7: Congenital anomalies of the upper urinary tract: UPJ obstruction, duplication anomalies, ectopic ureter, ureterocele, and ureteral anomalies Flashcards
What is the purpose of preoperative urodynamic evaluation in pediatric lower tract reconstructive procedures?
A. To identify candidates for surgery
B. To understand LUT anatomy and dysfunction
C. To determine the patient’s willingness to perform CIC
D. To evaluate postoperative outcomes
B. Preoperative urodynamic evaluation, often combined with fluoroscopy, is critical to understand LUT dysfunction and anatomy.
Explanation: Preoperative urodynamic evaluation is important in pediatric lower tract reconstructive procedures as it provides important information on the patient’s bladder function and anatomy. This information is essential in planning and performing the surgical procedure to achieve the desired outcome.
What is the ideal bladder volume achieved through reconstruction in children?
A. 1 hour
B. 2 hours
C. 4 hours
D. 6 hours
C. The bladder volume achieved through reconstruction should accommodate urinary output for an acceptable period of time, usually 4 hours.
Explanation: The bladder volume achieved through reconstruction should be sufficient to accommodate urinary output for a reasonable period of time. This is typically around 4 hours, although it may vary depending on the patient’s age, size, and other factors.
What is the risk of using gastrointestinal segments for bladder augmentation?
A. Metabolic alkalosis
B. Increased risk of UTIs
C. Reduced bladder capacity
D. Ammonium resorption causing metabolic acidosis
D. Ammonium resorption can cause metabolic acidosis, particularly among patients with renal insufficiency, and increase the risk of kidney stones.
Explanation: One of the potential complications of using gastrointestinal segments for bladder augmentation is ammonium resorption, which can cause metabolic acidosis and increase the risk of kidney stones. Daily bladder irrigations may help reduce the risk of bladder stones and UTIs.
What is the risk associated with bladder perforations within the bowel segment after bladder augmentation?
A. Vague abdominal symptoms
B. Increased risk of bladder cancer
C. Reduced bladder capacity
D. Metabolic acidosis
A. Bladder perforations within the bowel segment may present with vague abdominal symptoms requiring a high index of suspicion.
Explanation: Bladder perforations within the bowel segment are a potential complication of bladder augmentation. They may present with vague abdominal symptoms and require a high index of suspicion for diagnosis. Cystogram, computed tomography cystogram, or emergent surgical exploration may be necessary to diagnose this complication.
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FIG. 7.1 A proposed categorization of genital and renal anomalies in females. See text for details. Source: (From Magee MC, Lucey DT, Fried FA. A new embryologic classification for urogynecologic malformations: the syndromes of mesonephric duct induced Müllerian deformities. J Urol 1979;121:265-267.)
What is renal agenesis?
a. An acquired condition of the kidneys
b. A congenital absence of one or both kidneys
c. A condition that causes kidney enlargement
d. A condition that causes kidney stones
b. A congenital absence of one or both kidneys.
Explanation: Renal agenesis is a congenital anomaly that results in the absence of one or both kidneys, caused by developmental failures of the ureteral bud and metanephric mesenchyme.
What happens in bilateral renal agenesis?
a. The kidney function decreases significantly
b. The condition is asymptomatic
c. It causes oligohydramnios and pulmonary hypoplasia, which can be fatal
d. The kidneys enlarge due to compensatory hypertrophy
c. It causes oligohydramnios and pulmonary hypoplasia, which can be fatal.
Explanation: In bilateral renal agenesis, both kidneys are absent, leading to a severe reduction in amniotic fluid levels (oligohydramnios) and underdevelopment of the lungs (pulmonary hypoplasia), which can be fatal.
Which of the following abnormalities is frequently associated with unilateral renal agenesis?
a. Ureteropelvic junction obstruction
b. Bladder cancer
c. Hydronephrosis of both kidneys
d. Polycystic kidney disease
a. Ureteropelvic junction obstruction.
Explanation: Unilateral renal agenesis is frequently associated with contralateral ureteral abnormalities, including ureteropelvic junction (UPJ) obstruction (11%), ureterovesical junction (UVJ) obstruction (7%), and vesicoureteral reflux (VUR) (30%).
