CME Author: Vicki Brower
Study Authors: Joan L. Blomquist, Alvaro Muñoz, et al.
Target Audience and Goal Statement:
Obstetricians/gynecologists, urologists, internists, and women’s health specialists
The goals were to identify the incidence of pelvic floor disorders after childbirth and identify maternal and obstetrical characteristics associated with patterns of incidence at 1-2 decades post-partum.
- What is the incidence of stress urinary incontinence, overactive bladder, anal incontinence, and pelvic organ prolapse in the two decades following delivery?
- How are these incidences associated with three delivery types: cesarean, spontaneous vaginal and non-operative vaginal births, and operative vaginal births?
Study Synopsis and Perspective:
The risk of 4 pelvic floor disorders for women 1-2 decades after childbirth varied according to delivery mode, a new study found.
Women who delivered via cesarean section had a lower hazard of stress urinary incontinence (SUI), overactive bladder (OAB), and pelvic organ prolapse (POP) compared with women who had spontaneous vaginal deliveries, reported Joan L. Blomquist, MD, of Greater Baltimore Medical Center in Maryland, and colleagues. Researchers also found that operative vaginal delivery was associated with a higher hazard of anal incontinence (AI) and pelvic organ prolapse, they wrote in JAMA.
“Little is known, however, about the association of various obstetrical exposures with the course and progression of pelvic floor disorders during a woman’s life,” they wrote.
To investigate this relationship, researchers examined data from the Mother’s Outcomes After Delivery study, a longitudinal cohort study of parous women, in which participants were recruited from a community hospital 5-10 years after their first delivery, and followed annually for up to 9 years.
Women were examined by mode of delivery: C-section, spontaneous vaginal birth (≥1 spontaneous vaginal delivery and no operative vaginal deliveries), or operative vaginal birth.
Four pelvic floor disorders were assessed annually via the Epidemiology of Prolapse and Incontinence Questionnaire (EPIQ), as well as a physical examination, the authors said. They included:
- Stress urinary incontinence
- Overactive bladder
- Anal incontinence
- Pelvic organ prolapse
Overall, data were examined from 1,528 study participants — 778 women in the C-section birth group, 565 women in the vaginal birth group, and 185 in the operative vaginal birth group. Median age at first delivery was about 30, while median age at enrollment was about 38. There were 28% of women with one delivery, 56% with two, and 16% with three or more deliveries. In addition, 72% of women were multiparous at enrollment.
They found that during a median follow-up of about 5 years, there were 138 cases of stress urinary incontinence, 117 cases of overactive bladder, 168 cases of anal incontinence, and 153 cases of pelvic organ prolapse.
Importantly, these varied depending on mode of delivery. The researchers found that compared with spontaneous vaginal delivery, C-section delivery was associated with significantly lower hazard of stress urinary incontinence (adjusted HR 0.46, 95% CI 0.32-0.67), overactive bladder (adjusted HR 0.51, 95% CI 0.34-0.76), and pelvic organ prolapse (adjusted HR 0.28, 95% CI 0.19-0.42).
However, operative vaginal delivery was associated with a significantly higher hazard of anal incontinence (adjusted HR 1.75, 95% CI 1.14-2.68) and pelvic organ prolapse (adjusted HR 1.88, 95% CI 1.28-2.78). The authors also found that “the association with delivery mode was the most pronounced for [pelvic organ prolapse].”
Additionally, the hazard ratios for POP, relative to a genital hiatus size less than or equal to 2.5cm, were 3.0 (95% CI, 1.7-5.3) for a genital hiatus size of 3 cm and 9.0 (95%CI, 5.5-14.8) for a genital hiatus size greater than or equal to 3.5 cm, the researchers reported. Genital hiatus is defined as the distance (in centimeters) from the middle of the external urethral meatus to the posterior midline hymen measured during the maximal Valsalva maneuver.
