Content uploaded by Ana Carolina R Pitangui
Author content
All content in this area was uploaded by Ana Carolina R Pitangui on Nov 09, 2018
Content may be subject to copyright.
High-frequency TENS in post-episiotomy pain relief in
primiparous puerpere: A randomized, controlled trialjog_1824 980..987
Ana Carolina Rodarti Pitangui1,3, Ligia de Sousa1, Flávia Azevedo Gomes1,
Cristine Homsi Jorge Ferreira2and Ana Márcia Spanó Nakano1
1College of Nursing and 2Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Faculty of
Medicine, University of San Paulo, Ribeirão Preto, and 3Department of Physiotherapy, University of Pernambuco,
Petrolina, Brazil
Abstract
Aim: We evaluated the effectiveness of high-frequency transcutaneous electrical nerve stimulation (TENS) as
a pain relief resource for primiparous puerpere who had experienced natural childbirth with an episiotomy.
Methods: A controlled, randomized clinical study was conducted in a Brazilian maternity ward. Forty puer-
pere were randomly divided into two groups: TENS high frequency and a no treatment control group.
Post-episiotomy pain was assessed in the resting and sitting positions and during ambulation. An 11-point
numeric rating scale was performed in three separate evaluations (at the beginning of the study, after 60 min
and after 120 min). The McGill pain questionnaire was employed at the beginning and 60 min later. TENS with
100 Hz frequency and 75 ms pulse for 60 min was employed without causing any pain. Four electrodes ware
placed in parallel near the episiotomy site, in the area of the pudendal and genitofemoral nerves.
Results: An 11-point numeric rating scale and McGill pain questionnaire showed a significant statistical
difference in pain reduction in the TENS group, while the control group showed no alteration in the level of
discomfort. Hence, high-frequency TENS treatment significantly reduced pain intensity immediately after its
use and 60 min later.
Conclusion: TENS is a safe and viable non-pharmacological analgesic resource to be employed for pain relief
post-episiotomy. The routine use of TENS post-episiotomy is recommended.
Key words: episiotomy, non-pharmacological pain treatment, postoperative pain, postpartum period,
transcutaneous electrical nerve stimulation.
Introduction
Pain from perineal trauma has been reported to be one
of the most common causes of maternal morbidity in
the post-childbirth period.1,2 Women with an epi-
siotomy have experienced greater pain and may be
subjected to greater blood loss, hematomas, infections,
dehiscence, sexual dysfunction, vaginal prolapse and
rectovaginal fistula in comparison to other types of
perineal trauma.3In addition, these injuries can affect
many activities, such as walking, sitting, sleeping,
urinary and intestinal movements, self-care, care of the
newborn, the efficiency and ease of lactation, sleep and
appetite.1,4
Recently, some researchers have carried out studies
with the aim of investigating therapeutic measures that
Received: April 27 2011.
Accepted: October 29 2011.
Reprint request to: Dr Ana Carolina Rodarti Pitangui, Departamento de Fisioterapia, Universidade de Pernambuco, Br 203 Km 2 s/n,
Campus Universitário, Vila Eduardo, Petrolina, 56328-903 Pernambuco, Brasil. Email: carolpitangui@hotmail.com
Scientific address where project was executed: College of Nursing, University of São Paulo, Ribeirão Preto, São Paulo, Brazil.
Place where the study originated: College of Nursing, University of São Paulo, Ribeirão Preto – EERP/USP, São Paulo, Brazil.
