Bildediagnostikk av urinsystemet hos barn Flashcards
Hvilke kliniske tilstander kan føre til sykdom i nyrene?
Hva gjør du i dette tilfellet?
Blunt abdominal trauma, esp. in a «high energy» trauma setting (3 meter fall, child), should ALWAYS be further investigated.
Think about what internal organs could have been injured! Dont forget about fractures (rib fractures don’t need to be investigated by themselves).
In the ER:
- Blood samples and dipstick (microscopic hematuria)
- Continuous surveillance of vital parameteres
- Imaging (start with ultrasound/FAST US and x-ray thorax & pelvis)
Findings:
- Free fluid (in trauma setting suspicious of blood; hemoperitoneum = anechoic area around the left kidney and above the bladder)
- Suspicious damage to the left kidney
parenchyma - Possible underlying, undiagnosed condition in the left kidney; hydronephrosis with thining of the parenchyma (= long lasting condition) most probably secondary to PUJO / pelvico-ureteric junction obstruction
Hva viser bildene?
Sagittal CT images (w/intravenous contrast i venous phase):
First (left): Healthy right kidney
Second (right): Injured left kidney with hydronephrosis and thining of the parenchyma
Hva viser bildene?
Sagittal CT images (w/intravenous contrast in multiple phases):
First: Injured left kidney with hydronephrosis and thining of the parenchyma
Second: «Standard» 10 min excretory phase CT urography. One would expect more homogenous contrast filling in the collecting cystem. Here you see only contrast i the peripheral calyces. Arrow pointing at the site of rupture of the extrarenal pelvis.
Third: Delayed excretory phase CT urography. Contrast spilling outside of the renal pelvis; urine leak (norwegian: «uroplani»).
Kidney is the third most common organ to be injured in abdominal trauma.
Hva er CAKUT?
Congenital anomalies of the kidney and urinary tract (CAKUT) constitute approximately 20 to 30 percent of all anomalies identified in the prenatal period.
The majority of renal malformations are detected antenatally because of the widespread use and sensitivity of routine fetal ultrasonography.
Hvilke abnormaliteter forekommer ved embryogenesen og organogenesen ved hhv.:
- Nyrene
- Samlesystemet
- Reproduktive organer
It´s important to know something about congenital anomalies:
Very common (after neurological and cardial defects)
Born with / diagnosed in utero and fully diagnosed and followed postnatally
Can lead to kidney failure and hypertension if unrecognised
Hva viser disse bildene?
Refers to an absence of a testis (or testes) in the scrotal sac. It may refer to an undescended testis, ectopic testis, or an atrophic or absent testis. Correct localisation of the testes is essential because surgical management varies on location. Incidence 3% term and 30% preterm boys.
Ultrasound has 45% sensitivity, 78% specificity, and 88% accuracy for localisation of an undescended testis and is more accurate than clinical examination.
Left picture shows a lack of a testis in the scrotal sac; the undescended testis is a homogeneously hypoechoic ovoid structure, similar to the contralateral testis, with an echogenic mediastinum testis the ectopic testis may be high up in the scrotum or within the inguinal canal (39%) ultrasound is limited in intra-abdominal, pelvic or retroperitoneal/ectopic testes (20%) ultrasound is also inconclusive in evaluation of the atrophic testis (41%), where it is difficult to differentiate from lymph nodes or the pars infravaginalis gubernaculi.
Agenesis of a testis is frequently associated with other urological abnormalities on that same side
MRI is the best cross-sectional modality to assess crypto-orchidism (replacing CT). It has a higher sensitivity than ultrasound (~90%) and a higher specificity (100%).
Hvordan behandler man barn med testisretensjon?
Kryptorkisme
Most undescended testes at birth descend in the first three months after birth.
Orchiopexy is the preferred mode of management in case of viable testes high-up in the scrotum or within inguinal canal/abdomen. It is performed after 1 year of age since the testes may descend without intervention.
