Detecting postoperative urinary retention with an ultrasound scanner

Preoperative Postvoid Residual Is Not Predictive of Postoperative Urinary Retention in Primary Total Joint Arthroplasty Patients

Background

Postoperative urinary retention is a common complication after total hip and knee arthroplasty. Postvoid residual (PVR) scanning is a noninvasive method commonly used to evaluate this complication. Preoperatively increased PVR (PrePVR) has been suggested as a risk factor for postoperative catheterization. The aim of this study was to prospectively assess the importance of PrePVR and its relationship with urinary catheter placement, urology consult, and length of stay postoperatively.

Methods

Data was prospectively and consecutively collected at a single institution. All patients were bladder scanned preoperatively to collect PrePVR and subsequently scanned on postoperative days zero and one to collect Postoperative PVR. Chart review was performed to determine the number of straight catheterizations, Foley placement, urology consult and length of stay as well as patient demographics.

Results

Ninety-four consecutive patients were included in this study. There was a significantly increased postoperative PVR as compared to PrePVR (48.0 mL vs 21.0 mL; P < .0001). A PrePVR >50 mL was not associated with a significant difference in PVR between before and after surgery (P = .13); length of stay (P = .08); need for straight catheterization (P = .11); postoperative Foley placement (P = 1.0); or urology consult (P = 1.0). The only significant risk factor identified for postoperative Foley catheter placement was age (77.7 vs 64.2; P = .02).

Conclusions

PrePVR >50 mL was not an accurate predictor of postoperative urinary retention after total joint arthroplasty. PVR significantly increased in all patients. Male sex and increasing age were associated with large increases in PVR postoperatively and an increased risk of catheterization.

Routine Use of Bladder Scans After Primary Total Joint Arthroplasty is Not Necessary: Results of a Protocol Change

BACKGROUND

Postoperative urinary retention is a common concern after total joint arthroplasty (TJA) and can cause discomfort, incontinence and, if left untreated, myogenic changes to the bladder. However, overdiagnosis of postoperative urinary retention by bladder scans may lead to unnecessary interventions and delayed discharges. The purpose of this study was to compare the safety of two bladder management protocols following TJA.

METHODS

From January 3, 2022 to April 29, 2022, 519 consecutive patients operated on by thirteen surgeons underwent routine postoperative bladder scanning (standard protocol). From February 28, 2022 to April 29, 2022, a new protocol was introduced by three surgeons in 209 consecutive patients using a specific algorithm (selective protocol) so that only symptomatic patients had bladder scans. The primary outcome of interest was catheterization rate. Chi-square and Students t-tests were used for analyses. There were 37.7% of patients in the selective group who received scans.

RESULTS

Times to catheterization, readmissions, emergency department visits, and straight catheterization rates (15.0 versus 14.8% P = .999) were similar. More scans in the selective group resulted in intervention (39.2 versus 15.0%, P < .001). Prevoid volumes were higher in the selective protocol (608 versus 448 mL, P < .001). Postvoid volumes were similar (233 versus 223 mL, P = .497). There was one readmission for a urinary tract infection in the standard group and no urinary-related readmissions in the selective group.

CONCLUSION

The selective protocol had a higher rate of same day discharge, fewer bladder scans, and did not lead to increased rates of urinary-related complications. These findings suggest that selective bladder scanning for symptomatic patients can be safely instituted for TJA patients.

Impact of early postoperative indwelling urinary catheter removal: A systematic review

BACKGROUND

Indwelling urinary catheters (IDUCs) are associated with complications and early removal is therefore essential. Currently, it is unknown what the effect of a specific removal time is and what the consequences of this removal time are.

RESEARCH QUESTION

To present an overview of the available evidence to determine the effects of three postoperative IDUC removal times (after a certain number of hours, at a specific time of day and flexible removal time) on the development of complications in hospital.

METHODS

PubMed, Medline, Embase, Emcare and Cochrane Central Register of Controlled Trials were searched till 6 June, 2021. Studies were included that described the effect of the removal time in relation to re-catheterisation, urinary tract infections (UTIs), ambulation time, time of first voiding and hospital stay. The quality of the studies was assessed with the Newcastle-Ottawa Scale and the Cochrane Effective Practice and Organisation of Care. A narrative descriptive analysis was performed. PRISMA guidelines were followed in reporting this review.

RESULTS

Twenty studies were included from which 18 compared removal after a number of hours, 1 reported on a specific removal time and 1 reported on both topics. The results were contradicting regarding the hypothesis that later removal increases the incidence of UTIs. Earlier removal does not lead to a higher re-catheterisation rate while immediate removal is beneficial for reducing the time to first ambulation and shortening the hospital stay. Studies reporting on specific removal times did not find differences in outcomes. No study addressed flexible removal time.

CONCLUSIONS

There is inconclusive evidence that earlier removal results in less UTIs, despite the incidence of UTIs increasing if the IDUC is removed ≥24 h. Immediate or after 1-2 day(s) removal does not lead to higher re-catheterisation rates while immediate removal results in earlier ambulation and shorter length of hospital stay.

IMPLICATIONS OF KEY FINDINGS

Nurses should focus on early IDUC removal while being aware of urinary retention.

Predictors of postoperative urinary retention after posterior spinal fusion for adolescent idiopathic scoliosis

PURPOSE

To determine predictors for postoperative urinary retention in adolescents undergoing posterior spinal fusion for idiopathic scoliosis. Postoperative urinary retention affects almost every third adolescent after spinal fusion for idiopathic scoliosis. There are limited data regarding the risk factors of postoperative urinary retention in this patient group.

METHODS

A retrospective study with prospectively collected urinary retention data from paediatric spine register with 159 consecutive patients (114 females, mean age 15.6 years, range 10-21 years) undergoing pedicle screw instrumentation for adolescent idiopathic scoliosis at a university hospital between May 2010 and April 2020. Postoperative urinary retention was defined as an inability to void after catheter removal and documented residual over 300 mL as confirmed using an ultrasound or by catheterization.

RESULTS

Postoperative urinary retention was diagnosed in 33% (53 of 159) of the patients during hospital stay. Opioid amount on the day of catheter removal (OR 6.74 [95% CI: 2.47, 18.36], p < 0.001), male gender (OR 2.26 [95% CI: 1.01, 5.05], p = 0.048), and increasing weight (OR 1.04 [95% CI: 1.01, 1.07], p = 0.014) were associated with postoperative urinary retention. Mean opioid consumption on the day of catheter removal was 0.81 mg/kg (95% CI: 0.66, 0.96) in the retention group vs 0.57 mg/kg (95% CI: 0.51, 0.64) in the non-retention group, p < 0.001.

