Antenatal Hydronephrosis

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  • The AFI is the score obtained by adding centimeters of depth of four pockets of fluid.
  • How to explain the table
  • Antenatal Hydronephrosis

    1. 1. Antenataly detected hydronephrosis
    2. 2. Introduction <ul><li>One of the most common abnormalities detected on prenatal ultrasonography </li></ul><ul><li>Routine prenatal USG: </li></ul><ul><ul><li>Detects urinary tract obstruction / reflux prior to the development of complications </li></ul></ul>
    3. 3. Fetal Renal Sonography <ul><li>Fetal kidney visualized (USG) 12-13th wk </li></ul><ul><li>12-40 weeks </li></ul><ul><ul><li>Length increases from 1.0 to 2.7 cm* </li></ul></ul><ul><ul><li>APD from 0.8 to 2.6 cm </li></ul></ul><ul><ul><li>Transverse diameter from 0.9 to 2.6 cm. </li></ul></ul><ul><li>AJR Am J Roentgenol 1991;157:545 . </li></ul>
    4. 5. Renal Physiology <ul><li>Urine formation- first seen at the 5-8th week. </li></ul><ul><li>Urine output </li></ul><ul><ul><li>5 cc/h at the 20th week </li></ul></ul><ul><ul><li>50 cc/h by the 40th week. </li></ul></ul><ul><li>Bladder : visualized by 10-14th week </li></ul><ul><li>Bladder capacity </li></ul><ul><ul><li>10 cc at the 30th week to 50 cc at term </li></ul></ul><ul><ul><li>Br J Obstet Gynaecol 1977;84:205 . </li></ul></ul>
    5. 6. Renal Physiology <ul><li>Urine formation- first seen at the 5-8th week. </li></ul><ul><li>Urine output </li></ul><ul><ul><li>5 cc/h at the 20th week </li></ul></ul><ul><ul><li>50 cc/h by the 40th week. </li></ul></ul><ul><li>Bladder : visualized by 10-14th week </li></ul><ul><li>Bladder capacity </li></ul><ul><ul><li>10 cc at the 30th week to 50 cc at term </li></ul></ul><ul><ul><li>Br J Obstet Gynaecol 1977;84:205. </li></ul></ul>
    6. 7. Amniotic fluid and indices <ul><li>Volume dependent on urine production since 16 th wk </li></ul><ul><li>Amount of fluid (USG) </li></ul><ul><ul><li>amniotic fluid index (AFI). </li></ul></ul><ul><li>Polyhydramnios </li></ul><ul><ul><li>amniotic fluid volume > 1500 cc or AFI > 20-24 </li></ul></ul><ul><li>Oligohydramnios </li></ul><ul><ul><li>amniotic fluid volume < 500 cc or AFI < 5-6. </li></ul></ul>
    7. 8. Defining ANH <ul><li>Anteroposterior diameter (APD) of the renal pelvis in the transverse plane </li></ul><ul><ul><li>most studied parameter for assessing ANH in utero. </li></ul></ul><ul><li>Threshold APD value which separates normal from abnormal does not exist. </li></ul><ul><li>No consensus on the optimal APD threshold for need of postnatal follow up. </li></ul>
    8. 9. <ul><li>APN Guidelines 2001 </li></ul>e = APPD
    9. 10. AP Diameter <ul><li>Factors affecting APD </li></ul><ul><ul><li>gestational age </li></ul></ul><ul><ul><li>hydration status of the mother </li></ul></ul><ul><ul><li>degree of bladder distension. </li></ul></ul><ul><li>Lower cut offs </li></ul><ul><ul><li>more sensitive in detecting postnatal pathology </li></ul></ul><ul><ul><li>but has higher false positive rates. </li></ul></ul>
    10. 12. 90 th 10 th 50 th 2 nd 3 rd
    11. 13. <ul><li>APD>4-5 mm Threshold for abnormal . </li></ul><ul><li>APD>15mm Severe hydronephrosis </li></ul><ul><li>Journal of Paediatric Urology (2010) 6, 212-231 </li></ul>
    12. 14. Disadvantages and limitations: APD <ul><li>May not accurately reflect the degree of hydronephrosis </li></ul><ul><li>Does not consider calyceal dilation / parenchymal changes </li></ul><ul><ul><li>may reflect more severe obstruction. </li></ul></ul>
    13. 15. Epidemiology <ul><li>1-5 % of all pregnancy </li></ul><ul><li>Male :female = 2:1 </li></ul><ul><li>Bilateral 20-40% </li></ul>
