ANORECTAL MALFORMATIONS OGUNTADE BABATUNDE FINALS

Outline Introduction Brief anatomy of the anal canal Epidemiology Aetiology Classification -----associated co- malformations Management conclusion

Introduction Anorectal malformations comprise a wide spectrum of diseases, which can affect males and female,and can involve the distal anus and rectum as well as the urinary and genital tracts.

Brief anatomy

anatomy The rectum and the proximal half of the anus, which are endodermal in origin, are developed from the dorsal pan of the cloaca while the distal half of the anus, which is Ectodermal in origin, arises from the anal pit or proctodeum. The cloaca is the blind terminal portion of the hindgut into Which the allantois opens. A urorectal septum arises from the angle between the opening of the allantois and the cloaca and grows caudally to fuse with the blind end thus dividing the dorsal portion, the rectum, from the ventral portion of the urogenital sinus.

anatomy The rectal portion of the blind end of the cloaca is the anal membrane separating the proximal portion of the anus from the ectodermal depression, the proctodeum, which later becomes the distal portion of the anus. The anal membrane lies at the level of the anal valves and breaks down by the eighth week to establish continuity of the lumen.

Epidermiology They occur in approximately 1 in 5000 live births. males are at a greater risks than females

aetiology The etiology of such malformations remains unclear and is likely multifactorial. Genetics Increased risk in trisomy 21 (Down's syndrome)

Classification Anorectal anomalies can classified has either High(40%) or, Low(60%) . This depends on whether the malformation is above or below the level of the puborectalis muscle. Some has also included intermediate.

Prognosis(outlook) is good LOW MALFORMATIONS Termination or malformation of bowel below the pelvic floor. continence is maintained in 90% of the cases, easy to Diagnose Simple to treat Prognosis(outlook) is good They include Covered anus Ectopic anus Membranous stenosis/persistent anal memb Anal stenosis Anal agenesis

Covered anus In this type, the anal canal and sphincters are normally developed, but the anal orifice is covered by skin arising from the excessive fusion of the anal tubercles and lateral genital folds.

Ectopic anus The anus opens in an ectopic site usually in the vulva, vestibule, lower vagina or the perineum. It is caused by failure of the anal opening to "migrate" posteriorly to its proper position. The sphincters are normally developed. Ectopic anus is more common in females.

Anal Stenosis i.e. microscopic anus There is a minute opening that can be seen if examined carefully

Persistent Anal Membrane The rectum and the anus are normally developed but there is a complete or incomplete diaphragm in the anal canal at the level of the anal valves (pectinate line). Anus is normally sited covered with a thin membrane that bulges with retained meconium

Anal agenesis It results from non-development of the anal pit and excessive fusion of the anal tubercles.

High anomalies(40 %) Anorectal agenesis Rectal atresia Cloaca

Anorectal agenesis Rare; blind rectal pouch lies just above the pelvic floor In ♂ anterior aspect attached to the bladder & often there is a rectovesical fistula or rectourethral fistula (manifested by passage of gas or meconium in the urine) or perineal fistula In♀ fistula to the posterior fornix >> rectovestibular (or rectovaginal) low RVF easy to correct post op. Function is good high RVF difficult to correct post op function is poor

Rectal atresia Rare too, Anal canal is normal but ends blindly at the level of pelvic floor & the rectum also ends blindly above the pelvic floor without a fistulas opening.

Cloaca Occurs only in ♀ Bowel, urinary & genital tracts all open into a common wide cavity Commonly associated with other developmental abnormalities e.g. tracheoesophagial fistula

Associated anomalies GI anomalies esophageal atresia, intestinal atresia Skeletal abnormalities; sacral agenesis(40%) of patients with anomaly urinary abnormalities(30%); megaureter, hydronephrosis malformation of the kidneys can also occur in about a third of pts Genital anomalies; Congenital heart lesions Nervous system anomalies( tethered cord,stenosis of the dural sac, narrow spinal cord)

Approach History >>> the systems involved Examination >>> DDx Investigation >>> Dx Management

history Failure to pass meconium within the 1st 24 hours of life. Patients with anterior ectopic anus may present in childhood or in adulthood. These patients have lifelong histories of constipation and painful defecation and usually have required laxatives or enemas for management

Examination Careful examinations of the perineum, vulva,vagaina,scrotum,and penis for abnormal openings. Bulge of anal membrane should be looked for, a flat perineum without an anal dimple, suggests high anom, while an anal dimple suggests otherwise. The urine should be examine for meconium.other congenital anomlies should be looked for.

