imperforate ani

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CLINICAL SCIENCE SESSION

IMPERFORATE ANUS

Diajukan untuk memenuhi tugas Program Pendidikan Profesi Dokter (P3D)

SMF Ilmu Bedah

Disusun oleh:

Cyndee Bayu Naga Dewata 12010011044

Khairuli Amri 12010011028Ilham Rizky Ernawan 12100100908

Partisipan :

Dety Nur Rachmawati 12010011021

Marry Nadya Elmiera 12010011007

Eva Noviani Lestari 12010011035

Dini Paramita Defrin 12010011068

Preseptor:

Liza Nursanti dr.,Sp.B

SMF ILMU BEDAH

PROGRAM PENDIDIKAN PROFESI DOKTER

FAKULTAS KEDOKTERAN

UNIVERSITAS ISLAM BANDUNG

RS AL-ISLAM BANDUNG

2011


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CHAPTER I

PREFACE

1.1 BackgroundAnorectal malformations include a wide spectrum of defects in the

development of the lowest portion of the intestinal and urogenital tracts. Many

children with these malformations are said to have an imperforate anus because

they have no opening where the anus should be. Although the term mayaccurately describe a child's outward appearance, it often belies the true

complexity of the malformation beneath. When a malformation of the anus is

present, the muscles and nerves associated with the anus often have a similar

degree of malformation. The spine and urogenital tract may also be involved

The position and nature of these malformations made repair difficult for early

surgeons. The affected organs are located deep in the pelvis and are not well

visualized through abdominal incisions. Traditional surgical dictum did not allow

for division of the posterior midline because this division of the muscle was

believed, somewhat erroneously, to cause incontinence in the child. Therefore,

surgeons approached these malformations using a combined abdominal, sacral,

and perineal approach, with limited visibility. Such approaches have put

continence, and surrounding genitourinary structures, at greater risk than simply

cutting sphincter muscles because of the difficulty of adequately visualizing the

malformation through limited incisions. This principle was central to the

development of the surgical techniques currently used to repair these

malformations.

In 1982, Pea et al reported the results of the use of a posterior sagittal

surgical repair approach.[1] Pea et al used the traditional approach with a sacral

incision and made the incisions progressively larger in an attempt to adequately

visualize the anatomy. Eventually, the entire posterior sagittal plane was opened,


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CHAPTER II

LITERATURE REVIEW

2.1 Embriology of Digestive

As a result of cephalocaudal and lateral folding of the embryo, a portion of

the endoderm-lined yolk sac cavity is incorporated into the embryo to form the

primitive gut. Two other portions of the endoderm-lined cavity, the yolk sac and

the allantois, remain outside the embryo (Fig. 13.1, AD). In the cephalic and

caudal parts of the embryo, the primitive gut forms a blind-ending tube, the

foregut and hindgut, respectively. The middle part, the midgut, remains

temporally connected to the yolk sac by means of the vitelline duct, or yolk stalk

(Fig. 13.1D). Development of the primitive gut and its derivatives is usually

discussed in four sections:

1. The pharyngeal gut, or pharynx, extends from the buccopharyngeal

membrane to the tracheobronchial diverticulum (Fig. 13.1D); since this

section is particularly important for development of the head and neck, it isdiscussed in Chapter 15.

2. The foregut lies caudal to the pharyngeal tube and extends as far caudally as

the liver outgrowth.

3. The midgut begins caudal to the liver bud and extends to the junction of the

right two-thirds and left third of the transverse colon in the adult.

4. The hindgut extends from the left third of the transverse colon to the cloacal

membrane (Fig. 13.1). Endoderm forms the epithelial lining of the digestive

tract and gives rise to the parenchyma of glands, such as the liver and

pancreas. Muscle, connective tissue, and peritoneal components of the wall of

the gut are derived from splanchnic mesoderm.


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Figure 2.2 Diagrams of the mid- and hindgut regions. The morphogen sonic

hedgehog (SHH) is secreted by gut endoderm and induces a nested expression of

HOX genes in surrounding mesoderm.HOX expression then initiates a cascade of

genes that instruct gut endoderm to differentiate into its regional identities.

Signaling between the two tissues is an example of an epithelial-mesenchymal

interaction.

