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Clinical 15:321–334 (2002)

REVIEW

Anatomy and Physiology of the Female Perineal Body With Relevance to Obstetrical Injury and Repair

1 2 PATRICK J. WOODMAN * AND DANIEL O. GRANEY 1Department of Obstetrics and Gynecology, Madigan Army Medical Center, Tacoma, Washington 2Department of Biological Structure, University of Washington School of Medicine, Seattle, Washington

The female perineal body is a mass of interlocking muscular, fascial, and fibrous components lying between the and anorectum. The perineal body is also an integral attachment point for components of the urinary and fecal continence mechanisms, which are commonly damaged during vaginal . Repair of injuries to the perineal body caused by spontaneous tears or are topics too often neglected in medical education. This review presents the anatomy and physiology of the female perineal body, as well as clinical considerations for pelvic reconstructive surgery. Clin. Anat. 15:321–334, 2002. © 2002 Wiley-Liss, Inc.

Key words: perineal body; central tendon; ; episiotomy; incontinence; episiorrhaphy

INTRODUCTION CLASSIC ANATOMY

“I learned how to repair a fourth-degree (episi- MacAlister first named the perineal body in 1889 otomy) long before I learned how to protect the (Oh and Kark, 1973). It marks the embryologic site of perineum…” fusion between the anal tubercles and the pelvic bar, -Quote froma second-year Ob-Gyn resident which separate the cloacal sphincter into anal and urogenital portions. The urorectal septumgrows cau- Ironically, the perineal body is commonly damaged, dally until it reaches the , dividing but poorly repaired, due in large part to suboptimal the into two parts: an anterior knowledge of its anatomy (Sultan et al., 1995). Other and a posterior anorectum(DeLancey, 1989). The factors contributing to poor repair include time pres- urorectal septumbecomesthe perineal body in the sures of a busy clinical schedule, fatigue, inadequate adult. analgesia, or inexperience (Sultan et al., 1995). A poor The perineal body is the central point between the episiorrhaphy can cause pain, dyspareunia (painful urogenital and anal triangles of the perineum. Its intercourse), aerovagina (air trapping within the three-dimensional form has been likened to that of vagina), pelvic organ prolapse froma gaping introitus, the cone of the red pine (Pinus resinosa, Fig. 1) with and fecal or urinary urgency or incontinence. each “petal” representing an interlocking structure, The perineal body is a complex fibromuscular mass into which many structures insert. It is bordered ceph- alad by the rectovaginal septum(Denonvilliers’ fas- The opinions and assertions contained herein are the private views of the authors and are not to be construed as official or reflecting cia), caudad by the perineal , anteriorly by the the views of the Department of the Army or the Department of posterior wall of the vagina, posteriorly by the anterior Defense. wall of the anorectum, and laterally by the ischial rami. *Correspondence to: MAJ Patrick J. Woodman, MC, USA, 115 What follows is a description of the formand function Colorado Ct., Southern Pines, NC 28387. of the female perineal body. E-mail: [email protected] has been used to standardize anatomical nomencla- Received 28 July 2000; Revised 2 August 2000, 7 January 2002 ture (Federative Committee on Anatomical Terminol- Published online in Wiley InterScience (www.interscience.wiley. ogy, 1998). com). DOI 10.1002/ca.10034

© 2002 Wiley-Liss, Inc. 322 Woodman and Graney

omy of the as a triple-loop system of muscle bundles for both males and females. The deep part of the external anal sphincter and a reflection of the (puborectalis) formthe top loop, and the subcutaneous part of the external anal sphincter forms the bottom loop, both of which attach anteriorly to the perineal body; the superficial part of the external anal sphincter, which forms the middle loop, is tethered posteriorly to the . Shafik’s work modernized the understanding of the anal con- Fig. 1. The flowering pattern of Pinus resinosa. tinence mechanism. Anteriorly, the perineal body is firmly adhered to the vaginal muscularis submucosa (DeLancey, 1992). such as an insertion site of or a muscle of the perineum. Pelvic musculo-tendinous and fibrous fas- It is suspended anteriorly to the pubic bone by the cial attachments to the perineal body show a similar puborectalis and pubovaginalis. The perineal body is pattern (Fig. 2). also connected anteriorly to the posterior border of the The perineal body is devoid of subcuticular fatty perineal membrane (Wilson, 1967). Laterally, the per- tissue. Upon removal of the fatty tissue in the adjacent ineal body is firmly attached to the ischiopubic rami urogenital and anal triangles, however, the superficial by the superficial transverse perineal muscles. Along perineal space can be explored. The bulbospongiosus its upper lateral borders, the perineal body is attached muscles, located lateral and deep to the introitus and to the pubococcygeus, pubovaginalis, and puborectalis majora, respectively, insert into the inferior limit portions of the levator ani muscle group. of the perineal body with the superficial transverse Posterior and superiorly, the perineal body commu- perineal muscles and the subcutaneous portion of the nicates with the longitudinal fibrous sheath of the external anal sphincter. The deep part of the perineal , which starts to curve anteriorly body occupies the upper half of the space anterior to toward the posterior wall of the vagina at the level of the . the anorectal junction (Oh and Kark, 1973). Oh and Kark (1972) suggested that the external The pudendal supplies most of the innerva- anal sphincter forms a single muscle bundle in the tion to the perineal body. It is formed from the ventral female, unlike the male that appears to form distinct rami of S2–4 spinal inferomedial to the sciatic portions. Shafik (1975, 1976a,b) described the anat- nerve, descends between the coccygeus and piriformis

