Dilatation of renal pelvis with or without dilatation of ureters.4 grades of fetal hydronephrosis.Assosiated with down's syndrome.

1. FETAL HYDRONEPHROSIS

2. • Fetal Hydronephrosis is dilation of the renal pelvis with or without dilation of the
renal calyces.
• Renal pelvic dilation is a transient physiologic state, however, congenital anomalies
of the kidney and urinary tract (CAKUT) can present with fetal hydronephrosis due
to urinary tract obstruction and vesicoureteral reflux (VUR)
• Majority of cases of fetal hydronephrosis are not clinically significant.
• Incidence of fetal hydronephrosis ranges from 0.6 to 4.5 percent. Occurs
approximately twice as often in males as in females

3. GRADING
• Renal pelvic diameter (RPD)
• The most generally accepted method to define and grade fetal hydronephrosis is
measurement of the maximum anteroposterior diameter of the renal pelvis (APPD)
in the transverse plane
• Mild renal pelvic dilation, also referred to as pyelectasia, is defined as an RPD of ≥4
to 10 mm in the second trimester
• RPD >10 mm in the second trimester is associated with an increased risk of
significant congenital anomalies of the kidney and urinary tract

4. • Society of Fetal Urology (SFU) — The SFU developed criteria for the diagnosis and
grading of fetal hydronephrosis based upon the degree of pelvic dilation, number
calyces seen, and the presence and severity of parenchymal atrophy
●Grade 0 − Normal examination with no dilation of the renal pelvis
●Grade I − Mild dilation of the renal pelvis only
●Grade II − Moderate dilation of the renal pelvis including a few calyces
●Grade III − Dilation of the renal pelvis with visualization of all the calyces, which are
uniformly dilated, and normal renal parenchyma
●Grade IV − Similar appearance of the renal pelvis and calyces as grade III, plus
thinning of the renal parenchyma

5. • Urinary tract dilation (UTD) classification system
• Based on six ultrasound findings—
Anterior and posterior RPD
Calyceal dilation
Renal parenchymal thickness
Renal parenchymal appearance
Bladder abnormalities
Ureteral abnormalities

6. ETIOLOGY
• Transient hydronephrosis
• Congenital anomalies of the kidney and urinary tract (CAKUT)
• Megaureter
• ●Multicystic dysplastic kidney (MCDK)
• ●Ureterocele ●Posterior urethral valves (PUV)
• ●Ectopic ureter
• ●Prune-belly syndrome
• ●Urachal cyst
• ●Duplex collecting system
• ●Urethral atresia

7. • Assosiation with Down syndrome
• Mild hydronephrosis is a common finding in fetuses with Down syndrome.
• Studies that defined hydronephrosis as RPD ≥4 mm in the second trimester
demonstrated hydronephrosis is greater in Down syndrome compared with
normal control fetuses
• The finding of mild hydronephrosis should prompt a detailed assessment of
fetal anatomy to identify other congenital anomalies.
• When pyelectasis is identified in an otherwise normal second trimester fetus
and no previous maternal plasma or serum screening tests for trisomy 21
have been performed, the mother can be offered a cell-free DNA test to
screen for trisomy 21

8. • The timing of prenatal ultrasonography is important for optimal detection of
CAKUT.
• Ultrasonography performed before the 18th to 24th week of gestation can fail to
detect significant disease

10. MANAGEMENT
• Decisions are dependent on the
• presence and nature of associated renal and extrarenal anomalies
• severity of hydronephrosis
• unilateral versus bilateral involvement
• gestational age (GA)
• amniotic fluid volume

11. • Fetuses with bilateral hydronephrosis >4 mm and normal amniotic fluid volume
have serial ultrasound examinations every two to three weeks after diagnosis to
evaluate for progression of dilation and amniotic fluid volume.
• Amniotic fluid is predominantly composed of fetal urine, measurement of
biochemical markers (ie, sodium and beta-2-microglobulin) contained in fetal urine
can be used to assess fetal renal function.

12. • Fetal surgery-
• There have been several prospective and retrospective studies of antenatal surgery in
fetuses with sonographic findings consistent with lower urinary tract obstruction, there is
good evidence that fetal intervention improves renal outcome or long-term patient
• These procedures increase the amount of amniotic fluid, thus potentially improving lung
development and survival rate.
• However, there remains a high rate of fetal demise and chronic renal disease in the
survivors, necessitating renal replacement therapy (RRT) in almost two-thirds of cases.
• In rare cases of post-bladder obstruction (primarily due to posterior urethral valves [PUV]),
we would suggest contacting a tertiary referral center with experience with in utero
intervention.
• In very rare cases with severe bilateral hydronephrosis due to post-bladder obstruction
PUV, we will consider serial fetal bladder taps for amniotic fluid analysis, and if the
appears favorable, perform a vesicoamniotic shunt.

