HYDRONEPHROSIS

HYDRONEPHROSIS Caused by obstruction of the urinary tract Typically asymptomatic in its early phases Obstructed kidney secondary to a ureteropelvic junction (UPJ) or ureterovesical junction obstruction Present as a mass or cause upper abdominal or flank pain on the affected side Diagnosed prenatally by ultrasonography *Nelson’s

HYDRONEPHROSIS Degree of hydronephrosis that develops depends on the duration, degree, and site of the obstruction The higher the obstruction, the greater the effect on the kidneys earliest changes in the development of hydronephrosis are seen in the calyces Nausea, vomiting, loss of weight and strength, and pallor are due to uremia secondary to bilateral hydronephrosis *Smith

Etiology Obstruction to urine flow Intrinsic or extrinsic mechanical blockade, functional defects not associated with fixed occlusion of the urinary drainage system Mechanical obstruction At any level of the urinary tract Normal points of narrowing (ureteropelvic and ureterovesical junctions, bladder neck, and urethral meatus) are common sites of obstruction Above the level of the bladder unilateral dilatation of the ureter (hydroureter) and renal pyelocalyceal system (hydronephrosis) Lesions at or below the level of the bladder bilateral involvement *Harrison’s

Etiology Hydronephrosis in utero May be associated with oligohydramnios and associated fetal respiratory complications. Posterior urethral valves - most common cause of bilateral hydronephrosis in boys Childhood causes Congenital malformations (narrowing of the ureteropelvic junction and anomalous (retrocaval) location of the ureter) Vesicoureteral reflux

Incidence and Epidemiology Fetal hydronephrosis diagnosed in 1 of 500 routine prenatal ultrasounds majority resolves by birth or within the first year of life fetal intervention rarely necessary, only considered in cases of bilateral hydronephrosis and severe oligohydramnios Following birth, severe hydronephrosis may be appreciated as a palpable abdominal mass *Schwartz’s

Incidence and Epidemiology Bilateral hydronephrosis renal ultrasound and VCUG should be obtained shortly after birth Unilateral hydronephrosis both studies can be obtained electively at approximately 1 month of life Higher risk for pyelonephritis diagnosed with unilateral or bilateral hydronephrosis: antibiotic prophylaxis (i.e., amoxicillin, 10 mg/kg per 24 hours) Pyelonephritis during the first year of life: kidney is still immature leads to permanent deterioration in renal function *neonates with hydronephrosis are at a higher risk for pyelonephritis

Ultrasound Severity should be graded from 1 to 4 using the Society for Fetal Urology grading scale GRADE OF HYDRONEPHROSIS CENTRAL RENAL COMPLEX RENAL PARENCHYMAL THICKNESS Intact Normal 1 Slight Splitting 2 Evident splitting, complex confined within renal border 3 Wide splitting pelvis dilated outside renal border, calyces uniformly dilated 4 Further dilatation of pelvis and calyces (calyces may appear convex) Thin

Voiding Cystourethrogram all cases of congenital hydronephrosis and in any child with ureteral dilatation dilation is secondary to vesicoureteral reflux in 15% of cases rule out urethral obstruction In boys; particularly in cases of suspected posterior urethral valves infravesical obstruction Infants - bladder may be palpable because of chronic distention and incomplete emptying Older children - decreased flow with a normal bladder contraction; urinary flow rate can be measured noninvasively with a urinary flowmeter urethral stricture or an obstructive urethral lesion urethra cannot be catheterized to obtain a VCUG

Excretory Urogram plain film of the abdomen infravesical obstruction calculi, spinal abnormalities, and an abnormal intestinal gas pattern or severe constipation infravesical obstruction bladder wall is irregular or trabeculated because of detrusor hypertrophy Postvoid film - show residual bladder urine Ureteral obstruction - collecting system is dilated above the obstruction and the calyces are blunted

MR Urography newest study used to evaluate suspected upper urinary tract pathology *utilizes the sensitivity of MR imaging to demonstrate fluid (urine), producing urogram-like pictures without the need for contrast media provides superb images of the pathology Method: child is hydrated and given intravenous furosemide gadolinium-DTPA is injected routine T1-weighted and fat-suppressed fast spin-echo T2-weighted imaging is performed through the kidneys, ureters, and bladder * Smith

Computed Tomography Non-contrast spiral CT of the abdomen and pelvis children with a suspected ureteral calculus standard method of demonstrating whether a calculus (or calculi) is present, its location, and whether there is significant proximal hydronephrosis