Registration number – ACTRN: ACTRN12610000471088.
bs_bs_banner
doi:10.1111/j.1447-0756.2011.01824.x J. Obstet. Gynaecol. Res. Vol. 38, No. 7: 980–987, July 2012
980 © 2012 The Authors
Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology
are capable of mitigating the pain associated with an
episiotomy; however, this subject is incipiently and
infrequently approached in the literature. Both phar-
macological and non-pharmacological methods have
been employed as treatment for this discomfort.2
Medication therapy consists of the use of non-
hormonal oral analgesics and anti-inflammatory
agents that are applied to the injured area;1,5 non-
pharmacological resources commonly include the use
of hot and cold compresses and vaginal washes.1,5
However, there are few studies capable of supporting
the effectiveness of non-pharmacological techniques,
and the observations that follow them are frequently
supported by opinions.1,5,6
Transcutaneous electrical nerve stimulation (TENS)
consists of an easily handled, low-cost, non-
pharmacological, non-invasive resource that is associ-
ated with minimal side effects and sends electrical
impulses through the skin to control the pain.7,8
Although studies have demonstrated the effective-
ness of TENS in countless surgical procedures,9,10 no
previous study has attempted to investigate the effect of
TENS on post-episiotomy pain using local application
in the perineal area. Hence, the objective of this study
was to evaluate the effectiveness of high-frequency
TENS as a pain relief resource employed in primiparous
puerpere who had experienced natural childbirth with
an episiotomy.
Patients and Methods
Participants
This was a controlled, randomized clinical study. Forty
primiparous puerpere in a Brazilian maternity ward
who had experienced a spontaneous vaginal delivery
with an episiotomy were randomly selected into two
groups: high-frequency TENS (n=20) versus no treat-
ment control (n=20). All participants voluntarily
signed a Free and Informed Consent Form. The study
was approved by the Research Ethics Committee of the
Nursing School of Ribeirão Preto in the University of
San Paulo, Brazil.
The volunteers were randomly placed in the active
(TENS) group or the no treatment control group using
a computer-generated randomization sequence. Ran-
domization occurred in the order in which participants
were enrolled in the study according to the computer-
generated randomization list prepared prior to the start
of the study. A blocking randomization was pro-
grammed to generate a sequence of allocation to ensure
that there was a close balance of the number of subjects
in each group throughout the study. The women were
randomized into the active and the no treatment
groups with a 1:1 ratio. The trial design is presented in
Figure 1.
Sample size calculations were previously deter-
mined in a pilot study with 15 puerpere. Reductions in
Figure 1 Trial design. TAF, high
frequency transcutaneous elec-
trical nerve stimulation.
Assessed for eligibility
(
n = 51
)
Excluded (n = 11)
Not meeting the inclusion criteria
(n = 9)
Refused to participate in the study
(n = 2)
Randomized
(
n = 40
)
Allocated to TAF group
(
n = 20
)
Allocated to control group
(
n = 20
)
Lost to follow up or
discontinued the protocol
(n = 0)
Lost to follow up or
discontinued the protocol
(n = 0)
Analyzed (n = 20)
Excluded from analysis
(n = 0)
Analyzed (n = 20)
Excluded from analysis
(n = 0)
High-frequency TENS in post-episiotomy
© 2012 The Authors 981
Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology
pain scores following the intervention were used as the
measurement parameter. A reduction of 1.3 points11,12
in the 11-point numeric rating scale was considered to
be clinically relevant with a standard deviation of 1.47
and 1.25 for the TENS group and control group, respec-
tively. An a=0.01 and power =90% (b=0.1) required a
sample size of 20 individuals in each group.
Inclusion and exclusion criteria
Inclusion criteria were: (i) low risk primiparous preg-
nancy; (ii) older than 18 years of age; (iii) literate,
understanding the Portuguese language; (iv) aware of
time and space; (v) post-vaginal spontaneous delivery;
(vi) experienced an episiotomy with stitches; (vii) pre-
senting pain in the episiotomy area; and (viii) absence
of any genitourinary pathology. Exclusion criteria
were: (i) contraindications to TENS, such as open
wounds; (ii) puerperal complications (increased bleed-
ing requiring intervention, physiological signs sug-
gesting infection, fever, anesthesia complications,
hypertension or breast conditions); (iii) previous expo-
sure to TENS or electrical stimulation; (iv) morbid
obesity; and (v) instrumental delivery (i.e. use of
forceps).
