Prediction and prevention of perineal and pelvic floor trauma

Elective caesarean delivery is the only true primary prevention strategy. Caesarean delivery after the onset of labour is not pro­tective of pelvic floor trauma. The surgical and anaesthetic risks of caesarean section(s) for future pregnancies need to be considered in making an informed decision.

An increased risk of long-term urinary incontinence (141) and surgery for POP and/or stress urinary incontinence (60) following vaginal delivery has been well documented. Caesarean delivery, elective or emergency, seems to provide only partial protection. Eight or nine caesarean sections would need to be performed to avoid one case of urinary incontinence (141).

With regards to POP, women delivered exclusively by caesarean section have a significantly reduced risk of POP in the long term. In a 12-year longitudinal study, women who had all births by cae­sarean section were the least likely to have prolapse compared with women whose births were all spontaneous vaginal deliveries (OR 0.11; 95% CI 0.03-0.38) (142). As the lifetime risk of undergoing a single operation for POP and urinary incontinence is only 11.1% (143), elective caesarean delivery for prevention of pelvic floor dis­orders could potentially cause other morbidities to women who would have been delivered vaginally and not have any pelvic floor problems.

Antenatal pelvic floor muscle training

Antenatal pelvic floor muscle training has been shown to reduce the incidence of postnatal stress urinary incontinence in the short term (144-146) but not in the long term (147, 148).

Warm compresses and perineal massage

Antenatal perineal massage can prevent perineal trauma and peri­neal pain (149). Women practising perineal massage antenatally are less likely to have an episiotomy.

A Cochrane review concluded there is a significant effect of warm compresses and perineal massage during the second stage of labour on reduction of perineal trauma and suturing (150).

Maternal position during delivery

A Cochrane review highlighted possible benefits with upright pos­ition in women without epidural anaesthesia, including a very small reduction in the duration of the second stage of labour mainly in primigravid women, and reduction in episiotomy rates and assisted deliveries; however, the authors commented on a possibly increased risk of second-degree tears (151).

A population-based study concluded that the lateral position has a slightly protective effect compared with the sitting position in nulliparous women. An increased risk of OASIS was noted among women in the lithotomy position, irrespective of parity. Squatting and birth seat position were associated with an increased risk among parous women (88).

Instrumental delivery

Women delivered by forceps had more anal sphincter injuries than those delivered by vacuum (74). Compared to vacuum delivery, use of forceps was associated with almost twice the risk of developing faecal incontinence (152).

Perineal support at delivery

A study from Finland suggested that the lower OASIS rate (0.6%) observed there, was a result of the use of perineal support and episi­otomy, compared with other Nordic countries (OASIS rates 3.6­4.2%) (153). In Norway, implementation of the ‘hands-on’ method resulted in a 50% reduction in OASIS rates (34, 154), recommending the use of perineal support as a method of prevention.

Pushing during the second stage

A prolonged second stage with strong voluntary pushes has been implicated in denervation injury (17). A review by Barasinski et al. concluded that the low methodological quality of the studies and the differences between the protocols do not justify a recommen­dation of a particular pushing technique (155). A Cochrane review of included studies of moderate to low quality suggested that de­layed pushing leads to a shortening of the actual time pushing and increase of spontaneous vaginal delivery at the expense of an overall longer duration of the second stage of labour.

In conclusion, elective caesarean delivery before labour is the only true primary prevention intervention for pelvic floor trauma, but the impact of pregnancy itself on the pelvic floor as well as the risks of a caesarean delivery should be explained and considered during the counselling process. Alternative primary prevention interven­tions include antenatal pelvic floor exercises and perineal massage. Modifications of obstetric practices such as restrictive use of episi­otomy, mediolateral episiotomy when necessary, spontaneous over forceps delivery, vacuum over forceps delivery, and perineal mas­sage in the second stage of labour may result in prevention of pelvic floor trauma. Finally, the choice of mode of delivery in women with previous severe perineal trauma and pelvic floor morbidities may have an impact on risks of recurrence of severe perineal trauma and exposure to or prevention of long-term pelvic floor sequelae. Although the risk of recurrent OASIS is still either similar to the risk of primary OASIS according to Boggs et al. (5.3%) (157) or increased fivefold (7.2%) according to another study (158), a Cochrane review concluded that the effectiveness of interventions for women in sub­sequent pregnancies following obstetric anal sphincter injury is un­known (159). Jango et al. recommend that women opting for vaginal delivery after obstetric anal sphincter injury should be informed about the risk of recurrence, which is associated with an increased risk of long-term flatal and faecal incontinence (160). Women with a history of an obstetric anal sphincter injury who are symptomatic or have abnormal endoanal ultrasonography and/or manometry should be offered the option of elective caesarean birth.