Physiology of Lower Urinary Tract Obstruction

Tandem ureterocystoplasty

BACKGROUND

Bladder augmentation may be undertaken by using various gastrointestinal segments but their use is associated with a multitude of well-recognized complications. The mega-ureter has proven to be a satisfactory alternative; in patients with bilateral mega-ureters, both ureters may be used for this purpose.

METHODS

Seventeen patients had augmentation ureterocystoplasty, including three in whom both distal ureters were used in tandem. The latter included two patients with neurogenic bladder and one with bladder exstrophy.

RESULTS

Satisfactory augmentation was achieved in all patients undergoing tandem ureterocystoplasty. The neurogenic bladder patients are managed by urethral clean intermittent catheterization (CIC) and the exstrophy patient is managed by CIC of an appendicovesicostomy (Mitrofanoff). All are continent.

CONCLUSIONS

The mega-ureter provides an excellent source of augmentation material in patients with small non-compliant bladders. In those with bilateral mega-ureters, consideration should be given to using both ureters in tandem to achieve the maximum possible bladder capacity.

Electrovesicography in benign prostatic hyperplasia

The electric activity of the urinary bladder (UB) as demonstrated by electrovesicogram (EVG) was studied in 26 patients with benign prostatic hyperplasia (BPH) and in 10 healthy volunteers. Ten of the BPH patients were in the compensated stage and 16 were in the decompensated stage. Three electrodes were applied to the skin of the hypogastric area and one reference electrode was applied to the lower limb. Recordings were made from the full and empty UB and after the residual urine had been evacuated. In healthy volunteers, pacesetter potentials (PPs) were recorded as triphasic waves from the full and empty UB. Amplitudes were lower in the empty than in the full UB (p < .05), and were reproducible in the individual subject. The EVG of the compensated prostatic patients showed, in both the full and empty UB, PPs of higher frequency, amplitude, and velocity than that of the controls (p < .01 and p < .05, respectively), a condition called "tachyvesica." In the decompensated prostatic patients, the EVG showed a bradyarrhythmic pattern in the full UB and a silent pattern in the empty UB. It would appear that EVG recorded for BPH could be used to differentiate the compensated from the decompensated hyperplastic prostate. The technique is simple, easy, noninvasive, nonradiologic, and without complications when compared with other investigative methods.

Developmental alterations in the fetal lamb bladder subjected to partial urethral obstruction in utero

To identify the structural changes seen in the developing bladder subjected to outflow obstruction, a fetal lamb model was developed. With this model, which attempts to reproduce conditions such as those found in posterior urethral valves, quantitative biochemical parameters were used to evaluate the effects of partial outflow obstruction on detrusor cellularity and innervation in the developing bladder. Partial urethral obstruction was created in 9 fetal sheep (90 to 100 days gestation), 6 sham operated animals serving as controls. Fetuses were delivered at term and sacrificed. Bladders were removed and weighed. Mucosa free detrusor was assayed for DNA and choline acetyltransferase (ChAT) activity, indices of cell number and cholinergic innervation, respectively. In similar specimens of detrusor, cell ploidy and nuclear size were determined by flow cytometry and nuclear morphometry, respectively. The results showed that partial urethral obstruction in utero resulted in a significant increase in bladder weight (p < 0.05) and total detrusor DNA content (p < 0.01). With the increase in detrusor DNA content, there was a parallel increase in total detrusor ChAT activity. These results suggest that early development of the bladder is altered both on a cellular level (increase in cellularity) and a neural level (increase in cholinergic nerve density) under conditions of mechanical distension.