Fig. 2. Female perineal body (shaded area). Note the cut-aways of the pubococcygeus, bulbospon- giosus, and superficial transverse perinei muscles. Illustration by Mr. Tom Pierce. Female Perineal Body 323 muscles, and leaves the through the greater nal nodes, and internal iliac lymph nodes, in sciatic foramen. It then crosses the posterior surface of order of importance (Netter, 1989). the ischial spine and enters the perineumthrough the lesser sciatic foramen to travel along the lateral wall of MODERN ANATOMY the ischioanal fossa within the pudendal (Alcock’s) canal (Benson, 1989). The inferior rectal nerve usually The classic description of the branches off as the wraps around the includes the deep transverse perineal muscles, encap- ischial spine and subsequently supplies the external sulated within layers of the superior and inferior fas- anal sphincter, which is involved in maintaining fecal ciae of the urogenital diaphragm(Netter, 1989). Oel- continence, and provides sensory innervation to the rich (1983) contended that he could not identify the anal canal below the . At the level of the “urogenital diaphragmof Henle” as a distinct anatom- joined superior fascia of the pelvic diaphragmand the ical entity. He conducted an extensive review of the endopelvic fascia, the pudendal nerve divides again literature, performed gross and histological sections on into the dorsal nerve of the and the perineal 43 fetal pelves and 43 adult pelves at various stages of nerve. The supplies the perineal body development (66 mm crown-rump length fetuses to and the labia. Other branches of the perineal nerve 30-year-old adults) and concluded that teachings supply the external urethral sphincter muscle, which about the existence of the urogenital diaphragmwere is involved in maintaining urinary continence. The unfounded, notwithstanding their promulgation anal canal above the pectinate line is innervated by throughout the anatomical and medical literature for the uterovaginal portion of the inferior hypogastric most of the 20th century. All of the following contrib- plexus and the pelvic splanchnic nerves. Because of ute to the confusion: difficulty of dissection in the its proximity to the anal canal and its close association area, few and small skeletal muscle fibers, the replace- with the internal anal sphincter, small autonomic ment of skeletal muscle fibers by collagen bundles nerve branches to the perineal body are possible with age, the large amount of surrounding smooth (Moore, 1992). Perineal branches of the posterior fem- muscle, and an extensive connective tissue investment. oral cutaneous nerve may also provide innervation. Oelrich’s (1983) major contribution was to describe Arterial supply to the perineal body comes primar- the external urethral sphincter as encircling the mid- ily fromthe internal pudendal , one of the dle third of the length of the (Fig. 3). More branches of the anterior trunk of the internal iliac caudally the compressor urethrae and the urethrovag- artery. The accompanies the inal sphincter pass anterior to the urethra. The com- pudendal nerve through the pudendal canal and di- pressor urethrae originates fromthe ischiopubic ramus vides into the inferior rectal and perineal and and compresses the urethra, as well as pulls it inferi- the dorsal artery of the clitoris (Platzer and Monsen, orly, thus assisting in elongating the urethra. The 1989). The bulk of the perineumis supplied by the urethrovaginal sphincter complements the compressor transverse branch of the and the infe- urethrae as they pass together ventral to the urethra, rior rectal artery. Another branch of the internal iliac and they may be reciprocal in size. In early develop- artery, the , supplies the middle ment, the urethrovaginal sphincter is distinct as it third of the and may also send minor branches passes dorsally along the lateral wall of the urethra and to the superior portion of the perineal body (Wilson, vagina immediately deep to the cephalic edge of the 1988). The perineal body may also receive minor vestibular bulb. It is separated fromthe vestibular branches fromthe superior rectal artery, a branch of bulb by a thin layer of perineal membrane and inter- the inferior mesenteric artery (Netter, 1989). digitates with the corresponding muscle of the opposite Venous drainage of the perineal body is primarily side and the perineal body. With age, there is an in- accomplished via the internal pudendal and the creased density of connective tissue in the perineal body venae comitantes of the branches of the internal pu- and it becomes difficult to identify the skeletal muscle dendal artery (Moore, 1992). Drainage is assisted by fibers of the urethrovaginal sphincter behind the vagina. the vaginal venous plexus, as well as veins that com- Because of Oelrich’s studies (1983), the transversus municate with the uterine, vesical, and rectal venous vaginae muscles have replaced the deep transverse plexuses and with the bulb of the vestibule. Posteri- perineal muscle. The transverse vaginae parallel the orly, the perineal body is drained by the internal rectal compressor urethrae and radiate from it and the is- venous plexus and (Platzer and chiopubic rami to attach to the anterior portion of the Monsen, 1989). Superiorly, the middle rectal and su- lateral vaginal wall. These fibers forma very thin, perior rectal veins also provide venous drainage. Most fan-shaped muscle that attaches to the perineal mem- lymph vessels pass to the superficial and deep ingui- brane and to the anterior midpoint of the anorectal 324 Woodman and Graney