CONCLUSIONS

Higher total opioid consumption, opioid amount on the day of catheter removal, higher weight, and male gender increases the risk of postoperative urinary retention in adolescents with idiopathic scoliosis undergoing posterior spinal fusion.

Portable Ultrasound Research System for Use in Automated Bladder Monitoring with Machine-Learning-Based Segmentation

We developed a new mobile ultrasound device for long-term and automated bladder monitoring without user interaction consisting of 32 transmit and receive electronics as well as a 32-element phased array 3 MHz transducer. The device architecture is based on data digitization and rapid transfer to a consumer electronics device (e.g., a tablet) for signal reconstruction (e.g., by means of plane wave compounding algorithms) and further image processing. All reconstruction algorithms are implemented in the GPU, allowing real-time reconstruction and imaging. The system and the beamforming algorithms were evaluated with respect to the imaging performance on standard sonographical phantoms (CIRS multipurpose ultrasound phantom) by analyzing the resolution, the SNR and the CNR. Furthermore, ML-based segmentation algorithms were developed and assessed with respect to their ability to reliably segment human bladders with different filling levels. A corresponding CNN was trained with 253 B-mode data sets and 20 B-mode images were evaluated. The quantitative and qualitative results of the bladder segmentation are presented and compared to the ground truth obtained by manual segmentation.

Preventive effects of tamsulosin for postoperative urinary retention after lower limb arthroplasty: A randomized controlled study

PURPOSE

This prospective, randomized, controlled study investigated the use of tamsulosin, a selective alpha-blocker, as a prophylactic medication to prevent postoperative urinary retention (POUR) following lower limb arthroplasty.

MATERIALS AND METHODS

The criterion for diagnosing POUR was used a postoperative bladder volume over 400 mL with incomplete emptying. Patients who underwent primary total hip or knee arthroplasty were randomly assigned at a 1:1 ratio to tamsulosin treatment and non-treatment groups at a single center from September 2018 to November 2018. The treatment group received 0.2 mg of tamsulosin orally once at night for 3 days starting on postoperative day 1. During this 3-day period, an indwelling Foley catheter was maintained. The incidence of POUR according to tamsulosin treatment following lower limb arthroplasty was the primary outcome.

RESULTS

In total, 100 patients were enrolled, of whom 5 discontinued participation. POUR was diagnosed in 20 of the remaining 95 patients (21.1%). The treatment group contained 48 patients, of whom 6 (12.5%) developed POUR, whereas POUR occurred in the 14 of the 47 patients (29.8%) in the non-treatment group. Tamsulosin treatment reduced the risk of POUR by two-thirds (odds ratio [OR], 0.337; 95% confidence interval [CI], 0.117-0.971; p=0.044). The risk reduction associated with tamsulosin treatment remained robust post-adjustment for potential covariates (OR, 0.250; 95% CI, 0.069-0.905; p=0.038).

CONCLUSIONS

Tamsulosin administration immediately after lower limb arthroplasty reduced the incidence of urinary retention and diminished the need for long-term catheterization.

Strategies for the removal of short-term indwelling urethral catheters in adults

BACKGROUND

Urinary catheterisation is a common procedure, with approximately 15% to 25% of all people admitted to hospital receiving short-term (14 days or less) indwelling urethral catheterisation at some point during their care. However, the use of urinary catheters is associated with an increased risk of developing urinary tract infection. Catheter-associated urinary tract infection (CAUTI) is one of the most common hospital-acquired infections. It is estimated that around 20% of hospital-acquired bacteraemias arise from the urinary tract and are associated with mortality of around 10%. This is an update of a Cochrane Review first published in 2005 and last published in 2007.

OBJECTIVES

To assess the effects of strategies for removing short-term (14 days or less) indwelling catheters in adults.

SEARCH METHODS

We searched the Cochrane Incontinence Specialised Register, which contains trials identified from CENTRAL, MEDLINE, MEDLINE In-Process, MEDLINE Epub Ahead of Print, CINAHL, ClinicalTrials.gov, WHO ICTRP, and handsearching of journals and conference proceedings (searched 17 March 2020), and reference lists of relevant articles.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) and quasi-RCTs that evaluated the effectiveness of practices undertaken for the removal of short-term indwelling urethral catheters in adults for any reason in any setting.

DATA COLLECTION AND ANALYSIS

Two review authors performed abstract and full-text screening of all relevant articles. At least two review authors independently performed risk of bias assessment, data abstraction and GRADE assessment.

MAIN RESULTS

We included 99 trials involving 12,241 participants. We judged the majority of trials to be at low or unclear risk of selection and detection bias, with a high risk of performance bias. We also deemed most trials to be at low risk of attrition and reporting bias. None of the trials reported on quality of life. The majority of participants across the trials had undergone some form of surgical procedure. Thirteen trials involving 1506 participants compared the removal of short-term indwelling urethral catheters at one time of day (early morning removal group between 6 am to 7 am) versus another (late night removal group between 10 pm to midnight). Catheter removal late at night may slightly reduce the risk of requiring recatheterisation compared with early morning (RR 0.71, 95% CI 0.53 to 0.96; 10 RCTs, 1920 participants; low-certainty evidence). We are uncertain if there is any difference between early morning and late night removal in the risk of developing symptomatic CAUTI (RR 1.00, 95% CI 0.61 to 1.63; 1 RCT, 41 participants; very low-certainty evidence). We are uncertain whether the time of day makes a difference to the risk of dysuria (RR 2.20; 95% CI 0.70 to 6.86; 1 RCT, 170 participants; low-certainty evidence). Sixty-eight trials involving 9247 participants compared shorter versus longer durations of catheterisation. Shorter durations may increase the risk of requiring recatheterisation compared with longer durations (RR 1.81, 95% CI 1.35 to 2.41; 44 trials, 5870 participants; low-certainty evidence), but probably reduce the risk of symptomatic CAUTI (RR 0.52, 95% CI 0.45 to 0.61; 41 RCTs, 5759 participants; moderate-certainty evidence) and may reduce the risk of dysuria (RR 0.42, 95% CI 0.20 to 0.88; 7 RCTs; 1398 participants; low-certainty evidence). Seven trials involving 714 participants compared policies of clamping catheters versus free drainage. There may be little to no difference between clamping and free drainage in terms of the risk of requiring recatheterisation (RR 0.82, 95% CI 0.55 to 1.21; 5 RCTs; 569 participants; low-certainty evidence). We are uncertain if there is any difference in the risk of symptomatic CAUTI (RR 0.99, 95% CI 0.60 to 1.63; 2 RCTs, 267 participants; very low-certainty evidence) or dysuria (RR 0.84, 95% CI 0.46 to 1.54; 1 trial, 79 participants; very low-certainty evidence). Three trials involving 402 participants compared the use of prophylactic alpha blockers versus no intervention or placebo. We are uncertain if prophylactic alpha blockers before catheter removal has any effect on the risk of requiring recatheterisation (RR 1.18, 95% CI 0.58 to 2.42; 2 RCTs, 184 participants; very low-certainty evidence) or risk of symptomatic CAUTI (RR 0.20, 95% CI 0.01 to 4.06; 1 trial, 94 participants; very low-certainty evidence). None of the included trials investigating prophylactic alpha blockers reported the number of participants with dysuria.

