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Obstructed Megaureter

Updated : August 30, 2023





Background

The dilated ureter is commonly referred to as a megaureter, and it is separated into main (congenital) & secondary categories. Both refluxing non-obstructing megaureters and non-refluxing obstructing megaureters are further split into each group. Based on radiographic & clinical observations, several differences are made. The term “obstructed megaureter” is misleading in and of itself because the majority of patients show just partial obstruction.

Despite the rarity of this entity, a thorough understanding can be applied to a wide range of ureteral anomalies since the concepts of its evaluation and care may be applicable to them all. There have been reports of congenital and acquired lesions that block the distal ureter, and in some cases, these lesions make the diagnosis difficult. Although a primarily blocked megaureter may subtend both a single collecting system & a duplicated system, it is most frequently connected to a single system.

Lesions could consist of the following:

  • Females are more likely to have ureteroceles, which are linked to the upper-pole ureter of a fully duplicated renal collecting system. This lesion is identified by the dilated distal ureter protruding into the bladder and urethral lumen.
  • The intrinsic filling deficiencies present in membranes, ureteral valves, & polyps distinguish these diseases from the primary megaureter. These tumors are uncommon.
  • Scarring may be a result of ureteral calculi that become affected in the distal ureter. Although the resulting ureteral constriction may mask the true diagnosis, there are universal therapeutic guidelines that apply regardless of the pathology.

On the basis of the definition of a dilated distal ureteral segment that inserts into a normal ureteral meatus, the diagnosis of an obstructed megaureter is made radiographically. These ureteral tunnels permit the retrograde passage of a ureteral catheter or probe, according to endoscopic results. However, when seen fluoroscopically, it is possible to see how the ureter’s peristalsis abruptly stops at the constriction.

The following anomalies may be connected:

  • Ureteral duplication
  • Renal dysplasia
  • Contralateral ureteroceles
  • Microcystitis
  • Contralateral renal agenesis

Renal & ureteral drainage should be considered as ureteral dilatation increases. Infections that do not respond to medicines alone may need drainage if megaureters are found in newborns and babies. A massively inflated ureter may also be decompressed with ureterostomy, nephrostomy, or colostomy drainage, which frequently enables a significant reduction in ureteral size & significantly decreases ureteral bulk after tailoring & reimplantation. Surgery might not be required in minor obstructions of the megaureter. In addition to monitoring symptoms and performing routine radiologic scanning, doctors can also give antibiotic prophylaxis.

Epidemiology

There is 1 obstructed megaureter for every 10,000 people. The ratio of men to women is 1.2-4.8:1. The ratio of left to right is 1.7 to 4:1. In 10%–20% of cases with obstructed megaureters, obstruction is bilateral.

The prevalence of primary obstructive megaureter (POM) in children has increased since the development of prenatal ultrasonography. This illness is relatively rare in adults and only manifests after years of asymptomatic remission without spontaneous regression.

Anatomy

Pathophysiology

Progressive dilatation results from partial occlusion in the aberrant distal section of the ureter. When the ureter can no longer accept resistance to urine outflow, hydronephrosis (i.e., dilatation of the calyces and renal pelvis) progresses, and pressure is subsequently transmitted more proximally.

Complete blockages are uncommon and are always diagnosed with a non-functioning renal unit. The ureteral orifice appears undamaged, & primary obstructed megaureters reach the bladder in a typical place on the trigone. Ectopic megaureters, which have their aberrant ends in the lower urinary system or mesonephric anlagen, shouldn’t be confused with this condition.

Etiology

A structural change in the distal ureter’s muscular layers that results in decreased or non-existent longitudinal muscle fibers, hyperplastic or hypertrophied circular muscle fibers, or elevated connective tissue accumulation is the primary cause of primary obstructing megaureter. These pathologically characterized abnormalities could be either an interruption of normal growth and development or the ureter’s intrauterine response to a continuous blockage.

There aren’t any animal studies of congenital megaureter, but Mortell et al. have created a rat model of prenatal exposure to Adriamycin/doxorubicin that could shed light on the cause of this developmental problem.

Genetics

Prognostic Factors

According to research, surgical results are 98 percent successful across all significant series. Failures frequently involved nontapered reimplants and took the appearance of reflux. Reoperation using tailoring and a second neocystostomy is always successful. Children who are sick when they are seen may have recurrent UTI episodes.