URETEROPELVIC JUNCTION OBSTRUCTION

URETEROPELVIC JUNCTION OBSTRUCTION An obstruction of the flow of urine from the renal pelvis to the proximal ureter Resultant back pressure within the renal pelvis may lead to progressive renal damage and deterioration

Incidence and Epidemiology ~ 1 in 100 pregnancies 1 in 500 are later diagnosed with significant urologic problems Found in ~ 50% of patients diagnosed with antenatal hydronephrosis M:F = 3-4:1 Left kidney > Right kidney UPJ obstruction is less common in adults than in children but is not rare in either population

INTRINSIC OBSTRUCTION SECONDARY UPJ OBSTRUCTION Etiology Scarring of ureteral valves Stenosis INTRINSIC OBSTRUCTION Asymmetry of ureteral wall musculature Abnormal peristalsis URETERAL HYPOPLASIA Prior surgery / Failure to repair 1° UPJ OBstruction Ureteral-wall and periureteral scar formation SECONDARY UPJ OBSTRUCTION

Clinical Presentation Back pain Blood in the urine (hematuria) Failure to thrive Flank pain Flank mass Kidney infection (pyelonephritis) Urinary tract infection (UTI)

Ancillary Procedures CBC count Coagulation profile Electrolyte level BUN Creatinine Urine culture

Ancillary Procedures Intravenous pyelogram demonstrating ureteropelvic junction obstruction with dilatation of the collecting system and lack of excretion of contrast

Medical Treatment Currently, medical therapy is unavailable for the treatment of both adult and pediatric cases of UPJ obstruction Antibiotics Prevent infection Monitored with renal ultrasound every 3 to 6 months

Surgical Treatment Indicated: UPJ obstruction causes a significant reduction in renal function Pyeloplasty Remove the obstruction Improve urine flow Reduce the risk for kidney damage. Pyeloplasty Involves removing the blockage and reattaching the ureter to the renal pelvis Temporary device that holds the ureter open (stent) may be inserted to drain the kidney Long-term success rates exceeds 95%

VESICOURETERAL REFLUX

VESICOURETERAL REFLUX Characterized by the retrograde flow of urine from the bladder to the kidneys. Associated with UTI, hydronephrosis, and abnormal kidney development (renal dysplasia)

Incidence and Epidemiology 17-37% in the pediatric population. ~ 20-30% of children with VUR present with renal lesions 5th most common cause of chronic renal insufficiency in children VUR is more prevalent in male newborns BUT, VUR seems to be 5-6 times more common in females older than one year than in males

Incidence and Epidemiology Has a definite genetic component MOA of inheritance remains unknown

Vesicoureteral Reflux

Etiology Primary causes Secondary causes Short or absent intravesical ureter Absence of adequate detrusor backing Lateral displacement of the ureteral orifice Abnormal configuration of the ureteral orifice (eg, stadium, horseshoe, golf hole) Secondary causes Cystitis or UTI Bladder outlet obstruction Detrusor instability Duplicated collecting system Paraureteral (Hutch) diverticulum

Grading of Reflux Grade I results in urine reflux into the ureter only. Grade II results in urine reflux into the ureter and the renal pelvis, without distention (hydronephrosis). Grade III results in urine reflux into the ureter and the renal pelvis, causing mild hydronephrosis. Grade IV results in moderate hydronephrosis. Grade V results in severe hydronephrosis and twisting of

Diagnosis Cystogram (also called cystourethrogram) Voiding cystourethrogram (VCUG) Bladder ultrasound to detect abnormalities that cause reflux Renal ultrasound and renal scan to evaluate hydronephrosis, kidney growth, and scarring

Clinical Presentation NEONATES Respiratory distress Persistent vomiting Failure to thrive Renal failure Flank masses Urinary ascites Severe UTI OLDER CHILDREN Symptoms of UTI Urgency Frequency Dysuria Nocturnal and diurnal enuresis Other constitutional symptoms include: Failure to thrive GI disturbances (eg. nausea, vomiting)

Treatment The goals of medical intervention in patients with VUR: To allow normal renal growth To prevent UTI and pyelonephritis To prevent renal failure. **Initiate medical management in prepubertal children with grades I-III reflux and most children with grade IV reflux.