AUTHORS' CONCLUSIONS

There is some evidence to suggest the removal of indwelling urethral catheters late at night rather than early in the morning may reduce the number of people who require recatheterisation. It appears that catheter removal after shorter compared to longer durations probably reduces the risk of symptomatic CAUTI and may reduce the risk of dysuria. However, it may lead to more people requiring recatheterisation. The other evidence relating to the risk of symptomatic CAUTI and dysuria is too uncertain to allow us to draw any conclusions. Due to the low certainty of the majority of the evidence presented here, the results of further research are likely to change our findings and to have a further impact on clinical practice. This systematic review has highlighted the need for a standardised set of core outcomes, which should be measured and reported by all future trials comparing strategies for the removal of short-term urinary catheters. Future trials should also study the effects of short-term indwelling urethral catheter removal on non-surgical patients.

Choosing the Right Catheter for Pediatric Procedures: Patient Considerations and Preference

Determining the need for bladder decompression and urinary diversion in the perioperative pediatric surgical patient can cause a clinical conundrum for the surgical team. Add in the several different types of urinary diversion devices possible, and the various materials associated therein and the process can suddenly seem unnecessarily daunting given the lack of concise recommendations and broad consensus. The decision to divert urine, though seemingly trivial, is associated with inherent risks. Managing and mitigating certain risks are best approached through proper education, selection, and technique. We provide a broad overview of pediatric catheter selection, indications, and pitfalls to streamline the process so that energy and attention can best be focused on the planned intervention at hand.

Accuracy of Measuring Bladder Volumes With Ultrasound and Bladder Scanning

BACKGROUND

Removal of urinary catheters depends on accurate noninvasive measurements of bladder volume. Patients with acute kidney injury often have low bladder volumes/ascites, possibly causing measurement inaccuracy.

OBJECTIVE

To evaluate the accuracy of bladder volumes measured with bladder scanning and 2-dimensional ultrasound (US) compared with urinary catheterization among different types of clinicians.

METHODS

Prospective correlational descriptive study of 73 adult critical care patients with low urine output receiving hemodialysis or unable to void. Bladder volumes were independently measured by (1) a physician and an advanced practice registered nurse using US, (2) an advanced practice registered nurse and a bedside nurse using bladder scanning, and (3) urinary catheterization (cath). Bland-Altman and χ2 analyses were conducted.

RESULTS

Mean (SD) cath volume was 171.7 (269.7) mL (range, 0-1100 mL). Abdominal fluid was observed in 28% of patients. Bias was -1.3 mL for US vs cath and 3.3 mL for bladder scanning vs cath. For patients with abdominal fluid and cath volume less than 150 mL, decisions to not catheterize patients were accurate more often when based on US measurements (97%-100%) than when based on bladder scanning measurements (86%-89%; P = .02). In patients with cath volume of 300 mL or more, decisions to catheterize patients were accurate more often when based on bladder scanning measurements (94%-100%) than when based on horizontal US measurements (50%-56%; P = .001).

CONCLUSIONS

Bladder volume can be measured accurately with bladder scanning or US, but abdominal fluid remains a confounding factor limiting accuracy of bladder scanning.

Urinary Bladder Test Device to Integrate Basic Ultrasound Training for Nurses

Ultrasound is a useful tool for integrating clinical assessment with a bedside reliable imaging technique, but it requires adequate training. Ultrasonographic training involves examination performed on human models, in which many pathologic findings are not always readily available for the trainee to observe. The possibility of creating test objects that reproduce pathologic images allows the provision of training courses with those elements that are not always available. Our aims were to describe how to create a urinary bladder test object and to test its image quality and usefulness. Thus, we compared computed volume with the actual filling volume for five different devices to assess their reliability in volume estimation. Moreover, we evaluated the image quality and teaching utility using a 5-point Likert-type questionnaire among a group of learners. Computed bladder volume had excellent correlation with actual filling volume (p < 0.001, R² = 0.9874). Trainees judged the ultrasound exploration realistic and considered the device useful in understanding ultrasound images and improving ultrasound skills. In conclusion, our device contributes to ultrasound training by providing a realistic ultrasound image, improving image understanding and skill development and allowing reliable bladder volume estimation.

Implementation of a standardized voiding management protocol to reduce unnecessary re-catheterization - A quality improvement project

OBJECTIVE

To design and implement a standardized postoperative voiding management protocol that accurately identifies patients with urinary retention and reduces unnecessary re-catheterization.

METHODS

A postoperative voiding management protocol was designed and implemented in patients undergoing major, inpatient, non-radical abdominal surgery with a gynecologic oncologist. No patients had epidural catheters. The implemented quality improvement (QI) protocol included: 1) Foley removal at six hours postoperatively; 2) universal bladder scan after the first void; and 3) limiting re-catheterization to patients with bladder scan volumes >150 ml. A total of 96 patients post-protocol implementation were compared to 52 patients pre-protocol. Along with baseline demographic data and timing of catheter removal, we recorded the presence or absence of urinary retention and/or unnecessary re-catheterization and postoperative urinary tract infection rates. Fisher's exact test and student's t-tests were performed for comparisons.

