The Probot--an active robot for prostate resection.

As men age, their prostates can enlarge, causing urinary difficulty. Surgery to correct this [transurethral resection of the prostate (TURP)] is a skilled and time-consuming operation requiring many repetitive motions of a cutter. A robot has been developed to perform these motions, relieving the surgeon of much of the burden of surgery. This robot has been tried both in the laboratory and later on human subjects and has proved itself capable of performing prostate resection. The Probot system consists of on-line imaging and three-dimensional prostate model construction, an appropriate surgeon-computer interface, a counterbalanced mounting frame and a computer controlled robot.

Comparison of prostatic volume and dimensions by transrectal and transurethral ultrasonography.

OBJECTIVE: To compare the volumes and dimensions of the prostate gland as measured by transrectal and transurethral ultrasonography (TRUS and TUUS) and to study the prostatic changes that occur in the presence of an urethral instrument. PATIENTS AND METHODS: Twenty men (mean age 71 years, range 43-85) with symptoms of prostatic enlargement underwent TRUS and the dimensions and volumes of their prostates were obtained by the dimensional method and by step planimetry. Within 24 h, all the men were examined cystoscopically under sedoanalgesia and underwent TUUS. Their prostatic volumes and dimensions were again measured by the dimensional method and by step planimetry. Step planimetry was carried out using a specially designed indexer firmly attached to the examination couch or operating table. All the static images and planimetry slices were video recorded for later computer enhancement and to study the three-dimensional changes occurring in the prostate. The volumes and dimensions obtained by TRUS and TUUS were compared. RESULTS: Volumes obtained by transurethral step planimetry were 22% greater than those from transrectal planimetry. Although there was a good correlation (r = 0.984) between transurethral planimetry and the volumes derived using the transurethral dimensions with the prolate ellipsoid formula, the latter produced values 17% and 25% lower by the transurethral and transrectal routes, respectively. These volume estimates varied widely, indicating that the simple addition of a constant to the prolate ellipsoid formula would not correct the volume. Three-dimensional changes of the prostate occurred with TRUS and TUUS: with TUUS, the craniocaudal and anteroposterior diameters were significantly larger (by 7% and 18%, respectively) while the transverse diameter was smaller by 20%. CONCLUSION: The estimated volumes and dimensions of the prostate differed when measured by TRUS and TUUS and three-dimensional changes in the prostate occurred in the presence of an urethral instrument.

Transrectal ultrasonography: why are estimates of prostate volume and dimension so inaccurate?

OBJECTIVES: To determine why there are variations in the volumes of the prostate obtained by step planimetry and those calculated from the prolate ellipsoid formula using the measured maximum gland dimensions, to assess the reproducibility of estimates of prostate volume from transrectal ultrasonography (TRUS) and to determine the effect of the angle of the transrectal probe, the human error in the clinical setting and the benefit of computer enhancement of the ultrasonograms. PATIENTS AND METHODS: Forty-five men (mean age 72 years, range 43-89) with symptoms of prostatic enlargement were divided randomly into three groups; those in group 1 had their prostate volume estimated three times by measuring the maximal gland dimensions and calculating the volume using the prolate ellipsoid formula (dimensional method) and by step planimetry, to assess the reproducibility of TRUS; men in group 2 had their prostate volume estimated using the dimensional method and by step planimetry with the probe in the optimal axis, and then from scans repeated after deflecting the transrectal probe 5 degrees anteriorly and posteriorly; men in group 3 had their prostate volume estimated once by the dimensional method and by step planimetry. Step planimetry was carried out using a specially designed indexer firmly attached to the examination couch. All 'frozen' images and planimetry slices were videotaped for later computer enhancement. The volumes and dimensions obtained by each method were compared. RESULTS: The volumes obtained by step planimetry were 17% greater than those obtained by the dimensional method because the craniocaudal, anteroposterior and transverse diameters were underestimated significantly by the latter (by 13%, 2% and 7%, respectively). The largest anteroposterior and transverse diameters were included in the same axial scan in only 44%, while the largest craniocaudal diameter was in the midline in only 38%, of the patients. The human error in the clinic was negligible (2%) with a good correlation between the dimensions and volumes obtained in the clinic and those from computer-enhanced images (r = 0.94). There were no advantages in computer enhancing the TRUS images. Volumes calculated from the dimensional method using the maximum dimensions obtained from planimetric contours correlated well with planimetric volumes (r = 0.93). The reproducibility of TRUS showed a mean error of 8% by the dimensional method and 1% by step planimetry. Anterior deflection of the transrectal probe reduced the estimated volume by 2% and posterior deflection increased the volume by 4%, using the dimensional method, while there were no significant volume changes when estimated by step planimetry. CONCLUSION: This study confirms that to estimate accurately the volume of the prostate using the prolate ellipsoid formula, the current methodology needs to be changed. The largest anteroposterior and transverse diameters may need to be measured in different transverse scan slices and the largest craniocaudal diameter in a sagittal scan away from the midline. If volume estimation is to be repeated then step planimetry is reliable and TRUS using the prolate ellipsoid formula is not.

