Not polite cocktail conversation (yet): obstetric anal sphincter injury

     Abraham (Nick) Morse is the Vice Director of Urogynecology at Guangzhou Women and Childrens Medical Center. He specializes in gynecology and obstetrics, healthcare delivery in China, clinical research and health care quality and safety. He is a graduate of Harvard Medical School and has been practicing for 19 years. Below is a blog he has written about an injury that occurs during delivery that can greatly affect women afterwards, and is not discussed, or even known much about, by the general public.

     Human birth is an amazing and beautiful process which most of the time is best allowed to proceed naturally and without significant medical intervention. However, a small proportion of pregnancies and deliveries can evolve very quickly into a life-threatening emergency for the mother, baby, or both – sometimes without risk factors or warnings. While the focus is appropriately on preventing death, it is also important to remember that mother and baby can sustain injuries during childbirth that will affect them for the rest of their lives.

     One injury that can occur during vaginal childbirth that all too frequently affects a woman profoundly for the rest of their lives is injury to the anal sphincter complex. Sometimes there can be tears of the vagina, pelvic muscles and connective tissue during vaginal delivery. Most of the time these tears heal quickly with the help of suturing by a birth attendant. However, in somewhere between 1% and 5% of deliveries, the tear of the perineal tissue extends into the anal sphincter and even lower rectum. These are among the most serious childbirth injuries for the mother; and although significant improvements have been made to reduce the incidence of these devastating injuries, (for instance by not performing routine episiotomy for births that do not involve the use of forceps or vacuum assistance), they will probably never be completely preventable.

     Although it is not something that polite people talk about at cocktail parties, the anal sphincter is a truly remarkable structure that is dependent on the coordination of several interconnected muscle bundles based on sensory signals from two separate nervous systems to allow us to control the release of gas and stool from our rectum. Because of the high level of subtle function that is required, when this area is damaged, it requires time, adequate resources, and a high level of expertise to repair in such a way that maximizes the chances for long-term recovery of continence of both gas and feces. These resources can be difficult to mobilize in the midst of a busy labor and delivery – often in the middle of the night.

     Unfortunately, we know that our ability to diagnose and repair anal sphincter injuries still has much room for improvement. One study in England found that more than 50% of anal sphincter injuries were not even diagnosed at the time of delivery. Another study using advanced imaging showed that 1/3 of anal sphincter repairs had already failed three months after delivery and that these failures were associated with a higher likelihood of persistent problems with bowel control. We know from other reports that the functional outcomes in the medium to long term are not where we would like them to be. One study documented that two years after delivery, 50% of women who suffer an anal sphincter injury still had fecal incontinence at least once a week. A different study from Sweden found that ¾ women still had some fecal incontinence five years after delivery that involved an anal sphincter injury.

     However, there is some good news. Recently a large clinical trial that introduced a “bundle” of interventions to try to reduce the rate of anal sphincter injury reduced the incidence from 4.6% to 1.8% in less than a year.

     In summary, anal sphincter injuries can be devastating with no guarantee of good long-term outcomes, even when they are diagnosed and repaired by experienced obstetric caregivers.

     Despite all of the appropriate attention to trying to reduce C-section rates in many developed and developing countries, if a woman appears to be at very high risk for sustaining an anal sphincter injury (for example a woman with diabetes during pregnancy where an ultrasound predicts a large baby), and labor is not progressing easily, consideration of C-section to avoid this outcome is not unreasonable.

Photo © United Nations 2019: UN Photo/Evan Schneider

Scenes from Ifo 2 Refugee Camp in Dadaab, Kenya
A new mother watches over her child at the Ifo 2 Refugee Camp Hospital in Dadaab, Kenya, which is supported by the United Nations High Commissioner for Refugees (UNHCR). Secretary-General Ban Ki-moon visited the hospital as part of his visit to the camp this afternoon.
29 October 2014
Dadaab, Kenya
Photo # 609544