    14. 16. <ul><li>Indian studies: 0.2 % among live born babies </li></ul>
    15. 17. Etiology: Antenatal Hydronephrosis
    16. 18. Transient hydronephrosis <ul><li>Incidence: ranges from 41 to 88% </li></ul><ul><li>Etiology : </li></ul><ul><ul><li>may be a narrowing of the ureteropelvic junction (UPJ) </li></ul></ul><ul><ul><li>natural kinks and folds that occur early in development that resolve as the patient matures. </li></ul></ul><ul><li>Transient hydronephrosis versus clinically significant UPJ obstruction: controversial challenges in modern pediatric urology. </li></ul><ul><li>Most children with a APPD <6 mm diagnosed during the 2nd trimester or < 8 mm diagnosed during the 3rd trimester have transient hydronephrosis. </li></ul>
    17. 19. Transient hydronephrosis
    18. 20. Posterior Urethral Valves Sonography Dilated ureter and renal pelvis and dilated bladder with a dilated posterior urethra
    19. 21. Posterior Urethral Valves Sonography
    20. 22. UPJ obstruction
    21. 23. Multicystic dysplastic kidney
    22. 24. Grading of ANH <ul><li>Using APD thresholds </li></ul><ul><ul><li>ANH classified in the 2nd & 3rd trimester </li></ul></ul><ul><ul><li>Provides prognostic information. </li></ul></ul>
    23. 25. Estimate of distribution by severity <ul><li>J obstet gynecol 2005 ;25:119 </li></ul>
    24. 26. Grading of Hydronephrosis <ul><li>Society for Fetal Urology (SFU) </li></ul><ul><ul><li>proposed a 5-point numerical grading system </li></ul></ul><ul><ul><li>Based on the postnatal appearance of the renal pelvis, calyces, and renal parenchyma. </li></ul></ul><ul><li>Pediatr Radiol (1993) 23:478-480 </li></ul>
    25. 27. <ul><li>Pediatr Radiol (1993) 23:478-480 </li></ul>
    26. 28. Other sonographic parameters <ul><li>Poor corticomedullary differentiation </li></ul><ul><li>(lack of US visualization of the renal pyramids) </li></ul><ul><li>Increased echogenicity </li></ul><ul><li>Presence of renal cysts </li></ul><ul><li>Perinephric urinoma </li></ul>
    27. 29. Post Natal Pathology likely <ul><li>Oligohydramnios </li></ul><ul><li>Parenchymal thinning </li></ul><ul><li>Calyceal dilatation </li></ul><ul><li>Ureteral dilatation </li></ul><ul><li>Chromosomal anomalies or multiple system malformations. </li></ul>
    28. 30. <ul><li>Severe bladder outlet obstruction </li></ul><ul><ul><li>Oligohydramnios, dilated posterior urethra (keyhole sign), ANH, thick-walled bladder, and increased renal echogenicity </li></ul></ul><ul><li>Therapy </li></ul><ul><ul><li>Counselling & </li></ul></ul><ul><ul><li>Possible fetal intervention such as </li></ul></ul><ul><ul><ul><li>early delivery or </li></ul></ul></ul><ul><ul><ul><li>vesicoamniotic shunting </li></ul></ul></ul>
    29. 31. Predictive value of APD-defined ANH for pathology <ul><li>The risk of postnatal pathology per degree of antenatal hydronephrosis </li></ul><ul><ul><li>11.9% for mild </li></ul></ul><ul><ul><li>45.1% for moderate </li></ul></ul><ul><ul><li>88.3% for severe </li></ul></ul><ul><li>Risk of vesicoureteral reflux was similar for all degrees of antenatal hydronephrosis. </li></ul><ul><li>Pediatrics 2006;118:586 </li></ul>
    30. 32. <ul><li>Pediatrics 2006;118:586 . </li></ul>
    31. 33. Natural history of ANH <ul><li>M ajority diagnosed during the second trimester </li></ul><ul><ul><li>resolve during follow-up in the third trimester. </li></ul></ul><ul><ul><li>not associated with clinically significant postnatal pathology. </li></ul></ul><ul><li>Hydronephrosis which is stable/persistent or worsened during pregnancy </li></ul><ul><ul><li>More variable course </li></ul></ul>
