Perineal reconstruction is most commonly performed after tumor extirpation. Common cancers affecting the perineum include colorectal, vulvar, vaginal, uterine, and bladder subtypes. The unique anatomy of the perineum often requires many considerations for maintaining function, cosmesis, obliteration of dead space, and achieving a healed wound. Often reconstruction following tumor extirpation is further complicated by prior radiotherapy for the same cancer. This makes reconstruction more challenging and highlights the importance of importing healthy vascularized tissue into the area. Radiotherapy alone can, of course, be a requirement for needing perineal reconstruction but this is less likely. Trauma is an occasional cause for a need to undertake perineal reconstruction and serious burns are one of the more likely examples. Infection is a cause for patients to require perineal reconstruction, particularly in cases such as necrotizing fasciitis and Fournierβs gangrene, once debridement has been undertaken and the infection is controlled. A need for reconstruction for an isolated vascular event would be rare other than in the context of a necrotizing infection.1,2
2. Mericli AF, Martin JP, Campbell CA. An algorithmic anatomical subunit approach to pelvic wound reconstruction. Plast Reconstr Surg 2016;137(3):1004β1017 The perineal area can be divided into two triangular zones, the anterior urogenital triangle and the posterior anal triangle (Fig. 64.1). The perineum represents the area between the scrotum or vagina and the anus. The anatomic boundaries are as follows: β’ Anterior: Pubic arch and the arcuate ligament of the pubis β’ Posteriorly: Tip of the coccyx β’ Lateral and medial: Inferior rami of the pubis and the ischial tuberosity β’ Superior: Pelvic floor β’ Inferiorly: Skin and fascia In the female the external genitalia comprise of the mons pubis, labia majora, labia minora, clitoris, and vestibule. The vagina is a tubular structure that extends from the vaginal opening to the uterus. In the male, the external genitalia comprises the penis, which has a root (radix), a body (corpus), and epithelium (glans penis). In addition, there is the scrotum which is a sack of skin and smooth muscle that houses the external spermatic fascia, Fig. 64.1 Perianal triangle. Anterior urogenital triangle Posterior anal triangle testes, epididymis, and ductus deferens. Knowledge of the anatomy of the perineum is key to understanding the principles of reconstruction and the flaps available for doing so.1β3
3. Moore KL, Dalley AF, Agur AMR, eds. Clinically Oriented Anatomy. 7th ed. Philadelphia: Wolters Kluwer/Lippincott Williams & Wilkins; 2013 Skin grafts certainly have a role in perineal defects, both in split- and full-thickness forms. One of the main challenges is ensuring they remain secure on the recipient bed without movement due to friction or shear in the early days post surgery. This affects the perineum because of a number of factors including the anatomic contour as well as external compression forces that act upon them. One option that is sometimes employed to help grafts remain secure is to use a negative pressure dressing. This approach can be taken in the perineum, but the same limitation applies in that the contours, movement, local hair growth, and moisture make this a relative challenge. Recipient vascularity is suboptimal after radiation, but not uniformly so in perineal reconstruction cases. The aesthetic outcome is generally adequate and patient positioning is unaffected as this will normally be the same irrespective of whether flaps or grafts are used.1β3
The rectus abdominis flap is considered to be the workhorse flap for perineal reconstruction. It is used for large perineal defects and, in particular, following abdominoperineal resection. It also is useful for vaginal reconstruction. One of the key benefits of using this flap is that it obliterates pelvic dead space with the muscle component and also provides skin cover where necessary in the form of a vertical rectus myocutaneous (VRAM) flap or transverse rectus abdominis myocutaneous (TRAM) flap. Traditionally, when anteroposterior (AP) resection was performed as an open procedure, the harvest of this muscle was particularly favorable. With moves toward laparoscopic AP resection, other flaps such as a gluteal advancement have gained popularity and provide a fair alternative.1,2
