LONG TERM IMPLICATIONS OF SURGICAL LACERATION OF THE PERINEUM AND ANAL SPHINCTER

At least one generation of women in the United States is aging into the reality of having had the bulky, elastic core of their pelvic organ support system severely compromised by perineal laceration. Our mothers, damaged in just the same way, never became fully conscious of the connections between their hospital births and later hysterectomies, sphincterplasties, and incontinence procedures.

Primary pelvic organ support derives from the shape of the spine and the integrity of soft tissue connections to the skeletal frame. The pelvic diaphragm provides primary muscular support and is made up of a group of paired muscles that include the levator ani and coccygeus muscles. The levator ani are composed of horseshoe-shaped bands of muscle that span from pubic bone to coccyx. The inner most band is called the puborectalis, which surrounds the vagina and rectum like a sling. The puborectalis muscles maintain continence of solid stool by pulling sharply forward and creating an acute angle between the anus and rectum. This mechanism forces stool back up into the rectum where it is stored until evacuation.

Tough, membranous connective tissue surrounds the entire vaginal tube and is fused to the underside of the posterior vaginal wall. The rectovaginal fascia extends downward from the posterior aspect of the cervix and uterosacral ligaments to attach onto the upper margin of the perineal body. From there it extends laterally to blend with the fascia over the levator ani muscles. The uterosacral ligaments pull the vagina toward the sacrum, suspending it above the rectum.

The perineal body is located between the vaginal opening and anus. It is the attachment for the superficial muscles of the perineum, a portion of the levator ani, the external anal sphincter, and the rectovaginal fascia. Through its attachments to the uterosacral ligaments, the rectovaginal fascia stabilizes the perineal body, which is essentially suspended from the sacrum. The perineal body is further stabilized through indirect attachments to the pubic bones. In turn, the perineal body stabilizes all soft tissue structures of the pelvic interior. Its trampoline-like quality allows the pelvis to distend backward with sudden increases in intraabdominal pressure.

The combined internal and external anal sphincter complex maintains continence of flatus and liquid stool below the level of the puborectalis. The internal anal sphincter is a thickened continuation of the smooth muscle lining of the colon. Unlike the external anal sphincter and puborectalis muscles, the internal anal sphincter is not under voluntary control. The internal anal sphincter is responsible for most of the resting pressure of the anus. Therefore, continence at rest (particularly of liquid stool and flatus) is maintained by the internal sphincter. Continence during sudden rectal distension is provided by the external anal sphincter and puborectalis muscles.

A woman’s symptoms are often suggestive of what elements of the anal continence mechanism are not functioning properly. “For example, fecal urgency (defined as the inability to delay defecation) is a hallmark of injury to the external anal sphincter, whose primary responsibility is emergency control of impending leakage. Fecal soiling can occur with disruption of the external anal sphincter, hemorrhoids, or rectal prolapse. Incontinence to flatus and liquid stool is typically related to internal anal sphincter dysfunction or a rectovaginal fistula. Incontinence of solid stool is usually related to dysfunction of the puborectalis muscle and/or the external anal sphincter.”

Perineal lacerations from vagina to anus are graded according to depth. First-degree injuries include the skin and connective tissue; second-degree injuries cut into and through the perineal body; third-degree injuries extend into but not through the anal sphincter; and fourth-degree injuries go completely through the anal sphincter. By definition, an episiotomy makes a second-degree wound. Damage to the perineal body and anal sphincters results from the practice of episiotomy.

Throughout the history of obstetrics and gynecology the primary argument in favor of episiotomy was that it prevented genital prolapse and urinary incontinence. This framework came under careful scrutiny during the last decades of the 20th century and today it would be difficult to find a representative of medical science who seriously believes episiotomy prevents prolapse. Researchers now understand that destruction of the perineal body and alteration of the puborectalis muscles comprise the first pathophysiologic events in the development of pelvic organ prolapse.

While this has been a crucial step in the right direction, it has only halted or slowed down the rate of “routine” episiotomy. The injurious procedure is still being performed in hospitals throughout much of the developed world. I would argue that modern obstetrics could not exist independently of episiotomy because the cascade of obstetric interventions often necessitates enlarging the vaginal opening. Obstetric practice that anticipated the needs of the laboring woman without drugs or instrumentation would be midwifery.

Just as there has been much confusion and contradiction regarding the usefulness of episiotomy, the information existing in the medical literature on how best to manage old perineal lacerations is misleading at best. Perineorrhaphy is very commonly performed as part of “posterior repair”. The procedure attempts to reconstruct the perineal body by either pulling together the puborectalis muscles or reapproximating the more superficial muscles of the perineum. Surgeons describing the common results of this procedure tell us that “Most so-called levator stitches result only in increased approximation of thinned or separated layers of the perineal body and do not usually result in a buildup of the levator itself…if placed directly into the belly of the levator muscle, these sutures may actually destroy portions of the muscle, eventually resulting in a shelf-like ridge of nonelastic fibrous tissue within the introitus (vaginal opening) and immediately beneath the posterior vaginal wall.”

Many women believe their vagina to be “gaping” after episiotomy, but few understand either the reason for or long term implications of such an injury. “Any perineal laceration which permits the labia minora to retract laterally and expose a gaping vagina harbors the divided and retracted origin of the bulbocavernosus muscle. Such a lesion lowers the efficiency of the voluntary urethral sphincter and should be considered as an etiologic basis for stress incontinence in the female.”

