Combined serratus anterior and latissimus dorsi myocutaneous flap for obliteration of an irradiated pelvic exenteration defect and simultaneous site for colostomy revision

Reconstruction of a wall defect after abdominoperineal resection is very demanding with regard to its functional outcome. Several surgical methods are used, with re-suturing, free skin grafting and local flaps, which can be useful when the defect is relatively small [1]. However, for larger defects with further complications, such as the formation of a colostomy or iliac conduit, and wound infection, a large free flapis usually required to repair the abdominal wound [2–4].

We present the case of a colon fistulae and pelvic exenteration abdominal wall defect, treated with a free combined serratus anterior and latissimus dorsi myocutaneous flap, along with a new colostomy fashioned in a free flap, resulting in a successful outcome.

Simple wall defects after abdominoperineal resection due to skin marginal necrosis and seroma development have sometimes been reported, and these small defects can be closed with simple methods, including debridement and direct re-suture, the component separation method, and with pedicled muscle or fasciocutaneous flaps [1, 5].

A pedicled tensor fascia lata fasciocutaneous flap has usually been used for abdominal defects [6]. However, large full-thickness abdominal wall losses caused by gunshot wounds, severe infection such as necrotizing fasciitis and intra-abdominal sepsis, or en bloc excision of neoplasms, require free flap transfer for reconstruction, because the distal third of the tensor fascia lataflap is at risk of necrosis unless a delaying procedure is included [2–4]. A pedicled anterolateral thighflap may serve as a good portion for the reconstruction of a lower abdominal wall defect, and it is also available for whole abdominal wall defect restoration if it is applied as a free flap. The advantages of this flap are that it can be harvested as a musculocutaneous flap with the vastus lateralis muscle to fill a tissue defect, and the lack of a need for changing position facilitates harvesting of the flap [7, 8]. However, the vastus lateralis muscle is too small to fill the large pelvic cavity, and harvesting a large amount of the vastus lateralis carries a high risk of morbidity at the donor site [9].

Reconstruction of the major defect in the abdominal wall in our case led to several problems, including: a non-healing wound with infection due to irradiation, a large dead space due to pelvic exenteration, and continuous contamination of the pelvic cavity due to stools from the ruptured bowel. First, a free flap transferwas required to treat these large irradiated wounds, because the tissue surrounding the ulcer crater has often been compromised by radiotherapy. Thus, if the reconstruction were performed with a local flap, it would have resulted in the loss of at least part of the flap [10]. Furthermore, a free flap is supplied by large blood vessels, which may promote the healing process in irradiated tissue [11]. When performing a free flap transfer around an irradiated area, identifying an acceptable recipient vessel is not always easy. Chronic endothelio-angiitis in recipient vessels caused by radiation may be one of the factors leading to thrombosis [12]. So, it is important to select a flap with a long pedicle, as the suitable recipient vessel may be distant from the wound. In our case, the inferior epigastric vessels, the first choice for a recipient vessel, collapsed and did not supply sufficient blood flow due to the radiation damage. Thus, there was further vessel dissection until our realization that the profunda femoris artery provided a sufficient amount of blood.

Second, restoration of abdominal muscle defects requires synthetic materials or a flap to prevent a hernia. The insertion of synthetic materials has been reserved for large defects of the abdominal wall, but they have proven increased complication rates, especially in contaminated wounds [2, 6]. Therefore, a myocutaneous free flap is desirable. The close continuity of the remaining rectus abdominis muscle after debridement and the muscle in the transferred flap will prevent the formation of hernias [3]. Third, our case required a durable skin component to make a new stoma, and a large area of soft tissue to occupy the large pelvic dead space.

To resolve these problems simultaneously, a combined serratus anterior and latissimus dorsi myocutaneous free flap was applied to cover the raw surface, to reinforce the abdominal wall and to fashion a new colostomy, as well as filling the pelvic cavity with a large muscle body with a long vascular pedicle. This is the optimal method for reconstructing severe abdominal wall defects associated with many complications.

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.