Vaginal tears in childbirth are something that worries a lot of women during their pregnancy. However, it seems that the different severities of tears is confusing to many people. There are differences between a 1st degree and 4th degree tear. Not all women know which degree of vaginal tear they suffered. Read on to try and untangle the differences between the different degrees of tears.

Basic Anatomy

First things first. Vaginal tears are actually called perineal tears. The perineum is the area between the vaginal opening and the rectum. Not all tears are in the actual vagina, and so the term perineal tear is a bit more accurate. Moving from the vaginal opening to the rectum you have the following layers:

  • Perineal Skin – This is the skin right at the vaginal opening. It has blood vessels and nerves, but no muscle fibers here.
  • Pelvic Floor (Levator Ani) Muscles – These are the muscles that start at the pubic bone and travel to the tailbone. They have sections that loop around the vagina and the rectum, but it’s the part that loops around the vaginal opening (between the back of the vagina and the front of the rectum) that is usually affected by perineal tears during birth.
  • Anal Sphincter – This is a circular muscle that goes around the anus. When it activates, it contracts and tightens, closing the anal opening. This is a good thing – trust us.
  • Rectal Mucosa – This is the mucosal lining, or membrane, and is what lines the rectum. And just to be clear, the rectum is the tube that attaches the descending colon to the anus.

perineal anatomy png scaled

Perineal Anatomy – Intact pelvic floor with perineal skin (bright pink), pelvic floor muscles (rose colour), anal sphincter (red), and rectal mucosa in the centre of the sphincter.

Perineal Tears

Vaginal tears that occur in childbirth are differentiated by severity. Let’s examine the difference between the four categories of perineal tears.

First degree tear:

This is a tear that occurs only in the perineal skin. Often times it doesn’t require stitches. You can have more than one of any tears, including these smaller first degree tears. First degree tears tend to heal quite quickly without much help needed. Even though first degree tears are the least invasive tear, women can still experience pelvic floor symptoms like pain, leaks and vaginal heaviness.

1st degree tear

1st Degree Tear – vaginal tear into the perineal skin (light pink colour).

2nd Degree Tear

A second degree perineal tear is through the perineal skin, and into the pelvic floor muscles. These tears can extend deeper into the vagina. Physicians usually use stitches, or sutures, to repair second degree perineal tears, and they take a bit longer to heal than first degree tears.

2nd degree tear

2nd Degree Tear – Extends through the perineal skin and into the pelvic floor muscles (light pink and rose colours).

3rd Degree Tear

A third degree perineal tear extends through the perineal skin and pelvic floor muscles, and into the anal sphincter muscle. These repairs typically take a bit longer than second degree tears. Because the anal sphincter is injured during a third degree tear, women can experience gas and fecal incontinence. However, as with fourth degree tears (read below), there is lots to be done to help if you do experience anal incontinence symptoms. Third degree tears can be further subdivided into 3A and 3B tears. A 3A tear is where the tear extends into the first 50% of external anal sphincter muscle fibers, whereas a 3B tear extends into the deeper 50% of the external anal sphincter muscles fibers.

3rd degree tear

3rd Degree Tear – Extends through the perineal skin, the pelvic floor muscles and into the muscles of the anal sphincter (light pink, rose and red colours).

4th Degree Tear

These tears extend through the perineal skin, pelvic floor muscles, anal sphincter and into the rectal mucosa. They extend into the rectum. Fourth degree tears are often repaired in the operating room with anesthesia.  It is important to repair the anal sphincter well, to limit the risk of anal incontinence (leaking gas or feces). Many physicians will monitor 4th degree tears closely. They try to make sure that anal sphincter function returns, and decide if more testing or more procedures are necessary to help it function properly. Because both 3rd degree and 4th degree tears affect the anal sphincter muscle, they are sometimes called OASIS (Obstetrical Anal Sphincter Injuries).

I am happy to report that our local physicians (we’re on the east coast of Canada) typically refer to pelvic floor physiotherapists almost immediately after discharge from the hospital when women suffer an OASIS. At this time a pelvic floor vaginal/rectal exam is not possible. Instead, women are taught (from the outside) how to contract their pelvic floor muscles and their anal sphincter (yes there is a difference), and to help rehabilitate the return of anal sphincter and pelvic floor muscle function.

4th degree tear

Fourth degree tear – extends through the skin, pelvic floor and anal sphincter muscles into the rectum.

Well Done

Now you have a pretty solid understanding of the four different severities of vaginal tears that can occur in childbirth. Stay tuned for more information about what control you might have in preventing high degree vaginal tears and how to recover from a vaginal tear. If you think that you are suffering from symptoms resulting from a perineal tear, please talk to your primary care physician, gynecologist, or pelvic floor physiotherapist.

Hope this helps!

Katie Kelly, PT & Eryn Matheson, PT

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