high-frequency tens in post-episiotomy pain relief in primiparous puerpere: a randomized, controlled...

High-frequency TENS in post-episiotomy pain relief inprimiparous puerpere: A randomized, controlled trialjog_1824 980..987

Ana Carolina Rodarti Pitangui1,3, Ligia de Sousa1, Flávia Azevedo Gomes1,Cristine Homsi Jorge Ferreira2 and Ana Márcia Spanó Nakano1

1College of Nursing and 2Department of Biomechanics, Medicine and Rehabilitation of the Locomotor Apparatus, Faculty ofMedicine, 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) asa 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-pointnumeric rating scale was performed in three separate evaluations (at the beginning of the study, after 60 minand after 120 min). The McGill pain questionnaire was employed at the beginning and 60 min later. TENS with100 Hz frequency and 75 ms pulse for 60 min was employed without causing any pain. Four electrodes wareplaced 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 statisticaldifference in pain reduction in the TENS group, while the control group showed no alteration in the level ofdiscomfort. Hence, high-frequency TENS treatment significantly reduced pain intensity immediately after itsuse and 60 min later.Conclusion: TENS is a safe and viable non-pharmacological analgesic resource to be employed for pain reliefpost-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 oneof the most common causes of maternal morbidity inthe post-childbirth period.1,2 Women with an epi-siotomy have experienced greater pain and may besubjected to greater blood loss, hematomas, infections,dehiscence, sexual dysfunction, vaginal prolapse and

rectovaginal fistula in comparison to other types ofperineal trauma.3 In addition, these injuries can affectmany activities, such as walking, sitting, sleeping,urinary and intestinal movements, self-care, care of thenewborn, the efficiency and ease of lactation, sleep andappetite.1,4

Recently, some researchers have carried out studieswith 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: [email protected] 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.

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doi:10.1111/j.1447-0756.2011.01824.x J. Obstet. Gynaecol. Res. Vol. 38, No. 7: 980–987, July 2012

980 © 2012 The AuthorsJournal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology

are capable of mitigating the pain associated with anepisiotomy; however, this subject is incipiently andinfrequently approached in the literature. Both phar-macological and non-pharmacological methods havebeen employed as treatment for this discomfort.2

Medication therapy consists of the use of non-hormonal oral analgesics and anti-inflammatoryagents that are applied to the injured area;1,5 non-pharmacological resources commonly include the useof hot and cold compresses and vaginal washes.1,5

However, there are few studies capable of supportingthe effectiveness of non-pharmacological techniques,and the observations that follow them are frequentlysupported 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 electricalimpulses through the skin to control the pain.7,8

Although studies have demonstrated the effective-ness of TENS in countless surgical procedures,9,10 noprevious study has attempted to investigate the effect ofTENS on post-episiotomy pain using local applicationin the perineal area. Hence, the objective of this studywas to evaluate the effectiveness of high-frequencyTENS as a pain relief resource employed in primiparouspuerpere who had experienced natural childbirth withan episiotomy.

Patients and MethodsParticipants

This was a controlled, randomized clinical study. Fortyprimiparous puerpere in a Brazilian maternity wardwho had experienced a spontaneous vaginal deliverywith an episiotomy were randomly selected into twogroups: high-frequency TENS (n = 20) versus no treat-ment control (n = 20). All participants voluntarilysigned a Free and Informed Consent Form. The studywas approved by the Research Ethics Committee of theNursing School of Ribeirão Preto in the University ofSan Paulo, Brazil.

The volunteers were randomly placed in the active(TENS) group or the no treatment control group usinga computer-generated randomization sequence. Ran-domization occurred in the order in which participantswere enrolled in the study according to the computer-generated randomization list prepared prior to the startof the study. A blocking randomization was pro-grammed to generate a sequence of allocation to ensurethat there was a close balance of the number of subjectsin each group throughout the study. The women wererandomized into the active and the no treatmentgroups with a 1:1 ratio. The trial design is presented inFigure 1.

