|Year : 2018 | Volume
| Issue : 3 | Page : 94-99
Paediatric urology: Emerging challenges
Felix Naegele, Josef Oswald
Department of Pediatric Urology, St. Vincent Hospital, Linz, Austria
|Date of Web Publication||24-Sep-2018|
Department of Pediatric Urology, St. Vincent Hospital, Linz
Source of Support: None, Conflict of Interest: None
Medical advancements in paediatric urology are moving at a rapid pace, understanding natural history in congenital malformation of the urinary tract in infancy has changed our diagnostic as well therapeutic approach. Additionally more efficient diagnostic options have evolved our therapeutic in particular surgical approach toward minimally invasive options in children. Interdisciplinary teamwork are the needs of the moment applies above all to children with complex congenital malformations such as disorders of sexual development, urethral valves, cloacal extrophy or complex congenital deformities of the upper urinary tract. This short summary give insights into the current diagnostic discussion as well minimal invasive concepts of most important disease patterns in paediatric urology.
Keywords: Disorders, endoscopy, paediatric urology
|How to cite this article:|
Naegele F, Oswald J. Paediatric urology: Emerging challenges. Hamdan Med J 2018;11:94-9
| Preface|| |
Originating from urology, paediatric urology represents a subdiscipline dealing with various forms of congenital and acquired disorders of the urinary tract in children. While adult urology often has to focus on ablative treatment strategies, therapeutic approaches in paediatric urology are mainly reconstructive. Functional impairments in an early stage of development most often do have a vast impact throughout the whole life. Organically, revealed as renal damage and ultimately failure and not less often psychologically, inasmuch as abnormal genitalia appearances and functional impairments such as incontinence are stigmatising. Since the early days in the 1950s, the patient population evolved from being limited to infants and children to including adolescents and young adults. Therefore, close collaboration with adult-orientated healthcare specialists became mandatory to promote continuity of care for a broad spectrum of patients. Furthermore, interdisciplinary cooperation with paediatric endocrinologists, paediatric nephrologists and paediatric general and plastic surgeons allowed for improvements in the care of children with the most complex congenital malformations such as disorders of sexual development (DSD), urethral valves, cloacal exstrophy or aphallia. Numerous technical advances such as flexible endoscopes, individualised microinstruments such as all-seeing needle MicroPerc® and chip-on-the-tip optics, allowing variable focusing, were needed to make minimally invasive diagnostic and therapeutic regimens possible and will remain of major interest in future. This review aims to give insights into the current diagnostic as well as therapeutic concepts of the most frequent disorders in paediatric urology.
| Hydronephrosis|| |
The term ‘hydronephrosis’ refers to a dilatation of the renal collecting system, diagnosed by ultrasound and caused by a wide range of underlying pathologies. With an incidence of 1%–5% of all pregnancies, antenatal hydronephrosis (ANH) is one of the most common pathological findings on prenatal ultrasound. If vesicoureteric reflux can be excluded, congenital renal obstruction has to be identified as it can harm the developing kidney. Impaired drainage at the ureteropelvic junction due to a dysplastic section is described as ‘intrinsic stenosis', while ‘extrinsic stenosis’ refers to an obstruction caused by a lower pole vessel, crossing the ureter at its joint with the renal pelvis, most common in older, symptomatic children. Additional dilation of the ureter indicates an impaired drainage at the ureterovesical junction. Pre- and neo-natal evaluation is challenging since the majority of ANH resolves spontaneously, thus aborting the indication for further follow-up. However, missing corrective surgery prior to the onset of symptoms often leads to irreversible renal damage. Currently, there are neither diagnostic tools nor imaging studies available to predict the definitive outcome of ANH. Various grading systems to estimate the severity of hydronephrosis are in use, with the Society for Fetal Urology (SFU) classification considered to be the standard of care since 1993. Since there was no consensus on the follow-up of mild and moderate hydronephrosis postnatally, anteroposterior renal pelvic diameter (APD) was later implemented into the decision-making process, recommending further follow-ups if APD exceeds 10 mm at any point in gestation. The SFU grading system showed to have a modest inter-rater reliability and a weak correlation between pre-natal and post-natal ultrasound