By Chiara Ghetti, MD
Associate Professor, Obstetrics and Gynecology, Division of Female Pelvic Medicine and Reconstructive Surgery, Washington University School of Medicine, St. Louis
Dr. Ghetti reports no financial relationships relevant to this field of study.
SYNOPSIS: Significant changes in levator muscles are visible by transperineal ultrasound in early and late postpartum period.
SOURCE: Aydin S, Aydin ÇA. Evaluation of labor-related pelvic floor changes 3 months after delivery: A 3D transperineal ultrasound study. Int Urogynecol J 2015;26:1827-1833.
The objective of this study was to document changes in levator ani (LA) morphology and levator and genital hiatus measurements by transperineal ultrasound immediately after vaginal delivery and at 3 months post-delivery. This was a prospective cohort (cross-sectional observational) study of 94 primiparous women. Women were examined within 36 hours of vaginal delivery (early evaluation) and 3 months after delivery (late evaluation). Primary outcomes were transperineal 3D ultrasound measurements, including maximum anteroposterior and transverse diameters of levator hiatus at rest and with Valsalva, pubovisceral muscle thickness to left and right of rectum, difference in the anteroposterior and transverse diameters of the hiatus, and difference in levator hiatus between rest and during Valsalva maneuver. Women were excluded who underwent operative delivery, multifetal pregnancy, cesarean delivery, inability to assume lithotomy position, refusal to provide consent, and inability to generate an effective Valsalva maneuver.
Eighty-four subjects were examined within 36 hours of delivery and at 3 months. The rate of levator defects was 71.4% at early evaluation and 39.6% at late evaluation. Levator thickness and transverse hiatal diameters at rest and Valsalva were greater at late evaluation, while anteroposterior hiatal dimensions and hiatal area at rest and Valsalva were greater at early evaluation. There appeared to be an association between presence of levator defects and several maternal and fetal factors, including head circumference, fetal weight, and length of the first stage of labor.
COMMENTARY
The passage of the fetal head at time of vaginal delivery is associated with LA trauma. Prior studies using 3D perineal ultrasonography within 48 and 72 hours of delivery found LA avulsion rates of 19% and 40%, respectively. In MRI studies of the pelvic floor in women 9-12 months from delivery, 20% were found to have visible defects of the LA muscles. In a recent study, Van Delft evaluated primiparous women by endovaginal ultrasonography within 4 days of delivery; a quarter of women were found to have levator hematomas. Hematomas at the site of LA muscle attachment to the pubic bone always were predictive of LA muscle avulsion at 3 months.1
This study found a 71% rate of LA defects by ultrasonography within 36 hours of delivery and 40% at 3 months after delivery. Of the women with LA avulsions, 52% of the injuries persisted throughout the 3-month period. This study provides important information; however, direct comparisons between this and past studies is not appropriate because of differences in assessment times and imaging modalities. The use of 3D ultrasonography allows for dynamic assessment in real time. Additionally, one of the strengths of this study is the early assessment of the pelvic floor musculature that allowed for evaluation before remodeling occurs. The longitudinal follow-up employed in this study allowed for a better understanding of the dynamic changes in levator morphology and hiatal measurements in the postpartum period. Although prior data suggested that forceps delivery and prolonged second stage are risk factors for LA injuries, women with operative deliveries were excluded.
What does LA avulsion and trauma mean in the long-term? There is increasing evidence that vaginal birth increases a woman’s risk for developing pelvic organ prolapse and stress incontinence. However, the long latency between delivery and pelvic floor symptoms has made it difficult to study the clinical relevance of pelvic floor trauma at time of delivery. Studies looking at the association of levator muscle injury and stress incontinence have had conflicting results.2 However, there are data suggesting a relationship between levator injury and fecal incontinence.3 Studies strongly indicate the relationship between levator muscle injury and pelvic organ prolapse. In a case-controlled study comparing LA defects and pelvic floor function in women with and without prolapse, women with prolapse were much more likely to have major LA defects on MRI than controls (55% compared with 16%).4 In a retrospective, observational study comparing prolapse and levator avulsion imaging data of 781 subjects, prolapse was seen in 150/181 (83%) women with avulsion and in 265/600 (44%) women without avulsion, giving a relative risk of 1.9 (95% confidence interval, 1.7-2.1).5
This study further elucidates the effect of vaginal delivery on the pelvic floor. To date, there are few effective methods of preventing levator trauma. The use of forceps is a known risk factor for pelvic floor muscle trauma and use should be considered carefully. Perineal and pelvic floor muscle training during pregnancy may have an increasing role in prevention of pelvic floor disorders. Pelvic floor physical therapy after delivery plays a key part in the recovery from LA trauma and should be considered for all women undergoing vaginal delivery.
REFERENCES
- van Delft K, et al. Levator hematoma at the attachment zone as an early marker for levator ani muscle avulsion. Ultrasound Obstet Gynecol 2014;43:210-217.
- Schwertner-Tiepelmann N, et al. Obstetric levator ani muscle injuries: Current status. Ultrasound Obstet Gynecol 2012;39:372-383.
- Heilbrun ME, et al. Correlation between levator ani muscle injuries on magnetic resonance imaging and fecal incontinence, pelvic organ prolapse, and urinary incontinence in primiparous women. Am J Obstet Gynecol 2010;202:488.e1–6.
- DeLancey JO, et al. Comparison of levator ani muscle defects and function in women with and without pelvic organ prolapse. Obstet Gynecol 2007;109(2 Pt 1):295-302.
- Dietz HP, Lanzarone V. Levator trauma after vaginal delivery. Obstet Gynecol 2005;106:707-712.
Significant changes in levator muscles are visible by transperineal ultrasound in early and late postpartum period.
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