To lessen the effect of infection on renal growth, give these patients an extended prophylactic. In addition, place a focus on UTI surveillance throughout pregnancy in female patients who are of reproductive age. Since the two probable long-term problems associated with primary obstructed megaureter are renal dysplasia & infection with concomitant renal insufficiency, kidney function is the important factor in determining prognosis.

Clinical History

Clinical History

In as many as 1 out of every 100 infants, prenatal ultrasonography detects a sign of an underlining genitourinary problem; the majority of these cases are hydronephrosis. Since the development of fetal ultrasonography, the clinical manifestations of primary megaureter, which is less frequent, include the following:

  • Urolithiasis
  • Abdominal mass
  • Pelvic or abdominal pain
  • Fever with unknown causes
  • Sepsis
  • Failure to thrive.
  • Flank mass
  • Pyuria
  • Hematuria
  • Urinary system infection

On imaging tests (such as kidney, CT scanning, ultrasonography, bladder, ureter radiography, and bone scan) carried out for various reasons in children, a megaureter may also be accidentally discovered.

Physical Examination

Age group

Associated comorbidity

Associated activity

Acuity of presentation

Differential Diagnoses

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Staging

Treatment Paradigm

Medical Therapy

Physicians may evaluate symptoms, conduct routine radiological imaging, and prescribe antibiotic treatment in moderate cases of obstruction of the megaureter. The prognosis is favorable, with improving or stable renal or ureteral dilatation and ongoing renal growth (after more than 8 years of follow-up).

The following antibiotics are used as prophylactic to these patients:

Surgical Therapy

Infections that do not respond to medicines alone may need drainage if megaureters are found in newborns and babies. Additionally, refluxing ureteroneocystostomy, ureterostomy, nephrostomy, or pyelostomy drainage may be used to decompress the massively dilated ureter, which frequently enables a significant decrease in ureteral size and significantly reduces ureteral bulk during both tailoring & reimplantation. For primary obstructive megaureter, endoscopy balloon dilation provides a minimally invasive treatment option with positive long-term outcomes.

According to Chiarenza et al., balloon dilation appears to be more effective if done early in childhood and is effective in short stenotic passages (5 mm), intermediate stenotic sections (5 mm-1 cm), and short stenotic tracts (5 mm) (age 3-7 months). The main objectives of surgery are to remove the obstruction, restore the collecting system to almost normal function, produce non-refluxing vesicoureteral reimplantation, & maintain kidney development without long-term problems.

The two primary surgical strategies with these objectives are as follows:

  • Ureteral tailoring or distal ureteral mobilization with excision of the obstructed portion & reimplantation (to ensure a non-refluxing tunnel)
  • The ureter has been extensively customized from the renal pelvis distally in order to theoretically restore normal peristalsis by reducing ureteral lumen diameter.

Both strategies produce exceptional long-term benefits in the hands of skilled practitioners. Statistics and clinical analysis do not reveal any significant differences. An intravesical ureteral reimplantation may be advantageous for patients who have substantial reflux or voiding problems. Patients who don’t experience reflux or voiding issues benefit equally from extravesical therapy.

When the first course of treatment is unsuccessful, laparoscopic-assisted extracorporeal ureteral tapering repair & ureteral extravesical reimplantation has been reported as safe alternative to open surgery. According to Rappaport et al., executing dismembered extravesical cross-trigonal ureteral reimplantation for young patients with obstructed megaureters can be done safely and successfully using both laparoscopic & robot-assisted techniques.

In a few cases, primary endoureterotomy combined with stenting in children has been reported satisfactorily. 90% of the cases in one series exhibited improvement, with 71% of cases reporting full resolution.

A straight nipple ureteroneocystostomy can be done on adults. Since there is no need to adjust the ureters or submucosal tunnels, this is technically easier to accomplish. A few publications with follow-ups of up to 36 months show that this approach has a high success rate in adults.

Preoperative Details

Verify the patients’ infection-free status before repair. Normal blood loss is minimal; therefore, transfusions are infrequently required.

Intraoperative Details

Remember the following:

  • The upper ureter, lower ureter, or entire ureter may be accessed through the incision. To move the enlarged ureter, use either extravesical and intravesical dissection individually or in combination.
  • When doing extensive tailoring, take special care to protect the ureteral blood flow, which is derived from the renal artery, aorta, gonadal artery, & internal iliac artery.
  • To prevent postoperative reflux, lengths of 4:1–6:1 are advised for neocystostomy tunnels.
  • The surgeon has the option to utilize ureter splints or drains following surgery.

