Đề ôn thi thử môn hóa (16)

9  The Decision to Initiate Dialysis in Children and Adolescents
Study on the Adequacy of Dialysis (NECOSAD)-2.
J Am Soc Nephrol. 2004;15(4):1061–70.
127.Paniagua R, Amato D, Vonesh E, Correa-Rotter R,
Ramos A, Moran J, et al. Effects of increased peritoneal clearances on mortality rates in peritoneal
dialysis: ADEMEX, a prospective, randomized, controlled trial. J Am Soc Nephrol. 2002;13(5):1307–20.

128.
Rottembourg J.  Residual renal function and
recovery of renal function in patients treated by
CAPD. Kidney Int. 1993;40:S106–10.

129.
Lang SM, Bergner A, Topfer M, Schiffl
H. Preservation of residual renal function in dialysis
patients: effects of dialysis-technique-related factors. Perit Dial Int. 2001;21(1):52–7.
130.Schulman G.  The role of hemodialysis and peritoneal dialysis for the early initiation of dialysis.
Blood Purif. 2001;19(2):175–8.
131.Feber J, Scharer K, Schaefer F, Mikova M, Janda
J. Residual renal function in children on haemodialysis and peritoneal dialysis therapy. Pediatr Nephrol.
1994;8(5):579–83.

132.Fischbach M, Terzic J, Menouer S, Soulami K,
Dangelser C, Helmstetter A, et  al. Effects of automated peritoneal dialysis on residual daily urinary
volume in children. Adv Perit Dial. 2001;17:269–73.
133.Hufnagel G, Michel C, Queffeulou G, Skhiri H,
Damieri H, Mignon F.  The influence of automated peritoneal dialysis on the decrease in
residual renal function. Nephrol Dial Transplant.
1999;14(5):1224–8.

134.Hiroshige K, Yuu K, Soejima M, Takasugi M,

Kuroiwa A. Rapid decline of residual renal function
in patients on automated peritoneal dialysis. Perit
Dial Int. 1996;16(3):307–15.
135. de Fijter CW, ter Wee PM, Donker AJ. The influence
of automated peritoneal dialysis on the decrease in
residual renal function. Nephrol Dial Transplant.
2000;15(7):1094–6.
136.McDonald SP, Craig JC.  Australian, New Zealand
Paediatric Nephrology A.  Long-term survival of
children with end-stage renal disease. N Engl J Med.
2004;350(26):2654–62.

137.Chesnaye NC, van Stralen KJ, Bonthuis M,
Harambat J, Groothoff JW, Jager KJ.  Survival in
children requiring chronic renal replacement therapy. Pediatr Nephrol. 2018;33(4):585–94.
138.Weaver DJ Jr, Somers MJG, Martz K, Mitsnefes
MM.  Clinical outcomes and survival in pediatric patients initiating chronic dialysis: a report
of the NAPRTCS registry. Pediatr Nephrol.
2017;32(12):2319–30.

129


139.Litwin M, Grenda R, Prokurat S, Abuauba M,
Latoszynska J, Jobs K, et  al. Patient survival and
causes of death on hemodialysis and peritoneal
dialysis--single-center study. Pediatr Nephrol.
2001;16(12):996–1001.
140.Fenton SS, Schaubel DE, Desmeules M, Morrison
HI, Mao Y, Copleston P, et al. Hemodialysis versus

peritoneal dialysis: a comparison of adjusted mortality rates. Am J Kidney Dis. 1997;30(3):334–42.
141.Collins AJ, Hao W, Xia H, Ebben JP, Everson SE,
Constantini EG, et  al. Mortality risks of peritoneal dialysis and hemodialysis. Am J Kidney Dis.
1999;34(6):1065–74.
142.Coles GA, Williams JD. What is the place of peritoneal dialysis in the integrated treatment of renal
failure? Kidney Int. 1998;54(6):2234–40.
143.Alloatti S, Manes M, Paternoster G, Gaiter AM,
Molino A, Rosati C.  Peritoneal dialysis compared
with hemodialysis in the treatment of end-stage
renal disease. J Nephrol. 2000;13(5):331–42.
144.Davies SJ, Phillips L, Griffiths AM, Russell LH,
Naish PF, Russell GI. What really happens to people on long-term peritoneal dialysis? Kidney Int.
1998;54(6):2207–17.
145.Wang T, Heimburger O, Waniewski J, Bergstrom
J, Lindholm B.  Increased peritoneal permeability
is associated with decreased fluid and small-solute
removal and higher mortality in CAPD patients.
Nephrol Dial Transplant. 1998;13(5):1242–9.
146.Schaefer F, Klaus G, Mehls O. Peritoneal transport
properties and dialysis dose affect growth and nutritional status in children on chronic peritoneal dialysis.
Mid-European Pediatric Peritoneal Dialysis Study
Group. J Am Soc Nephrol. 1999;10(8):1786–92.
147.Maiorca R, Vonesh E, Cancarini GC, Cantaluppi A,
Manili L, Brunori G, et  al. A six-year comparison
of patient and technique survivals in CAPD and
HD. Kidney Int. 1988;34(4):518–24.
148.Vonesh EF, Moran J.  Mortality in end-stage renal
disease: a reassessment of differences between
patients treated with hemodialysis and peritoneal
dialysis. J Am Soc Nephrol. 1999;10(2):354–65.