Apparatus and TENS treatment
TENS treatment was performed using a portable appli-
ance model (Tens KW Compact; KW Indústria Nacio-
nal de Tecnologia e Eletrônica, San Paulo, Brazil),
which generates a balanced pulse of biphasic, asym-
metric waves with control switches for frequency varia-
tion and amplitude. Four silicone-carbon electrodes
(5.5 cm ¥3 cm) were placed on the skin parallel to the
episiotomy site (Fig. 2). The region corresponds to
the pudendal and genitofemoral nerves that supply
the perineal area. TENS was applied with 100 Hz
frequency and 75 ms pulse for 60 min.13 The increase
in the electrical impulse intensity was guided by the
participants. They were instructed that the intensity
should result in a strong numbing sensation, but with
no muscle contraction. The TENS appliance was cali-
brated at the beginning of data collection by a digital
oscilloscope.
Procedures
The institution’s routine protocols include limited
episiotomy use. When required, episiotomies are per-
formed using a mediolateral incision with local anes-
thesia. During labor, the patients can receive epidural
analgesia and in the postpartum period they can receive
medications and ice packs. The medications used are
dipyrone (metamizole) taken orally or intravenously
and diclofenac (a non-steroidal anti-inflammatory
drug) taken orally or by intramuscular injection. The
medication is ordered on a prn (as needed) basis, upon
patient request.
Prior to beginning data collection, the records of
the study participants were examined to determine
if they had received epidural analgesia during
labor or if they had used other medications or non-
pharmacological resources to relieve their pain. Partici-
pants should have been standing within at least 6 h
and no more than 24 h after labor. This time period
encompasses the period of time in which the women
could be expected to leave their bed and cease taking
medication for pain, if pain medications were used; the
24-h period refers to the acute phase of the injury (epi-
siotomy), inflammatory process and predominance of
pain. If the study participants had taken any pain
medications or used other pain-relieving methods, the
period in which it was used was controlled based on
the medical orders, thus controlling any possible inter-
ferences in pain assessment. Afterwards, a data form
was completed which included the puerpere profiles,
obstetric procedures performed, and records and data
from the labor period and the newborn for both
groups.
Two investigators were involved in data collection
for this study. They were trained to standardize the
treatment and assessments. Investigator 1 was respon-
sible for patient evaluation and assessing the pain in
all subjects. Investigator 2 applied the treatment in the
high-frequency TENS group.
Figure 2 Schematic representation of the positioning of
the electrodes on the puerpere.
A. C. R. Pitangui et al.
982 © 2012 The Authors
Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology
Functional capacity check
In order to check functional capacity, at the beginning
of the study the participants were asked about their
daily activities and whether there were any limitations
present. These activities were: sitting, ambulating, uri-
nating, bowel movements, personal hygiene, eating,
sleeping and breast-feeding.
Pain measurement
Post-episiotomy pain was assessed using an 11-point
numeric rating scale (NRS). The volunteers were
required to give a number between 0 and 10 that indi-
cated their pain intensity, where 0 indicated no pain
and 10 was the most intense pain imaginable. This tool
presents validity and reliability to measure acute and
post-surgery pain.14–16 This assessment was performed
in both groups at the following times: (i) beginning of
the study – first evaluation; (ii) after 60 min – second
evaluation; and (iii) after 120 min – third evaluation.
The NRS was employed for all three assessments. The
pain during resting and movement was measured by
the NRS; the participants were asked to both sit and
ambulate and report their level of pain during those
activities.
Since pain is a multidimensional experience, the Bra-
zilian version of the McGill Pain Questionnaire (MPQ)
was selected to measure the effect of TENS on multiple
domains of pain. The MPQ has four dimensions
(sensory, affective, evaluative and miscellaneous) rep-
resented by 20 subcategories. This study also assessed
the Pain Rating Index (PRI) and the Number of Words
Chosen (NWC) aspects of the MPQ. These pain mea-
surement tools were applied at the beginning of the
study and after 60 min.
