IMU-Assisted Manual 3D-Ultrasound Imaging Using Motion-Constrained Swept-Fan Scans.

Three-dimensional (3D) ultrasonic imaging can enable post-facto plane of interest selection. It can be performed with devices such as wobbler probes, matrix probes, and sensor-based probes. Ultrasound systems that support 3D-imaging are expensive with added hardware complexity compared to 2D-imaging systems. An inertial measurement unit (IMU) can potentially be used for 3D-imaging by using it to track the motion of a one-dimensional array probe and constraining its motion in one degree of freedom (1-DoF) rotation (swept-fan). This work demonstrates the feasibility of an affordable IMU-assisted manual 3D-ultrasound scanner (IAM3US). A consumer-grade IMU-assisted 3D scanner prototype is designed with two support structures for swept-fan. After proper IMU calibration, an appropriate KF-based algorithm estimates the probe orientation during the swept-fan. An improved scanline-based reconstruction method is used for volume reconstruction. The evaluation of the IAM3US system is done by imaging a tennis ball filled with water and the head region of a fetal phantom. From fetal phantom reconstructed volumes, suitable 2D planes are extracted for biparietal diameter (BPD) manual measurements. Later, in-vivo data is collected. The novel contributions of this paper are (1) the application of a recently proposed algorithm for orientation estimation of swept-fan for 3D imaging, chosen based on the noise characteristics of selected consumer grade IMU (2) assessment of the quality of the 1-DoF swept-fan scan with a deflection detector along with monitoring of maximum angular rate during the scan and (3) two probe holder designs to aid the operator in performing the 1-DoF rotational motion and (4) end-to-end 3D-imaging system-integration. Phantom studies and preliminary in-vivo obstetric scans performed on two patients illustrate the usability of the system for diagnosis purposes.

Survival outcomes of postchemotherapy retroperitoneal lymph node dissection for nonseminomatous germ cell tumors: A retrospective cohort study from a single tertiary center in South India.

Introduction: Chemotherapy, postchemotherapy retroperitoneal lymph node dissection (pcRPLND), and metastasectomy remain the standard of care for the management of advanced nonseminomatous germ cell tumor (NSGCT). Methods: We retrospectively studied 73 patients who had pcRPLND at a single tertiary-care center (2003-2022). Surgical and clinicopathological features and oncological outcomes are presented. Results: The mean age was 28.27 years (15-48). Three-fourths had Stage III disease at diagnosis. International Germ Cell Cancer Collaborative Group risk stratification was 54.54% and 21.21% in intermediate risk, and poor risk, respectively. Sixty-two patients had Standard, 7 had Salvage and 4 underwent Desperation pcRPLND. Eleven patients (15.06%) required adjunctive procedures. Thirteen patients (17.8%) had ≥ class 3 Clavien-Dindo complications and postoperative mortality occurred in 5 (6.8%) patients. The histopathologies (HPE) of the pcRPLNDs were necrosis, teratoma, and viable tumor in 39.7%, 45.2%, and 15.1%, respectively. Seven patients underwent metastasectomy. An 85% size reduction in the size of RPLN predicted necrosis. There was 71.4% concordance between pcRPLND and metastasectomy HPEs. The median follow-up was 26.72 months (inter-quartile range - 13.25-47.84). The 2-year recurrence-free survival (RFS) rate was 93% (95% confidence interval [CI]-83%-97%) and the overall survival (OS) rate was 90% (95% CI-80%-95%). This is the largest series of pcRPLND for NSGCT in India to our knowledge. Conclusion: Although most of the cohort belonged to stage III, an RFS and OS rate of >90% at 2 years was achieved. We believe that successful management of postchemotherapy residual masses in NSGCT is contingent on the availability of multidisciplinary expertise and is therefore best done at tertiary-care referral centers.

Role of MRI in the evaluation of acute pyelonephritis in a high-risk population with renal dysfunction: a prospective study.