RESULTS

The overall rate of postoperative urinary retention was 21.6% (32/148). The new voiding management protocol reduced the rate of unnecessary re-catheterization by 90% (13.5% vs 2.1%, p = 0.01), without overlooking true urinary retention (23.1% vs 20.8%, p = 0.83). Additionally, there was a significant increase in hospital-defined early discharge prior to 11:00 AM (4.0% vs 22.0%, p = 0.022). There was no difference in the postoperative urinary tract infection rate between the groups (p = 1.00). Risk factors associated with urinary retention included older age (p < 0.01), use of medications with anticholinergic properties (p < 0.01), and preexisting urinary dysfunction (p < 0.01).

CONCLUSIONS

Implementation of this new voiding management protocol reduced unnecessary re-catheterization, captured and treated true urinary retention, and facilitated early hospital discharge.

A nonsurgical and nonpharmacological care bundle for preventing upper urinary tract damage in patients with spinal cord injury and neurogenic bladder

AIM

To establish a care bundle in spinal cord injury patients with neurogenic bladder to avoid upper urinary tract damage and to provide guidance for health care staff in use of nonsurgical and nonpharmacological adjunctive strategies to improve patients' clinical outcomes.

BACKGROUND

Prevention of upper urinary tract damage is critical in the management of spinal cord injury patients with a neurogenic bladder, but there are no authoritative guidelines or high-quality randomized controlled trials.

DESIGN

The study was conducted on the basis of Fulbrook and Mooney's seven-step method for care bundle development.

DATA SOURCES

The databases PubMed, Embase, Science Citation Index, the Cumulative Index to Nursing and Allied Health Literature, the National Guideline Clearinghouse, the Cochrane Library, China Biology Medicine, China National Knowledge Infrastructure, and China Dissertation Database were searched from the date of each database's inception to April 2017.

REVIEW METHODS

We evaluated the literature according to the Joanna Briggs Institute evidence pre-ranking and grade recommendation system (2014 version). The results were examined using a self-designed data extraction.

RESULTS

A three-element cluster including clean intermittent catheterization, bladder function training, and transcutaneous low-frequency pulsed electrical stimulation was formed.

CONCLUSION

The development of this bundle can provide a scientific basis for effective prevention of neurogenic upper urinary tract damage in clinical practice.

A single-center, prospective, randomized clinical trial to investigate the optimal removal time of the urinary catheter after laparoscopic anterior resection of the rectum: study protocol for a randomized controlled trial

Background

Urinary catheter placement is essential before laparoscopic anterior resection for rectal cancer. Whether early removal of the catheter increases the incidence of urinary retention and urinary tract infection (UTI) is not clear. This study aims to determine the optimal time for removal of the urinary catheter after laparoscopic anterior resection of the rectum.

Methods/design

A total of 220 participants meeting the inclusion criteria will be randomly assigned to an experimental group or a control group. The experimental group will have their urethral catheters removed on postoperative day 2 and the control group will have their urethral catheters removed on postoperative day 7. In both groups, catheter removal will be performed when the bladder is full. The incidence of urinary retention and UTI in the two groups will be compared to determine the optimal catheter removal time.

Discussion

This is a prospective, single-center, randomized controlled trial to determine whether early removal of the urinary catheter after laparoscopic anterior resection of the rectum will help to decrease the incidence of postoperative acute urinary retention and UTI.

Trial registration

ClinicalTrials.gov, NCT03065855. Registered on 23 February 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-019-3210-1) contains supplementary material, which is available to authorized users.

Post-operative urinary retention: Review of literature

Postoperative urinary retention (POUR) is one of the postoperative complications which is often underestimated and often gets missed and causes lot of discomfort to the patient. POUR is essentially the inability to void despite a full bladder in the postoperative period. The reported incidence varies for the wide range of 5%-70%. Multiple factors and etiology have been reported for occurrence of POUR and these depend on the type of anaesthesia, type and duration of surgery, underlying comorbidities, and drugs used in perioperative period. Untreated POUR can lead to significant morbidities such as prolongation of the hospital stay, urinary tract infection, detrusor muscle dysfunction, delirium, cardiac arrhythmias etc. This has led to an increasing focus on early detection of POUR. This review of literature aims at understanding the normal physiology of micturition, POUR and its predisposing factors, complications, diagnosis and management with special emphasis on the role of ultrasound in POUR.

The role of bladder volume in the success of external cephalic version

OBJECTIVE

Numerous studies have evaluated the factors associated with ECV success. Yet, bladder volume has never been examined. We hypothesize that maternal bladder volume may affect ECV success rate. We aim to evaluate the role of maternal bladder volume during external cephalic version (ECV) on the procedure success rates.

STUDY DESIGN

We reviewed prospective collected data of all patients who underwent ECV at our center during 2001-2012. The study group included 100 patients that underwent ECV with bladder volume below 400 ml. These patients were matched to 400 patients that underwent ECV with bladder volume equal or above 400 ml which composed the control group. Maternal and fetal characteristics and outcomes were compared.

RESULTS

ECV was successfully performed in 80/100 (80.0%) of patients in the study group as compared to 257/400 (64.3%) in the control group (P = 0.002). Factors associated with ECV success were older age (P = 0.003), having prior delivery (P < 0.0001), higher amniotic fluid index (AFI) (P = 0.001) and placenta located in the posterior wall (P = 0.001). In a logistic regression analysis, bladder volume was found to be an independent predictor of ECV success Odds radio (OR) for ECV success 2.5 (CI 1.42-4.34). Posterior placenta and higher AFI were found to be an independent predictors of ECV success as well; OR 2.7 (CI 1.74-4.34) and OR 1.07 (CI 1.02-1.13) respectively.

CONCLUSION

ECV is more successful in patient with bladder volume below 400 ml. Amniotic fluid volume and placental location were found as independent predictors of ECV outcome as well.

Postoperative urinary retention or difficulties to empty the bladder in young patients undergoing posterior spinal fusion for adolescent idiopathic scoliosis

BACKGROUND

Postoperative urinary retention has been reported to affect up to 27% of adults undergoing degenerative lumbar spine surgery and approximately one-third of children undergoing lower-extremity orthopedic surgery. No data exist on the incidence and risk factors of postoperative urinary tract retention/difficulties to empty the bladder in young patients undergoing instrumented posterior spinal fusion. We aimed to characterize incidence, risk factors and treatment of postoperative urinary retention (POUR) and difficulties to empty the bladder in young patients undergoing posterior spinal fusion (PSF) for idiopathic scoliosis.

