antenatal Hydronephrosis and approach

antenatal Hydronephrosis and approach

1. Approach to congenital Hydronephrosis Presesented by-Dr.Santhosh Reddy Moderator – Dr.Arnab Senguptha

2. Overview Definition and etiology Grading of fetal and neonatal hydronephrosis Approach to hydronephrosis Fetal Neonatal

3. Hydronephrosis: Dilation of the renal pelvis with or without dilation of the renal calyces

4. Physiologic Hydronephrosis At least 80% of all prenatally detected mild hydronephrosis (APRPD 7-10 mm at 30 weeks’ gestational age) resolves spontaneously and is not associated with an anatomic abnormality of the urinary tract. Hydronephrosis, which improves or resolves during the pregnancy, is unlikely to have any postnatal implications. Physiologic hydronephrosis may be caused by a delay in the maturation of the ureter, which leads to transient urinary flow obstruction. The hydronephrosis in these patients generally resolves within the first 2 years of life.

5. Ureteropelvic Junction Obstruction - UPJ obstruction is the most common cause of moderate to severe congenital hydronephrosis and may be the result of incomplete recanalization of the proximal ureter, abnormal development of the ureteral musculature, abnormal peristalsis, or polyps. UPJobstruction is more common in boys and may be associated with other congenital anomalies (including other genitourinary malformations) or syndromes. The diagnosis is confirmed by an obstructive pattern observed on a diureticenhanced radionuclide scan, antibiotic prophylaxis to prevent urinary tract infection, which was shown to be effective in preventing infection in patients with high-grade hydronephrosis. Temporary relief of obstruction may be necessary and is often achieved by placement of a percutaneous nephrostomy drain. Definitive treatment often involves surgical repair About 20%-25% of children with UPJ obstruction will have surgery for decreased renal function or progressionof hydronephrosis.

6. Ureterovesical Junction Obstruction- UVJ obstruction is another cause of congenital hydronephrosis and is characterized by hydronephrosis with associated ureteral dilatation. This disorder may be related to the deficient development of the distal ureter or the presence of a ureterocele and is likely to spontaneously resolve in 70% of patients. The diagnosis is confirmed by a radionuclide scan and VCUG. UVJ obstruction is usually not associated with other congenital malformations. A ureteral dilation greater than 1 cm is associated with higher risk of urinary tract infection so antibiotic prophylaxis may be indicated. Temporary or permanent surgical interventions may be required, based on the clinical situation.

7. Vesicoureteral Reflux - VUR accounts for 10%-40% of neonatal hydronephrosis. It is defined as the retrograde propulsion of urine into the upper urinary tract during bladder contraction. The underlying cause of VUR is believed to be ectopic insertion of the ureter into the bladder wall, resulting in a shorter intravesicular ureter, which acts as an incompetent valve during urination. Vesicoureteral reflux is graded from I to V,

8. Eagle-Barrett Syndrome - Eagle-Barrett (“prune belly”) syndrome (EBS) is characterized by a triad of genitourinary abnormalities (markedly enlarged bladder with poor contractility without urethral obstruction, megaureters , and renal dysplasia), deficiency of abdominal wall musculature, and cryptorchidism . The estimated incidence is 1 in 35,000-50,000 live births, with more than 95% of the cases occurring in boys.

9. Posterior urethral valves (PUV) represent the most common cause of lower urinary tract obstruction, with an incidence of 1 in 5000-8000 live male births. A posterior urethral valve is composed of a congenital membrane that obstructs or partially obstructs the posterior urethra and is formed when the mesonephric duct fails to adequately regress. Findings on prenatal ultrasound may include hydronephrosis; dilated ureters; a thickened, trabeculated bladder; dilated proximal urethra; and oligohydramnios . The antenatal presentation may include a palpable, distended bladder, poor urinary stream, and signs and symptoms of renal and pulmonary insufficiency. The VCUG is diagnostic for PUV and reveals associated VUR in 30% of patients

10. Multicystic Dysplastic Kidney - Multicystic dysplastic kidney MCDK represents the most severe form of renal dysplasia and is characterized by a nonfunctioning kidney that is devoid of normal renal architecture and composed of multiple large cysts that resemble a cluster of grapes About 20% of children with unilateral MCDK will have vesicoureteral reflux into the contralateral kidney, which is grades I-III in 96%.

