Goniometer not better than unaided visual inspection at estimating ventral penile curvature on plastic models

Hypospadias-associated penile curvature assessment and management: A global survey of current practice

INTRODUCTION

Our goal was to assess how surgical management of hypospadias-associated penile curvature (HAPC) varies across continents, focusing on factors that influence assessment and decision-making.

METHODS

Members of the European Society of Pediatric Urology (ESPU), Society of Pediatric Urology (SPU), and Hypospadias International Society (HIS) participated in an anonymous, 34-question online survey addressing pre-, intra-, and postoperative elements of HAPC evaluation and management. A selection of intraoperative photos were included in the survey to investigate the prevailing surgical approaches and identify management patterns.

RESULTS

Out of the 267 participants, 38.4% of them are located in Europe. Visual estimation was the predominant approach for evaluating HAPC, although being regarded as the least dependable compared to other techniques. Surgeons who performed more than 40 cases per year were more inclined to use goniometers and had varying degrees of HAPC that were considered acceptable without requiring any correction (P < .001). Out of 58% of respondents, a significant number reported regular utilization of artificial erection tests for all categories of hypospadias. Surgeons with fewer than 10 years of expertise commonly utilized erection test as part of their regular practice. A tourniquet was employed to maintain sufficient intra-corporeal pressure, by134 (50%). 116 participants (43%) inject Saline through the corpora cavernosa through the glans, while 150 (56%) administer saline from the lateral aspect. Moreover, the decision-making process differed based on the intraoperative picture scenarios of mild to moderate penile curvature during erection testing. Contrary to temperatures ranging from 25o to 35o, decision-making in cases with less severe degrees of HAPC was uncomplicated.

CONCLUSION

This survey reveals a wide range of surgical practice patterns in the assessment and management of HAPC. To our knowledge, this global survey of HAPC practice is the largest to date and could aid in developing new guidelines in pediatric urology. These findings may also provide a foundation for future prospective multinational studies.

Urologist validation of an artificial intelligence-based tool for automated estimation of penile curvature

INTRODUCTION

Severity of penile curvature (PC) is commonly used to select the optimal surgical intervention for hypospadias, either alone or in conjunction with other phenotypic characteristics. Despite this, current literature on the accuracy and precision of different PC measurement techniques in hypospadias patients remains limited.

PURPOSE

Assess the feasibility and validity of an artificial intelligence (AI)-based model for automatic measurement of PC.

MATERIAL AND METHODS

Seven 3D-printed penile models with variable degrees of ventral PC were used to evaluate and compare interobserver agreement in estimation of penile curvatures using various measurement techniques (including visual inspection, goniometer, manual estimation via a mobile application, and an AI-based angle estimation app. In addition, each participant was required to complete a questionnaire about their background and experience.

RESULTS

Thirty-five clinical practitioners participated in the study, including pediatric urologists, pediatric surgeons, and urologists. For each PC assessment method, time required, mean absolute error (MAE), and inter-rater agreement were assessed. For goniometer-based measurement, the lowest MAE achieved was derived from a model featuring 86° PC. When using either UVI (unaid visual inspection), mobile apps, or AI-based measurement, MAE was lowest when assessing a model with 88° PC, indicating that high-grade cases can be quantified more reliably. Indeed, MAE was highest when PC angle ranged between 40° and 58° for all the investigated measurement tools. In fact, among these methodologies, AI-based assessment achieved the lowest MAE and highest level of inter-class correlation, with an average measurement time of only 22 s.

CONCLUSION

AI-based PC measurement models are more practical and consistent than the alternative curvature assessment tools already available. The AI method described in this study could help surgeons and hypospadiology researchers to measure PC more accurately.

The Natural (non-invasive) Erection Test: Is it a reliable alternative to the artificial erection test?

AIM OF THE STUDY

To test the accuracy and reliability of the natural erection test (NET) as compared to the artificial erection test in assessing penile curvature in hypospadias.

MATERIALS AND METHODS

50 children underwent both natural and artificial erection tests intraoperatively between January 2020 and October 2021. These included 5 glandular, 26 distal, 9 proximal, and 10 perineal hypospadias patients with curvature. The mean follow up period was 20 months (range 16-37). Under anesthesia, the curvature was assessed before degloving, then after degloving using both the natural and the artificial erection test. The NET test was repeated after curvature correction (3 times per patient). The measurements were analyzed using paired t-test.

TECHNIQUE OF NATURAL ERECTION TEST

Two fingers of the left hand press just below the symphysis pubis to stop blood drainage from the penis and two fingers of the right hand massage the blood from the perineum distally into the penis until it becomes hard without tourniquet. The standard artificial erection test was performed using saline injected through a butterfly needle into the corporeal bodies without tourniquet. Photos were taken of both tests using the exact angle and angle of curvature was measured using Angle Meter App.

