Anorectal anomaly

Anorectal anomalies occur in approximately 1 per 5000 live births and are more common in males. 

An anorectal anomaly is usually identified clinically. There may be an anal dimple present on the perineum or there may be an apparently patent external orifice but with a digitally palpable membrane on examination. Meconium may be passed per urethra in boys or per vagina in girls. 

Sato Y, Pringle KC, Bergman RA et al (1988) Congenital anorectal anomalies MR imaging. Radiology 168 157-162... 

Anorectal anomalies are classified into three types of malformations high, intermediate, and low. Associated anomalies occur twice as often in the high and intermediate groups as in the low group. 

Ralph DJ, Woodhouse CRJ, Ransley PG (1992) The management of the neuropathic bladder in adolescents with imperforate anus. J Urol 148 366-368 Rivosecchi M, Lucchetti MC, Zaccara A et al (1995) Spinal dysraphism detected by magnetic resonance imaging in patients with anorectal anomalies incidence and clinical significance. J Pediatr Surg 30 488-490 Stephens FD, Smith ED (1971) Ano-rectal malformations in children. Year Book, Chicago... 

Stephens FD, Smith ED (1986) Classification, identification, and assessment of surgical treatment of anorectal anomalies. Paediatr Surg Int 1 200-205 Tunell WP, Austin JC, Barnes PD et al (1987) Neuroradio-logical evaluation of sacral abnormalities in imperforate anus complex. J Pediatr Surg 22 58-61 Wiener ES, Kiesewetter WB (1973) Urologic abnormalities associated with imperforate anus. J Pediatr Surg 8 151-157... 

Wilcox DT, Warne StA (2006) Urological problems in children with anorectal malformations. In Holschneider AM, Hutson JM (ed) Anorectal Malformations in Children. Springer, Heidelberg, 269-279 Yeung CK, Kiely EM (1991) Low anorectal anomalies a critical appraisal. Paediatr Surg Int 6 333-335... 

The embryological development of the anorectal segment is complex and as a result many anomalies are possible. Many classification schemes have been proposed, and whilst one of the simplest and earliest outlines (Cans 1970) is still in use it has been superseded by the Wingspread classification (see below). This is itself now likely to be superseded by a new classifcation (Krickenberg 2005), but publication of this is still awaited. 

Anorectal malformations are frequently associated with other congenital anomalies, especially of... 

Table6.1. Suggested guidelines (Nievelstein et al. 1998b) for MR protocol for neonates and infants with anorectal malformations (based on a 1-T or 1.5-T magnet using ahead coil for neonates and a phased arraybody coil for older children). Axial and coronal planes should be angled to be parallel and perpendicular to the pelvic floor. Imaging of the spinal cord and kidneys is only necessary if associated anomalies are suspected...

Carty HML (2002) Paediatric emergencies non-traumatic abdominal emergencies. Eur Radiol 12 2835-2848 Clatworthy H, Howard W, Lloyd J (1956) The meconium plug syndrome. Surgery 39 132-141 Currarino G, Coin D, Votteler T (1980) Triad of anorectal, sacral and presacral anomalies. AJR Am J Roentgenol 137 395-398... 

Nievelstein RA, van der Werff JF, Verbeek FJ et al (1998a) Normal and abnormal embryonic development of the anorectum in human embryos. Teratology 57 70-78 Nievelstein RAJ, Vos A, Valk J (1998b) MR imaging of anorectal malformations and associated anomalies. Eur Radiol 8 573-581... 

The term imperforate anus includes all kinds of anorectal malformations from covering of the anus by a thin skin membrane to high anorectal atresia - with or without a fistula, into the urethra or bladder - and to cloacal anomalies in females. It is well known that a high proportion of patients with imperforate anus have this maldevelopment in association with anomalies of one or several other... 

Very frequently more than one organ system is involved. This is also reflected by the so-called VATER or VACTERL association that combines vertebral anomalies, anorectal atresia, cardiac failure, tracheoesophageal fistula, esophageal atresia, renal dysplasia, and limb malformation. 

Stephens and Smith (1971) and others have demonstrated that the incidence of additional anomalies is twice as high in the high and intermediate group of anorectal malformations (85%) as in the low group (46%). These findings have been confirmed by the analysis of our 75 patients with anorectal malformations, which has shown an incidence of 85% in the high and intermediate forms versus 61% in the low forms (Hollwarth and Menardi 1983) (Table 8.2). 

Structural as well as functional anomalies are reported commonly in babies with anorectal malformations. Therefore, a careful evaluation of the urogenital tract is essential in these cases. 

The entire spectrum of imaging investigations and functional studies is necessary to detect urogenital anomalies in anorectal malformations. 

Boemers TML, de Jong TPVM, van Gool JD, Bax KMA (1996a) Urologic problems in anorectal malformations. 1. Uro-dynamic findings and significance of sacral anomalies. J Pediatr Surg 31 407-410... 

Parrott TS (1985) Urologic implications of anorectal malformations. Urol Clin N Am 12 13-21 Pellerin D, Berlin P (1967) Genito-urinary malformations and vertebral anomalies in ano-rectal malformations. Z Kinderchir 4 375-383... 

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