Patients in the no treatment control group and the
TENS group were excluded from analysis of the pain
outcome if they were given any other treatment (anal-
gesic medication or other non-pharmacological
methods) during the data collection period. For ethical
reasons, the patients in the control group received con-
ventional pharmacological treatment or TENS treat-
ment at the end of study.
TENS–related questions
After the conclusion of the study, puerpere from the
TENS group were asked the following questions about
the therapeutic application: (i) What did you think
about TENS therapy? (ii) Would you use TENS again in
the future? (iii) Are you satisfied with TENS? and (iv)
Would you like to make any comments or suggestions
regarding TENS?
Data analysis
Data for the TENS high frequency and control groups
by the NRS were compared using the unpaired t-test,
and intragroup differences were analyzed using the
repeated measures anova with post-hoc Tukey. Basic,
obstetric and neonatal characteristics were compared
using the Mann–Whitney test for analyzing continuous
variables, and Pearson’s c2-test or Fisher’s exact test for
analyzing categorical variables. Data are represented as
mean ⫾SD.
In the MPQ category analysis, as a criterion to char-
acterize the pain of the experience of episiotomy in
natural childbirth, descriptors chosen by at least 33% of
study participants were established, since values equal
or higher to this percentage would be sufficient to iden-
tify the characteristics of a particular type of pain.17,18 To
analyze the PRI of the MPQ, the Wilcoxon test was used
for the intragroup analysis and the Mann–Whitney
test for the intergroup analysis. In the intergroup analy-
sis for the NWC the unpaired t-test was used and the
intragroup differences were calculated using the
paired t-test. Results for all tests were considered sig-
nificant at P<0.05. All data analyses were performed
using the Statistical Package for Social Sciences soft-
ware versiom 16.0 (SPSS, Chicago, IL, USA).
Results
Participant characteristics
Puerpere ages varied between 18 and 31 years (median
of 20.5 years). In both groups, there were no significant
statistical differences in age (P=0.369), education
(P=0.749) or color (P=0.386).
Obstetric variables
As for the gestational age, all 40 puerpere had full-term
pregnancies (median of 39 weeks’ gestation). The
median of prenatal care appointments was eight
appointments. Regarding epidural analgesia, 71.1% of
women from both groups were given an epidural. In
the TENS group, 68.4% had an epidural, while the
figure was 73.7% for the control group. No significant
difference was observed in the use of epidural analge-
sia (P=0.721), spontaneous delivery of the placenta
(P=0.547) or the presence of a companion during labor
(P=0.311).
Neonatal variables
Concerning the newborn infants, 55% were male and
the median weight was 3070 g. No significant statistical
difference was found in weight (P=0.820) or height
(P=0.799).
High-frequency TENS in post-episiotomy
© 2012 The Authors 983
Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology
Resources used postpartum
The pain relief resources used by the study participants
in the TENS group before the beginning of the study
were: diclofenac (14.3%), dipyrone (9.5%) and ice packs
(4.8%). The control group used diclofenac (10%) and
ice packs (15%). No significant difference was obser-
ved in these variables between the groups (P=0.675,
P=0.157, P=0.269, respectively).
Functional limitations
The activities that were reported by the puerpere
as causing functional limitation due to episiotomy
pain were: sitting (87.5%), walking (77.5%), personal
hygiene (55%) and sleeping (45%), followed by less
affected functions: breastfeeding (22.5%), urinating
(22.5%) and eating (5%). Regarding bowel movements,
82.5% mentioned that they had not had a bowel
movement within the studied time frame.
Pain outcomes
Numeric rating scale
The groups presented similar pain scores in the basal
level while resting (P=0.068), sitting (P=0.054) and
ambulating (P=0.334). Treatment with TENS at high
frequency significantly reduced pain intensity as mea-
sured by the NRS in resting, sitting and ambulating
activities (P<0.001), immediately after TENS and
60 min later when compared with the control group. In
intragroup analyses, when comparing the first evalua-
tion with the second evaluation, and the first evaluation
with the third evaluation, there was a significant statis-
tical difference only in the TENS group (Table 1).
