Ureteric reconstruction: Ureterolysis, reimplant, strictures

Proximal ureter

The proximal ureter, radiologically, is defined to be the segment of the ureter between the renal pelvis and the superior border of the sacroiliac joint. Some texts include the ureteropelvic junction (UPJ) within the proximal ureter; however, for the purposes of this chapter, the proximal ureter and UPJ will be considered two distinct entities, and thus pyeloplasty will not be discussed here as it has been a well-established surgery for UPJ obstruction. The proximal ureteral blood supply arises medial-to-lateral, mostly from the main renal artery with some contribution from smaller branches directly off the aorta as well as the gonadal artery. Thus, when performing an endopyelotomy for proximal ureteral strictures, the incision should be made laterally to minimize ureteric ischemia.

The more proximal the ureter, the more robust the vascularity, as it is closer to the branches from the main renal artery. This is one of the reasons why pyeloplasty outcomes are excellent. However, following the proximal ureter down caudally, the arterial plexus overlying the ureter becomes more tenuous before it meets another arterial plexus originating from branches off the gonadal artery or directly off the aorta. In other words, there are watershed regions of the proximal ureter, which makes strictures in this location more difficult to manage. Surgical dissection of the proximal ureter must be precise with care to leave as much adventitia on the ureter as possible and to avoid lateralizing the ureter extensively. Following those surgical principles in the proximal ureter decreases the risk of ischemia to the ureteral repair and subsequently decreases the risk of stricture recurrence.

Mid-ureter

The mid-ureter, radiologically, is defined to be the segment of the ureter between the superior border of the sacroiliac joint and the inferior border of the sacroiliac joint, or more simply, the pelvic inlet. This segment obtains its vascularity from posterior to anterior originating off the common iliac artery.

Distal ureter

The distal ureter, radiologically, is defined to be the segment of the ureter between the pelvic inlet and the ureterovesical junction. Its blood supply comes from lateral-to-medial from branches off the internal iliac artery and larger internal iliac artery branches (e.g., superior vesical, uterine, inferior vesical, middle rectal, etc.). Despite these multiple plexuses, ureteral vascularity is still tenuous. Blood supply to the bladder will almost always be superior to that of the distal ureter; thus, when managing distal ureteral strictures, ureteroneocystostomy/ureteral reimplantation is the reconstructive technique of choice.

Ureteral identification and dissection

The retroperitoneum must be adequately visualized prior to identifying the ureter. In proximal- and mid-ureteral strictures, the colon should be reflected medially by incising the white line of Toldt in order to expose the retroperitoneum underneath. On right-sided procedures, the Kocher maneuver may need to be performed in order to medialize the duodenum in order to visualize the hilar strictures of the kidney, including the gonadal vessels, which does aid in the identification of the ureter. In distal-ureteral strictures, depending on the adhesions of the bowel to the pelvic sidewall, retraction of bowel medially may be enough to adequately visualize the shape and pulsation of the iliac vessels, which is a good landmark for where to start looking for the ureter, which crosses the iliac vessels at the bifurcation of the common iliac into the external and internal iliac vessels.

In certain cases where there may be strong fibrotic or desmoplastic reactions in the retroperitoneum, finding the ureter may be particularly challenging. A fibrotic rind may encase the ureter and distort the normal expected location of the ureter (e.g., RPF medializing the ureter). In these cases, it is advantageous to identify the normal ureter either proximal or distal to the diseased segment and to follow it from known to unknown, as a surgical principle.

