Intrapartum risk factors for levator trauma

Abstract

Please cite this paper as: Shek K, Dietz H. Intrapartum risk factors for levator trauma. BJOG 2010;117:1485–1492. Objective To determine intrapartum risk factors associated with levator trauma as identified by ultrasound imaging. Design A prospective observational study. Setting Antenatal clinic of a tertiary hospital between May 2005 and February 2008. 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.