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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5795_Библиотеки_им_академика_М_И_Перельмана.pdf
15 Ultrasound oftheUrogenital Tract inNeonates, Infants, andChildren
Fig. 15.15 Hereditary/genetic cystic renal disease: ARPKD, ADPKD, nephronophthisis. (a)
ARPKD—bilaterally enlarged kidney, in neonates microcysts often not visible by US, some patchy
“pepper and salt” appearances of hyperechoic parenchyma. (b) ADPKD—bilateral (groups of)
single cysts of different size (child with known familiar cystic kidney disease). (c) Syndromatous
cystic renal disease—unspecic cysts in both kidneys in a neonate. (d) Nephronophthisis—girl
with end-stage renal failure due to nephronophthisis. Observe the typical parenchymal, radialgrouped cysts seen in late stage of disease
391
Non-genetic congenital cystic disease: often associated with urinary tract
obstruction or high-grade VUR (see dysplasia), rarely familial.
• Multicystic dysplastic kidney (MCDK): most common entity (see Fig.15.15).
Said to originate from severe early upper tract obstruction causing severe cystic
dysplasia. Caused by impaired connection between ureteric bud and renal blas-
tema (or vascular insult). Classically dened by multiple large cysts with poten-
tially some echogenic undifferentiated central parenchyma (may even exhibit
residual vascularisation). Continuous transition to severe obstructive uropathy
with dysplastic cysts of parenchyma—thus some residual central collecting sys-
tem or residual ureter may be visible. Commonly tend to shrink/vanish spontane-
ously; however, some may grow, get infected, cause hypertension or undergo
tumourous transformation (particularly those with vascularised residual paren-
chyma). US monitoring, particularly of the other kidney (particularly if not
hypertrophied) recommended.
Note Often associated with ipsilateral genital malformations, similarly to solitary
kidneys, where contralateral kidney may have involuted during embryology secondary to similar phenomena. Cystic renal buds (remnants of MCDKs? After obstructive cystic dysplasia?) may be found in ectopic position with some residual or absent
392
M. Riccabona
function. Thus always carefully assess entire abdomen and genital tract as well as
contralateral kidney, which should develop compensatory hypertrophy.
Acquired Cystic Kidney Disease
Definition
Number of aetiologies occur and exhibit different features: posttraumatic cysts,
postoperative cysts, acquired cystic kidney disease in renal failure and after
transplantation.
Note Simple renal cyst much rarer in childhood than in adults—every cyst detected
in an infant and young child requires detailed assessment + follow-up.
DDx
Calyceal diverticulum, tertiary calix, cystic remnants of abscess/infection/trauma,
urinoma, and cystic tumours (Fig.15.16).
Role of US
Ideal method for initial investigation/follow-up.
Note Number of cysts and appearance of parenchyma do not necessarily correlate
with renal function.
Additional Imaging
Depending on underlying entity—sometimes no additional imaging, sometimes
assessment for VUR (VCUG/ce-VUS), renal function (scintigraphy/MR urography), or ectopic renal remnants (scintigraphy/MR).
Fig. 15.16 Acquired cystic kidney disease and DD. (a) Postinfectious cyst: somewhat irregular
cyst at previous site of an abscess. (b) Huge cystic mass connected with the upper calyx and showing contrast extravasation on dynamic MRU, consistent with a urinoma or a huge calyceal diverticulum. (c) After heminephrectomy a growing liquid formation (
site—consistent with a postoperative urinoma
+…+) observed at resection
1
15 Ultrasound oftheUrogenital Tract inNeonates, Infants, andChildren
393
Rarely—if unclear or suspicious for malignancy: DDx by CEUS, MR (or CT if
MR unavailable).
Recommendations on when to do what exist as consensus statement—see
Chap. 6.
15.3.1.3 Alteration ofUrinary Drainage
Various underlying entities that cause pathologically altered urine ow/drainage.
Often manifests fetally by “urinary tract dilatation” (UTD) or “pelvicalyceal dilatation” (PCD—old term “hydronephrosis”=HN).
Obstructive and reuxive entities need to be differentiated without specic
features.
Consider alternate dysplastic dilated system/ureter without impairment of urinary drainage.
Urinary Tract Dilatation (UTD) or Pelvicalyceal Dilatation/Distention (PCD)
Definition
Old term hydronephrosis (HN)—should be avoided. Term originally used to
describe any dilatation of collecting system.
