Perineal reconstruction with pedicled rectus abdominis myocutaneous flap after posterior pelvic exenteration -A 3D model study

Abstract

Introduction: Limited literature exists regarding the positional relationship between the pedicled-rectus abdominis myocutaneous (p-RAMC) flap and residual pelvic organs post posterior pelvic exenteration (PPE).

Presentation of case: Four patients underwent PPE and reconstruction with a p-RAMC flap. After harvesting the p-RAMC flap with the deep inferior epigastric artery and veins as the vascular pedicle, the intra-pelvic shortest pathway of the flap was created. We dissected the subcutaneous tissues of the flap donor site toward the perineal defect along the inner wall of the pelvis. The pubic origin of the rectus abdominis muscle was preserved. A three-dimensional model was constructed using an image processing software. The vascular pedicle ran almost linearly along the inner wall of the pelvis. The muscle belly was placed on the pelvic floor through the posterior wall of the urinary bladder which filled the dead space of the resected area. All flaps survived without significant complications.

Discussion: Assigning the cranial side of the flap to the perineum and caudal side to the pelvic floor could reduce postoperative intrapelvic complications. By preserving the pubic origin of the rectus abdominis muscle, a shock absorber of the pedicle of the flap was created, preventing over-traction of the flap while passing through the intrapelvic pathway.

Conclusion: A p-RAMC flap via intra-pelvic shortest pathway is an ideal reconstructive method for large skin defect in perineal area after PPE.

Keywords: Case-Series; Computed tomography; Pedicled-Rectus abdominis myocutaneous flap; Perineal reconstruction; Three-Dimensional model.

Fig. 1

Operative findings (Case 1). a) Preoperative examination suggest that the malignant tumour invaded beyond the dentate line. b) A 22 × 6 cm pedicled-vertical rectus abdominis myocutaneous flap is harvested. c) The flap is pulled from the donor site (arrow) to the perineal skin defect (arrowhead) along the intra-pelvic shortest pathway.

Fig. 2

Three-dimensional model of the reconstructed pelvic floor. Case 1: a) Anterior view. The vascular pedicle (arrow) and the muscle belly pass through the space between the urinary bladder and the pelvic wall. b) Right lateral view. The vascular pedicle (arrow) is connected to the common iliac artery and the flap through a linear course along the urinary bladder. c) Left lateral view. The urinary bladder and prostate gland are covered with the muscle belly of the flap. Case 3: d) Anterior view. The vascular pedicle (arrow) and the muscle belly pass through the space between the residual organs and the pelvic wall. e) Right lateral view. The muscle belly of the flap is located on the right side of the uterus. f) Left lateral view. The flap fills the dead space behind the urinary bladder and the uterus. Legends: Arrow, vascular pedicle; B, urinary bladder; U, uterus; M, muscle belly; F, flap.

Fig. 3

Operative findings (Case 3). a) A silicone tube is inserted through the intra-pelvic shortest pathway (asterisk). b) The vascular pedicle of the flap (arrow) and the preserved rectus abdominis muscle (arrowhead). The broad ligament of the uterus beside the urinary bladder is partially dissected. c) The posterior wall of the vagina and perineal defect are reconstructed with the cranial side of the flap.

Fig. 4

Schema of the intra-pelvic shortest pathway. a) After total pelvic exenteration, the intra-pelvic shortest pathway is horizontal to the abdominal wall. b) After posterior pelvic exenteration, the vascular pedicle of the flap is directed to the pelvic floor, which is vertical to the abdominal wall, to avoid the residual urinary bladder. c) The broad ligament of the uterus when the uterus is preserved in women with posterior pelvic exenteration. Legends: Arrow, vascular pedicle; B, urinary bladder; P, prostate; U, uterus; M, muscle belly; F, flap.