Dermal Advancement Flap

Fig. 15.1

Dermal flap for treatment of anal fistula. (a) Flap is marked out, incorporating both the internal and external fistula openings. (b) Originating crypt is excised and flap is advanced. (c) Flap is sewn into place, leaving open area of subcutaneous fat to heal by secondary intention

Although some studies report a postoperative hospitalization of a few days [1–4], patients can usually be discharged the same day with narcotic pain medication and instructions for sitz baths. Postoperative antibiotics are not necessary. A bulking agent may be helpful to avoid postoperative constipation. Particularly for male patients, it is helpful to keep them in the recovery area until they have demonstrated the ability to void as urinary retention can occur.

Modifications of the dermal flap include the V-Y flap and the “house” flap (Fig. 15.2). As in the standard flap procedure, the internal opening is excised and the flap advanced into the anal canal. In both of these modifications, however, the open area in the perianal skin resulting from advancement of the flap is able to be closed due to the geometry of the flap.

Fig. 15.2

Variations of dermal flap. (a) Mobilized tissue for V-Y flap. (b) Completed V-Y flap. (c) Mobilized tissue for house flap. (d) Completed house flap

Results

Healing of Fistula

Dermal flap has a good success rate for healing anal fistulas, with most healing rates reported to be in the 70–80 % range (Table 15.1). In fact, the healing rate may be even greater than this, as many of the studies demonstrating lower success rates had small numbers of patients. In the three largest studies, each including at least 40 patients and together comprising 170 patients, the healing rate was at least 80 % in each study [5–7]. When the three studies are aggregated, the combined success rate is 88 %. Thus, the healing rate for dermal flap is quite high, particularly if it is performed by surgeons who use dermal flaps frequently to treat anal fistula.

Table 15.1

Results of dermal flap repair of anal fistulas

Authors	Number of patients	Fistula type	Primary success rate (%)	Ultimate success rate (%)	Comments
Alver et al. [1]^a	4	3 TS	75	100	RVF did not heal
Alver et al. [1]^a	4	1 RVF	75	100	RVF did not heal
Amin et al. [15]	18	10 TS	72	83
		4 IS
		4 SS
Athanasiadis et al. [2]^a	14	RVF	85	–	All patients had Crohn’s disease
Chew and Adams [14]	6	TS	100	–	Internal sphincter was incorporated into flap
Del Pino et al. [18]	11	TS	73	–	Recurrence in 2 of 3 patients with Crohn’s
Ellis and Clark [13]^a	22	“Complex”	75	–	Success rate is for dermal flap without fibrin glue
Ellis and Clark [12]^a	27	25 TS	78	–
Ellis and Clark [12]^a	27	2 RVF	78	–
Hesterberg et al. [11]	10	RVF	70	90	All patients had Crohn’s disease
Ho and Ho [3]^a	10	TS	100	–
Hossack et al. [9]	16	SS	94	–
Jun and Choi [5]	40	35 TS	98	–
Jun and Choi [5]	40	5 SS	98	–
Koehler et al. [17]^a	8	Dorsal horseshoe	75	–
Nelson et al. [6]	65	Mixed	80	–
Robertson et al. [8]	20	Not stated	70	–	Six patients had Crohn’s disease
Sentovich et al. [4]^a	1	“Perineal”	0	–
Sungurtekin et al. [7]	65	49 TS	91	–
		15 SS
		1 RVF
Zimmerman et al. [10]	26	TS	46	–

Primary success rate is the percentage healed after first attempt at repair with advancement flap; ultimate success rate is percentage healed after additional intervention for initial failures

TS transsphincteric, SS suprasphincteric, ES extrasphincteric, IS intersphincteric

^aStudy included other interventions (e.g., endorectal flap) or other pathology (e.g., anal stenosis) but reported results are only for patients who had dermal flap for fistula

Because of the amount of dissection required, the wounds from dermal flap repair may take several weeks to heal. Overall, it appears most operative sites will heal in approximately 6 weeks [3, 7–9]. However, average healing times of as little as 2–3 weeks [5], or as long as 3 months [10], have been reported. Patients should therefore be counseled that it may be several weeks before complete healing is achieved.

The observed recurrence rate may depend partially on the duration for which the patient is followed. Among ten women with anovaginal fistulas associated with Crohn’s disease and repaired with dermal flaps, Hesterberg et al. observed recurrences at 4, 8, and 13 months [11]. In the large case series by Nelson et al., the latest recurrence was at 20 months [6]. Thus, success rates may vary depending on the length of follow-up, as recurrences can occur even more than 1 year after operation.

Complications

Complications associated with dermal flap are generally minor. The most commonly reported complication is minor separation of the external portion of the flap. Reported rates of this complication range from 5 % [7] to 50 % [9], with other reports falling between these two extremes [1, 8]. However, if the dermal flap is performed in the manner described earlier in this chapter, leaving a portion of the wound in the perianal skin open, this complication is rare. It seems this complication is more likely to occur when the skin is completely closed, as with a V-Y or house flap, likely due to excessive tension on the wound.

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