Today, due to improved resolution of US equipment, normal distension of pelvicalyceal system visualised even fetally—thus pelvicalyceal distention (PCD) or (as
used in the USA) urinary tract dilatation (UTD) does not denitely indicate
pathology.
Standardised grading established, adapted from the Society of Fetal Urology
(SFU) Classication and Hoffman’s paediatric US HN grading system (PCD 0°–
IV°/V°, see Table15.3a; Riccabona M. etal. Pediatr Radiol 2008:38, update 2017).
Denition relies not on millimetre of pelvic width but also visibility and conguration of collecting system and thinning of parenchyma. Grading independent of aetiology. A different UTD classication was proposed by the American societies
(grade P1–P3), trying to combine foetal and postpartal results as well as including
ureter width, hoping to thus enable a risk based management and streamline postnatal imaging (Table15.3b)—however under discussion, sometimes hardly workable
(Nguyen HT etal., Multidisciplinary consensus on the classication of prenatal and
postnatal urinary tract dilation—UTD classication system. J Pediatr Urol 2014).
Additional US signs that may indicate pathology and prompt further work-up
(“extended criteria”): thickening of ureteral/pelvic wall (>1mm, nonspecic—seen
in infection, oedema, obstruction, VUR), renal parenchymal pathology (e.g. cysts,
altered cortico-medullary differentiation, altered echogenicity), renal size alterations, dilatation of ureter, and bladder pathology.
394
Type 0Type IType II Type III Type IV (Type V)
a
Table 15.3 PCD and UTD grading in neonates and infants
(a) PCD grading according to ESPR and ESUR recommendation (Pediatr Radiol 2008:38, update
2017). PCD 0=no collecting system or minimal renal pelvis visible, considered normal. PCD
I=just renal pelvis visible, axial diameter<7mm, usually considered normal. No calices visible.
PCD II=axial renal pelvis diameter 7–10mm; some calices visible, with normal shape and con-
tour. PCD III=marked dilatation of renal calices and pelvis >10mm, attened papilla, rounded
fornices, no parenchymal narrowing. PCD IV=gross dilatation of the entire collecting system with
narrowed parenchyma. PCD V=used sometimes to communicate an extreme PCD IV with only
thin, membrane-like residual parenchymal rim
The classication was developed trying to integrate the Hofmann US grading and the SFU classication (Fernbach etal.) for US grading of (congenital) “hydronephrosis”
Note: As specically adapted to needs in early childhood, this classication differs from the com-
mon adult grading US grading and can be less useful in older children, in acute obstruction without
underlying dilating uropathy, in dysplasia, and as soon as there is scaring or clubbing
(b) UTD grading of the American Societies (adapted from Nguyen HT etal., Multidisciplinary
consensus on the classication of prenatal and postnatal urinary tract dilation—UTD classication
system. J Pediatr Urol 2014). Composed of pre- and postnatal presentation leading to a risk based
management and imaging strategy
M. Riccabona
Pelvi-ureteric Junction Obstruction (PUJO)
Definition
Narrowing/stenosis of Pelvi-ureteric junction causing impairment/obstruction of
urinary drainage. Aetiology usually congenital may be acquired. Commonly associated with signicant prenatal UTD (>II°).
Note Dilatation best assessed after end of the rst postnatal week—as physiologi-
cal renal immaturity prevents lling of collapsed dilated system during rst days of
life. Standardised hydration essential for proper recognition and grading, particularly for follow-up investigations.
b
15 Ultrasound oftheUrogenital Tract inNeonates, Infants, andChildren
Table. 15.3 (continued)
395
US Findings
Dilatation of pelvicalyceal system (PCD grade III°–V°)—lower grades usually
associated with non-obstructive UPJA or lower grade VUR without thinning of
parenchyma and preserved cortico-medullary differentiation. Ureteropelvic junction narrowed/not depictable; proximal ureter very narrow:
• Pelvic ectasia: only pelvis dilated, calices visualised, but normal conguration,
sometimes associated with non-obstructed ureteropelvic junction anom-
aly (UPJA).
• PCD IV° (and V°) usually indicates high-grade PUJO (Fig.15.17).
• Signs for (chronically) decompensated obstruction: (severe) thinning of paren-
chyma, altered parenchymal echogenicity, lack of cortico-medullary differentia-
tion, delayed or missing normalisation under diuretic stress by furosemide
(diuretic urosonography). Potentially dysplastic cysts.
