Keywords
ureteral reconstruction - ureteropelvic junction obstruction - tapered segment of
the descending colon - long ureteral stenosis
New Insights & the Importance for a Pediatric Surgeon
Long upper ureteral stenosis may require tissue interposition for successful repair.
Tapering a segment of the descending colon is simple and seems unaffected by mucus-related
complications.
Introduction
The surgical management of ureteral stenosis varies according to the level and length
of the defect. Short upper ureteral stenosis may be treated by excision and ureteroureterostomy
or ureterocalicostomy. Long upper ureteral stenosis requires more extensive intervention
such as transureteroureterostomy, renal auto-transplantation, tissue interposition
with gastrointestinal tract (GIT) segments or ureteral reconstruction using the ileum,
colon, appendix, and other tissue like buccal mucosal grafts,[1]
[2]
[3]
[4]
[5]
[6]
[7]
[8] or the Yang–Monti technique using transverse re-tubularized segments of the ileum.
Of these options, the Yang–Monti technique has been reported to be effective.[8]
The colon may have limited application for ureteral reconstruction in its original
form because the resulting segment will have a larger diameter and surface area because
it is generally wider and thicker than other tissues. However, in the presented case,
the descending colon was the most readily available tissue in close proximity to the
stenosed ureter and was reconfigured by tapering to create a substitute ureter.
In view of the previous surgical history of the presented case, involving two failed
left ureteropelvic junction (UPJ) obstruction repairs that resulted in extensive ureteral
stenosis of 5 cm, a tapered segment of the descending colon (TDC) was considered the
only viable option for ureteral reconstruction and demonstrated skillful application
of existing surgical techniques for treating a unique case of gross ureteral stenosis.
The outcome was successful and the patient has been well.
Case Report
The presented case is a biracial (Japanese/Caucasian) male, born at 38 weeks of gestation
by spontaneous vaginal delivery at a hospital overseas after an uneventful pregnancy.
Routine prenatal ultrasonography (US) showed no evidence of hydronephrosis. He was
born overseas weighing 2,800 g and grew steadily following standard growth curves
overseas until sudden onset of vomiting and abdominal pain at the age of 8 years that
was considered psychosomatic. Eventually, he was diagnosed with UPJ obstruction at
the age of 11 years (details unknown) and had open pyeloplasty for left UPJ obstruction
associated with left hydronephrosis, overseas. His postoperative course was complicated
by abdominal pain after removal of a double J stent (DJS) inserted intraoperatively.
A DJS was reinserted with resolution of symptoms. Transurethral retrograde pyelography
(RP) performed 3 months later at a hospital in Japan during a visit identified obstruction
at the ureteropelvic anastomosis (UPA). The Covid-19 pandemic prevented the family
from returning overseas and open redo pyeloplasty was performed retroperitoneally
elsewhere in Japan, 5 months after the initial operation that was performed overseas.
Unfortunately, transurethral RP at the time of postoperative DJS removal identified
re-obstruction of the UPA. He was referred for further management of recurrent UPJ
obstruction. At presentation when he was almost 13 years old, the RP identified a
5-cm-long stenosis at the UPA and hypoperistalsis of the UPJ and upper ureter ([Fig. 1A]). Dimercaptosuccinic acid (DMSA) scintigraphy revealed almost no difference in split
renal function (right/left uptake: 16.6/18.5% [ratio: 47.4:52.6%]). Options for surgical
intervention were limited because of the length of the stenosis causing UPJ obstruction,
and reconstruction of the upper ureter using the TDC was planned because of the proximity
of the descending colon. By this time, 3 months had elapsed since referral and he
was 13 years old.
Fig. 1 Upper ureteral reconstruction with a tapered segment of descending colon. (A) Preoperative retrograde pyelography revealed a 5-cm-long stenosis of the ureter
(white arrowheads). (B) An 8-cm-long descending colon (A) was isolated, tapered (red dotted line), sutured in a funnel shape, and then anastomosed to reconstruct the upper ureter.
The photograph shows the colon segment being grasped before being tapered and sutured
using a catheter as a temporary stent. (C) The final outcome with a double J stent, percutaneous nephrostomy tube, and retroperitoneal
drain.
Retroperitoneoscopic repair was planned initially, but it was converted to an open
procedure because of extensive adhesions. The ureter was dissected as far as the lower
pole of the kidney. The old UPA was exposed and the stenosed segment was excised.
Both cut ends of the ureter were thick, fibrosed, and bled easily, appearing macroscopically
to be severely inflamed. Some 3 cm of the inflamed lower ureter was also resected
([Fig. 1A]) until the ureter appeared healthier. Because the upper cut end of the old UPA was
no more than a fine opening ([Fig. 1B]), it was incised and the incision extended to the renal parenchyma. The mucous membranes
of the renal pelvis and calyces also appeared to be inflamed because they were friable
and coarse like the cut ends of the ureter, so they were everted to be in direct contact
with the TDC at the new anastomosis. After excising the stenosis, there was a 6-cm-long
defect requiring tissue interposition.
