Imperforate Anal Membrane

Table 8.9 Wingspread Conference classification

Level of anomaly



A. Rectovesical fistula

B. Without fistula

2. Rectal Atresia

1. Anorectal agenesis

A. Rectovaginal fistula

B. Without fistula

2. Rectal Atresia


1. Rectourethral fistula

2. Anal agenesis without fistula

1. Rectovestibular Fistula,

2. Rectovaginal fistula

3. Anal agenesis without fistula


1. Anocutaneous (perineal) fistula

2. Anal stenosis

1. Anovestibular (perineal) fistula,

2. Anocutaneous (perineal) fistula

3. Anal stenosis


Rare malformations

Persistent cloacal anomaly Rare malformations

complex, it allowed ARM to be viewed in a structured fashion. "Intermediate" was later added to this classification to describe those lesions where the rectum ends below the PC line.

In 1964 Santulli proposed his classification system, which was based on the work of Ladd and Gross. This also divided lesions into low, infralevator, and high, supralevator (Table 8.7) [66].

In 1970 the "International" classification was proposed at a symposium on Anorectal Malformations at the paediatric surgical congress in Melbourne in order to further decrease confusion (Table 8.8). Based on the early work of Smith and Stephens, the 1970 International classification was based on the principles of normal and abnormal anatomy and divided the lesions into three groups high (supralevator), intermediate and low (transl-evator). Although it proved much too complex for most surgical groups due to the fact it contained nearly 40 subtypes, it is still in use in the literature and is the primary reporting mechanism for the JSGA (Fig. 8.1) [55].

There are several terms that are used quite commonly in the classifications that can cause confusion for the modern reader. The term "covered anus" has been used to describe both the presence of the anal membrane and the cutaneous fistula. It was defined by Smith et al. in 1970 as a normally placed anus that is covered by excessive development of the genital folds or a fused congenital median band [58]. "Covered anus incomplete" is described as the commonest male anomaly, which is best described as a low perineal cutaneous fistula [58]. The "perineal groove" describes a normal vestibule but with a groove extending from the vestibule to the anus, which is both normal sized and positioned. The "perineal canal" is defined as a normal anus and vestibule with the presence of a fistula from the anal canal to the fossa na-vicularis [58].

The "International" classification also describes the anovulvar fistula as a variation of the covered anus with a fistula into the posterior fourchette. The vulvar anus was viewed as a variation of the anterior anus with so little development of the perineum that the anus, which is normal, is in the vestibule. The term rectocloacal fistula is used to describe all situations where the rectum, bladder and urethra enter a single channel as a common cloaca. The 1970 classification proposed that "rectovesical fistula" be used to describe the rectum entering the bladder between two separate vaginas to form a "common cloaca" at the bladder outlet [58].

The term "ectopic" anus still excites debate. It is used to describe a stenosed anus that has migrated to the vulva or, more commonly, the vestibule in the female, or any abnormally positioned anal opening in the male. It is also described as an anterior displacement of the anus and "anterior ectopic anus". It was on occasion also used to describe rectovaginal fistu-lae [67]. An ectopic anus is described as an anal index of less than 0.34 in girls and less than 0.46 in boys. The anal index is defined as the ratio of the scro-tal-anal distance to the scrotal-coccygeal distance in males, and as the ratio of the fourchette-anal distance to the fourchette-coccygeal distance in females [68]. Kluth's embryological and histological evidence of hindgut development implies that any abnormal anal opening could be viewed as an anal fistula. Peña argues strongly from his experience of 1,460 patients that a normal anus surrounded by a normal voluntary

Anorectal Malformations
Fig. 8.2 Perineal fistula or an anterior "ectopic" anus

sphincter in an abnormal position does not occur and that the term is overused (Figs. 8.2 and 8.3) [69].

