Rectus Abdominis Myocutaneous Flap

This technique was described by Taylor et al. in 1983 [35]. It is an excellent method for closing a large perineal defect. Based on the inferior epigastric artery and vein, it may be passed into the pelvis to close the pelvic floor and fill the dead space. It is best employed pro-phylactically in high risk patients at the time of proc-tectomy when potential perineal wound problems are anticipated [17], or at the time of abdominoperineal excision for a large neoplasm [34] when extensive perineal excision is needed in Crohn's disease [36], or, finally, when the combined approach is used to excise a large perineal sinus in Crohn's disease or after radiotherapy [16]. As a delayed or secondary procedure, the advantages of this flap must be weighed against the potential difficulties and morbidity of having to reenter the lower abdomen and mobilise the bowel to provide space to pass this flap into the pelvis, which is often severely fibrotic. Moreover, in very large pelvic wounds, the bulk of a single rectus abdominis muscle is inadequate to entirely obliterate the dead space [17]. In cases in which a completion proctectomy is performed solely by a perineal approach or for closure of a chronic perineal sinus gluteus maximus, posterior thigh or even gracilis, flaps are often adequate and do not require laparotomy [19].

A rectus abdominis myocutaneous flap has to be designed opposite to the site of the stoma provided that the muscle on that side has not been damaged by repeated laparotomies or by a previous stoma. It is important to assess the vascular supply of the flap preoperatively and, if necessary, an angiogram can be performed, particularly if the patient has received groin irradiation [34]. The abdomen is opened and a synchronous combined excision of the rectum and the perineal sinus is completed. A disc of skin slightly larger than the perineal defect is cut over one rec-tus muscle, 3-4 cm below the costal margin, to reconstruct the perineum and occasionally the posterior aspect of the vagina.

Gracilis Myocutaneous Flaps

Fig. 4. Vertically oriented rectus abdominis myocutaneous (VRAM) flap. The skin paddle is designed to match the size of the defect (top left). The myocutaneous flap is raised and includes the anterior fascia of the rectus sheath (top right). Marking the line of perineal resection including posterior vaginal wall (bottom left). The skin paddle is secured with interrupted sutures (bottom right)

Fig. 4. Vertically oriented rectus abdominis myocutaneous (VRAM) flap. The skin paddle is designed to match the size of the defect (top left). The myocutaneous flap is raised and includes the anterior fascia of the rectus sheath (top right). Marking the line of perineal resection including posterior vaginal wall (bottom left). The skin paddle is secured with interrupted sutures (bottom right)

Traditionally, the two main types of flap are described by the orientation of the skin paddle, i.e. the vertical rectus abdominis flap (VRAM] or the transverse rectus abdominis flap (TRAM) [37]. The subcutaneous tissue is divided with the skin to the rectus. The segment of rectus above the flap is divided, ligat-ing the superior epigastric vessels. The inferior epigastric vessels are then dissected free, dividing branches or tributaries which do not supply the inferior aspect of the rectus muscle. An adequate length of vascular pedicle is needed to rotate the skin disc and underlying muscle through the pelvis and on to the perineum. The defect in the rectus sheath is closed over suction drainage and the skin flap is sutured to the perineal skin over suction drainage with the muscle filling the dead space above (Fig. 4) [16]. Undoubtedly this technique may compromise the strength of the abdominal incision and may compromise management of stoma complications or recurrent ileal disease, particularly if the stoma needs to be resited [12].

Smith et al. [38] published the results of 22 patients undergoing the Taylor flap, 21 at the time of primary operation, but these were predominantly for vaginal reconstruction alone. Bell et al. [34] reported a series of 31 consecutive patients undergoing one-stage rectus abdominis myocutaneous flap reconstruction of extensive perineal wounds expected to generate substantial morbidity: 26 had surgery for recurrent or persistent epidermoid anal cancer or low rectal cancer and 21 had high-dose preoperative radiotherapy.

The authors modified the original Taylor's technique using an oblique skin paddle over the longitudinal rectus muscle, mainly because the oblique flap showed many advantages compared to the vertical one. In fact, the laxity of the abdominal skin is more significant in the oblique direction than in the vertical direction, allowing a larger paddle and minimising tension at the donor site [34]. Three weeks after operation, complete healing of the perineal wound was seen in 27 of the 31 patients and none developed a chronic sinus. At the completion of follow-up (median 9 months) there were no unhealed wounds.

Collie et al. [36] reviewed a series of 15 patients who received proctectomy for Crohn's disease, five of which had a gracilis interposition and 11 a rectus abdominis flap (one that had failed after gracilis interposition). All 11 patients with a rectus abdomin-is flap had a healed perineum at 3 months after surgery and no donor-site complications. The perineum healed in only one of those who had gracilis interposition.

Loessin et al. [39] employed an inferiorly based transpelvic rectus abdominis muscle or musculocu-taneous flap to treat persistent sacral and perineal defects secondary to radiation and abdominoper-ineal resection with or without sacrectomy-14 of the 15 patients achieved healing and 7 had no complications. The remaining eight patients required one or more operative debridement or prolonged wound care to accomplish healing of the wound. Many authors think that reconstruction with a VRAM flap represents the best chance for facilitating healing in irradiated pelvises and they recommend its use for locally advanced rectal cancers requiring intense preoperative and intraoperative chemoradiation [40, 41]. In Table 1, the results of VRAM flap repair used for primary perineal repair soon after APR and for repair after PPS wide excision are reported.

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Responses

  • gorbaduc
    Can having a colostomy increase your chances of rectus abdominis?
    5 years ago
  • declan
    What is a rectus muscle myocutaneous flap?
    1 month ago

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