Sample size calculations were previously deter-mined in a pilot study with 15 puerpere. Reductions in

Figure 1 Trial design. TAF, highfrequency 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 981Journal of Obstetrics and Gynaecology Research © 2012 Japan Society of Obstetrics and Gynecology

pain scores following the intervention were used as themeasurement parameter. A reduction of 1.3 points11,12

in the 11-point numeric rating scale was considered tobe clinically relevant with a standard deviation of 1.47and 1.25 for the TENS group and control group, respec-tively. An a = 0.01 and power = 90% (b = 0.1) required asample 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 oftime and space; (v) post-vaginal spontaneous delivery;(vi) experienced an episiotomy with stitches; (vii) pre-senting pain in the episiotomy area; and (viii) absenceof any genitourinary pathology. Exclusion criteriawere: (i) contraindications to TENS, such as openwounds; (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) morbidobesity; and (v) instrumental delivery (i.e. use offorceps).

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 theepisiotomy site (Fig. 2). The region corresponds tothe pudendal and genitofemoral nerves that supplythe perineal area. TENS was applied with 100 Hzfrequency and 75 ms pulse for 60 min.13 The increasein the electrical impulse intensity was guided by theparticipants. They were instructed that the intensityshould result in a strong numbing sensation, but withno muscle contraction. The TENS appliance was cali-brated at the beginning of data collection by a digitaloscilloscope.

Procedures

The institution’s routine protocols include limitedepisiotomy use. When required, episiotomies are per-formed using a mediolateral incision with local anes-thesia. During labor, the patients can receive epiduralanalgesia and in the postpartum period they can receivemedications and ice packs. The medications used are

dipyrone (metamizole) taken orally or intravenouslyand diclofenac (a non-steroidal anti-inflammatorydrug) taken orally or by intramuscular injection. Themedication is ordered on a prn (as needed) basis, uponpatient request.

Prior to beginning data collection, the records ofthe study participants were examined to determineif they had received epidural analgesia duringlabor 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 hand no more than 24 h after labor. This time periodencompasses the period of time in which the womencould be expected to leave their bed and cease takingmedication for pain, if pain medications were used; the24-h period refers to the acute phase of the injury (epi-siotomy), inflammatory process and predominance ofpain. If the study participants had taken any painmedications or used other pain-relieving methods, theperiod in which it was used was controlled based onthe medical orders, thus controlling any possible inter-ferences in pain assessment. Afterwards, a data formwas completed which included the puerpere profiles,obstetric procedures performed, and records and datafrom the labor period and the newborn for bothgroups.

Two investigators were involved in data collectionfor this study. They were trained to standardize thetreatment and assessments. Investigator 1 was respon-sible for patient evaluation and assessing the pain inall subjects. Investigator 2 applied the treatment in thehigh-frequency TENS group.

Figure 2 Schematic representation of the positioning ofthe electrodes on the puerpere.

A. C. R. Pitangui et al.


Functional capacity check

In order to check functional capacity, at the beginningof the study the participants were asked about theirdaily activities and whether there were any limitationspresent. 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-pointnumeric rating scale (NRS). The volunteers wererequired to give a number between 0 and 10 that indi-cated their pain intensity, where 0 indicated no painand 10 was the most intense pain imaginable. This toolpresents validity and reliability to measure acute andpost-surgery pain.14–16 This assessment was performedin both groups at the following times: (i) beginning ofthe study – first evaluation; (ii) after 60 min – secondevaluation; and (iii) after 120 min – third evaluation.The NRS was employed for all three assessments. Thepain during resting and movement was measured bythe NRS; the participants were asked to both sit andambulate and report their level of pain during thoseactivities.

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 multipledomains of pain. The MPQ has four dimensions(sensory, affective, evaluative and miscellaneous) rep-resented by 20 subcategories. This study also assessedthe Pain Rating Index (PRI) and the Number of WordsChosen (NWC) aspects of the MPQ. These pain mea-surement tools were applied at the beginning of thestudy and after 60 min.

