A pilot study of a bioabsorbable self-reinforced poly L-lactic acid urethral stent combined with finasteride in the treatment of acute urinary retention from benign prostatic enlargement

Biodegradable braided poly(lactic-co-glycolic acid) urethral stent combined with dutasteride in the treatment of acute urinary retention due to benign prostatic enlargement: a pilot study

OBJECTIVE

To evaluate, in a pilot study, the efficacy and safety of combining a braided poly(lactic-co-glycolic acid) (PLGA, a copolymer of l-lactide and glycolide) urethral stent and dutasteride in the treatment of acute urinary retention (AUR) due to benign prostatic enlargement (BPE).

PATIENTS AND METHODS

Ten men with AUR due to BPE were treated as outpatients. A biodegradable braided PLGA urethral stent was inserted into the prostatic urethra, using a specially designed insertion device under visual control. Dutasteride treatment was started and the patients were followed up for 3 months after insertion of the stents.

RESULTS

In all patients the stents were placed successfully with the new insertion device. All men were able to void after inserting the stent. At 1 month five patients voided freely with a low residual urine volume (<150 mL), two voided but had a high residual urine volume and a suprapubic catheter was placed, and three needed a suprapubic or an indwelling catheter before 1 month, due to AUR or comorbidities. At 3 months five patients were voiding with no problems.

CONCLUSIONS

We have developed a new and effective insertion device for biodegradable braided prostatic stents. The new braided-pattern stent overcomes the earlier problems of migration and sudden breakage into large particles associated with biodegradable spiral stents. However, the mechanical properties of the new stent need to be improved and tested in a longer follow-up. We consider that this new biodegradable braided-pattern urethral stent could provide a new option in the future treatment of AUR.

Acute urinary retention in benign prostatic hyperplasia: Risk factors and current management

Acute urinary retention (AUR) is one of the most significant, uncomfortable and inconvenient event in the natural history of benign prostatic hyperplasia (BPH). The immediate treatment is bladder decompression using urethral or suprapubic catheterization. Several factors have been identified that are associated with or precipitate AUR. It is useful to classify AUR as BPH-related or not, than spontaneous or precipitated when the initial management is considered. Use of prophylactic 5 a-reductase inhibitors can prevent AUR in men with BPH having moderate to severe lower urinary tract symptoms and large prostate size. Alpha blockers can prevent AUR in symptomatic BPH patients and also facilitate catheter removal following episodes of spontaneous AUR. Anticholinergics can be safely combined with alpha blockers in symptomatic BPH patients without increasing the risk of AUR. Surgical treatment carries a higher rate of morbidity and mortality in men presenting with AUR compared to those presenting with symptoms alone. Urgent prostatic surgery after AUR is associated with greater morbidity and mortality than delayed prostatectomy. Alpha blockers mainly help to delay the surgery and may avoid surgery altogether in a subgroup of patients. TURP remains the "gold standard" if a trial without catheter fails. Alternative minimally invasive procedures can be considered in poor-risk patients, but its value is yet to be established.

Hourglass-shaped nitinol prostatic stent in treatment of patients with lower urinary tract symptoms due to bladder outlet obstruction

OBJECTIVES

To assess the efficacy and safety of the thermoexpandable hourglass-shaped nitinol prostatic stent in the treatment of patients with lower urinary tract symptoms due to bladder outlet obstruction.

METHODS

The stents were inserted in an outpatient setting under local anesthesia and direct vision. Five different stent lengths (2.0 to 4.0 cm) were used, depending on the length of the prostatic urethra. Assessment of voiding function and symptom scores was performed at baseline, directly after stent insertion, at 14 days, and 1, 3, 6, and 12 months after stent placement.

RESULTS

We enrolled 35 men in the trial. In 5 patients, insertion of the stent failed, mainly because of anatomical limitations. After all placement procedures, minimal temporary hematuria was observed. Spontaneous voiding was achieved in all patients, with immediate significant improvements in voiding parameters and symptom scores. The median indwelling time of the stent was 70 days. Kaplan-Meier survival analysis showed that at 14 days and at 3, 6, and 12 months, the stent was still in situ in 73%, 40%, 33%, and 23% of the patients, respectively. The main reason for removal of the stent was migration (93%), in most cases toward the bladder. Removal was uneventful in all but 1 case.

CONCLUSIONS

The placement of the thermoexpandable hourglass-shaped nitinol stent results in relief of outflow obstruction and improvement of symptom scores. Because of the high migration rate, however, this stent design needs further improvement to be suitable for clinical practice.

Bioartifizielle Materialien in der Urologie

The scope of our research is the development of polymer-based bioabsorbable stents for urologic applications and in vitro testing of tissue reactions of cultured ureteral and urethral segments induced by implanted polymer stent prototypes. For these purposes a tissue cultivation model was developed using selected techniques of tissue engineering. Essential advantages of degradable over nondegradable urethral stents are elimination of the adverse extraction of epithelialized stents and the potential for recovery of organ-specific functionality. Moreover, the biocompatibility of a degradable urethral stent could potentially reduce the risk of restenosis due to hyperplasia and could be used, even repeatedly, for the treatment of a number of subvesical obstructions. For the treatment of tumor-induced strictures, application of degradable polymer stents coated with cytostatic drugs may be possible. The mechanical effect of the drug-loaded stent as a "place holder" could be complemented by adjuvant or palliative approaches such as local chemotherapy. We have developed and tested in vitro a degradable urethral stent incorporated with the model drug methotrexate for local drug delivery (LDD) by diffusion and during stent degradation.

Acute Urinary Retention: a review of the aetiology and management

Acute retention of urine (AUR) is a common urological emergency characterised by a sudden inability to pass urine associated with lower abdominal pain. In recent years, the natural history and incidence of AUR has become better understood, however, further research into methods to prevent it and evaluation of the impact an episode of AUR has on the patient is required. This review provides an overview of the current management of AUR in men and the impact of the condition on patients' quality of life.

A double-blind, randomized, placebo-controlled pilot study to investigate the effects of finasteride combined with a biodegradable self-reinforced poly L-lactic acid spiral stent in patients with urinary retention caused by bladder outlet obstruction from benign prostatic hyperplasia

OBJECTIVE

To assess whether patients in acute urinary retention from benign prostatic enlargement can be treated with a combined therapy comprising finasteride and a bioabsorbable self-reinforced poly L-lactic acid (SR-PLLA) urethral stent.

PATIENTS AND METHODS

Fifty-five patients in acute urinary retention were treated as outpatients; they had a suprapubic catheter inserted and the SR-PLLA stent placed cystoscopically. After 2 weeks the patients were randomized to receive either finasteride 5 mg daily or placebo. They were assessed at baseline and at 6, 12 and 18 months for maximum urinary flow rate, prostate volume and serum prostate-specific antigen (PSA).

RESULTS

Nineteen patients completed the study while 36 discontinued. There was a statistically significant increase in the mean maximum flow rate, and a statistically significant decrease in the prostatic volume and serum PSA in the finasteride group. The same number of patients discontinued in both groups; the major reason for discontinuation was insufficient therapeutic response.

CONCLUSIONS

The major problems were discontinuation of treatment because the response to therapy was insufficient, and uncontrolled breakdown of the spiral stent. To solve these problems, new configurations of bioabsorbable stents are needed.