Since first described by Anderson and Hynes in 1949, open dismembered pyeloplasty remains the gold standard for PUJO treatment [11]. In more than 95% of cases, this technique is successful [12]. In spite of this very high success rate, the period over which satisfactory non-obstructive pattern of renal function is usually not predictable. In some cases, the initial postoperative radiological investigation shows no signs of successful surgical correction. This is extremely stressful situation for both surgeon and patients (or their parents); however, most of these cases show spontaneous improvement by time. Thus, finding predictor of the outcome course is urgently needed.
Histological changes in the renal pelvis in response to obstruction determine its compliance after pyeloplasty [1, 3]. Many studies—including our study—tried to correlate the outcome of the surgery with histopathological changes in the renal pelvis. Most of them focused on mRPSMT, collagen-to-smooth muscle ratio and elastin content of the renal pelvis.
In this study, our data showed a clear relationship between mRPSMT and the time over which radiological improvement occurs; increase in mRPSMT is associated with a delay in postoperative radiological improvement time. We found no relation between elastin content nor collagen-to-smooth muscle thickness and postoperative improvement course.
Issi and his colleagues studied the effect of histopathology of resected PUJ segment during pyeloplasty on the outcome of surgery; they found no difference in quantity collagen type 3, elastin content, fibrosis, nor Cajal cells between the two study groups; group of immediate postoperative improvement and group of delayed improvement, so they concluded that none of these factors has impact on the outcome of surgery; this is supported by our data regarding elastin content and collagen [10].
In a trail to compare histologically between normal PUJ and PUJO, Doğan et al. studied number of interstitial cells, nerves, presence of fibrosis and inflammation in normal PUJ and PUJO, and they found no difference in these items between the two groups, so they concluded that none of these factors has a role in pathogenesis of PUJO [14]; on the other hand, some authors investigate the relation between the presence of interstitial cells in the resected segment of PUJ during pyeloplasty and the postoperative outcome, and they found that there is no interstitial cells found in the segments resected from cases that had bad surgical outcome [15].
We found statistically significant difference in the mean mRPSMT between improved and non-improved patient at 3, 6 month postoperative; however, this difference was not significant at 12 month and this was supported by Han et al., Kaselas et al. However in their study, they found positive correlation between mRPSMT and delayed postoperative radiographic improvement [3, 9].
Some reports showed increase in elastin content and correlate with delaying in postoperative improvement; this could be due to decrease elasticity and compliance [12, 16]. Kim and his colleagues correlate between collagen-to-smooth muscle tissue matrix ratio in PUJO and the outcome of pyeloplasty; they observed that the lower the tissue matrix ratio, the better improvement of hydronephrosis postoperative [13], whereas we found no significant relation of elastin content nor collagen-to-smooth muscle ratio to postoperative recovery course.
Persistent obstruction associated with prolonged time interval should be a worrying sign for both the parents and the treating surgeon. We can finally conclude from our results that the information retrieved from the histopathological examination of the obstructed PUJ samples after a dismembered pyeloplasty has an important clinical implication to be considered and thus could be used as a prognostic factor. Patient’s postoperative course and expected timing of hydronephrosis improvement, based on the thickness of their renal pelvis smooth muscle, should take much attention by the surgeon during the patient’s postoperative recovery time and until the first postoperative radiographic examination. Taking the histopathological data into consideration could successfully help the surgeon to roughly estimate the expected time over which improvement occur.
The limitation of the study was relatively small number of patients.