149.Tanna MM, Vonesh EF, Korbet SM. Patient survival
among incident peritoneal dialysis and hemodialysis patients in an urban setting. Am J Kidney Dis.
2000;36(6):1175–82.

150.Al-Hermi BE, Al-Saran K, Secker D, Geary
DF.  Hemodialysis for end-stage renal disease in
children weighing less than 10 kg. Pediatr Nephrol.
1999;13(5):401–3.


Urological Issues
in Pediatric Dialysis

10

Joshua D. Chamberlin, Angus Alexander,
Armando J. Lorenzo, and Antoine E. Khoury

Abbreviations

Introduction

CIC
CKD
ESKD
FSGS
LUT
PBS
PD
PUV

UTI
VCUG
VUR

The prevalence of end-stage kidney disease
(ESKD) in the pediatric population is approximately 50 cases per million, while 4 cases per
million receive renal replacement therapy [1].
While the etiology of ESKD remains consistent
across time, the prevalence of ESKD has been
increasing across all pediatric age groups, particularly among older children [2, 3]. In contrast
to adults, where glomerulopathy and vasculopathy are the major causes of kidney disease, at
least 40% of the chronic kidney disease (CKD) in
children is due to congenital urological abnormalities [4–8]. As a result, the urologist is an
essential member in any team managing pediatric
CKD.  Similarly, all providers of children with
CKD benefit from understanding these urological
management principles.
This chapter will review the common urological conditions that cause kidney failure in children, the diagnosis and pathophysiology of these
conditions, and an overview of the urologic management. As dialysis represents the treatment
phase during CKD between the development of
ESKD and kidney transplantation, this chapter
will discuss issues present prior to the initiation
of dialysis and following kidney transplantation.
Also, unique implications for pediatric dialysis
and kidney transplantation will be addressed,
including urology specific pretransplant evaluation and indications for nephrectomy in the CKD
patient.

Clean intermittent catheterization
Chronic kidney disease

End-stage kidney disease
Focal segmental glomerulosclerosis
Lower urinary tract
Prune belly syndrome
Peritoneal dialysis
Posterior urethral valves
Urinary tract infection
Voiding cystourethrogram
Vesicoureteral reflux

J. D. Chamberlin
Department of Urology, Loma Linda University,
Loma Linda, CA, USA
Department of Urology, Loma Linda University
Children’s Hospital, Loma Linda, CA, USA
A. Alexander
Department of Paediatric Surgery, The Children’s
Hospital at Westmead, Sydney, NSW, Australia
A. J. Lorenzo
Department of Surgery, Hospital for Sick Children,
Toronto, ON, Canada
A. E. Khoury (*)
Department of Urology, University of California,
Irvine, Orange, CA, USA
Department of Urology, Children’s Hospital of
Orange County, Orange, CA, USA
e-mail:

© Springer Nature Switzerland AG 2021
B. A. Warady et al. (eds.), Pediatric Dialysis, />

131


J. D. Chamberlin et al.

132

 rological Causes of Chronic Kidney
U
Disease
The causes of CKD in children may be categorized into congenital and acquired conditions and
are listed by anatomical location in Table 10.1 [6,
9–18]. Select significant causes are italicized and
are the focus of the chapter.

Posterior Urethral Valves
Posterior urethral valves (PUV) are abnormal
membranous folds unique to the male prostatic urethra. While there are other rare causes of congenital
Table 10.1  Urological causes of chronic kidney disease
in children, italicized are discussed in this chapter
Congenital

Acquired

a

Causes
Renal dysplasia
Ureteropelvic junction obstruction
Ureterovesical junction obstruction

