Study design, setting, and participants
This single-center, single-blinded, stratified randomized controlled trial was conducted at the Siriraj Lactation Clinic of the Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand during February 2019 to July 2020. Siriraj Hospital is Thailand’s largest national tertiary referral center with approximately 8,000 deliveries per year. Our center’s lactation clinic, the Siriraj Lactation Clinic, attends to approximately 2,000 cases of breastfeeding associated problems per year.
Eligible participants were lactating women who presented at the Siriraj Lactation Clinic with plugged milk duct that had developed within 72 h of presentation. Women who had been previously treated with antibiotics, who had received breast massage elsewhere, who had surgery on the ipsilateral breast, or who had mastitis or breast abscess were excluded. Study participants were stratified according to the widest part of the mass, measured by a caliper, (the widest part of the largest mass if several masses were present) to more than or equal to 5 cm or less than 5 cm. This stratification was based on findings from the study of lactational breast abscess that the abscess size of more than 5 cm was a risk factor for failure of treatment by needle aspiration [6]. This study complied with all of the principles set forth in the 1964 Declaration of Helsinki and all of its subsequent amendments, and written informed consent was obtained from all study participants. The protocol for this study protocol was approved by the Siriraj Institutional Review Board (SIRB) (COA no. SI065/2019), and was retrospectively registered in the Thai Clinical Trials Registry, which is one of the primary registries of the WHO Registry Network. The study registration number is TCTR20190925001.
Breast massage procedure
The affected breast was covered with a wet warm towel (except for the nipple area) for 10 min, and breastmilk was removed by electrical pump (Symphony®; Medela AG, Baar, Switzerland) or by breastfeeding the participant’s baby for 30 min. Two registered nurses were committed to a specific breast massage technique throughout the entire study, NM for IBM and ST for TBM. Before starting the massage, the study participant was in the supine position with the head elevated at a 45o angle. The nurse performing the massage was position beside the patient’s head. The massage pressure would reach skin and superficial fascia levels and the underlying muscles or bone should never be palpated [7]. The pressure was generated from the massager’s hands, arms, and shoulders, not from the massager’s body weight by leaning toward the participants during the massage. The massagers took great care to adjust the pressure according to the participant’s comfort, which were continuously assessed by the massagers.
A 30-min session of assigned breast massage was given by the assigned nurse in a private room away from other nurses working in the clinic. To blind the outcome assessor, both study massage nurses were in the room with the participant at the same time, so the assessor did not know which type of massage the patient received during the session. Participants could not be blinded to the massage technique they received.
Traditional breast massage (TBM) [2]
Step 1: The massager places her hands on the affected breast and gently massages around the breast for 5 rounds to relax the participant.
Step 2: Starting from the base of the breast, use the middle 3 fingers to lightly press and massage in a circular motion. Move around to cover the entire breast from its base ascending toward the nipple for five minutes.
Step 3: Manually express breast milk until slow flow is achieved, followed by a repeat of steps 1–3 until the end of the 30-min session.
Integrated breast massage (IBM) technique (Fig. 1)
Step 1 to 3 of the IBM technique was described by Ma. Ines Av. Fernandez, an executive director of Arugaan Foundation, Philippines, in her presentation at the 4th National Breastfeeding Conference in Thailand in 2013 [5]. From step 1 to step 3, took approximately 5 min.
Step 1: Butterfly stroke – Apply continuous pressure to the affected breast while moving along the base of the breast from the medial side to the axillary area. Then repeat the same motion at the upper half of the breast.
Step 2: Fingertip circle – With the fingers of one hand, lightly press and massage the breast in a circular motion while moving around the areola and supporting under the breast with the other hand.
Step 3: Diamond stroke – The breast is positioned between the fingers and thumbs of both hands (resembling a diamond shape), followed by both hands moving toward each other and toward the areola. Alternating between hands, press the breast with the palmar side of the 2nd to 5th fingers, and then release (resembling patting on the breast). With the tips of the 2nd to 5th fingers, press into the breast gently, then move both hands away from each other with an action that is similar to scratching. Repeat the same motions around the breast toward the axillary area.