Should anatomic considerations be inadequate in identifying the ureter, there are some adjunctive techniques that may help. If the patient already has an indwelling ureteral stent in place, an ultrasound probe may prove to be useful in identifying the stent; using the same logic, if a patient does not have a preexisting indwelling ureteral stent, an open-ended ureteral catheter may be placed intraoperatively in order to assist in ultrasonographic identification. Ureteroscopy is very helpful when performing ureteral reconstruction, as it allows for correlation between the intraluminal status of the ureter with the extraluminal appearance robotically. The latest robotic console software includes a near-infrared imaging (NIRF) modality. Ureteroscopy comes in handy with the utilization of NIRF, as the light emanating from the ureteroscope is enhanced in NIRF, allowing for identification of the ureter. One adjunct that has been increasingly popular is the use of intraureteral indocyanine green (ICG). Five mL of diluted ICG can be instilled either retrograde via cystoscopy with ureteral catheterization or antegrade via an existing nephrostomy tube. ICG binds to the tissues of the ureter and is fluorescent green in the NIRF setting. ICG has also been commonly used intravenously (2 mL) to assess for tissue perfusion ( Fig. 33.1 ). Thus, the downside to utilizing intraureteral ICG for ureteral identification is that the option to use it intravenously to assess for ureteral vascularity becomes confounded. Because of this, if the ureter can be identified without using intraureteral ICG, it may be advantageous to save the ICG to be used intravenously in order to ensure the reconstructed segment of ureter is adequately perfused.

After the ureter has been identified, it needs to be isolated. The anterior aspect of the retroperitoneum overlying the ureter should be incised into until the adventitia is visualized, with judicious electrocautery use to minimize ischemia. While the anterior ureter is generally safe to dissect out, a surgeon may choose to hedge toward one side or the other based on the diseased segment location; as mentioned previously, the proximal ureter obtains its arterial branches medially and thus dissecting anterolaterally may preserve more blood supply while the distal ureter obtains its arterial branches laterally and dissecting anteromedially may be beneficial in the pelvis. Usually, circumferential isolation of the ureter is performed, but depending on the etiology of stricture, it may not be needed. If there is concern that extraluminal tissue is contributing to the ureteral stricture (e.g., RPF), circumferential isolation should definitely be performed. If an omental wrap needs to be performed (e.g., buccal mucosal ureteroplasty, ureterolysis), getting completely around the ureter is needed. However, in circumstances where ureteral dissection is tough and may compromise the adventitia and its vascular plexus, and the surgeon is able to reconstruct the ureter without complete ureteral transection (e.g., appendiceal bypass or side-to-side reimplantation), circumferential isolation may not be needed.

Finally, one important aspect of ureteral identification and dissection is discerning healthy tissue versus unhealthy tissue. A reconstructive surgical principle is to trim or exclude unhealthy tissue until a viable ureter is seen so that an anastomosis will have optimal perfusion for healing. An unhealthy ureter is generally pale or discolored with minimal to no bleeding when cutting into it. If there is any question about the viability of tissues, 2 mL intravenous ICG, as mentioned above, is an excellent modality to assess for tissue perfusion.

Ureteral rest

An emerging concept that has been extrapolated from a universally accepted urethral reconstructive principle is ureteral rest. Defined as the absence from ureteral instrumentation for a prolonged period of time leading up to the operation, ureteral rest has been proven to be beneficial in ureteral reconstructive outcomes. A recent multi-institutional retrospective study of 234 patients showed that those who had no indwelling ureteral stent or percutaneous nephroureteral tube for at least 4 weeks prior to surgery had a 90.7% success rate versus 77.5% in those without ureteral rest ( P = .057), with fewer patients needing to undergo buccal mucosa graft ureteroplasty. The hypothesized physiology behind ureteral rest is tissue recovery and maturation of the stricture, as recent instrumentation and/or continued hardware (indwelling ureteral stent or nephroureteral tube) alters stricture characteristics with more periureteral inflammation, making surgery more technically difficult and tissue healing less effective.

Retroperitoneal fibrosis

Ureterolysis is a procedure reserved to manage patients who have ureteral obstruction secondary to extrinsic compression. Causes may include tumors, infection, and, most commonly, RPF. RPF is a process characterized by fibrosis and chronic retroperitoneal inflammation, usually originating from periaortic and other great vessels’ adventitia. RPF is a general term, with some of its causes including endovascular stents (for abdominal aortic aneurysms, for example), spinal hardware, prior retroperitoneal surgery, radiation, medication adverse effects especially that of ergot alkaloids (such as methysergide), and other processes that recruit inflammatory reactions affecting the retroperitoneum. Thus, RPF is not to be confused with idiopathic RPF, which, as its name suggests, is an inflammatory process unable to be attributed to as secondary to an inciting event. While rare, with an incidence of 0.1 to 1.3 cases/100,000 people annually, idiopathic RPF is thought to have an etiology from disease processes on the spectrum of autoimmune disorders such as large vessel vasculitides. Over the past decade, a relationship to IgG4 has been described, with its pathophysiology hypothesized to be a lymphoplasmacytic, fibrotic, and IgG4+ plasma cell infiltration of various organ systems. It is associated with other autoimmune disorders such as rheumatoid arthritis, ankylosing spondylitis, systemic lupus erythematosus, and, most commonly, thyroiditis.

