Malformasi Anorektal. Anorectal malformations comprise a wide spectrum of diseases, which can affect boys and girls, and involve the distal anus and rectum as well as the urinary. Anorectal malformations (ARMs) are among the more frequent congenital anomalies encountered in paediatric surgery, with an estimated incidence ranging.
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Anorectal malformations ARMs are among the more frequent congenital anomalies encountered in paediatric surgery, with malformasu estimated incidence ranging between 1 in and 1 in live births.
Antenatal diagnosis of an isolated ARM is rare. Most cases are diagnosed in the early neonatal period. There is a wide spectrum of presentation ranging from low anomalies with perineal fistula having simple management to high anomalies with complex management.
Advances in the imaging techniques with improvement in knowledge of the embryology, anatomy and physiology of ARM cases have refined diagnosis and initial management.
There has been marked improvement in survival of such patient over the last century. But still the fecal and urinary incontinence can occur even with an excellent anatomic repair, mainly due to associated problems.
There has been a paradigm shift in approach to these patients which involves holistic approach to the syndrome of Anorectal malformations with a long term goal of achievement of complete fecal and urinary continence with excellent quality of life.
Anorectal malformations ARMs are among the more frequent congenital anomalies encountered in pediatric surgery, with an estimated incidence ranging between 1 in and 1 in live births. The etiology of such malformations remains unclear and is likely multifactorial. There appears to be a low rate of association in families, but some appear to have an autosomal dominant inheritance pattern with a high incidence, as much as 1 in Chromosome 7q39 has three important loci, which are implicated for development of ARM, these include genes: There has always been a need for classifying these anomalies in order to decide the management and predict the final outcome.
The earliest classification of ARM was based on the position of the terminal bowel in relation to the levator ani or pelvic floor. To standardize the methodology for evaluation of outcome of patients with ARM Krickenbeck group came with their classification.
It comprised of three distinct elements: The Krickenbeck classification also gave equal emphasis to both constipation and soiling compared with previous scoring systems which hardly took constipation into account. Approximately, half of children with ARM have associated anomalies. Hence, the anomalies are most frequently associated with rectovesical fistula, but the major spinal anomalies are seen in all groups including those with perineal fistula. At birth, a general examination in any newborn should include the perineum.
The absence or abnormal location of the anus is generally apparent.
In the male, besides the absent anus, a note must be made of the anal pit. The fistula may be of small caliber; hence, it may take up to 24 h for it to be apparent.
The reason for this is that it takes this long for ingested gas to travel down the gut to the blind rectum. In the female child, the diagnosis rests on the appearance of the anoorektal.
Normally, there are three visible openings — the most anterior being the urethra, followed by the vagina, both of these being within the vestibule. Behind the perineal body is the anus. The presence of three openings, with the anus not being at its normal site is indicative of either a perineal fistula, formerly called the anterior perineal anus.
If the third opening is seen within the vestibule, it is a vestibular fistula. Two openings only, indicate two extremely rare clinical entities, namely a recto vaginal fistula, or a blind ending rectum with no fistula. A single opening indicates the persistent cloaca. Wangensteen and Rice first described the use of inversion radiography in to indicate the distance between the gas bubble within the terminal colon and the perineal skin. Direct measurement between the gas-filled gut and the skin of the anus by placing a radiopaque marker on the skin is made.
Subsequently, the P—C line and the I line are determined by invertography. The babies are kept in the genupectoral position for 3 min by holding their facedown with hips flexed.
Prone lateral radiographs is obtained, which is centered over the greater trochanters like in the invertogram. Ultrasonographic examination has been used to know the pouch perineal distance. It can be performed through a transperineal or infracoccygeal route. Infracoccygeal route can directly demonstrate the puborectalis as a hypoechoic U-shaped band.
The noninvasive nature and no radiation exposure are the main advantages, but it is highly observer dependent. Computer tomography CT and magnetic resonance imaging MRI of pelvis have been utilized for the direct visualization of the sphincteric muscles. These have been used for the structural evaluation of pelvic floor muscle and relation to the pouch, for both the pre- and post-operative evaluation. The exact location of fistula and relation to the pelvic floor muscle provides crucial information regarding the approach, whether a sagittal approach or an approach through abdominal route is required.
MRI and CT scans are also utilized for the assessment of structural development following different procedures for ARM and can help in comparison of outcome between different procedures. MRI is considered superior to CT scan because of excellent soft tissue characterization, multiplanar imaging, and lack of ionizing radiation.
The early management of a newborn with an anorectal anomaly is crucial. In developing countries, presentation can be delayed. This is with associated abdominal distension, dehydration and sepsis. Initial resuscitation with intravenous fluid and broad spectrum antibiotics holds the key for the final outcome in such cases.
After assessment of associated anomalies the child can be taken for a protective colostomy, followed by delayed repair later or a single staged definitive procedure can also be performed in selected cases. Management of male and females cases differ.
Malformasi Anorektal | Lokananta | Jurnal Kedokteran Meditek
Male newborns with rectoperineal fistula do not need a colostomy. The male babies with evidence of a recto-urinary tract communication should undergo fecal diversion with a colostomy.