RESULTS

There was no statistically significant difference between both erection tests with a P value of 0.705. The Bland-Altman plot also showed that all studied children have a difference in their natural and artificial erection tests within the limits of agreements.

DISCUSSION

Erection is commonly induced using the artificial saline injected erection test first described by Gittes and less commonly using pharmaceutical erection test first described by Perovic. The severity of chordee apparent during artificial erection test varies with the amount of pressure used during injection. Also, it is difficult to place the tourniquet proximal enough to detect chordee at the base of the penis. It may be associated with hematoma formation, oedema, postoperative pain and the need for multiple punctures to assess the curvature before and after repair. Disadvantages of the pharmacological-induced erections in hypospadias include increased blood loss during erection, additional cost, and the need for a reversal agent. The natural erection test mimic the normal erection mechanism and may avoid all these potential disadvantages.

CONCLUSION

The study showed that the natural erection test is easy to perform, non-invasive, non-traumatic and can be repeated several times intraoperatively without the need of repeated puncturing of the corpora cavernosa and avoids the potential risks and complications of the artificial erection test.

What is the angle of a banana? The difficulty in reliable assessment of hypospadias chordee

INTRODUCTION

The degree of chordee associated with hypospadias impacts operative management. Unfortunately, poor inter-observer reliability in assessing chordee by multiple methods in vitro has been demonstrated. This variability may be related to the fact that chordee is not a discrete angle, but rather an arc-like curvature similar to that of a banana. On an attempt to improve this variability, we assessed the inter-rater reliability of a novel method of chordee measurement and compared it to measurements with a goniometer both in vitro and in vivo.

MATERIALS AND METHODS

In vitro assessment of curvature was performed using 5 bananas. In vivo chordee measurement was performed during 43 hypospadias repairs. On in vitro and in vivo cases, chordee was assessed independently by faculty and resident physicians. Angle assessment was performed in a standard manner with a goniometer and with a smartphone app using ruler measurements of the length and width of the arc (Summary Figure). The proximal and distal aspect of the arc to be measured was marked on the bananas, whereas the penile measurements were taken from the penoscrotal to the sub-coronal junctions.

RESULTS

In vitro banana assessment demonstrated strong intra- and inter-rater reliability for length (0.89 and 0.88, respectively) and width measurements (0.97 and 0.96). The calculated angle demonstrated an intra- and inter-rater reliability of 0.67 and 0.67. The banana goniometer/protractor measurements were weak with an intra-rater and inter-rater reliability of 0.33 and 0.21. With hypospadias chordee, the inter-rater reliability was strong for length and width measurements (0.95 and 0.94) and 0.48 for calculated angle. The inter-rater reliability of the goniometer angle was 0.96. Further assessment of inter-rater goniometer reliability was performed relative to degree of chordee as characterized by faculty. The inter-rater reliability for ≤15°, 16-30, and ≥30° was 0.68 (n = 20), 0.34 (n = 14), and 0.90 (n = 9), respectively. When the goniometer angle was classified as ≤15, 16-30, or ≥30° by one physician, it was classified outside of this range by the other physician 23%, 47%, and 25% of the time, respectively.

DISCUSSION

Our data demonstrate significant limitations of the goniometer for assessing chordee in vitro and in vivo. We were unable to demonstrate significant improvement in chordee assessment using arc length and width measurements to calculate radians.

CONCLUSIONS

Reliable and precise techniques for measuring hypospadias chordee remain elusive and draw into question the validity and usability of management algorithms employing discrete values.

Unaided visual assessment of ventral curvature during hypospadias repair is inferior to objective measurement using app goniometry

OBJECTIVE

Failure to perform artificial erection or objectively assess ventral curvature (VC) during primary hypospadias repair is an important reason for residual/ recurrent chordee. The present study compares the accuracy of unaided visual inspection (UVI) with objective VC assessment using smartphone application (app) goniometry.

METHODS

All patients who underwent primary hypospadias repair between January 2021 and September 2022 were included. Assistant surgeons were asked to grade the degree of VC on UVI (after degloving and an artificial erection test) into: none, mild (<30 degree), severe(>30 degree). Lateral profile photograph was taken and angle measurement was performed on an android mobile application (Angulus). Correlation was performed with both methods of assessment.

