Objective To determine intrapartum risk factors associated with levator trauma as identified by ultrasound imaging.Design A prospective observational study. Population Nulliparous women (n = 488) in their first ongoing pregnancy.Methods An interview and four-dimensional translabial ultrasound was carried out between 36 and 38 weeks and again 3-4 months after delivery. Obstetric data were collected from the hospital database and/or participants' records. Main outcome measures Levator macrotrauma ('avulsion') and microtrauma (irreversible overdistension).Results A total of 367 women (75%) returned for the postpartum assessment after normal vaginal delivery (n = 187, 51%), vacuum (n = 34, 9%), forceps (n = 20, 5%) and caesarean section (n = 126, 34%). Median follow up was 4.08 months (interquartile range 3.68-5.03 months). Levator avulsion was diagnosed in 32 (13%) of the women who delivered vaginally and in none of the caesarean section group regardless of indication. On multivariable regression forceps delivery was significantly associated with avulsion (P = 0.01; OR 3.83; 95% CI 1.34-10.94). Using >20% peripartum increase in hiatal area on Valsalva as the cutoff, 28.5% of vaginally parous women were shown to have suffered irreversible overdistension. This was positively associated with the length of second stage (P = 0.001; OR 1.01 per minute; 95% CI 1.0-1.02). Intrapartum epidural appeared to have a protective effect (P = 0.03; OR 0.42; 95% CI 0.19-0.93).Conclusion Levator trauma at the time of first delivery is associated with vaginal delivery, forceps and a longer second stage. Epidural pain relief may exert a protective effect.

Objective To estimate the risk of prolapse associated with levator avulsion injury among a urogynaecological clinic population.Design Retrospective observational study.Setting Tertiary urogynaecological unit.Sample A total of 934 women seen for interview, examination using the pelvic organ prolapse quantification (POP-Q) staging system and imaging of the levator ani muscle by four-dimensional translabial ultrasound.Methods Retrospective review of charts and stored imaging data.Main outcome measures Pelvic organ prolapse stage II and higher and presence of defects of the levator ani muscle.Results After exclusion of 137 women with a history of antiincontinence or prolapse surgery, and a further exclusion of 16 women in whom either examination or imaging was impossible, we compared prolapse and imaging data in 781 women. Mean age was 53 years (range 15-89 years), and median parity was 2 (range 0-12). Women reported stress incontinence (76%), urge incontinence (69%), frequency (47%), nocturia (49%) and symptoms of prolapse (38%). Significant prolapse (stage II or higher) was diagnosed in 415 (53%) women, and 181 (23%) women were found to have levator avulsion defects. Prolapse was seen in 150/181 (83%) women with avulsion and in 265/600 (44%) women without avulsion, giving a relative risk (RR) of 1.9 (95% CI 1.7-2.1). The association was strongest for cystocele (RR 2.3, 95% CI 2.0-2.7) and uterine prolapse (RR 4.0, 95% CI 2.5-6.5).Conclusions Women with levator avulsion defects were about twice as likely to show pelvic organ prolapse of stage II or higher than those without. This effect is mainly due to an increased risk of cystocele and uterine prolapse.Keywords 3D ultrasound, avulsion, birth trauma, levator ani, pelvic floor ultrasound, pelvic organ prolapse.Please cite this paper as: Dietz H, Simpson J. Levator trauma is associated with pelvic organ prolapse. BJOG 2008;115:979-984.

Agreement between the two methods was moderate to substantial for all parameters except for hiatal area on Valsalva. Magnetic resonance imaging yielded higher area measurements on Valsalva, which may indicate difficulties in identifying the plane of minimal dimensions due to poorer temporal resolution compared with ultrasound imaging.