In discussing how their study provided “a more complete picture” of the incidence of these examined pelvic floor disorders over time, the authors observed that “[pelvic organ prolapse]… had a longer latency after childbirth than [stress urinary incontinence] and [anal incontinence].” Such “temporal differences” could explain the different patterns seen in surgery for pelvic organ prolapse and stress urinary incontinence.
Source Reference: JAMA, Dec. 18, 2018; 320(23):2438-2447
Study Highlights: Explanation of Findings
Overall, the cumulative incidence of each pelvic floor disorder was significantly associated with delivery mode, with substantial difference in disorder incidence based on a woman’s “obstetrical characteristics.” Researchers noted that prior research found that about a quarter of U.S. women during 2005 to 2006 had one or more pelvic floor disorders, with the rate more than doubling for women ages ≥80, rendering them a significant public health issue.
Researchers found that the hazard of each pelvic floor disorder was highest among women who had operative vaginal birth(s) and lowest among those who had C-section(s). Regarding the temporal issue, they found that the risk for stress-urinary incontinence showed “a very sharp rise” in the hazard rate within the first 5 years of delivery, “corresponding with the observed pattern of early onset for this condition.” This contrasted with POP, for which the peak hazard rate was estimated to occur more than 20 years post-delivery. The annual risk of surgery for SUI had 2 peaks, at ages 46 and 70-71, whereas the annual risk of surgery for POP increased with age, with the highest risk for women ages 71-73.
The between-group differences for SUI were greatest in the first few years, but waned after that. In contrast, the differences between delivery groups remained over time for POP.
“The difference in latency observed in the present study may also suggest different causation of the various pelvic floor disorders,” Blomquist and colleagues wrote. For example, there is growing evidence that some cases of POP may be caused by trauma to the levator ani muscle, which is often not evident at time of delivery. However, imaging studies “have detected significant trauma to this muscle after 10-20% of vaginal deliveries.” The effect of this injury “appears to evolve over decades, resulting in a long latency for symptomatic POP,” they wrote. “In contrast, the urethral sphincteric mechanism may be a stronger predictor of symptoms of incontinence, and injury to that mechanism with vaginal delivery may explain the relatively early onset after delivery for incontinence disorders.”
Interestingly, black women had a reduced hazard to developing AI (aHR, 0.42 [95%CI, 0.24-0.73]) and obese women were at significantly greater hazard of developing both SUI (aHR, 1.97 [95% CI, 1.29-3.01]) and AI (aHR, 2.24 [95% CI, 1.53-3.20]). Parity of at least 3 was significantly associated with an increasing hazard of POP (aHR, 2.08 [95% CI, 1.19-3.64]). However, researchers found that age at first delivery was not associated with the hazard of any of these conditions.
Researchers also found that genital hiatus size was significantly associated with each of the 4 pelvic floor disorders. Additional analysis showed that for each of the 3 delivery modes, there were significant associations between increasing genital hiatus size and the incidence of pelvic floor disorders. This association was most notable for POP, they wrote. For women with the same delivery mode and relative to genital hiatus size of 2.5 cm or less, the HRs for POP were 3.0 (95% CI, 1.7-5.3) for a genital hiatus size of 3 cm, and 9.0 (95% CI, 5.5-14.8) for a genital hiatus size greater than or equal to 3.5 cm. This association existed in each of the delivery groups. As genital hiatus size was significantly associated with hazard for all 4 disorders, especially POP, this may be able to be employed as a marker to monitor risk of POP over time. Changes in genital hiatus may in fact be a mechanism for POP development, regardless of delivery mode, they concluded.
Study strengths included the length of the cohort study and the longitudinal design. Study limitations included potential misclassification of pelvic floor disorders, as well as use of “dichotomous definitions” of pelvic floor disorders, as the authors noted that “worsening of a mild pelvic floor disorder over time may also be clinically relevant.” They also stated that while this may be the longest cohort study on the epidemiology of pelvic floor disorders to date, “the duration of follow-up was not adequate to look at patterns of hazard in older women.”
Molly Walker wrote the original story for MedPage Today.