Fig. 3. Components of the former urogenital diaphragm. B, bladder; CU, compressor urethrae; IR, ischial ramus; SM, smooth muscle; TV, transverse vaginae; V, vaginal cavity; U, urethra; US, ure- thral sphincter; UVS, urethrovagi- nal sphincter; VW, vaginal wall. From Anatomical Record by T.M. Oelrich, © 1983, Wiley-Liss. Re- printed with permission of Wiley- Liss, Inc., a subsidiary of John Wiley & Sons, Inc. junction. The superior and inferior fasciae of the “uro- and descriptions of the perineal body, few authors genital diaphragm” are produced by a combination of have chosen to examine the perineal body directly; the superior fascia of the pelvic diaphragmand the however, there is a wealth of information from phys- endopelvic fascia as it passes around the margins of iologic studies. What follows is a discussion of the the urogenital hiatus. clinically important functions of the perineal body, Oelrich’s findings (1983) started to be reported in which are multiple and diverse (Table 1). the scientific literature, in part due to his participation on the 1989 International Anatomical Nomenclature Anchors the Anorectum Committee. The term deep transverse perineal mus- Wilson (1967) examined the pelves of four em- cle, however, still appears in Nomina Anatomica, 6th bryos, 27 fetuses, six full-terminfants, and 129 adults, ed. (International Anatomical Nomenclature Commit- both histologically and grossly, and described how the tee, 1989) and Terminologia Anatomica (Federative “sphincter vaginae” (pubovaginalis) muscle passes Committee on Anatomic Terminology, 1998). At the through the perineal body and blends with the deep writing of this article, 29 scientific journal articles have part of the external anal sphincter, anchoring the per- quoted his original work over the past 16 years. Oel- ineal body to the anal canal. In addition, the upper rich has several proponents in the gynecological and surface of the perineal body joins with the rectovagi- urological fields and his findings have been confirmed nal septum(Denonvilliers’ fascia) and into its very utilizing other technologies (Myers et al., 1998), and posterior and superior aspects pass fibers fromthe have been incorporated into anatomical texts (Wood- longitudinal muscle layer of the muscularis externa of burne and Burkel, 1988; Platzer and Monsen, 1989; the anterior wall of the rectum. The perineal body is Moore, 1992; Slaby et al., 1994; Williams et al., 1995). also attached to the muscles in the superficial and In other texts, his findings have been overlooked deep perineal spaces. Thus, through the perineal (Wilson, 1988; Netter, 1989; Frick et al., 1990; Spence, body, the various components of the external anal 1990; Snell, 1992; Hall-Craggs, 1995; Rohen et al., 1998). Some gynecology texts have incorporated his TABLE 1. Clinical Importance of the Perineal Body concepts, but Oelrich’s findings (1983) may as yet be considered minutiae. Anchors the Anorectum Anchors the Vagina Prevents Expansion of the Urogenital Hiatus Provides a Physical Barrier Between the Vagina and Rectum CLINICAL IMPORTANCE OF THE Episiotomy PERINEAL BODY Maintains the Orgasmic Platform Maintains Urinary Continence Because of the difficulties that Oelrich (1983) and Pudendal Nerve Injury Oh and Kark (1973) experienced in their dissections Maintains Fecal Continence Female Perineal Body 325 sphincter, superficial transverse perineal muscles, le- selection of the A-P diameter measurement in the vator ani (pubococcygeus, pubovaginalis and puborec- American Urogynecologic Society/International Con- talis) and the median part of the posterior border of tinence Society sanctioned Pelvic Organ Prolapse the perineal membrane anchor the anterior anorectal Quantification Exam(Bumpet al., 1996). Kelly (1928) region to the pelvic ring. observed that it was actually the levator ani and not the perineal body that closes the urogenital hiatus. Anchors the Vagina DeLancey and Hurd’s (1998) data were consistent DeLancey (1992) described the support of the va- with this finding. The urogenital hiatus is sealed by gina at three distinct levels. The immobile inferior the vaginal walls, endopelvic fascia, and urethra. As one-third of the vagina, Level III, fuses with the the urogenital hiatus increases in size, however, an perineal membrane, levator ani muscles, and perineal open space develops in the pelvic floor and gravity body. DeLancey reported that an important function tends to fill this space with a , , or of Level III supporting structures includes keeping the uterine . Once the urogenital hiatus has the vagina closed. Defects in Level III support com- opened up, the vaginal wall and cervix lie unsup- monly predispose to total uterine procidentia or vagi- ported, and the endopelvic fascia is called upon to nal eversion. An intact perineal body can delay or hold the pelvic organs in place. In predisposed indi- prevent these conditions by maintaining the prolaps- viduals the constant load fromabdominalpressure on ing tissues above the levator plate (the central tendon this fascia can cause its failure with the development of the levator ani muscles) and the urogenital hiatus. of significant prolapse. Ultimately, it is the perineal In 1999, DeLancey histologically and macroscopi- body that acts as the final mechanism for preventing cally examined 42 fresh and 22 fixed female pelves in prolapse beyond the urogenital hiatus. As the perineal serial section. He described how the perineal body membrane and tendinous arches of the pelvic fasciae served as the central connection between the two tighten, the entire perineal body redirects abdominal halves of the perineal membrane. As force is directed pressure and dissipates gravity to prevent expansion upon the vagina fromabove, the fibers of the perineal of the urogenital hiatus. membrane, which are laterally and posteriorly at- tached to the ischiopubic rami and perineal body, Provides a Physical Barrier Between the Vagina respectively, become taut and resist downward dis- and Rectum placement. At Level II (middle one-third of the va- Hakelius (1979) proposed that the perineal body gina), the lateral attachments of the vaginal canal, was integral in maintaining the structural integrity of including the levator ani muscles and the tendinous the fecal continence mechanism by acting as a phys- arches of the pelvic fascia (arcus tendineus fasciae ical barrier or “spacer” between the rectumand va- pelvis) also become taut. This anatomical arrange- gina, thus protecting the rectumduring childbirth. ment underlies the structural interdependence be- The shortening of the puborectalis sling pulls the tween the support offered by the perineal body at anorectal junction anteriorly and superiorly, making Level III through its attachment to the perineal mem- the anorectal angle more acute, and thereby maintain- brane and the suspension of the vagina by the perineal ing fecal continence. Damage to the perineal body or body at Level II through its multiple connections with the attached puborectal sling may lead to anal incon- the tendinous arches of the pelvic fasciae (and the tinence. Hakelius (1979) used perineorrhaphy (repair levator ani musculature). of the perineal body) as the primary procedure for anal incontinence in 15 patients and achieved an 80% res- Prevents Expansion of the Urogenital Hiatus olution of incontinence. DeLancey and Hurd (1998) examined the relation- Henry et al. (1982) measured the distance between ship between pelvic organ prolapse and the size of the the perineal body and an imaginary line drawn be- urogenital hiatus. They found that the average size of tween the ischial tuberosities and reported an average the urogenital hiatus in the levator ani muscles was 5 distance of 2.5 cm. They also describe a “descending cm2 (calculated using the anteroposterior measure- perineumsyndrome,”where the perineal body lies at ment from the external urethral meatus to the frenu- a lower level than normal and descends an average of lumof the [fourchette] and the greatest 2 cmwith the Valsalva maneuver.In this condition, transverse diameter). An increase in the size of the the acute anorectal angle, so important in fecal conti- urogenital hiatus was directly related to progressively nence, is disrupted; it may be caused by a loss of larger pelvic organ prolapses that were correlated perineal body volume, detachment of the rectovaginal more to the anterior-posterior (A-P) diameter than to septum, or a widening of the urogenital hiatus after the transverse diameter. This fact was key in the childbirth. 326 Woodman and Graney

TABLE 2. Layers Traversed During Uncomplicated Second-degree Episiotomy* Midline type Mediolateral type EpitheliumEpithelium Superficial transverse perinei Bulbospongiosus Greater vestibular (Bartholin’s) gland (possible) Perineal membrane Bulbospongiosis Urethrovaginal sphincter and transversus vaginae Superficial transverse perinei Rectovaginal septum (possible) Perineal membrane Urethrovaginal sphincter and transversus vaginae *Adapted fromSultan et al. (1995).