When should a voiding cystourethrogram (VCUG) be considered in a patient with unilateral renal agenesis?
a. If the patient has bilateral renal agenesis
b. If the patient has hydronephrosis or hydroureter in the solitary kidney
c. If the patient has no symptoms
d. If the patient has a normal ultrasound
b. If the patient has hydronephrosis or hydroureter in the solitary kidney.
Explanation: In unilateral renal agenesis, consider a voiding cystourethrogram (VCUG) if hydronephrosis or hydroureter is present in the solitary kidney due to the high coincidence of vesicoureteral reflux (VUR), particularly in this patient population.
Which of the following genital duct abnormalities is present in girls with unilateral renal agenesis?
a. Vasal agenesis
b. Bicornuate uterus with absent or underdeveloped ipsilateral uterine horn and fallopian tube
c. Hypospadias
d. Cryptorchidism
b. Bicornuate uterus with absent or underdeveloped ipsilateral uterine horn and fallopian tube.
Explanation: Ipsilateral genital duct abnormalities are present in 10%–15% of boys and 25%–50% of girls with unilateral renal agenesis. Girls may have a unicornuate or bicornuate uterus with absent or underdeveloped ipsilateral uterine horn and fallopian tube.
What is a horseshoe kidney?
a. A congenital anomaly in which the kidneys are absent
b. A congenital anomaly in which the kidneys are fused together
c. A condition in which the kidneys are enlarged
d. A condition in which the kidneys are displaced from their normal position
b. A congenital anomaly in which the kidneys are fused together.
Explanation: Horseshoe kidney is a congenital anomaly in which the two kidneys are fused together at their lower poles, forming a horseshoe shape.
What is the estimated incidence of horseshoe kidney?
a. 1 in 40 births
b. 1 in 400 births
c. 1 in 4,000 births
d. 1 in 40,000 births
b. 1 in 400 births.
Explanation: Horseshoe kidney is the most common renal fusion anomaly with an estimated incidence of 1 in 400 births.
Where is the isthmus located in a horseshoe kidney?
a. At the upper poles of the kidneys
b. At the lower poles of the kidneys
c. Between the renal pelvis and ureter
d. Along the anterior surface of the kidneys
b. At the lower poles of the kidneys.
Explanation: Anatomically, horseshoe kidneys have a parenchymatous isthmus connecting the right and left renal moieties, typically at the L3–L4 level.
What other congenital anomalies are commonly associated with horseshoe kidney?
a. Congenital absence of the testes
b. Down syndrome
c. Hypospadias or undescended testis
d. Congenital heart defects
c. Hypospadias or undescended testis.
Explanation: Approximately 30% of patients with horseshoe kidney have other congenital anomalies, notably Turner syndrome, hypospadias or undescended testis (5%), mullerian abnormalities (5%), VUR (50%), and UPJ obstruction (UPJO).
Why are children with horseshoe kidney at increased risk for stones and upper tract infection?
a. Due to obstruction of the ureters
b. Due to relative stasis caused by nondependent ureteral insertion
c. Due to enlargement of the kidneys
d. Due to displacement of the kidneys from their normal position
b. Due to relative stasis caused by nondependent ureteral insertion.
Explanation: Unobstructed dilation caused by nondependent ureteral insertion is common in horseshoe kidney. Because of relative stasis, children with horseshoe kidney are at increased risk for stones and upper tract infection.
What is a crossed ectopic kidney?
a. A kidney that is absent at birth
b. A kidney positioned contralateral to its ureteral insertion in the bladder
c. A kidney with an enlarged renal pelvis
d. A kidney with a congenital obstruction of the ureter
b. A kidney positioned contralateral to its ureteral insertion in the bladder.
Explanation: Crossed ectopia refers to a kidney that is positioned contralateral to its ureteral insertion in the bladder.
What is the most common orientation of the ectopic kidney in crossed ectopia?
a. The ectopic kidney crosses from right to left
b. The ectopic kidney crosses from left to right
c. The ectopic kidney is located superior to the normal kidney
d. The ectopic kidney is located posterior to the normal kidney
b. The ectopic kidney crosses from left to right.
Explanation: In most cases of crossed ectopic kidney, the ectopic kidney crosses from left to right, and the ectopic moiety is positioned inferior to the normal moiety.