With cryptorchidism there is a 32x increased risk of developing a testicular germ cell tumour, with an incidence of 1 in 2000 (higher in bilateral cases, and in abdominal cryptorchidism). The effect of surgical correction, decreasing the risk of malignancy is controversial but it does allow for easier examination, and - hopefully - earlier detection.
Hvordan klassifiserer CAKUT skiller mellom anomaliene?
Different ways of approaching the categorization/classification of anomalies in the kidney and urinary tract.
The most common classification system of renal and urinary tract anomalies uses two main categories:
- Non-hydronephrotic renal anomalies: No urinary tract dilatation
- Hydronephrotic renal anomalies: Urinary tract dilatation.
Hva kjennetegner non-hydronephrotic renal anomalier?
Renal agenesis refers to congenital absence of the kidney, which can be bilateral or unilateral.
Unilateral agenesis (1:500)
- Not usually of any major health consequence (avoid contact sports?)
- Compensatory hypertrophy of the remaining kidney
- Almost half (38–48%) of all patients with a congenital solitary functioning kidney (CSFK) have other urological abnormalities such as renal ectopy, vesico-ureteric reflux (VUR), pelvi-ureteric junction (PUJ) or vesicoureteric junction (VUJ) obstruction, ureteric duplication or ectopic insertion of the ureter.
Bilateral agensis (1:8000)
- Potters syndrome (olgiohydramnion, increased pressure and can cause further malformations) – lethal/not compatible with a normal life
Dysplasia (MCDKD)
- Most common type of renal cystic disease
- Kidney consists of varying sizes and has reduced or no function
Hva viser dette bildet?
Most common fusion abnormality of the kidney (1:400 – 1:500).
The normal ascent of the kidneys allows the organs to take their place in the abdomen below the adrenal glands. However with a horseshoe kidney, ascent into the abdomen is restricted by the inferior mesenteric artery (IMA) which hooks over the isthmus. Hence horseshoe kidneys are low lying.
May occur as isolated anomaly or with other anomalies (1/3), such as: Vesico-urethral reflux (VUR), hypospadias, retrocaval ureter, imperforate anus, Meckel diverticulum.
About 1/3 are asymptomatic
When present, symptoms stem from hydronephrosis, stones, infection
Complications
Ureteropelvic junction obstruction
Render the kindeys susceptible to trauma
Recurrent infections (frequent)
Recurrent calculus formation (frequent)
Increased incidence of Wilms tumors, transitional cell carcinoma and renal carcinoids
Hva kjennetegner hydronephrotic renal anomalier?
PUJO accounts about 50% of all CAKUT’s.
Abberant collagen or fibrotic bands in the localisation of the renal pelvis – proksimal ureter junction. Histological more of an internal obstruction, meaning there is an misallignment of muscle fibers and collagen, leading to thickened adventitia and inflammation
Internal stenosis can be due to incomplete canalization of the ureter in 42nd day of gestation. The canalization of the ureter starts in the middle part. The ureteropelvic‐ and vesicoureteral junction are the last ones to canalize.
Picture:
Key hole sign («nøkkelhull tegn»). Suggested that PUV (posterior urethral valves) are the result of a single pathologic condition of an oblique membrane associated with the verumontanum, which was defined as congenital obstructive posterior urethral membrane (COPUM). About 9% of all prenatal detected hydronephrosis in boys. Can lead to a severe obstructive uropathy.
Hva er et duplext samlesystem?
Complete or incomplete duplication of the collecting system (ureteres fuse before entering bladder)
Ectopic ureter drains the upper pole and enters the bladder inferiorly and medially (Weigert Meyer rule). May be stenotic and obstructed.
Most duplicated systems asymptomatic and diagnosed incidentally.
Duplex collecting systems are seen in 0.7% of the healthy adult population and 2-4% of patients investigated for urinary tract symptoms
A duplex kidney usually does not require any treatment per se, however, complications may necessitate intervention:
- vesicoureteric reflux into lower pole moiety (due to its lateral displacement within the bladder)
- marked hydronephrosis of the upper pole moiety (ureterocele) may have a mass effect or become infected
VUR is seen in the upper-pole moiety, one must suspect a laterally displaced incomplete duplication or an ectopic orifice located within the bladder neck or urethra.