    32. 34. Timing of diagnosis and prognostic value <ul><li>First trimester :- poor outcome. </li></ul><ul><li>Second trimester :- overall favourable prognosis. </li></ul><ul><ul><li>Resolve or improve in the majority (approximately 80%) . </li></ul></ul><ul><ul><li>Prognosis better: milder hydronephrosis. </li></ul></ul><ul><li>3rd trimester : higher rates of postnatally confirmed pathology that may require operative intervention </li></ul><ul><li> Ultrasound Obstet Gynecol 2005;25:483. </li></ul><ul><li> Ultrasound Obstet Gynecol 2001;17:191. </li></ul>
    33. 35. Natural History of ANH <ul><li>30-40% of ANH persists postnatally </li></ul><ul><ul><li>Of these 30-40% resolve spontaneously . </li></ul></ul><ul><li>The timing of resolution </li></ul><ul><ul><li>Variable </li></ul></ul><ul><ul><li>Occurring during the first few years of life. </li></ul></ul><ul><ul><li>Earlier with milder grades of hydronephrosis </li></ul></ul><ul><li>Majority of SFU Gd 1-2 resolve by 18 mths </li></ul><ul><li>If increasing hydronephrosis occurs </li></ul><ul><ul><li>it does so early in life, </li></ul></ul><ul><ul><li>often during the first year. </li></ul></ul>
    34. 36. Recommendation for prenatal evaluation of ANH <ul><ul><ul><li>Journal of Pediatric Urology (2010) 6, 212-231 </li></ul></ul></ul>
    35. 37. Suspected Bladder Outflow Obstruction <ul><li>Suspected PUV (oligohydramnios, dilated bladder, bilateral hydroureteronephrosis, male gender) </li></ul><ul><ul><li>Warrants monitoring throughout pregnancy. </li></ul></ul><ul><ul><li>Level 3 US to exclude other organ system abnormalities. </li></ul></ul><ul><ul><li>Fetal imaging every 4 weeks depending on the severity of oligohydramnios </li></ul></ul><ul><ul><li>In increasing oligohydramnios, fetal intervention such as vesicoamniotic shunting may be offered </li></ul></ul><ul><ul><li>Ideal time period to intervention for suspected bladder outlet obstruction is mid-second trimester. </li></ul></ul><ul><ul><ul><li>Allows return of amniotic fluid & promotes lung development. </li></ul></ul></ul>
    36. 38. Predictor of renal function in fetus <ul><li>By analysis of fetal urine biochemistries and electrolytes </li></ul><ul><li>If favorable urine electrolytes -> intervention may be offered as option. </li></ul>
    37. 40. Prenatal Interventions
    38. 41. Imaging modality used in ANH <ul><li>Ultrasonography: </li></ul><ul><li>Most commonly used </li></ul><ul><li>Advantage </li></ul><ul><ul><li>No radiation; Low cost </li></ul></ul><ul><ul><li>Excellent for follow up in pre and post natal life </li></ul></ul><ul><ul><li>Provide anatomical detail. </li></ul></ul><ul><li>Disadvantage </li></ul><ul><ul><li>Poor independent predictor for those who need surgical intervention </li></ul></ul>
    39. 42. Doppler Ultrasonography <ul><li>Based on the fact that obstruction causes an increase in intrarenal arterial resistance resulting in a relative reduction in diastolic flow compared to systolic flow. </li></ul><ul><li>Use for the evaluation of renal obstructive disorders </li></ul><ul><ul><li>currently controversial and not widely utilized. </li></ul></ul>
    40. 43. Postnatal radiological evaluation <ul><li>Depends in part on the degree of hydronephrosis seen during fetal evaluation. </li></ul><ul><li>No study is considered a gold standard for the evaluation of renal obstructive disorders </li></ul><ul><li>Initial postnatal evaluation includes US, DRS and, more recently MRI </li></ul>
    41. 44. Principle of Management <ul><li>Follow hydronephrotic kidneys with serial radiological exams and </li></ul><ul><li>use decreasing differential renal function or </li></ul><ul><li>worsening hydronephrosis </li></ul>Indicators for surgery