396
M. Riccabona
a
b
cde
f
Fig. 15.17 US in UPJO (including CDS). (a) Typical appearance of high-grade “hydronephrosis”
(grade IV°) with signicantly dilated collecting system, thinned parenchyma, and renal enlargement (+…+) in PUJO. (b) Cyst-like appearance of grossly enlarged collecting system (PCD V) in
PUJO; peripheral rim-like parenchyma hardly visible but enables differentiation against MCDK
(i.e. central parenchyma, no connections between cystic structures). (c) Axial section of mild
PUJO with only little distension of calices and calyceal neck (
2
(
+…+) with persisting cortico-medullary differentiation (PCD grade III°). (d) Axial section: dilatation of extrarenal pelvis (++) but practically no dilatation of the intrarenal system. (e) Same
patient as in (d) CDS reveals an additional renal artery crossing the pelvi-ureteric junction, possibly causing (intermittent) partial obstruction with dilatation of the renal pelvis. (f) Gross dilatation
of collecting system and pelvis in severe, fetally decompensated PUJO.Echogenic, unstructured,
and narrow parenchyma full with multiple cysts of different sizes (“obstructive dysplasia”). (g, h)
Importance of hydration: kidney scanned in non-hydrated (g) and well-hydrated (h) state, the latter
after furosemide-induced diuretic stress. Note signicant change in dilatation of the renal pelvis
1
(
++) and collecting system impressively demonstrating importance of proper patient preparation
for US studies
g
h
1
+…+) and preserved parenchyma
15 Ultrasound oftheUrogenital Tract inNeonates, Infants, andChildren
397
Note Dilatation does not equal obstruction—US cannot diagnose obstruction.
Even severe obstruction may show only minor distension under insufcient hydration/decreased function or with intermittent as well as per acute obstruction (e.g.
urolithiasis). Diagnosis of severe/decompensated obstruction (which needs
treatment to prevent deterioration of renal function/growth potential) relays on
functional imaging.
CDS
Look for accessory/additional renal vessels that may impair ureteropelvic junction
(Fig.15.17):
• In chronic and non-obstructive dilatation RI symmetric.
• In acute obstruction asymmetric elevation of RI in affected kidney.
• Also assess potential rarefaction of peripheral vascularity (sign of chronic
decompensation with already reduced renal function/scarring), best visualised
on aCDS.
Postoperative transient thickening of pelvic wall, pelvis often smaller (as reduced
by surgery) and dilatation of calices often persists for long time—only normalises
over years, potentially focal perfusion impairment/scar (e.g. at site of perioperative drain).
Note For assessing split renal volume, the dilated collecting system has to be sub-
tracted—best using 3DUS (allows segmentation of collecting system that can be
deducted from overall renal volume, thus allowing exact parenchymal volume calculation—see respective chapters too). Can then be compared to non-obstructed
contralateral side (= split/relative renal size).
Additional Investigations
MAG3 scintigraphy: gold standard for assessing renal function/urinary drainage.
IVU: outdated—replaced by MRU, indicated in complex anatomy, particularly
preoperatively
• In some situations—particularly postoperatively—modied focused IVU help-
ful by assessing anatomy/obstruction (only need few well-timed focused images).
Dynamic diuretic MRU: will in future allow for additional functional assessment.
• No indication for CT, even accessory renal artery seen mostly by US/CDS and
early angiographic phase of MRU.
VCUG or ce-VUS: VUR assessment—particularly if indirect signs seen on US.
• Postoperatively some perform uoroscopic assessment of drainage before
removing drain. Potentially replaceable by intracavitary ce-US (= install UCA in
drain and observe drainage to bladder).
398
M. Riccabona
Uretero-Vesical Junction Obstruction (UVJO)/Obstructive Megaureter (POM/MU)
Definition
Aetiology: stenosis at UVJ or regional dysplasia of ureter with lack of peristalsis,
causing impaired urinary drainage. Potentially associated with anatomic changes at
ostium (low insertion, ureterocele, ectopic ureteric insertion, duplex systems, etc.).
US Findings
Dilatation of ureter, more or less thickening of wall and varying impairment of peristalsis (can be documented by video clips/M-mode) (Fig.15.18):
• Hyperperistalsis indicates stenosis.
• Lack of peristalsis hints at decompensation or dysplastic-atonic segment.
