The appearance of levator ani muscle abnormalities in magnetic resonance images after vaginal delivery

doi:10.1016/S0029-7844(02)02465-1

Obstetrics & Gynecology

Volume 101, Issue 1, January 2003, Pages 46-53

https://doi.org/10.1016/S0029-7844(02)02465-1 Get rights and content

Abstract

Objective

To describe the appearance and occurrence of abnormalities in the levator ani muscle seen on magnetic resonance imaging (MRI) in nulliparous women and in women after their first vaginal birth.

Methods

Multiplanar proton density magnetic resonance images were obtained at 0.5-cm intervals from 80 nulliparous and 160 vaginally primiparous women. These had been previously obtained in a study of stress incontinence, and half the primiparas had stress incontinence. All scans were reviewed independently by at least two examiners blinded to parity and continence status.

Results

No levator ani defects were identified in nulliparous women. Thirty-two primiparous women (20%) had a visible defect in the levator ani muscle. Defects were identified in the pubovisceral portion of the levator ani in 29 women and in the iliococcygeal portion in three women. Within the pubovisceral muscle, both unilateral and bilateral defects were found. The extent of abnormality varied from one individual to the next. Of the 32 women with defects, 23 (71%) were in the stress incontinent group.

Conclusion

Abnormalities in the levator ani muscle are present on MRI after a vaginal delivery but are not found in nulliparas.

Section snippets

Materials and methods

Magnetic resonance images of the pelvis were obtained from 240 women as part of an institutional review board–approved study concerning vaginal delivery and stress urinary incontinence. Multiplanar two-dimensional fast spin (echo time 15 ms, repetition time 4000 ms) proton density magnetic resonance images of all pelves were obtained by use of a 1.5-tesla superconducting magnet (Signa; General Electric Medical Systems, Milwaukee, WI) with version 5.4 software as previously described.1 Images 5

Results

There were 32 women (20%) with a visible defect in one or both levator ani muscles among the 160 parous women in the study. Of these, 29 (18%) involved the pubovisceral portion of the muscle and three (2%) involved the iliococcygeal portion. Of the 80 women who were incontinent, 23 (28%) had a defect in the levator ani muscle, and of the 80 primiparous continent women, nine (11%) had a defect, making stress incontinent primiparas twice as likely to have a muscle abnormality. No defects were

Discussion

Abnormalities have previously been demonstrated in the levator ani muscles of women with stress urinary incontinence7 and pelvic organ prolapse,8 using magnetic resonance imaging (MRI). These abnormalities could be a variant of normal anatomy, they could be a distortion caused by abnormal pelvic organ positions, or they could be damage that occurred during vaginal delivery. Our study depicts levator ani muscle damage after vaginal birth and provides the first scientific evidence that supports

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Cited by (520)