RESULTS

During this period a total of 210 patients were analyzed; VC was noted in 40/138 (29%) cases of distal and in 62/72 (86%) cases of proximal hypospadias. Erroneous visual inspection was noted in 41/210 (20%; 95% CI 14-25%) on UVI (15 erroneously marked none while 26 marked mild). Among those found to have chordee, UVI assessed 39/82 (47%) as severe while app goniometry assessed 65/97 (67%) as severe. There was significant relative risk of labelling severe chordee as a mild one by UVI: 1.4 (95%CI 1-1.8; p=0.01).

CONCLUSIONS

UVI was erroneous in 20% of cases. UVI was less accurate in differentiating severe chordee from mild one. In 60% patients UVI alone could have led to erroneous VC assessment and thus wrong selection of technique. Further studies are required to validate our findings and standardize VC measurement using an app goniometry.

A new method for measuring penile curvature based on digital images

INTRODUCTION AND OBJECTIVE

Accurate and objective assessment of penile curvature is considered a critical evaluation in patients with hypospadias, as it often determines if a 1 or 2-stage procedure should be done. Due to the ease of acquisition and reusability of digital images, more research is focused on digital images; however, the current method based on digital images is not an easily accurate and objective evaluation of penile curvature amongst surgeons. In scoliosis, the Cobb method is a standard method to quantify spinal curvature. Therefore, this study introduces a new accurate, and standardized method for measuring penile curvature based on the digital image concerning the Cobb method.

METHODS

Twenty-two subjects were randomly selected, including 11 pediatric urologists with experience in goniometry(professional group)and 11 non-pediatric urologists without experience in goniometry (non-professional group). A total of 9 two-dimensional images of penile curvatures from 10° to 90°were obtained and stored in the research project notebook. Subjects measured 9 digital images using the new method (fixed anatomical position method) and classical method (the angle created by the interception of two ideal lines, one passing along the proximal portion of the corpora and a second passing through the tip of the penis), respectively. Measurement error was calculated as the absolute difference between the true curvature and the subject estimation. A t-test was used to evaluate the significant differences between the methods.

RESULTS

A total of 22 subject measurement data were obtained. Mean errors using the new method ranged from 1.06° to 3.50°, compared to 3.84°to 11.83°for classical method. Mean errors were significantly lower (p < 0.05) when using the new method compared to the classical method. A subgroup comparing subjects with and without prior experience with goniometry showed a statistically significant difference only for the classical method when the penis curvature is 10-40°, the mean error range of the professional group was 7.8°-9.56°, compared to 10.34°-13.02°for nonprofessional group.

DISCUSSION

We emphasize the importance of penile curvature measurement and urgent need for an accurate measurement method, and then we focus on the new method compare with the previously described methods looking at mean errors and explain the reason that the new method why is accurate. Subsequently, we focus on explain the impact of experience measurement methods. Finally, the shortcomings of this paper and the prospective points are discussed:1) how to obtain more photos in practical situations; 2) using artificial intelligence methods for automatic marking of key points to achieve efficient measurement of penile curvature.

CONCLUSIONS

In this preliminary study, we demonstrated better penile curvature estimations using the new method compared to the classical methods currently used by pediatric urologists.

Automated measurement of penile curvature using deep learning-based novel quantification method

Objective

Develop a reliable, automated deep learning-based method for accurate measurement of penile curvature (PC) using 2-dimensional images.

Materials and methods

A set of nine 3D-printed models was used to generate a batch of 913 images of penile curvature (PC) with varying configurations (curvature range 18° to 86°). The penile region was initially localized and cropped using a YOLOv5 model, after which the shaft area was extracted using a UNet-based segmentation model. The penile shaft was then divided into three distinct predefined regions: the distal zone, curvature zone, and proximal zone. To measure PC, we identified four distinct locations on the shaft that reflected the mid-axes of proximal and distal segments, then trained an HRNet model to predict these landmarks and calculate curvature angle in both the 3D-printed models and masked segmented images derived from these. Finally, the optimized HRNet model was applied to quantify PC in medical images of real human patients and the accuracy of this novel method was determined.

Results

We obtained a mean absolute error (MAE) of angle measurement <5° for both penile model images and their derivative masks. For real patient images, AI prediction varied between 1.7° (for cases of ∼30° PC) and approximately 6° (for cases of 70° PC) compared with assessment by a clinical expert.

Discussion

This study demonstrates a novel approach to the automated, accurate measurement of PC that could significantly improve patient assessment by surgeons and hypospadiology researchers. This method may overcome current limitations encountered when applying conventional methods of measuring arc-type PC.

Pediatric urologists' confidence and accuracy in estimating penile curvature

BACKGROUND

Assessment and management of congenital penile curvature (PC) can be variable. Methods for correction of PC usually are dependent on degree of PC which is reliant on how degree is assessed. We sought to assess the confidence and accuracy of measuring PC and hence management using case-based examples.