METHODS

One hundred and eleven consecutive patients (mean age 16years [range, 11-21years], 81 females and 30 males) undergoing PSF for adolescent idiopathic scoliosis were screened after removal of urinary catheter postoperatively for inability to void and residual volume of urinary bladder. The latter was measured using ultrasound on two separate occasions. POUR and the need for intermittent catheterization were defined as an inability to void after catheter removal and documented full bladder with ultrasound (a residual of 300mL or more) or a significant residual volume after voiding (>2mL/kg or >100mL).

RESULTS

Fifty-one (46%) of the patients were either unable to void or had a clinically significant amount of residual volume after voiding. These fifty-one patients required intermittent catheterization for a mean of two days. Thirty patients (27%) had POUR, a residual volume of 300mL or more. Two (1.8%) patients experienced urinary tract infection postoperatively. Patients with urinary retention had a significantly higher mean intraoperative blood loss (mean 626mL vs. 464mL; p=0.020) and longer operation time (mean 3.3h vs. 2.8h; p=0.009) as compared with those not having urinary retention. In multivariate analyses the main risk factor for urinary retention was male gender (odds ratio 3.2 [95% confidence interval 1.1-9.2], p=0.028).

CONCLUSIONS

Postoperative voiding difficulties affect almost half of the patients with age under 21years undergoing PSF for idiopathic scoliosis. The main risk factors were increased intraoperative blood loss, longer length of surgery and male gender. POUR should be actively screened and treated in this patient population.

LEVEL OF EVIDENCE

Prospective Cohort Study II.

Non-invasive bladder volume measurement for the prevention of postoperative urinary retention: validation of two ultrasound devices in a clinical setting

Ultrasound scanning of bladder volume is used for prevention of postoperative urinary retention (POUR). Accurate assessment of bladder volume is needed to allow clinical decision-making regarding the need for postoperative catheterization. Two commonly used ultrasound devices, the BladderScan® BVI 9400 and the newly released Prime® (Verathon Medical®, Bothell, WA, USA), with or without the ‘pre-scan’ option, have not been validated in clinical practice. The aim of this study was to assess the performance of these devices in daily clinical practice. Between June and September 2016 a prospective observational study was conducted in 318 surgical patients (18 years or older) who needed a urinary catheter perioperatively for clinical reasons. For acceptable performance, we required that the volume as estimated by the BladderScan® differs by no more than 5% from the actual urine volume after catheterization. The Schuirmann’s two one-sided test was performed to assess equivalence between the BladderScan® estimate and catheterization. The BVI 9400® overestimated the actual bladder volume by + 17.5% (95% CI + 8.8 to + 26.3%). The Prime® without pre-scan underestimated by − 4.1% (95% CI − 8.8 to + 0.5%) and the Prime® with pre-scan underestimated by − 6.3% (95% CI − 11.6 to − 1.1%). This study shows that while both ultrasound devices were able to approximate current bladder volume, both BVI 9400® and Prime®—with and without pre-scan—were not able to measure the actual bladder volume within our predefined limit of ± 5%. Using the pre-scan feature of the Prime® did not further improve accuracy.

High Risk of Postoperative Urinary Retention in 1-Year-Old Cleft Palate Patients: An Observational Study

PURPOSE

Estimate the frequency of urinary catheterizations in a high-risk population of children.

DESIGN

It was a descriptive, observational study.

METHODS

Incidence of postoperative urinary retention was recorded for one-year-old cleft palate surgery patients admitted to the postanaesthesia care unit or pediatric intensive care unit at Rikshospitalet, Oslo University Hospital, Norway.

FINDING

Forty-five out of 70 patients (64%) were catheterized once or several times during the perioperative period. Furthermore, a total of 40 out of 54 patients (74%) had a bladder volume 60 mL or more measured by ultrasound scanner; 10 of these measured volumes exceeded twice the bladder capacity.

CONCLUSIONS

Postoperative urinary retention was discovered in 64% of patients; some of them were catheterized more than once during the perioperative period. Based on these data and the departmental procedure for postoperative care of these patients, the results indicated the need for an indwelling catheter.

Use of bladder volume measurement assessed with ultrasound to predict postoperative urinary retention

OBJECTIVE

Postoperative urinary retention (POUR) is a common complication after spinal anesthesia. Ultrasound (US) is a simple, non-invasive method to estimate bladder volume before and after surgery. Primary aim of the present study was to investigate utility of bladder volume measured before and after surgery in prediction of POUR risk. Secondary aim was to investigate necessity of urethral catheter use and risk of urethral catheter-related infections.

METHODS

Eighty patients who received spinal anesthesia for arthroscopic knee surgery were included in the study. Level and duration of sensory and motor block; bladder volume measured preoperatively, in post-anesthetic care unit (PACU), and when discharged from PACU; use of urethral catheter; and incidence of urinary tract infection data were recorded.

RESULTS

POUR was observed in 28.7% of patients. Length of time for sensory block regression was significantly shorter in patients without POUR (p=0.012). Spontaneous urination was not observed in 3 of 23 patients with POUR, although bladder volume was less than 600 mL. Bladder volume over 600 mL without urination was recorded in 20 patients. There was no statistical difference in preoperative bladder volume between patients who did or did not develop POUR. Bladder volume on admission to PACU was higher in patients with POUR (p=0.023). Urgency and dysuria were observed in 5 patients who required urethral catheterization during postoperative period. Urinary tract infection developed in 1 patient. There was no statistical difference in development of urinary tract infection between patient groups who did and did not undergo urethral catheterization.

CONCLUSION

Assessment of patient bladder volume with US before arthroscopic knee surgery may be used to foresee development of POUR. Avoiding elective urinary catheterization may reduce urinary infections.

Urinary Retention in Surgical Patients

Urinary retention is an important and potentially avoidable postoperative complication. Identifying risk factors for retention is important given expedient bladder decompression is important for long-term outcomes. Age, benign prostatic hyperplasia, and lower urinary tract symptoms are patient factors that predispose to retention. Surgery-related factors include operative time, intravenous fluid administration, type of anesthesia, and procedure type. The mainstay for treatment in the acute setting is Foley catheter placement. Starting alpha-blockers in men is also indicated as they increase voiding trial success. Long-term solutions for chronic retention include a variety of surgeries, with transurethral prostatectomy as the gold standard.