The hindgut gives rise to the region from the distal third of the transverse

colon to the upper part of the anal canal; the distal part of the anal canal originates

from ectoderm. The hindgut enters the posterior region of the cloaca (future

anorectal canal), and the allantois enters the anterior region (future urogenital

sinus). Breakdown of the cloacal membrane covering this area provides

communication to the exterior for the anus and urogenital sinus. Abnormalities in

the size of the posterior region of the cloaca shift the entrance of the anus

anteriorly, causing rectovaginal and rectourethral fistulas and atresias (Figs. 2.3

and 2.4).


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Figure 2.3 Cloacal region in embryos at successive stages of development.A. The hindgut enters the posterior portion of the cloaca, the future anorectal

canal; the allantois enters the anterior portion, the future urogenital sinus. The

urorectal septum is formed by merging of the mesoderm covering the allantois

and the yolk sac (Fig. 13.1D). The cloacal membrane, which forms the ventral

boundary of the cloaca, is composed of ectoderm and endoderm.

B. As caudal folding of the embryo continues, the urorectal septum moves closer

to the cloacal membrane, although it never contacts this structure.

C. Lengthening of the genital tubercle pulls the urogenital portion of the cloaca

anteriorly; breakdown of the cloacal membrane creates an opening for the hindgut

and one for the urogenital sinus. The tip of the urorectal septum forms the perineal

body.

Figure 2.4 Abnormal development of the cloacal region at 7 weeks.


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A. High urorectal fistula resulting from a large decrease in size of the posterior

portion of the cloaca and cloacal membrane that shifts the opening of the hindgut

further anteriorly.

B. Imperforate anus. The anal canal fails to recanalize, leaving a diaphragm

between the upper and lower portions of the anal canal.

2.2 Anatomy of Anorectal

The rectum is approximately 12 to 15 cm in length. Three distinct

submucosal folds, the valves of Houston, extend into the rectal lumen. Posteriorly,

the presacral fascia separates the rectum from the presacral venous plexus and the

pelvic nerves. At S4, the rectosacral fascia (Waldeyer's fascia) extends forward

and downward and attaches to the fascia propria at the anorectal junction.

Anteriorly, Denonvilliers' fascia separates the rectum from the prostate and

seminal vesicles in men and from the vagina in women. The lateral ligaments

support the lower rectum. The surgical anal canal measures 2 to 4 cm in length

and is generally longer in men than in women. It begins at the anorectal junction

and terminates at the anal verge. The dentate or pectinate line marks the transitionpoint between columnar rectal mucosa and squamous anoderm. The 1 to 2 cm of

mucosa just proximal to the dentate line shares histologic characteristics of

columnar, cuboidal, and squamous epithelium and is referred to as the anal

transition zone. The dentate line is surrounded by longitudinal mucosal folds,

known as the columns of Morgagni, into which the anal crypts empty.


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Anorectal Vascular Supply begin the superior rectal artery arises from the

terminal branch of the inferior mesenteric artery and supplies the upper rectum.

The middle rectal artery arises from the internal iliac; the presence and size of

these arteries are highly variable. The inferior rectal artery arises from the internal

pudendal artery, which is a branch of the internal iliac artery. A rich network of

collaterals connects the terminal arterioles of each of these arteries, thus making

the rectum relatively resistant to ischemia (Fig. 2.7)

Figure 2.7 Arterial Supply of the rectum and anal canal

The venous drainage of the rectum parallels the arterial supply. The superior

rectal vein drains into the portal system via the inferior mesenteric vein. The

middle rectal veindrains into the internal iliac vein. The inferior rectal veindrains

into the internal pudendal vein, and subsequently into the internal iliac vein. A

submucosal plexus deep to the columns of Morgagni forms the hemorrhoidal

plexusand drains into all three veins.


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Lymphatic drainage of the rectum parallels the vascular supply. Lymphatic

channels in the upper and middle rectum drain superiorly into the inferior

mesenteric lymph nodes. Lymphatic channels in the lower rectum drain both

superiorly into the inferior mesenteric lymph nodes and laterally into the internal

iliac lymph nodes. The anal canal has a more complex pattern of lymphatic

drainage. Proximal to the dentate line, lymph drains into both the inferior

mesenteric lymph nodes and the internal iliac lymph nodes. Distal to the dentate

line, lymph primarily drains into the inguinal lymph nodes, but can also drain into

the inferior mesenteric lymph nodes and internal iliac lymph nodes.

Both sympathetic and parasympathetic nerves innervate the anorectum.