Patients in the no treatment control group and theTENS group were excluded from analysis of the painoutcome if they were given any other treatment (anal-gesic medication or other non-pharmacologicalmethods) during the data collection period. For ethicalreasons, 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 theTENS group were asked the following questions aboutthe therapeutic application: (i) What did you thinkabout TENS therapy? (ii) Would you use TENS again inthe future? (iii) Are you satisfied with TENS? and (iv)Would you like to make any comments or suggestionsregarding TENS?

Data analysis

Data for the TENS high frequency and control groupsby the NRS were compared using the unpaired t-test,and intragroup differences were analyzed using therepeated measures anova with post-hoc Tukey. Basic,obstetric and neonatal characteristics were comparedusing the Mann–Whitney test for analyzing continuousvariables, and Pearson’s c2-test or Fisher’s exact test foranalyzing categorical variables. Data are represented asmean � SD.

In the MPQ category analysis, as a criterion to char-acterize the pain of the experience of episiotomy innatural childbirth, descriptors chosen by at least 33% ofstudy participants were established, since values equalor higher to this percentage would be sufficient to iden-tify the characteristics of a particular type of pain.17,18 Toanalyze the PRI of the MPQ, the Wilcoxon test was usedfor the intragroup analysis and the Mann–Whitneytest for the intergroup analysis. In the intergroup analy-sis for the NWC the unpaired t-test was used and theintragroup differences were calculated using thepaired t-test. Results for all tests were considered sig-nificant at P < 0.05. All data analyses were performedusing the Statistical Package for Social Sciences soft-ware versiom 16.0 (SPSS, Chicago, IL, USA).

ResultsParticipant characteristics

Puerpere ages varied between 18 and 31 years (medianof 20.5 years). In both groups, there were no significantstatistical 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-termpregnancies (median of 39 weeks’ gestation). Themedian of prenatal care appointments was eightappointments. Regarding epidural analgesia, 71.1% ofwomen from both groups were given an epidural. Inthe TENS group, 68.4% had an epidural, while thefigure was 73.7% for the control group. No significantdifference 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 andthe median weight was 3070 g. No significant statisticaldifference was found in weight (P = 0.820) or height(P = 0.799).



Resources used postpartum

The pain relief resources used by the study participantsin the TENS group before the beginning of the studywere: diclofenac (14.3%), dipyrone (9.5%) and ice packs(4.8%). The control group used diclofenac (10%) andice 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 puerpereas causing functional limitation due to episiotomypain were: sitting (87.5%), walking (77.5%), personalhygiene (55%) and sleeping (45%), followed by lessaffected functions: breastfeeding (22.5%), urinating(22.5%) and eating (5%). Regarding bowel movements,82.5% mentioned that they had not had a bowelmovement within the studied time frame.

Pain outcomes

Numeric rating scale

The groups presented similar pain scores in the basallevel while resting (P = 0.068), sitting (P = 0.054) andambulating (P = 0.334). Treatment with TENS at highfrequency significantly reduced pain intensity as mea-sured by the NRS in resting, sitting and ambulatingactivities (P < 0.001), immediately after TENS and60 min later when compared with the control group. Inintragroup 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% ofpuerpere (and thus better describe perineal pain due tothe 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 basalanalysis 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 forthe sensory, affective, evaluative, miscellaneous andtotal categories (P < 0.001) (Fig. 3). The control groupshowed no alteration in NWC (P = 0.235) and PRI forthe 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 chosewords from the sensory category, and there was asimilar tendency in both groups in this selection ofwords (P = 0.784).

TENS–related questions

One-hundred percent of puerpere reported that theyfound 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 evaluationResting 4.47 � 1.54 3.89 � 1.96 0.068Sitting 6.21 � 1.84 5.00 � 1.91 0.054Ambulating 5.47 � 2.50 4.68 � 2.47 0.334

Second evaluationResting 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 evaluationResting 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 differencebetween the first and second evaluations. §Intragroup difference between the first and thirdevaluations. 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 electricalnerve stimulation.