Zetterstroemet al. (1998) used endoanal ultrasound maternal blood loss, increased perineal body injury measurements of the perineal body to assess anterior and anal sphincter damage, improper wound healing, anal sphincter defects. A perineal body thickness of and postpartumpain. less than 10 mm was found in 93% of patients with Episiotomy techniques differ according to geo- sphincteric defects. This ultrasonographic measure- graphic location. Midline episiotomy (where a linear ment may be an important reflection of the relation- surgical incision is made in the midline of the vagina ship between the status of the perineal body and the and perineumto increase vaginal capacity) is predom- anal sphincter musculature. inant in the United States and at some centers in Canada. Beynon (1974) advocated the use of midline Episiotomy episiotomy over mediolateral episiotomy (where the In addition to spontaneous damage to the perineal incision is toward the ipsilateral ), the body, damage also occurs iatrogenically through the general preference of obstetrical providers in Great performance of an episiotomy. Episiotomy is one of Britain. Midline episiotomy was deemed to be easier the most common procedures performed in obstetrics; to repair and to heal better than mediolateral episiot- unfortunately, it is often the least-experienced intern omy. or resident who is relegated to repair an episiotomy. Median episiotomy, however, has been associated Experience and knowledge of the applicable anatomy with severe perineal lacerations in primiparous contribute significantly to good repair. Sultan et al. women. Labrecque et al. (1997) reported an overall (1995) surveyed the training in episiotomy and its 15.4% incidence of anal sphincter disruption; 20.6% repair and found it to be wholly insufficient. Less than occurred in women with midline episiotomy and 4.5% 20% of physicians felt their training in perineal anat- in women who did not have an episiotomy. This omy to be of high standard, and more than 50% of difference persisted even after adjustment for deliv- physicians and midwives misidentified the muscles ery type, weight, experience of physician, baby’s cut during an uncomplicated episiotomy (Table 2). A great deal has been written about in head circumference, , and epidural the last 130 years. Thacker and Banta (1983) per- anesthesia. The relationship between midline episiot- formed an extensive review of the English-language omy and anal sphincter disruption has been exten- scientific literature (1860–1980) on the risks and ben- sively documented by other investigators as well efits of episiotomy. Notwithstanding a lack of clear (Klein et al., 1994; Handa et al., 1996; Klein et al., evidence of its efficacy, episiotomy was performed in 1997; Sultan, 1997; Wood et al., 1998; Albers et al., 60% of all deliveries in the US and in 50–90% of 1999; Zetterstroemet al., 1999). primigravid patients. Subsequently, Wooley (1995a,b) Although mediolateral episiotomies are technically published two review articles that dealt with episiot- more difficult to repair, their use appears to be pro- omy from 1980–94. He reported that episiotomy was tective, at least in nulliparous women (Poen et al., shown to reduce anterior vaginal lacerations, but, 1997). Wood et al. (1998) reported a 1.2% incidence of more significantly, episiotomy did not provide the third degree anal sphincter tears in a retrospective maternal and fetal benefits normally reported by its study of 9,631 women who received a mediolateral proponents. These benefits included prevention of episiotomy. Studies of occult sphincter damage with perineal damage and its sequelae, prevention of pelvic endoanal ultrasonography, however, have shown that floor relaxation and its sequelae, and protection of the neither midline nor mediolateral episiotomy prevents newborn fromintracranial hemorrhageor intrapartum anal sphincter disruption (Sultan, 1997). See Table 3 asphyxia. In fact, episiotomy has been shown to sub- for a comparison between midline and mediolateral ject the patient to increased risk caused by greater episiotomy. Female Perineal Body 327