AIMS: This study aims to evaluate the (a) accuracy of conventional and diffusion-weighted-imaging (DWI) sequences in the diagnosis of acute pyelonephritis and (b) minimum apparent diffusion coefficient (ADC) values for the diagnosis of acute pyelonephritis and the differentiation of renal abscesses from acute pyelonephritis. MATERIALS AND METHODS: Ultrasound, conventional MRI sequences, and DWI were used to evaluate the kidneys in 68 patients suspected to have acute pyelonephritis. Multiple similar regions of interest (ROIs) were placed over the renal parenchyma with visually identifiable diffusion restriction, over the non-diffusion-restricted renal parenchyma of affected kidneys and over the normal kidneys. Corresponding minimum ADCs were noted for analysis. Pyelonephritis was confirmed based on clinical criteria, laboratory findings, and by resolution/development of known complications of pyelonephritis. RESULT: DWI showed the highest sensitivity(100%), while DWI read with T2-weighted imaging (both being positive) showed the highest specificity(100%) for the diagnosis of acute pyelonephritis in our population with a high baseline creatinine. The minimum-ADC of the nephritic diffusion-restricted area in patients with confirmed pyelonephritis was significantly lower than the minimum-ADC in patients without pyelonephritis [(0.934 ± 0.220, mean ± SD) vs (1.804 ± 0.404) × 10-3 s/mm2] (p < 0.001). ROC cut-off of minimum-ADC for the diagnosis of acute pyelonephritis was 1.202 × 10-3 s/mm2 (area under curve 0.978). The minimum-ADC of the abscesses were significantly lower when compared to the minimum-ADC of the nephritic diffusion-restricted portion of the same kidney [(0.633 ± 0.248) vs (0.850 ± 0.191) × 10-3 s/mm2] (p < 0.001). CONCLUSION: DWI is an excellent stand-alone imaging tool that can be combined with conventional sequences for the diagnosis of APN even in patients with high serum-creatinine or other contraindications to intravenous contrast. Further, ADC values can be used to differentiate between renal abscesses and uncomplicated pyelonephritis.

Emergency Department Resuscitative Endovascular Balloon Occlusion of the Aorta in Trauma Patients With Exsanguinating Hemorrhage: The UK-REBOA Randomized Clinical Trial.

Importance: Bleeding is the most common cause of preventable death after trauma. Objective: To determine the effectiveness of resuscitative endovascular balloon occlusion of the aorta (REBOA) when used in the emergency department along with standard care vs standard care alone on mortality in trauma patients with exsanguinating hemorrhage. Design, Setting, and Participants: Pragmatic, bayesian, randomized clinical trial conducted at 16 major trauma centers in the UK. Patients aged 16 years or older with exsanguinating hemorrhage were enrolled between October 2017 and March 2022 and followed up for 90 days. Intervention: Patients were randomly assigned (1:1 allocation) to a strategy that included REBOA and standard care (n = 46) or standard care alone (n = 44). Main Outcomes and Measures: The primary outcome was all-cause mortality at 90 days. Ten secondary outcomes included mortality at 6 months, while in the hospital, and within 24 hours, 6 hours, or 3 hours; the need for definitive hemorrhage control procedures; time to commencement of definitive hemorrhage control procedures; complications; length of stay; blood product use; and cause of death. Results: Of the 90 patients (median age, 41 years [IQR, 31-59 years]; 62 [69%] were male; and the median Injury Severity Score was 41 [IQR, 29-50]) randomized, 89 were included in the primary outcome analysis because 1 patient in the standard care alone group declined to provide consent for continued participation and data collection 4 days after enrollment. At 90 days, 25 of 46 patients (54%) had experienced all-cause mortality in the REBOA and standard care group vs 18 of 43 patients (42%) in the standard care alone group (odds ratio [OR], 1.58 [95% credible interval, 0.72-3.52]; posterior probability of an OR >1 [indicating increased odds of death with REBOA], 86.9%). Among the 10 secondary outcomes, the ORs for mortality and the posterior probabilities of an OR greater than 1 for 6-month, in-hospital, and 24-, 6-, or 3-hour mortality were all increased in the REBOA and standard care group, and the ORs were increased with earlier mortality end points. There were more deaths due to bleeding in the REBOA and standard care group (8 of 25 patients [32%]) than in standard care alone group (3 of 18 patients [17%]), and most occurred within 24 hours. Conclusions and Relevance: In trauma patients with exsanguinating hemorrhage, a strategy of REBOA and standard care in the emergency department does not reduce, and may increase, mortality compared with standard care alone. Trial Registration: isrctn.org Identifier: ISRCTN16184981.