Diagnosis of Postoperative Urinary Retention Using a Simplified Ultrasound Bladder Measurement

BACKGROUND

In this study, we sought to determine whether a simplified ultrasound measurement of the largest transverse diameter, using a standard ultrasound machine, could be used to diagnose postoperative urinary retention (POUR). This method may replace expensive bladder volume measuring devices or a more complex ultrasound procedure (involving the measurement of 3 bladder diameters).

METHODS

Patients at risk of POUR if unable to void after orthopedic surgery were evaluated in the postanesthesia care unit before discharge. Bladder diameter was first measured using a portable ultrasound device (Vscan®; GE Healthcare, Wauwatosa, WI). An automated evaluation of bladder volume was then performed (Bladderscan® BVI 3000; Diagnostic Ultrasound, Redmond, WA). Finally, when a bladder catheterization was performed, the actual urinary volume was measured. The main outcome was a bladder volume ≥600 mL as measured using the automated ultrasound scanner (Bladderscan BVI 3000) or by catheterization. Correlations between bladder volumes and diameter were studied and receiver operating characteristic curves were constructed to determine the performance in predicting a bladder volume ≥600 mL. A "gray zone" approach was developed because a single cutoff value may not always be clinically significant.

RESULTS

One hundred patients were included and underwent a Bladderscan measurement. Urinary volume after catheterization was obtained in 49 patients. A significant correlation was found between the largest transverse diameter and urinary volumes assessed by the 2 methods (Bladderscan and catheterization). Pearson correlation coefficients were r = 0.80 (95% confidence interval [CI], 0.72-0.86; P < 0.001) and r = 0.79 (95% CI, 0.65-0.88; P < 0.001), respectively. The area under the receiver operating characteristic curves for the prediction of a bladder volume ≥600 mL were 0.94 (95% CI, 0.88-0.98) and 0.91 (95% CI, 0.79-0.97), respectively, for urinary volumes assessed by Bladderscan and catheterization. The optimal cutoff value was 9.7 cm for both methods. The gray zone was narrow, ranging from 9.7 to 10.7 cm thus limiting inconclusive measurements.

CONCLUSIONS

A simple ultrasound measurement of the largest transverse bladder diameter seemed to be helpful to exclude or confirm POUR.

Postoperative bladder catheterization based on individual bladder capacity: a randomized trial

BACKGROUND

Untreated postoperative urinary retention can result in permanent lower urinary tract dysfunction and can be prevented by timely bladder catheterization. The author hypothesized that the incidence of postoperative bladder catheterization can be decreased by using the patient's own maximum bladder capacity (MBC) instead of a fixed bladder volume of 500 ml as a threshold for catheterization.

METHODS

Randomized parallel-arm and single-blinded comparative effectiveness trial conducted in 1,840 surgical patients, operated under general or spinal anesthesia without an indwelling urinary catheter. Patients were randomized to either use their individual MBC (index) or a fixed bladder volume of 500 ml (control) as a threshold for postoperative bladder catheterization. Preoperatively, the MBC was determined at home by voiding in a calibrated bowl. All other bladder volumes were measured by ultrasound. Postoperatively, bladder catheterization was performed when spontaneous voiding was impossible, and the ultrasound measurement exceeded the threshold for the group in which the patient was randomized (500 or MBC). The primary outcome was the incidence of bladder catheterization.

RESULTS

The average MBC in the control group was 582 ml (±199 ml) and in the index group 611 ml (±209 ml). The incidence of catheterization decreased from 11.8% (107 of 909 patients) in the control group to 8.6% (80 of 931) in the index group (relative risk 0.73, 95% CI 0.55 to 0.96, P = 0.025). There were no adverse events in either group.

CONCLUSIONS

In patients undergoing surgery under general or spinal anesthesia using the MBC rather than a fixed 500 ml threshold for bladder catheterization is a safe approach that significantly reduces the incidence of postoperative bladder catheterizations.

Urinary retention following laparoscopic gynaecological surgery with or without 4% icodextrin anti-adhesion solution

BACKGROUND

Urinary retention is a recognised complication of laparoscopic surgery. Previous work showed an association with 4% icodextrin solution and urinary retention.

AIMS

To determine the incidence of urinary retention following laparoscopic gynaecological surgery with or without the use of 4% icodextrin.

METHODS

A prospective observational study of 147 women undergoing laparoscopic gynaecological surgery for benign pathology. Women had their planned laparoscopic procedure and either received icodextrin solution or nothing as determined by their treating surgeon at the time of the operation.

RESULTS

From May 2011 to February 2012, 147 women were approached to participate in the study; of whom, 124 women were included: 62 received icodextrin and 62 did not. The women in the non-icodextrin group were significantly older (P = 0.007) and had a higher BMI (P = 0.03) than those in the icodextrin group. Following surgery, 27/124 (21.8%) women had post-operative urinary retention. Icodextrin was associated with significantly more urinary retention (P = 0.017), but did not extend hospital admission significantly (P = 0.14). The administration of icodextrin was associated with resection of moderate- or severe-stage endometriosis involving multiple surgical sites, whereas women in the non-icodextrin group were more likely to be having a hysterectomy.

CONCLUSIONS

In this non-randomised study, there were significantly more women with post-operative urinary retention when icodextrin was used; however, this did not contribute to an extended hospital admission. While there may be confounding factors, women receiving icodextrin should be warned of the possibility of urinary retention post-operatively, but that this is unlikely to affect their stay in hospital.

Intermittent versus indwelling urinary catheterisation in hip surgery patients: a randomised controlled trial with cost-effectiveness analysis

BACKGROUND

Hip surgery is associated with the risk of postoperative urinary retention. To avoid urinary retention hip surgery patients undergo urinary catheterisation. Urinary catheterisation, however, is associated with increased risk for urinary tract infection (UTI). At present, there is limited evidence for whether intermittent or indwelling urinary catheterisation is the preferred choice for short-term bladder drainage in patients undergoing hip surgery.

OBJECTIVES

The aim of the study was to investigate differences between intermittent and indwelling urinary catheterisation in hip surgery patients in relation to nosocomial UTI and cost-effectiveness.

DESIGN

Randomised controlled trial with cost-effectiveness analysis.

SETTING

The study was carried out at an orthopaedic department at a Swedish University Hospital.

METHODS

One hundred and seventy hip surgery patients (patients with fractures or with osteoarthritis) were randomly allocated to either intermittent or indwelling urinary catheterisation. Data collection took place at four time points: during stay in hospital, at discharge and at 4 weeks and 4 months after discharge.

