A non-randomized chlinical trial The effect of pelvic floor exercises at home and electrical stimulation plus biofeedback in hospital in management of stress urinary incontinence of primiparas in short-term postpartum period

Background To investigate the effect of pelvic floor exercises at home and electrical stimulation plus biofeedback in hospital in management of stress urinary incontinence (SUI) primiparas in short-term postpartum period. Methods A total of 150 SUI primiparas at postpartum 6-8 weeks were interviewed. According to participants’ willingness and necessary coordination, the subjects were divided into 2 groups including the treatment group (n=69) and the control group (n=81). The treatment group received at-home pelvic floor muscle training(PFMT) every day and in-hospital electrical stimulation plus biofeedback therapy twice a week for consecutive 5 weeks (from 6-8 postpartum weeks to 11-13 postpartum weeks). The control group was not given pelvic floor exercise at home or in hospital. The PFM strength in the two groups was measured by specially trained personnel using digital palpation (Modified Oxford scale:0-5 grade) and surface electromyography(sEMG) in 6-8 postpartum weeks and in 11-13 postpartum weeks. For statistical analysis, t -test,Chi-square analysis and Wilcoxon test were carried out. Results The recovery rate of SUI in the treatment group was 63.8% (44/69), which was higher than that in the control group (12.3%,10/81) ( p <0.05). In the treatment group, the PFM strength was higher after PFMT than that before PFMT no matter measured by digital palpation or by sEMG ( p <0.05); but in the control group, it had no change at postpartum 6-8 weeks and at postpartum about 12 weeks ( p >0.05). Conclusion: The combination treatment of at-home PFM training and in-hospital electrical stimulation plus biofeedback PFM therapy is an effective method to manage SUI and improve PFM strength in short-time postpartum.

Pelvic floor disorders (PFDs) are common in adult women, especially in women during pregnancy and postpartum period [1] . PFDs of women mainly refer to stress urinary incontinence (SUI), pelvic organ prolapsed (POP), sexual dysfunction and fecal incontinence [2] . PDFs can negatively affect women's self-perception of their body image and life quality [3] . Many studies showed that the damage of pelvic floor muscles (PFMs) was closely related to SUI in short-time postpartum period [4][5][6] . Hence, early implementation of preventive strategies on pelvic floor muscle training (PFMT) is essential. PFMT can be carried out at home or in outpatient, which includes PFM exercise, electrical stimulation and biofeedback training. During PFMT, a lot of women are unable to contract the muscles correctly, especially at the start of the training program. Studies [7] showed that inadequate activation of muscle groups and incorrect breathing patterns were the most common mistakes when PFM exercising. It has been proved that supervised training protocol is more effective than oral instruction alone. Digital palpation and surface Electromyography (sEMG) recordings are often applied to teach PFM contraction and evaluate the effect of PFMT [8][9] .
This study investigates the therapeutic effect of at-home PFM training combined with inhospital electrical stimulation plus biofeedback therapy on Chinese primipara with SUI in the short-term postpartum period. The scale of PFM strength was examined using digital palpation and sEMG, and questionnaire survey method was carried out by specially trained personnel before and after the PFM training.

Ethical approval
The study protocol was approved by the Ethics Committee of Maternal and Child Health Hospital of Hubei Province (201301) and all included women signed written informed consent.

