Authors: Carrie Ng (*Department of Pediatrics, Emory University School of Medicine; †Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Grace Promer (*Department of Pediatrics, Emory University School of Medicine; †Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Brent Troy (‡Department of Pediatrics, The University of Texas at Austin Dell Medical School, Austin, TX), Abby Lewis (*Department of Pediatrics, Emory University School of Medicine; †Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Ashley Hoyos (†Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Laura Covelo (†Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Olivia Carlson (†Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Naina R. Reddy (†Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Calvin Abdallah (†Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Avnee Sarnaik (†Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Jeffrey Ling (†Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Andrew Jergel (§Pediatric Biostatistics Core, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA.), Claudia R. Morris (*Department of Pediatrics, Emory University School of Medicine; †Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA), Tal E. Berkowitz (*Department of Pediatrics, Emory University School of Medicine; †Department of Pediatric Emergency Medicine, Children’s Healthcare of Atlanta, Atlanta, GA)
Categories: Article, bladder catheterization, ultrasound, point-of-care ultrasound
Source: Pediatric emergency care
Authors: Carrie Ng, Grace Promer, Brent Troy, Abby Lewis, Ashley Hoyos, Laura Covelo, Olivia Carlson, Naina R. Reddy, Calvin Abdallah, Avnee Sarnaik, Jeffrey Ling, Andrew Jergel, Claudia R. Morris, Tal E. Berkowitz
Bladder catheterization (BC) is a routine procedure, but unsuccessful attempts due to inadequate bladder volume are common and stressful for children and caregivers. Physician-performed bladder point-of-care ultrasound (POCUS) improves BC success rates, but the effect of nurse-performed POCUS remains understudied.
We randomized children under 24 months of age to receive either nurse-performed POCUS before BC or standard blind BC in the pediatric emergency department to compare dry catheterization rates. A simplified POCUS technique using a single bladder measurement was employed to enhance efficiency and feasibility for nursing staff. We also compared caregiver satisfaction and procedural time between groups. Statistical comparisons used the Pearson χ^2^ test for categorical variables and the Wilcoxon rank sum test for continuous variables. A P value of < 0.05 was considered statistically significant. Univariate logistic regression estimated the odds of outcomes with POCUS versus standard care.
In the POCUS group, the dry catheterization rate was 5% compared with 17% in the standard group (odds ratio = 0.24, 95% CI = [0.09, 0.72]), indicating fewer dry BCs in the POCUS group. Caregivers of children in the POCUS group reported higher satisfaction (P = 0.02). There was no significant difference in the time from BC orders to initial BC attempt between groups.
Nurse-performed POCUS before BC reduces dry BCs and improves caregiver satisfaction without causing procedural delays. Incorporating nurse-performed POCUS into standard BC workflows may enhance patient care.
Bladder catheterization (BC) is a common procedure in the pediatric emergency department (PED) to obtain urine samples from children who are not toilet-trained. It serves as a vital diagnostic tool for evaluating urinary tract infections and other urinary tract abnormalities.^1-5^ However, BC can be challenging, particularly in young children, and may fail due to factors such as difficult anatomy or inadequate bladder volume.^6,7^
Dry BCs, resulting from insufficient bladder volume, often require multiple attempts. These additional attempts cause distress for both children and caregivers while increasing the risk of complications such as pain, urethral trauma, and infection.^8-10^ Previous studies have shown that bladder point-of-care ultrasound (POCUS) performed before BC improves success rates and caregiver satisfaction.^11-15^ However, many of these studies primarily involved physicians performing the ultrasound.
Baumann et al^14^ performed a randomized trial with nurses performing the POCUS, similar to this study. A small, single-center trial as well, they demonstrated the feasibility of nurse-performed POCUS. In most PEDs, nurses, rather than physicians, typically perform BCs. To optimize efficiency and reduce physician workload, it may be more practical for nurses to perform both POCUS and BC. In their trial, nurses performed volumetric bladder measurements, different from the modified one-measurement bladder ultrasound that our nurses performed to increase ease of use.^14^ In addition, their study demonstrated a longer time to catheterization compared with standard care without POCUS.^14^ Given the lack of literature on the efficacy of nurse-performed bladder ultrasound in improving BC success rates in children,^14^ this study aimed to assess the impact of nurse-performed POCUS on catheterization success, caregiver satisfaction, and procedural time.