RESULTS

Eighteen patients contracted nosocomial UTIs, 8 in the intermittent catheterisation group and 10 in the indwelling catheterisation group (absolute difference 2.4%, 95% CI -6.9-11.6%) The patients in the intermittent catheterisation group were more often catheterised (p<0.001) and required more bladder scans (p<0.001) but regained normal bladder function sooner than the patients in the indwelling catheterisation group (p<0.001). Fourteen percent of the patients in the intermittent group did not need any catheterisation. Cost-effectiveness was similar between the indwelling and intermittent urinary catheterisation methods.

CONCLUSIONS

Both indwelling and intermittent methods could be appropriate in clinical practice. Both methods have advantages and disadvantages but by not using routine indwelling catheterisation, unnecessary catheterisations might be avoided in this patient group.

Avoiding bladder catheterisation in total knee arthroplasty: patient selection criteria and low-dose spinal anaesthesia

BACKGROUND

Bladder catheterisation may be inconvenient for patients, delay mobilisation and risk complications. We hypothesised that by excluding pre-operatively patients at high risk of post-operative urinary retention, the majority of patients could avoid perioperative catheterisation during low-dose spinal anaesthesia.

METHODS

Patients undergoing total knee arthroplasty were assigned if fit for spinal anaesthesia and without severe symptoms of lower urinary tract obstruction, gross incontinence, mobilisation difficulties hindering micturition and > 200 ml residual urine volume. Bladder volume was monitored by ultrasound and temporary catheterisation advised if > 400 ml.

RESULTS

Fifty-two patients (men 54%, age 65 ± 9 years, body mass index 31 ± 5, 30% with history of urinary tract problems) were included. Intrathecal hyperbaric bupivacaine given was 7.8 ± 1.08 mg and always 7.5 μg sufentanil providing sufficient anaesthesia in all cases. Crystalloid given during surgery was 8.5 ± 4.0 ml/kg. Voluntary micturition was reached by 46 patients (88%, confidence interval (CI) 79-97%), but six (12%, CI 3-21%) needed temporary catheterisation once (four men/two women). Larger bladder volumes were found in those catheterised than those with voluntary micturition on the pre-operative (131 ± 76 ml vs. 68 ± 57 ml, P = 0.03) and first post-operative bladder scan (445 ± 169 ml vs. 271 ± 129 ml, P = 0.004). All but two patients (96%) could be mobilised the same day. No patient suffered bladder dysfunction.

CONCLUSION

Low-dose spinal anaesthesia combined with simple selection criteria allowed for early mobilisation (96%) and avoidance of bladder catheterisation in the vast majority (88%) of patients undergoing total knee arthroplasty, and the rest (12%) only needed a single temporary catheterisation.

Diagnostic accuracy of retrograde and spontaneous voiding trials for postoperative voiding dysfunction: a randomized controlled trial

OBJECTIVE

To compare the diagnostic accuracy of two voiding trial methods to predict postoperative voiding dysfunction.

METHODS

Women undergoing operations for urinary incontinence, prolapse, or both urinary incontinence and prolapse from November 2009 and March 2010 were randomized into one of two groups: retrograde or spontaneous. All patients underwent both techniques of voiding trials with randomization determining order.

RESULTS

Fifty women were randomized to 25 per group. Failure rates were 62% for retrograde and 84% for spontaneous. Women who failed both had 12.6±14.4 days of retention compared with 2.5±2.1 days for those who failed only one method (P=.004). The retrograde method had 94.4% sensitivity and 58.1% specificity to detect postoperative voiding dysfunction lasting at least 7 days compared with the spontaneous method with 100% sensitivity and 25.8% specificity. Positive and negative predictive values for the retrograde method were 56.7% and 94.7%, respectively, compared with the spontaneous method with 43.9% and 100%. Retrograde was preferred by patients (51.1% compared with 44.4%) regardless of randomization.

CONCLUSION

The retrograde method is more accurate in evaluating postoperative voiding dysfunction, although both tests had a low positive predictive value. A longer period of retention was seen with failure of both methods. Retrograde was preferred by patients and provides an efficient alternative to the spontaneous method of voiding trial.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, www.clinicaltrials.gov, NCT01091844.

LEVEL OF EVIDENCE

I.

Key considerations of intermittent catheterisation

Intermittent catheterisation provides a safe and effective alternative to indwelling catheterisation for patients who require bladder drainage. It can be undertaken by health professionals in a variety of clinical settings for a range of clinical indications, and increasingly by patients themselves who use it as a long-term bladder management technique. The relative simplicity of the technique comes with the potential for health professionals to underestimate the skills required when considering a regimen of intermittent catheterisation and, perhaps more importantly, to underestimate the impact it may have on individual patients. The aim of this article is to consider intermittent catheterisation, its indications as a bladder management technique, and the potential psychological impact it may have on the patient, as well as how this may influence concordance.

Preoperative ultrasound monitoring can reduce postoperative bladder distension: a randomized study

OBJECTIVE

The aim of this study was to explore whether close preoperative ultrasound monitoring starting in the emergency room (ER) could prevent postoperative bladder distension among acute orthopaedic patients.

MATERIAL AND METHODS

A randomized controlled trial was conducted at a 650-bed level-2 centre in Sweden. Inclusion criteria were admittance via ER to an orthopaedic ward for acute surgery. Bladder volumes were measured with a portable ultrasound scanner (Bladderscan BVI 3000). In the intervention group, all patients were scanned in the ER and then regularly at the ward at predefined times until surgery. In the control group, no regular scanning was performed before surgery. During surgery, the same procedure was performed for both groups: bladder scanning immediately after arrival to the recovery room and continuous postoperative scanning until voiding. The primary outcome was postoperative bladder distension, defined as a bladder volume ≥500 ml. Secondary outcomes were postoperative urinary tract infection and hospital length of stay.

RESULTS

A total of 281 patients completed the study, 141 in the intervention group and 140 in the control group. Postoperative bladder distension was significantly higher in the control group (27.1% vs 17.0%; p = 0.045, 95% confidence interval 4.9-19.8) in the intention-to-treat, per-protocol and as-treated analyses. No statistical difference was found between the intervention group and the control group regarding the secondary outcomes.

CONCLUSIONS

Frequent bladder monitoring starting in the ER can reduce postoperative bladder distension among acute orthopaedic patients. A preoperative bladder monitoring protocol should be implemented early in the ER for all patients admitted for acute orthopaedic procedures.