13. PUJ OBSTRUCTION

14. • Ureteropelvic junction (UPJ) obstruction is a partial or intermittent total
blockage of the flow of urine that occurs where the ureter enters the kidney
• The etiology of UPJ obstruction includes both congenital and acquired
conditions.
• UPJ obstruction is the most common pathologic cause of antenatally
detected hydronephrosis

15. • incidence of UPJ obstruction is 1 in 500 live births screened by routine
antenatal ultrasound
• Congenital UPJ obstruction is usually caused by intrinsic stenosis of the
proximal ureter at that UPJ, and less commonly by extrinsic compression
(accessory renal artery) of the UPJ.

16. • Intrinsic narrowing — In most cases of UPJ obstruction, the upper segment
of the ureter is narrowed at the UPJ or kinked as the ureter enters the
resulting in obstruction of urinary flow.
• it is thought that there is an embryologic disruption of the proximal ureter
that alters circular musculature development and/or collagen fibers, and
composition between and around the muscular cells
• Other causes of intrinsic UPJ obstruction, albeit rare, include valvular
folds, persistent fetal ureteral convolutions, and ureteral polyps

17. • Extrinsic compression —
• In approximately 10 percent of pediatric UPJ obstruction, an aberrant or
accessory renal artery or arterial branch may cross the lower pole of the
kidney, resulting in compression of the UPJ and blockage of urinary flow.
• It is possible to identify crossing vessels that cause extrinsic obstruction on
computed tomography (CT) scan or magnetic resonance imaging (MRI),
which are typically obtained for abdominal pain evaluation or other
unrelated pathologies.

18. DAIGNOSIS
• Ultrasonography
• Voiding cystourethrogram
• Diuretic renography
• CT Scan
• MRI

19. DIFFERENTIAL DIAGNOSIS
• Vesicoureteral reflux (VUR)
• Transient hydronephrosis
• Functional hydronephrosis
• Other urological anomalies including posterior urethral valves, congenital
megaureter, ureterocele, and multicystic dysplastic kidney (MCDK)

20. EVALUATION
• Postnatal ultrasound
• Evaluation begins with a postnatal ultrasound to confirm the presence of
persistent hydronephrosis.
• The timing of performing imaging studies evaluation is dependent upon
whether there is bilateral involvement and the severity of antenatal
hydronephrosis Infants with bilateral involvement or with a severe
hydronephrotic solitary kidney require evaluation in the first few days of life
because of the increased likelihood of significant disease and need for early
intervention.

21. • In general, however, examination should be avoided in the first two days
after birth, because hydronephrosis may not be detected because of
extracellular fluid shifts that will underestimate the degree of hydronephrosis.
• Therefore, in unilateral disease regardless of severity, ultrasonography should
be performed at least after 48 hours of life. We use the Society of Fetal
Urology (SFU) system to grade the severity of hydronephrosis from grade 0
(no hydronephrosis) to grade IV (severe hydronephrosis)

22. • Voiding cystourethrogram (VCUG)-
If the VCUG is negative (no reflux or PUV) and the infant has persistent
postnatal severe hydronephrosis (renal pelvic diameter [RPD] ≥15 mm), a
diuretic renography is performed to detect possible obstruction
If the VCUG is negative (no reflux or PUV) and the infant has persistent
postnatal hydronephrosis that is not severe (RPD <15 mm), a follow-up
ultrasound is performed at three months of age to monitor the degree of
hydronephrosis.
If dilatation progresses to the threshold of RPD ≥15 mm, a diuretic renography
should be obtained at that time to determine the relative function of the
affected kidney.

23. MANAGEMENT
• In symptomatic patients, pyeloplasty is performed and consists of resecting
the atretic or stenotic segment, and reattaching the normal ureter to the
renal pelvis, thereby relieving the obstruction.
• If the obstruction is due to an aberrant renal blood vessel, the UPJ is
repositioned anatomically above the blood vessel preventing further
obstruction

24. • Asymptomatic patients —
• The ultimate goal of management is to preserve renal function and avoid
unnecessary surgery.
• Managing asymptomatic patients is challenging, because the natural course
of UPJ obstruction is variable.
• It appears that many patients will have stable renal function and
improvement in the degree of hydronephrosis during long periods of
observation.
• However, others will have deterioration of their renal function, and appear
benefit from surgical correction. As a result, there is no reliable method to
predict whether the function of a kidney with UPJ obstruction will remain
unaffected or deteriorate with time.

25. ANTIBIOTIC PROPHYLAXIS
• Antibiotic prophylaxis has been recommended because urinary stasis is
believed to be a risk factor for urinary tract infection (UTI), it does not appear
that it is beneficial in children with UPJ obstruction.

26. • Surgical options -
• Open dismembered pyeloplasty
• Laparoscopic and robotic pyeloplasty
• Alternative surgical techniques, such as percutaneous and retrograde
endopyelotomy, have been used in adults

27. Surgical intervention is performed for the following indications:
• Symptoms including pain, infection, and renal stones.
• Increasing grade of hydronephrosis, and decrease in function of the affected
kidney so that it is less than the threshold of 40 percent of split renal
function, or there is a serial loss greater than 10 percent.
• Parental and/or patient preference to avoid continued invasive testing, and
allow definitive correction of the problem.
• Massive hydronephrosis with an RPD >50 mm.