"Keep it simple - a lesson from COVID-19": highlighting the utility of chest X-rays in ARDS-associated illnesses through the Zonal Scoring System.

Purpose: The post-pandemic era calls for appropriate literature on chest X-ray score cut-offs, enabling swift categorization and faster radiological reporting of patients with acute respiratory distress syndrome (ARDS)-like illnesses, hence prompting healthcare equity in low-resource centres where extortionate modalities of imaging such as computed tomography (CT) are unavailable. In this study, we aim to bridge the literature gap using the versatile zonal scoring system. Material and methods: This retrospective cohort study uses data from 751 COVID-19 RT-PCR+ patients. Concordant chest radiograph (CXR) scores were reported, and inter-rater reliability was measured using kappa indices. receiver operating characteristic curves were used to establish cut-off scores for the outcomes of interest: mild or severe disease, admission to an intensive care unit (ICU), and intubation. Categorical data were expressed using means and percentages, and c2 or t-tests were used for comparison at an a level of 0.05. Unadjusted odds ratios for each outcome of interest vs. CXR score and comorbidity were then calculated using binary logistic regression. Results: CXR findings included infiltrates (46.07%), pleural effusions (7.05%), consolidation and fibrosis (4.43%), pneumothoraces (2.71%), and cardiomegaly (2.26%). Most patients had an index CXR score of 0 (54.19%). The index cut-off score of ≤ 1 (82.95, 81.68) was established for mild disease, ≥ 4 for severe disease (85.71, 83.99), ≥ 3 for ICU admission (86.90, 71.91), and ≥ 4 for intubation (87.61, 72.90). Hypertension, type 2 diabetes mellitus, hypothyroidism, history of ischaemic heart disease, and history of tuberculosis were independent risk factors for a high CXR index score, intubation, and ICU admission. Conclusions: CXR scores can be effectively used in low-resource settings for triaging patients, maintaining records, and disease prognostication.

Somatosensory evoked potential loss due to intraoperative pulse lavage during spine surgery: case report and review of signal change management.

Intraoperative neurophysiologic monitoring (IONM) includes various neurophysiologic tests which assess the functional integrity of the central and peripheral nervous systems during surgical procedures which place these structures at risk for iatrogenic injury. The rational for using IONM is to provide timely feedback of changes in neural function to enable the reversal of such insult before the development of irreversible neural injury. There are various causes of intraoperative loss of neuromonitoring signals and it is important to systematically rule out all possible causes quickly and thoroughly in order to target the cause of signal loss, correct it and take measures to prevent the same in the future. One such rare cause, is targeted and pressurized cold (room temperature) irrigation of the surgical site, which may induce irritation and vasospasm leading to ischemia of the affected portion of the spinal cord, hence leading to signal changes. We present this case to stress the importance of having knowledgeable members of the team who are well acquainted with all aspects of monitoring in close proximity to the operating room, so as to minimize troubleshooting time. Furthermore, we suggest the use of warm (body temperature) saline during irrigation to the surgical site, especially when using pressurized irrigation systems.

Urethral duplication with unusual cause of bladder outlet obstruction.