Minimally invasive surgery. Future developments.

The rapid development of minimally invasive surgery means that there will be fundamental changes in interventional treatment. Technological advances will allow new minimally invasive procedures to be developed. Application of robotics will allow some procedures to be done automatically, and coupling of slave robotic instruments with virtual reality images will allow surgeons to perform operations by remote control. Miniature motors and instruments designed by microengineering could be introduced into body cavities to perform operations that are currently impossible. New materials will allow changes in instrument construction, such as use of memory metals to make heat activated scissors or forceps. With the reduced trauma associated with minimally invasive surgery, fewer operations will require long hospital stays. Traditional surgical wards will become largely redundant, and hospitals will need to cope with increased through-put of patients. Operating theatres will have to be equipped with complex high technology equipment, and hospital staff will need to be trained to manage it. Conventional nursing care will be carried out more in the community. Many traditional specialties will be merged, and surgical training will need fundamental revision to ensure that surgeons are competent to carry out the new procedures.

Treatment of urinary tract stones.

Replacement of open surgery with minimally invasive techniques for treating stones in the renal tract has greatly reduced patients' morbidity and mortality and the period of hospitalisation and convalescence. Extracorporeal shockwave lithotripsy does not require anaesthesia and requires little analgesia so that treatment can be given on an outpatient basis, and there is no wound to heal. Only a small puncture site is needed for percutaneous endoscopic lithotomy, and with the advent of prophylactic antibiotics there are few complications. Of renal stones, about 85% can now be successfully treated by extracorporeal lithotripsy alone, and almost all of the stones too large or hard for lithotripsy can be treated endoscopically, with ultrasonic or electrohydraulic probes being used to fragment the stone. Stones in the upper and lower thirds of the ureter can be treated by extracorporeal lithotripsy, but stones in the middle third, which cannot normally be visualised to allow focusing of the shockwaves, usually require ureteroscopy. Nearly all bladder stones can be treated by transurethral endoscopy with an electrohydraulic probe. Only the largest renal tract stones still require open surgery.

Chemical analysis of post-lithotripsy stone fragments: a critical evaluation.

A scheme for the chemical microanalysis of renal stone fragments recovered from urine voided immediately after lithotripsy has been developed and evaluated. The analytical procedure includes assay of calcium, magnesium, phosphate, oxalate and urate and has been applied to 78 such urine samples. Problems relating to co-existing crystalluria and blood and urine contaminants have been recognised and overcome. However, significant loss of all stone components due to fragment dissolution in urine prior to recovery was found to occur and was investigated. The distribution of stone components found in these analyses was similar to that seen in previous surveys of intact stones.

Developments in the ureteroscopes, techniques and accessories associated with laser lithotripsy.