Surgical Treatment Relative indications Grades IV and V reflux Persistent reflux despite medical therapy (beyond 3 y) Breakthrough UTIs in patient who are receiving antibiotic prophylaxis Lack of renal growth Multiple drug allergies

Surgical Treatment Absolute indications Medical noncompliance Breakthrough pyelonephritis Progressive renal scarring in patients receiving antibiotic prophylaxis Associated ureterovesical junction abnormality

Surgical Treatment Ureteral Reimplantation or Ureteroneocystostomy Indicated as a primary procedure if the patient has significant vesicoureteral reflux in the lower pole moiety and a well-functioning upper pole moiety and/or significant contralateral vesicoureteral reflux This operation is commonly delayed until the child is older (aged approximately 2 y/o) However, this operation should be performed before the child is toilet trained since it is rather extensive surgery

Complications Bleeding Infection Urinary leakage and bladder spasms shortly after the surgery (usually resolve in 2 to 3 weeks) Ureteral obstruction Persistent reflux

URETEROCELE

URETEROCELE Saccular out-pouching of the distal ureter into the urinary bladder Arise from abnormal embryogenesis, with anomalous development of the intravesical ureter, the kidney, and the collecting system May be asymptomatic or may cause a wide range of clinical signs and symptoms, from recurrent cystitis to bladder outlet obstruction

Types of ureteroceles classified by their association with the renal unit Single-system ureteroceles associated with a single kidney, a single collecting system, and a solitary ureter Duplex-system ureteroceles associated with kidneys that have a completely duplicated collecting system and 2 ureters. Orthotopic ureterocele orifice is located in a normal anatomic (orthotopic) position within the bladder usually arises from a single renal unit with one collecting system and is more common in adults Ectopic ureterocele orifices are located in an ectopic position, such as the bladder neck or urethra arise from the upper pole moiety of a duplicated collecting system and are more common in the pediatric population

Classification based on the features of the affected ureteral orifice Stenotic ureteroceles located inside the bladder with an obstructing orifice Sphincteric ureterocele refers to those that lie distal to the internal sphincter the ureterocele orifice may be normal or patulous, but the distal ureter leading to it becomes obstructed by the activity of the internal sphincter Sphincterostenotic ureteroceles have characteristics of both stenotic and sphincteric ureteroceles Cecoureteroceles elongated beyond the ureterocele orifice by tunneling under the trigone and the urethra

Etiology Several theories exist, including: obstruction of the ureteral orifice incomplete muscularization of the intramural ureter excessive dilatation of the intramural ureter during the development of the bladder and trigone Obstruction of the ureteral orifice during embryogenesis, with incomplete dissolution of the Chwalla membrane the most commonly accepted theory behind ureterocele formation Chwalla membrane primitive thin membrane that separates the ureteral bud from the developing urogenital sinus failure to completely perforate during development of the ureteral orifice is thought to explain the occurrence of a ureterocele

Epidemiology 1 in every 4000 children Most commonly in white persons F:M ratio - 4-7:1 Although a slight left-sided preponderance appears to exist, approximately 10% of ureteroceles occur bilaterally Ectopic ureteroceles has been reported to be approximately 80% in most pediatric series Similarly, approximately 80% of ureteroceles are associated with the upper pole moiety of a duplex system Single-system ectopic ureteroceles are uncommon and are most often found in males

Clinical Presentation Urinary tract infection Urosepsis Obstructive voiding symptoms Urinary retention Failure to thrive Hematuria Cyclic abdominal pain Ureteral calculus

Ancillary Procedures Laboratory Studies Urinalysis Urine culture Complete blood cell count Serum chemistries, especially BUN and serum creatinine Blood cultures Fungal cultures: obtained in infants who have been on long-term antibiotic therapy or in immunocompromised patients with clinical evidence of UTI

Ancillary Procedures Renal or bladder ultrasonography First-line imaging study for evaluating the upper and lower urinary tract in the pediatric population Seen as a fluid-filled cystic intravesical mass Aka "cyst within a cyst"

Ancillary Procedures Voiding cystourethrography Appears as a smooth, round filling defect along the base of the bladder

Ancillary Procedures Intravenous pyelography Useful for delineating renal anatomy and providing a subjective estimation of relative renal function The following may be seen on IVP: Hydronephrosis, revealing dilatation of collecting system Hydronephrotic upper pole displacing the lower pole moiety laterally and inferiorly (ie, the "drooping lily") Ureteral displacement by the hydroureter or hydronephrotic upper pole moiety Cobra-head extension of the distal ureter (ureterocele) (seen in adults)

Ancillary Procedures Cystoscopy, vaginoscopy, or retrograde pyelography Endoscopic procedures that allow direct inspection and examination of the lower urinary tract, as well as the female genitalia For optimal demonstration of a ureterocele, one must examine the bladder when it is both full and empty When radiologic suspicion of a ureterocele in an adult is aroused, cystoscopy often confirms radiographic findings If clinically indicated, the ureterocele may be treated with endoscopic incision or unroofing at the same setting

