An in vitro investigation of the effect of bevel design on the penetration and withdrawal forces of dental needles.

OBJECTIVES: To compare the effect on insertion and withdrawal forces using needles with a standard atraumatic bevel to those with a novel asymmetrical bevel in vitro. METHODS: Maximum needle penetration forces were measured using a 10N load cell mounted on an Instron universal testing machine. Forces were determined during insertion through a 0.4mm polyurethane membrane mounted at 90° (n=30 of each design), 30° (n=16 of each design) and 150° (n=16 of each design) to the needle bevel and during a 10mm insertion into a polyvinyl siloxane block mounted at 90° to the bevel (n=16 of each design). In all tests the rate of insertion was 50mm/min. RESULTS: The novel design required less force to penetrate the membrane at 30° and 150° compared to the standard design (mean forces at 30° being 0.75N and 0.98N for novel and standard designs respectively [p<0.001] and at 150° 0.52N and 0.66N respectively [p<0.001] but more force at 90° penetration tests (0.60N and 0.46N respectively [p<0.001]). The novel design required less force to insert 10mm into the polyvinyl siloxane (1.80N and 2.54N respectively [p<0.001]). CONCLUSION: The novel design needed less force than the standard version to penetrate a thin membrane when used at 30° and 150° to the surface and to penetrate a polyvinyl siloxane block to a depth of 10mm but required more force to penetrate a thin membrane at 90°. CLINICAL SIGNIFICANCE: Needle bevel design affects the penetration and withdrawal forces of dental needles in vitro.

A randomized, double-blind placebo-controlled trial of the effects of the 5-hydroxytriptamine(4) agonist cisapride on the female urinary bladder.

OBJECTIVE: Anecdotal reports have proposed the use of the 5-hydroxytriptamine(4) agonist cisapride as a treatment for female voiding dysfunction on the basis of the known prokinetic actions of the medication. The purpose of our study is to assess the effects of this agent on the normal bladder in vivo. STUDY DESIGN: In this randomized, double-blind placebo-controlled trial, patients were randomized to receive either 20 mg cisapride or an identical placebo. They then underwent urodynamic evaluation that included uroflowmetry, multichannel filling cystometry, pressure-flow studies, and a urethral pressure profile. After a washout period of at least 7 days, subjects were then crossed over to the other arm and the tests were repeated. RESULTS: Twenty women without significant urinary incontinence agreed to participate. There was a decrease in the maximum cystometric capacity from 556 mL for placebo to 496 mL for cisapride (P <.001). There was no difference in the detrusor pressure at maximum flow, the maximum detrusor pressure, the flow rate, or the percentage of maximum cystometric capacity voided. CONCLUSIONS: In healthy women, cisapride caused a significant decrease in the maximum cystometric capacity, which could account for the higher reported rates of urinary frequency and urgency with this medicine. There was no evidence that this prokinetic agent improved voiding function.

Anatomic and functional outcome of vaginal paravaginal repair in the correction of anterior vaginal wall prolapse.

Over a 2-year period 45 patients with bilateral paravaginal support defects underwent vaginal paravaginal repair. Postoperative evaluations were conducted and anatomic outcome was determined by vaginal examination, with grading of vaginal wall support. Functional outcome was assessed by a standardized quality of life questionnaire, voiding dairy and standing stress test with a full bladder. Thirty-five patients had long-term follow-up with a mean of 1.6 years (range 1-85). The recurrence rates for displacement cystocele, enterocele and rectocele were 3% (1/35), 20% (7/35) and 14% (5/35), respectively. In no patients did vault prolapse develop or recur. Subjective or objective evidence of persistent stress urinary incontinence was found in 57% of patients (12/21). Vaginal paravaginal repair is a safe and effective technique for the surgical correction of anterior vaginal wall prolapse but has limited applicability in the surgical correction of genuine stress incontinence.

Periurethral collagen injection for stress incontinence with and without urethral hypermobility.

OBJECTIVE: To compare the use of periurethral collagen injection in the treatment of female stress urinary incontinence due to intrinsic sphincter deficiency in women with and without urethral hypermobility. METHODS: A retrospective review was performed of 60 periurethral collagen injections performed on 40 consecutive women from January 1996 to December 1997. A review of the office chart and operative notes was performed to obtain demographic, urodynamic, and procedural data. Outcome data were obtained by personal or telephone interview, using patients' subjective assessments including an analog satisfaction scale. RESULTS: Nine of 40 patients (23%) had urethral hypermobility. Compared with patients without hypermobility, patients with hypermobility required a similar number of procedures (a mean of 1.9 compared with 1.4, P = .13) and required similar amounts of collagen on the first injection (5.6 mL compared with 5.3 mL, P = .69). Preoperative urodynamic parameters were similar in both groups. Rates of subjective dryness were equivalent in patients with and without hypermobility at 1 month (76% and 46%, P = .24) and at 6 months (71% and 32%, P = .09) following initial injection. A post hoc power analysis was performed to evaluate the primary study measures of continence at 1 and 6 months, and number of collagen injections. This revealed that a sample size of 40 patients would be sufficient to detect a 2.5-fold difference in number of injections and a 3-fold difference in subjective dryness. CONCLUSION: Coexisting urethral hypermobility should not preclude the use of collagen injections in women with stress urinary incontinence.

Pharmacologic causes of female incontinence.

The etiology of female urinary incontinence is complex and multifactorial. Many medications have adverse effects on the lower urinary tract, including the promotion of incontinence in certain women. Medications may cause incontinence through three main mechanisms: decreased intraurethral pressure, increased intravesical pressure, and indirect effects on the lower urinary tract. Careful adjustments of a patient's medications based on a knowledge of pharmacologic mechanisms of action may restore continence in some women.