Selection of patients and study design
Women who had delivered in the obstetric department and visited in the pelvic floor rehabilitation center in postpartum 6-8 weeks period at the Maternal and Child Health Hospital of Hubei Province, Tongji Medical College, Huazhong University of Science and Technology from January 2016 to January 2017 were selected as research objects.
Inclusion criteria included Chinese singleton primiparas, age ranging from 20 to 35 years old, clean lochia, no obstetric complications, and no history of accepting PFMT during pregnancy and at postpartum 6-8 weeks period. Exclusion criteria included age less than 20 years old or more than 35 years old, non-Chinese nationality, multiple pregnancies, vaginitis and urinary tract infection, and mental incapacity. A total of 217 SUI primiparas at postpartum 6-8 weeks were interviewed (SUI was diagnosed by questionnaire). The PFM strength was measured by specially trained personnel using digital palpation (Modified Oxford scale:0-5 grade) and sEMG. According to participants' willingness to PFMT and through some necessary coordination, the subjects were divided into 2 groups including the treatment group and the control group. In the treatment group, at-home PFMT was given every day under the guidance of specialized medical personnel and in hospital electrical stimulation plus biofeedback therapy was given twice a week for 5 weeks from 6-8 postpartum weeks to 11-13 postpartum weeks. The control group was not given pelvic floor exercise at home or in hospital. At postpartum 11-13 weeks, the PFM strength in the two groups was measured again using digital palpation and sEMG, and SUI was diagnosed by questionnaire again. All the investigation and examination results were recorded truthfully, including patient characteristics, history, and pregnancy delivery data.
The diagnosis of SUI Diagnostic criteria [10] . SUI was diagnosed from the following four aspects. ① to test is urine routine was normal, ②to test whether there was nervous system disease, ③to test whether there were other diseases of urinary system, ④to diagnose whether the patient cannot help leaking urine during coughing, sneezing, laughing, changing position or upon sudden increase of abdominal pressure.
Determination of PFM strength using digital palpation Digital palpation [11] . PFM was determined by specialized medical personnel using digital palpation. First of all, women were told to empty the bladder and took lithotomy position. Rejection Ratio of >100 dB at 60 Hz, input impedance>100Mʊ, amplifier gain 500). a 16bit analog to digital(A/D) converter with an 500Hz anti-aliasing filter was used. The probe was inserted using a small amount of antiallergic lubricant positioned laterally in the vagina. After cleansing the skin with an alcohol swab, round self-adhesive electrodes (silver chloride) were applied to the skin over the examined muscle. On the basis of guaranteeing the patients not make visible contractions of these muscles, the next two bipolar self-adhesive electrodes were located on the right side along muscle fibers of the rectus abdominis, hip adductor muscle and gluteus maximus.
Here below is the MVC procedure, and sEMG signal was recorded during each trial (Fig 1) [12] : --a 10-second baseline sEMG recording.
--5 repeated short (quick flick) contraction with a 5-second pause between each contraction, average mean (MVC) (mean amplitude value of the active sEMG portions, which is calculated when the amplitude exceeds the threshold level predetermined as 50% between minimum and maximum amplitudes in each particular trial) is analyzed.
--5 repetitions of 10-second voluntary contractions with 10 seconds of rest in between.
--a sustained 60-second contraction. The magnitude of external forces or loading is not sufficient to initially estimate forces generated by the pelvic floor muscle. The only way to ensure correct performance of the task is to use the maximal contraction and provide verbal encourage to maintain the contraction. Therefore, the instruction "pull up and in, and squeeze around the probe as strongly as you can until you hear the command now relax" is given during the trial. The average mean of contraction of the sEMG signal is analyzed (MVC).
PFM training at home [ 4 ] When SUI women in 6-8 weeks postpartum period was diagnosed, the specialists in our department of pelvic floor center would teach them how to contract their PFM by demonstrating vaginal palpation. At first, the women were told to empty the bladder and took lithotomy position, then the specialist placed her index finger into the vaginal and told the women to lift and squeeze around the finger. For Kegel exercise at home, a sustained 5-second contraction with 10-second pause was performed as a cycle, 10 cycles as a repetition, and 10 repetitions were the amount of training for one day with supine position or upright position. Such training was regularly carried out for 5 weeks at home.
The PFMT at home was monitored by the specialists and nurses in our department through

