Hands-on or hands-off the perineum at childbirth: A re-appraisal of the available evidence

Abstract

Obstetric anal sphincter injuries (OASIS), or third-degree and fourth-degree perineal tears, represent a serious complication of vaginal birth. There are reports that OASIS is a risk factor for the development of anal incontinence [1][2][3][4] , with significantly worse bowel symptoms and anorectal function with the higher degree of OASIS 5,6 . In addition, the economic cost of anal incontinence management following OASIS has been estimated to be approximately £1625 per patient 7 or £78 million per annum in the United Kingdom alone 8 . The current UK based maternity practice at second stage of labour involves two techniques 9,10 : 1) 'hands-on', where one hand of the practitioner applies pressure on the fetal head while the other hand supports the perineum, 2) 'hands-poised', where the hands of the practitioner are poised, ready to apply light pressure on the fetal head to avoid rapid expulsion. Most often, however, this latter technique has been misinterpreted as a 'hands-off technique'.The Royal College of Midwives (RCM) in 2012, and in line with the NICE 2007 guidance on intrapartum care, has suggested that the available evidence is inconclusive as to whether the 'hands-on' technique reduces the incidence of severe perineal trauma , which have however received heavy criticism from later studies as to the validity of their results and the robustness of their study design and methodology 14,15 . In the United Kingdom the incidence of OASIS for primiparous women has been reported to have tripled from 1.8% to 5.9%, over a 12-year period 8 . In Norway, the OASIS rate has increased from <1% in the 1960s to 4.3% at the beginning of the past decade 16,17 . A similar increase has been noted in other European countries, with the exception of Finland where the OASIS rate has remained stable at less than 1% over the past 25 years 18,19 . It is considered that this increase is secondary to the increased incidence of instrumental deliveries, improved training for health professionals and changing maternal-fetal risk factors. Nevertheless, regardless of the above-mentioned factors, the low risk of OASIS in Finland is suggested to be due to the classic 'hands-on' technique of perineal support at birth 19,20 . This hypothesis was tested in Norway in two hospital-based studies (2010 and 2012) that showed a significant decrease of OASIS by 50-70% 1,16 . It is interesting that these two studies were commissioned by the Norwegian Board of Health in 2004 as part of the national strategy to reduce OASIS, since hospitals were heavily criticised for having a high OASIS rate of 4.5% in 2004, and were therefore required to implement programs to reduce this.Following these two studies 1,16 , there was a UK population-based study in 2016 that replicated the study design of the Norwegian studies 21 . This UK study showed that 'hands-on' the perineum during the crowning at second stage reduced the OASIS overall rates by 23% and the 3c third degree and 4th degree tears by 71%. In a recent metanalysis in 2015 of observational studies, ...