The peritoneum adjacent to the excised ureter was incised and a length of descending
colon was mobilized to the retroperitoneal space. The maximum diameter of the descending
colon mobilized was 3 cm. An 8-cm segment of the mobilized colon with intact blood
vessels was isolated, tapered, and sutured into a funnel shape with an upper diameter
of 2 cm and a lower diameter of 1 cm ([Fig. 1A, B]) around a 14-Fr catheter as a temporary stent. After colocolostomy, the descending
colon was returned to the abdominal cavity and the peritoneum closed carefully to
prevent vascular compromise. Because the lumen of the lower end of the ureter was
also narrow, the antimesenteric side of the ureter was incised until there was healthy,
well-preserved tissue that was wide enough for anastomosis to the TDC. A DJS (5 Fr,
26 cm) was placed between the renal pelvis and the bladder via the TDC. The ureter–TDC
and calyx–TDC anastomoses were performed with 5–0 absorbable interrupted sutures.
A 9-Fr percutaneous nephrostomy tube and a 15-Fr retroperitoneal drain were placed
([Fig. 1C]). The total operative time was 770 minutes.
The retroperitoneal drain was left in situ for longer than usual for fear of suture
failure at the anastomosis and was removed 12 days postoperatively when drainage decreased.
Contrast pyelography via the percutaneous nephrostomy tube the next day showed passage
through the calyx–TDC anastomosis but not through the ureter–TDC anastomosis ([Fig. 2A]). Clamping the nephrostomy tube was trialed on postoperative day 14, and gradually
extended until it was removed on day 19 without sequelae. The 5-Fr DJS was removed
transurethrally on day 49; good passage through the ureter–TDC anastomosis was identified
on RP ([Fig. 2B, C]). Diuretic renography performed 2 months postoperatively showed no obstruction on
the left side. Currently, he is symptom free after 18 months of follow-up.
Fig. 2 Postoperative urography. Smooth urine flow through the (A) calyx–tapered segment of descending colon (TDC) anastomosis 13 days postoperatively
and through the (B,C) ureter–TDC anastomosis 49 days postoperatively.
Discussion
The presented case posed problems for reconstructive surgery because of extensive
adhesions and long upper ureteral stenosis. An ileal conduit or the appendix accessed
intraperitoneally could be considered for primary repair, but a repeat intraperitoneal
procedure was essentially contraindicated by the two previous failed pyeloplasties.
Because of concern that another extensive intraperitoneal procedure may not proceed
well because of severe adhesions with an increased risk of complications such as bowel
obstruction,[7] postoperatively, the TDC was chosen specifically as the original strategy was to
use a retroperitoneal approach to avoid extensive adhesions expected to be present
after failed previous surgery and the descending colon was the closest readily available
tissue to the operative field. The TDC was also chosen because it was considered easier
than the re-tubularizing transverse colon segments, which, in the presented case,
would have required joining at least two segments of the re-tubularized colon in sequence
to create the required 6-cm length to bridge the gap in the upper ureter, increasing
risks of suture failure and anastomotic leakage because the colon was only 3 cm in
diameter. In addition, with the TDC, a ureter can be customized, in this case, into
a funnel shape required to connect the larger diameter of the pyelocalyx with the
smaller diameter of the ureter, effectively. In fact, the TDC resulted in a continuous
neoureter compared with a re-tubularized colon neoureter that would have been comprised
of segments.
Because the colon was used to reconstruct the upper ureter, mucus secretion was expected
to cause complications such as obstruction or calculus formation. However, in reports
of Yang–Monti[6]
[7]
[8] cases, when segments of the GIT were used to reconstruct a ureter, the re-tubularization
process seemingly disrupted the physiologic function of GIT segments with no complications
related to mucus or metabolic consequences of the absorption of substances in urine
being identified. In fact, an unexpected advantage of the TDC was efficient antegrade
urine flow due to the use of mucosal folds and muscles of the segment of the colon.
The mechanism by which the previous pyeloplasties failed can only be speculated about.
Dense fibrous adhesive tissue forming around the UPA, ischemia, foreign body reactions
to stents or sutures, missed crossing vessels, kinking of redundant pelvis tissue,
or even the use of electrocautery have all been implicated in the etiology of failed
pyeloplasty.[9] In the present case, no abnormally crossed vessels were identified and the old UPA
was not kinked. Histopathologic analysis was not performed because no surgical specimen
was collected from the old UPA; however, there was obvious scarring around the upper
ureter. Therefore, the probable cause of the long upper ureteral stenosis and failed
pyeloplasties was attributed to scarring of the old UPA.
Contact between the colonic mucosa and urine is a known risk factor for malignant
transformation.[10] However, there is evidence that the Yang–Monti technique may not be associated with
malignant transformation in the colon[7] and in reports of malignant transformation most patients were older than 50 years.[9] While malignant transformation can be symptomatic with fever of unknown origin,
localized discomfort, or abnormal serum biochemistry, routine screening with cystoscopy/colonoscopy
every 5 to 10 years or CT colonography every 5 years for patients ≥50 years with GIT
segment tissue interposition is recommended.[10]
[11] For the present case, magnetic resonance imaging may be more appropriate for investigating
hematuria or hydronephrosis identified on follow-up US, because it is noninvasive.
Conclusion
Although other ureteral reconstruction methods using the colon have been reported,
this would appear to be the first report in the English language of the TDC being
used to create a funnel-shaped segment to reconstruct a long upper ureteric stenosis
following two failed pyeloplasties. To date, no complications associated with colonic
mucus secretion have been reported. For pediatric surgeons who perform pyeloplasty,
this procedure may be a useful option if hydronephrosis recurs and a long upper ureteric
stenosis is seen.
