Intrapartum risk factors for levator trauma

Abstract

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.

Levator ani muscle avulsion during childbirth: a risk prediction model

“…5 However, the definition they used was 'a loss of continuity between muscle and pelvic side wall in all volume data sets (rest, squeeze, Valsalva)', 5 which is different from a more recent suggested definition in which TUI at maximum pelvic floor muscle contraction is used to diagnose LAM avulsion. 21 This might explain why later studies [7][8][9][10][11] using the same definition on TPUS as in our study, have found similar incidence rates of LAM avulsion. This highlights the importance of using standardising terms when research is conducted.…”

“…Nevertheless, OASIS, prolonged second stage of labour and forceps delivery will certainly put women at a high risk of LAM avulsion, which is in keeping with the literature. 6,8,10,14 It has been suggested that prediction models should only be presented when they can be clinically applicable. 24 We therefore developed clinically applicable nomograms based on our risk model, to estimate a woman's individual risk of having sustained LAM avulsion, which can be used in a clinical setting.…”

“…3 This avulsion occurs in 13-36% of women mainly during the first vaginal delivery [4][5][6][7][8][9][10][11] by stretching and tearing of the muscle from the insertion on the inferior pubic ramus. 12 A variety of childbirth-related risk factors for LAM avulsion have been described in the literature, 13 including operative vaginal delivery, 11 forceps delivery, 6,10,14 OASIS, 6 episiotomy, 6 prolonged second stage of labour, 6,8,10 increased fetal head circumference 8 and increased maternal age. 6 On the other hand, epidural analgesia is thought to be a protective factor.…”

“…6 On the other hand, epidural analgesia is thought to be a protective factor. 10 In a prospective study, Shek and Dietz aimed to describe antepartum predictors of major LAM avulsion. 9 They found that a lower body mass index (28 versus 30 kg/m 2 ) was the only significant risk factor 9 and were therefore unable to develop an antepartum prediction model.…”

Imaging in patients with obstructed defecation

“…We now know that the levator ani is commonly damaged in childbirth [5,6], that the use of forceps is the main risk factor [7], and that such tears and overdistension lead to excessive distensibility of the levator hiatus, the largest potential site for herniation in the human body [8]. This damage is associated with symptoms and signs of female pelvic organ prolapse [8,9], with rectal intussusception [10] and with prolapse recurrence after pelvic reconstructive surgery [11][12][13].…”