    42. 45. Modalities used for Postnatal evaluation <ul><li>Journal of Pediatric Urology (2010) 6, 212-231 </li></ul>
    43. 46. Dynamic renal Scintigraphy <ul><li>adjunct test </li></ul><ul><li>estimate differential renal function and the severity of obstruction. </li></ul><ul><li>Performed after 6 weeks . </li></ul><ul><li>Useful for serial follow up and postoperative assessment of patients with UPJ obstruction and megaureter. </li></ul>
    44. 47. DYNAMIC RENAL SCINTIGRAPHY <ul><li>Tc-MAG3 </li></ul><ul><li>90% bound to plasma proteins </li></ul><ul><li>Principally cleared by tubular secretion. </li></ul><ul><li>Demonstrates parenchymal and collecting system definition. </li></ul><ul><li>Also provides functional quantification </li></ul><ul><li>Lower radiation dose </li></ul><ul><li>Preferred over DTPA </li></ul><ul><li>Tc- DTPA </li></ul><ul><li>Little plasma protein binding </li></ul><ul><li>Cleared exclusively by glomerular filtration. </li></ul><ul><li>Provides excellent visualization of the pelvicalyceal system, ureter and bladder </li></ul><ul><li>Not good for visualization of parenchymal abnormalities. </li></ul><ul><li>Results suboptimal in infants with immature kidneys and a low GFR or in patients with compromised renal function. </li></ul>
    45. 48. Who requires postnatal evaluation? <ul><li>Degree of hydronephrosis useful in decision </li></ul><ul><ul><li>diagnostic imaging </li></ul></ul><ul><ul><li>treatment. </li></ul></ul><ul><li>SFU grades I and II </li></ul><ul><ul><li>resolve with time and </li></ul></ul><ul><ul><li>usually only require US surveillance. </li></ul></ul>
    46. 49. Who requires postnatal evaluation? <ul><li>In moderate hydronephrosis (SFU grade III), DRS may be helpful in determining the timing and role of further studies </li></ul><ul><ul><li>a normal DRS followed by US, </li></ul></ul><ul><ul><li>while an indeterminate DRS may require additional DRS or MRU. </li></ul></ul><ul><li>the criteria for surgical intervention </li></ul><ul><ul><li>variable </li></ul></ul><ul><ul><li>confounded by the surgeon’s and parents’ wishes. </li></ul></ul>
    47. 50. Who requires postnatal evaluation? <ul><li>Severe hydronephrosis (SFU IV), a functional evaluation is recommended </li></ul><ul><ul><li>More likely to have significant urologic pathology </li></ul></ul><ul><ul><li>require surgical intervention. </li></ul></ul><ul><li>SFU IV hydronephrosis should prompt either DRS or MRU. </li></ul><ul><li>For solitary kidneys or bilateral renal involvement, MRU is superior as individual kidney function (GFR) may be assessed. </li></ul>
    48. 51. The timing of postnatal evaluation <ul><li>Unilateral ANH with a normal contralateral kidney : evaluation within the first week of life with a renal US </li></ul><ul><li>In an increased risk of UTI (e.g. girls, uncircumcised boys, moderate to severe antenatal hydronephrosis, familial VUR, etc.) </li></ul><ul><ul><li>Prophylactic antibiotics until the evaluation </li></ul></ul><ul><ul><li>Management discuss with the family </li></ul></ul>
    49. 52. The timing of postnatal evaluation <ul><li>Bilateral hydronephrosis and hydronephrosis in solitary kidneys or in patients with suspected bladder outlet obstruction </li></ul><ul><ul><li>early postnatal imaging is suggested. </li></ul></ul>
    50. 53. <ul><li>Indian Pediatrics 2001; 38: 1244-1251   </li></ul>. Early evaluation is necessary in neonates with solitary kidney, bilateral hydronephrosis or suspected bladder outlet obstruction.