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Stem Cell Transplant

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Medication

 

 

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References

https://emedicine.medscape.com/article/441734-treatment#d16

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Obstructed Megaureter

Updated : August 30, 2023




The dilated ureter is commonly referred to as a megaureter, and it is separated into main (congenital) & secondary categories. Both refluxing non-obstructing megaureters and non-refluxing obstructing megaureters are further split into each group. Based on radiographic & clinical observations, several differences are made. The term “obstructed megaureter” is misleading in and of itself because the majority of patients show just partial obstruction.

Despite the rarity of this entity, a thorough understanding can be applied to a wide range of ureteral anomalies since the concepts of its evaluation and care may be applicable to them all. There have been reports of congenital and acquired lesions that block the distal ureter, and in some cases, these lesions make the diagnosis difficult. Although a primarily blocked megaureter may subtend both a single collecting system & a duplicated system, it is most frequently connected to a single system.

Lesions could consist of the following:

  • Females are more likely to have ureteroceles, which are linked to the upper-pole ureter of a fully duplicated renal collecting system. This lesion is identified by the dilated distal ureter protruding into the bladder and urethral lumen.
  • The intrinsic filling deficiencies present in membranes, ureteral valves, & polyps distinguish these diseases from the primary megaureter. These tumors are uncommon.
  • Scarring may be a result of ureteral calculi that become affected in the distal ureter. Although the resulting ureteral constriction may mask the true diagnosis, there are universal therapeutic guidelines that apply regardless of the pathology.

On the basis of the definition of a dilated distal ureteral segment that inserts into a normal ureteral meatus, the diagnosis of an obstructed megaureter is made radiographically. These ureteral tunnels permit the retrograde passage of a ureteral catheter or probe, according to endoscopic results. However, when seen fluoroscopically, it is possible to see how the ureter’s peristalsis abruptly stops at the constriction.

The following anomalies may be connected:

  • Ureteral duplication
  • Renal dysplasia
  • Contralateral ureteroceles
  • Microcystitis
  • Contralateral renal agenesis

Renal & ureteral drainage should be considered as ureteral dilatation increases. Infections that do not respond to medicines alone may need drainage if megaureters are found in newborns and babies. A massively inflated ureter may also be decompressed with ureterostomy, nephrostomy, or colostomy drainage, which frequently enables a significant reduction in ureteral size & significantly decreases ureteral bulk after tailoring & reimplantation. Surgery might not be required in minor obstructions of the megaureter. In addition to monitoring symptoms and performing routine radiologic scanning, doctors can also give antibiotic prophylaxis.

There is 1 obstructed megaureter for every 10,000 people. The ratio of men to women is 1.2-4.8:1. The ratio of left to right is 1.7 to 4:1. In 10%–20% of cases with obstructed megaureters, obstruction is bilateral.

The prevalence of primary obstructive megaureter (POM) in children has increased since the development of prenatal ultrasonography. This illness is relatively rare in adults and only manifests after years of asymptomatic remission without spontaneous regression.

Progressive dilatation results from partial occlusion in the aberrant distal section of the ureter. When the ureter can no longer accept resistance to urine outflow, hydronephrosis (i.e., dilatation of the calyces and renal pelvis) progresses, and pressure is subsequently transmitted more proximally.

Complete blockages are uncommon and are always diagnosed with a non-functioning renal unit. The ureteral orifice appears undamaged, & primary obstructed megaureters reach the bladder in a typical place on the trigone. Ectopic megaureters, which have their aberrant ends in the lower urinary system or mesonephric anlagen, shouldn’t be confused with this condition.

A structural change in the distal ureter’s muscular layers that results in decreased or non-existent longitudinal muscle fibers, hyperplastic or hypertrophied circular muscle fibers, or elevated connective tissue accumulation is the primary cause of primary obstructing megaureter. These pathologically characterized abnormalities could be either an interruption of normal growth and development or the ureter’s intrauterine response to a continuous blockage.

There aren’t any animal studies of congenital megaureter, but Mortell et al. have created a rat model of prenatal exposure to Adriamycin/doxorubicin that could shed light on the cause of this developmental problem.

According to research, surgical results are 98 percent successful across all significant series. Failures frequently involved nontapered reimplants and took the appearance of reflux. Reoperation using tailoring and a second neocystostomy is always successful. Children who are sick when they are seen may have recurrent UTI episodes.

