The vesico-ureteric junction in three cases of primary obstructive megaureter associated with ectopic ureteric insertion

Ureterovesical junction obstruction causes increment in smooth muscle contractility, and cholinergic and adrenergic activity in distal ureter of rabbits

BACKGROUND/PURPOSE

The controversy in management of primary obstructed megaureter necessitates further elucidation of the underlying pathophysiology. We evaluated smooth muscle contractility, and cholinergic, adrenergic and serotonergic activity of rabbit distal ureters after ureterovesical junction (UVJ) obstruction.

METHODS

Sham (SH) operation, partial obstruction (PO) and complete obstruction (CO) of the right UVJ were performed in rabbits. Three weeks later, distal ureters were isolated; spontaneous contractions (SC), contractile responses to electrical field stimulation (EFS), high KCl, carbachol, phenylephrine and serotonin were recorded.

RESULTS

SC amplitudes increased in CO compared to PO and SH (p<0.001). SC frequency was higher in CO (p<0.05). EFS-induced contraction amplitudes were greater in CO than other groups (p<0.05). High KCl-induced contractions were greater in CO (p<0.001) and PO (p<0.01). Carbachol-induced contractility was enhanced in CO and PO (p<0.05). Contractile response to phenylephrine was greater in CO than other groups (p<0.05). Serotonin induced contractile responses in CO and PO, greater in CO (p<0.05). UVJ obstruction also increased spontaneous contractility in contralateral PO and CO ureters.

CONCLUSIONS

UVJ obstruction increased spontaneous and neurotransmitter-induced contractions in an obstruction grade-dependent manner. Obstruction also altered contractility of the contralateral ureters. Our findings may serve to provide further understanding of the pathophysiology of megaureter.

Result of endoureterotomy in the management of primary obstructive megaureter in the first year of life: preliminary report

PURPOSE

The present study aimed to investigate the efficacy of endoureterotomy in patients who were less than 1-year-old with primary obstructive megaureter (POMU).

PATIENTS AND METHODS

Three of 10 patients with POMU aged between 2 and 12 months for whom conservative management was not applicable had recurrent urinary tract infection (UTI) and urosepsis, while the rest had decreased renal function. After obtaining the clinical history and performing physical examinations and imaging studies (ultrasonography, voiding cystourethrography (VCUG), radionuclide renal scan), the patients underwent endoureterotomy using a neonatal ureteroscope (4.5F) and Bugbee electrode with pure cutting current at the 6 o'clock position. A Double-J stent was inserted and removed 1 week later. This was followed by serial physical examination, renal function test, urine analysis, urine culture, and imaging studies in the 1st month and every 3 months after Double-J stent removal.

RESULTS

Hydroureteronephrosis was significantly decreased in nine patients. Postoperative VCUG revealed no sign of iatrogenic vesicoureteral reflux. In addition, a follow-up renal scan showed remarkable improvement in the renal function in the patients who had decreased renal function, except for one patient in whom uncontrolled urosepsis developed in the follow-up; the patient underwent cutaneous ureterostomy. No UTI was detected in the group who presented with recurrent UTI and urosepsis.

CONCLUSION

According to the results of our study, endoureterotomy may be an alternative in management of POMU. Of course, further studies with longer follow-up periods are needed to confirm the applicability of this method in patients younger than 1 year.

Severe primary obstructive megaureter in the first year of life: preliminary experience with endoscopic balloon dilation

BACKGROUND AND PURPOSE

Although conservative management is indicated in most cases of primary obstructed megaureter (POM), surgery is still indicated when POM is associated with increasing dilation, symptoms, or progressive renal damage. Surgery is associated with a significant rate of complications, however, especially in the case of very large ureter in the first year of life. A valid alternative could be endoscopic high pressure balloon dilation (EHPBD) of the vesicoureteral junction (VUJ). We report the first experience with EHPBD in patients under 1 year of age who were affected by severe POM.

PATIENTS AND METHODS

Five patients, aged between 6 and 12 months, were treated with EHPBD. In all patients, preoperative renal ultrasonography showed a distal ureteral dilation ≥15 mm that increased at later evaluations; an obstructive pattern was detected by preoperative diuretic renography. An 8-9,8 F cystoscope, and a 3F balloon catheter (balloon maximum diameter 4 mm) was used. The VUJ was dilated for 5 minutes at 12 to 14 atm. A 4.7F Double-J stent was then positioned and left in place for 6 to 8 weeks. Ultrasonography was performed every 3 months, and renography and voiding cystourethrography the fourth month after the EHPBD.

RESULTS

No operative complications were observed. All the patients showed an improvement at the ultrasonography postoperative follow-up, and there was no evidence of obstruction/reflux at the postoperative check up.