This study was approved by our Institutional Review Board. Enrollment began in February 2023 and concluded in February 2024 at our 330-bed children’s hospital in the southeastern United States. Research coordinators approached families about participation after confirming with the primary physicians. Written informed consent was obtained from a parent or legal guardian of all participants.
This randomized controlled trial used convenience sampling. Participants were assigned to 1 of 2 groups based on the calendar those enrolled on even days underwent nurse-performed POCUS, while those enrolled on odd days received standard BC.
Children ≤ 24 months of age presenting to our PED and requiring BC were eligible. Exclusions included known urogenital abnormalities, emergent BC needs, indwelling urinary catheters, caregiver objection, or if the treating physicians deemed the child unsuitable for the study.
POCUS and BC were the interventions. Patients in the standard group underwent BC according to routine practice, with nurses initiating the BC as soon as feasible.
Nurses received training from one of the study investigators, either a pediatric emergency medicine (PEM) physician or a third-year medical student who had been trained by a PEM physician. The training consisted of a one-on-one, in-person session that included an overview of the study’s objectives, requirements, and protocol, followed by orientation to the ultrasound machine and the completion of a supervised scan. The entire training session lasted ~20 minutes. Upon successful completion of the supervised scan, nurses were approved to participate in the study.
The bladder POCUS examination involved applying gel to the patient’s lower abdomen just above the pubic symphysis while the patient was in the supine position. A curvilinear or phased array probe was used to examine the bladder in either the sagittal or transverse plane. If the bladder measured at least 2 cm in any direction, then the nurse would proceed with a BC. If the bladder measured < 2 cm or if the child urinated during the POCUS examination, then the bladder was rechecked at 30-minute intervals until sufficient urine volume was identified. The 2 cm threshold was established to correlate with an approximate volume of 2 mL of urine, which our hospital’s laboratory deemed the minimum volume sufficient for urinalysis and culture. This approach allowed for more efficient training and minimized errors. Unlike previous studies, which require multiple bladder measurements to calculate the bladder volume,^12-15^ our intervention relies on a previously described POCUS technique that uses a single bladder measurement, with 2 cm in any direction considered adequate.^11^ This technique allows for simplified training, maximizing efficiency, and minimizing potential error.
If the physician caring for the patient was concerned about significant dehydration or the nurse or parent reported recent urination, the physician and nurse would discuss whether BC should be delayed until the patient’s hydration status was optimized.
Data were recorded using Research Electronic Data Capture (REDCap)^16^ and Microsoft Teams. REDCap captured the following age, sex, date when the BC was performed, initial BC attempt volume of urine collected ( ≥ or < 2 mL), the name and years of experience of the nurse/paramedic/technician performing the BC, time of BC order, time of BC attempt, and reasons for failure if applicable. Each entry was assigned a unique study ID number to ensure confidentiality and streamline analysis. Separate data sheets housed within Microsoft Teams contained age, sex, date, medical record numbers, corresponding study ID numbers, the individual responsible for patient enrollment, reasons for exclusion if applicable, and caregiver satisfaction survey responses.
Our primary objective was to compare dry catheterization rates between the nurse-performed POCUS and standard groups. We hypothesized that using POCUS to confirm adequate urine in the bladder before BC would decrease the number of dry BCs.
Secondary objectives included comparing caregiver satisfaction scores on a 4-point Likert scale between the POCUS group and the standard group and determining if POCUS increased procedural time. Caregivers were given a 4-question satisfaction survey relating to the BC procedure, rated on a 4-point Likert scale, immediately following the initial BC attempt. The survey was administered by study staff, independent of the nurse or health care provider involved in the process. The survey is included in Figure 1. We hypothesized that satisfaction would be higher in the POCUS group and that the use of POCUS would not significantly increase the BC time.
