Negative-resistance effects in flow through collapsible tubes: 2 two-dimensional theory of flow near an elastic constriction.
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Biomedical subjects
Publications and source records attributed to D J Griffiths.
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There is no dispute that there exists, in men, a condition of obstruction at the bladder neck in the absence of fibrous stricture or prostatic enlargement. The condition was clearly described by Guthrie (1836) and Young (1913) reported the results ff punch resection operation in over 50 cases. The large measure of success now achieved following resection of the bladder neck in these patients has perhaps been allowed to mask our ignorance of the nature of the abnormality and thus discourage studies of its cause. It is perhaps most often thought to result from fibrosis but a number of studies--for example Baadenoch (1949)--have shown no associated increase in fibrous tissue. Certainly the condition is in no way similar to the hard fibrous stricture seen more often in the distal urethra, or at the bladder neck as an occasional complication of prostatectomy. Our study shows that the obstruction if functional in nature and is due to the tightening of the bladder neck as the detrusor contracts.
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The goal of this study was to determine whether a .5-T open configuration magnet system could be used to evaluate the female pelvic floor support structures and their functional changes in the upright and supine positions. We evaluated five normal volunteers with full bladders in the supine and sitting positions. Multiple measurements were obtained, including distance between symphysis and urethra, bladder neck to fixed pubococcygeal line, and posterior urethrovesical angle. The pelvic floor was evaluated for integrity of the urethra, vagina, and supporting ligaments. High quality, interpretable images were obtained for all five patients in both positions. Most of the pelvic floor structures were stable, with the exception of the posterior urethrovesical angle, which increased in the sitting position. We conclude that the vertically open configuration magnet system shows promise for evaluation of the female pelvic floor, including urinary stress incontinence and prolapse.
OBJECTIVE: To (1) utilize videourodynamics, the gold standard, to assess the prevalence of occult genuine stress incontinence (GSI) among preoperative patients with symptomatic anterior vaginal wall relaxation and (2) identify urodynamic discriminators that might help predict occult GSI. METHODS: In this prospective study, videourodynamic evaluation was performed on 48 consecutive patients presenting for preoperative urodynamic evaluation of anterior vaginal wall prolapse. Patients with occult GSI were identified by urodynamic testing with and without Gehrung pessary support of the bladder base during stress maneuvers. Variables from the history, physical examination, and videourodynamics were then analyzed. RESULTS: The overall incidence of occult GSI was 25% (22.7% in the pelvic organ prolapse [POP] group and 26.9% in the POP-UI group). Patients with occult GSI were not identifiable on history but did have a higher incidence of late first sensation, open bladder neck at rest, and hypermobility on imaging with videourodynamics. CONCLUSION: This study suggests that one quarter of women presenting with anterior wall relaxation with or without incontinence symptoms have occult GSI. Given this high prevalence, preoperative evaluation with urodynamics, possibly videourodynamics, utilizing bladder base support is justified if the data are substantiated in a larger, definitive study. Patients with a late first sensation, open bladder neck, and hypermobility may have a higher incidence of occult GSI.