Ureteroceles
Vesicoureteral reflux
Neurogenic bladder
Posterior urethral valves
Prune belly syndrome
Obstructing urolithiasis
Obstructing neoplasms
Neurogenic bladder
Urethral strictures

lower urinary tract (LUT) obstruction, such as urethral atresia and obstructive ureteroceles, PUV are
undoubtedly the most common. They are encountered in 1 of 5000–25,000 live births [19–22].
Advances in antenatal diagnosis, improved
perinatal medicine, and early PUV management
have led to a decrease in the neonatal mortality
rate associated with PUV.  In spite of these
advances and antenatal intervention, there has
been little improvement in the proportion of these
patients ultimately developing CKD [23]. Twenty
to sixty percent of boys with PUV will manifest
with evidence of CKD in childhood, and 11–51%
will eventually progress to ESKD during long-­
term follow-up [24–27].
Increasingly, the diagnosis is suggested in the
antenatal period with ultrasound findings of oligohydramnios, bilateral hydroureteronephrosis, a
thickened bladder wall, and a dilated posterior
urethra (Fig.  10.1). Children without a prenatal
diagnosis will present at different ages in the postnatal period with a variety of conditions, including respiratory insufficiency, kidney failure,
urosepsis, failure to thrive, poor urinary stream,
and urinary incontinence. The variation of PUV

presentations represents a spectrum of disease, in
which less severe forms of obstruction are often
detected later in life and may be associated with a
smaller impact on overall kidney function.
b

Fig. 10.1  Sonographic features suggestive of PUV detected during antenatal evaluation: (a) thick-walled bladder with
prominent posterior urethra, the “key-hole” sign; (b) high-grade hydronephrosis


10  Urological Issues in Pediatric Dialysis

To prevent or attenuate kidney damage that
occurs in utero, prenatal interventions have
sought to bypass the urethral obstruction with
open diversion, percutaneous diversion, or more
recently cystoscopy of the fetal urinary system
[28–30]. The decision to attempt antenatal intervention should be guided by selective criteria,
aided by the analysis of amniotic fluid levels,
imaging of renal dysplasia, and fetal urinary
markers (sodium, chloride, osmolality, and B2-­
microglobulin) [31]. Vesicoamniotic shunting
achieves the required supra-urethral diversion
while being minimally invasive, obviating the
need for a maternal hysterotomy and fetal vesicostomy. Interventions to preserve kidney function would need to be performed early, probably
before 22–23 weeks of gestation, although this is
not well established [32]. Antenatal interventions
are associated with a fetal mortality rate that
ranges from 33% to 43%. Not all the reported
deaths are directly related to the intervention, as

many deaths recorded may be secondary to ensuing pulmonary hypoplasia. These procedures are
also associated with significant morbidity in the
form of urinary ascites, visceral herniation, shunt
malfunction, and shunt migration [33–36].
Regardless of the timing of the postnatal presentation, an ultrasound of the kidneys, ureter,
and bladder should be the first imaging study
obtained. The ultrasound will often demonstrate
a thick-wall bladder with a prominent posterior
urethra, the “key-hole” sign, and high-grade
hydroureteronephrosis. A voiding cystourethrogram (VCUG) is indicated to confirm the diagnosis of PUV. Typical features on VCUG include a
dilated posterior urethra with a clear sharp transition to a normal (or attenuated due to reduced
flow) distal channel, an associated valve cusp, a
thickened open bladder neck, and a trabeculated
bladder. Vesicoureteral reflux (VUR) is also often
present (Fig. 10.2). While not always predictive
of a favorable prognosis, the presence of a urinary “pop-off” has been reported to be protective
in some children, by protecting at least one functioning kidney. Such “pop-off” mechanisms
include unilateral high-grade VUR into an ipsilateral dysplastic/nonfunctioning kidney, a bladder diverticulum, a perinephric urinoma, urinary
ascites, and a patent urachus [37–42].

133

Fig. 10.2  Features of PUV on VCUG: dilated posterior
urethra (white arrow) with a change in caliber compared
with the anterior urethra at the site of the valves (blue
arrow). Associated bilateral vesicoureteral reflux
(asterisk)

At birth, many boys with PUV will have preexisting renal dysplasia and will eventually
develop CKD regardless of treatment. An important goal of PUV management is to delay the

onset of kidney failure, by optimizing function of
the kidneys, ureters, bladder, and urethra.
Management is initially directed at systemic stabilization and decompression of the urinary tract.
Initial urological instrumentation usually
involves urethral catheterization in the early neonatal period, prior to the confirmation of the diagnosis. The simple intervention of urethral
catheterization temporarily bypasses the urinary
obstruction, allows accurate monitoring of urine
output, and helps avoid emergent surgical intervention, while associated abnormalities are identified and their management optimized. A VCUG
can then be obtained by instilling contrast through
the catheter with subsequent catheter removal to