New research and variations in surgical technique in the late 1970s and early 1980s altered previously fixed concepts. This led to the "Wingspread classification", which evolved from a conference held in the Wingspread Convention Center, Racine, Winconsin (USA) in 1984 [70]. It was created in order to update the "International" Melbourne classification that was described at the time as "unwieldy". It is based on high, intermediate and low anomalies and is presented in Table 8.9. Rarer subtypes that had cluttered the 1970 classification were removed. The cloacal lesion was also placed in its own separate class as the other class divisions depended on the length of the cloacal canal. The members of the workshop accepted that the classification would not be the final word on the issue, and indeed it is not.

It is well accepted that the Wingspread classification has not been fully endorsed and used within the surgical practice as it is based on anatomical principles [71]. Its important concept of a spectrum of disease are frequently alluded to and it is used to classify newly identified rarer anomalies such as translevator anal anomalies with cutaneous fistulae passing deep to the scrotum [72]. Yet even a perfunctory review of the literature reveals the ongoing use of the original Stephens, International and Wingspread classifications. This confusion has led to heated discussion on the need for even more classifications.

Peña argues that the terms "low", "intermediate" and "high" are arbitrary and not based on outcome,

Imperforate Penis
Fig. 8.3 Anterior "ectopic" anus or perineal fistula

therapeutic management and prognosis. He further argues that other classification systems overcomplicate the issue leading to misdiagnosis and unnecessary surgery. Peñas classification is built on the concept of high and low lesions and their requirement for colostomy or not, and hence the primary principle is the management algorithm in the neonate. He argues that his classification is based on the anatomical defects and how they correlate with surgical management (Table 8.10).

A brief discussion on the subtypes on Peñas classification is necessary so that they can be compared to the other classification types. Male defects will be discussed initially. Cutaneous perineal fistula is the simplest ARM and has the lowest part of the rectum opening anterior to the sphincter. This can present in several manifestations in the male, which can cause confusion. In general, a midline fistula can appear

Table 8.10 Peña's classification



Perineal (cutaneous) fistula

Perineal (Cutaneous) fistula

Rectourethral fistula



Vestibular fistula

Rectovesical fistula

Persistent Cloaca

Imperforate anus without fistula

Imperforate anus without fistula

Rectal atresia

Rectal atresia

anywhere from the base of the penis to the midline raphe to just anterior to the centre of the sphincter. The anal membrane is also included in this group (Figs. 8.4 and 8.5).

Rectourethral fistula describes the rectum connecting to the urethra. The fistula most commonly enters the bulbar urethra, but can also enter the prostatic urethra. An important anatomical feature in the rectourethral fistula is the common wall between the fistula and the urethra. Rectovesical fistula involves the rectum opening into the bladder neck above the sphincter and bladder neck. On examination, the

Cattle Bladder Rectal Examination
Fig. 8.4 Low anorectal lesion with fistula in the scrotum
Imperforated Anus With Scrotal Fistula
Fig. 8.5 Perineal fistula in a boy with probe in situ

perineum is flat. The sacrum and pelvis can appear dysmorphic or underdeveloped (Fig. 8.6).

High imperforate anus without fistula implies that the rectum ends blindly at the level of the bulbar urethra without a fistula. ARM without fistula occurs in 5% equally in both males and females and is an uncommon presentation in the normal population. However, 50-95% of patients have trisomy 21 and the others tend to suffer from syndromes such as Apert [73,74].

Rectal atresia is a rare condition that occurs in 1% of all cases, although it is common in regions of

Hymen Imperforate
Fig. 8.6 High lesion in the male with flat perineum
Anal Atresia With High Lesion
Fig. 8.7 Imperforate anus with anterior fistula

southern India. It is frequently misdiagnosed due to the normal external appearance of the anus. The atresia lies approximately 1-2 cm above the perineum. There can be a thick fibrous band separating the rectum from the anus or a thin membrane with a small pinhole opening.

Female defects consist of several subtypes such as the cutaneous perineal fistula, which has an opening anterior to the sphincter and posterior to the introi-tus (Fig. 8.7). The vestibular fistula enters the vestibule superficial to the hymen. The vagina and the rectum contain a common wall and the fistula is of variable length. The opening can be difficult to see and requires careful inspection (Fig. 8.8).