TABLE 3. Comparison of Midline Versus Mediolateral Maintains the Orgasmic Platform Episiotomy* Masters and Johnson’s (1966) book, Human Sexual Episiotomy type Response, suggested that the perineal body was an Characteristic Midline Mediolateral integral part of the “orgasmic platform,” an area of Surgical repair Easy More difficult localized vasocongestion during the plateau level of Faulty healing Rare More common the sexual response. This platform, which encom- Postoperative pain Rare Common Anatomical results Excellent Occasionally faulty passes the entire inferior one-third of the vagina, to- Blood loss Less More gether with the labia minora, reflects the vagina’s Dyspareunia Rare Occasional anatomico-physiologic expression of . When Extensions Common Uncommon the perineal body is damaged, this platform is dam- *Adapted fromRaminand Gilstrap (1994). aged. Klein et al. (1994) investigated primiparous and multiparous women and found that sexual functioning Because of the concern about the relationship be- was best in women with spontaneous or no tears and tween episiotomy and severe perineal damage, physi- that during the first three months of the postpartum cians have begun to speak out against the routine or period, perineal pain was least for women who gave liberal use of episiotomy (Helewa, 1997; Meyers-Helf- birth over an intact perineum. Perineal suturing itself gott and Helfgott, 1999). When a conscious change in may be associated with an increased incidence of the liberal use of episiotomy was attempted, the inci- perineal pain (Gordon et al., 1998). Benyon (1974) dence of tears in the external anal sphincter remained advocates midline episiotomy over the mediolateral unchanged; however, women had an increased inci- technique because it is associated with less pain and dence of delivering with an intact perineum(Henrik- dyspareunia. Sleep and Grant (1987), however, re- sen et al., 1994). ported on a three-year follow-up study that compared McCandlish et al. (1998) described a hands-on liberal use of episiotomy to a restrictive policy and method of supporting the perineum and assisting the found no benefit in the prevention of long-termdys- delivery of the shoulders, resulting in a lower episiot- pareunia. omy rate. Besides an unsupported perineum, other If perineal damage and its attendant pain are sig- factors favoring severe perineal damage include: for- nificant, so can be the corresponding sexual conse- ceps delivery, increased fetal size (Ͼ4,000 g), pro- quences. Haademet al. (1988) surveyed womenwho longed second stage (pushing) of labor, primiparous received episiotomy and found that 48% had pelvic delivery, and occiput posterior position. Other factors floor symptoms, such as perineal pain and dyspareu- that protect against severe perineal damage include nia, particularly when childbirth perineal damage in- vacuum-assisted delivery and cesarean section before cluded extension into the anal sphincter. labor (Sultan et al., 1994; Handa et al., 1996). Great importance is often placed on a ’s When evaluating the use of episiotomy in the man- body image and sexual functioning. In Brazil, body agement of labor, an obvious concern is pain. Albers et image and sexual functioning are perceived as threat- al. (1999) investigated genital tract trauma in second- ened by vaginal delivery, leading to a comparatively stage labor with a restrictive episiotomy policy and high cesarean-section rate (Souza, 1994). Episiotomy found that painful trauma occurred in 85% of has even been viewed as a formof genital mutilation (59% required suturing); even with a first- or second- (Wagner, 1999). Compared to a natural tear, episiot- degree tear, pain and dyspareunia were significant. omy results in more bleeding and pain, more perma- Gordon et al. (1998) compared women who had re- nent vaginal deformity, and more temporary and long- ceived episiotomy repair by the performance of a termsexual dysfunction (Raminand Gilstrap, 1994). two-layered closure leaving the skin unsutured, vs. by the traditional three-stage closure with skin closure. Maintains Urinary Continence They found that by leaving the skin unsutured women had less pain and dyspareunia at three-month The urinary continence mechanism is complex and follow-up. Ramin and Gilstrap (1994) reported that 1 depends, in large part, upon the coordination of the in 20 women with a fourth-degree tear develop early involuntary detrusor and intrinsic urethral sphincteric infection, wound dehiscence, or both, which can also muscles. The levator ani muscle and external urethral result in pain and dyspareunia. Mackrodt et al. (1998) sphincter muscle function as back-up mechanisms, found that post-episiorrhaphy pain, analgesic use, and both of which are under voluntary control. The levator wound breakdowns can be limited with the use of plate also provides a dynamic backdrop for the normal polyglactin 910 suture, as compared to catgut. continence mechanism, resisting posterior rotational 328 Woodman and Graney descent of the vagina and overlying urethrovesical stretches the pudendal nerve by 20% of its length. junction during levator contraction. Childbirth can Disruption of Denonvilliers’ fascia during vaginal de- damage the pelvic musculature; consequently, poste- livery can separate the perineal body from this immo- rior rotational descent of the bladder neck necessary bile fascia and allow perineal descent with a simple for normal voiding can also occur at times of increased Valsalva maneuver of up to 1.1 cm (Snooks and Swash, intra-abdominal pressure. 1984; Snooks et al., 1986). Descent of as little as this Benson (1996) summarized the neurogenic hypoth- distance (and stretching of the pudendal nerve by esis of . Weakening of the pelvic 12% of its length) can cause permanent pudendal floor musculature after childbirth occurs secondary to neuropathy, and repeated events are additive. Similar direct damage and partial denervation. Ninety-five to carpal tunnel syndrome, the terminal branches of percent of women with stress urinary incontinence the pudendal nerve undergo demyelination. Ho and have prolonged perineal nerve conduction times, com- Goh (1995) suggested a linear relationship between pared to only 4% of women without stress urinary perineal descent and pudendal nerve damage, based incontinence. This suggests a double neuromuscular on an increase in pudendal nerve terminal motor la- pathology: direct compression, stretch, and devascu- tency. larization of the pudendal nerve resulting in levator Benson (1996) summarized other common neuro- ani atrophy and loss of urethral and bladder support. genic mechanisms of injury. Pressure as low as 80 mm Ryhammer et al. (1995) reported on the relation- Hg on the perineuriumcan lead to cessation of blood ship between urinary incontinence symptomatology flow to the axons, and pressure during a vaginal de- and the number of repeated vaginal deliveries. The livery can easily surpass this limit (up to 240 Ϯ 82 mm risk for urinary incontinence was additive: 3.3%, 1.0%, Hg). Cessation of blood flow for more than 8 hr may and 6.8% after one, two, and three deliveries, respec- lead to thrombosis without recovery of neural func- tively. The difference was significant after three vag- tion. Thus, vascular compression during delivery may inal deliveries, as compared to the first two. lead to neuropathic and myopathic dysfunction. Dis- In a survey of Danish women, Foldspang et al. section neuropathy may occur as a result of vaginal (1999) investigated factors associated with urinary in- pelvic reconstructive surgery. continence. Episiotomy and perineal suturing corre- Because pudendal neuropathy has been shown to lated to incontinence; however, using a multivariate be an etiologic factor in both urinary and fecal incon- analysis, only perineal suturing continued to be asso- tinence (Snooks and Swash, 1984; Snooks et al., 1986), ciated with urinary incontinence. Sleep and Grant electrophysiologic studies may allow the identification (1987) found no benefit fromepisiotomyin the pre- of the most effective pelvic reconstructive surgery. vention of urinary incontinence. It appears that both Pudendal neuropathy may affect the efficacy of tradi- spontaneous or deliberate trauma to the perineal body tional procedures and may indicate that a more tar- is associated with urinary incontinence. geted procedure should be recommended. The urethrovaginal sphincter attaches into the per- Direct branches of the ventral rami of the S3–S4 ineal body and contributes to the external urethral spinal nerves (and perhaps branches of the pudendal sphincter (Oelrich, 1983). Because neurologic and di- nerve) supply the puborectalis portion of the levator rect damage to the pelvic floor can occur during de- ani muscle (Hollabaugh et al., 1997), and these nerves livery, subsequent loss of urethrovaginal sphincter may also be involved in traction injury. Allen et al. function may be just enough to make a woman incon- (1990) used concentric needle EMG, pudendal nerve tinent. conduction, and perineometer measurements to de- termine the extent of levator ani damage during child- Pudendal Nerve Injury birth. In 80% of women, there was EMG evidence of The terminal ends of some of the perineal and denervation at 2 months postpartum and impairment inferior rectal branches of the pudendal nerve are of pelvic floor contraction. Women who delivered by tethered in the perineal body. Thus, Kiff and Swash elective cesarean section before labor commenced (1984) suggested that because the pudendal nerve is were spared electrophysiologic damage to the pelvic bound tightly by connective tissue as it wraps around floor musculature. Cesarean section was not protective the ischial spine, it is predisposed to damage distal to if the patient labored, however, suggesting that labor this site when it is stretched by the perineal descent itself is an important cause of denervation. that occurs during the second stage of labor or with Deindl et al. (1994) reported that birth trauma was excessive straining at defecation (Henry, 1982; Ben- associated with asymmetric denervation of the pelvic son, 1989). Henry et al. (1982) estimated that a peri- floor and suggested that coordination of levator ani neal descent of 2 cm, which may occur during labor, contraction is also important in urinary continence. Female Perineal Body 329