J. D. Chamberlin et al.

134

image the urethra. Subsequent definitive urethroscopic valve ablation can be performed in most
boys, except for the smallest of infants. Premature
or small infants, whose urethras will not accommodate a cystoscope, are candidates for alternative forms of decompression. Similarly, in the
occasional scenario, where valve ablation does
not achieve decompression of the upper tracts,
surgical diversion above the bladder outlet warrants consideration. This may be in part due to a
functional ureterovesical junction obstruction as
the ureter passes through a markedly thickened
detrusor muscle. In such situations, segments of
the urinary tract can be temporarily brought to
the skin, in the form of a vesicostomy, ureterostomy, or pyelostomy (Fig. 10.3).
Bacterial colonization of the prepuce of uncircumcised boys predisposes them to urinary tract
infection (UTI), particularly in the first year of
life. Circumcision should be considered at the

time of the valve ablation or vesicostomy to significantly decrease the risk of UTI [43]. This
intervention is often heavily influenced by cultural and religious expectations.
Following valve ablation, the obstructive process is usually relieved; however, the functional
improvements are less predictable. Urodynamic
findings in these boys remain highly variable and
prone to change over time, as kidney function,
growth, and the acquisition of continence further
challenge the stability of the bladder [44, 45].
a

b

The primary goal of the urological management
in PUV is the preservation of upper tract function, which is achieved by ensuring an infection-­
free urinary tract with a bladder that stores urine
at low pressure and empties efficiently. The secondary goals include urinary continence and a
safe lower tract for those that require kidney
transplantation.
Poorly controlled lower urinary tract (LUT)
dysfunction can adversely affect existing kidney function. Residual bladder dysfunction in
PUV is an independent risk factor for CKD [12,
25]. In 1980, Mitchell coined the term “valve
bladder syndrome,” identifying deleterious features of lower tract dysfunction that could reliably predict kidney deterioration. This term
describes the development or persistence of
hydroureteronephrosis in the presence of a
poorly compliant, thick-walled bladder, incontinence, and polyuria [46].
Koff further clarified the role of the bladder in
the deterioration of the upper tracts, suggesting
that polyuria, insensitivity to overdistension, and
high post void residual volumes were the three

key factors contributing to kidney deterioration
in valve patients [47].
An overwhelmed bladder with borderline
function may lead to upper tract damage.
Polyuria, caused by nephrogenic diabetes insipidus, has the potential to overload the bladder of
the most diligent voider. Insensitivity to overdisc

Fig. 10.3  Appearance on physical examination of different forms of cutaneous urinary diversion: (a) vesicostomy, (b)
distal ureterostomy, and (c) bilateral pyelostomies (patient prone)


10  Urological Issues in Pediatric Dialysis

135

tension contributes to the potential for bladder
overload and injury. High post void residual volumes decrease the functional capacity of the
bladder and are not necessarily the result of myogenic failure [48]. Pseudo-residual volumes can
be seen in children with PUV and VUR when
urine refluxes into dilated ureters during filling
and voiding, only to empty back into the bladder
immediately after voiding. An additional cause of
pseudo-residual volumes is a hypertrophied
detrusor muscle that creates a functional ureterovesical junction obstruction during bladder filling, which is relieved after voiding, allowing the
retained urine to drain from the dilated ureters
(Fig. 10.4) [49].
With this understanding, hydroureteronephrosis is no longer considered unavoidable in PUV
patients. Management has become proactive,
focused on achieving complete urinary tract emptying (double voiding, timed voiding, and clean
Fig. 10.4  Issues to

consider in the
monitoring of patients
with PUV. Adequately
addressing these
problems helps prevent
or slow kidney
deterioration and
provides a conceptual
framework upon which
to consider interventions
and tailor treatment

intermittent catheterization [CIC]), optimizing
detrusor function (with judicious use of anticholinergics), and the selective use of alpha-blockers
to assist voiding [50]. On occasion, routine daytime interventions are unsuccessful at preventing
hydronephrosis in PUV, due to the polyuria and
decreased functional capacity. To overcome this,
nocturnal CIC or overnight indwelling catheterization has been shown to reduce diuresis,
decrease the incidence of UTI, improve urinary
continence, and decrease upper tract dilation [47,
51, 52].
VUR in PUV children is found in 50–70% of
patients and is usually secondary to the obstructed
bladder outlet [53, 54]. Because of its association
with worse renal dysplasia, high-grade reflux can
predict higher morbidity and mortality [55, 56].
Adequate treatment of the valvular obstruction
will lead to spontaneous resolution of VUR in
most cases (62%), and therefore VUR should be

VUR

DIABETES
INSIPIDUS

URETHRAL
OBSTRUCTION

POLYURIA

HIGH
RESIDUAL
VOLUMES

DECREASED
FUNCTIONAL
RESIDUAL
CAPACITY

R
E
N
A
L
INSENSITIVITY
TO DISTENSION

RENAL
DYSPLASIA
MYOGENIC

FAILURE

INFECTION

D
A
M
A
G
E