Sympathetic nerve fibers are derived from L1-L3 and join the preaortic plexus.

The preaortic nerve fibers then extend below the aorta to form the hypogastric

plexus, which subsequently joins the parasympathetic fibers to form the pelvic

plexus. Parasympathetic nerve fibers are known as the nervi erigentes and

originate from S2-S4. These fibers join the sympathetic fibers to form the pelvic

plexus. Sympathetic and parasympathetic fibers then supply the anorectum and

adjacent urogenital organs.

The internal anal sphincter is innervated by sympathetic and

parasympathetic nerve fibers; both types of fibers inhibit sphincter contraction.

The external anal sphincter and puborectalis muscles are innervated by the

inferior rectal branch of the internal pudendal nerve. The levator ani receives

innervation from both the internal pudendal nerve and direct branches of S3 to

S5. Sensory innervation to the anal canal is provided by the inferior rectal branch

of the pudendal nerve. While the rectum is relatively insensate, the anal canal

below the dentate line is sensate


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CHAPTER III

IMPERFORATE ANUS

3.1 Definition

Anorektal malformation of defects in the development of the lowest

portion of the intestinal. Figure Although the precise embryologic defect that

causes anorectal malformations has not been determined, cloacal membrane

formation and subsequent breakdown into urogenital and anal openings should

occur by 8 weeks' gestation. Defects in the formation or shape of the posterior

urorectal septum account for many of the described abnormalities of imperforate

anus. Mllerian ducts appear after this critical period; how they are incorporated

into this development is unclear.

3.3 Incidence and epidemologi

United States Anorectal malformations occur in approximately 1 newborn

per 5000 live births. Mortality/Morbidity Anorectal and urogenital malformations

are rarely fatal, although some associated anomalies (cardiac, renal) can be life

threatening. Intestinal perforation or postoperative septic complications in a

newborn with imperforate anus can result in mortality or severe morbidity. no

known racial and no known sex predilection has been reported.

3.4 Clinical Manifestation

In males, the testicles must be palpated in the scrotum. The perineum is

then examined. Perineal fistulas are diagnosed upon discovery of openings on the

perineum, meconium or mucus in a small strip running up into the scrotal median

raphe, a perineal groove, or a bucket-handle malformation in the anal dimple skin.

If no opening is present, urine is obtained for study, and the child is observed for

24 hours.


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In females, a perineal fistula can be directly identified as a small opening

on the perineum. If none is present, the labia are separated to search for a

vestibular fistula. A fourchette fistula is a type of vestibular fistula that straddles

the spectrum of malformation between perineal and vestibular; it is characterized

by wet mucosa of the vestibule anteriorly and a dry anoderm posteriorly at the

junction of the vestibule and perineum

Imperforate Anus And Associated Malformation

If the child has a normal urethra and no vestibular fistula, she may haveimperforate anus without fistula. If she appears to have trisomy 21, the likelihood

increases that she does not have a fistula. Girls with normal urethra and no visible

fistula are observed for 24 hours to allow a perineal fistula to present before

operation is required. This waiting period is beneficial in differentiating between

children with perineal fistula who may be effectively treated using only a minimal

anoplasty from those who require colostomy with further evaluation using distal

colostography. Examples of colostography findings are shown in the images

below.

Cardiovascular malformations occur in 12-22% of patients. The most

common lesions are tetralogy of Fallot and ventricular septal defects.

Transposition of the great arteries andhypoplastic left heart syndrome have been

reported but are rare.

Many GI malformations have been described in association withimperforate anus. As many as 10% of patients have tracheoesophageal

abnormalities. Duodenal obstruction due to annular pancreas or duodenal atresia

occurs in a small percentage of patients. Malrotation with Ladd bands that causes

obstruction has also been described.Hirschsprung disease has been well described

in association with imperforate anus, although the incidence of this combined

condition is unknown. Constipation is common.
http://emedicine.medscape.com/article/163628-overviewhttp://emedicine.medscape.com/article/892980-overviewhttp://emedicine.medscape.com/article/900574-overviewhttp://emedicine.medscape.com/article/890196-overviewhttp://emedicine.medscape.com/article/929733-overviewhttp://emedicine.medscape.com/article/929733-overviewhttp://emedicine.medscape.com/article/890196-overviewhttp://emedicine.medscape.com/article/900574-overviewhttp://emedicine.medscape.com/article/892980-overviewhttp://emedicine.medscape.com/article/163628-overview


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The association of imperforate anus and vertebral anomalies has been

recognized for many years. Patients with high lesions have an increased risk of

this association. Lumbosacral anomalies predominate and occur in approximately

one third of patients with imperforate anus.