McGill Pain Questionnaire
The descriptors that were chosen by at least 33% of
puerpere (and thus better describe perineal pain due to
the episiotomy) were: (i) sore, sensorial (67.5%); (ii)
hurting, sensorial (60%); (iii) discomfort, evaluation
(57.5%); (iv) annoying, affective (55%); (v) burning,
sensorial (47.5%); (vi) stinging like a needle, senso-
rial (45%); (vii) throbbing, sensorial (42.5%); and (viii)
pressure, sensorial (37.5%).
There was no significant difference in the basal
analysis for the PRI (P=0.182) or NWC (P=0.389)
scores between the TENS group and the control group.
After TENS treatment, a decrease in NWC (P<0.001)
was shown in the TENS group, as well as PRI for
the sensory, affective, evaluative, miscellaneous and
total categories (P<0.001) (Fig. 3). The control group
showed no alteration in NWC (P=0.235) and PRI for
the sensory (P=0.262), affective (P=0.834), evaluative
(P=0.750), miscellaneous (P=0.500) and total catego-
ries (P=0.429). The highest number of patients chose
words from the sensory category, and there was a
similar tendency in both groups in this selection of
words (P=0.784).
TENS–related questions
One-hundred percent of puerpere reported that they
found TENS comfortable and would use it again.
Table 1 Post-episiotomy pain intensity measured using the numeric rating scale
Evaluation activities TENS
(mean ⫾SD)
Control
(mean ⫾SD)
P-value
First evaluation
Resting 4.47 ⫾1.54 3.89 ⫾1.96 0.068
Sitting 6.21 ⫾1.84 5.00 ⫾1.91 0.054
Ambulating 5.47 ⫾2.50 4.68 ⫾2.47 0.334
Second evaluation
Resting 0.89 ⫾1.15†‡ 3.94 ⫾1.98 <0.001*
Sitting 1.78 ⫾1.61†‡ 4.73 ⫾1.96 <0.001*
Ambulating 1.68 ⫾1.70†‡ 5.05 ⫾2.36 <0.001*
Third evaluation
Resting 1.36 ⫾1.53†§ 4.10 ⫾2.18 <0.001*
Sitting 2.42 ⫾1.80†§ 5.21 ⫾2.01 <0.001*
Ambulating 2.36 ⫾2.06†§ 5.21 ⫾2.39 <0.001*
*P<0.05. Data are reported as mean ⫾SD. †Intergroup difference. ‡Intragroup difference
between the first and second evaluations. §Intragroup difference between the first and third
evaluations. Rows: analysis intergroup. Columns: analysis intragroup. Analysis intragroup –
P-value: TENS <0.001*. Control >0.05. Analysis intergroup: Unpaired t-test. Analysis intra-
group: Repeated measures anova with post-hoc Tukey. TENS, transcutaneous electrical
nerve stimulation.
A. C. R. Pitangui et al.
984 © 2012 The Authors
Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology
Regarding the use of TENS therapy for the treatment of
their pain, 50% professed to be ‘very satisfied’ and 50%
were ‘satisfied’. None of the participants chose the
items ‘little satisfied’ or ‘not satisfied’. No discomfort
or irritation was reported by the women.
Discussion
The objective of this study was to evaluate the effec-
tiveness of TENS as a perineal pain relief resource
employed in primiparous puerpere who had under-
gone an episiotomy. The data in this research suggest
that high-frequency TENS use significantly reduces
pain intensity in post-episiotomy puerpere. TENS
decreased the scores of initial pain classified as mod-
erate to weak in resting, sitting and ambulation activi-
ties, therefore producing a relevant clinical difference.