METHODS

A survey was emailed to members of the Societies for Pediatric Urology. Demographic information, management strategies for PC, and self-reported confidence in measuring PC were assessed. A Likert scale measured self-confidence. Case scenarios were used to assess ability to measure PC and methods of correction. The cases consisted of three computer-generated penis model images with arc-type ventral curvature and one image of lateral curvature in an infant.

RESULTS

The response rate was 30% (108/355). The mean confidence score was 3.6 ± 0.8 (3-fairly confident; 4-very confident). In clinic, 89% of urologists used eyeball estimates to assess PC; 5% used both eyeball and goniometer. In the operating room, 71% used eyeball estimates, 8% used goniometer, and 16% used both. If sole decision-maker, urologists recommend surgical correction of PC over observation at median 30° (IQR 21-30°). At a median of 45°, there was a shift in corrective surgical preference from dorsal plication (DP) (IQR 30-54°) to ventral lengthening (IQR 34-60°). Urologists underestimated PC degree for all cases (summary table). For all cases, there was no association between years in practice or confidence level on estimated PC degree. In case 1, only 24% of urologists would correct a mean estimate of 23° PC; those who would correct had a higher mean PC estimate vs those who would not (28° vs 21°, p < 0.001). Case 2 and 4 had similar estimations and correction methods. In case 2, those who chose VL had a higher mean PC estimate vs those who did not (43° vs 37°, p < 0.01), but no estimate difference was seen for DP (p = 0.52). In case 4 with lateral PC, those who chose DP had a higher mean PC estimate vs those who did not (41° vs 33°, p = 0.049). Yet in case 3, there was no difference in PC estimate in urologists who chose VL vs not (57° vs 53°, p = 0.16).

CONCLUSIONS

A uniform underestimation of PC existed despite self-reported confidence in the ability to measure PC. An increasing willingness to perform surgical correction was demonstrated with a shift towards VL for ventral curvature and less so for lateral curvature as PC worsens.

Automated quantification of penile curvature using artificial intelligence

Objective

To develop and validate an artificial intelligence (AI)-based algorithm for capturing automated measurements of Penile curvature (PC) based on 2-dimensional images.

Materials and methods

Nine 3D-printed penile models with differing curvature angles (ranging from 18 to 88°) were used to compile a 900-image dataset featuring multiple camera positions, inclination angles, and background/lighting conditions. The proposed framework of PC angle estimation consisted of three stages: automatic penile area localization, shaft segmentation, and curvature angle estimation. The penile model images were captured using a smartphone camera and used to train and test a Yolov5 model that automatically cropped the penile area from each image. Next, an Unet-based segmentation model was trained, validated, and tested to segment the penile shaft, before a custom Hough-Transform-based angle estimation technique was used to evaluate degree of PC.

Results

The proposed framework displayed robust performance in cropping the penile area [mean average precision (mAP) 99.4%] and segmenting the shaft [Dice Similarity Coefficient (DSC) 98.4%]. Curvature angle estimation technique generally demonstrated excellent performance, with a mean absolute error (MAE) of just 8.5 when compared with ground truth curvature angles.

Conclusions

Considering current intra- and inter-surgeon variability of PC assessments, the framework reported here could significantly improve precision of PC measurements by surgeons and hypospadiology researchers.

How accurate is eyeball measurement of curvature? A tool for hypospadias surgery

INTRODUCTION

Correction of penile curvature or "chordee" is a major component in the management of hypospadias. Accurate assessment and management of penile curvature influence both short- and long-term outcomes of surgery.

AIM OF THE STUDY

The objective of this study is to investigate the accuracy of eyeball measurement and how does it compare to objective measurement by standard goniometry (SG) and smartphone app goniometry (AG).

MATERIALS AND METHODS

A Dropbox file request link was shared with paediatric urologists on various social media platforms requesting participants to upload a picture of their index finger showing what they thought 30 degrees of curvature look like using their proximal inter phalangeal joint as the point of maximal curvature., The images were assessed using SG to measure the angle of curvature. The images were also assessed using AG by the principal investigator, a physician, a scrub nurse and a paediatric urology consultant., Statistical analysis was performed using SPSS statistics software version 26 (Armonk, NY: IBM Corp). A one sample t-test and a one-way chi squared test were used to evaluate significant frequency differences. Pearson correlation was used to compare AG measurements to test intra- and inter-observer reliability and to compare AG measurements vs SG measurements. Assuming 5-degree variability in goniometer measurements and 2-degree difference between the sample and population, the number of participants needed was calculated to be 49.

