This document was published more than 2 years ago. The nature of the evidence may have changed.
Childbirth is usually free of complication for both mother and child, although minor tears in the mother’s perineum are not unusual. This report focuses on the most severe form of perineal injuries: anal sphincter tears. Such injuries are most often detected during a clinical exam. How the exam is carried out differs between clinics, as well as between examiners. Approximately 3.5% of women who deliver vaginally in Sweden are diagnosed with anal sphincter injuries that, if left untreated, could lead to the woman losing control of her bowels and lead to suffering. Risk factors associated with anal sphincter injuries include first time delivery, assisted vaginal delivery with vacuum or forceps, delivering a large baby, delivering a baby that presents abnormally (i.e. if the top of the baby’s head does not descend into the birth canal first), or if the mother has been circumcised.
The Swedish agency for health technology assessment and assessment of social services (SBU) was tasked by the Swedish Government to audit and assess the available information regarding methods that reduce complications and injuries to women giving birth.
The aims of this systematic assessment were to investigate:
A thorough examination of the mother immediately after she has given birth is critical in the detection of tears in the genital region. The quality of postnatal examination methods varies, and some tears are missed. The scientific literature rarely describes exactly how immediate postnatal exams are performed. This report shows that endoanal or vaginal ultrasound examinations can uncover anal sphincter injuries in approximately 9% of women who were given standard postnatal exams immediately after giving birth vaginally. A similar proportion of anal sphincter injuries are detected when either vaginal or transperineal ultrasound is used to examine women well after they have given birth. Anal incontinence is significantly more common in women who are not examined with endoanal ultrasound, indicating that improved diagnostics could lead to less suffering. Endoanal ultrasound is an established objective and sensitive method that can be documented. Providing this diagnostic service, around the clock, at all of Sweden’s 46 clinics would require a large investment in both equipment and training for health care staff. The development of more accessible routine methods for preventing birthing injuries could be an alternative solution.
This SBU report shows that there is scientific evidence indicating that the risks of sustaining an anal sphincter injury is lower when an episiotomy is performed prior to vacuum assisting a delivery for women giving birth for the first time who have a low to moderate risk of anal sphincter injury. Applying vacuum assistance is a risk factor, and the protective effect of an episiotomy is cancelled out when more than three additional risk factors exist, such as if the infant is big, if the pushing phase is long, or if the woman is advanced in age or has previously had an anal sphincter injury. To prevent an anal sphincter injury to one women, episiotomies would need to be performed on approximately twelve women. An episiotomy can be considered a grade two injury to the perineum and vaginal wall that is caused by health care providers. The injury from an episiotomy will require suturing so that all of the muscle attachments are reconstructed. What is more, women with anal sphincter injuries that are found and sutured correctly rarely develop any negative symptoms. The balance between risk and benefit for episiotomies is therefore not entirely straightforward, and depends heavily on the reliability of the diagnostic methods used to detect anal sphincter injuries. An episiotomy may be unavoidable if the baby needs to be delivered quickly. However, the routine use of episiotomies for vaginal births to protect the mother from anal sphincter injuries is not supported by the scientific evidence presented in this report, nor is it recommended by WHO.
Staff training initiatives conducted in countries neighbouring Sweden incorporated multiple components whose effectiveness were not independently assessed. It was suggested that manually protecting the perineal region was an important component despite this technique never having been studied independently in randomised controlled studies. The rate of episiotomies increased after these staff training initiatives. It was not clear whether this increase in episiotomies was specifically linked to vacuum assisted deliveries involving women who were giving birth for the first time. There is a risk that focusing on prevention could result in injuries being underreported, as staff will receive positive feedback when it is perceived that they have prevented tearing. The lack of objective diagnostics regarding anal sphincter tearing means the results should be interpreted with caution. It is believed that applying warm compresses to the perineal region can prevent anal sphincter injuries. However, it is not possible to determine if the warm compresses are responsible for the effect, or if it is due to the mechanical protection of the perineum the method affords.
During childbirth, there are two individuals with basically the same human dignity that must be given consideration, the mother and the infant. Occasionally a decision must be made to cause harm to one of the individuals to prevent harm to the other. For instance, by accelerating delivery with vacuum assistance, forceps or episiotomy when there is an imminent risk that the baby is not getting enough oxygen could inflict an injury on the mother that will result in a lifelong handicap. There is always an ethical dilemma, even when the decision is medically motivated; how big does the risk to the child need to be to motivate performing a procedure which will increase the mother’s risks of being injured?
We have identified the following evidence gaps regarding the diagnostics for and prevention of anal sphincter injuries:
presents a comprehensive, systematic assessment of available scientific evidence. The certainty of the evidence for each finding is systematically reviewed and graded. Full assessments include economic, social, and ethical impact analyses.
SBU assessments are performed by a team of leading professional practitioners and academics, patient/user representatives and SBU staff. Prior to approval and publication, assessments are reviewed by independent experts, SBU’s Scientific Advisory Committees and Board of Directors.