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Invited Commentary |
Department of Urology, Wake Forest University School of Medicine, Winston-Salem, North Carolina
Urologic surgeons are mainly interested in two things when a patient has a possible UPJ obstruction: (a) Is there a functional obstruction? (b) If so, what is the best treatment? The first issue is usually addressed with nuclear renography. Open surgical pyeloplasty was the main treatment used for years, but patients now have a number of minimally invasive options, including balloon dilation (30-F balloon), retrograde or antegrade endopyelotomy, retrograde incision with a cutting balloon device (Acucise; Applied Medical Resources, Laguna Hills, Calif), and laparoscopic pyeloplasty.
Open surgical pyeloplasty and laparoscopic pyeloplasty have the highest reported success rates (90%–96%), whereas the success rates of the other modalities are lower (60%–83%) (1–20). Although the results reported for laparoscopic pyeloplasty are excellent, this procedure is technically challenging and is being performed only at a few centers. The patient will usually select one of the other less invasive alternatives, which most urologists can perform.
The lower success rates of these procedures have prompted a search for factors that predict treatment failure. Van Cangh and associates (20) reported that the presence of crossing vessels at the UPJ is associated with a lower success rate for antegrade endopyelotomy: 42% in patients with crossing vessels and 86% in patients without crossing vessels. The patients in that study underwent digital angiography. Crossing vessels are present in approximately 50% of kidneys with UPJ obstruction (21). The vessels are not thought to be the cause of this problem, and their role in endopyelotomy failure has not yet been completely elucidated. Massive hydronephrosis has been shown to decrease the success rate of endopyelotomy. Van Cangh and colleagues (20) reported a 77% success rate in cases of mild hydronephrosis versus a 66% success rate in cases of moderate to severe hydronephrosis. Danuser and associates (5) confirmed this finding, reporting successful endopyelotomy results in 87% of patients with a collecting system volume of 50 mL or less versus 76% of patients with a larger collecting system volume. Gupta and colleagues (21) found that if the involved kidney has poor function (<25% of global function at scintigraphy), the success rate of endopyelotomy decreases. The success rate was 54% in such cases versus 80% in kidneys with 25%–40% of global function and 92% in kidneys with more than 40% of global function.
In the preceding article , Mitsumori and associates clearly demonstrate that helical CT is quite sensitive in identification of crossing vessels. Another attribute of this radiologic technique is that it allows quantification of collecting system volume. It is also less invasive than conventional angiography. Endoluminal ultrasonography has also been used to identify crossing vessels and can also help direct the endopyelotomy incision to avoid vascular injury, a potentially serious complication of the procedure (22–24).
The use of radiologic imaging to identify crossing vessels before endopyelotomy is not universally endorsed by practicing urologists. The added cost and the question of whether crossing vessels actually have a significant role in endopyelotomy failure are arguments against this approach. Gupta and colleagues (21) reported that only 13 (24%) of 54 patients in whom endopyelotomy was unsuccessful were found to have crossing vessels at open surgical exploration. Extrinsic and intrinsic fibrosis at the area of incision was the most prevalent finding. In addition, anatomic studies have demonstrated that a laterally directed incision through the UPJ will avoid vascular structures in most cases (25,26). A number of urologists will just cut laterally in their patients without obtaining anatomic radiologic confirmation of this route. They consider performing radiologic studies only in cases of secondary UPJ obstruction, in which vascular relationships can be distorted, or in cases of ectopic kidneys, in which the anatomy is not always predictable.
References
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