Multiparity, forceps delivery, increased duration of DeLancey et al. (1997) examined the anatomy of the second stage of labor, a third-degree , the internal and external anal sphincter in relation to and a linear relationship with increasing birth weight acute fourth-degree midline perineal body lacerations. were associated with pudendal nerve damage. These investigators reported that the internal anal sphincter lies over the submucosa of the anal canal as Maintains Fecal Continence a distal condensation of the longitudinal layer of the The most important functional role of the perineal muscularis externa of the rectum. Of clinical impor- body, because of its very intimate relationship to the tance was the observation that the internal anal anal canal and anal sphincter muscles, is its contribu- sphincter in these patients retracted laterally into the tion to fecal continence. Shafik (1975, 1976a,b) de- surrounding tissue because of its constant muscular scribed the external and internal anal sphincters as activity. If a physician is not vigilant in repairing a inserting into, passing through, and being invested by severe perineal body laceration, the internal anal the perineal body. It follows that when damage to the sphincter can retract, not be repaired, and result in the perineal body occurs, direct (or indirect) extension loss of internal anal sphincter function with subse- into the anal sphincters and a loss of fecal continence quent anal urgency or liquid stool incontinence. is possible. As women age, the strength of both the external is a disturbing and life-altering and internal anal sphincter musculature decreases, ev- disorder. Sphincteric control is fundamental in human idenced by a decrease in resting and squeeze mano- socialization and its impairment may result in severe metric pressure (Poos et al., 1986). As anal sphincter emotional and social disruption. Schoetz (1985) said muscle strength deteriorates, a patient may no longer “loss of voluntary control of bowel movements results be able to compensate for long-term anal sphincter in progressive isolation of the affected individual and disruption. Nygaard et al. (1997) questioned women alienation from family members, with devastating psy- with anal sphincter disruption 30 years after delivery. chosocial impact.” Because of the sensitive nature of Those women with anal sphincter disruption had sig- the problem, embarrassment, and perceived social nificantly more bowel sequelae than women with a stigmata of the condition, fewer than 50% of women simple episiotomy or cesarean section; however, as the will report it to their doctors. Estimates of fecal incon- women aged, the three groups became very similar tinence incidence range from0.4–17% of adult ambu- suggesting that age acts as an equalizer, rather than latory women, and may be as high as 50% in institu- exacerbating previously existing symptoms. tionalized patients (Kamm, 1994; Jackson and Hull, A normal perineum on clinical examination does 1998). Approximately 13% of women have fecal ur- not preclude underlying sphincter damage. Nielsen et gency and 30% have structural changes on ultrasound al. (1992) reported that digital anal examination de- (Kamm, 1994). Sultan et al. (1993) reported that 13% tects only 85% of cases of persistent anal sphincter of primiparous and 23% of multiparous women have damage. Frudinger et al. (1997) reported a 43% occult fecal urgency or incontinence at 6 weeks postpartum. sphincter disruption rate with a normal digital exam Zetterstroemet al. (1999) described the vagina as and no visible perineal evidence of trauma. The ad- slightly ‘J-shaped’ with the bottomof the ‘J’ being vent of endoanal ultrasonography has allowed physi- closely associated with by the rectum, anal canal, and cians to determine unrecognized anal sphincter the perineum. Therefore, most of the uterine pressure muscle damage postpartum. Burnett et al. (1991) during the second stage of labor is directed toward the demonstrated ultrasonographic sphincter defects in perineal body and anorectum. Anal rupture during patients suffering fromanal incontinence: 90% had labor carries a high risk (20–50%) of anal incontinence external anal sphincter defects, 65% had internal anal (Haademet al., 1988; Bek and Laurberg, 1992; Sultan, sphincter defects, and 44% had disruption of the per- 1997). The internal anal sphincter is responsible for ineal body suggested by significant attenuation during up to 80% of anal resting pressure and for liquid stool imaging. continence. The external anal sphincter is primarily In a groundbreaking study, Sultan et al. (1993) responsible for flatal continence and produces about reported that 35% of primiparous women and 44% of 80% of the maximum squeeze pressure on manomet- multiparous women had occult sphincter disruption ric testing (Mitrani et al., 1998). Sultan et al. (1994) on ultrasound 6 weeks after delivery and concluded demonstrated that those patients with anal inconti- that most damage occurred during the first vaginal nence or fecal urgency had both internal and external delivery. They identified no sphincteric disruption in anal sphincter defects on ultrasound, and significantly women undergoing cesarean section or vacuum deliv- lower manometric anal pressures. eries. 330 Woodman and Graney