Pelvic floor injury during vaginal birth is life-altering and preventable: what can we do about it?
2024, American Journal of Obstetrics and Gynecology
Pelvic floor disorders after childbirth have distressing lifelong consequences for women, requiring more than 300,000 women to have surgery annually. This represents approximately 10% of the 3 million women who give birth vaginally each year. Vaginal birth is the largest modifiable risk factor for prolapse, the pelvic floor disorder most strongly associated with birth, and is an important contributor to stress incontinence. These disorders require 10 times as many operations as anal sphincter injuries. Imaging shows that injuries of the levator ani muscle, perineal body, and membrane occur in up to 19% of primiparous women. During birth, the levator muscle and birth canal tissues must stretch to more than 3 times their original length; it is this overstretching that is responsible for the muscle tear visible on imaging rather than compression or neuropathy. The injury is present in 55% of women with prolapse later in life, with an odds ratio of 7.3, compared with women with normal support. In addition, levator damage can affect other aspects of hiatal closure, such as the perineal body and membrane. These injuries are associated with an enlarged urogenital hiatus, now known as antedate prolapse, and with prolapse surgery failure. Risk factors for levator injury are multifactorial and include forceps delivery, occiput posterior birth, older maternal age, long second stage of labor, and birthweight of >4000 g. Delivery with a vacuum device is associated with reduced levator damage. Other steps that might logically reduce injuries include manual rotation from occiput posterior to occiput anterior, slow gradual delivery, perineal massage or compresses, and early induction of labor, but these require study to document protection. In addition, teaching women to avoid pushing against a contracted levator muscle would likely decrease injury risk by decreasing tension on the vulnerable muscle origin. Providing care for women who have experienced difficult deliveries can be enhanced with early recognition, physical therapy, and attention to recovery. It is only right that women be made aware of these risks during pregnancy. Educating women on the long-term pelvic floor sequelae of childbirth should be performed antenatally so that they can be empowered to make informed decisions about management decisions during labor.
Evaluating changes in the strength of the levator ani muscle after vaginal delivery using T2-parameter mapping
2023, European Journal of Radiology
To evaluate pelvic floor muscle injury in patients with levator ani muscle (LAM) weakness after vaginal delivery using T2-parameter mapping.
40 parturients (patient group) and 25 nonparturients (healthy control group) were enrolled in the study. The LAM weakness group had a Modified Oxford Grading System (MOGS) grade of less than 3 after vaginal delivery. All participants underwent pelvic magnetic resonance imaging (MRI) scans, including T2 and T2* mapping, on which the main branches of the LAM, the puborectalis and iliococcygeus, were evaluated. The differences in T2 and T2* values in the puborectalis and iliococcygeus between patients with LAM weakness and controls were analyzed using an independent samples t test or a Mann–Whitney U test.
For both the right and left iliococcygeus, the T2* values of the patient group were lower than those of the control group (P = 0.002 and 0.008, respectively), while no significant difference was observed in the T2 values between the groups (P = 0.45 and 0.69, respectively). For both the right and left puborectalis, no significant differences in the T2* (P = 0.25 and P = 0.25, respectively) or T2 values (P = 0.38 and 0.43, respectively) were observed between the patient and control groups.
T2* mapping as a quantitative measurement is an effective imaging tool to assess LAM injury in women after vaginal delivery. The iliococcygeus was more susceptible to vaginal delivery damage than the puborectalis, and pelvic floor dysfunction may be mainly driven by iliococcygeus injury.
Influence of prenatal urinary incontinence and mode of delivery in postnatal urinary incontinence: A systematic review and meta-analysis
2023, Journal of Gynecology Obstetrics and Human Reproduction
It is likely that the pathophysiology of urinary incontinence (UI) differs between women who are incontinent before the first delivery and those whose incontinence occurs after. In this systematic review, we aimed to assess the association between the mode of delivery and the risk of postpartum UI in primiparous women with and without prenatal UI.
We searched MEDLINE, Cochrane, Web of Science, Embase and CINHAL databases. Prospective studies including primiparous women during their pregnancy with a comparison of the rate of postpartum UI in women who underwent cesarean delivery or vaginal delivery according to continence status before delivery were included. The Risk Ratio (RR) was calculated with a 95% confidence interval (95% CI) using the total number of events and patients extracted from the individual studies. A subgroup comparison analysed the potential influence of women's prenatal continence status. Heterogeneity was estimated using I² statistics.
The risk of postpartum UI was significantly higher after vaginal delivery than after cesarean section (RR 1.80, 95% CI 1.48- 2.18). According to the subgroup test, the postpartum UI risk following a vaginal delivery, compared to cesarean section, was significantly higher in the subgroup of continent women during pregnancy (RR 2.57, 95% CI 2.17–3.04) than in the subgroup of incontinent pregnant women (1.56, 95% CI 1.27–1.92).
The effect of a cesarean section in preventing postpartum UI appears controversial, particularly in women with prenatal UI.
A review of levator ani avulsion after childbirth: Incidence, imaging and management
2022, Midwifery
Key Content
• Levator ani muscle (LAM) avulsion injury occurs occultly during childbirth, most commonly during operative vaginal deliveries.
• Injuries of levator ani have long term sequelae for pelvic floor health. As life expectancy increases the burden of disease upon urogynaecology services will need to be considered.
• Diagnosis of this condition can be difficult as there is no agreed ‘gold standard’ imaging modality.
• There is no consensus regarding surgical management of LAM avulsion.
Learning objectives
• Review anatomy and function of levator ani muscle
• Identify the risk factors for levator ani avulsion injury
• Role of imaging to appropriately identify LAM injury and current management options including appropriate follow up
• Management of subsequent pregnancy following LAM avulsion
Ethical issues
• Is there value to the patient in diagnosing levator ani avulsion when there is no recommended treatment for these injuries?
Morphological examination of pelvic floor muscles in a rat model of vaginal delivery
2024, BMC Pregnancy and Childbirth
Twisted orientation of the muscle bundles in the levator ani functional parts in women: Implications for pelvic floor support mechanism
2024, Journal of Anatomy

View all citing articles on Scopus

^☆: Supported by National Institutes of Health grants R01 DK51405 and R01 HD38665.

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Regular paperThe appearance of levator ani muscle abnormalities in magnetic resonance images after vaginal delivery☆

Abstract

Objective

Methods

Results

Conclusion

Section snippets

Materials and methods

Results

Discussion

Am J Obstet Gynecol

Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

Am J Obstet Gynecol

MR imaging of levator ani muscle recovery following vaginal delivery

Int Urogynecol J

Pelvic anatomy I. Pelvic floor muscles

Ann R Coll Surg Engl

The contribution of magnetic resonance imaging of the pelvic floor to the understanding of urinary incontinence

Br J Urol

Static magnetic resonance imaging of the pelvic floor muscle morphology in women with stress urinary incontinence and pelvic prolapse

Neurourol Urodyn

Epidemiology of genital prolapseObservations from the Oxford Family Planning Association study

Br J Obstet Gynaecol

Factors associated with risk of stress urinary incontinence in women

Nurs Res

The symptom of stress incontinence caused by pregnancy or delivery in primiparas

Obstet Gynecol

Regular paper
The appearance of levator ani muscle abnormalities in magnetic resonance images after vaginal delivery☆