Anorectal malformations (ARM) are a complex congenital anomaly accompanied by additional anomalies resulting from the abnormal development of part or all of the urorectal septum. In these patients, besides the anorectal canal disorders, additional anomalies of many systems may accompany. Anorectal malformation comes to mind
- Narrow breech hole
- Anus located anteriorly
- Congenital breech hole closed by a membrane
- The last part of the large intestine is closed and cannot be combined with the anus.
- It occurs when the last part of the large intestine is mouthed to a part of the urinary tract or reproductive system, that is, fistulized.
Frequency
Although the frequency of anorectal malformation differs from country to country, it is generally 1 in 4500-5000 live births. Its incidence is 1.4-1.6/1 higher in boys than girls. Although maternal age, number of births, race and genetic relationship are suspected, these relationships have not been fully revealed. However, anorectal malformation can be seen in three generations of the same family, and the presence of anorectal malformation in the first children significantly increases the risk of anorectal malformation in the next children, this rate is approximately 1%.
Etiology
Although the etiology is not completely clear in patients with anorectal malformation, it has been determined that genetic predisposition, multisystem syndromes (VACTERL, Townes-Broks, Currarino's and Pallisten-Hall), as well as adriamycin, etretinate and vitamin A deficiency cause ARM as a result of experimental studies.
Pathogenesis
Anorectal malformations occur when there is an inability to separate the genitourinary system from each other in the rectum or to perforate the perineum even if they are separated. According to a more recent theory, although the urorectal septum moves distally and comes very close to the cloacal membrane, it never makes contact.
Additional Anomalies
The more proximal the distal end of the blunt-ended intestine is, the higher the incidence and severity of additional anomaly. In anorectal malformations, especially sacral vertebral deformities and urinary system anomalies are seen quite frequently and are determinants of poor prognosis. The most common anomaly group is genitourinary system anomalies. The frequency of genitourinary anomalies in ARMs is between 28-89%. The most common genitourinary system anomaly is vesicoureteral reflux. With the introduction of imaging techniques (US and MRI), spinal dysraphism was observed in 17% of low-type ARMs, 34% of high-types, and 46% of cloacal malformations. Anorectal malformations are accompanied by gastrointestinal system anomalies at a high rate. Esophageal atresia is seen in 10% of anorectal malformations. VATER syndrome associated with anorectal malformations was described by Quan and Smith and expanded to VACTERL (vertebral, anorectal, cardiac, tracheoesophageal and limbs).
Classification
In the Wingspread classification made according to the relationship of the blind end of the rectum with the levator muscles, anorectal malformations are divided into 3 basic groups: high type (supralevator), low type (infralevator) and intermediate type (intermediate) that does not fit high or low type.