Hvordan kategoriserer man prenatal hydronefrose?
Jmf. The society of Fetal Urology
One of the most common cause of an abdominal mass in the neonate. Hydronephrosis is dilatation of the urinary tract collecting system. This may be due to obstructive causes, reflux, prune belly syndrome, or other causes.
Dilatation of the upper urinary tract is often detected by means of prenatal ultrasonography performed at or after 20 weeks’ gestation (~1% of pregnancies).
If anomalies are detected prenatally, follow-up renal and bladder ultrasonography (RBUS) should be performed after the first day of life. Newborns have a physiologic oliguria on the first day of life that can lead to false-negative ultrasonography findings. If the findings are normal at this point, ultrasonography should be repeated at the end of the first week prenataly and around 4-6 weeks later. If the hydronephrosis persists greater than 3 months, then further workup should include a nuclear medicine renal scan to evaluate for obstruction and a VCUG to evaluate for reflux
Severe hydronephrosis most likely calls for a renal scan, and it would be useful to obtain a VCUG (Voiding Cystourethrogram) first. Further imaging depends on the resolution of hydronephrosis or demonstration of clinically significant obstruction of the ureteropelvic junction (UPJ) or the ureterovesical junction (UVJ).
Grade I / within normal limits - Splitting of the renal pelvis
Grade II / mild- Renal pelvis dilatation;one or two calyces seen; preserved parenchyma
Grade III / moderate - Diffuse calyceal dilation; preserved renal parenchyma
Grade IV severe - Diffuse calyceal dilation; parenchyma thinned to less than half the thickness of the contralateral kidney
Summary: Don’t focus to much on the different classification systems.
If postnatal ultrasonography reveals only grade I-II hydronephrosis, mercaptoacetyl triglycine (MAG-3) renal scanning is not usually performed, because UPJ obstruction is unlikely.
If postnatal ultrasonography reveals grade III-IV hydronephrosis, renal scanning should be considered after the first month of life. By this time, the glomerular filtration rate (GFR) will have increased sufficiently for the renal scan to be more accurate. However, patients with a solitary kidney or bilateral hydronephrosis have no normal kidney to compare with the dilated kidney. In these patients, radionuclide renal scanning before the first month of life may be necessary to assess whether relief of an obstructive process is indicated.
Diuretic (Lasix) renal scanning (with MAG-3) is used to measure relative renal function and to assess the degree of obstruction by measuring the length of time the radionuclide takes to wash out of the renal pelvis. A greater emphasis is placed on the relative function of the hydronephrotic kidney than on the washout time. The obstructive washout time, typically defined as longer than 20 minutes, may be an indication for intervention.
Hydronephrosis means that the kidneys are abnormally dilated or overfilled with urine. There are several causes, many of which do not cause any harm to the kidneys, but in some cases hydronephrosis can be associated with poorly functioning kidneys. Hydronephrosiscan affect one (unilateral) or both (bilateral) kidneys, and it resolves on its own in about half of all cases.
There are three major categories of hydronephrosis:
- Vesicoureteral refluxis when urine does not properly flow from the kidneys to the bladder, but instead abnormally backs up in the ureter (the tube connecting the kidneys to the bladder).
- Blockage/obstructionoccurring in four possible places:
- Where the kidney meets the ureter (ureteropelvic junction – UPJ)
- Where the ureter meets the bladder (ureterovesical junction – UVJ)
- Within the urethra (the tube that carries urine from the bladder out of the body, occurring only in males) (posterior urethral valves – PUV) - Incorrect attachment of the ureter to the bladder (ectopic ureter orureterocele)
Idiopathichydronephrosisthat has no obvious cause and usually resolves on its own before or after birth
Hvordan klassifiserers hydronefrose?
Pediatrisk
Historically lack of consesus for the description, classification and grading of prenatal to postnatal urinary tract dilatation. Finally in 2014 there was established an international consesus for the «classification of urinary tract dilatation».