A 12-year-old boy presented with poor flow and recurrent urinary tract infections following hypospadias repair at the age of 3 years. The evaluation revealed urethral duplication with a hypoplastic dorsal urethra and patent ventral urethra. He also had duplication of the bladder neck, and on voiding cystourethrogram the ventral bladder neck appeared hypoplastic and compressed by the dorsal bladder neck during voiding. The possibility of functional obstruction of the ventral urethra by the occluded dorsal urethra was suspected, and he underwent a successful urethro-urethrostomy.

Quantitative longitudinal evaluation of diaschisis-related cerebellar perfusion and diffusion parameters in patients with supratentorial hemispheric high-grade gliomas after surgery.

Decreased cerebral blood volume (CBV) in contralateral cerebellar gray matter (cGM) in conjunction with cerebellar white matter (cWM) damage, consistent with crossed cerebro-cerebellar diaschisis (cCCD) develop following supratentorial hemispheric stroke. In this study, we investigated the longitudinal evolution of diaschisis-related cerebellar perfusion and diffusion tensor-imaging (DTI) changes in patients after surgery for supratentorial brain tumors. Eight patients (M:F 5:3, age 8-22 years) who received surgery for supratentorial high-grade gliomas were evaluated. Initial MRI studies were performed 19-54 days postoperatively, with follow-ups at 2- to 3-month intervals. For each study, parametric maps of the cerebellum were generated and coregistered to T1-weighted images that had been previously segmented for cGM and cWM. Aggregate mean values of CBV, cerebral blood flow (CBF), and fractional anisotropy (FA) were obtained separately for cGM and cWM, and asymmetry indices (AIs) were calculated. Hemodynamic changes were more robust in cGM than in cWM. Seven patients showed decreased perfusion within cGM contralateral to the supratentorial lesion on the first postoperative study, and asymmetry was significant for both CBV (p = 0.008) and CBF (p < 0.01). For CBV, follow-up studies showed a significant trend towards recovery (p < 0.02). DTI changes were more pronounced in cWM. FA values suggested a "paradoxical" increase at initial follow-up, but steadily declined thereafter (p = 0.0003), without evidence of subsequent recovery. Diaschisis-related hemodynamic alterations within cGM appear on early postoperative studies, but CBV recovers over time. Conversely, cWM DTI changes are delayed and progressive. Although the clinical correlates of cCCD are yet to be elucidated, better understanding of longitudinal structural and hemodynamic changes within brain remote from the area of primary insult could have implications in research and clinical rehabilitative strategies.

An early loaded implant-supported mandibular complete arch fixed prosthesis in a young completely edentulous patient: a case report.

The restoration of the mandibular arch up to the first molars with 5 one-piece implants presents a viable and cost-effective treatment plan in patients with adequate bone volume and favorable ridge relationships. The early loading of the implants with a provisional restoration reduces the period of edentulousness and restores the patient's ability to eat, talk, and smile effectively. Implants in younger patients prevent resorption of the residual alveolar ridge. This article presents a case report of the restoration of an edentulous mandibular arch with an early loaded implant-supported fixed restoration in a young patient.

Pseudotumor Deltoideus: Touch Me Not Lesion of the Humerus.

Pseudotumor deltoideus is a localized region of irregular cortical thickening at the deltoid insertion that causes a diagnostic quandary for radiologists due to its unusual radiological characteristics. It is benign in origin, with the potential to act as a tumor stimulator, and has a variety of anatomic variants. The lesions can be characterized on an X-ray by an area of lucency at or around the deltoid tuberosity and a cortical irregularity or nearby eccentric marrow abnormality on computed tomography (CT)/magnetic resonance imaging (MRI). The presence of cortical thickening and lucency at the deltoid insertion are unusual radiological findings that provide a diagnostic challenge. In this article, we provide cases of shoulder pain together with radiological imaging to make this previously underappreciated condition more understandable. Further evaluation with CT/MRI should be performed in all cases of shoulder pain with conventional radiographic findings of cortical thickening and intracortical lucency. The diagnosis of the condition is aided by the presence of elongated lucency on CT and T2 hyperintensity in the cortex of the proximal humerus. The clinical and imaging characteristics are important in the diagnosis of this condition. It must not be confused for infection or malignancy, and a biopsy must never be attempted.

