS model has proven beneficial for pain relief during labor and has no adverse effect on mother or newborn. We believe that the use of this modality should be expanded so that clinicians might gain more experience with it and more parturients can benefit from it.
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