There are a number of locoregional flaps commonly used for perineal reconstruction. These include the gracilis, the rectus abdominis, the posterior thigh, the Singapore, and anterolateral thigh flaps. The blood supplies to these flaps are as follows: β’ Rectus flap = Deep inferior epigastric artery β’ Posterior thigh flap = Profunda femoris artery perforators β’ Singapore flap = Pudendal arteries (giving rise to labial arteries) β’ Gracilis flap = Medial circumflex femoral artery β’ Anterolateral thigh flap = Lateral circumflex femoral artery (most commonly the descending branch)1β5
The Singapore flap is a neurovascular island flap that is very useful for reconstructing vaginal wall defects where there is no significant dead space to fill (i.e., more superficial defects requiring relining and no dead space to fill). This flap receives its arterial supply from the labial arteries which, in turn, derive their supply from the pudendal arteries. Advantages of using this flap are that it is reliable, uses thin pliable tissue from adjacent to the defect (medial thigh/groin crease), has good reach to the vaginal area, and is sensate, and the donor can be closed directly leading to high levels of cosmesis and function. A limitation may be the inability to fill a large dead space, and in this scenario, a bulkier flap containing muscle would be indicated such as a rectus or gracilis. Where the defect dictates a larger thin pliable flap, bilateral Singapore flaps can be reliably used.1,2 The posterior thigh flap receives its blood supply from the inferior gluteal artery, or profunda femoris perforators. This flap can be useful for pressure sore management or in perineal reconstruction where other flaps are not available.3 The anterolateral thigh flap is a reliable flap to use for both regional reconstruction and as a free tissue transfer. It is supplied by the descending branch of the lateral circumflex femoral vessels but tends to be used as a second-line choice for perineal reconstruction. It is used as a pedicle flap for abdominal wall reconstruction and groin defects, for example, following complications of groin dissection. The gracilis flap is based on the medial circumflex femoral vessels. It could be used for this scenario but would be better reserved for defects which require dead space filling such as a rectovaginal fistula. Groin flaps are supplied by the superficial circumflex iliac vessels and can be used for many defects as free tissue transfers or some local defects. They tend not to be used for vaginal reconstruction.4
Phalloplasty techniques are sometimes required after trauma, gender reassignment surgery, or resectional surgery for penile carcinoma. The tubed free radial forearm free flap is considered to be the gold standard. When this flap is used, sensation is provided by coapting the antebrachial cutaneous nerves in the flap to the pudendal nerve. Other options and considerations include the fibula flap. One advantage of this is that the bony construct eliminates the need for a secondary procedure to place a prosthesis. However, it does mean the phallus is permanently rigid. In addition to these free tissue options, pedicled rectus or lateral thigh flaps may be considered, although these flaps will add additional stages to the reconstruction.1β3
The Cordeiro classification is used for vaginal defects ad their reconstruction. It categorizes defects according to whether they are partial or circumferential into types I or II, respectively. These subtypes are then further split into either A or B groupings. Type IA defect involves the anterior or lateral wall, whereas type IB involves the posterior wall.1 Type IIA defects involve the upper two-thirds of the vagina whereas type IIB defects are total circumferential defects (Fig. 64.2): β’ Type I: Partial β’ Type IA: Partial defect of the anterior or lateral wall β’ Type IB: Partial defect of the posterior wall β’ Type 2: Circumferential β’ Type IIA: Circumferential defects of the upper two-thirds of the vagina β’ Type IIB: Circumferential total vaginal defects The classification does not therefore consider the measured size, the cause, nor the chronicity of the defect. Furthermore, it does not consider the labia, perineum, or anus. The classification includes an algorithm which guides reconstruction as follows: β’ Type IA defects: Singapore flaps or other perforator based fasciocutaneous flap β’ Types IB and IIA: Pedicled rectus abdominis, can be rolled or tubed β’ Type IIB: Bilateral pedicle gracilis or rectus abdominis flap β’ Free jejunum has also been used for circumferential vaginal defects Fig. 64.2 Vaginal defect classification. A B C D E