Ultrastructure of detrusor and urethral smooth muscle in women with urinary incontinence,

Objective: We performed a quantitative study to determine whether mixed urinary incontinence was associated with any ultrastructural changes in detrusor and urethral smooth muscle. Study Design: Detrusor and urethral smooth muscle biopsy specimens were obtained at the time of laparotomy from 5 women aged 35 to 65 years with mixed urinary incontinence and from a control group of 5 continent women. Smooth muscle morphologic characteristics were assessed from a systematic random sample of electron micrographs. A further 16 urethral biopsy specimens were similarly analyzed to confirm the findings of the initial study. Results: The electron-dense portion of the sarcolemma was smaller in urethral biopsy specimens taken from patients with intrinsic sphincter deficiency than in those from control subjects (χ2(1) = 4.9; P = .027). No other morphologic characteristics were unique to patients with incontinence. Conclusions: Our study suggests that focal adhesion architecture is decreased in urethral smooth muscle of patients with intrinsic sphincter deficiency. (Am J Obstet Gynecol 2000;182:879-84.)