Anal canal duplication (ACD) is the least frequent digestive duplication. Symptoms are often absent but tend to increase with age. Recognition is, however, important as almost half of the patients with ACD have concomitant malformations. We present the clinical history of an eleven-year-old girl with ACD followed by a review of symptoms, diagnosis, treatment, and prognosis based on all the reported cases in English literature.
An eleven-year-old foster child was referred to the paediatric gastroenterology department because of an extra perianal orifice. The patient complained of anal pruritus. Previous treatment with mebendazole because of the suspicion of oxyuriasis had no effect. Physical examination revealed an extra orifice, in the midline posterior to the anus. Rectal palpation was normal. The anal canal appeared normal, with normal anal reflexes. This extra orifice had been observed at birth, with an expectative management advised in her native country. Cardiac ultrasound was normal. Magnetic resonance imaging (MRI) revealed a normal sacrum and coccyx but could not demonstrate the extra orifice or fistula. The genitourinary system, as evaluated in MRI, was normal. Fistulography (Figure
Fistulography revealing a blind ending tubular structure.
The patient and her parents were counselled about the diagnosis of ACD and the possible complications: inflammation and malignancy. Nevertheless they refused surgical mucosal stripping.
ACD is the least frequent digestive duplication. Clinically, it presents itself as an extra perineal orifice located just behind the anus. Clinically, it is difficult to differentiate ACD from a rectal or anal fistula, however, in noncomplicated ACD inflammation will be absent. Only histology gives diagnostic certainty describing 3 characteristics of ACD: squamous epithelium in the caudal end, transitional epithelium in the cranial end and smooth-muscle cells in the wall of the canal [
Summary of all reported anal canal duplication cases in English literature.
Reference | No. | Sex | Localization | Type | Symptoms | Age | Associated anomalies |
---|---|---|---|---|---|---|---|
Our patient | 1 | 1 F | Post | 1 tub | 1 mild | 11 y | None |
Sinnya (2012) [ |
1 | 1 F | Post | 1 tub | 1 complication | 15 y | Dysplastic coccyx |
Lippert (2012) [ |
1 | 1 F | Post | 1 cyst | 1 complication | 12 y | None |
Narci (2010) [ |
2 | 2 F | Post | 2 tub | 2 asympt | 5 y |
None |
Koga (2010) [ |
10 | 10 F | Post | 10 tub | 3 asympt |
6 m |
1 hypoplastic kidney |
Carpentier (2009) [ |
2 | 1 F |
Post | 1 tub |
1 mild |
2.5 m |
1 spina bifida occulta, thetered cord, hydronefrosis |
Kratz (2008) [ |
1 | 1 F | Post | 1 cyst | 1 complication | 16 y | None |
Lisi (2006) [ |
12 | 11 F |
Post | 10 tub |
6 asympt |
17.8 m |
1 anorectal malformation |
Tiryaki (2006) [ |
2 | 2 F | Post | 2 tub | 1 asympt |
7 y |
1 none |
Choi (2003) [ |
6 | 6 F | Post | 6 tub | 6 asympt | 4.5 m |
6 none |
Ochiai (2002) [ |
1 | 1 F | Post | 1 combined | 1 mild | 6 y | None |
Jacquier (2001) [ |
6 | 6 F | Post | 6 tub | 5 asympt |
2.5 m |
1 sacral teratoma, lumbosacral meningomyelocoele |
Ponson (2001) [ |
3 | 3 F | Post | 3 tub | 1 asympt |
23 m |
3 none |
Hamada (1996) [ |
2 | 2 F | Post | 2 tub | 1 asympt |
3.5 y |
1 cleft lip |
Tagart (1977) [ |
4 | 1 F |
3 right side |
3 tub |
4 complication | 29 y |
None |
Aaronson (1970) [ |
1 | 1 F | Post | 1 tub | 1 asympt | 3 m | 1 anterior sacral meningocoele, covered anus |
| |||||||
Total group numbers | 55 | 49 F |
52 post |
48 tub |
26 asympt |
4.6 y |
20 associated anomalies |
Total group percentage % | 89% F |
94.5% post |
87% tub |
47% asympt |
36% associated anomalies |
Overview of the reported cases in English literature (first author and year of publication between brackets) with the number (No.) of reported cases, the localization (post: posterior), type of lesion (tub: tubular, cyst: cystic, both combined), presenting symptoms (asympt: asymptomatic; mild: mild symptoms (pruritus, discharge, constipation, diarrhea, and limited pain); complications (inflammation, abscedation)), age mean age and range between brackets in days (d), months (m), or years (y), and number and type of associated anomalies.
Two hypotheses concerning the origin of anal canal duplication are suggested in literature.
Choi and Park postulate it as a consequence of recanalization of a cloacal membrane excess in late embryonic life [
Half of the patients with ACD are asymptomatic. Parents or caregivers notice a perianal orifice posterior to the anus. Mild symptoms such as anal pain, pruritus, mucous discharge and constipation are present in one third of the patients. Perineal abscess or inflammation can, however, be the presenting complication of ACD. Although ACD is present at birth, it can easily be overlooked resulting in a widely varying age at presentation (Table
Clinical suspicion and characteristics can lead to a tentative diagnosis of ACD. Imaging studies give extra information on the extent of the lesion and concomitant anomalies. MRI of the pelvis and presacral area gives a detailed view of the region. In neonates, however, ultrasound examination is preferred as they require general anaesthesia for MRI. Associated malformations are described in 35% (Table
It is advised to treat even asymptomatic ACD with surgery to prevent malignancy and infectious complications and to get diagnostic certainty with the histological examination of the excised material. Different approaches are suggested in literature. The majority of patients received an ACD removal via perianal or posterior sagittal approach. Mucosal stripping of the ACD is a new, less invasive approach most frequently used when the ACD is located very close to the anal canal. Surgical repair is associated with good prognosis and minor surgical sequelae. Up to now only one patient suffers from sphincter insufficiency [
Anal canal duplication is an extremely rare congenital anomaly of the digestive tract. A posterior perianal orifice, particularly in female patients, sometimes accompanied by aspecific symptoms should raise the suspicion of anal canal duplication. Clinical suspicion can be elaborated by imaging studies visualising the ACD and associated anomalies. Surgical removal, before the age of 1, is advocated to prevent complications. Histology gives confirmation of this anomaly.
S. Van Biervliet and E. Maris shared in this paper.