RESULTS

Fifty-two responses were received.32.7% of respondents simulated 30° accurately (17/52). A significant proportion (23/52, 44.2%) overrepresented the degree of curvature and 23.1% (12/52) underrepresented it (p = 0.01). Compared with objective measures, eyeball estimates differed by an average of 10° ± 1.5 SE. Measurements obtained by AG were comparable to measures obtained by SG and showed excellent intra-observer and inter-observer correlation (R = 0.983, P < 0.001).

DISCUSSION

We demonstrated a significant discrepancy between eyeball assessment of curvature and objective measurements in a cohort of hypospadiologists. This can be very relevant to intraoperative decision making. The limitation of the study is the use of a simulated model rather than assessment of curvature in patients with hypospadias. Another limitation is the lack of standardization of the way the pictures were taken.

CONCLUSION

We demonstrated a tendency among hypospadiologists to overestimate or underestimate curvature by an average of 10° on eyeball assessment. The use of App Goniometry shows excellent interobserver reliability and is comparable to standard goniometry in curvature assessment.

Evaluation of penile curvature in patients with hypospadias; gaps in the current practice and future perspectives

BACKGROUND/PURPOSE

Penile curvature (PC) is a significant phenotypic anomaly associated with hypospadias that can affect hypospadias repair post-operative outcomes and impact on long-term quality of life as well as psychosexual wellbeing of affected patients. While several previous studies have attempted to define PC assessment criteria, there is still no accurate, reproducible, and reliable tool for quantifying severity. Our goal was to review the pros and cons of the current tools utilized for assessing the degree of PC in children, stressing on both strengths and limitations of each method.

METHODS

A wide and deliberate review of the literature discussing the assessment of PC in hypospadias patients was conducted. We also draw on relevant methods employed in adults with PC and Peyronie's disease where a greater breadth of studies has been conducted.

RESULTS

The appraisal outcomes combined with our recommendations were presented in a structured approach discussing the pre-, intra-, and post-operative evaluation of PC in patients with hypospadias. Critical appraisal of the evaluation tools in terms of availability, cost, objectivity, and potential reproducibility was presented.

CONCLUSION

This review reflects on current tools used for assessing the degree of PC in children, highlighting both strengths and limitations of each method. A wide variety of approaches are currently being practiced or investigated, with each method displaying particular utility and reliability characteristics. Several approaches are currently being explored with high potential to overcome the current difficulties encountered when measuring PC both in clinical practice and research studies.

Surgical management of primary severe hypospadias in children: an update focusing on penile curvature

Over the past two decades, assessment and treatment of associated curvature has emerged as a major issue in treating patients with proximal hypospadias. However, the cut-off for defining a curvature as clinically significant is still unclear, as not all patients are bothered by the same degree of curvature and, although the need for a method to assess the curvature objectively has been emphasized, no standard method yet exists. Curvature is multifactorial. The same degree of curvature can be due to any possible combination of skin and/or subcutaneous dartos tethering, a short urethral plate and an intrinsic corpora disproportion. Different strategies can be used to treat curvature, depending on the underlying cause, surgeon preferences, and the goals of the repair. In the past 10 years, use of urethral plate transection and ventral lengthening procedures has increased, although the lack of long-term follow-up data on ventral lengthening procedures suggests that the use of such procedures should be selective. Furthermore, straightening manoeuvres are influenced by the technique used for subsequent urethroplasty and, in turn, may influence the success rate of the urethroplasty. This Review provides a comprehensive overview of the major developments from the past 10 years in the management of severe proximal hypospadias in children.

Dorsal penile curvature and megameatus intact prepuce hypospadias: A common association in a rare variant of hypospadias

BACKGROUND

Megameatus intact prepuce (MIP) is a rare variant of hypospadias. Unlike the hooded ventrally absent prepuce in non-MIP hypospadias, the prepuce in MIP hypospadias is fully circumferential and intact. The distal urethra remains wide with a deep glanular groove. While ventral curvature is a common finding in non-MIP hypospadias, neither ventral nor dorsal penile curvature has been reported in MIP hypospadias.

OBJECTIVE

To assess the association of the MIP hypospadias variant with penile curvature.

STUDY DESIGN

We retrospectively reviewed the medical records of all children who underwent hypospadias repair and identified those who were documented as having the MIP variant of hypospadias and operated in our center from January 1998 to June 2020. The patients were considered as having MIP hypospadias if no hypospadias had been evident before circumcision, if a circumferential circumcision scar was present (instead of the inverted V-shaped scar in the ventral aspect of the penis following circumcision of the hooded prepuce associated with non-MIP hypospadias), and if there was a wide meatus. Penile curvature was diagnosed intraoperatively by an artificial erection test that uses saline solution for injection. Patients were considered surgical candidates if the degree of curvature was equal to or greater than 30°.

