1. The effects of altering extracellular pH on the electrically evoked contractions of ferret and human bladder (detrusor) smooth muscle have been investigated. pH was varied by changing superfusate PCO2 or NaHCO3 concentration. Acidosis increased force when superfusate PCO2 was raised but decreased force when the NaHCO3 concentration was reduced. 2. Intracellular pH (pHi) in isolated ferret detrusor cells was measured separately by epifluorescence microscopy. Extracellular pH changes caused by altering superfusate PCO2 were accompanied by similar changes of pHi, whereas variation of the NaHCO3 concentration had smaller effects on pHi. 3. It was proposed that intracellular acidosis increased contraction but extracellular acidosis depressed contraction. 4. Other interventions, such as addition and removal of NH4Cl, Cl- replacement, and NaHCO3 replacement with HEPES, changed pHi and had predictable effects on force. It was possible to describe unique relationships between tension and either intracellular or extracellular pH regardless of the means whereby pH changes were brought about. 5. Resting tension was reduced whether brought about by either intracellular or extracellular acidosis. K+ contractures were similarly affected by acidosis. Ferret preparations showed low levels of spontaneous activity, which was reduced by acidosis and enhanced by alkalosis.

SUMMARYAn 86-year-old woman underwent routine catheter replacement in the community. The new catheter failed to drain urine. Attempts to remove the catheter failed, both by the community nurse as well as by the urology team in the hospital. A CT scan confirmed that the catheter balloon was inflated in the distal right ureter. The patient was started on antibiotics and listed for cystoscopy under general anaesthetic. The catheter was visualised entering the right ureter and the balloon punctured using a wire under image intensifier guidance. Once removed, a new catheter was inserted. Very dilated ureteric orifices were noted. Post operatively the patient required HDU support for 48 h due to sepsis and on recovery was discharged home. The key learning point in this case is to always consider catheter misplacement in the ureter if it is not draining well and the patient presents with pain.

The first blind, prospective, randomised comparison of flexible cystoscopy with rod-lens cystoscopy was carried out on 53 consecutive volunteers with bladder tumours or haematuria. Three patients' recurrences were missed on flexible cystoscopy and 3 others on rod-lens examination. It was expected that the 9% rate of missed tumours would lessen with increased experience of flexible cystoscopy, as 2 of them occurred in the first 12 examinations and all of the lesions missed were < 5 mm in diameter. Rod-lens cystoscopy, the accuracy of which appears to have been measured for the first time, was no more sensitive.

Our initial experience of extracorporeal shock wave lithotripsy (ESWL) with the Storz Modulith SL20 is reported. A total of 500 patients with 551 renal and 120 ureteric stones, mean diameter 11.9 mm, underwent 746 treatments; 68.2% of patients required a single treatment. The mean treatment rate for renal calculi was 1.4 and for ureteric calculi it was 1.5, rising to 4.2 for staghorns; 62.2% of treatments were performed on an out-patient basis. Analgesia (intravenous fentanyl) was required in 60.9% of treatments for renal calculi but in only 38.2% of those for ureteric calculi. The overall stone-free rate at 3 months was 77.6%, with a further 14.7% of patients having fragments less than 3 mm in diameter that required no further treatment. The stone-free rate was dependent on the site of the stone, with the majority of residual fragments lying in a lower pole calix. There were few complications. The Modulith is an efficient and safe lithotripter capable of treating stones in the kidney and throughout the ureter.