Objective
We sought to compare pelvic floor structure and function between older women with and without fecal incontinence (FI) and young continent (YC) women.
Study Design
YC (n = 9) and older continent (OC) (n = 9) women were compared to older women with FI (older incontinent [OI]) (n = 8). Patients underwent a pelvic organ prolapse quantification, measurement of levator ani (LA) force at rest and with maximum contraction, and magnetic resonance imaging. Displacement of structures and LA defects were determined on dynamic magnetic resonance imaging.
Results
LA defects were more common in the OI vs the YC (75% vs 11%, P = .01) and OC (22%, P = .14) groups; women with FI were more likely to have LA defects than women without (odds ratio, 14.0, 95% confidence interval, 1.8–106.5). OI women generated 27.0% and 30.1% less force during maximum contraction vs the OC ( P = .13) and YC ( P = .04) groups. During Kegel, OI absolute structural displacements were smaller than in the OC group ( P = .01).
Conclusion
OI women commonly have LA defects, and cannot augment pelvic floor strength.
With aging, the prevalence of fecal incontinence (FI) increases. FI is a debilitating condition and a common cause of institutionalization in the elderly, yet the mechanisms underlying FI are still not fully understood. Fecal continence is maintained by a complex sphincter system involving 3 anatomical elements: the smooth muscle internal anal sphincter, the striated external anal sphincter (EAS), and levator ani (LA) muscles. Failure of each of these elements has been implicated in the multifactorial etiology of FI, however, how much the failure of each these individual components, especially the LA, contribute to FI has not been reported.
It is known that LA muscle defects are associated with pelvic organ prolapse (POP) and difficult vaginal delivery. In addition, Nichols et al found that anal incontinence was more common in women with pelvic floor disorders (including POP and/or urinary incontinence) than normal controls. However, the association of LA defects with FI is still unclear. The aims of this study were 2-fold. First, it was our objective to examine the relationship of LA muscle structure as it relates to FI in older women using dynamic magnetic resonance (MR) imaging (MRI). Second, we sought to examine changes in the function of the pelvic floor (specifically, force of LA contraction and movement of perineal structures with Kegel and Valsalva) that occur in older women with FI.
Materials and Methods
We recruited 8 older women with weekly FI aged 63-85 years (older incontinent [OI]) as well as 9 young continent (YC) women aged 20-41 years and 9 older continent (OC) women aged 60-88 years (representing asymptomatic continent control groups) from February 2006 through October 2007. Due to funding limitations, young incontinent women were not recruited. Subjects were recruited through the university-based gynecology clinic and campus-wide advertisements. All were community dwelling. The study was approved by the university’s institutional review board (#2005-0294).
As previously described, older women who reported loss of solid stool ≥1/wk and had a Wexner score of >8 were considered cases. Women who reported only incontinence of gas/flatus or reported the use of a pad or lifestyle alterations without reporting loss of solid stool were not included. Continent controls (both older and younger) had to have a Wexner score of <4. Exclusion criteria was as follows: previous gynecological surgery for pelvic floor disorders and prolapse, previous anal sphincter repair surgery, current treatment for cancer, chronic use of steroids, human immunodeficiency virus–positive status, sickle cell disease, irritable bowel syndrome (based on Rome III criteria), neurological conditions, uncontrolled diabetes, stroke, or Alzheimer disease. Women who had undergone hysterectomy were eligible if the indication for the surgery was not prolapse and occurred at least 1 year before enrollment.
To assess vaginal and uterine support, all women were examined using POP quantification (POPQ) measurements in the semirecumbent position at a 45-degree angle. To assess LA muscle function, an instrumented speculum examination was performed to measure LA muscle force with maximal contraction (F LAC ) and at rest as previously described in our group’s work.
Women also underwent transrectal ultrasound as reported in our previous study. All women also underwent dynamic, supine MRI of the pelvic floor. Images were taken in the axial, saggital, and coronal planes using a fast spin proton density technique. Scans were performed on a 1.5-T superconducting magnet (Signa; General Electric Medical Systems, Milwaukee, WI). Slice thickness was 4 mm, with a gap of 1 mm, yielding 5-mm image spacing. A total of 20 mL of ultrasound gel was added to the vagina to better delimit its location and boundaries.
Using an identification and grading system for LA defects (encompassing both the pubovisceral and puborectal portions of the muscle) previously described by our group, muscle defects were identified on static, axial images in all 3 groups. Examiners were blinded to the age and continence status of all of the subjects.