Results
Demographic data of the treatment group and the control group A total of 217 SUI primiparas at postpartum 6-8 weeks were interviewed (SUI was diagnosed by questionnaire), excluding 2 cases with non-Chinese nationality, 3 cases of irregular vaginal bleeding, 12 cases for not cooperative with specially trained personnel and 50 cases for not come back to examine the PFM strength at postpartum 11-13 weeks.
There were 69 cases in the treatment group and 81 cases in the control group (See Fig 2: diagram flow). Through statistical comparison, it can be known that the difference was not statistically significant between the treatment group and the control group on maternal age, gestational weight gain, BMI of delivery, gestational age at birth, new baby's weight, and delivery modes (  In the control group, the PFM strength at 11-13 postpartum weeks was as weak as that at 6-8 postpartum weeks by digital palpation and sEMG (p 0.05) (Tab 4, 5)..
For both groups, there was no significant difference in PFM strength after PFMT at 6-8 postpartum weeks (p 0.05). However, the PFM strength was stronger in the treatment group than that in the control group at 11-13 postpartum week (p0.05)( Tab 4,5)..

Discussion
SUI is a common PFDs during pregnancy and postpartum [1][2][3] . Lin YH et al [15] investigated that 51.5% (446/866) had self-reported SUI during pregnancy and 12.5% (70/560) women accepting vaginal delivery and 7.2% (22/306) women accepting cesarean delivery had SUI at postpartum 12 months. Zhang G et al [16] found SUI was more likely to manifest as leakage of urine when the abdominal pressure gradually increased with the development of pregnancy weeks. The SUI prevalence was 7.5% (9/120), 22.5% (27/120), 43.3% (52/120), and 5.8% (7/100), in 34, 36, and 38 gestational weeks, and 6 weeks after delivery, respectively. Our previous research showed that the SUI rate of vaginal delivery was 6.8% (187/2749) [4] . SUI exerts a negative impact on the quality of life. How to recover from SUI as soon as possible after delivery is the focus of our research. Postdelivery SUI is correlated with the weak strength of PFM [4,5] . In our study, PFMT at home and in hospital was carried out for consecutive 5 weeks from 6-8 postpartum weeks to 11-13 postpartum weeks. Results showed that 63.8% (44/69) women could recover from SUI with accepting PFMT, and 12.3% (10/81) could recover from SUI without accepting PFMT.
This shows that short-time postpartum PFMT is effective in the treatment of SUI.
How to effectively exercise PFM strength? Arnold Kegel [17] is known as the first researcher to use PFMT in the treatment of urogynecology dysfunctions. Soon after his studies, many training protocols have been proposed [18][19] . Liu L [6] observed 72 menopausal female patients with SUI, among which 24 patients received electrical stimulation therapy combined with biofeedback for 60 days and displayed a clear improvement in their urinary incontinence, pelvic floor muscle strength, leakage times, frequency of urination, urine dynamics index. Electrical stimulation combined with biological feedback seems to bring about better clinical effects than conventional pelvic floor muscle exercises. Schmitt JJ [20] observed that patients received 4-7 sessions (1 every 2 weeks) including biofeedback plus electrical stimulation to ninety-four PFDs patients with urinary or defecatory dysfunction, pelvic pain, dyspareunia, then had a high rate of self-reported subjective success and satisfaction after PFMT by questionnaire, then PFMT should be considered a nonsurgical treatment option in patient with PFDs. Wang QJ [21]  More than one method has been adopted to obtain a comprehensive understanding of PFM function [22][23] . However, it is difficult to evaluate PFM function and there is no gold standard for such evaluation [24] . Digital vaginal palpation and sEMG evaluation are two common methods to evaluate the strength of PFM. Yang X et al [8] assessed 1,380 parturients at 6-8 postpartum weeks by using both vaginal palpation and sEMG. Results showed that the contraction variables of EMG had a significant correlation between them and sEMG was also correlated with SUI. In our study, digital vaginal palpation was used to make a general investigation on the PFM strength based on a larger sample size [4,9] .   Chi-square test is used