Since pain is considered to be a multidimensional
and subjective phenomenon,19,20 the implementation of
a measuring instrument to take into account of all its
varied aspects is suggested.9The NRS is considered to
be an easily understood application tool,21,22 having a
good correlation with the visual analogical scale fre-
quently used during the post-surgical period.15 Th e
MPQ is an important instrument to measure the com-
plexity of painful experiences.23
Results achieved in this study using the MPQ dem-
onstrated that the TENS group showed a reduction in
the NWC and PRI, confirming the results found in the
NRS that demonstrate the effectiveness of TENS for
post-episiotomy perineal pain.
Regarding the MPQ, both groups showed a higher
tendency towards choosing descriptors within the
sensory category, a fact that was expected by the
researchers and has also been found by other authors, as
this category has typically gathered the majority of
descriptors in previous studies.9,24
As in this study where we demonstrated the efficacy
of the use of TENS, other authors found similar results,
demonstrating the indication of its employment for
post-surgical pain.9,10,25,26 High-frequency TENS reduces
pain by interfering with transmission of the nociceptive
input at the level of the spinal cord through activation
of d-opioid and gamma-aminobutyric acid (GABA)A
receptors, subsequently reducing input through the
ascending spinothalamic tract.25,27
In order to obtain better results in the employment of
high-frequency TENS, it is fundamental to standardize
the location and positioning of electrodes, time, pulse
duration, intensity and electrical stimuli frequency8,28,29
TENS ideal intensity should be the highest intensity
capable of generating a strong paresthesia,8without
causing pain30 These recommendations were followed
in this study.
Regarding puerpere opinions, 100% of the partici-
pants who used TENS found the TENS therapy com-
fortable and reported that they would use it again. No
reports of side effects or dissatisfaction were made,
supporting the results of other studies.25
Concerning functional limitation, many authors have
found that perineal pain can cause decreased mobil-
ity2,31 and discomfort when passing feces or urine,31
have a negative impact on the woman’s ability to care
for her infant or to breastfeed,1,4,32 and may add to
mental exhaustion or depression.33 Agreeing with the
literature, in this study women also reported functional
limitations in daily activities.
Unfortunately, for ethical reasons it was not possible
to have a control group who received no treatment of
pain, as it was necessary to offer the use of a pain
resource to this group at the end of study. Hence it
was not possible to verify analgesia consumption
after TENS treatment. Furthermore, for clinical and
Figure 3 Post-episiotomy pain measured by the Pain
Rating Index (PRI) of the McGill Pain Questionnaire
(MPQ). Bars represent the average value; error bars
represent the standard deviation. Intergroup analysis
was done using the Mann–Whitney test and intragroup
analysis was done using the Wilcoxon test. †Intergroup
difference; P<0.05. *Intragroup difference between the
first and second evaluations; P<0.05. All categories of
PRI were significantly lower in the transcutaneous
electrical nerve stimulation (TENS) group after TENS
treatment when compared with the control group
(Control). 1, first evaluation; 2, second evaluation; A,
affective; E, evaluation; M, miscellaneous; S, sensory; T,
total; TAF, high frequency transcutaneous electrical
nerve stimulation.
High-frequency TENS in post-episiotomy
© 2012 The Authors 985
Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology
logistical reasons, it was impossible to know if analge-
sia was requested by the women or given under phy-
sician orders.
A limitation of the study is that, while investigators
were blinded, patients were not, for obvious reasons.A
placebo group was not included because its inclusion is
not possible in the case of TENS, as there is no placebo
equivalent for sensory stimulation.34 However, a no
treatment control group was included because its
presence is believed to be fundamental in providing
a comparison parameter to the TENS group. Possible
limitations to our study include not only the lack of a
placebo TENS group, but also the duration of the study
(a one-hour follow-up to capture the potential benefits
of intervention). Despite the results found in this study,
future research is needed to elucidate the effects and
influences of TENS on relieving post-episiotomy pain.