Two stages in the development of the technique of laser lithotripsy are described. In the first series, spanning 1985-1988, three consecutive groups of patients are compared. In the first 100 patients, 11.5-F ureteroscopes were used. Access on first retrograde attempt was successful in 73%; 3% developed strictures; the ureteric perforation rate was 7%; and 12% required nephrostomy drainage. These results contrast with those of the third group in this series, consisting of 200 patients using a miniaturised ureteroscope. Access on the first retrograde attempt was successful in 99%. There were no strictures, no perforations and no requirements for nephrostomy drainage. (The second group of 100 patients using a range of rigid ureteroscopes was intermediate in its complication rate: 2% developed strictures, the ureteric perforation rate was 3%, and 6% required nephrostomy drainage). In the second series, spanning 1989-1990, the procedures were performed by all grades of urologists using miniaturised endoscopes. An in-depth audit was performed and each patient was followed until completely clear of fragments. The stones were successfully accessed on the first attempt in 213 cases (89%). In group A (139 patients, no basket used) 32 renal units (23%) were cleared of stone fragments immediately following the procedure, rising to 78 units (56%) by 3 months and 99 units (71%) beyond 3 months follow-up. Some fragments remained in 40 renal units and were cleared by further ureteroscopy, ESWL or PCNL, with the exception of 1 patient who had small residual fragments despite ESWL for fragments flushed to the kidney.(ABSTRACT TRUNCATED AT 250 WORDS)

An introduction to minimally invasive therapy.

Minimally invasive therapy (MIT) has as its basic premise the reduction of iatrogenic trauma to the patient by surgeon, physician or radiologist. This approach must also imply that the therapeutic procedure succeeds in its aim of cure in a manner no less effective than is currently achievable by established methods of treatment. Acceptance of this principal has many identifiable sequelae, including profound changes in hospital design, increasingly expensive technological instrumentation, more sophisticated teaching and learning patterns, and a massive redirection of health care financial resources. These changes cannot be contemplated at leisure, because they are dynamically imperative and progressing with relentless rapidity, being directly driven by the consumer. It is vital that this shift in clinical emphasis should be appreciated so that future planning can be undertaken with some rationality.

Effect of oral erythromycin on gallbladder motility in normal subjects and subjects with gallstones.

The action of the motilin receptor agonist erythromycin on human gallbladder contraction, measured by ultrasound, both in normal subjects and those with gallstone disease was studied. In 17 normal subjects, oral erythromycin administration (500 mg; vs. placebo) reduced fasting gallbladder volume at 2 hours (26.2 vs. 19.0 mL; P less than 0.001), and postprandial residual gallbladder volume (9.0 vs. 4.4 mL; P less than 0.001) and the rate constant of gallbladder emptying following the meal was significantly increased. Erythromycin also reduced fasting and residual gallbladder volumes in 13 patients with gallstone disease: in 6 who underwent cholecystolithotomy, fasting volume was 29.5 vs. 22.3 mL (P less than 0.05) and residual volume was 17.7 vs. 6.5 mL (P less than 0.05), and in 7 with gallstones in situ, fasting volume was 23.8 vs. 14.3 mL (P less than 0.05) and residual volume was 17.2 vs. 5.0 mL (P less than 0.05). In 7 of 8 subjects with gallstones and impaired gallbladder emptying, the gallbladder emptied normally following administration of erythromycin, and in 3 of the other 5 gallstone subjects gallbladder emptying was increased. In 6 normal subjects given erythromycin three times weekly for 1 month, the effect was maintained (fasting volume, 18.8 mL, P less than 0.001; residual volume, 3.7 mL, P less than 0.001). Oral erythromycin significantly reduces fasting and postprandial residual gallbladder volumes in both normal subjects and subjects with gallstones and reverses the gallbladder motility defect found in a proportion of subjects with gallstones. This effect is maintained for a month in normal subjects.

Indomethacin and postprandial gallbladder emptying.

Patients with gallstone disease commonly have impaired gallbladder emptying. To see whether non-steroidal anti-inflammatory drugs (NSAIDs) prevent gallstone formation by improving gallbladder emptying, we assessed the effect of indomethacin on postprandial emptying in healthy subjects and in patients with gallstone disease. Subjects received indomethacin 25 mg three times a day for a week and matching placebo for another week. Compared with placebo, indomethacin improved postprandial gallbladder emptying in all 7 patients with gallstone disease. This finding was not recorded in healthy subjects with normal gallbladders. The prevention of gallstone formation associated with ingestion of NSAIDs may be due mainly to a prokinetic effect on the gallbladder since there is no evidence to suggest that these drugs affect cholesterol crystal nucleation at ordinary therapeutic doses in man or animals.