findings. Consequently, Nguyen et al. proposed a new classification system of urinary tract dilation (UTD) which was published after a consensus meeting in 2014. This UTD classification system uses a 3-point system based on six different ultrasound observations stratifying patients into three risk categories. In addition to ultrasound isotope studies, in particular, the Tc-99m dimercaptosuccinic acid (DMSA) renal scintigraphy became an integral part in the diagnostic workup of hydronephrosis, providing information about the differential renal function (DRF) as well as the tracer washout in a defined time sequence. The indication for pyeloplasty mainly relies on sequential imaging, particularly on deteriorating DRF. It is generally accepted that a DRF below 40% or deterioration of more than 5% represents an indication for intervention. For pelvic-ureteric junction obstruction, the dismembered Anderson–Hynes pyeloplasty with – if present – reallocation of crossing vessels to the posterior aspect of the pelvic-ureteric junction remains the gold standard, with success rates as high as 98%. In older children, laparoscopic or robotic surgery may be an option, while in small children, the open retroperitoneal access through a small incision remains to be superior.
| Vesicoureteral Reflux|| |
In Europe and Northern America, the incidence of vesicoureteral reflux (VUR) ranges from 1% to 3% in healthy children. If diagnostics are performed in a cohort who suffered from febrile urinary tract infection (fUTI), VUR can be found in 35%–50% of cases., VUR leads to urinary tract infection (UTIs) and ultimately to renal scarring after pyelonephritis; however, while some clinically relevant VURs tend to disappear and become purportless, the risk of kidney scarring does not decline, indicating that acquired and thus preventable kidney damage is a direct consequence of UTI. Thus, management of VUR remains complex, since identifying patients who would profit from surgical intervention versus those with low morbidity is still demanding. In groundbreaking studies, it could be shown very convincingly, however, that kidneys do not outgrow the risk of scarring in case VUR is not treated and eventually leads to subsequent UTIs. The challenge in the management of VUR, therefore, lies in early and correctly identifying those children that would profit from a surgical intervention as opposed to those carrying a low risk for further UTIs or consecutive renal damage. Classically, there are two approaches for further evaluation after fUTIs. In the ‘bottom-up approach', an initial voiding cystourethrography (VCUG) is performed to identify VUR – if present – followed by a DMSA scan to screen for kidney involvement. Since only 30% of those initial VCUGs are positive, a lot of children are undergoing unnecessary diagnostic procedures including radiation burden and discomfort. In the ‘top-down’ approach, DMSA scan is performed first and can be a valid alternative in view of the fact that in primary diagnostics DMSA results correlate very well with reflux grades on VCUG as well as with the risk for breakthrough infections and further kidney damage, allowing for a risk stratification of VUR patients. Therefore, many experts in the field advocate the importance of an initial DMSA scan ('top-down approach') to reliably detect the children at greatest risk for kidney damage and avoid overtreatment of low-grade VUR., Another option of the conventional VCUG would be the contrast-enhanced voiding sonography (CEVS) using the ultrasound contrast agent SonoVue® (sulfur hexafluoride microbubbles, Bracco Imaging, Milan), [Figure 1]. With the use of specialised imaging tools (subtractive imaging and colour enhancement) on adapted ultrasound machines with very low emission power/low frequency, highly sensitive diagnosis of VUR is feasible. Given a state-of-the-art equipment and sufficient experience of the examiner, CEVS has been shown to be even more sensitive compared to conventional VCUG. The importance of not missing out on the presence of (minor) posterior urethral valves in boys should be emphasised. Whereas in most major valves, radiological depiction of the urethra might prove helpful in indicating an endoscopic evaluation and treatment; in minor forms, its sensitivity is limited. Therefore, possible indirect signs of subvesical obstruction, as for instance a hypertrophied internal sphincter, a trabeculated appearance of the bladder floor, a dilated prostatic urethra or an irregular aspect of the urethra, should be taken very seriously. Furthermore, in boys with a combination of (usually high grade) VUR into at least one kidney and a smaller (or not present) kidney – a ‘syndrome' firstly described by Hoover and Duckett in 1982 – a suspicion should be raised. A justified suspicion should lead to further, endoscopic diagnostics in any case.