The primary outcome was the rate of dry catheterizations. Secondary outcomes included the overall success rate of catheterization, defined as obtaining at least 2 mL of urine within the first try, with failures counted regardless of whether they were due to dry catheterization or other reasons. In addition, caregiver satisfaction scores and the time from the BC order to the first BC attempt were also included as secondary outcomes.
Patient allocation was based on the date of the BC order, with even calendar days assigned to POCUS and odd days to standard BC. Only nurses who had volunteered to participate in the study received bladder POCUS training. Enrollment in the POCUS arm only occurred when both an enrollment staff member and a POCUS-trained nurse were available on an even calendar day.
Due to the nature of POCUS, the study was not blinded.
The originally planned sample size was 500 participants (250 per group), based on detecting a 10% absolute difference between groups with 80% power and a 2-sided α of 0.05. Three hundred and thirty-nine individuals were assessed for eligibility but only 180 were eligible and analyzed (Fig. 2). While attempts were made to reach the original sample size calculation, enrollment concluded at 180 participants, due to financial restraints. We report odds ratios with 95% CIs to reflect the magnitude and precision of the observed differences.
The analysis compared various parameters between groups, including overall success rates, overall failure rates, and failures due to dry BCs, reported as total observations and proportions. Continuous variables, such as the time from BC order to the initial BC attempt, were summarized using medians and interquartile ranges. Statistical comparisons between groups were conducted using the Pearson χ^2^ test for categorical variables and the Wilcoxon rank sum test for continuous variables. A P value of < 0.05 was considered statistically significant.
Univariate logistic regression was employed to provide standardized effect sizes, for interpretation and to estimate the odds of our primary and secondary outcomes with the primary intervention POCUS versus the standard. In addition, due to differences in sex between the POCUS and standard care groups, exploratory multivariable logistic regression models were performed with sex as a potential confounder. Results are reported as odds ratios (ORs), and 95% CIs were provided to reflect the magnitude and precision of observed differences in the absence of an adequately powered sample. All data cleaning and statistical analyses were conducted using R Statistical Software (v4.2.1; R Core Team, 2022).
A total of 339 patients were assessed for eligibility, and 207 were randomized, with 102 allocated to POCUS (85 analyzed) and 105 allocated to standard BC (95 analyzed). See Figure 2 for the participant flow diagram.
Three participants from the POCUS group were excluded from the analysis, as they underwent BC despite presenting with < 2 cm of urine observed on bladder POCUS. In addition, 6 participants were excluded from the analysis due to missing data in REDCap, 2 from the POCUS group and 4 from the standard group. Five participants filled out an incorrect survey, so their survey responses were excluded from the total analysis to maintain consistency and accuracy in data interpretation.
Patient demographics and years of nursing experience are summarized in Table 1. Both study groups exhibited similar demographic profiles with comparable median participant age and nurse experience. However, sex distribution differed between the groups, with 49% females in the POCUS group and 60% females in the standard group (P = 0.045).
In the POCUS group, 4/85 (4.7%) of participants experienced dry BCs, compared with 16/95 (16.8%) in the standard group (P = 0.009, Table 2). Overall, 74/85 (87%) of participants in the POCUS group had successful procedures, compared with 73/95 (76.8%) in the standard group, but did not reach statistical significance (P = 0.077). In addition to dry BC, the reasons that contributed to the overall rate of failure in both groups included patient urination during BC, difficulties in locating the urethral orifice, and the inability to pass the catheter.
There was no difference between the median time from BC orders to the initial BC attempt in the POCUS group compared with the standard BC group. The median time in the POCUS arm was 34 minutes (IQR: 24, 53) compared with 32 minutes (IQR: 19, 47.5) in the standard arm (P = 0.123).
Caregiver satisfaction was higher in the POCUS group compared with the standard group (Fig. 3). POCUS caregivers more frequently reported being “Very Satisfied”^4^ in every category, most notably in overall experience (P = 0.02) and perceived time satisfaction (P = 0.005).