Some can also present with features of obstruction; late vomiting, distended abdomen,

Examination Low High Bucket handle defect Flat bottom Short sacrum Gas/meconium from perineum Perineal fistula if skin bridge between vestibule and fistula. Anterior ectopic anus i.e. normal sized anus surrounded by normal muscle. Urine free of meconium (NB average of 20 hrs for meconium to appear in urine). High Flat bottom Short sacrum Little muscle contraction Meconium per urethra Rectovestibular fistula if within mucosal margin of the vestibule. Sphincter located close to the scrotum or bifid scrotum often associated with a Prostatic Fistula. Cloacae are often missed if urethral opening is not identified in female with a “recto-vaginal” fistula. Furthermore, cloacae often have small openings and may be a cause of referral for ambiguous genitalia.

Investigation Very Important to: 1. Exclude other anomalies!! 2.Determine whether abnormality is high or low!!

Investigation Associated abnormality Spinal ultrasound, Spinal x-ray "V" Vertebral Abnormality (butterfly vertebrae, hemi-vertebrae) Cardiac ECHO "C" Cardiac, Heart Abnormality Cardiac ECHO (VSD, ASD, PDA) Renal ultrasound, Voiding cysto-urethra-gram (VCUG) "R" Renal, Kidney abnormality (solitary kidney, horse shoe kidney) Physical examination "TE" tracheoesophogeal abnormality (TEF) Physical examination, x-rays "L" Limb deformity

1) X-ray (Invertogram) with a metal button or a coin strapped to the site of the anus or a metal bougie inserted into the blind anal canal Infant is held upside down for 3-4 minutes Then radiograph in the inverted lateral position ( both the greater trochanters should be on the same line) The gas in the rectum will rise to the top indicates the distance between the site of the metal indicator and the blind end of the rectum >>> if the distance > 2.5 cm, the abnormality is high!!

if the rectum ends above the PC line (pubococcygeal line = from the symphysis pubis to the last vertebra), the abnormality is Low & vise versa or according to ischeal line (between ant.- sup. Iliac spines). When to be done? Although it is a useful method, sometimes vitiated by a plug of meconium in the rectum causing an apparent gap far in excess of that actually present. So, it may be necessary to wait until the baby is 24 hrs old before rectal gas appears

Metal button PC line gas in the rectum

IVU and voiding cystourethrogram to find out urinary abnormalities USS, CT, MRI. Gives a clear definition of the end of the bowel and any associated anomalies Also, a urine culture may be done (presence of proteus or psuedomonas may suggest meconium

Treatment Low Anomalies The aim of treatment is to restore the anus to its normal anatomical position within the external sphincter. The defects are treated at birth.

1)Covered anus: The track should be opened by scissors Followed by routine dilatation of the anus (for about 3 months) 2)Ectopic anus: Plastic “cut-back”/midline operation and subsequent dilatation 3)Stenosed anus: Regular dilatation 4) Anal Membrane– incision and dilatation

high Whether there is obstruction or not, a sigmoid colostomy is done first. At 3-6 months or when the baby is 9kg, the definitive operation of posterior sagittal anorectoplasty is PSARP done. “Pull -through” operation

complications 1. Incontinence especially in high anomalies is a problem. 2. Stenosis or stricture at the muco- cutaneous junction after abdominal pulbthrough may occur. Dilatation is performed. 3. Prolapse of mucosa may occur, and must be excised.

Prognosis In high % of cases, imperforate anus is associated with other congenital abnormalities especially of the urinary organs & nearly 50% of deaths in cases of imperforate anus are due to other malformations

Pull-through operation/Posterior sagittal anorectoplasty(PSARP) Lower bowel is mobilized New passage is created through the pelvic floor by passing a pair of curved forceps & through it, keeping close to the urethra, to the site of the future anus. This is dilated by Hegar’s dilator so that the bowel can be pulled down and its mucosa stitched to the skin of the newly formed anus. Daily dilatation will be required for at least 3 mo. after the operation and it may be necessary for years.

PSARP Published by Dr. Albeto Peña >> It is assumed that the innervation to the sphincter mechanism is paired and meets in the midline. The PSARP dissection is along the midline providing excellent exposure with minimal trauma to nerves and musculature. It involves: • Stimulation of muscles to demonstrate the midline and sphincter • Posterior sagittal incision - length depends on severity of abnormality and required extent of dissection • Rectum identified. Abdominal approach may be required in addition in 10% of males and 40% of cloacae • Rectum dissected • Separation from genitourinary tract • Repositioning the neoanus within the sphincteric mechanism

Position for PSARP

Incision in PSARP

Posterior sagittal repair of a rectovestibular fistula.

IN a Summary 1 opening >>> Cloaca 2 openings >>> anorectal agenesis with rectovaginal fistula 3 openings >>> ectopic anus, stenosed anus, membranous anus, rectal atresia or even normal anus!!! The most important investigation is the invertogram It is very important to rule out other anomalies The best & the newest operation is PSARP