What is the most common presentation of crossed ectopic kidney?
a. Hematuria
b. Abdominal pain
c. Urinary tract infections
d. Nausea and vomiting
c. Urinary tract infections.
Explanation: Crossed ectopic kidneys are usually asymptomatic and discovered incidentally, but a minority of patients present with urinary tract infections (UTIs), stones, or hematuria.
Are the ureteral orifices normal in crossed ectopic kidney?
a. No, they are typically ectopic
b. No, they are typically obstructed
c. Yes, they are normal and orthotopic
d. Yes, but they are smaller than normal
c. Yes, they are normal and orthotopic.
Explanation: In all types of crossed ectopic kidney, the ureteral orifices are normal and orthotopic.
What is the characteristic feature of crossed ectopic kidney on imaging?
a. An enlarged renal pelvis
b. The presence of cysts within the kidney
c. Absence of the renal vein
d. The position of the ectopic kidney opposite to its ureteral insertion
d. The position of the ectopic kidney opposite to its ureteral insertion.
Explanation: Crossed ectopic kidney is diagnosed by imaging, and the characteristic feature is the position of the ectopic kidney opposite to its ureteral insertion in the bladder.
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FIG. 7.2 Crossed renal ectopia with fusion (A–F).
What is renal duplication?
a. A congenital anomaly in which the kidney is absent
b. A congenital anomaly in which the kidney is enlarged
c. A congenital anomaly in which there are two ureteral buds instead of one
d. A congenital anomaly in which the kidney is displaced from its normal position
c. A congenital anomaly in which there are two ureteral buds instead of one.
Explanation: Renal duplication is a congenital anomaly in which there are two ureteral buds instead of one.
What is incomplete pyeloureteral duplication?
a. Duplication of the kidney and the ureter
b. Branching of a single ureteral bud resulting in a single ipsilateral orifice
c. The presence of two separate ureteral buds from the same mesonephric duct
d. A relatively cephalad and laterally positioned orifice draining the lower moiety
b. Branching of a single ureteral bud resulting in a single ipsilateral orifice.
Explanation: Branching of a single ureteral bud results in incomplete pyeloureteral duplication, characterized by a single ipsilateral orifice and bifid renal pelvis or Y-shaped ureter.
What is complete ureteral duplication?
a. Duplication of the kidney and the ureter
b. Branching of a single ureteral bud resulting in a single ipsilateral orifice
c. The presence of two separate ureteral buds from the same mesonephric duct
d. A relatively cephalad and laterally positioned orifice draining the lower moiety
c. The presence of two separate ureteral buds from the same mesonephric duct.
Explanation: Takeoff of two separate ureteral buds from the same mesonephric duct results in complete ureteral duplication, wherein a relatively cephalad and laterally positioned orifice drains the lower moiety (LM) and a more caudal and medial orifice drains the upper moiety (UM).
What is the LM ureter more prone to in complete ureteral duplication?
a. Distal obstruction
b. Vesicoureteral reflux
c. Ectopic ureteral insertion
d. Ureterocele
b. Vesicoureteral reflux.
Explanation: The LM ureter is more prone to vesicoureteral reflux via a shortened intramural tunnel length.
What is the UM ureter more prone to in complete ureteral duplication?
a. Distal obstruction
b. Vesicoureteral reflux
c. Ectopic ureteral insertion
d. Ureterocele
a. Distal obstruction.
Explanation: The UM ureter is more prone to distal obstruction and may be associated with a ureterocele or ectopic ureteral insertion.
What is a ureteral bud?
In the context of renal embryology, a ureteral bud is a small outgrowth from the mesonephric duct that gives rise to the ureter and renal collecting system. The ureteral bud interacts with the metanephric mesenchyme to induce the formation of the kidney.
What does caudal mean?
In anatomy and biology, caudal means situated towards or relating to the tail or posterior end of the body. It is the opposite of “cranial,” which means towards the head or anterior end of the body. In the context of renal embryology, “caudal” is often used to describe a position lower in the body or towards the back, as opposed to “cephalad,” which describes a position higher in the body or towards the front.