11. Grading Renal pelvic diameter (RPD) Society of Fetal Urology (SFU) criteria Urinary tract dilation (UTD) classification system

12. Renal pelvic diameter (RPD) The most generally accepted method to define and grade fetal hydronephrosis is measurement of the maximum APPD, also referred to as RPD, in the transverse plane . Fetal hydronephrosis is graded according to the RPD during the second and/or third trimester of pregnancy. RPD is a measure of collecting system dilation and does not reflect the extent of hydronephrosis and parenchymal changes, such as increased echogenicity, thinning, or caliectasis . Indian J Nephrol . 2013 Mar-Apr; 23(2): 83–97.Revised guidelines on management of antenatal hydronephrosis A. Sinha ,  A. Bagga ,et al.

13.   Descriptive definition of hydronephrosis by Antero Posterior Diameter. Classification of hydronephrosis Second trimesterAPD in mm Third trimesterAPD in mm Mild 4-6 7-9 Moderate 7-10 9-15 Severe > 10 > 15

14. Society of Fetal Urology (SFU) The SFU developed criteria for the diagnosis and grading of fetal hydronephrosis based upon the degree and site of pelvic dilation, number of calyces seen, and the presence and severity of parenchymal atrophy . The SFU grading system focuses on the degree of hydronephrosis in the kidney without directly assessing the state of the ureter and bladder: Indian J Nephrol . 2013 Mar-Apr; 23(2): 83–97.Revised guidelines on management of antenatal hydronephrosis A. Sinha ,  A. Bagga ,et al.

15. 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

16. Urinary tract dilation (UTD) classification system The UTD classification system is based on six ultrasound findings and is stratified based on GA and whether the detection is antenatal or postnatal Anterior and posterior RPD Calyceal dilation Renal parenchymal thickness Renal parenchymal appearance Bladder abnormalities Ureteral abnormalities Journal of pediatric urology 2014,10,982-999, Multidisciplinary consensus on the classification of prenatal and postnatal urinary tract dilation (UTD classification system) Hiep T. Nguyen et al.

17. UTD A1 : APPD; 16 to 27 weeks: 4 mm to <7 mm ≥ 28 weeks: 7 mm to <10 mm With or without central calyceal dilatation UTD A2-3 : APPD; 16 to 27 weeks: ≥7 mm ≥28 weeks: ≥10 mm Peripheral calyceal dilatation Abnormal parenchyma thickness or appearance Abnormal ureter or bladder Unexplained  oligohydramnios

18. UTD P1 (low risk) : APPD 10 mm to <15 mm Central calyceal dilatation UTD P2 (intermediate risk) : APPD ≥15 mm Peripheral calyceal dilatation Abnormal ureter UTD P3 (high risk) : APPD ≥15 mm Peripheral calyceal dilatation Abnormal parenchymal thickness or appearance Abnormal ureter Abnormal bladder

19. Physical examination The neonatal physical examination can identify abnormalities that are indicative of congenital anomalies of the kidney and urinary tract (CAKUT), which are associated with fetal hydronephrosis . These include the following: Abdominal mass - enlarged kidney due to obstructive uropathy or multicystic dysplastic kidney A palpable bladder in a male infant- posterior urethral valves (PUV). A male infant with deficient abdominal wall musculature and undescended testes- prune-belly syndrome outer ear abnormalities - associated with an increased risk of CAKUT. A single umbilical artery - increased risk of CAKUT, particularly vesicoureteral reflux (VUR). Spinal and/or lower extremity abnormalities suggesting a neurogenic bladder, which may result in hydronephrosis and dilated ureters

20. Imaging studies USG Voiding cystourethrogram Diuretic renography   Magnetic resonance urography

21. Voiding cystourethrogram   VCUG is performed in the majority of neonates with persistent postnatal hydronephrosis (RPD ≥10 mm) to identify patients with bladder outlet obstruction, most commonly PUV,VUR MCU be performed in patients with unilateral or bilateral hydronephrosis with renal pelvic APD > 10 mm, SFU grade 3-4 or ureteric dilatation . MCU be performed early, within 24-72 h of life, in patients with suspected lower urinary tract obstruction . In other cases, the procedure should be done at 4-6 weeks of age. MCU done for infants with antenatally detected hydronephrosis who develop a urinary tract infection 

22.   MCU is also required in patients with history of milder grades of ANH who show worsening hydronephrosis , progressive parenchymal thinning or occurrence of UTI.