Inclusion of a placebo group, different parameters of
electrical waves and a longer follow-up period will
provide more information regarding the use of TENS
as a method of pain relief for women who have expe-
rienced an episiotomy in natural childbirth.
This randomized and controlled clinical study dem-
onstrated that high-frequency TENS is an effective
modality that is easily applied, low cost and is safe to use
in the control of pain in primiparous puerpere having
undergone an episiotomy, resulting in a decrease
in pain scores during resting, sitting and walking
activities right after its use and 60 min later. Therefore,
TENS is a safe and viable non-pharmacological
analgesic resource to be employed for pain relief
post-episiotomy.
Acknowledgments
The authors thank the Conselho Nacional de Desenvolvi-
mento Científico e Tecnológico (CNPq, Brazil).
Disclosure
No potential conflicts of interest have been declared.
References
1. Steen M, Cooper K, Marchant P, Griffiths-Jones M, Walker J.
A randomised controlled trial to compare the effectiveness of
ice-packs and Epifoam with cooling maternity gel pads at
alleviating postnatal perineal trauma. Midwifery 2000; 16:
48–55.
2. East CE, Sherburn M, Nagle C, Said J, Forster D. Perineal
pain following childbirth: Prevalence, effects on postnatal
recovery and analgesia usage. Midwifery 2011. doi:10.1016/
j.midw.2010.11.009.
3. Carroli G, Mignini L. Episiotomy for vaginal birth. Cochrane
Database Syst Rev 2009. doi: 10.1002/14651858.CD000081.
4. Macarthur AJ, Macarthur C. Incidence, severity, and determi-
nants of perineal pain after vaginal delivery: A prospective
cohort study. Am J Obstet Gynecol 2004; 191: 1199–1204.
5. Levitt C, Shaw E, Wong S et al. McMaster University Postpar-
tum Research Group. Systematic review of the literature on
postpartum care: Methodology and literature search results.
Birth 2004; 31: 196–202.
6. Steen M, Cooper K. A new device for the treatment of
perineal wounds. J Wound Care 1999; 8: 87–90.
7. Melzack R, Wall PD. Pain mechanisms: A new theory. Science
1965; 150: 971–978.
8. Walsh DM, Howe TE, Johnson MI, Sluka KA. Transcutaneous
electrical nerve stimulation for acute pain. Cochrane Database
Syst Rev 2009. doi: 10.1002/14651858.CD006142.
9. de Santana JM, Sluka KA, Lauretti GR. High and low fre-
quency TENS reduce postoperative pain intensity after lap-
aroscopic tubal ligation: A randomized controlled trial. Clin J
Pain 2009; 25: 12–19.
10. de Santana JM, Santana-Filho VJ, Guerra DR, Sluka KA,
Gurgel RQ, da Silva WM Jr. Hypoalgesic effect of the trans-
cutaneous electrical nerve stimulation following inguinal
herniorrhaphy: A randomized, controlled trial. J Pain 2008; 9:
623–629.
11. Bernstein SL, Bijur PE, Gallagher EJ. Relationship between
intensity and relief in patients with acute severe pain. Am J
Emerg Med 2006; 24: 162–166.
12. Cepeda MS, Africano JM, Polo R, Alcala R, Carr DB. What
decline in pain intensity is meaningful to patients with acute
pain? Pain 2003; 105: 151–157.
13. Merkel SI, Gutstein HB, Malviya S. Use of transcutaneous
electrical nerve stimulation in a young child with pain from
open perineal lesions. J Pain Symptom Manage 1999; 18:
376–381.
14. Chibnall JT, Tait RC. Pain assessment in cognitively impaired
and unimpaired older adults: A comparison of four scales.
Pain 2001; 92: 173–186.
15. DeLoach LJ, Higgins MS, Caplan AB, Stiff JL. The visual
analog scale in the immediate postoperative period: Intra-
subject variability and correlation with a numeric scale.
Anesth Analg 1998; 86: 102–106.