What is the main difference between congenital obstructive uropathy (COU) and postnatal acquired obstruction?
a. COU only affects one kidney, while postnatal acquired obstruction can affect both kidneys.
b. COU alters the growth and differentiation of the developing kidney, while postnatal acquired obstruction does not.
c. COU is usually asymptomatic, while postnatal acquired obstruction is associated with significant pain.
d. COU is caused by infection, while postnatal acquired obstruction is typically due to structural abnormalities.
b. COU alters the growth and differentiation of the developing kidney, while postnatal acquired obstruction does not.
Explanation: Congenital obstructive uropathy (COU) is distinct from postnatal acquired obstruction in that it alters the growth and differentiation of the developing kidney.
What are the key pathological patterns associated with COU?
a. Inflammation and necrosis
b. Cysts and tumor formation
c. Fibrosis and altered morphogenesis
d. Arterial sclerosis and aneurysm formation
c. Fibrosis and altered morphogenesis.
Explanation: Key pathological patterns associated with COU include fibrosis and altered morphogenesis, which can ultimately lead to dysplasia in severe cases.
Does postnatal correction of obstruction usually result in normalization of kidney function?
a. Yes, in all cases
b. No, but it always limits progression
c. No, because altered function and pathophysiological processes can continue
d. It depends on the type of obstruction and the age of the patient
c. No, because altered function and pathophysiological processes can continue.
Explanation: Postnatal correction of obstruction does not usually permit normalization but may limit progression. However, progression may continue because of altered function and ongoing pathophysiological processes.
Are affected kidneys in obstructive uropathy always abnormal on imaging?
a. Yes, in all cases
b. No, they may appear normal on imaging even with significant histologic abnormalities
c. No, they always show signs of obstruction on imaging
d. It depends on the severity of the obstruction and the age of the patient
b. No, they may appear normal on imaging even with significant histologic abnormalities.
Explanation: Biopsy studies have shown that even with normal uptake on nuclear imaging, affected kidneys may have significant histologic abnormalities.
What is the significance of early insults to normal kidney development in obstructive uropathy?
a. They do not have any long-term consequences
b. They increase the risk of kidney stones
c. They are associated with later progression to renal insufficiency
d. They only affect the growth of one kidney, not both
c. They are associated with later progression to renal insufficiency.
Explanation: It has been shown that early insults to normal kidney development are associated with later progression to renal insufficiency.
What is the most common form of pediatric upper urinary tract obstruction?
a. Ureterovesical junction obstruction (UVJO)
b. Ureteral duplication
c. Ureteropelvic junction obstruction (UPJO)
d. Ureteral stricture
c. Ureteropelvic junction obstruction (UPJO)
Explanation: Ureteropelvic junction is the most common form of pediatric upper urinary tract obstruction.
What is the typical presentation of UPJ obstruction?
a. Prenatal detection of hydronephrosis only
b. Symptomatic presentation of abdominal or flank pain only
c. Both prenatal detection of hydronephrosis and symptomatic presentation of abdominal or flank pain
d. Fever and urinary tract infection (UTI) only
: c. Both prenatal detection of hydronephrosis and symptomatic presentation of abdominal or flank pain.
Explanation: The clinical presentation of UPJ obstruction is most commonly through prenatal detection of hydronephrosis, but it can also present with symptomatic presentation of abdominal or flank pain.
What is Deitl’s crisis?
a. An episode of acute renal failure
b. A complication of UTI
c. An episode of colicky flank pain with nausea and vomiting
d. A type of urinary incontinence
c. An episode of colicky flank pain with nausea and vomiting.
Explanation: Abrupt onset of severe pain, frequently with nausea and vomiting that is colicky in nature, is the typical pattern of Deitl’s crisis, which can be seen in UPJ obstruction.
What is the gold standard for correcting UPJ obstruction?
a. Nephrectomy
b. Stenting
c. Balloon dilation
d. Dismembered pyeloplasty
d. Dismembered pyeloplasty.
Explanation: The gold standard for correcting UPJ obstruction is a dismembered pyeloplasty.
What are the clear indications for surgery in UPJ obstruction?
a. Markedly increased hydronephrosis, > 10% decrease in relative uptake on renography, and symptoms such as pain or UTI
b. Prenatal detection of any degree of hydronephrosis
c. Decrease in urinary output
d. Hematuria
a. Markedly increased hydronephrosis, > 10% decrease in relative uptake on renography, and symptoms such as pain or UTI.
