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M L Stoller

Publications and source records attributed to M L Stoller.

At least 91 records · Page 5Linked to original sources
PubMed1994

Clinical correlates of the gross, radiographic, and histologic features of urinary matrix calculi.

We present five patients with urinary matrix calculi, which, in contrast to the normally brittle calcigerous calculi, are soft, pliable, and amorphous. Common clinical features include a history of calcigerous stone disease, renal surgery, urinary obstruction or stasis, and chronic infection with Proteus species or coliforms. The diagnosis is usually made at surgery, but certain preoperative radiographic findings may be suggestive. Matrix calculi are radiolucent on plain abdominal films, although their appearance on nonenhanced CT scans is similar to that of calcigerous calculi despite their small mineral content. Extracorporeal shockwave lithotripsy is ineffective; open or percutaneous techniques are necessary. Histologic inspection reveals laminar concentric rings of organized matrix with an orderly, layered deposition of minerals. Histochemical investigation can provide insight into the possible sequence of events in normal calculogenesis. The successful management of urinary matrix calculi depends on a high index of suspicion and a thorough knowledge of their clinicopathologic features.

Adult↗
PubMed1994

Gas embolism: helium is more lethal than carbon dioxide.

The search for alternatives to carbon dioxide (CO2) for insufflation during laparoscopy has included the consideration of helium. Helium is attractive because it is noncombustible and has no pharmacologic effects. Unfortunately, it is also relatively insoluble in blood, which potentially could exacerbate a venous gas embolism. We performed rapid intravenous injections of CO2 and helium into 4 dogs in amounts ranging from 5 to 10 ml of gas per kilogram body weight. Recovery after CO2 injection always occurred within 1 min. In 4 of 6 instances, the helium injection was fatal. Our results confirm that helium is more lethal than CO2 when injected intravenously. This implies that the use of helium for insufflation during laparoscopy might place patients at greater risk for adverse effects should venous gas embolism occur.

Animals↗
PubMed1994

Ureteric retrieval net: comparison with stone extraction by Dormia baskets in an in vitro porcine model.

OBJECTIVE: To develop a ureteric retrieval net with advantages over existing stone retrieval methods. MATERIALS AND METHODS: In vitro experimental trials comparing the ureteric retrieval net with Dormia baskets were performed with porcine ureters and artificial calculi placed in a proximal or distal position. RESULTS: For removing a single, large stone (9 x 6 x 5 mm) the net was slightly better than baskets (100% versus 90%) and it was significantly (P < 0.001) more effective for removing multiple small stones (2 x 2 x 3 mm to 5 x 4 x 3 mm) in one pass (76% versus 40% with three distal stones; 73% versus 13% with three proximal stones; and 53% versus 3% with six proximal stones). CONCLUSION: This newly developed ureteric retrieval net has a compact design, resulting in minimal resistance during retraction. Its smooth hydrophilic outer surface enhances scooping properties against the luminal wall. The mesh is similar to that in nylon stockings--porous enough to allow flow, yet small enough to capture fragments. It can capture numerous small fragments with one scoop, but can easily disengage them if extraction is not possible. The loop encompasses the entire lumen with the 'pusher' offset to a side wall, allowing maximal space and visualization, and the device can dilate the ureter to facilitate extraction. Clinical studies are in progress to evaluate the full potential of this new device.

Animals↗
PubMed1993

Stimulated pressure response of the ileocolonic junctional zone and its use as a continence mechanism in a canine model.

Mechanisms for maintaining passive continence in the efferent limb of urinary diversions include compression of tissue, peristalsis, equilibration of pressure and use of valves. Motor activity and pressure in the ileum, ileocecal valve (ICV) and the colon were evaluated in dogs. Spontaneous activity and pressure were compared with stimulated pressure response and activity. Stimulation was performed at the pelvic nerve and the small nerves in the mesenterium, as well as direct neurostimulation of the bowel. Resting pressure at the ICV was 12.7 +/- 0.4 cmH2O rising to 26.4 +/- 2.2 cmH2O during spontaneous depolarization. Stimulation of the pelvic nerve resulted in increased colonic motor activity with unchanged pressure. Electric stimulation of small mesenterical nerves to the ICV increased pressure in the ICV to 35.0 +/- 4.1 cmH2O, while direct myoelectric stimulation of the ICV zone increased the intraluminal pressure to 75.0 +/- 3.2 cmH2O. Termination of the electric stimulation was followed by a slow decrease of pressure to the resting level over a period of 30-45 s. Maintaining continence at the ICV with long-term constant or intermittent stimulation seems feasible.

Animals↗
PubMed1993

Selection of patients for laparoscopic pelvic lymphadenectomy prior to radical prostatectomy: a decision analysis.