Regarding the use of TENS therapy for the treatment oftheir pain, 50% professed to be ‘very satisfied’ and 50%were ‘satisfied’. None of the participants chose theitems ‘little satisfied’ or ‘not satisfied’. No discomfortor 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 resourceemployed in primiparous puerpere who had under-gone an episiotomy. The data in this research suggestthat high-frequency TENS use significantly reducespain intensity in post-episiotomy puerpere. TENSdecreased 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 multidimensionaland subjective phenomenon,19,20 the implementation ofa measuring instrument to take into account of all itsvaried aspects is suggested.9 The NRS is considered tobe 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 TheMPQ 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 inthe NWC and PRI, confirming the results found in theNRS that demonstrate the effectiveness of TENS forpost-episiotomy perineal pain.

Regarding the MPQ, both groups showed a highertendency towards choosing descriptors within thesensory category, a fact that was expected by theresearchers and has also been found by other authors, asthis category has typically gathered the majority ofdescriptors in previous studies.9,24

As in this study where we demonstrated the efficacyof the use of TENS, other authors found similar results,demonstrating the indication of its employment forpost-surgical pain.9,10,25,26 High-frequency TENS reducespain by interfering with transmission of the nociceptiveinput at the level of the spinal cord through activationof d-opioid and gamma-aminobutyric acid (GABA)A

receptors, subsequently reducing input through theascending spinothalamic tract.25,27

In order to obtain better results in the employment ofhigh-frequency TENS, it is fundamental to standardizethe location and positioning of electrodes, time, pulseduration, intensity and electrical stimuli frequency8,28,29

TENS ideal intensity should be the highest intensitycapable of generating a strong paresthesia,8 withoutcausing pain30 These recommendations were followedin 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. Noreports of side effects or dissatisfaction were made,supporting the results of other studies.25

Concerning functional limitation, many authors havefound 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 carefor her infant or to breastfeed,1,4,32 and may add tomental exhaustion or depression.33 Agreeing with theliterature, in this study women also reported functionallimitations in daily activities.

Unfortunately, for ethical reasons it was not possibleto have a control group who received no treatment ofpain, as it was necessary to offer the use of a painresource to this group at the end of study. Hence itwas not possible to verify analgesia consumptionafter TENS treatment. Furthermore, for clinical and

Figure 3 Post-episiotomy pain measured by the PainRating Index (PRI) of the McGill Pain Questionnaire(MPQ). Bars represent the average value; error barsrepresent the standard deviation. Intergroup analysiswas done using the Mann–Whitney test and intragroupanalysis was done using the Wilcoxon test. †Intergroupdifference; P < 0.05. *Intragroup difference between thefirst and second evaluations; P < 0.05. All categories ofPRI were significantly lower in the transcutaneouselectrical nerve stimulation (TENS) group after TENStreatment 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 electricalnerve stimulation.



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 investigatorswere blinded, patients were not, for obvious reasons. Aplacebo group was not included because its inclusion isnot possible in the case of TENS, as there is no placeboequivalent for sensory stimulation.34 However, a notreatment control group was included because itspresence is believed to be fundamental in providinga comparison parameter to the TENS group. Possiblelimitations to our study include not only the lack of aplacebo TENS group, but also the duration of the study(a one-hour follow-up to capture the potential benefitsof intervention). Despite the results found in this study,future research is needed to elucidate the effects andinfluences of TENS on relieving post-episiotomy pain.Inclusion of a placebo group, different parameters ofelectrical waves and a longer follow-up period willprovide more information regarding the use of TENSas 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 effectivemodality that is easily applied, low cost and is safe to usein the control of pain in primiparous puerpere havingundergone an episiotomy, resulting in a decreasein pain scores during resting, sitting and walkingactivities right after its use and 60 min later. Therefore,TENS is a safe and viable non-pharmacologicalanalgesic resource to be employed for pain reliefpost-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.

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