• In complications (e.g. infection): echoes in ureter.
Note Dilatation of ureter does not necessarily correlate with dilatation of renal col-
lecting system—associated kink/relative PUJO will increase intrarenal distension
(PCD II°–V°).
a
bc
de f
Fig. 15.18 POM/MU—M-mode. (a) Two cystiform structures depicted behind well-lled blad-
der lateral to uterus (proper TGC adaptation essential—automatic image optimisation programmes
will not always work for this): to differentiate ovarian cysts from (bilateral) megaureter, longitudinal paramedian section is necessary. (b, c) Dilated ureter (+ +) behind well-lled urinary bladder
in axial (b) and longitudinal (c) section; the latter nicely exhibiting short narrow distal/transmural
section (obstructive megaureter). (d) M-mode documents lack of peristalsis in dysplastic widened
ureteral segment (neonate with primary megaureter). (d) Signicantly dilated renal collecting system in child with megaureter. Note cystiform uid-lled structure below the lower pole of kidney
(+ +) representing loop of tortuous megaureter. (e) Pelvi-ureteric junction has kink-like anatomy
explaining intermittent secondary upper obstruction in addition to megaureter
15 Ultrasound oftheUrogenital Tract inNeonates, Infants, andChildren
399
CDS
No specic ndings. Assessment of ureteric inow jet may be helpful but potentially
misleading. Improves depiction of ostium—thus identication of atypical insertion.
Additional Investigations
IVU replaced by (diuretic contrast-enhanced) MRU; for anatomic display T2-MRU.
VCUG/ce-VUS for differentiation of dilating VUR.
MAG3 scintigraphy—used for drainage assessment, split renal size, and function and assessment of ureteral peristalsis (or dynamic MRU).
Posterior Urethral Valve (PUV)
Definition
Most common in baby boys. Has a number of forms. Severe distal obstruction often
associated with upper tract pathology—high probability of congenital renal dysplasia and chronic renal failure.
US Findings
• Thickened bladder wall, trabeculation, (pseudo-)diverticula, enlarged capacity,
typical valve-like conguration of bladder neck (particularly well seen by peri-
neal US during voiding attempts) (Fig.15.19).
• Secondary high-grade VUR or obstruction by thickened bladder wall, associated
with more or less renal dysplasia, dilation of collecting system, potentially pop-
off urinoma (Fig.15.20)—the latter will prevent kidney from further damage.
This can also occur in other scenarios (e.g. obstructing ureterocele) (Fig15.20e).
CDS
Demonstrates renal perfusion; helps assessment of severely dysfunctional kidneys.
ce-VUS may show valve (perineal approach during voiding); VUR may show
pop-off urinoma.
DDx
• Prune belly syndrome (hypoplastic abdominal wall, cryptorchidism, hypoplastic
prostate, hypoplasia of posterior urethra, commonly associated with complex
urinary tract anomalies/dilated ureters with less-dilated intrarenal collecting sys-
tem and dysplastic parenchyma).
• Neurogenic bladder.
• High-grade VUR.
Additional Investigations
• Initial conrmation by VCUG recommended.
• Early urinary drainage either by bladder relief or nephrostomy.
400
M. Riccabona
a
c
e
g
b
d
f
h
i
Fig. 15.19 US in posterior urethral valve (PUV). (a) Longitudinal section of large bladder with
impressive wall thickening and obstruction of ureteral ostium (arrow) in baby with PUV. (b) Cross
section through wall-thickened urinary bladder (after drainage via catheter) shows dilated ureter
behind bladder and trabeculation. (c) Normal perineal US in baby boy (no voiding). (d) Perineal
US, neonate: open bladder neck and proximal urethra to pelvic oor when trying to void—not to
be confused with PUV (as on VCUG). (e) Normal male urethra during voiding on ce-US. (f)
Typical valve conguration of PUV on perineal US during voiding. (g) ce-VUS: valve-like urethra
conguration nicely demonstrated during voiding; catheter only seen in basic image, contrast
agent better visualised in left, dedicated contrast-specic image. (h) Para-ureteric cyst (*) seen on
perineal US with no connection to urethra. (i) Ureteric duplication posing as a diverticulum (*)
with some sort of ureteric stenosis (incomplete valve/ureteric fold) depicted by retrograde
US-urethrography (arrow=catheter for US-urethrography using saline)