To lessen the effect of infection on renal growth, give these patients an extended prophylactic. In addition, place a focus on UTI surveillance throughout pregnancy in female patients who are of reproductive age. Since the two probable long-term problems associated with primary obstructed megaureter are renal dysplasia & infection with concomitant renal insufficiency, kidney function is the important factor in determining prognosis.

Clinical History

In as many as 1 out of every 100 infants, prenatal ultrasonography detects a sign of an underlining genitourinary problem; the majority of these cases are hydronephrosis. Since the development of fetal ultrasonography, the clinical manifestations of primary megaureter, which is less frequent, include the following:

  • Urolithiasis
  • Abdominal mass
  • Pelvic or abdominal pain
  • Fever with unknown causes
  • Sepsis
  • Failure to thrive.
  • Flank mass
  • Pyuria
  • Hematuria
  • Urinary system infection

On imaging tests (such as kidney, CT scanning, ultrasonography, bladder, ureter radiography, and bone scan) carried out for various reasons in children, a megaureter may also be accidentally discovered.

Medical Therapy

Physicians may evaluate symptoms, conduct routine radiological imaging, and prescribe antibiotic treatment in moderate cases of obstruction of the megaureter. The prognosis is favorable, with improving or stable renal or ureteral dilatation and ongoing renal growth (after more than 8 years of follow-up).

The following antibiotics are used as prophylactic to these patients:

Surgical Therapy

Infections that do not respond to medicines alone may need drainage if megaureters are found in newborns and babies. Additionally, refluxing ureteroneocystostomy, ureterostomy, nephrostomy, or pyelostomy drainage may be used to decompress the massively dilated ureter, which frequently enables a significant decrease in ureteral size and significantly reduces ureteral bulk during both tailoring & reimplantation. For primary obstructive megaureter, endoscopy balloon dilation provides a minimally invasive treatment option with positive long-term outcomes.

According to Chiarenza et al., balloon dilation appears to be more effective if done early in childhood and is effective in short stenotic passages (5 mm), intermediate stenotic sections (5 mm-1 cm), and short stenotic tracts (5 mm) (age 3-7 months). The main objectives of surgery are to remove the obstruction, restore the collecting system to almost normal function, produce non-refluxing vesicoureteral reimplantation, & maintain kidney development without long-term problems.

The two primary surgical strategies with these objectives are as follows:

  • Ureteral tailoring or distal ureteral mobilization with excision of the obstructed portion & reimplantation (to ensure a non-refluxing tunnel)
  • The ureter has been extensively customized from the renal pelvis distally in order to theoretically restore normal peristalsis by reducing ureteral lumen diameter.

Both strategies produce exceptional long-term benefits in the hands of skilled practitioners. Statistics and clinical analysis do not reveal any significant differences. An intravesical ureteral reimplantation may be advantageous for patients who have substantial reflux or voiding problems. Patients who don’t experience reflux or voiding issues benefit equally from extravesical therapy.

When the first course of treatment is unsuccessful, laparoscopic-assisted extracorporeal ureteral tapering repair & ureteral extravesical reimplantation has been reported as safe alternative to open surgery. According to Rappaport et al., executing dismembered extravesical cross-trigonal ureteral reimplantation for young patients with obstructed megaureters can be done safely and successfully using both laparoscopic & robot-assisted techniques.

In a few cases, primary endoureterotomy combined with stenting in children has been reported satisfactorily. 90% of the cases in one series exhibited improvement, with 71% of cases reporting full resolution.

A straight nipple ureteroneocystostomy can be done on adults. Since there is no need to adjust the ureters or submucosal tunnels, this is technically easier to accomplish. A few publications with follow-ups of up to 36 months show that this approach has a high success rate in adults.

Preoperative Details

Verify the patients’ infection-free status before repair. Normal blood loss is minimal; therefore, transfusions are infrequently required.

Intraoperative Details

Remember the following:

  • The upper ureter, lower ureter, or entire ureter may be accessed through the incision. To move the enlarged ureter, use either extravesical and intravesical dissection individually or in combination.
  • When doing extensive tailoring, take special care to protect the ureteral blood flow, which is derived from the renal artery, aorta, gonadal artery, & internal iliac artery.
  • To prevent postoperative reflux, lengths of 4:1–6:1 are advised for neocystostomy tunnels.
  • The surgeon has the option to utilize ureter splints or drains following surgery.

 

 

 

 

https://emedicine.medscape.com/article/441734-treatment#d16

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