The July issue of Techniques in Coloproctology includes two papers about laser treatment of fistula-in-ano: an editorial by Giamundo (Laser treatment for anal fistulas: what are the pitfalls?) and an original article by de Bonnechose et al. (Laser ablation of fistula tract (LAFT) and complex fistula-in-ano: “the ideal indication” is becoming clearer…).
The main indication of the technique is the treatment of high or complex anal fistulas, where other surgical procedures may impair the continence.
Since in Literature there is a great variability in the results of this technique – in particular Giamundo reports a healing rate of 71,1% [Giamundo et al. Colorect Dis 2014], while de Bonnechose of 44,6% – the aim of the Authors is to investigate the predictive factors of success or failure of laser treatment for fistula-in-ano.
There may be several explanations for the different success rates of the studies previoulsy published in the Literature.
The patients are not exactly comparable between studies: the main biases are the great variability in type, length and size of the fistulas, the size of the internal orifice and the proportion of inter-sphincteric, trans-sphincteric or supra-sphincteric tract.
Moreover, the shrinkage of fistula tracts caused by laser energy is linked to the following features:
- fistula tract length
- fistula diameter (less effective over 4-5 mm)
- internal orifice size
that are difficult to estimate.
The Authors agree on the need of fistula tract preparation as a bridge-to-surgery with abscesses drainage, fistula curettage and placement of a loose seton, that may induce the formation of fibrotic tissue and fistula caliber.
Since LAFT is a blind procedure, another critical point is the evaluation of the amount of the necessary energy for the shrinkage, in terms of total amount of energy administered and of amount of energy delivered per centimeter of fistula. The last is difficult to be measured but Giamundo believes that is more significative than the total amount of energy administered during the procedure.
De Bonnechose identifies two fistulas categories based on the total amount of energy administered:
- fistulas requiring less than 400 J
- fistulas requiring more than 400 J
Fistulas requiring less than 400 J had a significantly higher healing rate (65%) compared to fistulas requiring more than 400 J (32%): this could be explained by larger diameter fistulas that require more energy to be closed or by the “overburning” effect of too much energy. De Bonnechose identifies a trend in favor of lower energy/cm, but without reaching statistical significance.
Another questionable point is the treatment of the internal orifice: in the study by Bonnechose the internal orifice was not closed, but in patients with wide internal orifice (larger than the probe) the heling rate was lower (15.4%). Since that both the Author suggest the closure of a wide internal orifice with an advancement flap.
Finally, when we consider as end point the recurrence rate, real recurrence must be differentiated from non-healing or persistent fistula.
In conclusion all the Authors confirmed that the fistula-in-ano laser treatment is an effective sphincter-saving technique and the success rate should be compared with the other complex anal fistulas sphincter sparing techniques (fibrin glue, plugs).
At the same time, this comparison is complex since the huge variability of the considered characteristics.
SOS Coloproctologia e disfunzioni del pavimento pelvico