Extrusion of calculi from upper urinary tract into perinephric and periureteric tissues during endourologic stone surgery.

We report on 11 patients in whom fragments of calculi were extruded into the perinephric or periureteric tissues at the time of endourologic stone surgery. All patients have been managed conservatively. In 2 patients ureteric strictures developed, but these were probably secondary to an electrical injury as a result of electrohydraulic lithopaxy. The remaining 9 patients have not experienced serious sequelae as a result of the calculus extrusion.

A user's guide to flexible cystoscopes.

This survey, carried out on behalf of the BAUS Instruments Committee, aims to assist the urologist in choosing a flexible cystoscope. The 5 most commonly available flexible cystoscopes (from ACMI, Olympus, Pentax, Storz and Wolf) were assessed in a clinical setting for handling, image quality and user satisfaction. Several technical characteristics, including deflection range, irrigant flow rate and optics, were tested in the laboratory. Whilst all instruments were satisfactory, the favourite of our testing panel was the Olympus CYF-2, which also came out best in the technical assessment and has the most comprehensive service support. The cheaper Storz instrument also performed well.

[Development of an instrument for endoscopic liquefaction of the prostate]. / Desarrollo de un instrumento para la licuefacción endoscópica de la próstata.

Although the concept of prostate liquefaction had been proposed by Wickham 15 years ago, its clinical application has been delayed by various technical problems. The authors report on the investigative procedures that have been undertaken to design and develop the ELSA (Endoscopic Liquidiser and Surgical Aspirator) prototype which has been utilized in the clinical setting with promising results.

Percutaneous nephrolithotomy and the solitary kidney.

We reviewed 53 patients with stones in a solitary kidney who had undergone percutaneous nephrolithotomy. Previous surgery on that kidney had been performed in 35.8%, and 50.9% had other medical conditions including 26.4% who had impaired renal function. Staghorn or partial staghorn calculi were present in 52.9% and an additional 18.8% had multiple stones. Postoperative complications in 18.8% of the patients included sepsis, the need for transfusion and 1 death of bronchopneumonia. Percutaneous nephrolithotomy alone resulted in a 77.3% rate free of stone or fragments of 2 mm, or less. This rate increased to 86.8% with the addition of extracorporeal shock wave lithotripsy, ureteroscopy or open surgery (2 patients). Only 1 patient suffered long-term deterioration in renal function. Percutaneous nephrolithotomy is a safe procedure in the solitary kidney. It should be considered in those patients with complex stone burdens and impaired renal function when reduction in stone bulk and improved renal function may allow other treatment modalities to be used.

Percutaneous nephrolithotomy for calculi in horseshoe kidneys.

Between 1983 and 1988, 15 patients (18 kidneys) underwent percutaneous nephrolithotomy at this unit for calculi in horseshoe kidneys. A standard 1-stage percutaneous access technique with minor modifications was used. In situ disintegration with ultrasound or electrohydraulic lithotripsy was necessary in 15 moieties (83.3%) and nephrostomy drainage was required in 12 (66.7%). Percutaneous access was not a problem and there were minimal perioperative problems. Blood transfusion was required postoperatively in 2 patients. A total of 14 kidneys (77.8%) were rendered free of stone with percutaneous nephrolithotomy alone and 2 kidneys were left with asymptomatic stone fragments of 2 mm. or less. Another 2 kidneys became free of stone after extracorporeal shock wave lithotripsy, thus giving an over-all stone clearance rate of 88.8%. We conclude that percutaneous nephrolithotomy is an acceptable treatment for stones in horseshoe kidneys and it is the treatment of choice for patients in whom imaging is difficult or impossible.

The development of a surgeon robot for prostatectomies.

The removal of prostatic tissue through transurethral resection of the prostate (TURP) is an operation that can require considerable skill from a surgeon as well as being a lengthy procedure. The potential for using robotic techniques was investigated in a preliminary feasibility study using a standard six axis 'Puma' robot. This led to the construction of a manually operated 'safety frame' which has been shown to be effective through clinical trials on 30 patients. A special-purpose robot, based on the design of the manual frame, has now been constructed. Some of the safety issues are discussed which make this procedure an ideal candidate for a robotic device.