A prospective, controlled, multicenter clinical trial was conducted, with random allocation of women to two groups, between the months of November 2016 and May 2018.
Population selection
The reference population was women who gave birth in the following hospitals situated in south-east Spain: San Juan de la Cruz in Ubeda (Jaen), San Agustin in Linares (Jaen), Jaen University Hospital Complex, University Hospital Virgen de las Nieves (Granada), and Hospital Torrecardenas in Almeria.
The inclusion criteria were: Age > 18 years, primiparous, singleton and eutocic delivery, second-degree perineal tear or an episiotomy as part of labor, and a newborn weight between 2500 g and 4000 g. The following exclusion criteria were used: language barrier, problems related to the pelvic floor prior to labor (prolapse, incontinence, vulva varices, etc.), dyspareunia or sexual dysfunction, hemorrhoids perceived as uncomfortable or painful, or women who did not wish to participate or did not sign the informed consent.
To estimate the sample size, the main outcome was taken into account: pain. Sample size estimation was based on the next assumptions: a statistical power of 80%, an α level of 5%, a 1:1 allocation between the intervention group and the reference group, a frequency of pain of 60.4% in women with interrupted sutures [9], and a priori reduction of pain of 50% with continuous sutures. With these assumptions 54 women would be required in each group: Assuming a loss of 20%, the sample size needed was 67 women in each group. Figure 1.
Intervention
Two types of sutures were used for the perineal injury using two different techniques: Group A received continuous sutures and Group B had interrupted sutures placed. The two techniques and sutures are described in more detail in Additional file 1. The women were allocated to a treatment group using a computer-generated random numbers table. The generated sequence was placed in individual opaque envelopes that were opened when a woman met the inclusion criteria.
The health personnel that placed the sutures had previously taken a training course on continuous suture technique and had at least 1 year of experience in this technique. Additionally, this person had a minimum of 5 years of experience in attending deliveries and, therefore, also in the suturing of perineal injuries. The sutures were placed by ten trained midwives. Around 5% [1] of the midwives in Torrecardenas, 10% [2] in the Hospital Complex of Jaen, 12% [3] in Granada, and 20% [2] of the midwives in Ubeda and Linares participated.
Data collection
To evaluate the perception of pain experienced by women during labor the verbal rating scale (VRS) was used [15].
Data was collected on sociodemographic variables, type of perineal injury (tear of second-degree or episiotomy), type of suture used, time spent placing suture, number of suture packets used, complications, severity of pain, type of pain, need for analgesia, wound condition, care performed, urinary and/or fecal incontinence, start of sexual relations, and start of physical activity. Data was also collected on the start of labor (spontaneous or induced) and type of delivery, medication during dilation, type of analgesia used, gestational week, duration of the first stage of labor, second stage labor and delivery, as well as data regarding the newborn.
Information was gathered by midwives who interviewed the women in the delivery room, providing them with an informed consent form. The rest of the data were obtained from the clinical history, maternal record book and via follow-up phone calls. The women were blinded to the suture technique used.
Follow-up
The women were followed-up as follows:
Day of childbirth: in the postpartum period, the midwife collected data on the type of delivery, need for epidural analgesia, duration of dilation, stage two of labor, delivery, type of perineal trauma, time used to place suture, number of suture packets, wound complications, newborn weight and the Apgar score at 1 min and at 5 min. After the suture was placed, they assessed pain on the pain scale and assessed the wound.
Follow-up after delivery was done at 2 h, 24 h, 15 days and 3 months. Pain, need for analgesia, wound condition, sphincter incontinence, and the start of sexual relations were assessed (15 days and 3 months).
Data analysis
First of all, randomized groups were compared regarding variables which could influence the outcomes: statistically significant imbalances were found for marital status and attendance to a health education course during pregnancy. Associations between binary outcomes (e.g., pain - yes/no, incontinence - yes/no) was ascertained by computing odds ratios (OR) and their 95% confidence intervals (CI); the variables imbalanced after randomization were adjusted for using a non-conditional logistic regression analysis. Normality was checked in continuous variables (e.g., pain assessed by verbal rating scale, time to restart sexual intercourse). In the comparison of continuous outcomes between the two groups the t-test was applied in univariate analyses, and the analysis of covariance to adjust for the two imbalanced baseline variables.
Ethics approval
The study was carried out following the precepts included in the Belmont report and the Declaration of Helsinki (updated at the Brazil Assembly in 2013) for biomedical research.
Both the design and the development of the work conform to the standards of good clinical practice (CPMP / ICH / 135/95, July 2002 revision of the European Medicines Agency -EMeA).
Ethical approval was obtained from the Ethics Committees of the hospitals participating in the study: Comité de Ética de la Investigación del Hospital Universitario Virgen de las Nieves de Granada (Ethics Committee for Research of the University Hospital Virgen de las Nieves in Granada), Comité de Ética de la Investigación del Hospital Torrecardenas (Ethics Committee for Research of the Torrecardenas Hospital in Almeria), Comité de Ética de la Investigación del Complejo Hospitalario Universitario de Jaén; (Ethics Committee for Research of the University Hospital of Jaen) Comité de Ética de la Investigación del Hospital de Úbeda (Ethics Committee for Research of the Ubeda Hospital) and Comité de Ética de la Investigación del Hospital de Linares (Ethics Committee for Research of the Linares Hospital).
Written informed consent was obtained from all the women before recruitment into the study. Informed consent was obtained from the women participating in the study and we also followed the protocols established by the respective health centres for accessing data from medical records to carry out this type of research with the purpose of publication/disclosure to the scientific community.
(ClinicalTrials.gov Identifier: NCT03825211, restrospectively registered)