Ureteroscopic and scanning electron microscopical findings in ureteral anastomoses after segment resection.

In an experimental study on 8 canine ureters, end-to-end anastomoses were performed after segmental resection between 9 and 13 cm, using two different surgical techniques. After 3 months of observation the three-dimensional structure of the anastomosis and the surrounding areas was investigated by ureteroscopy and scanning electron microscopy. 3 types could be differentiated by the morphologic features of the ureteral lumen: normal width, segmental stricture, and circumferential stricture. The results offer a plausible explanation for the occasional discrepancy between histologic findings of relatively normal lumen width, and functional disorders apparently reflecting ureteral stenosis. They further support that excellent functional and morphologic reconstruction can be achieved even under the extreme conditions of 13 cm segmental resection with obligatory anastomosis under tension. The findings connected with dilatations observed distal to the anastomotic site appear rather contradictory, their interpretation is difficult.

[Clinical experience using polyurethane ureter endoprostheses and studies of the incrustation tendency]. / Klinische Erfahrungen mit Ureterendoprothesen aus Polyurethan und Untersuchungen zur Inkrustationstendenz.

The advantages of internal urinary drainage by using ureteral splints have often been discussed during the last years. Using this technique in our clinic for 17 years nearly 2000 ureteral splints have been applied in 650 patients. Since 1978, in 164 patients ureteral splints made of polyurethane (PUR) were used. The indications are listed. The complication-rate is very low. Ureteral splints which had been removed after varying periods were examined by scanning electron microscopy. Results of these studies are shown.

Scanning electron microscopy of urinary calculi--some peculiarities.

Within the scope of the investigation of more than 1,500 urinary calculi by scanning electron microscopy (SEM), some peculiarities arose concerning secondary phase transitions and morphology of some of the crystalline phases present. There is evidence for a phase transition from Ca-oxalate dihydrate to the monohydrate form in oxalate rich stones. This is characterized by a transitional zone, in which often relatively large monocrystals of newly formed whewellite are found, sticking within weddellite crystals with typical dissolution signs. We conclude that the phase transformation is regulated by dissolution and recrystallization. In mixed uric acid / uric acid dihydrate stones, occasionally parallel growth of apparently two different kinds of crystals upon each other can be observed, which possibly are uric acid crystals grown epitaxially on uric acid dihydrate. A few nearly pure whewellite stones with little Ca-phosphate at the central core show tubules which obviously had been part of a calcified renal papilla and so had been acting as a nidus for stone formation. Bacterial footprints as well as calcified bacteria have only been found in apatite containing stones of patients with urinary tract infections by Escherichia coli. These bacteria are likely responsible for the origin of these footprints.