On static, midsagittal MRI at rest, maximum Kegel, and maximum Valsalva, a sacrococcygeal-inferior pubic point (SCIPP) line (x-axis) and perpendicular y-axis were drawn. Using these axes as references, measurements of levator and urogenital hiatus diameters were made in all 3 groups and compared. The angle of the levator plate was measured relative to the SCIPP line as well. When the levator plate was parallel to SCIPP line, the angle was considered zero. When the angle was above the parallel in a clockwise direction, it was considered negative. When it was below the parallel in a counterclockwise direction, the angle was considered positive. Similarly, on dynamic images, locations of the perineal body (PB) and EAS were determined as x and y coordinates in centimeters relative to these axes, again at rest, maximum Kegel, and maximum Valsalva ( Figure 1 ). Using these x and y coordinates, displacements of the PB and EAS from rest to maximum Kegel as well as from rest to maximum Valsalva in each individual were calculated. All measurements were made using software (Image J 1.4l; National Institutes of Health, Bethesda, MD).
All statistical analyses were completed using software (SPSS, Version 16.0; SPSS, Inc, Chicago, IL). Bivariate relationships were explored among the OI, OC, and YC group POPQ points and MRI measures using analysis of variance. Additional pairwise comparisons with Student t tests were made when a significant difference between the groups was detected with analysis of variance. To determine whether LA defects were associated with continence status, the OC and YC groups were combined and compared to the OI group. Logistic regression analyses with and without adjustment for EAS defects were conducted to determine associations between LA defects in women with FI (OI) and those without (OC + YC) as well. An alpha of ≤0.05 was used for significance in all tests.
Results
The demographics of the OI, OC, and YC groups are shown in Table 1 . No significant differences were observed between the OI and OC groups. The OI group was significantly older than the YC group and had more vaginal and forceps-assisted deliveries. The OC group was also older and had more vaginal deliveries than the YC group. All 3 groups were similar with respect to number of bowel movements per week (OI = 9.9 ± 2.3, OC = 7.6 ± 1.2, YC = 8.3 ± 1.3; P = .34).
| Variable | OI (n = 8) | OC (n = 9) | OI vs OC P value | YC (n = 9) | OI vs YC P value | OC vs YC P value |
|---|---|---|---|---|---|---|
| Mean age, y (SD) | 71.6 (7.5) | 71.6 (7.5) | .8 | 28.7 (7.3) | < .001 | < .001 |
| Mean BMI, kg/m 2 (SD) | 27.6 (4.2) | 25.4 (4.3) | .3 | 27.2 (7.4) | .9 | .5 |
| Mean vaginal parity, n (SD) | 2.6 (1.2) | 2.8 (1.7) | .8 | 0.2 (0.4) | < .001 | < .001 |
| Mean forceps-assisted deliveries, n (SD) | 1.0 (1.1) | 0.6 (1.0) | .4 | 0 | < .001 | .1 |
| Mean cesarean sections, n (SD) | 0.1 (0.4) | 0 | .4 | 0.1 (0.3) | .9 | .3 |
Differences in pelvic organ support on POPQ examination among the OI, OC, and YC groups are shown in Table 2 . No significant differences in POPQ were seen between the 2 groups of older women (OI and OC). The OI group had less anterior vaginal wall support than YC group (points Aa and Ba); apical support (point D) was also diminished in the OI group compared to the YC group. Posterior support, genital hiatus, and PB measurements did not differ significantly between the OI and YC groups. Total vaginal length was slightly longer in the YC group compared to the OI group. Point D in the OC group was less than the YC group as well. None of the women had prolapse outside of the hymen.
| POPQ measure in cm, mean (SD) | OI (n = 8) | OC (n = 9) | OI vs OC P value | YC (n = 9) | OI vs YC P value | OC vs YC P value |
|---|---|---|---|---|---|---|
| Aa | –0.3 (2.0) | –1.4 (1.4) | .2 | –2.4 (0.7) | .01 | .1 |
| Ba | –0.1 (2.6) | –1.5 (1.2) | .1 | –2.4 (0.7) | .02 | .1 |
| C | –5.3 (4.1) | –7.1 (0.8) | .2 | –7.6 (1.5) | .2 | .5 |
| D | –5.8 (4.3) | –7.9 (1.2) | .2 | –9.6 (1.1) | .03 | .01 |
| Ap | –1.0 (2.4) | –1.6 (1.5) | .5 | –2.3 (0.9) | .1 | .3 |
| Bp | –1.6 (1.0) | –1.6 (1.5) | .9 | –2.3 (0.9) | .1 | .3 |
| GH | 3.7 (1.8) | 2.6 (0.7) | .1 | 2.4 (0.5) | .1 | .5 |
| PB | 3.0 (1.8) | 4.1 (1.7) | .9 | 3.5 (0.9) | .2 | .2 |
| TVL | 9.3 (1.0) | 9.4 (1.4) | .8 | 10.3 (0.9) | .04 | .2 |
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