Several authors have suggested that anal sphincter (Nielsen et al., 1992). Eighty-five percent of anally disruption is the most important contributing factor to incontinent women have persistent structural defects fecal incontinence (Bek and Laurberg, 1992; Kamm, after a third-degree repair and 50% of women remain 1994; Sultan, 1997) and that the most common pre- symptomatic despite repair immediately after delivery disposing factor for sphincter disruption is the use of (Kamm, 1994). Transient postpartum anal inconti- forceps (Haademet al., 1988; Sultan et al., 1993; nence is a reliable predictor of future anal inconti- Kamm, 1994; Poen et al., 1997; Wood et al., 1998). nence (Bek and Laurberg, 1992). Johanson et al. (1993) compared forceps to vacuum We have already discussed pudendal neuropathy in extraction and found an incidence of 17 and 11%, relation to urinary incontinence; the neurogenic basis respectively, of anal sphincter damage. of fecal incontinence is even better established Other risk factors for anal sphincter rupture include (Snooks et al., 1984, 1985; Sultan et al., 1994; Ryham- primiparity (Haadem et al., 1988; Poen et al., 1997; mer et al., 1995; Kafka et al., 1997; Jackson, 1998). Wood et al., 1998), abnormal presentations other than Pudendal nerve injury and traumatic anal sphincter occiput anterior (Haademet al., 1988), large babies disruption subsequent to vaginal delivery are the two Ͼ3,800–4,000 g birth weight (Haademet al., 1988; primary causes of fecal incontinence (Jackson, 1998). Poen et al., 1997; Wood et al., 1998), oxytocin admin- Snooks et al. (1985) investigated patients with anterior istration (Haademet al., 1988; Poen et al., 1997), external anal sphincter damage and fecal incontinence episiotomy (Wood et al., 1998), second stage of labor through physical examination, anal ultrasonography, Ͼ1 hr (Poen et al., 1997; Wood et al., 1998), and and pudendal nerve terminal motor latency studies. epidural anesthesia (Poen et al., 1997). They found a 60% incidence of pudendal neuropathy, The traditional end-to-end anal sphincter repair has suggesting that muscle and nerve damage often coex- been associated with up to a 50% failure rate and, ist, producing a double pathology. therefore, has come into question. Stricker et al. Some authors suggest that pudendal neuropathy is (1988) compared four different anal sphincteroplasty the predominant factor differentiating patients with procedures and found that deep external anal sphinc- minor leakage versus gross anal incontinence. For ter plication with perineal body reconstruction and instance, Kafka et al. (1997) prospectively measured anoplastic skin closure was superior. This procedure pudendal nerve terminal motor latencies (PNTML) involves dissecting up the rectovaginal septumand in women presenting with abnormalities of defeca- serial plication of the medial part of the levator ani and tion. Less than 35% of patients with leakage alone had the superficial and deep external anal sphincters. Un- abnormal PNTMLs, whereas 77.4% of PNTMLs fortunately, success rates were not cited. were abnormal for women with gross incontinence. Sultan (1997) suggested that the techniques found Each group showed significant decreases in the fol- most effective in secondary episiorrhaphy may also be lowing manometric parameters: resting and squeeze effective in primary closure under the appropriate manometric pressures, volume pressures, and func- conditions. There are several ongoing investigations tional sphincter length. of overlapping sphincteroplasty (in which the internal Snooks et al. (1984) suggested that the pudendal anal sphincter is plicated in the midline and the ex- nerve damage caused by vaginal delivery might be ternal anal sphincters are divided in the midline, over- cumulative in multiparous women. Ryhammer et al. lapped, and sutured) for the repair of sphincter rup- (1995) distributed a questionnaire examining anal in- ture at the time of delivery. For example, Londono- continence symptomatology with repeated vaginal de- Schimmer et al. (1994) reported a 75% fair to excellent liveries without obstetrical tears of the anal sphincter. result after 5 years in women who underwent overlap- They found a risk of permanent flatal incontinence of ping sphincteroplasty for fecal incontinence. The out- 1.2, 1.5, and 8.3% after one, two, and three vaginal comes were not related to the cause of injury, but an deliveries, respectively. anterior overlap was significantly better than a poste- rior one. Pudendal neuropathy, infection, and impac- RECOMMENDATIONS tion were often associated with procedure failure. Sul- tan (1997) reported that poor outcomes after primary Protection of the perineal body is integral to vaginal repair are often related to persistent sphincteric dis- delivery and its ancillary procedures, which are them- ruption rather than to pudendal neuropathy. selves common causes of perineal body damage. Ship- The persistence of sphincteric disruption occurs in man et al. (1997) suggested that perineal massage 50–58% of women (Nielsen et al., 1992; Sultan et al., during the second-stage of labor may reduce the epi- 1994). Although some patients with persistent disrup- siotomy rate, the incidence of instrumental deliveries, tion improve, 29% continue to have bowel sequelae and anal sphincter damage. Controlling the speed of Female Perineal Body 331 vaginal delivery with a hands-on approach is impor- laceration, but is found on ultrasonography to have an tant to minimize shearing neuropathy and uncon- asymptomatic occult third-degree defect, it would be trolled delivery of the shoulders, which may extend a difficult to justify not repairing the whole defect. perineal laceration or episiotomy. Episiotomy has not The best type of perineal repair is yet to be deter- proven effective in preventing maternal or fetal mor- mined. However, physicians repairing first- and sec- bidity and, consequently, should be restricted to cer- ond-degree lacerations or incomplete anal disruptions tain indications, such as cases of fetal distress, mal- might be well-advised to perform a layered anatomical presentation, persistent occiput-posterior position, technique in the fashion described by Stricker et al. and shoulder dystocia (Sultan and Kamm, 1997). Pro- (1988) and Wheeless (1998). Patients with complete phylactic episiotomy in women who have had previ- anal sphincter disruption may benefit from a primary