Co-existing Paraganglioma, Cholesteatoma, and Otomastoiditis With Overlapping Imaging Features: A Diagnostic Challenge.

Head and neck paragangliomas are rare neuroendocrine tumors arising from the autonomic nervous system. Imaging hallmarks of paragangliomas of the head and neck include an enhancing soft-tissue mass in the carotid space, jugular foramen, or tympanic cavity on computed tomography; a salt-and-pepper appearance on standard spin-echo magnetic resonance imaging; and an intense blush on angiography. Imaging studies depict the location and extent of tumor involvement, help determine the surgical approach, and predict operative morbidity and mortality. However, an atypical presentation of paragangliomas, especially when co-existing with other middle ear pathologies that have overlapping imaging findings, can often be misleading. Here, we report a case of simultaneous occurrence of paraganglioma, cholesteatoma, and otomastoiditis in a young adult female.

Atypical Hepatic Hemangioma With Progressive Centrifugal Enhancement Pattern Mimicking Malignant Liver Lesion.

Hepatic hemangioma is a common benign vascular hepatic lesion with typical imaging features. However, hepatic hemangiomas with atypical radiological characteristics can sometimes be diagnostically challenging. Here, we report a case of an elderly patient with colonic adenocarcinoma who was incidentally found to have an atypical hepatic hemangioma showing a progressive centrifugal enhancement pattern instead of a typical centripetal pattern on contrast-enhanced computed tomography mimicking a malignant liver lesion.

Assessment of Mandibular Canal Using Cone-Beam Computed Tomography (CBCT) and Its Relevance in Post-Operative Neurosensory Disturbances Following Bilateral Sagittal Split Osteotomy Setback.

AIM: Damage to the inferior alveolar nerve (IAN) during bilateral sagittal split osteotomy (BSSO) causes neurosensory disturbances (NSD) of the lower lip and chin. The study aims to investigate the pre-operative position and course of the mandibular canal using cone-beam computed tomography (CBCT) and orthopantomogram (OPG) and compare if there is any difference in NSD following the BSSO setback procedure. MATERIALS AND METHODS: This is an observational study. This study was conducted in the Department of Oral and Maxillofacial Surgery, Mar Baselios Dental College, Kothamangalam, from November 2017 to October 2019. Thirty patients undergoing BSSO setbacks are selected based on the inclusion and exclusion criteria and randomly grouped into two groups - group A (15) and study group B (15). OPG was done for both groups as it was required during surgical orthodontic evaluation and preoperative assessment of the mandibular canal was done using CBCT in group B. Neurosensory assessment was done in all the patients and compared the results. RESULTS: NSD were reported in all the patients on the first postoperative day. The correlation between subjective and objective evaluation showed absolute coincidence but nearly all the patients returned to their presurgical situation within six months in group B and one year in group A who had NSD problems. CONCLUSION: From the study, it can be concluded that a CBCT scan is a useful and reliable modality in the pre-operative evaluation of the mandibular canal in patients undergoing BSSO setback procedures, which helps to improve the patient's post-operative care and quality of life.

Spontaneous Epidural Hematoma in Sickle Cell Crisis: A Case Report.