Indications for laparoscopic pelvic lymphadenectomy prior to radical prostatectomy have not been established. Criteria to predict lymph node metastases were derived from the preoperative evaluations of 164 prostate cancer patients undergoing pelvic lymphadenectomy. Decision analysis was used to determine which criteria would be optimal indicators for laparoscopic pelvic lymphadenectomy prior to intended radical prostatectomy. Besides a digital rectal examination suggesting uncontained tumor, which was the best indication for laparoscopic pelvic lymphadenectomy, the most useful criteria were sonographic tumor volume > or = 3 cc and prostate-specific antigen (PSA) > or = 20 ng/mL. If either parameter was met, the sensitivity for identifying patients with pelvic lymph node metastases was 88 percent and the positive predictive value was 42 percent. When both were met, the sensitivity fell to 47 percent but the positive predictive value increased to 67 percent. A combination of Gleason biopsy score and PSA was the best criterion that was independent of transrectal ultrasonography. Using a PSA > or = 15 ng/mL for tumors with Gleason biopsy score > or = 7 or a PSA > or = 25 ng/mL for tumors with a Gleason biopsy score of 5-6 had a sensitivity of 71 percent and positive predictive value of 48 percent for identifying patients with pelvic lymph node metastases. In selecting patients for laparoscopic pelvic lymphadenectomy prior to radical retropubic prostatectomy, criteria with a positive predictive value greater than 39 percent maximize the utility of laparoscopic pelvic lymphadenectomy. Prior to radical perineal prostatectomy, laparoscopic pelvic lymphadenectomy will identify pelvic lymph node metastases that would otherwise be undetected by prostatectomy alone. The sensitivity of selection criteria, therefore, should be increased, as long as the positive predictive value remains above 20 percent.

Aged↗
PubMed1993

Long-term follow-up of ventriculoureteral shunts for treatment of hydrocephalus.

Surgical relief of hydrocephalus is achieved mainly with ventriculoperitoneal or ventriculoatrial shunting. In some patients, frequent reoperations are required because of infection, obstruction, or other complications, thus subjecting them to excessive operative morbidity and risk of neurological damage. One option that has been rarely addressed in recent years is drainage of cerebral spinal fluid into the urinary tract by way of a ventriculoureteral shunt. Patients who have endured multiple revisions of standard cerebral spinal fluid shunts may benefit from a relatively lower frequency of reoperation following ventriculoureteral shunting. There are several complications peculiar to this procedure, however, including ascending infection from the bladder, proximal shunt migration out of the ureter or distal migration into the bladder, failed urinary diversion, and electrolyte disturbances associated with volume depletion. Long-term follow-up of patients with ventriculoureteral shunts has not been reported. We describe the course of 4 patients successfully treated with ventriculoureteral shunts for an average of more than five years per patient. Although all eventually required reoperation, the frequency of reoperation with the ventriculoureteral shunts was markedly lower than with the standard shunts in these patients. Ventriculoureteral shunting should be considered for cerebral spinal fluid drainage in selected patients with multiple failures of standard shunts, provided the bladder is a low pressure reservoir with no urine infection.

Adolescent↗
PubMed1993

The fate of the iatrogenic retroperitoneal stone.

Ureteral perforation with resultant retroperitoneal stone expulsion is a recognized complication of ureteroscopy. In a 5-year retrospective review of 400 cases we identified a 1.3% incidence of iatrogenic retroperitoneal stone dislodgment. Average followup was 21 months. Four cases were managed with observation and 1 required surgical correction of a ureteropelvic junction stricture. We discuss the management of this problem, which begins with thorough radiographic documentation in the perioperative period. Aggressive ureteroscopic manipulation and attempted stone retrieval are not warranted, and a ureteral stent should be placed. Radiographic followup and clinical observation confirm the low morbidity associated with retroperitoneal urinary stones. Patient understanding of the extra-ureteral stone location is essential to avoid misdiagnosis and mismanagement by uninformed physicians in the future.

Endoscopy↗
PubMed1993

Laparoscopic marsupialization of a simple renal cyst.

An 8 cm. symptomatic simple renal cyst, recurrent despite previous aspiration and injection of sclerosing agents, was marsupialized using laparoscopic techniques. No complications occurred and followup by ultrasonography confirmed resolution of the lesion. We suggest that laparoscopic management of symptomatic simple renal cysts may be an attractive alternative to open surgical techniques.

Aged↗
PubMed1993

Percutaneous suprapubic cystostomy.

Suprapubic urinary diversion for the management of lesions of the bladder outlet or urethra has been facilitated by the advent of percutaneous access techniques. Prior to percutaneous endourologic techniques, an open surgical approach was necessary when the transurethral route was impassable. A variety of percutaneous suprapubic cystostomy techniques have evolved in recent years. These have been based on several different access principles and offer the urologist a number of options. Selection of an individual technique is usually a matter of preference and familiarity with a particular manufacturer's product. The list of indications for such an approach is diverse and continues to expand.

Cystostomy↗
PubMed1993

Helically ridged ureteric stent facilitates the passage of stone fragments in an experimental porcine model.