ous anal sphincter disruption does not seemto be overlapping anal sphincteroplasty procedure. None- effective in preventing recurrence of such damage theless, perineorrhaphy and reattachment of the per- (Sultan, 1997). Henriksen et al. (1994) recommend ineal body to Denonvilliers’ fascia and the anal keeping episiotomy rates below 30% and, if instru- sphincters must be the goal. mental assistance is necessary, vacuum extraction has Sultan et al. (1995) demonstrated that the “training proven safer than forceps (Poen et al., 1997). Vacuum of midwives and trainee doctors in perineal anatomy extraction is currently the procedure of choice recom- and repair has been shown to be poor” and demanded mended by the Royal College of Obstetricians and that education in this area be enhanced. Unfortu- Gynaecologists for instrumental deliveries (Sultan and nately, because delivery rates have consistently fallen Kamm, 1997). over the last 30 years in the United States, trainee The work of Allen et al. (1990) suggests that exposure to episiotomy and repair is limited. It is not women who are delivered by elective cesarean section uncommon for a trainee or a physician with a limited before the onset of labor are spared electrophysiologic obstetrical practice to repair only one or two fourth- damage to the pelvic floor musculature. Despite the degree lacerations per year. Without adequate instruc- benefits of the modern surgical methods, however, tion, practice models, and supervision by trained sur- cesarean section is not without risk. Few physicians geons, the number of women with urinary or fecal have been bold enough to recommend elective cesar- incontinence and pelvic organ prolapse may grow. ean section to their patients; nonetheless, Sultan and Wheeless (1998) proposed the development of an Stanton (1996) warn that the request rate for elective early-morning episiorrhaphy service. All patients with cesarean section may rise as more women worry about severe perineal trauma from the previous evening’s their quality of life after the trauma of a vaginal de- deliveries would be kept at bed rest, hydrated, and livery. Souza (1994) reported on the status of Brazil’s given antibiotics and pain medication until the morn- “Cesarean Section On Demand” policy. He warned ing. A senior gynecologic surgeon would then attend that patients’ rights could become confused with the the repair of all third- and fourth-degree tears in a transference of physicians’ attitudes through patient controlled setting, with adequate instrumentation, counseling. Selected women may benefit fromcesar- lighting, and assistance. This would provide an opti- ean delivery, but it should be restricted to women who mal environment for formal episiorrhaphy teaching have undergone repair for incontinence or pelvic or- and improvement of outcomes. gan prolapse. Secondary repair of sphincter defects may be less If damage occurs during vaginal delivery, steps can straightforward, especially if patients present with in- be taken to minimize morbidity and reestablish anat- continence. Electrophysiologic studies that indicate omy. When used for primary repair, Mackrodt et al. neuropathy can be used to enhance the selection of (1998) found polyglactin sutures superior to catgut in the ideal pelvic reconstructive surgical candidate: if a decreasing postoperative pain, analgesic use, and neurologic deficit is present, the physician could with- wound breakdowns. Gordon et al. (1998) demon- hold traditional reconstructive procedures in lieu of strated that women had less pain and dyspareunia at more complicated procedures (Benson, 1996). More three months postpartum when a layered perineal targeted procedures may be indicated if intrinsic ure- repair was performed in women who had first- and thral sphincteric deficiency or an end-stage external second-degree perineal lacerations, leaving the skin anal sphincter are encountered. unsutured. For women with complicated deliveries, such as forceps usage (a predictor of occult sphincter SUMMARY damage; Sultan, 1997), endoanal ultrasonographic eval- uation may be useful in identifying occult sphincteric The perineal body is a complex structural entity injuries. If a patient appears to suffer a second-degree between the terminal ends of the urogenital and gas- 332 Woodman and Graney trointestinal systems. The interlocking muscular, fas- damage following childbirth revealed by anal endosonogra- cial, and fibrous components make dissection and de- phy. Br J Radiol 64:225–227. scription of the anatomy difficult. Despite the paucity Deindl FM, Vodusek DB, Hesse U, Schuessler B. 1994. Pelvic of literature on the perineal body, it is an extremely floor activity patterns: comparison of nulliparous continent and parous urinary stress incontinent women. A kinesiolog- important structure. It is commonly injured during ical EMG study. Br J Urol 73:413–417. labor, and an unrepaired or improperly repaired lacer- DeLancey JOL. 1989. Anatomy and of the lower ation can compromise the functional capacity of the urinary tract. Obstet Gynecol Clin 16:717–731. urogenital and gastrointestinal systems, as well as as- DeLancey JOL. 1992. Anatomic aspects of vaginal eversion sociated peripheral nerves and the muscles they in- after hysterectomy. Am J Obstet Gynecol 166:1717–1728. nervate. Components of the urinary and fecal conti- DeLancey JOL, Toglia MR, Perucchini D. 1997. Internal and nence mechanism insert into the perineal body, which external anal sphincter anatomy as it relates to midline serves as the central anchor for the vagina and ano- obstetric lacerations. Obstet Gynecol 90:924–927. rectum, and a terminal insertion site for part of the DeLancey JOL, Hurd WW. 1998. Size of the urogenital hiatus in the levator ani muscles in normal women and women external urethral sphincter (urethrovaginal sphincter). with pelvic organ prolapse. Obstet Gynecol 91:364–368. The perineal body is stimulated during intercourse DeLancey JOL. 1999. Structural anatomy of the posterior pel- and inasmuch as it attaches to the various levator ani vic compartment as it relates to rectocele. Am J Obstet muscles, narrows the urogenital hiatus. Gynecol 180:815–823. Unfortunately, repair of a perineal laceration or Federative Committee on . 1998. Ter- episiotomy is often relegated to an inexperienced res- minologia anatomica. Stuttgart: Thieme. ident or physician. 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