The most common sequelae of RPF is ureteral involvement which can be bilateral or unilateral. At the time of diagnosis of unilateral disease, the contralateral side can be affected gradually between weeks to years, albeit rare. Multiple studies have shown that the risk of contralateral obstruction is low, and thus, bilateral ureterolysis for unilateral disease is not required. Classically, the mid to proximal ureter is affected, extrinsically compressed and deviated medially.

Prior to surgical intervention, the etiology of RPF should be determined. ^, If the secondary RPFs have been ruled out, and an idiopathic/autoimmune etiology is most likely, a trial of glucocorticoids and/or other immunosuppressive treatments with temporizing urinary drainage with indwelling ureteral stents or nephrostomy tubes have been studied. Medical treatment is particularly considered in mild to moderate obstruction. First-line medical treatment is prednisone with an initial dose of 0.75 to 1 mg/kg/day with a gradual taper to 5 to 7.5 mg/day within 6 to 9 months. Addition of immunosuppressive agents such as mycophenolate mofetil and cyclophosphamide may also be considered. Some studies have suggested that tissue diagnosis of the RPF should be performed in order to guide treatment. Some diseases such as lymphoma may mimic RPF. In the scenarios in which tissue diagnosis is warranted, surgical excisional biopsy should be performed concurrently with ureterolysis.

Patient positioning and trocar placement

For unilateral ureterolysis, the patient should be in semilateral decubitus (like that of a robotic nephrectomy) with modified low lithotomy, particularly for urethral access in female patients. All four arms of the da Vinci Xi system are used, in addition to one 5- or 10-mm bedside assistant trocar. All trocars except the most caudal one should be equidistant away from the vertical midline, approximately 2 to 3 cm on the ipsilateral side. The caudal-most trocar for retraction should be further medial right at midline. Seen in Fig. 33.2 .

For bilateral ureterolysis, the patient is positioned supine with low-modified lithotomy. The setup is almost identical to that of a robotic retroperitoneal lymph node dissection, except for the low modified lithotomy, with all ports along the Pfannenstiel line, as seen in Fig. 33.3 .

Technique

Ureteral identification and dissection have been discussed above. After the adventitia of the ureter has been identified, ureterolysis should be done in a systematic fashion by peeling back the anterior tissue, then exposing circumferentially to free the ureter from its posterior fibrosis. Using a vessel loop after the posterior has been freed is helpful to provide soft traction anteriorly to continue ureterolysis proximally and distally until normal periureteral fat is encountered. The fibrotic rind usually is not difficult to peel off the ureter once the correct plane has been established. Potts scissors for finer dissection may be helpful.

After the ureterolysis, a biopsy of the periureteral tissues and retroperitoneal mass should be sent off for pathologic evaluation. The ureter should then be assessed for its perfusion and can be done with intravenous ICG. If after ureterolysis, the tissue does not perfuse well, it may be necessary to excise the segment and perform ureteroureterostomy or other techniques, such as buccal graft ureteroplasty as described later in the chapter.

An omental wrap is then performed. A healthy omentum encasing the entire length of the ureter is used to prevent the recurrence of ureteral obstruction from its surrounding fibrotic tissues. The distal edge of the omentum is bifurcated. Enough should be mobilized to wrap the entire length of the ureter, and if more length is needed, the short gastric vessels can be ligated, freeing the omentum from the stomach. Care must be taken to preserve the left and right gastroepiploic arteries. If there is inadequate omentum, peritonealizing the ureter can be performed, although not preferred. The idea is to anteriorly displace the ureter and keep it out of the fibrotic retroperitoneum by tacking the peritoneal attachments of the colon underneath the ureter to the side wall. This technique does not provide the additional vascularity to the ureter as omental wraps do, and thus it is the opinion of the authors that it should be used as a last resort.