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A perineal tear is a laceration of the skin and other soft tissue structures which, in women, separate the vagina from the anus. Perineal tears mainly occur in women as a result of vaginal
childbirth Childbirth, also known as labour, parturition and delivery, is the completion of pregnancy, where one or more Fetus, fetuses exits the Womb, internal environment of the mother via vaginal delivery or caesarean section and becomes a newborn to ...
, which strains the
perineum The perineum (: perineums or perinea) in placentalia, placental mammals is the space between the anus and the genitals. The human perineum is between the anus and scrotum in the male or between the anus and vulva in the female. The perineum is ...
. It is the most common form of obstetric injury. Tears vary widely in severity. The majority are superficial and may require no treatment, but severe tears can cause significant bleeding, long-term pain or dysfunction. A perineal tear is distinct from an
episiotomy Episiotomy, also known as perineotomy, is a surgical incision of the perineum and the posterior vaginal wall generally done by an obstetrician. This is usually performed during the second stage of labor to quickly enlarge the aperture, allowing ...
, in which the perineum is intentionally incised to facilitate delivery. Episiotomy, a very rapid birth, or large fetal size can lead to more severe tears which may require surgical intervention.


Anatomy

In women, an anatomical area known as the perineum separates the opening of the vagina from that of the anus. Each opening is surrounded by a wall, and the anal wall is separated from the vaginal wall by a mass of soft tissue including: * The muscles of the anus ( corrugator cutis ani, the
internal anal sphincter The internal anal sphincter, IAS, or sphincter ani internus is a ring of smooth muscle that surrounds about 2.5–4.0 cm of the anal canal. It is about 5 mm thick, and is formed by an aggregation of the smooth (involuntary) circular musc ...
and the
external anal sphincter The external anal sphincter (or sphincter ani externus) is an oval tube of skeletal muscle fibers. Distally, it is adherent to the skin surrounding the margin of the anus. It exhibits a resting state of tonical contraction and also contracts duri ...
) * The medial muscles of the urogenital region (the
superficial transverse perineal muscle The transverse perineal muscles (transversus perinei) are the superficial and the deep transverse perineal muscles. Superficial transverse perineal ...
, the
deep transverse perineal muscle The transverse perineal muscles (transversus perinei) are the superficial and the deep transverse perineal muscles. Superficial transverse perineal ...
and bulbocavernosus) * The medial
levator ani The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the ...
muscles (
puborectalis The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the ...
and
pubococcygeus The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the ...
) * The
fascia of perineum The fascia of perineum (deep perineal fascia, superficial investing fascia of perineum or Gallaudet fascia) is the fascia which covers the muscles of the superficial perineal pouch. The muscles surrounded by the deep perineal fascia are the bulbos ...
, which covers these muscles * The overlying
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...
and
subcutaneous tissue The subcutaneous tissue (), also called the hypodermis, hypoderm (), subcutis, or superficial fascia, is the lowermost layer of the integumentary system in vertebrates. The types of cells found in the layer are fibroblasts, adipose cells, and ma ...
A perineal tear may involve some or all of these structures, which normally aid in supporting the pelvic organs and maintaining faecal continence.


Classification

Tears are classified into four categories: *First-degree tear: laceration is limited to the fourchette and superficial perineal skin or vaginal
mucosa A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It ...
*Second-degree tear: laceration extends beyond fourchette, perineal skin and vaginal mucosa to perineal muscles and
fascia A fascia (; : fasciae or fascias; adjective fascial; ) is a generic term for macroscopic membranous bodily structures. Fasciae are classified as superficial, visceral or deep, and further designated according to their anatomical location. ...
, but not the anal sphincter *Third-degree tear: fourchette, perineal skin, vaginal mucosa, muscles, and anal sphincter are torn; third-degree tears may be further subdivided into three subcategories: **3a: partial tear of the external anal sphincter involving less than 50% thickness **3b: greater than 50% tear of the external anal sphincter **3c: internal sphincter is torn *Fourth-degree tear: fourchette, perineal skin, vaginal mucosa, muscles, anal sphincter, and rectal mucosa are torn *Button-hole tear: the tear involves rectal mucosa with an intact anal sphincter complex