Abdominal approach is required to get access to fistula in cases with recto-bladder neck fistula. Pouch colon also requires abdominal approach. In cases with sepsis, perforation a protective colostomy is performed in the neonatal period followed by a definitive pull-through procedure at months of age. Before the definitive operation, a pressured distal colonogram and voiding cystourethrogram should be performed to reveal the site of rectourethral fistulas.
General condition, duration of presentation and number of openings in the vestibule decide the management.
Gross abdominal distension, sepsis, or single opening persistent cloaca warrants a diversion colostomy. The most common anomaly in females is a rectovestibular and shows a normal urethra, normal vagina, and another orifice, which is the rectal fistula in the vestibule. In selected cases, a primary PSARP or a primary anterior sagittal anorectoplasty can also be performed.
In cases with common channels longer than 3 cm, it is difficult to mobilize the vagina through PSARP, and an abdominoperineal approach is required. If the distance from the vagina to the perineum is long, a bowel segment can be used to bridge the gap, preferably a segment of the colon or a vaginal switch procedure can be done in cases with bicornuate uterus.
There has been debate over single stage versus staged repair of ARM.
Single stage procedure has less morbidity, mortality at low cost. The better continence may be attributed to the better development of cerebral fibers. These cerebral cortical fibers develop in the 1 st year of life and sensations of rectal fullness are essential for these fibers to develop fully so that continence can be achieved to its maximal potential.
The other advantages of single stage repair are easier dissection in the neonatal period due to virgin tissue planes with no fibrosis due to pouchitis, no need of bowel preparation and colostomy is not usually accepted in our society. Physical and psychological stress to the parents, child and surgeon are less. Absolute contraindication for single stage repair is severe life-threatening other congenital malformations, sepsis or necrotizing enterocolitis with pneumoperitoneum, extreme prematurity and common cloacae.
The single staged repair carries a considerable risk to the urinary tract with this practice because the surgeon does not know the precise anorectal defect. The only way to definitively determine the patient’s anorectal defect is to perform a distal colostogram, which of course requires the presence of a colostomy. Without this information, an operation in the newborn period is essentially a blind perineal exploration.
The surgeon may not be able to find the rectum and may find and damage other, unexpected, structures, such as the posterior urethra, seminal vesicles, vas deferens, and ectopic ureter during the search for the rectum.
Finally, without fecal diversion, there is the risk of dehiscence and infection. These complications may compromise the ultimate functional prognosis.
Newer imaging modalities and advances in radiological technique have made it possible to exactly delineate the site of rectourethral fistula. This has tilted the balance in favor of single stage repair of appropriately selected cases, as most feared complication of single staged repair like trauma to urinary tract can be avoided. Understanding of anatomy and thus the principal of surgical repair of ARM has evolved continuously over the past century. Douglas Stephens puborectalis concept introduced in remained the basis of all surgical procedures for intermediate and high ARM.
A combination of perineal and abdominal approach was done by Rhoads et al. So Rehbein performed endorectal pull-through to avoid any damage to the pelvic innervations. In cases with rectal pouch distal to the pubococcygeal line, it was possible to divide the fistula and mobilize the rectum via the sacrococcygeal route alone without abdominal exploration.
This approach allowed surgeons to view the anatomy of these defects clearly, to repair them under direct vision, and to learn about the complex anatomic arrangement of the junction of the rectum and genitourinary tract.
Posterior sagittal anorectoplasty has become the standard of care for dealing with ARM. LAARP is not recommended for intermediate-type ARMs, because this method requires wide dissection of the rectum and may cause damage to the rectal nerves and pelvic plexus, resulting in poor bowel function. Congenital pouch colon CPC is a congenital anomaly in which whole or part of the colon is replaced by a pouch-like dilatation that communicates distally with the urogenital tract by means of fistula and is uniformly associated with ARMs.
Various classifications have been proposed for CPC, but classification proposed by Rao et al. In cases with complete pouch colon types I and IIas adequate length of the normal colon is absent, construction of distal colon by tabularizing coloplasty of the remaining colon has been proposed.
Single staged management of pouch colon has also shown good results, though few authors have found increased mortality with this approach. Intravertebral fixation of the filum terminale results in the tethering of the spinal cord In recent years, high resolution diagnostic equipment such as spinal MRI and three-dimensional CT have demonstrated a higher frequency of tethered cord in the setting of ARM than previously estimated.
A conservative approach has been advocated for ARM patients with asymptomatic tethered cord. Prophylactic surgery appears to have a minimal benefits and release of tethered cord should be done in symptomatic cases only.
Secondary reconstructions to improve fecal continence have been used extensively in patients with ARMs. In most reports, the long-term functional outcome is not better in patients who had secondary surgery and may be worse than in those with only primary repair. Rerouting of the pulled-through bowel has been advocated for patients who have a misplaced anal canal following primary operation. The bowel may traverse the levator and not lay anterior to it. Most patients who undergo repair of an ARM suffer from variable degrees of fecal incontinence, depending upon the type of anomaly, associated anomalies and the effectiveness of corrective procedure.
The functional results after surgical correction of ARMs are often assessed by a manometric study, neural electrophysiological studies, magnetic spinal stimulation, and fecoflowmetry.