Step 4: Promotion of milk duct dilatation and augmentation of milk drainage from areas with plugged milk ducts – Gently squeeze and roll the areolar area between the thumb and forefinger. Gently fix and squeeze the breast mass with the non-dominant hand while the dominant hand manually expresses breast milk by gently compressing the areola and nipple between the thumb and index finger.
Follow-up schedule
Participants underwent pain assessment, mass measurement, and one session of breast massage every time they visited the clinic. After the first visit, participants were followed-up daily until the breast mass was no longer palpable, and then they were interviewed by telephone at 3–5 days after the last visit. Study women were advised to return to the clinic if a breast mass reemerged or if experiencing breast pain. All participants were instructed to regularly express breast milk by hand, breast pump, or breastfeeding every three hours (total of 8 times per day), and to maintain a daily record of milk expression time and frequency. Ibuprofen and/or acetaminophen was prescribed for pain control.
Outcome measurements and operational definitions
At recruitment, a single assigned nurse who was not involved with the trial and who was blinded to the intervention measured the breast mass with a caliper at its widest x and y axes. Mass size in square centimeters (cm2) was calculated by multiplying the x-axis distance by the y-axis distance. Because changes in mass diameters in x and y axes after the interventions may not be proportional, the multiplication product of both diameters should better represent changes in mass size. Before massage, participants were asked to rate their breast pain according to a 0-to-10 numerical rating scale (NRS), with zero indicating no pain, and a 10 indicating the worst possible pain. At the end of each breast massage session, participants were asked to once again rate their level of breast pain. The same assigned nurse then remeasured the size of the breast mass. At each visit, the participants were examined for clinical signs of mastitis or breast abscess, inquired for analgesics use, and compliance in breast milk drainage.
Plugged milk duct was diagnosed clinically by the development of acute painful breast masses (localized milk stasis), which could be accompanied by mild redness of the covering skin and low-grade fever (≤ 38.4 °C) [3]. Breast abscess was distinguished from plugged milk ducts by the presence of higher-grade fever (> 38.4 °C), fluctuation of the mass upon palpation, and severe pain upon gentle palpation [3]. If a clinical diagnosis of breast abscess was uncertain, diagnostic breast ultrasound would be performed to determine the diagnosis. Complete resolution of plugged milk duct was defined as no recurrent breast mass in the same area within the follow-up period of the study. Recurrence that developed after the end of the study follow-up period was considered a new episode of plugged milk duct.
Sample size calculation and statistical analysis
The sample size was calculated based on a survival time design using data from our pilot study. The preliminary results showed a median time to resolution of four and two days after treatment with TBM and IBM, respectively. The specified accrual time and additional follow-up time after the accrual interval was 60 days and five days, respectively. Forty-two participants were required in each arm to obtain detection power of 80%, type I error of 0.05, and to compensate for an estimated possible 20% drop-out rate [8].
Block of 4 randomization was performed by a statistician using the nQuery software program (Statistical Solutions Ltd, Cork, Ireland). Sealed opaque envelopes were used to conceal the study arm assignment of each enrolled study patient. Participants were to be withdrawn from the trial if mastitis or breast abscess developed at any point during the study. As a rescue treatment, participants could be switched to the other arm at any time if the reduction in mass size was less than 20% after receiving the assigned breast massage technique at that visit.
Descriptive statistics were used to summarize the demographic and clinical characteristics of study women. Categorical data were presented as number and percentage and were compared using chi-square test or Fisher’s exact test, depending on the size of the sample. Normally and non-normally distributed continuous data were demonstrated as mean plus/minus standard deviation (SD) and median and interquartile range (IQR), respectively. These continuous data were compared using Student’s t-test and Mann–Whitney U test, respectively. After Kaplan–Meier survival curve analysis, differences in plugged milk duct resolution time were analyzed by log rank test. All analyses were performed in an intention-to-treat manner. SPSS software version 18.0 (SPSS, Inc., Chicago, IL, USA) was used for statistical analysis, and Microsoft Excel version 2019 (Microsoft Corporation, Redmond, WA, USA) was used for graphical presentation. A p—value less than 0.05 was considered statistically significant for all tests.