|Figure 1: Contrast-enhanced voiding sonography demonstrating VUR in a double system with ureter fissus (right)|
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Positioning irrigation of contrast (PIC) cystography is an additional diagnostic tool to identify the so-called ‘occult’ VUR, which cannot be diagnosed by any conventional method of VCUG. In more than half of the children who have had a febrile UTI, VCUG shows no VUR. Some, however, either have suggestive DMSA alterations or further UTIs. In an attempt to prevent recurrence of UTIs as well as renal damage, some surgeons have performed open surgical antireflux procedures in such patients and observed a significant post-operative reduction in febrile UTI recurrences,, pointing at the possibility of some VUR not diagnosed initially. In 2003, Rubenstein et al. reported their pilot study of the PIC cystography, which uses the contrast irrigation jet of the cystoscope. Over 50% of children with a history of febrile UTIs do have a negative VCUG. Some, however, either have suggestive DMSA alterations or further UTIs. Performing antireflux procedures showed to be beneficial for patients with these ‘occult’ VURs.,, Concepts of surgical antirefluxive re-implantation of the ureters gained popularity as early as in the 1960s of the last century. Minimally invasive therapeutic concepts such as endoscopic reflux therapy (ET) could be introduced in the 1980s as a consequence of better understanding in the pathophysiology of renal damage and subsequent UTIs. However, the efficacy of ET is hampered by up to 26% late recurrences 1–2 years after therapy of high-grade VUR. For high-risk patients with dilating VUR or marked post-pyelonephritic changes on DMSA scans, open ureteral re-implantation remains the risk-adapted, standard treatment, with Cohen's cross-trigonal re-implantation being the most commonly used technique.,
| Bladder Exstrophy and Epispadias|| |
With a rate of 1:10.000–1:50.000 live births, bladder development fails, causing an abnormality described as classical exstrophy, where the bladder is an open plate outside the abdomen. Since this defect causes herniation of posteriorly developing structures, the anterior part of the pelvis cannot fuse, resulting in a wide diastasis of the symphysis pubis, corpora cavernosa and splayed glans in boys, as well as an open urethral plate and therefore is referred to as exstrophy–epispadias complex. The goal of treatment includes the cosmetically appealing closure of the bladder, urethra and lower anterior abdominal wall, while achievement of sufficient bladder capacity, urinary continence and reconstruction of the penis is intended [Figure 2]. In 1992, Grady and Mitchell described the complete repair of classic bladder exstrophy with bladder closure and epispadias repair at birth. The majority of paediatric urologists prefer some kind of staged approach to exstrophy reconstruction (modern staged exstrophy repair) which involves bladder closure shortly after birth, followed by epispadias repair after 6–12 months and bladder neck reconstruction before the age of 6., Pelvic osteotomy remains to be important even in older patients; it reduces the pubic diastasis and restores the pelvic ring and floor to the normal anatomical configuration. However, there is a debate about the necessity of osteotomies for bladder extrophy closure. The radical soft-tissue technique (Kelly technique) has been proposed as an alternative for staged reconstruction of bladder exstrophy. Usually performed at the age between 9 and 12 months without osteotomy, it involves simultaneous intrapelvic and perineal dissection and mobilisation of the periosteum from the pubic symphysis to Alcock's canal, allowing the soft tissues of the bladder, bladder neck and urethra to be approximated in the midline. Due to the complex dissection during radical mobilisation, potential complications such as an injury of the pelvic structures as well as penile tissue arise. Epispadias repair is performed by the modified Cantwell–Ransley repair involving the partial penile disassembly technique with in situ neourethroplasty and glanduloplasty [Figure 3]. Originally, the corpora were rotated medially above the urethroplasty, creating a proximal cavern-cavernostomy, often causing the penis to be shortened and dorsally bent. Avoiding this potential dorsal flexion corpora could be achieved by derotation and fixation beyond the neourethra [Figure 4]. All of the above-described surgical techniques have shown to be suitable procedures; all equally limited by similar complications such as fistula formations, wound dehiscence, bladder outlet obstruction and genital injury. The single-most relevant parameter in exstrophy repair is achieving continence. If the primary closure fails, augmentation, cystoplasty or bladder neck transection with continent urinary diversion is necessary to achieve dryness.