Anal incontinence in the female almost always results from extension of a midline episiotomy into or through the sphincters. Researcher and childbirth educator Henci Gore tells us, “Without exception, the medical literature shows that anal injuries almost never occur except as extensions of an episiotomy.” Given that structural damage to the anal sphincters occurs in about one-third of women following hospital vaginal delivery and 50% of these will experience persistent problems, there are a staggering number of women alive today with symptoms of anal incontinence. These symptoms range from inability to control flatus to incontinence of solid and liquid stool.

Damage to the external anal sphincter is almost always anterior in location and results in a visible loss of the radial folds comprising the sphincter. In fourth degree lacerations, the perineum completely disappears and the vaginal and anal linings come into contact with each other. Women with third degree lacerations generally form a band of perineal scar tissue covering the top of the external anal sphincter. This results in the classic “dovetail” sign due to loss of the anterior radial folds in the sphincter.

Although anal sphincter repair operations are simple in concept, they are fraught with wound complication, tissue breakdown, and failure. Surgeons approach the repair by either approximating the severed muscles end to end or by overlapping them, the former having been generally replaced by the latter because of better outcomes. Reconstruction aims to restore continuity to the external and internal sphincters. However, “There is controversy among surgeons as to whether damage to the internal anal sphincter can be effectively repaired and function restored.”

Analysis of functional results following direct repair of the external anal sphincter reveals the percentage of women remaining incontinent of liquid and solid stool to be approximately 50%. “Correlation of the mechanism of sphincter injury with the functional outcome after repair reveals a diminished likelihood for rendering patients continent for liquid and solid stool after operative injury to the anal sphincter.” Women describe recovery from the operation as extremely painful and difficult. Because of the risk of fistula development from enclosed bacterial contamination, the wound is left open to heal and this requires a high level of post-operative care.

Due to the great degree of uncertainty accompanying these operations surgeons often counsel that not all individuals who are symptomatic require operative repair. “The decision to proceed with repair of anal sphincter injuries is in large measure determined by the extent of disability experienced by the patient. True fecal incontinence should be distinguished from urgency and seepage.” The following questions are helpful in making that distinction.

• Are you able to differentiate flatus from stool?

• Do you have incontinence of flatus only or of stool and flatus?

• Does stool escape from the anal canal or does seepage occur only at the time of a bout of diarrhea?

• Is the material that escapes from the anus truly feces or mucus secretion?

• Are you aware when stool escapes from the anal canal or does the presence of the stool go unnoticed for long periods of time?

• Do you have an urgency to evacuate and, if so, how long can you wait once the urge appears before the actual need to reach the bathroom?

• How much staining do you experience? Is it enough to require the use of a pad or do you have to wear some sort of absorbent underwear?

• “In patients in whom the diagnosis is in doubt, the ability to retain an enema argues strongly against any clinically significant incontinence.”

I would venture a guess that almost all women in the United States who gave birth in hospitals to at least two children before 1983 experience symptoms resulting from gross disruption of the perineum and loss of the ano-rectal angle. This sequela would include some or all of the following: vaginal prolapse, urinary incontinence, extremely thin tissues and little area between vagina and rectum, and for some percentage of women, varying degrees of fecal incontinence.

I would also suggest that the best way to address the damage is by supporting that area naturally through posture and lifestyle, and if necessary external support garments. A huge body of literature reflects extremely high morbidity and failure rates for all the prolapse surgeries, the sphincterplasties and the incontinence procedures.

Although it is very difficult to tell a young mother to live with the terrible rectal pressure that has resulted because her perineum is no longer elastic and distensible, the best person to tell her is the woman whose prolapse ultimately “required” a hysterectomy, four cystocele repairs, five rectocele repairs, a colostomy, colon resection, and more reconstruction of her perineum than she cares to remember.

“I must be careful each day to take just the right amount of bulking agent to control my fecal incontinence. It’s hit and miss so I make sure I’m always wearing adult protection. I manage the pain as best I can with low doses of valium, but when my rectum gets full I must immediately empty it or else my legs become numb.”

I leave the final words to Michel Odent, M.D:

“I have never had to repair the perineum after a real undisturbed foetus ejection reflex. One of the many reasons probably is that in such a context the mother is more often than not bending forward, for example, on hands and knees. In such postures, the mechanism of vulva opening is different from that of other postures. First the anterior part of the vulva opens more quickly; then the deflexion of the head tends to be delayed and, when the face is coming out, the chin is more lateral. I use this opportunity to mention that, if by chance there is a benign tear (usually because there has been no authentic foetus ejection reflex) I do not stitch it. If the mother does not spread her legs at all during the first two weeks (avoiding looking at the perineum, avoiding the lotus posture, etc) the cicatrisation will be perfect.”

Sources:

Dargent et al. Vaginal and Laparoscopic Vaginal Surgery 2004
Brubaker L Saclarides T The Female Pelvic Floor 1996
Rock J Thompson J TeLinde's Operative Gynecology 1997
Weber et al. Office Urogynecology 2004
Goer H A Thinking Woman's Guide to a Better Birth 1999
Nichols D Randall C Vaginal Surgery 1989
Benson Female Pelvic Floor Disorders 1992
Odent M The Caesarean 2004