We have developed a ureteric stent with features designed to facilitate active expulsion of ureteric stone fragments. Its unique characteristics include a helix-like ridge along a thin central core; the superior edge of the ridge is bevelled caudally and the inferior is concave. The ridge's outer edge is smooth and hydrophilic. As the stent is moved in relation to the ureteric wall (owing to respiratory motion and/or peristalsis), stone fragments will slip over the superior edge of the helical ridge. Once past this edge, they cannot migrate in a cephalad direction; they will pass down the helical trough or be ratcheted by the repetitive bevel and emerge through the ureteric orifice. To evaluate the effectiveness of the design it was compared with a conventional, smooth-surfaced double-pigtail stent in an ex vivo porcine model. A single artificial stone fragment (3 x 2 x 2 mm, 4 x 3 x 2 or 5.5 x 3 x 2 mm) was placed in the proximal ureter and the stent was moved up and down (56 studies with each type of stent). The helically ridged stent required a mean of 79 excursions (standard deviation 60, range 8-291). In contrast, the conventional stent was unable to move any stone fragments--even after more than 1000 excursions.

Animals↗
PubMed1993

Natural history and current concepts for the treatment of small ureteral calculi.

Six studies providing information on 2,704 patients were included into a retrospective analysis. The incidence of spontaneous passage relating both stone size and location was determined from these collated studies. The rate of spontaneous passage for stones smaller than 4 mm was 38% compared to 1.2% for those larger than 6 mm, irrespective of their position in the ureter at the time of presentation. Calculi discovered in the distal third of the ureter had a spontaneous passage rate of 45%, compared with the mid third of 22%, and the proximal third of 12%. Two thirds of all stones which passed did so within 4 weeks after the onset of symptoms. These data from the literature were compared to the treatment modalities applied for the last 100 consecutive patients treated with the diagnosis of ureteral stone at UCSF. 42% of the stones were found in the proximal, 13% in the mid and 45% in the distal third of the ureter. Treatment modalities included ureteroscopic stone extraction (36), ESWL (31) and watchful waiting for stone passage (30). Oral litholysis was performed in 2 cases and percutaneous removal of a proximal stone in 1. No calculus larger than 6 mm passed spontaneously. The passage rate from the proximal ureter was 18%, from the mid ureter 15%, and 38% from the distal ureter disregarding the size of the stones. The rate of complications reached 20% when symptoms exceeded 4 weeks in duration compared to 7% in patients with symptoms lasting less than 4 weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

The double-J ureteral stent: in vivo and in vitro flow studies.

Although most ureters can now be stented, the rate of ureteral obstruction from extrinsic compression remains relatively high. To illuminate the mechanisms of obstruction in these patients we performed 20 in vivo pressure-flow investigations in 14 patients with indwelling ureteral Double-J stents. All patients had a percutaneous nephrostomy tube in place. Our investigations revealed proper drainage to the bladder in 17 of the 20 studies at an average renal pelvic pressure of 19.9 cm. water. Vesicorenal reflux was noted at an average bladder pressure of 20 cm. water in 17 studies. Three stents appeared to be obstructed. They showed no drainage to the bladder but also no reflux. To evaluate the in vivo results we then performed an in vitro study of pressure-flow characteristics under conditions simulating ureteral obstruction. At physiological flow rates different ureteral stents showed no major differences in pressure-flow characteristics. With compression and kinking, flow resistance in softer stents was notably greater than in hard stents. Therefore, we believe that in patients with suspected extrinsic compression of the ureter hard Double-J stents should be used. Vesicorenal reflux appears to be a reliable predictor of stent function.

Aged↗
PubMed1992

Endoscopic and open stone surgery in morbidly obese patients.

Management of urinary stone disease in the morbidly obese patient can be troublesome and problematic. We present 4 recent female patients with an average weight of 442 pounds and an average height of 5 feet 2 inches. The patients underwent a total of 8 open surgical or endoscopic procedures for partial or complete staghorn calculi. Complications encountered included inability to reach the stones with rigid or flexible ureteroscopes, inadvertent incision above the 10th rib for pyelolithotomy, intraoperative rhabdomyolysis during a flank incision, consecutive temporary renal failure and wound infection. We discuss the limitations of extracorporeal shock wave lithotripsy, retrograde endoscopic manipulation, percutaneous antegrade surgery and open surgical approaches. Such patients continue to represent diagnostic challenges and high risk therapeutic options.

Adult↗
PubMed1992

Ureteroscopy without routine balloon dilation: an outcome assessment.

A retrospective analysis of 156 rigid ureteroscopic stone procedures in 145 patients revealed successful manipulation in 90%. The stone-free rate after adjunctive procedures was 95%. Access was achieved without balloon dilation in all but 18 patients. There were 24 perforations, occurring in 31% of proximal, 8% of mid ureteral and 8% of distal stone manipulations. Of the evaluable patients 63% underwent radiographic assessment for stricture disease, 75% at 6 months or more after the procedure. The stricture rate was 3.5% in all patients and 5.9% in patients with perforations. Of 37 patients evaluated for vesicoureteral reflux only 1 had reflux. Questionnaire followup was obtained for 74% of the patients (mean followup 2.6 years) and 32% felt normal within 3 days. Postoperative symptoms included flank pain (13%), renal colic (12%), pelvic discomfort (30%) and Double-J stent related complaints (49%). Of the patients 15% have reported recurrent stones. Ureteroscopy is effective and well tolerated, and it has minimal long-term complications.

Catheterization↗