|Figure 2: Bladder neck reconstruction achieving continence in staged bladder extrophy closure|
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|Figure 3: Corpora preparation avoiding any damage of the lateral running neurovascular bundle. Dorsal aspect after tubularisation of the urethral plate (right image)|
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|Figure 4: External rotation of the corpora results in a more physiological deflection of the penis|
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| Hypospadias|| |
With an incidence of 1 in 200 live born males, hypospadias is one of the most common congenital disorders. There have been efforts to diagnose hypospadias with antenatal ultrasonography and magnetic resonance imaging, but in general, hypospadias is diagnosed upon examination of the newborn. More severe forms of hypospadias tend to have a higher incidence of undescended testes (UDTs), indicating a possible DSD. Conventionally, hypospadias is classified according to the position of the meatus (distal and proximal). Depending on the severity, indication for surgical repair far outreaches only cosmetic appearance: functional as well as psychological long-term effects have to be taken into account. Patients with minor hypospadias are at very low risk of suffering from adverse effects, making it challenging to find distinct criteria to indicate surgical intervention. In general, the goals of surgical treatment are orthoplasty (straightening), urethroplasty (meatus at the tip of the penis), glansplasty, penile skin coverage and a normal-appearing scrotum. Historically, hypospadias repair was performed after 3 years, which is technically easier due to the penile size. Nowadays, surgery is done in children aged between 4 and 18 months since studies have shown an improved psychological result and potentially better wound healing, possibly associated with a reduced cytokine production at an earlier stage in life. Further, over all complication rates – especially urethrocutaneous fistula occurring in up to 50%, especially in proximal hypospadias tend to be lower in infancy. One-stage repairs involve correction of the curvature and urethral reconstruction at the same time, while multistaged repairs address different steps in multiple sittings [Figure 5]. Both increasing the layers of tissue between the urethra and skin and the usage of urethral stents adjunct to hypospadias could reduce the rate of fistula., At the same time, the usage of stents bears the risk of irritative symptoms and UTIs.
|Figure 5: Scrotal hypospadias with bifid scrotum. After degloving, chorda resection and urethral transection (Bracka I, right image), Urethral tubularisation (Bracka II, far right in the picture)|
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| Undescended Testis|| |
One of the most common diagnoses in paediatric urology is UDT affecting 1% of full-term infants at the age of 1 year. It is defined as a testis that has failed to descend to a scrotal position until birth. Cryptorchidism can be classified as palpable or non-palpable, with the consequent indication to a primary open access to the inguinal region versus a diagnostic respective laparoscopic access to the assumed abdominal testis [Figure 6]. If sonography is added to the diagnostic workup, the prediction accuracy is increased, for example, contralateral testis size has been shown to have a sensitivity up to 90%. Additional inguinal ultrasound of non-palpable testes with measurement of the contralateral testis are synergistic in predicting the surgical approach, avoiding unnecessary diagnostic laparoscopies which reduces costs as well as the invasiveness of surgery. Inguinal orchidopexy, usually an outpatient surgery, should be performed until the 1st birthday. In high inguinal testes, a Prentiss manoeuvre or a vascular dissection, either open or laparoscopically is necessary. Further, ligation of the spermatic vessels proximal to the testis-single or two staged (Fowler–Stephens operation) - or close to the testis especially in cases with a long deferens loop (Koff–Sethi technique) should be considered.,
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