The use of epidurals may help prevent future pelvic organ prolapse

A new study to be published in BJOG shows how the use of epidurals during birth may have a protective effect on the levator ani muscles, which hold up the pelvic floor.

The levator ani muscle is found in the pelvis attached to its sidewalls and forming a platform holding up the internal organs; in women this includes the uterus. Tearing of this muscle (levator avulsion) during childbirth has been found in 15-35% of women who have given birth vaginally, and has been shown to be a strong risk factor for pelvic organ prolapse (POP).

Researchers from Australia undertook a prospective study of 488 women undergoing their first pregnancy between May 2005 and February 2008. The object of the study was to determine if there are any risk factors during birth which may result in levator trauma including macrotrauma (large scale avulsion – tearing) and microtrauma (damage to the muscle tissues such as irreversible overdistention of the pelvic floor opening). Researchers believed that the findings from their study may help modify obstetric practice to help prevent levator injury.

All participants had an uncomplicated, singleton pregnancy; were over 18 years of age and between 34 and 36 weeks of gestation. They were all aiming for a vaginal birth. The women were interviewed and underwent an ultrasound scan. A second appointment occurred 3-4 months after delivery and the ultrasound assessment was repeated. Mode of delivery was recorded.

No levator avulsion was recorded in the women who had a caesarean section. Levator avulsion was diagnosed in 13% of women who had a vaginal birth (9% of whom had had a vacuum delivery and 35% of whom had had a forceps delivery). Researchers found that forceps delivery was associated with a three to four-fold increase in levator avulsion. Postbirth assessment showed that the longer the 2nd stage of labour, the higher the likelihood of microtrauma. Women who had an intrapartum epidural were found to have had a lower incidence of microtrauma. The researchers suggest that epidurals, because they relax the muscles through paralysis, may be beneficial in preventing levator trauma.

Dr Clara Shek, co-author of the study from the Nepean Clinical School of Medicine at the University of Sydney said “Injury to the levator ani muscle may be the missing link between childbirth and pelvic organ prolapse. Identification of intrapartum factors associated with levator injury may allow us to adjust obstetric practice in order to reduce the future prevalence of pelvic organ prolapse.

“In our observational study, forceps delivery was found to be associated with levator avulsion (‘macrotrauma’). Length of the second stage was associated with irreversible overdistension of the levator hiatus (‘levator microtrauma’). Intrapartum epidural anaesthesia seems to have a protective effect against levator microtrauma.”

BJOG editor-in-chief, Professor Philip Steer said, “There will be occasions when the use of forceps to help deliver the baby is appropriate. This research shows the effects of forceps delivery are not without risk so it is important to ensure that all our trainees receive good training in carrying these out and existing doctors keep up-to-date with their skills so that levator trauma is minimised.

“Likewise, the finding that epidurals may provide a protective effect by reducing levator damage is reassuring. The short-term priority is to reduce pain during childbirth but the longer term effect of reducing muscle damage and prolapse is welcome.” 
 

The full study: Shek K, Dietz H. Intrapartum risk factors for levator trauma. BJOG 2010;117:1485–1492. DOI: 10.1111/j.1471-0528.2010.02704.x.
 

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