Our study demonstrates that nurse-performed POCUS can significantly reduce the rate of dry BCs in children under 2 years of age. However, there were still 4 patients with dry BCs in the POCUS group. All 4 of these patients had soiled diapers before undergoing the POCUS exam. It is possible that these patients urinated between the POCUS exam and the BC, but we could not conclusively determine whether urination occurred during that interval. As a result, nurse-performed POCUS significantly reduced dry catheterizations but did not eliminate them.
Although POCUS demonstrated a higher overall success rate, this difference did not reach statistical significance (P = 0.077), likely due to confounding factors such as catheterization failures unrelated to POCUS and early termination of the study. We attempted to control for confounders through randomization. The POCUS group had more catheterization successes, and while the difference did not reach statistical significance, this was likely due to factors unrelated to the POCUS itself, including patient urination during BC, difficulty locating the urethral orifice, and the inability to advance the catheter. Despite not reaching statistical significance, the results trended in favor of POCUS.
While preprogrammed and portable ultrasound devices such as BladderScan (Diagnostic Ultrasound Corporation) have been developed to automatically estimate bladder volume, these devices have been shown to be inaccurate, especially in young children, making them less suitable for the PED setting.^17-19^ In De Gennaro et al,^18^ the investigators evaluated the reliability of BladderScan BVI 2500 in pediatric patients and found that bladder scanners were less accurate in estimating bladder volumes compared with conventional ultrasound measurements. De Gennaro et al^18^ chose ultrasonography as a comparison because it is a validated method for evaluating bladder volume, and they wanted to avoid catheterization of normal, healthy pediatric volunteers for ethical reasons. The inaccuracies were particularly pronounced in children < 36 months with BladderScan overestimating by a mean of 28%, a mean overestimation of 20% in children between 36 to 83 months, and 5% in children > 83 to 192 months.^18^ Prentice et al^17^ is another study that compared bladder volume measurements obtained via bedside ultrasound (Zonare Ultra version 4.8 or Sonosite M-turbo) and bladder scanners (BMI 9400, Verathon Inc.) in adults in an intensive care unit setting.^17^
The findings revealed significant discrepancies between the 2 methods, with bladder scanners often overestimating bladder volumes secondary to factors such as ascites and underestimating bladder volumes by 450 mL in patients with suspected indwelling catheters. In contrast, ultrasound measurements were more consistent and closely aligned with actual urine volumes. These findings suggest that bladder scanners may not consistently provide reliable bladder volume measurements in certain patient populations, particularly in children. Collectively, these studies underscore the limitations of bladder scanners and support the use of POCUS as a more dependable option. POCUS, with its ability to provide real-time, precise imaging, along with its versatility across various patient populations and clinical settings, makes it a valuable tool for enhancing procedural success rates and improving patient outcomes. Notably, caregiver satisfaction was markedly higher in the POCUS group, confirming our secondary hypothesis. This increase in satisfaction was achieved without a significant increase in procedural time.
Our study outcomes were consistent with prior studies comparing POCUS to standard BC, demonstrating the effectiveness of ultrasound-assisted BC in pediatric populations.^11-15^ While prior studies predominantly focused on physician-performed ultrasound,^12,13,15^ our study extends this knowledge by demonstrating the feasibility and efficacy of nurse-performed POCUS in reducing dry BCs. This reinforces the importance of expanding the scope of ultrasound use to nonphysician personnel, such as nurses, to optimize BC outcomes in pediatric emergency care. One prior study by Baumann et al^14^ did use nurses to perform the POCUS as well as the catheterization. Given that it was a small study, recreation of these findings is imperative with further study, but our study offered one methodical advantage as well as one further improved outcome. In the Baumann study, only 3 nurses were trained and needed to learn to perform volumetric measurement of the patients’ bladders, a somewhat cumbersome process.^14^ Our simplified measurement, initially detailed in Witt et al,^11^ allowed us to train more nurses and allowed a quicker approach to performance of the POCUS. Their study from 2005, while calling it volumetric measurement, used a single transverse bladder measurement of 2 cm as a cutoff to perform catheterization, but they did not specify who performed the POCUS.^11^ While there is a theoretical risk of decreased accuracy, the limited approach was demonstrated in Witt et al,^11^ as well as in this study, to be sufficient for ensuring the small amount of urine needed is available. Possibly related to this, we did not see the same delay in catheterization as did the aforementioned study.^11,14^
This study was conducted at a single academic pediatric children’s hospital, which may affect generalizability. POCUS is also operator-dependent, and this variability may affect the reproducibility of this study. In addition, as an unfunded project with limited resources, this study was concluded earlier than expected, and some missing data points led to the exclusion of several patients. Nonetheless, while the study did not reach its prespecified sample size target, the observed 12% difference between groups was statistically significant and clinically meaningful.