Cause

In humans and some other primates, the head of the term fetus is so large in comparison to the size of the birth canal that delivery may result in some degree of trauma. As the head passes through the pelvis, the soft tissues are stretched and compressed. The risk of severe tear is greatly increased if the fetal head is oriented occiput posterior (face forward), if the mother has not given birth before or if the fetus is large. A surgical incision on the perineum skin called an
episiotomy Episiotomy, also known as perineotomy, is a surgical incision of the perineum and the posterior vaginal wall generally done by an obstetrician. This is usually performed during the second stage of labor to quickly enlarge the aperture, allowing ...
was historically used routinely in order to reduce perineal tears. However, its routine use has declined as there is some evidence it increases the severity of tears when it is not indicated. A Cochrane review found that routine use of episiotomy increased the incidence of severe perineal tears by 30%. Several other techniques are used to reduce the risk of tearing, but with little evidence for efficacy. Antenatal digital perineal massage is often advocated, and may reduce the risk of trauma only in nulliparous women. Hands-on techniques employed by midwives, in which the foetal head is guided through the vagina at a controlled rate have been widely advocated, but their efficacy is unclear.
Water birth Water birth is childbirth that occurs in water, usually a birthing pool. It may include the use of water for relaxation and pain relief during the first stage of labour, birth into water in the second stage of labour, and the delivery of the pla ...
and labouring in water are popular for several reasons, and it has been suggested that by softening the perineum they might reduce the rate of tearing. However, this effect has never been clearly demonstrated.


Prevention and treatment

Perineal protection is an obstetric measure to prevent the perineal tissue from tearing (perineal tear) during the birth of the baby's head or to keep the extent of the injury as small as possible. The midwife (or obstetrician) supports the perineal tissue with one hand as soon as the head stretches. The other hand rests on the baby's head and regulates its speed of passage (so-called head brake). At the same time, the woman giving birth is guided to push along slowly and in a well-dosed manner. This allows the head to be born slowly over the perineum, which thus has enough time to stretch. Warm compresses held against the perineum during the second stage of labor can reduce the risk of tearing. Treatment is to either let the tear heal naturally or to surgically repair it. Third- and fourth-degree tears generally require surgical repair. A
Cochrane review Cochrane is a British international charitable organisation formed to synthesize medical research findings to facilitate evidence-based choices about health interventions involving health professionals, patients and policy makers. It includes ...
of comparing surgical treatment with natural healing of first- and second-degree tears found no to little difference between the two treatment options. The review concluded that there was insufficient evidence to recommend either treatment option over the other for first- and second-degree tears.


Prevalence

A 2008 study found that over 85% of women having a vaginal birth sustain some form of perineal trauma. A retrospective study of 8,603 vaginal deliveries in 1994 found a third-degree tear had been clinically diagnosed in only 50 women (0.6%). However, when the same authors used anal
endosonography Endoscopic ultrasound (EUS) or echo-endoscopy is a medical procedure in which endoscopy (insertion of a probe into a hollow organ) is combined with ultrasound to obtain images of the internal organs in the chest, abdomen and colon. It can be used ...
in a consecutive group of 202 deliveries, there was evidence of third-degree tears in 35% of first-time mothers and 44% of mothers with previous children. These numbers are confirmed by other researchers in 1999. A study by the
Agency for Healthcare Research and Quality The Agency for Healthcare Research and Quality (AHRQ; pronounced "ark" by initiates and often "A-H-R-Q" by the public) is one of twelve agencies within the U.S. Department of Health and Human Services (HHS). The agency is headquartered in North ...
(AHRQ) found that in 2011, first- and second-degree perineal tear was the most common complicating condition for vaginal deliveries in the U.S. among women covered by either private insurance or Medicaid. Second-degree perineal laceration rates were higher for women covered by private insurance than for women covered by Medicaid.<


Complications

First- and second-degree tears rarely cause long-term problems. Among women who experience a third- or fourth-degree tear, 60–80% are asymptomatic after 12 months. Faecal incontinence, faecal urgency, chronic perineal pain, pain with sex, and fistula formation occur in a minority of women, but may be permanent. The symptoms associated with perineal tear are not always due to the tear itself, since there are often other injuries, such as avulsion of pelvic floor muscles, that are not evident on examination. There are claims that sometimes the perineum is excessively repaired after childbirth using a so-called " husband stitch" and that this can increase vaginal tightness or result in pain during intercourse.


References


External links

{{Authority control Obstetrics Midwifery