Cloacal anomalies are a separate, complex, wide variety of malformations. Cloaca is derived from the Latin term for sewer or latrine and is defined as a common channel for the opening of the rectum, vagina and urinary systems. It is extremely important that it is correctly identified prior to definitive surgery. On examination of the perineum a single orifice is identified. The size of the introitus is smaller than in the normal female in most cases. Of note, the longer the common channel, the higher the defect and the more complex the lesions. Multiple subtypes of cloacal anomalies have been described and a full description of the cloacal anomaly is available in Chap. 10.

Peña argues that unusual and uncommon presentations should be viewed as complex malformations that require an individualised approach to each pa

Vaginas Malformation

tient; hence, no generalised guidelines can be created [74].

In reality, whether one adheres strictly to the Wingspread or Peñas classification was a matter of personal choice. From a practical point of view, Pe-ña's classification allowed a concise and appropriate clinical management structure. The Wingspread classification allowed the anatomical detail to be further elucidated. All descriptions of ARM require a detailed anatomical description of the lesion in order to illustrate the defect and allow comparisons between centres.

In May 2005 an international congress for the development of standards for the classification, treatment and follow up of ARM took place in Kricken-beck Castle in Westphalia, Germany. At this meeting the need for a new, unifying, international classification system that enabled everyone to talk the same language was quite clear. Thus was born the new standards for diagnostic procedures international classification system "Krickenbeck" (Table 8.11) [75]. This new classification system was reached by consensus within the symposium. It does not focus on anatomical or embryological features or on imaging. It is divided into two main groups "major clinical groups" and "rare/regional variants" and is based on frequency of occurrence and allows management outcomes to be measured. The addition of the "rare/ regional variants" allows lesions that are less common in the Western world yet quite common in India and

Table 8.11 Standards for diagnostic procedures: International Classification (Krickenbeck) [69]

Major clinical groups

Perineal (cutaneous) fistula Rectourethral fistula Bulbar Prostatic

Rectovesical fistula Vestibular fistula Cloaca No fistula Anal stenosis

Rare/regional variants

Pouch Colon Rectal atresia/stenosis Rectovaginal fistula H type fistula Others

the Far East to be included. For example, the H-type fistula, where together with a normally placed anal canal there is a fistulous communication between the anorectum and the genital tract, has an incidence of 3% in Finland but is found more commonly in India [76]. We accept that cloacae are uncommon, but due to the significant impact of the potential errors from an incorrect initial diagnosis it has been placed in the major group. Also, despite the controversy over anal stenosis, the symposium agreed to include it in the major group.

Beside the new international "Krickenbeck" standards for diagnostic procedures, an international grouping of surgical procedures for follow was developed at the Krickenbeck meeting (Table 8.12). This second standardisation seemed to be necessary to make the different surgical procedures comparable with each other. Perineal (cutaneous) or ano-vestibular fistulas could be operated either by a perineal operation or by an anterior sagittal approach (former Pott's procedure). The PSARP technique is used for prostatic and bulbar or recto-vestibular fistulas. To be able to compare the results of the different operations with the results of other authors, not only the type of the fistula or malformation has to be compared but also the type of the operation used. One should always keep in mind, that the postoperative results after the repair of anorectal malformations are strongly correlated to the extension of intraoperative mobilisation of the fistula and the blind pouch. This can be determined by the new international classifications for the diagnosis, the procedures and the new follow up scooring for postoperative results (see Chaps. 25 and 27).

It is therefore, envisaged that the new three Krick-enbeck classifications will enable comparable follow up of patients with anorectal malformations.

Table 8.12 International grouping (Krickenbeck) of surgical procedures for follow up [75]

Operative procedures

• Perineal operation

• Anterior sagittal approach

• Sacroperineal procedure

• Abdominosacroperineal pull-through

• Abdominoperineal pull-through

• Laparoscopic-assisted pull-through

Associated conditions

• Sacral anomalies

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  • phillipp luft
    What is anul membrane?
    7 months ago

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