This trial was approved by the Medical Ethics Committee of University Malaya Medical Centre (reference number: 2019330–7272 on 04/07/2019) and registered with ISRCTN (https://doi.org/10.1186/ISRCTN17787339 on 17/07/2019). The trial was performed in accordance with International Conference on Harmonization – Guidelines for Good Clinical Practice (ICH-GCP) and Declaration of Helsinki. Informed consents were obtained from all participants.
We sought in our labor ward, nulliparas (no prior delivery beyond 20 weeks gestation) in labor (at least three contractions in 10 minutes, cervical dilatation within the last 2 hours of 4 to 8 cm and ruptured membrane but without evidence of second stage) who had the urge to micturate or a palpable bladder and ultrasound scan bladder volume > 300 ml, aged > 18 years old with a singleton live fetus in cephalic presentation for trial participation. An adult functional bladder can comfortably hold between 300 and 400 ml [12]. Wall pressure of 5–15 mmHg creates a sensation of bladder fullness while 30 mmHg and beyond is painful [13]. For this trial a filled bladder that warrants voiding is defined as the urge to micturate or a palpable bladder and ultrasound bladder volume > 300 ml [14]. Women with known bladder dysfunction, recurrent antenatal urinary tract infections, lower segment uterine fibroid, on neuraxial analgesia and prior bedpan or urine catheter use during labor were excluded. Eligible women were approached, verbally informed and provided with the participant information sheet by the investigator (WKC). Written informed consents were obtained from all participants. Relevant demographic and clinical data were recorded in the Case Report Form.
Pre and postvoid ultrasound for bladder volume was performed (solely by investigator WKC) using a 3.5 MHz convex transducer with the participant in semi-recumbent position. Bladder measurements were performed in two planes (transverse and sagittal images) in between contractions. For transverse image, the transducer is positioned horizontally along the long axis of the bladder, and adjusted until the maximum transverse section is found and the maximum transverse width measured (horizontal diameter). For the sagittal image, the transducer is rotated 90-degree into the sagittal plane, position adjusted until the maximum sagittal section is obtained and sagittal depth and height were then measured. Sonographic measurements were recorded for sagittal height, sagittal depth and transverse width of the bladder (i.e., h, d and w). Using the prolate ellipsoid method [15], volume = 0.52 x h x d x w [16].
Prior to randomization women were asked on their preferred method to urinate using bedpan, mobilize to toilet, catheterization or no preference. Participants were randomized to micturition by mobilizing to toilet or using bedpan by opening the lowest numbered, sealed and opaque envelope that remained. The randomization sequence was computer generated in blocks of 4 or 8 using random.org by investigator (PCT) who was not involved with recruitment.
Participants randomized to mobilizing to toilet were disconnected from medical devices and can choose to go to the toilet with a companion (birth partner or the midwife) or by themselves with the door closed, for up to 10 min to micturate on a standard sitting toilet. The voided urine was collected into a disposable plastic bag that was hold firmly under the toilet lid. The voided urine volume was measured after decanting to a measuring jug. Participants in the bedpan arm was provided with the bedpan and be in any position that was comfortable to her (lying or sitting on the bed) for up to 10 min to micturate. The voided volume was measured after decanting to a measuring jug.
Primary outcome of satisfactory micturition is defined as residual urine volume < 150 ml by ultrasound. A residual bladder volume ≥ 150 ml typically defines covert postpartum urinary retention [17, 18]. Participants who were not able to micturate, or if their residual urine volume ≥ 150 ml, were asked to cross-over to the opposite intervention for another attempt. If after attempting both methods and residual urine volume was > 250 ml, a standard “in and out” bladder catheterization was offered and performed under an aseptic technique.
Immediately after completion of their micturition attempt, participants provided a 5-grade Likert’s scale response of their satisfaction with their allocated intervention and stated their preferred bladder voiding method to “if you have to pass urine again during labor, what would you prefer?”. Labor and neonatal outcomes were retrieved from participants’ charts. Prespecified secondary outcomes were in-out catheterization, duration of the second stage of labor, mode of delivery, estimated delivery blood loss and maternal satisfaction after allocated intervention prior to any crossover.
Participants, investigator (WKC) who performed the ultrasound and care providers were not masked to the interventions as it was impractical due to its obvious nature.
As there was no direct pilot data available, sample size calculation was based on in-out catheterization rates of 19% vs 54% in recovery room among postoperative patients (early mobilization vs bedpan) [19] as surrogate outcome to represent unsatisfactory micturition of this study. We applied a more conservative difference of 25% vs 50%, alpha 0.05, power 80%, 1:1 randomization and Chi-square test, 58 participants were needed in each arm (N = 116) using the PS: Power and Sample Size Calculation [20].
Data were entered into SPSS (Version 23, IBM, SPSS Statistics). Student t test was applied for means with normally distributed continuous data, Mann-Whitney U test for non-normally distributed data or ordinal data, Chi-square test for categorical data across trial arms and paired t test for continuous data within trial arms. Two-sided P values were reported and p < 0.05 was regarded as significant. Analysis was based on intention-to-treat.