Medical Treatment Medical Therapy Observation alone is rarely a good option in symptomatic ureteroceles Must rapidly initiate aggressive antibiotic therapy Antibiotics should be instituted during the initial diagnostic evaluation and during surgical intervention

Surgical Treatment Goals of treatment include the following: Control of UTI Preservation of renal function Protection of ipsilateral and contralateral renal units Maintenance of urinary continence

Surgical Treatment Surgical approach is selected based on the following: Age of the patient Size and location of ureterocele Degree of renal function Presence and degree of vesicoureteral reflux Comorbid conditions (risk of anesthesia)

Endoscopic incision Least invasive method for decompressing the ureterocele Ideal method for dealing with a neonate with ureterocele-induced obstructive uropathy and sepsis Definitive therapy in only 10-40% of patients with ectopic ureteroceles, compared to 90% of the patients with a single system intravesical ureterocele

Upper pole heminephrectomy and partial ureterectomy Involves removal of the upper pole of the kidney, as well as the affected proximal ureter to the level of iliac vessels Remaining distal ureterocele is not excised but rather is decompressed Definitive treatment in patients with an obstructed ectopic ureterocele and a dysplastic upper pole, but without associated vesicoureteral reflux Excellent first-line procedure for the child with a ureterocele that affects only the ipsilateral upper pole Good choice in the child with a ureterocele with only ipsilateral renal involvement (which may include upper pole obstruction and lower pole reflux, for example)

Ureteropyelostomy Operation that joins the upper pole ureter to the lower pole renal pelvis Preferred if the affected renal unit demonstrates significant function Alternatively, a high ureteroureterostomy may also be performed This is true for both pediatric and adult populations

Excision of the ureterocele and ureteral reimplantation Indicated as a primary procedure if the patient has significant vesicoureteral reflux in the lower pole moiety and a well-functioning upper pole moiety and/or significant contralateral vesicoureteral reflux This operation is commonly delayed until the child is older (aged approximately 2 y/o) However, this operation should be performed before the child is toilet trained since it is rather extensive surgery

Nephroureterectomy Performed in patients with single system ureterocele and a nonfunctioning kidney The traditional method of correcting an ectopic ureterocele in a duplex system has been to perform a total reconstruction

Complications Endoscopic incision of ureterocele Iatrogenic VUR occurs in 40-50% of pediatric patients This is infrequently definitive therapy, except in cases of a single system intravesical ureterocele Upper pole heminephrectomy Highest risk of intraoperative blood loss Vascular compromise of lower pole with potential loss of renal function Need for further lower tract reconstruction due to persistent reflux, infection, or failure to decompress the ureterocele Excision of ureterocele and ureteral reimplantation Problematic hematuria and/or bladder spasms Damage to bladder neck or continence mechanism Injury to the contralateral ureteral orifice Compromise of blood supply to the lower pole ureter

POSTERIOR URETHRAL VALVE

POSTERIOR URETHRAL VALVE Obstructive congenital defect caused by a malformation of the posterior urethra Most common cause of lower urinary tract obstruction in male neonates Incidence is 1 per 8,000 to 1 per 25,000 live births Cause of renal insufficiency in approximately 10-15% of children undergoing renal transplant 1/3 of patients born with PUV progress to ESRD Diagnosis is usually made before birth or at birth

Embryogenesis The most caudal end of the Wolffian duct is absorbed into the primitive cloaca at the site of the future verumontanum in the posterior urethra In normal healthy males, the remnants of this process are the posterior urethral folds, called plicae colliculi. Histological studies  PUVs are formed at approximately 4 weeks' gestation, as the Wolffian duct fuses with the developing cloaca Degree of obstruction varies depending on the configuration of the obstructive membrane within the urethra May present with severe pulmonary distress Due to underdevelopment of the lung caused by oligohydramnios

Clinical Presentation Poor fetal breathing movements Small chest cavity Abdominal mass (ascites) Potter facies Limb deformities (skin dimpling) Indentation of the knees and elbows due to compression within the uterus

Ancillary Procedures Creatinine and BUN obtained at least 24 hours after birth provides a gross estimation of kidney function Infant’s Glomerular filtration rate VCUG (voiding cystourethrogram) or direct endoscopic visualization

Treatment Urethral catheter relief of urinary obstruction Vesicostomy and then valve ablation making a stoma in the urinary bladder, followed by closure of the stoma and valve ablation Pyelostomy and then valve ablation making a stoma in the pelvis of the kidney, followed by closure of the stoma and valve ablation Primary (transurethral) Valve ablation removal of the valves through urethra, without stoma

Complications Incontinence Infection VUR Progressive renal damage

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