An additional limitation of the study was the absence of recorded time intervals between the bladder POCUS and bladder catheterization. This interval likely varied due to factors such as the availability of catheterization supplies, preparation time for the procedure, and staffing to assist with patient positioning. During this period, spontaneous voiding or continued bladder filling may have occurred. Consequently, unmeasured changes in bladder volume could have affected the accuracy of our comparisons and study findings.
Another limitation is that we did not collect data on the total number of catheterization attempts per patient. Success in this study was defined solely by the outcome of the first attempt. Therefore, we are unable to assess whether the use of POCUS influenced overall success rates beyond the initial BC attempt.
Augmenting BC with nurse-performed POCUS has the potential to improve procedural outcomes and caregiver satisfaction not only in PEDs but also across various health care settings where BC is routinely performed, including general emergency departments and inpatient units. The standardized protocol for POCUS implementation outlined in our study can be adapted for further study in diverse health care settings.
Similarly, while our study focused on children aged ≤ 24 months, the principles of nurse-performed POCUS can be extrapolated to older pediatric populations and even adult patients requiring BC upon further study. The anatomic and physiological considerations may vary across different age groups, but the fundamental goal of reducing dry BC is still relevant. Future research could explore the efficacy of nurse-performed POCUS in older pediatric populations to further validate its utility across a broader spectrum of patients.
In addition, our study has implications for who can perform POCUS. This simplified measurement can be taught to and performed by other nonphysician staff, such as paramedics or technicians, who already perform BCs, potentially improving patient flow in PEDs. However, the performance of POCUS may be limited in some institutions due to existing scope-of-work restrictions. Expanding these roles to include POCUS could be warranted based on the evidence supporting its use and the potential benefits for young children requiring BC.
One of the notable strengths of nurse-performed POCUS is its potential applicability in resource-limited settings, where access to specialized health care providers, such as physicians or sonographers, may be limited. By empowering nurses with the skills and training necessary to perform POCUS-assisted BC, health care facilities in underserved areas can improve the quality and efficiency of BC procedures without relying on external expertise.
To maximize the generalizability of our study findings, it is crucial to consider the practical aspects of implementing nurse-performed POCUS in different health care contexts. Factors such as training protocols, equipment availability, workflow coordination, and institutional support play pivotal roles in the successful adoption of POCUS-assisted BC practices. Future research and implementation initiatives should address these considerations to ensure the seamless integration of nurse-performed POCUS into routine clinical practice across various health care settings.
In summary, while our study provides evidence for the efficacy of nurse-performed POCUS in reducing dry BCs and improving caregiver satisfaction in pediatric emergency care settings, its broader generalizability potentially extends to diverse health care settings, patient populations, and resource contexts.
Our approach seeks to balance the need for rapid, easily adoptable training with the goal of maintaining accuracy. While volumetric measurement may offer increased precision and could further reduce dry catheterizations, the Baumann study^14^—limited by the involvement of only 3 nurses—highlights the challenges of broadly training staff in this more complex technique. In contrast, we successfully trained a larger cohort of nurses and aim to extend this training model to paramedics and technicians using a simplified, single-measurement approach. This streamlined method, while less exact, offers a practical advantage in scalability. Although a 2 cm measurement does not equate precisely to 2 mL, our findings suggest it reliably indicates at least 2 mL of bladder volume, aligning with our goal of achieving the minimum intervention necessary to obtain a urine sample.
By adopting nurse-performed POCUS as a standard tool in BC procedures, health care providers can improve outcomes and patient experience. We advocate for further research in diverse clinical populations to validate and expand upon these findings.