RESULTS

The study cohort consisted of 118 male children who were identified as having the MIP hypospadias variant according to the inclusion criteria. The median age at repair was 1.1 years (interquartile range 8 months to 1.6 years). Penile curvature was found in 29 children (24%), of whom 23 had dorsal curvatures (19%) and 6 had ventral curvatures (5%).

DISCUSSION

MIP hypospadias is associated with penile curvature, and more frequently with dorsal than ventral curvature. This study is retrospective and does now identify specific features of MIP associated with penile curvature. We encourage pediatric urologists to perform an artificial erection test intraoperatively in children with the MIP variant and repair associated curvatures.

CONCLUSIONS

A dorsal curvature was found in 19% of patients with a MIP variant of hypospadias, and most of them (86%) required ventral plication due to the severity of the curvature.

Challenging proximal hypospadias repairs: An evolution of technique for two stage repairs

INTRODUCTION

Proximal hypospadias repair remains challenging. Our approach to the first stage of two-stage proximal hypospadias repairs has evolved from using Byars' flaps to preputial inlay grafts in anatomically suitable cases and pedicled preputial flaps in more complex repairs. We reviewed our outcomes, hypothesizing that inlay grafts and pedicled preputial flaps were associated with lower complication risks than Byars' flaps.

STUDY DESIGN

A single institution, retrospective, cohort study of consecutive two-stage, primary, proximal hypospadias repairs performed from 2007 to 2017 was conducted. Patients with <6 months follow-up and incomplete operative reports were excluded. Risk of complications (fistula, dehiscence, diverticulum, meatal stenosis, stricture) were evaluated following urethroplasty and stratified by first-stage repair technique. As technique refinements have been made since 2012, comparisons between two temporal subgroups (those who underwent repair in 2007-2012 and in 2013-2017) were made.

RESULTS

78 of 127 patients met inclusion criteria. Overall complication rate was 47% (Summary Table). Median follow-up was 25.4 months (range 6.4-128.5 months) after urethroplasty. Pedicled preputial flaps (hazards ratio [HR] 0.30; 95% Confidence Interval [CI] 0.14-0.65) and inlay grafts (HR 0.32; 95% CI 0.11-0.95) were associated with lower complication risks compared to Byars' flaps (Summary Table). Median time to complication was significantly shorter for Byars' flaps (5.7 months) than for inlay grafts (40.6 months) and pedicled preputial flaps (79.2 months) by Kaplan Meier analysis. Temporal subgroup comparisons showed that overall complication rates decreased from 70% to 31% (p = 0.001), but differences in complication rates by first-stage technique were not statistically significant.

DISCUSSION

In our cohort, repairs with Byars' flaps had the highest complication rate, which is consistent with our observations that urethras tubularized from Byars' flaps lack appropriate backing and are hypermobile and irregular. To overcome these shortcomings, modifications were made to our approach to two-stage proximal hypospadias repairs with the use of inlay grafts and pedicled preputial flaps quilted to the underlying corporal bodies to optimize the stability of the urethral plate. Our preliminary results are promising.

CONCLUSION

Approach to the first stage of two-stage repairs affects outcomes. Pedicled preputial flaps and inlay grafts were associated with lower complication risks than Byars' flaps. Refinement of technique and patient selection may have resulted in fewer complications in the short term. However, long-term follow-up is needed.

Standardization of penile angle estimation with a semi-automated algorithm

INTRODUCTION

Penile curvature (PC) refers to an abnormal bending of the main longitudinal axis of the penis. It is frequently associated to hypospadias. To date, accurate and objective evaluation of PC is not easily reproducible amongst surgeons and there are no stablished protocols on how to measure PC in a standard way and in real-time to guide intraoperative decision making. For this reason, we want to present the results of creating a semi-automated algorithm to establish a reproducible and objective assessment of PC and propose it as a standard protocol for clinical applicability using inanimate 3-D penile models.

METHODS

This project consisted in two different phases. 1. Creation of an automated algorithm to estimate penile angle based on digital images. 2 Use of the algorithm to estimate penile angle on 3-D models and estimate interrater agreement using the algorithm. The algorithm was created to initially identify the geometrical centerline of the penile model to establish an automated output for angle estimation. 3-D printed penile models with known curvature angles ranging from 10 to 90° were used to test the algorithm (total of 9 penile models. These models were curved at one hinge as opposed to an arc type model. For each inanimate model, a set of 5 pictures were obtained from a lateral view at different camera angles (0⁰, 15⁰, 30⁰, 45⁰ and 60⁰) at a standard distance of 75 cm. Angle estimation using our designed PC algorithm was performed by a total of 10 different evaluators. Inter-rater reliability analysis in using the semiautomated algorithm was performed using the inter-class correlation coefficient (ICC) with two-way mixed effect model.

