The aforementioned results of this study show mucosal injection to be a safe and feasible treatment for rectal prolapse in children with corrected anorectal malformation.
Not only is its success rate (94%), higher than what has been described for alternative therapies such as sclerotherapy (77% [11]), mucosal resection (66-75%) [12, 13] or rectopexy (30-90% [2, 14, 15], depending on technique).
The absence of relevant complications, short operating time leading to shortened anaesthesia time as well as short hospital stay must be valued especially in a patient collective that, in most cases, at a young age already has a long history of surgery and hospitalisation. Patients only had to stay in hospital overnight due to billing technicalities of the German healthcare system while the procedure itself could certainly be conducted in an outpatient setting.
The minimally invasive procedure avoids damaging the already fragile and underdeveloped continence apparatus. The possibility to almost immediately return to the patients’ bowel management regimen without losing rhythm is of great value to the children’s quality of life.
The simplicity of the surgical technique and the wide availability of the necessary tools and supplies render it an easy option for standardised treatment.
While this technique has been referred to as and compared to sclerotherapy [7], the principle is a different one: Sclerotherapy describes an injection into the rectal corpus cavernosum, leading to a reduction in haemorrhoids on one hand, and a strengthened connection between mucosal and muscular layers of the rectal walls through fibrous adhesions on the other.
The technique described in our study aims for an injection in the mucosa only, bulking up the surrounding tissue und thus supporting the hypoplastic pelvic floor as counter bearing for the rectal mucosa, considering the different pathogenesis of rectal prolapse in children with anorectal malformations, and offering a more suitable treatment.
While publications on the treatment of rectal prolapse in this patient collective are scarce, some comparisons and conclusions can be drawn: While Belizon et al. [4] focus on epidemiology and predisposing factors instead of treatment options, Brisighelli et al. [13] stress the importance of sufficient bowel management as primary treatment for rectal prolapse and characterize operative treatment as merely symptomatic. In our case, all of our patients already conducted sufficient bowel management preoperatively without reduction of rectal prolapse. Furthermore, our method does not stop at treating symptoms but tries to improve the underlying anatomical conditions.
Sato et al. [12] suggest a two-flap anoplasty. In comparison, this technique comes with a significantly longer operating time (average 170 minutes), two weeks of total parenteral nutrition and hospital stay, and seems more invasive, with the threat of losing features of the highly specialized anal skin.
Zornoza et al. [16] present a long-term analysis of their management of rectal prolapse. This publication focuses on very early postoperative prolapse, treatment was conducted before colostomy closure. As only the abstract was available to us, no conclusive comparison could be made; albeit a higher recurrence rate (15%) was reported.
Of course, our study is not void of certain limitations:
Firstly, a larger patient sample would be desirable. Anorectal malformations per se are a rare occurrence (incidence 4:10,000 new-borns [17]), so collecting larger patient groups with this specific complication after treatment will always be an issue, seeing as our department already is one of the bigger centres for treating anorectal malformations in Germany.
Secondly, follow up time must be considered specifically seeing as both absorbable and non-absorbable agents were injected and, while not showing any short-term differences, might show variable long-term outcomes. Longer-term effects of up to 18 years’ follow up are known for both agents when used for VUR treatments, with both showing favourable outcomes (albeit a slightly higher recurrence rate for Dx/HA) and hardly any observed long-term complications [18–20].
While non-absorbable PPC agents seem to be holding most their volume over time, possibly due to increased fibrosis[10], a slight volume loss was described for Dx/HA agents, which might show recurrences on the long term[8, 21].
One must still consider possibly different results and impacts on the rectal mucosa. Animal studies with injection into different tissues did not seem to induce DNA- or major tissue changes [8, 9]. Also, Dx/HA agents have been successfully used for a multitude of purposes [22–24] including rectal prolapse in children without anorectal malformations [7] over ten years, without any long-term issues.