Risk factors of post-operative urinary retention in hospitalised patients

BACKGROUND

Post-operative urinary retention (POUR) is most accurately determined by using ultrasound to measure bladder volume. The aim of this study was to define the risk factors of POUR in the recovery room in hospitalised patients.

METHODS

An ultrasound-determined bladder volume ≥400 ml at arrival in the recovery room was used to define POUR. Multivariate regression analysis was used to identify patient and system factors linked to POUR in 773 consecutive hospitalised patients who had undergone orthopaedic, abdominal, gynaecological or plastic surgery without an indwelling urinary catheter.

RESULTS

We found the incidence of POUR to be 13%. The lack of pre-operative voiding, use of regional anaesthesia, anaesthesia time >2 h and emergency surgery were all independent risk factors for POUR.

CONCLUSIONS

The detected incidence of POUR at arrival in the recovery room was rather high but had easily identifiable risk factors. We recommend pre-operative voiding whenever possible. Routine bladder scanning at arrival in the recovery room should be considered, especially after spinal anaesthesia, emergency surgery or when the anaesthesia time exceeds 2 h.

Less urinary tract infection by earlier removal of bladder catheter in surgical patients receiving thoracic epidural analgesia

BACKGROUND AND OBJECTIVES

It is common practice to catheterize the bladder in the presence of epidural analgesia and to leave the bladder catheter in situ to avoid postoperative urinary retention. However, bladder catheterization carries the risk for urinary tract infection (UTI). The objective of this randomized control trial was to assess whether the incidence of UTI will differ among patients receiving standard care and patients who have the bladder catheterization discontinued on the morning after surgery with the epidural still functioning.

METHODS

Patients at low risk for postoperative urinary retention, scheduled for thoracic and abdominal surgery and receiving continuous thoracic epidural analgesia, were randomized on the morning after surgery to 2 groups: in the early removal group (n = 105), the bladder catheter was removed on the same morning after surgery, whereas in the standard group (SG) (n = 110), the bladder catheter was removed when epidural analgesia was discontinued (3-5 days). Urinary bladder volume was assessed by ultrasound. Primary and secondary outcomes were the incidence of UTI and rate of recatheterization.

RESULTS

Two hundred fifteen patients were randomized. There were 17 UTI cases in total, with 15 (14%) in the SG and 2 (2%) in the early removal group (P = 0.004). The incidence of recatheterizations was not different between the 2 groups (P = 0.09) and did not correlate with the site of epidural insertion. When matched for the types of surgery, the duration of hospital stay was longer in the patients who contracted UTI (P = 0.004). There were more patients older than 65 years in the SG.

CONCLUSIONS

Leaving the bladder catheter as long as the epidural analgesia is maintained results in a higher incidence of UTI and prolonged hospital stay. Removal of the bladder catheter on the morning after surgery does not lead to higher rate of catheterizations.

[Validity and reliability of bladder ultrasound imaging for noninvasive estimation of urine volume in a major outpatient surgery department]

OBJECTIVE

To assess the validity and reliability of bladder ultrasound imaging for noninvasive estimation of urine volume, residual volume after voiding, volume before anesthetic induction and after surgery, and volume on sensing an urge to void.

PATIENTS AND METHODS

Study of a prospective series of 47 ASA 1-3 patients aged 18 to 79 years undergoing major outpatient surgical procedures under general anesthesia (n = 24) or regional anesthesia and sedation (n = 23). Urine volume was measured at baseline and on recovery (bladder volume by ultrasound and voided volume in a flask) and at the end of surgery (ultrasound only). The reliability and validity of the ultrasound estimation was calculated.

RESULTS

Agreement (intraclass correlation coefficient [ICC]) between 4 ultrasound-image estimations at baseline and the measured amount collected in a flask ranged from 0.70 to 0.86. The inter- and intra-measurement reliability was high, with ICC values greater than 0.80. The median error of estimation by ultrasound, with respect to measurement in the flask, was 23% at baseline and 29% after recovery. The amount in the flask was greater.

CONCLUSIONS

Ultrasound monitoring of urine in the bladder is reliable and valid, particularly for small volumes. The procedure is tolerated by patients.

Unilateral anesthesia does not affect the incidence of urinary retention after low-dose spinal anesthesia for knee surgery

We evaluated whether unilateral low-dose spinal anesthesia may reduce the likelihood of postoperative urinary retention. Forty patients scheduled for knee arthroscopy randomly received bilateral (n = 20) or unilateral (n = 20) spinal anesthesia with 6-mg hyperbaric bupivacaine 0.5%. The incidence of urinary retention (>500 mL) assessed with an ultrasound device (Bladderscan) and subsequent temporary catherization was 7/20 patients in the bilateral versus 6/20 in the unilateral group (not significant). We concluded that unilateral low-dose spinal anesthesia does not further decrease the likelihood of urinary retention. Our results demonstrate the value and necessity of monitoring bladder volume postoperatively.

Evaluation of a non-invasive bladder volume measurement in children

OBJECTIVE

Postoperative urinary retention (PUR) is associated with overdistension of the bladder. The prevention of PUR by routine catheterization may increase the risk of urinary tract infection. Postoperative monitoring of the bladder volume by ultrasound to prevent PUR is reliable in adults, but has not been evaluated in children.

MATERIAL AND METHODS

The BladderScan BVI 6200, an ultrasound device specifically designed for children, was assessed. Forty patients who required urinary catheter placement during surgery or during intensive care unit stay were entered into this blinded calibration study. An assessment of bladder urine volume by ultrasound was performed before and after catheterization in surgical patients. In these patients and intensive care patients 0, 2.5 or 5 ml/kg sterile normal NaCl was injected through the bladder catheter and the catheter was clamped. Volumes estimated with ultrasound were compared with measured catheter drainage or/and injected volume after the scan.

RESULTS

The mean relative difference (bias) between the ultrasound estimate and the injected volume was -20% (95% confidence interval 140 to -180%). Precision, estimated using the Wilcoxon signed ranks test, showed a significant difference (Z = -3.25, p = 0.001) between the ultrasound-estimated volumes and the injected volumes.

CONCLUSIONS

This study could not confirm good agreement between the ultrasound-estimated volumes and the injected volumes at volumes below 5 ml/kg. Bladder volumes were underestimated with a very broad 95% confidence interval. The ultrasound device should not replace current clinical assessment.