RESULTS

If the camera angle was greater than 30°, the absolute angle mean difference was greater than 10°. Camera angle with the smallest mean difference was at 0⁰ with a mean difference of 7.83°. Agreement between raters showed greater variability towards the higher camera angles. Nonetheless, a high degree of between evaluator reliability was found between the measurements at different camera angles. Single measures ICC ranges from .873 to .946, p-values were all <.0001.

CONCLUSION

Our results help standardize PC assessment using digital images and reduce subjectivity using an algorithm for PC estimation. Optimal camera position between 0⁰ to 30⁰ vertical from the penis gives the least variable and most accurate angle estimation. Future studies using algorithms will help define predictive PC cutoff values and evaluate postoperative outcomes.

Staged repair of proximal hypospadias: Reporting outcome of staged tubularized autograft repair (STAG)

INTRODUCTION

Proximal hypospadias (PPH) repair is a challenge. Dilemma exists whether to do it in single or staged repair. Staged repair is our adopted procedure which was recently modified by Snodgrass into staged tubularized autograft repair (STAG), in which attention was given to ventral straightening of the penis together with some other technical details. Herein, we report our experience with STAG in a cohort of primary posterior hypospadias.

PATIENTS AND METHODS

In the period from 2011 to 2018 we operated 43 primary posterior hypospadias. Two principal surgeons (HB, MY) and multiple assistants operate children the same way, and data are recorded in a prospectively designed data base. In all children, inner prepuce graft was utilized, when curvature is more than 30 degrees, plate transection with or without ventral corporotomies were adopted.

RESULTS

Forty-three children with PPH and ventral curvature more than 30 degrees underwent first stage with median age 12 months (6-132 IQR16). Penile curvature was corrected by plate transection in 27 children (62.8%), ventral corporotomies in 16 children (37.2%). Graft take was successful in 90.7%, 4 children needed revision of fibrotic graft. Second stage was completed in 37 children, success was 56.8%, 21.6% fistula, 24.3% glanular dehiscence. Overall success after third surgery to correct complications was 78.4%. In a mean follow up of 3.2 years, we had recurrence of curvature in 2 children taking success rate to 72.9%. No meatal stenosis, no diverticulum, no stricture, no urethral dehiscence was encountered. Cosmetic appearance was excellent in follow up.

CONCLUSION

STAG achieves proper straightening of the penis and allows for reconstruction of a good urethra, yet urethrocutaneous fistula and glanular dehiscence remain the main complications. Follow up is important to address results of ventral corporotomies.

TYPE OF STUDY

Therapeutic.

LEVEL OF EVIDENCE

Level IV case series with no comparison group.

Measurement accuracy of 3-Dimensional mapping technologies versus standard goniometry for angle assessment

BACKGROUND

A specific aspect of the hypospadias phenotype that may contribute to long-term outcomes is the presence of ventral penile curvature and the adequacy of its surgical correction. The current gold standard to assess this angle is intraoperative goniometry of an erect penis. 3-dimensional (3D) mapping technologies may overcome the limitations of these traditional methods through their combination of digital image and geometric replication to produce consistent 3D digital forms of a physical structure. The aim of this study is to evaluate the measurement accuracy and reliability of handheld 3D mapping technologies versus standard goniometry for angle assessment in a laboratory setting.

METHODS

Blocks with specified angles (10-45°) were printed using a Zortrax M200 3D printer (±0.2% accuracy). Following the completion of standardized training, blinded participants measured each block angle using a baseline digit goniometer. Additionally, complete digital models of the blocks were created using 3D mapping technologies. Structured light scanning was completed using an Artec Space Spider and Artec Studio 13. Traditional photogrammetry was completed using a Canon Eos Rebel T5i DSLR camera and Agisoft Metashape Pro. Photogrammetry with a 3D camera was completed using the VECTRA H1 and VECTRA Analysis Module. All 3D models were imported into the software Autodesk Inventor in which automated angle measurements through the central plane were obtained. Statistical analysis was performed to determine the accuracy, precision and reliability of each modality using SAS 9.4 software. The reliability of goniometry and each mapping technology was evaluated using two-way random effect models with absolute agreement.