CONCLUSIONS

Our preliminary results seem to indicate that EHPBD is a feasible, safe, and successful procedure. It could play a role as a minimally invasive alternative to open surgery in cases of POM that necessitate intervention in the first year of life. Longer follow-up is necessary to verify the stability of these results.

Myocyte Apoptosis in Primary Obstructive Megaureters: The Role of Decreased Vascular and Neural Supply

PURPOSE

We compared myocyte apoptosis index, microvessel density and nerve supply as well as muscular and collagen composition in the obstructed ureteral endings of children with primary obstructive megaureter and normal controls.

MATERIALS AND METHODS

Tissue specimens were obtained during ureteral reimplantation in 16 patients with primary obstructive megaureter. For the control group normal ureteral endings were taken at autopsy from 19 age and sex matched children. In all specimens we determined the myocyte apoptosis index, number of CD31 positive microvessels, alpha-actin positive muscular component and number of nerve terminals. The collagen fibers were also specifically stained.

RESULTS

The myocyte apoptosis index was higher in obstructed vesicoureteral junctions (10.14%+/-1.03%) compared to controls (2.11%+/-0.21%, p<0.001). Mean number of vascular elements per microscopic field was lower in ureteral endings of patients with obstructive megaureter compared to controls (p<0.001). The number of nerve endings was also significantly lower in obstructed ureteral endings. There was a negative correlation between the number of microvessels and myocyte apoptosis index in both study groups. In obstructed megaureters the number of nerve endings was also negatively correlated with myocyte apoptosis index but positively correlated with the number of microvessels. In obstructed vesicoureteral junctions the proportion of muscular component was lower and the proportion of collagen fibers was higher compared to normal controls. Positive correlation was found between the myocyte apoptosis index and the percentage of collagenous component in both study groups.

CONCLUSIONS

Congenital defective vascular development may result in myocyte apoptosis, and reduction of neural elements and muscular components in obstructed vesicoureteral junctions. Subsequent substitution of connective tissue may lead to functional obstruction in primary obstructive megaureter.

Endoureterotomy for Treatment of Primary Obstructive Megaureter in Children

PURPOSE

To describe a new approach to the treatment of primary obstructive megaureter (POMU) using endoscopic endoureterotomy. The results obtained with this technique are reviewed with long-term follow-up.

PATIENTS AND METHODS

A total of 47 children (mean age 3.7 years) with 52 POMU units and a history of failed conservative management underwent endoureterotomy of obstructed juxtavesical and intramural ureter. A 3F Double-J ureteral stent was introduced up to the obstructed segment of ureter. Then a zebra catheter was inserted into the affected ureter beside the stent, followed by a neonatal-size ureteroscope. Following delineation of the length of the narrowed portion of the ureter, a guidewire with a plastic sheath replaced the zebra catheter. A longitudinal incision was made through the detrusor muscle at the 6 o'clock position, leaving the bladder adventitia untouched. The Double-J stent was left in place, while its distal tip was fixed by long nylon suture and single knot to the external genitalia to permit easy removal 1 week after the procedure.

RESULTS

With a mean follow-up of 39 months (range 14-62 months), no leakage, ureteral-orifice obstruction, or reflux was observed. The postoperative success rate was 90% (47 of 52 ureters), defined as resolution or decrease in hydroureteronephrosis and improvement or stability of renal function determined by renal scan. In 37 ureterorenal units (71%), there was complete resolution of hydroureteronephrosis.

CONCLUSIONS

On the basis of previous studies demonstrating the value of endoureterotomy with stenting for the treatment of benign ureteral strictures in adults, we developed a modified endoscopic approach for the treatment of POMU and applied this technique in meticulously selected cases. Our results showed that this approach is a valid option for the treatment of children with POMU.

Primary non-refluxing megaureters

Megaureters may be primary or secondary, and the dilatation may be due to obstruction or reflux, or both or neither. The cause of primary obstructed megaureter is the aperistaltic and narrowed pre-vesical portion of the ureter. The inner sheath of the terminal ureter generally shows a reduced amount of longitudinal smooth muscle bundles and an increased amount of collagen. Primary non-refluxing megaureters represent 23% of all prenatal diagnoses of hydronephrosis. They are more common in males and on the left side, and in 25% are bilateral. In older children they may become symptomatic. The diagnostic work up should include an ultrasound, a micturating cystourethrogram and an isotopic renogram. Most primary megaureters regress spontaneously or remain stable without compromising renal function, but 10-25% require surgery because of a progressive reduction in renal function or increasing dilatation, or because they become symptomatic. The basic principles of surgical repair include: resection of the obstructing segment, reduction in size of the dilated ureter, and re-implantation into the bladder using an anti-reflux technique.