The frequency of spinal dysraphism (evaluated with ultrasonography or

MRI) had been thought to increase with the severity of the lesion, with higher

malformations having greater frequency than lower malformations. Several

studies have disputed this and have even shown higher incidence of spinal

malformations in children with low malformations. The most common type of

dysraphism is tethered spinal cord, which is present in as many as 35% of

patients. The normal spinal cord terminates between the first and second lumbar

vertebral bodies. In patients with a tethered spinal cord, the cord ends lower in the

lumbar spine. Cord lipomas and syringohydromyelia are also common. All

lumbosacral spinal malformations negatively affect the child's prognosis with

respect to urinary and fecal incontinence.

Currarino described a triad of sacral defect, presacral mass, and

imperforate anus.[2] All patients with an anorectal malformation must be screened

for these vertebral abnormalities in the newborn period using sacral radiography

and lumbosacral spinal ultrasonography. As many as one half of patients with

anorectal malformations have urologic abnormalities. Urinary anomalies are more

common in patients with more complex lesions. Improved imaging studies have

provided the ability to document an increased range of abnormalities. Mild

hydronephrosis is the most common abnormal ultrasonography finding.

Vesicoureteric reflux is also a frequent finding, followed by renal agenesis and

dysplasia.Cryptorchidism reportedly occurs in 3-19% of males.

Vaginal and uterine abnormalities are common. Bicornate uterus and

uterus didelphys occur in 35% of female patients with imperforate anus. A vaginal

septum is the most common vaginal abnormality and is seen in as many as one

half of girls born with a cloacal malformation. Vaginal duplication and agenesis
http://emedicine.medscape.com/article/1017420-overviewhttp://emedicine.medscape.com/article/1017420-overview


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have also been reported. Vaginal agenesis may be associated with ipsilateral

absent ovary and kidney.

3.5 Classification

Pena proposed a classification system that specifically describes the

location of the fistulous opening. In males the fistula may communicate with:

A. The perineum (cutaneous perineal fistula).

B. The lowest portion of the posterior urethra (rectourethral bulbar fistula).

C. The upper portion of the posterior urethra (rectourethral prostatic fistula).

D. The bladder neck (rectovesicular fistula).


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Figure 3.1 Classification of anorectal malformation

In females, the urethra may open onto the perineum between the female

genitalia and the center of the sphincter (cutaneous perineal fistula), or into the

vestibule of the vagina (vestibular fistula). In both sexes, the rectum may end in a

completely blind fashion (imperorate anus without fistula). In rare cases, patients

may have a normal anal canal, yet there may be total atresia or severe stenosis of

the rectum.

3.5 Diagnosis


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Patients with Imperforate anus are usually stable, and the diagnosis is

readily apparent. Despite the obstruction, the abdomen is initially not distended,

and there is rarely any urgency to intervene.

D

Figure 3.2 Distal colostogram, posteroanterior view. The initial phase of

augmented-pressure distal colostography aims to determine where the colostomy

was placed in the colon and how much colon is available for pull-through, without

taking down the colostomy.

The principles of management center around diagnosing the type of defect

that is present (high versus low), and evaluating the presence of associated

anomalies. All patients should therefore have an orogastric tube placed and be

monitored for the appearance of meconium in or around the perineum, or in the

urine. Investigation for associated defects should include:

A. Ultrasound of the abdomen to assess for the presence of urinary tractanomalies.

B. Echocardiogram.C. Spinal radiographs. An ultrasound of the spine should be performed to look

for the presence of a tethered cord.

D. To further classify the location of the fistula as either high or low, a lateralabdominal radiograph can be obtained with a radiopaque marker on the
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perineum. By placing the infant in the inverted position, the distance between

the most distal extent of air in the rectum and the perineal surface can be

measured. However, this study is imprecise.

Figure 3.3 Distal colostogram, lateral view. This image shows the second phase

of distal colostography, in which the patient is placed in the lateral position. Aradio-opaque marker is clearly visible in the lower right side of the image,

marking the muscle complex on the skin. This image shows that the rectal pouch

joins the urinary tract at the level of the bulbar urethra, a relatively common

malformation in boys.