RESULTS

Six 3D printed blocks were evaluated. 5 digital models per block were created using each of the 3 mapping technologies. Inter-rater reliability of goniometry was moderate (ICC 0.76, 95% CI 0.46, 0.92), whereas all mapping technologies demonstrated excellent test-retest reliability: structured light scanning (ICC 0.99; 95% CI 0.999, 0.999); traditional photogrammetry (0.99; 0.99, 0.99); 3D camera (0.99; 0.99, 0.99). Mean angle measurements and standard error for each angle and modality are provided in the table.

CONCLUSIONS

This study demonstrated excellent accuracy, precision and reliability of off-the-shelf, handheld 3D mapping technologies and moderate reliability for goniometry when applied to measurements of angulation in a laboratory setting. The described methods developed in the laboratory for optimization of angle analysis from 3D models are an important step toward reliable, reproducible phenotypic analysis of congenital genitourinary conditions in future intraoperative and database development applications.

Digital Pattern Recognition for the Identification and Classification of Hypospadias Using Artificial Intelligence vs Experienced Pediatric Urologist

OBJECTIVE

To improve hypospadias classification system, we hereby, show the use of machine learning/image recognition to increase objectivity of hypospadias recognition and classification. Hypospadias anatomical variables such as meatal location, quality of urethral plate, glans size, and ventral curvature have been identified as predictors for postoperative outcomes but there is still significant subjectivity between evaluators.

MATERIALS AND METHODS

A hypospadias image database with 1169 anonymized images (837 distal and 332 proximal) was used. Images were standardized (ventral aspect of the penis including the glans, shaft, and scrotum) and classified into distal or proximal and uploaded for training with TensorFlow. Data from the training were outputted to TensorBoard, to assess for the loss function. The model was then run on a set of 29 "Test" images randomly selected. Same set of images were distributed among expert clinicians in pediatric urology. Inter- and intrarater analyses were performed using Fleiss Kappa statistical analysis using the same 29 images shown to the algorithm.

RESULTS

After training with 627 images, detection accuracy was 60%. With1169 images, accuracy increased to 90%. Inter-rater analysis among expert pediatric urologists was k= 0.86 and intrarater 0.74. Image recognition model emulates the almost perfect inter-rater agreement between experts.

CONCLUSION

Our model emulates expert human classification of patients with distal/proximal hypospadias. Future applicability will be on standardizing the use of these technologies and their clinical applicability. The ability of using variables different than only anatomical will feed deep learning algorithms and possibly better assessments and predictions for surgical outcomes.

Ventral penile curvature estimation using an app

INTRODUCTION AND OBJECTIVE

The assessment of penile curvature is a key component of hypospadias surgery, as it often determines if a 1 or 2-stage procedure should be done. The objective of this study was to test the accuracy of penile curvature measurements using an App-based method among non-urologists.

METHODS

Lateral pictures of six plastic 3-dimensional penile models representing each decile of curvature from 20 to 70° were obtained and stored on the research project iPad. Each picture was labeled with a name (i.e. Jim). Non-urology medical professionals were recruited to estimate the curvature of the six pictures with an App-based method consisting of the Photoblend Pro App and 9 provided graded 2-dimensional penile curvature images (representing each decile of curvature from 10 to 90°). Curvature estimations were done by merging the picture of the 3-dimensional penile model with one of the 9 provided graded 2-dimensional penile curvature images inside the App in an iterative process until the penile model picture matched the graded image (see figure). A research associate taught the research subjects the App-based method and then the subjects were asked to estimate the ventral penile curvature of each of the six penile model pictures. Measurement error was calculated as the absolute difference in between the measured value and the true value for the 6 models. A comparison was then made with previous research where pediatric urologists used either a goniometer or unaided visual inspection (UVI) to measure the ventral curvature of the same plastic 3-dimensional penile models used for the pictures of this study.

RESULTS

Twenty-one subjects were recruited, and all completed the study. Mean errors using the App ranged from 1.9° to 7.1°, compared to 6.5°-15° for UVI and 4.4°-15.9° for goniometry. The median error for the App was 0° compared to 5-10° for both UVI and goniometry. Mean errors were significantly lower (p < 0.05) when using the app compared to UVI/goniometry for all except the 30° and 50° models. Assuming patients with VC ≤ 30° would have had a one stage repair versus a 2-stage repair if curvature was >30°, the number of measurements that could have resulted in the unintended operation was calculated. There was a statistically significant difference in number of potential unintended surgeries in between App (17%) versus UVI + Goniometer (37%) (p = 0.0133).

CONCLUSION

This pilot study demonstrated better penile curvature estimations using the App compared to the two most common methods currently used by pediatric urologists. Plastic models provide an avenue to test and compare penile curvature measurement techniques.