Explanation: Clear indications for surgery in UPJ obstruction include markedly increased hydronephrosis, > 10% decrease in relative uptake on renography, and symptoms such as pain or UTI.
What is the cause of extrinsic UPJ obstruction?
a. Intrinsically abnormal proximal ureteral development
b. A developmental anomaly in the lower pole of the kidney
c. Blockage due to a tumor or foreign body
d. A stricture in the ureter
b. A developmental anomaly in the lower pole of the kidney.
Explanation: Extrinsic UPJ obstruction is often caused by a lower pole vessel of the kidney that creates a kinking of the ureter.
Can UPJ obstruction resolve spontaneously in infants?
a. Yes, in some cases
b. No, surgery is always required
c. It depends on the severity of the obstruction
d. Only if the obstruction is caused by an intrinsic abnormality
a. Yes, in some cases.
Explanation: Spontaneous resolution of UPJ obstruction is common in many infants.
What is the underlying etiology of UPJ obstruction?
a. Always due to an intrinsic abnormality of the ureter
b. Always due to an extrinsic obstruction
c. May be due to either an intrinsic or extrinsic cause
d. Due to a narrowing of the ureter at the ureterovesical junction
c. May be due to either an intrinsic or extrinsic cause.
Explanation: The underlying etiology of UPJ obstruction is variable and may be due to either an intrinsic or extrinsic cause.
What is the most common way that UPJ obstruction is diagnosed in children?
a. Through imaging during an episode of Deitl’s crisis
b. By presenting with symptoms of gastroenterologic problems
c. Through prenatal detection of hydronephrosis
d. Through a diuretic renogram
c. Through prenatal detection of hydronephrosis. Clinical presentation of UPJ obstruction is most commonly through prenatal detection of hydronephrosis, which is typically seen on an anatomic screening ultrasound performed at 20 weeks’ gestation. If hydronephrosis is detected, further monitoring of the dilation is warranted with serial ultrasonography.
Option a is incorrect because imaging during an episode of Deitl’s crisis may reveal increased dilation from a baseline study, but this is not the most common way that UPJ obstruction is diagnosed. Option b is incorrect because presenting with symptoms of gastroenterologic problems may lead to a missed diagnosis of UPJ obstruction. Option d is incorrect because although a diuretic renogram may be used to evaluate UPJ obstruction, it is not the most common way that it is diagnosed.
What are the key factors evaluated using diuretic renography for ureteropelvic junction obstruction (UPJ)?
A. The number of dilated renal calyces
B. The presence of lower pole vessel obstruction
C. The relative function of the affected kidney compared with the contralateral
D. The size of the dilation in the affected pelvis
C. The relative function of the affected kidney compared with the contralateral is one of the key factors evaluated using diuretic renography for UPJ obstruction. This helps to assess the degree of obstruction and guide management decisions. The washout time following Lasix administration is also evaluated. The number of dilated renal calyces and the size of the dilation in the affected pelvis may be assessed using ultrasound or other imaging modalities, but they are not key factors evaluated using diuretic renography. The presence of lower pole vessel obstruction may be a cause of extrinsic obstruction, but it is not directly evaluated using diuretic renography.
What is the recommended frequency of follow-up ultrasonography for conservative management of UPJ obstruction during the first year of life?
a. Every 6 months
b. Every 12 months
c. Every 3 months
d. Every 2 years
c. Every 3 months. According to the given information, a practical observation plan for conservative management of UPJ obstruction would include follow-up ultrasonography every 3 months during the first year of life.
What are the clear indications for surgery in a patient with UPJ obstruction?
a. Increased urine production, decreased renal function, and decreased AP diameter of the dilated pelvis
b. Markedly increased hydronephrosis, > 10% decrease in relative uptake on renography, and symptoms such as pain or UTI
c. Decreased urine production, increased renal function, and normal AP diameter of the dilated pelvis
d. Decreased urine production, decreased renal function, and normal AP diameter of the dilated pelvis
b. Markedly increased hydronephrosis, > 10% decrease in relative uptake on renography, and symptoms such as pain or UTI. According to the given information, clear indications for surgery in a patient with UPJ obstruction include markedly increased hydronephrosis, > 10% decrease in relative uptake on renography, and symptoms such as pain or UTI. Persistence of hydronephrosis with no improvement over time may also be an indication for intervention.