3.5 Treatment

The surgical management of infants with imperforate anus is determinedby the anatomic defect. It may take up to 24 hours before the presence of a fistula

on the skin is noted, and thus it is important to observe the neonate for some time

before definitive surgery is undertaken. In general, when a low lesion is present,

only a perineal operation is required, without a colostomy. Infants with a high

lesion require a colostomy in the newborn period, followed by a pull-through

procedure at approximately 2 months of age.
http://refimgshow%282%29/


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Figure 3.4 Prone Position

When a persistent cloaca is present, the urinary tract needs to be carefully

evaluated at the time of colostomy formation to ensure that normal emptying can

occur, and to determine whether the bladder needs to be drained by means of a

vesicostomy. If there is any doubt about the type of lesion, it is safer to perform a

colostomy rather than jeopardize the infant's long-term chances for continence by

performing an injudicious perineal operation. The type of pull-through procedure

favored by most pediatric surgeons today is the posterior sagittal anorectoplasty

(PSARP) procedure, as described by Pea and DeVries. This involves dividing

the levator ani and external sphincter complex in the midline posteriorly, and

bringing down the rectum after sufficient length is achieved.

Figure 3.5 Electrical stimulator probe used to show sphincteric contractions.

Used with electrical stimulator
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.

Figure 3.6 Recommended colostomy with divided stomas, the proximal stoma in

the descending colon.
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Figure 3.6 Algorithm for treatment of newborn boy and female with anorectal

malformation

The type of pull-through procedure favored by most pediatric surgeons today is

the posterior sagittal anorectoplasty (PSARP) procedure, as described by Pea and

DeVries. This involves dividing the levator ani and external sphincter complex in the

midline posteriorly, and bringing down the rectum after sufficient length is achieved. Themuscles are then reconstructed and sutured to the rectum. The outcome of 1192 patients

who had undergone this procedure was recently reviewed by Pea and Hong. Seventy-

five percent of patients were found to have voluntary bowel movements, and nearly 40%

were considered totally continent. As a rule, patients with high lesions demonstrate an

increased incidence of incontinence, whereas those with low lesions are more likely to be

constipated.


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Figure 3.7 posterior sagittal anorectoplasty


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Post operation surgery complication is constipation that the major of the

complication which is happen to the patien that have a surgery of anorectal

malformation

3.6 Prognosis

Patients with a low opening has an excellent outcomes. Almost 75%

patient with low opening anorectal malformation become soiling, and later the

soiling will relieve by it self. Almost 25% of patient have a fecal incontinence and

should have a gut toilet management.

Patients with a high opening (more than 3cm) is have a bad outcomes

which functionally.

Pasien-pasien dengan MAR letak rendah seperti rectoperineal fistula

mempunyai excellent outcomes,juga pada vestibular fistula.Hampir 75% pasie-pasien

dengan anorectal malformations sering terjadi soiling.Episode dari soiling ini sering

berhubungan dengan konstipasi.Dengan terapi yang baik kejadian soiling biasanya

berkurang sampai menghilang.25% pasien mempunyai fekal inkontinens dan harus

mendapat managemen pembersihan usus.

Pencernaan harus dievaluasi ketika anak sudah berusia lebih dari 3 tahun.Pada

kasus ini maka diperlukan laxantive,special diet,dan enema. Pasien dengan fistula

rektourethral dan normal sacrum juga mempunyai out come yang baik.Hampir 80%

pasien dengan persisten kloaka dan normal sacrum mempunyai pencernaan yang

terkontrol.Pasien dengan MAR yang letak sangat tinggi seperti fistula bladder neck pada

pasien laki-laki mempunyai out come yang jelek,meskipun dengan sacrum yang normal.


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Sakrum sendiri dapat menjadi predictor yang baik entuk menilai out

come.Pasien dengan hipodevelopmental sacrum sering mengalami masalah inkontinens

dan juga keadaan ini sering disertai dengan masalah-masalah di spinalnya.Ketika defek

spesifik tsb sudah ditemukan maka secara fungsional prognosis atas pasien tersebut

dapat diprediksi.

Jika pasien mempunyai defek dengan prognosis yang kurang baik seperti high

cloaca terutama tingginya lebih dari 3 cm;bladder neck fistula,maka keluarga perlu di

informed concent bahwa pasien nantinya memerlukan program bowel

managemen,biasanya saat berusia 3-4 tahun.

imperforate ani

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