Resultados clínicos y funcionales tras el tratamiento de las fístulas perianales complejas con colgajo transanal de avance. Impacto de diferentes modificaciones técnicas.

Thesis entitled "Clinical and functional results after treatment of complex fistula-in-ano with transanal advancement flap. Impact of different technical changes ". Transanal advancement flap is the most accepted approach for treating complex fistula-in-ano. However, the thechnical procedure of the flap varies within institutions and surgeons, so the evaluation of the results may be contradictory. Although there is no consensus about how the shape and thickness of the flap should be, the full-thickness that includes the entire internal sphincter muscle seems to have the best results regarding recurrence, despite this fact, studies on pressive changes in patients undergoing this technique are limited. Related to the treatment of the fistula tract, the fistulectomy "core out" is a widely used approach. Sometimes, it can be a long, tedious and difficult process, which could damage the external sphincter muscle and cause manometric changes affecting continence. The simple curettage of the tract is a much simpler method, nevertheless it may increase the risk of recurrence because of insufficient drainage. The comparison of these two procedures is not reported in the literature. The objectives of the study are: 1. To evaluate the changes in basal pressure along the anal canal, especially in the distal third of it, after performing full-thickness transanal advancement flap. 2. To analyze and compare anorectal manometry results after "core out" fistulectomy with curettage of the tract, in the cryptoglandular complex fistula-in-ano treated with transanal flap. 3. To analyze and compare clinical outcomes after performing fistulectomy "core out" with curettage, in relation to recurrence and faecal continence alterations. 4. To propose management guidelines for treating complex fistula-in-ano with transanal flap. 5. To assess risk factors for recurrence and incontinence. METHODS: This is a retrospective analysis from prospective database. One hundred nineteen consecutive patients with cryptoglandular fistula and normal preoperative continence, underwent full-thickness transanal advancement flap. 78 patients were treated with "core out" fistulectomy (group I) and 41 with curettage (group II). Functional assessment of patients was evaluated pre and postoperatively by Jorge-Wexner Continence Grading Scale and anorectal manometry. The following parameters were analyzed: maximum anal resting pressure (MRP), wich is usually located in the middle third of anal verge and shows the changes cost by the flap performance; inferior resting pressure (IRP), mesure at 0.5 cm from the anal verge, that evidences modifications in the lower third, where internal sphincter integrity remains; and maximum anal squeeze pressure (MSP) that reflects the external sphincter function. All patients had a minimum postoperative follow-up of 12-month. Recurrence was defined as the presence of an abscess arising in the aerea or evidence of fistulization. RESULTS: Results of the resting pressure along the anal canal: Manometric results showed a significant decrease in MRP after surgery of 49.9%, from 90.6±31.9 to 45.2±20 mmHg (p<0.001). IRP values did not differ significantly between pre and postoperative values (28.2±18.3 to 23.2±13.5 mmHg, p=0.1, NS). Manometric results "core out" vs curettage: In group I (n=55), MRP decreased significantly from 87.3±27.4 to 47±20.1 mmHg (p<0.001) and in group II (n=38) decreased from 92.8±34.2 to 44.3±20.6 mmHg (p<0.001). On the other hand, MSP dropped significantly after surgery in group I, from 240.3±99 to 189.9±78.9 mmHg (p<0.001), but no significant differences were demonstrated in the group II (217.3±74.8 to 203.8±77.6 mmHg, p=0.1). Results concerning faecal continence: at postoperative assesment, a Wexner score of 0 was identified in 76.5% of all score patients, 59 patients (75.6%) of group I and 32 (78%) of group II (p=0.3). The proportion of patients with a postoperative minor increase of the Wexner score was 19.2% (15 patients) in group I and 21.9% (9 patients) in group II, while 4 (5.1%) patients of group I and none of group II had a major increased of the Wexner score postoperative. We did not find statistically significant differences between groups. Relation of manometric findings in MSP to anal continence: in particular, in the four patients with a major increase of the Wexner score (Wexner≥4) the preoperative MSP was significantly lower than the other patients in group I (139±29.3 vs 248.2±98.3, p=0.02). Results about recurrence of fistula: We found recurrence in seven patients (5.9%): five patients (6.4%) in group I and two patients (4.8%) in group II without statistical differences significant between groups (p = 0.7). CONCLUSIONS: 1. Conducting a full-thickness transanal flap causes a decrease of the MRP in the middle third of the anal canal, due to the inclusion of the internal sphincter at the flap. It seems crucial to be careful to preserve the distal internal sphincter intact, it allows to keep the resting pressure in the distal or lower third, in order to avoid a "keyhole" deformity of the anal margin that can lead to mucus or stool leakage. 2. Fistulectomy "core out" causes a significant decrease in MSP that reveals damage to the external sphincter. Curettage is a simple technique that does not cause variations in MSP, because it preserves the integrity of it. 3. We have not detected significant differences in the rates of incontinence between "core out" and curettage. However, the "core out" can cause incontinence in high risk patients, which can be defined by preoperative manometric studies. We have not determined significant differences in recurrence rates between the "core out" and curettage. 4. Curettage should be the technique of choice in the management of fistula tract because: it is simpler, preserves the external sphincter and does not increase the recurrence rate. 5. Being under 50 years old has been the only associated factor with an increased risk of recurrence in univariate analysis. Concerning incontinence, previous fistula surgery has been the only factor involved. None of them has remained as an independent factor in the multivariate analysis.