What is the recommended postoperative evaluation after a dismembered pyeloplasty?
a) Diuretic renogram after 3 months
b) Renal ultrasound after 1 week
c) MRI after 6 months
d) No postoperative evaluation is needed
a) Diuretic renogram after 3 months is the recommended postoperative evaluation after a dismembered pyeloplasty.
Explanation: Typical postoperative evaluation includes a renal ultrasound 4-8 weeks after surgery, and continued monitoring is reasonable. Some groups perform a diuretic renogram at 3 months, and if this drains well, discontinue further follow-up. However, ongoing monitoring of hydronephrosis for 2-5 years is prudent.
What are some potential complications of surgical management for UPJ obstruction?
a) Urinary leakage and development of a urinoma
b) Respiratory distress and cardiac arrhythmia
c) Dizziness and headache
d) Joint pain and muscle weakness
a) Urinary leakage and development of a urinoma are potential complications of surgical management for UPJ obstruction.
Explanation: Other potential complications of surgical management for UPJ obstruction include postoperative infection, which is common, and persisting obstruction, which is uncommon and may require replacement of a ureteral stent, balloon dilation, or reoperative pyeloplasty.
FIG. 7.3 Ultrasound appearance of UPJO.
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FIG. 7.4 Anderson-Hynes dismembered pyeloplasty. (A) Traction sutures are placed on the medial and lateral aspects of the dependent portion of the renal pelvis in preparation for dismembered pyeloplasty. A traction suture is also placed on the lateral aspect of the proximal ureter below the level of the obstruction. This suture will help maintain proper orientation for the subsequent repair. (B) The ureteropelvic junction is excised. The proximal ureter is spatulated on its lateral aspect. The apex of this lateral, spatulated aspect of the ureter is then brought to the inferior border of the pelvis while the medial side of the ureter is brought to the superior edge of the pelvis. (C) The anastomosis is performed with fine interrupted or running absorbable sutures placed full thickness through the ureteral and renal pelvic walls in a watertight fashion.
What is ureterovesical junction obstruction (UVJO)?
A. A wide, non-peristaltic segment of the intramural ureter causing a variable degree of upper tract obstruction.
B. A condition in which the ureter is too short.
C. A narrow, peristaltic segment of the intramural ureter causing a variable degree of upper tract obstruction.
D. A condition in which the ureter is located outside the bladder.
C. A narrow, peristaltic segment of the intramural ureter causing a variable degree of upper tract obstruction.
Explanation: UVJO, also referred to as primary obstructed megaureter, results from a narrow, aperistaltic segment of intramural ureter, causing a variable degree of upper tract obstruction.
What is the definition of a megaureter?
A. Hydroureter of < 7 mm, regardless of etiology.
B. Hydroureter of > 7 mm, regardless of etiology.
C. A condition in which the ureter is too short.
D. A condition in which the ureter is located outside the bladder.
: B. Hydroureter of > 7 mm, regardless of etiology.
Explanation: The term “megaureter” is used to describe hydroureter of ≥ 7 mm, regardless of etiology.
Which of the following is a common presentation of UVJO in infants or children?
A. Chest pain
B. Abdominal distension
C. Febrile UTI
D. Visual disturbance
C. Febrile UTI
Explanation: Infants or children may present with febrile UTI, sepsis, pain, stones, or microscopic hematuria.
What is the preferred management approach for children with UVJO who have no infections or functional loss?
A. Surgical intervention
B. Observation
C. Antibiotic treatment
D. Radiation therapy
B. Observation
Explanation: Even in the setting of delayed excretion on renogram, observation is the preferred management approach for children with UVJO who have no infections or functional loss.
When is definitive reconstruction indicated for UVJO?
A. Stone formation
B. Ipsilateral function under 40%
C. Progressive, unremitting dilation
D. All of the above
D. All of the above
Explanation: Indications for definitive reconstruction include recurrent or severe infection, ipsilateral function under 40%, and significant or sequential functional decline. Stone formation, pain, or progressive, unremitting dilation may also prompt surgery in some patients.