The UTD classification system was created by representatives from eight societies who participate in the diagnosis and management of fetuses and children with urinary tract dilation, including the following: American College of Radiology (ACR), American Institute of Ultrasound in Medicine (AIUM), American Society of Pediatric Nephrology (ASPN), Society for Fetal Urology (SFU), Society for
Maternal-Fetal Medicine (SMFM), Society for Pediatric Urology (SPU), Society for Pediatric Radiology (SPR) and Society of Radiologists in Ultrasound (SRU).
These representatives made recommendations based on combining the current literature on imaging and best practices of antenatal and postnatal urinary tract dilation.
Hva er den mest vanlige årsaken til en abdominal masse hos barn, og hvilken bildemodalitet bør man bruke først?
Most common cause of an abdominal mass in children are urinary tract conditions and of those, the most common is hydronephrosis. Ultrasound is the most effective initial imaging technique in a child with an abdominal mass. It is an excellent medium to differentiate between solid and cystic masses.
To find age-normal size:
age-based tables or;
Length = age (years) x 0.6 cm + 1 mm/week of gestational
age (4 cm at full-term)
Don´t forget to check bladder residual volume and thickness.
Don´t forget to asses the genitals
Interpretation/diagnosis of pictures:
Hydronephrosis grade 3
Most common cause in a young child is ureteropelvic juntion obstruction (incomplete blockage at the point where the ureter dranis the pelvis). When you’re little patient drinks a lot, the increased urin output stretches the renal pelvis causing pain. The obstruction can also cause elevated BP.
Treatment: Pyeloplasty (removing the obstructing segment and reconnecting the ureter to the pelvis with a wide anastomosis).
Hva viser bildet?
Interpretation / diagnosis:
Hydronephrosis grade 3
Most common cause in a young child is ureteropelvic juntion obstruction (incomplete blockage at the point where the ureter dranis the pelvis).
It may present in both paediatric and adult populations although they tend to have differing aetiology:
Congenital (neonatal); abnormal muscle arrangement, urotelial ureteral fold, extrinsic ureter compression or encasment by an crossign vessel.
Adult; preceding trauma, obstructing calculus, previous pyelitis with scarring or extrinsic compression (fibrosis/malignancy)
PUJ obstruction is most commonly unilateral but is reported to be bilateral in ~30% (range 10-49%) of cases.
There is a recognised predilection towards the left side (~67% of cases).
Hvordan vurderer man en UPJ hos et barn?
UPJ is evaluated with a nuclear medicine renal scan which can quantitate the degree of obstruction. If the renal function is severely impaired, the UPJ may be surgically repaired.
Right picture shows a PUJ obstruction:
Tc99m-MAG3 demonstrate progressive and persistent accumulation of radio-tracer in the left kidney.
Renogram activity curve
Abnormal radio-tracer uptake in the left kidney with plateau of the curve suggestive of obstruction.
99mTc MAG3:
Agent of choice due to a high extraction rate, which may be necessary for an obstructed system.
Diuretic (Furosemide) renogram is performed to evaluate between obstructive vs. nonobstructive hydronephrosis.
The non-obstructive hydronephrosis will demonstrate excretion (downward slope on renogram) after administration of diuretic from the collecting system. Whereas mechanical obstructive hydronephrosis will show no downward slope on renogram, with retained tracer in collecting system.
Finding:
Dilatation of the renal calyces (and pelvis – not shown in the image).
After finding mild hydronephrosis and treating the UTI, he/she refers the patient for an MCUG (Micturating Cystourethrogram) examination.
Hva slags bildediagnostikk er brukt her? Hva ser vi?
Miksjonsurethrocystografi (MCUG) er en røntgenundersøkelse der man fremstiller urinblæren og urinrøret under selve vannlatingen.
Pre-void contrast filled bladder demonstrated bilateral vesico-ureteral reflux(VUR) with mildly tortuous and moderately dilated ureters, with contrast reaching blunted dilated calyces (low pressure VUR). After voiding, the collecting systems fill even further, compatible with a component of high pressure VUR.
Findings are keeping with bilateral type 4 vesico-ureteral reflux.Maybe a type 5 right side.