Epidural hematoma (EDH) classically occurs secondary to trauma. Spontaneous EDH is uncommon and can be a rare complication of sickle cell disease (SCD). We report the case of a 20-year-old Indian male with sickle cell anemia, who presented with a sickling bony crisis and suffered a non-traumatic EDH within 24 hours of admission. A 20-year-old male presented with generalized body pain, suggestive of a sickling bony crisis. He was promptly admitted and received standard treatment for the same. The next day, he developed severe right-sided headache, associated with orbital pain, decreased movements on the right side, and altered sensorium. He had a Glasgow coma scale score of 8/15, and reduced power of the right upper limb and lower limb. Computed tomography (CT) and magnetic resonance imaging (MRI) of the brain showed a left-sided large parieto-temporal epidural hematoma with midline shift and mass effect. He underwent emergency decompressive craniotomy and evacuation of the hematoma, following which he recovered well, with no residual deficits. Spontaneous EDH is being increasingly reported in SCD. Possible mechanisms include skull bone infarction, altered skull bone anatomy due to extramedullary hematopoiesis, and venous congestion due to sluggish blood flow in diploic veins. In our patient, altered skull anatomy appeared to be the causative mechanism. Early identification of EDH and aggressive neurosurgical management is crucial to survival and a good prognosis.

Opioid Alternatives in Spine Surgery: A Narrative Review.

Adequate analgesia is known to improve outcomes after spine surgery. Despite recent attention highlighting the negative effects of narcotics and their addiction potential, opioids have been the mainstay of management for providing analgesia following spine surgeries. However, side effects including hyperalgesia, tolerance, and subsequent dependence restrict the generous usage of opioids. Multimodal analgesia regimens acting through different mechanisms offer significant opioid sparing and minimize the side effects of individual drugs. Hence, they are being increasingly incorporated into enhanced recovery protocols. Multimodal analgesia includes drugs such as N-methyl-D-aspartate antagonists, nonsteroidal anti-inflammatory drugs and membrane-stabilizing agents, neuraxial opioids, local anesthetic infiltration, and fascial compartment blocks. Analgesia started before the painful stimulus, termed preemptive analgesia, facilitates subsequent pain management. Both nonsteroidal anti-inflammatory drugs and neuraxial analgesia have been conclusively shown to reduce opioid requirements after spine surgery, and there is a resurgence of interest in the use of low-dose ketamine or methadone. Neuraxial narcotics offer enhanced analgesia for a longer duration with lower dosage and side effect profiles compared with systemic opioid administration. Fascial compartment blocks are increasingly used as they provide effective analgesia with fewer adverse effects. In this narrative review, we will discuss multimodality analgesic regimens incorporating opioid-sparing adjuvants to manage pain after spine surgery.

Adult renal angiomyolipomas: A retrospective analysis of the histological subtypes and their clinicoradiological correlates.

Background: Renal angiomyolipomas (AMLs) are rare, benign mesenchymal tumors of the kidney. Asian data on the prevalence of the subtypes of AMLs and their association with tuberous sclerosis are sparse prompting us to evaluate the clinicopathological characteristics of these tumors. Materials and Methods: We included cases diagnosed from 2001 to 2021 extracting demographic details, clinical presentation, syndromic association with tuberous sclerosis, and preoperative clinicoradiological features from the electronic medical records. Results: Ninety-five cases of adult renal AML were diagnosed among 2402 renal tumors, a prevalence of 3.95%. Forty tumors (42%) were detected incidentally; two patients had life-threatening retroperitoneal hemorrhage. Tuberous sclerosis complex (TSC) was associated with ten cases (10.5%). These patients were a decade younger than those in the non-TSC group (P = 0.008) and had bilateral, multiple, and larger tumors (P = 0.0009, 0.001, and 0.047, respectively). Microscopically, classic and epithelioid subtypes were seen in 87 (91.6%) and 8 cases (8.4%), respectively. Hemorrhage was more common in the epithelioid subtype (P = 0.13). HMB-45, melan-A, and smooth muscle actin immunohistochemistry were useful in cases which lacked the prototypical classic histology and for confirming a diagnosis of epithelioid AML. Conclusions: The prevalence of renal AML in our series was four times higher, and the mean age at diagnosis was a decade earlier than that reported in Western literature but similar to data from two Asian countries. Similar studies from other countries will help ascertain if these differences in prevalence can be attributed to ethnic differences.

