Abnormal spinal curvature and its relationship to pelvic organ prolapse

OBJECTIVE: Intra-abdominal vector forces have been implicated in the development of genital prolapse. Because the normal spinal curvature appears to protect the pelvic cavity from direct upper abdominal forces, variations in spinal curvature may alter these vector forces and possibly potentiate the development of pelvic organ prolapse. This study was undertaken to evaluate the relationship of spinal curvature and pelvic organ prolapse, specifically, the loss of lumbar lordosis or pronounced thoracic kyphosis. STUDY DESIGN: A total of 363 patients referred for various complaints of urinary incontinence or pelvic organ prolapse were included in this multicenter, prospective, case-control study. All patients underwent a detailed history with site-specific examinations; pelvic organ prolapse was quantitatively assessed according to the POPQ (pelvic organ prolapse quantitation) staging system. Spinal curvature was measured with a flexi-curve malleable rod when patients were in a fully erect position. Spinal curvature was then transferred to graph paper by tracing the flexi-curve. Thoracic and lumbar curvatures were determined by measuring thoracic and lumbar lengths and widths, respectively. RESULTS: Ninety-two patients had abnormal spinal curvature according to the study criteria. Complete loss of lumbar lordosis was found in 69 patients. Of the 92 patients with an abnormal curvature, 84 currently had or previously had pelvic organ prolapse (sensitivity, 91%). When compared with patients with a normal curvature, patients with an abnormal spinal curvature were 3.2 times more likely to have development of pelvic organ prolapse (odds ratio, 3.18; 95% confidence interval, 1.46 to 6.93; P = .002). There was no difference in the number of vaginal deliveries, weight of largest vaginally delivered infant, or body mass index. Only 11% (8/72) of patients with stage 0 prolapse had an abnormal spinal curvature, which increased to 30% (28/99) in patients with stage III prolapse (P = .042). CONCLUSION: An abnormal change in spinal curvature, specifically, a loss of lumbar lordosis, appears to be a significant risk factor in the development of pelvic organ prolapse.