Hva kjennetegner VUR?
Common problem encountered in young children. Defined as the retrograde passage of urine from the urinary bladder into the ureter and in more severe cases into the proximal renal collecting system.
Significant potential sequelae resulting from recurrent urinary tract infections and subsequent renal damage (renal scarring og renal failure/reflux nephropathy).
Present in 0.5 - 1% of asymptomatic children but will be present in 25 - 40% of children with urinary tract infections. The incidence of UTI is 8% in females and 2% in males.
Reflux from the bladder into the upper urinary tract predisposes to pyelonephritis by allowing entry of bacteria to the usually sterile upper tract. As such the diagnosis is first suspected after a urinary tract infection in a young child.
Familial component with an incidence as high as 34% and therefore routine screening should be considered in all siblings.
Etiology should be determined and appropriate prophylactic antibiotic therapy begun. Most mild cases will resolve by 5-6 years of age although more severe cases may require corrective surgery.
Most cases of reflux are a primary abnormality due to incompetence of the ureterovesical junction.
(UVJ) normally acts as a passive valve mechanism because of the oblique course of the intramural portion of the ureter. There is also a more active component with peristalsis of the longitudinal muscles of the ureter. Reflux results from immaturity or developmental abnormality of the ureterovesical junction. The length of the intramural portion of the ureter may be too short or insert at an abnormal position into the bladder. The normal insertion of the ureter is one quarter of the distance from the bladder base to the bladder dome.
Vesicoureteric reflux may be an isolated abnormality or associated with other congenital anomalies including:
- Posterior urerthral valves
- Duplex collecting system
Hvilken bildediagnostikk brukes for å diagnostisere VUR?
Micturating cystourethrogram (MCUG) is the primary diagnostic procedure for detection and grading of vesicoureteral reflux.
The MCUG is performed after the diagnosis of a urinary tract infection. Sedation is usually not necessary and can make the study more difficult by inhibiting the voiding reflex. The exam is performed in the radiology fluoroscopy suite, preferably with the ability to record the exam on videotape, as the reflux can be transitory.
Bladder catheter should be placed under sterile conditions
fluoroscopic technique following the principle of “as low as reasonable” (ALARA) radiation exposure
dilute ionic contrast agent
bladder is filled by gravity at a height of approximately 2-3 feet above the table
Bladder capacity can be estimated by: (Patient age + 2) 30.
A preliminary scout film should always be obtained to document any unusual densities or calcifications so not to confuse these with contrast which will have a similar density. Attention should also be drawn to the renal soft tissue outlines to detect any renal developmental anomalies. The spine should be examined for dysraphism.
Film will allow visualization of a ureterocele which can otherwise be obscured with full distension of the bladder
Hva er forskjellen mellom en MCUG hos en jente og en gutt?
During the act of voiding the urethra should be documented. In the female this can be accomplished with an AP view to include the lower bladder. In the male the penis should be displaced to one side to allow for full visualization of the urethral anatomy.
Finally, careful attention should be made for the presence of reflux during voiding. Reflux may only occur during the higher bladder pressures of active voiding. A film over the kidneys will allow documentation of the presence or absence of reflux and allow for grading of the severity of the reflux.
Hvilke fremtidige bildemodaliteter kan (kanskje) brukes for å diagnostisere VUR?
Ultrasound has been investigated as a replacement for traditional fluoroscopic voiding cystourethrogram, by assessing the distal ureters during bladder filling, using micro-bubbles.
Reflux can also be graded, although less precisely, with nuclear cystography. There is no universally accepted grading system for nuclear cystography, with most radiologists simply using the terms mild, moderate, and severe
.
Advantage of nuclear cystography is the lower radiation dosage, which makes it an excellent tool for screening female patients and for following up patients of both sexes.
Disadvantages of nuclear cystography are difficulty in recognising important associated bladder disease (e.g. bladder diverticula), difficulty in visualising the male urethra, and lack of spatial resolution.
MR voiding cystourethrogram protocols are still being developed but have the advantage of not having ionising radiation and of simultaneously imaging the renal parenchyma