End-of-Treatment FDG PET-CT (EOT-PET) in Patients with Post-Chemotherapy Masses for Seminoma: Can We Avoid Further Intervention?

Anjana JoelContext Patients with seminoma present with advanced disease. End-of-treatment (EOT) positron emission tomography-computed tomography (PET-CT) is done to assess response and direct management of post-chemotherapy residual masses. Purpose This article assesses the utility of EOT PET-CT in the management of post-chemotherapy residual lymph nodal masses seminoma. Materials and Methods We analyzed all patients with seminoma who underwent an EOT PET-CT from January 2015 to January 2020 at our center and calculated the positive predictive value (PPV) and negative predictive value (NPV) of EOT PET-CT in the entire cohort of patients and among subgroups. Results A total of 34 male patients underwent EOT PET-CT. Fourteen (41.2%) were stratified as good risk and 20 (58.8%) as intermediate risk. The median follow-up was 23 months (interquartile range: 9.75-53 months). In 23 patients there were residual masses of size more than 3 cm at the EOT PET scan. EOT PET was positive as per the SEMPET criteria in 18 (78%) out of 23 patients. None underwent retroperitoneal lymph node dissection. All four who underwent image-guided biopsy, showed only necrosis on pathology. One patient with positive mediastinal node (standardized uptake value 13.6) had granulomatous inflammation. There was no relapse or progression during this period of follow-up. The NPV for EOT PET-CT for the entire cohort, > 3 cm, and > 6 weeks cutoff were 100%, respectively. The PPV for EOT PET-CT for the entire cohort, > 3 cm residual mass, and > 6 weeks cutoff were 8.7, 11.11, and 6.67%, respectively. Conclusion EOT PET-CT has a low PPV and high NPV in predicting viable tumor in post-chemotherapy residual masses among patients with seminomatous germ cell tumors. If required, EOT PET positivity can be confirmed by a biopsy or reassessed with a repeat PET-CT imaging to document persistent disease prior to further intervention.

Can rectal catheters be avoided during paediatric urodynamic studies?

Objective: To determine if the interpretation of urodynamic studies (UDS) in children without a rectal catheter may be similar to multi-channel studies, as UDS in children are challenging and can sometimes be difficult to interpret. Patients and methods: In this retrospective pilot study, 115 paediatric pressure-flow studies were included. A blinded investigator was given two sets of UDS traces. The first set had the vesical trace of all children and the second set had the multi-channel trace. The agreement between the interpretations of both the sets was tested by Cohen's κ, and sensitivity, specificity, and predictive values were expressed with 95% confidence intervals (CIs). The voiding pattern was compared and Pearson's correlation coefficient was used to analyse the pressure at maximum urinary flow (Qmax). Results: The most common indications for UDS were neurogenic bladder and posterior urethral valves. The interpretation of compliance and detrusor overactivity by single-channel analysis had a positive predictive value of 92.1% (95% CI 84.7-96.1%) and 89.4% (95% CI 78.3-95.6%), respectively, and a negative predictive value of 100% and 97.1% (95% CI 89.5-99.2%) respectively, in comparison to multi-channel analysis. Children with underactive detrusor were identified reliably by analysing the straining pressure pattern and flow curve. Amongst children who voided, the pressure at Qmax showed a moderate correlation (Pearson's coefficient = 0.53) between the two groups. Conclusion: Rectal catheters may be avoided in a carefully selected group of children undergoing UDS who only need filling phase assessment. Abbreviations: DO: detrusor overactivity; EBC: expected bladder capacity; Pabd: abdominal pressure; Pdet: detrusor pressure; PUV: posterior urethral valve; (N)(P)PV: (negative) (positive) predictive value; Pves: vesical pressure; Qmax: maximum urinary flow rate; UDS: urodynamic studies; UI: urinary incontinence.