23. Diuretic renography     Diuretic renography is used to diagnose urinary tract obstruction in infants with persistent grade 4 and possibly grade 3 hydronephrosis after a VCUG has demonstrated no VUR . It measures the drainage time from the renal pelvis, and assesses the relative contribution of each kidney to overall renal function. The test requires insertion of a bladder catheter to relieve any pressure that can be transmitted to the ureters and kidneys. Intravenous access is needed for hydration and the administration of the radioisotope and diuretic. The preferred radioisotope is technetium-99m-mercaptoacetyltriglycine (Tc99mMAG3), which is taken up by the renal cortex, filtered across the glomerular basement membrane (GBM) to the renal tubules, and excreted into the renal pelvis and urinary tract. Journal of pediatric urology  VOLUME 15, ISSUE 2 , P128-137, APRIL 01, 2019, Diuresis renography in the evaluation and management of pediatric hydronephrosis: C.E. Bayne et al.

24. Infants with moderate to severe unilateral or bilateral hydronephrosis (SFU grade 3-4, APD >10 mm) who do not show VUR should undergo diuretic renography . Infants with hydronephrosis and dilated ureter(s) and no evidence of VUR undergo diuretic renography . Diuretic renography be performed after 6-8 weeks of age. The procedure may be repeated after 3-6 months in infants where ultrasound shows worsening of pelvicalyceal dilatation

25. Cortical retention of tracer due to acute left UPJ obstruction

26. Magnetic resonance urography     Magnetic resonance urography (MRU) in children is becoming more commonly used in the diagnosis and management of congenital uropathies , such as ureteropelvic junction obstruction (UPJO) . MRU is especially useful in the management of obstructed kidneys that have rotation or ascent anomalies, or are single. MRU can more clearly define the anatomy and delineate the proper surgical approach ( ie , retroperitoneal versus transperitoneal ).

27. The disadvantage of MRU is that the study often requires general anesthesia or heavy conscious sedation in children. However, for patients in the newborn period, many centers are now performing "swaddle MRI" after the infant falls asleep after feeding, thus avoiding general anesthesia and conscious sedation. Another disadvantage is the use of the contrast agent gadolinium, which can only be used if the renal function is normal (requiring a preprocedure serum creatinine test) because of reports of irreversible renal fibrosis in patients with renal insufficiency

28. MR urography showing left PUJ obstruction

29. Management of antenatal hydronephrosis

30. Repeat USG at 4-6weeks Normal USG abnormal No further work up required No hydronephrosis(SFU grade 0&APD <7mm

31. SFU grade 1&2 or APD <10 mm and SFU grade 3 &4 or APD >10 and Normal ureter ureter dilated USG monotoring at 4-6 wk , MCU at 4-6 weeks then every 6-12 months till resolution Normal VUR present RDS at 6-8 weeks Antibiotic prophylaxis Unilateral or bilateral hydronephrosis and LUTO unlikely

32. Renal dynamic scan at 6-8 weeks Non obstructive pattern;USG Obstructive pattern with differential moniring till resolution function<40%: consider pyeloplasty Persistence or worsening : antibiotic prophylaxis Repeat RDS

33. MCU within 48 hours LUTO absent LUTO present VUR present Refer to pediatric surgeon Give antibiotic prophylaxis Features of LUTO

34. Emergency Measures to be taken within first 48 h after birth in infants diagnosed with antenatal hydronephrosis. USG Suspected lower tract obstruction,  e.g ., Posterior urethral valves, prune belly syndrome Bilateral hydronephrosis with or without hydroureter Solitary kidney with APD > 15 mm or SFU grade 2 or more Antibiotic prophylaxis Suspected lower tract obstruction APD > 10 mm or SFU grade 2 or more in the third trimester Solitary kidney with hydronephrosis of any grade Bilateral hydronephrosis VCUG Suspected posterior urethral valves antenatally Catheterization Suspected lower tract obstruction-posterior urethral valve or prune belly syndrome

35. NON EMERGENCY POST NATAL MANAGEMENT Since infants are relatively dehydrated at birth, the initial postnatal ultrasonography should be performed after 48 h of birth. Also breast fed neonates may not be adequately hydrated until a steady milk flow is established. Hence the first postnatal ultrasound is preferably done between 3-7 d after birth.

36. The exceptions to this : Suspected lower tract obstruction  e.g ., Posterior urethral valves; Severe bilateral hydronephrosis with or without hydroureter ; and Solitary kidney with hydronephrosis especially if the APD is > 15 mm or it is SFU grade 2 or more in the third trimester.

37. Ultrasonography at 5-7 d would show one of the following scenarios: No hydronephrosis -Normal pelvicalyceal system; Unilateral hydronephrosis; Bilateral hydronephrosis; Unilateral Hydronephrosis with hydroureter ; and Bilateral hydronephrosis with bilateral hydroureter

38. UNILATERAL HYDRONEPHROSIS BUT NO HYDROURETER After the Initial Ultrasound at 5-7 d after birth the next follow up ultrasound should be done at 4 wk. But chemoprophylaxis is indicated in those with moderate or severe degree of hydronephrosis till VCUG is done. The timing of VCUG in this group of patients should be at 4-6 wk.

39. It is recommended that if no reflux is seen then chemoprophylaxis can be stopped unless it is a solitary kidney.  In those with VUR chemoprophylaxis should be continued If there is mild hydronephrosis and for moderate hydronephrosis confirmed at 1 mo a repeat ultrasound is indicated at 3 mo and then six monthly till the age of 3 years and then yearly till the age of six years. Whenever the sonography shows resolution of hydronephrosis a repeat ultrasonography at 3-6 mo is warranted to confirm the finding as recurrence is noted in previously resolved hydronephrosis .

40. For severe grade of hydronephrosis ultrasound at 1 mo confirms the findings and then further sonography is done based on the need for intervention. If conservative management is opted then ultrasonography should be done at monthly intervals for 3 mo , then bimonthly till the age of 1 year. Any sign of increasing hydronephrosis would warrant intervention or a further radionuclide study to determine the need for intervention.

41. Unilateral hydronephrosis with unilateral hydroureter megaureter-retrovesical ureteric diameter > 7 mm from 30 wk gestation onwards is taken as megaureter . Antibiotic prophylaxis-is recommended for the first 6-12 mo of life [ as the risk of UTI is higher with uretero vesical junction obstruction than with PUJ obstruction

42. Bilateral hydronephrosis with bilateral hydroureter Antibiotic prophylaxis-recommended; VCUG-to be done at the earliest under antibiotic cover to confirm or rule out posterior urethral valves; Renogram -to be done using MAG3 or EC within the first 4 wk of life, in cases of bilateral megaureter

43. ANH carries a significant risk of a postnatal pathologic outcome Mild –88.3% Moderate-45.9% Severe-11.9% Continuous prophylaxis cephalexin 10 mg/kg/d HS, Trimethoprim 1-2 mg/kg/d HS, Nitrofurantoin 1-2 mg/kg/d HS Counsel parents regarding increased risk of urinary tract infections due to VUR ,perform urine culture for any fever without focus. Pediatrics office journal of the american academy of pediatrics Antenatal Hydronephrosis as a Predictor of Postnatal Outcome: A Meta-analysis Richard S. Lee et al.  Pediatrics  August 2006, 

44. Indications for surgery obstructive pattern on diuretic renography and differential function exceeding 40%.  infants with lower urinary tract obstruction  obstructed hydronephrosis , and either reduced differential renal function or its worsening on repeat evaluation bilateral hydronephrosis or hydronephrosis in solitary kidney showing worsening dilatation and deterioration of function. Other indications for surgery include presence of pain, palpable renal lump or recurrent febrile UTI.