    51. 56. Suggested Algorithm Curr Opn Ped 2009;207-13
    52. 57. Role of VCUG <ul><li>Performed in conjunction with renal studies to rule out VUR </li></ul><ul><li>Most patients with VUR and low-grade hydronephrosis can be followed without surgical intervention. </li></ul>
    53. 58. VUR as a cause of ANH <ul><li>No clear evidence to support or to avoid postnatal imaging for VUR. </li></ul><ul><li>Incidence of VUR </li></ul><ul><ul><li>Up to 30% in children with ANH, including those with resolved hydronephrosis. </li></ul></ul><ul><li>Remains unproven whether the identification and treatment of children with VUR confers any clinical benefit. </li></ul>
    54. 59. Follow-up evaluation <ul><li>A single normal US within the first week of life not adequate to verify absence of obstruction. </li></ul><ul><li>A second US is recommended at 1 month of age as initial follow-up testing. </li></ul>
    55. 60. Late Worsening/ Recurrence <ul><li>1-5%, with all grades of initial hydronephrosis . </li></ul><ul><li>The severity of hydronephrosis is quite significant, being of grade III-IV </li></ul><ul><li>Majority are symptomatic . </li></ul><ul><li>Timing ranges from a few months to 5-6 years . </li></ul>
    56. 61. Follow Up <ul><li>Long term follow up recommended </li></ul><ul><li>Length of surveillance yet to be determined. </li></ul><ul><li>Discharge children with mild or grade I-III hydronephrosis on the 1-month US from further surveillance </li></ul><ul><li>Others recommend serial US and UTI surveillance every 6 or 12 months or in 2-3 years. </li></ul>
    57. 62. Role of antibiotic Prophylaxis <ul><li>Infants with antenatal hydronephrosis are nearly 12 times more likely to have pyelonephritis-related hospitalizations in the first year of life. </li></ul><ul><li>Association is stronger in girls. </li></ul><ul><li>Urology 2007 ;69:970-4 . </li></ul><ul><li>Risk of UTI increases with grade of hydronephrosis . Pediatr Nephrol 2007;22:1727-34 </li></ul><ul><li>J Urol 2008;179:1524 </li></ul>
    58. 63. Antibiotic Prophylaxis <ul><li>No statistical difference in the incidence of UTI in children with ANH on or off prophylactic antibiotics. </li></ul><ul><li>Pediatr Nephrol 2004;19:819. </li></ul><ul><li>Children with prenatal hydronephrosis with persistent grade II hydronephrosis secondary to VUR, use of prophylactic antibiotics significantly reduces the risk of febrile UTIs. </li></ul><ul><li>J Urol 2008;181:801. </li></ul>
    59. 64. Antibiotic Prophylaxis <ul><li>Prophylactic antibiotic in an effort to prevent infant UTIs in high-risk populations </li></ul><ul><ul><li>higher grades of hydronephrosis, </li></ul></ul><ul><ul><li>hydroureteronephrosis , </li></ul></ul><ul><ul><li>VUR, </li></ul></ul><ul><ul><li>or obstructive drainage patterns. </li></ul></ul>
    60. 65. Surgical Intervention <ul><li>Recommendation for surgical intervention </li></ul><ul><ul><li>obstructive wash-out curve ( T½ exceeds 20 min) & significant discrepancy in split renal function (<40%). </li></ul></ul><ul><li>Exception to split renal function- severe bilateral hydronephrosis or obstruction. </li></ul><ul><ul><li>As the absence of a normal contralateral kidney with which to compare the hydronephrotic kidney. </li></ul></ul><ul><li>Renal unit that demonstrates the least function should be repaired first . </li></ul>
    61. 66. Indication for chromosomal evaluation . <ul><li>ANH common in fetuses with serious chromosomal anomalies </li></ul><ul><li>Do not recommend routine karyotyping for all cases of isolated hydronephrosis. </li></ul><ul><li>Consider in the presence of multiple system anomalies. </li></ul>

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