16. Li L, Liu X, Herr K. Postoperative pain intensity assessment:
A comparison of four scales in Chinese adults. Pain Med 2007;
8: 223–234.
17. Dubuisson D, Melzack R. Classification of clinical pain
descriptions by multiple group discriminant analysis. Exp
Neurol 1976; 51: 480–487.
18. Gagliese L, Melzack R. Age-related differences in the qualities
but not the intensity of chronic pain. Pain 2003; 104: 597–608.
19. Sloman R, Wruble AW, Rosen G, Rom M. Determination of
clinically meaningful levels of pain reduction in patients
experiencing acute postoperative pain. Pain Manag Nurs 2006;
7: 153–158.
20. Melzack R, Wall PD. Textbook of Pain, 3th edn. Edinburgh:
Churchill Livingstone, 1994.
21. Hartrick GT, Kovan JP, Shapiro S. The numeric rating scale
for clinical pain measurement: A ratio measure? Pain Pract
2003; 3: 310–316.
A. C. R. Pitangui et al.
986 © 2012 The Authors
Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology
22. Pitangui ACR, Sousa L, Ferreira CHJ, Gomes FA,
Nakano AMS. Measurement and characteristics of perineal
pain in primiparous undergoing episiotomy. Acta Paul Enferm
2009; 22: 77–82.
23. Melzack R, Torgerson WS. On the language of pain. Anesthe-
siology 1971; 34: 50–59.
24. Melzack R. The short-form McGill pain questionnaire. Pain
1987; 30: 191–197.
25. Erdogan M, Erdogan A, Erbil N, Karakaya HK, Demircan A.
Prospective, randomized, placebo-controlled study of the
effect of TENS on postthoracotomy pain and pulmonary
function. World J Surg 2005; 29: 1563–1570.
26. Platon B, Andréll P, Raner C, Rudolph M, Dvoretsky A,
Mannheimer C. High-frequency, high-intensity transcutane-
ous electrical nerve stimulation as treatment of pain after
surgical abortion. Pain 2010; 148: 114–119.
27. Maeda Y, Lisi TL, Vance CG, Sluka KA. Release of GABA and
activation of GABA(A) in the spinal cord mediates the effects
of TENS in rats. Brain Res 2007; 1136: 43–50.
28. Carroll D, Tramèr M, McQuay H, Nye B, Moore A. Ran-
domization is important in studies with pain outcomes:
Systematic review of transcutaneous electrical nerve stimula-
tion in acute postoperative pain. Br J Anaesth 1996; 77: 798–
803.
29. Chesterton LS, Foster NE, Wright CC, Baxter GD, Barlas P.
Effects of TENS frequency, intensity and stimulation site
parameter manipulation on pressure pain thresholds in
healthy human subjects. Pain 2003; 106: 73–80.
30. Sluka KA, Walsh D. Transcutaneous electrical nerve stimula-
tion: Basic science mechanisms and clinical effectiveness. J
Pain 2003; 3: 109–121.
31. Leeman LM, Rogers RG, Greulich B, Albers LL. Do unsu-
tured second-degree perineal lacerations affect postpartum
functional outcomes? J Am Board Fam Med 2007; 20: 451–457.
32. Hedayati H, Parsons J, Crowther CA. Topically applied anaes-
theics for treating perineal pain after childbirth. Cochrane
Database Syst Rev 2005. doi:10.1002/14651858.CD004223.
33. Wald A. Constipation, diarrhea and symptomatic hemor-
rhoids during pregnancy. Gastroenterol Clin North Am 2003;
32: 309–322.
34. Van der Spank JT, Cambier DC, De Paepe HM, Danneels LA,
Witvrouw EE, Beerens L. Pain relief in labor by transcutane-
ous electrical nerve stimulation (TENS). Arch Gynecol Obstet
2000; 264: 131–136.
High-frequency TENS in post-episiotomy
© 2012 The Authors 987
Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology
