Rectus abdominis muscle flap in complex vesico-vaginal fistula repair: unique situation, uncommon option

Background Complex vesico-vaginal fistulae (VVF) pose unique surgical challenges and necessitate the use of inter-position tissue to ensure surgical success. Herein, we describe a case of complex VVF with right uretero-vaginal fistula post radical surgery for locally advanced ovarian cancer and chemotherapy in which the rectus abdominis muscle flap was used as the interposition tissue, as the more routine used options such as omentum and peritoneum were removed in the prior radical surgery. Case presentation We describe a case report of a vesico-vaginal and right uretero-vaginal fistula in a 34-year-old female post ovarian cancer radical surgery managed surgically with the traditional transvesical technique of repair and ureteric reimplantation with a unique interposition with rectus abdominis muscle considering the absence of the more routine options. Conclusion Complex VVFs pose unique surgical challenges and necessitate the use of interposition tissue to ensure surgical success. The inferior pedicle based rectus abdominis muscle flap is an excellent interposition tissue for repairs via the transabdominal approach especially in scenarios where the more routine options are unavailable.


Introduction
Complex vesico-vaginal fistulae (VVF) post oncologic pelvic surgeries pose a significant surgical challenge.These fistulas are frequently associated with injury to the adjacent pelvic organs such as the ureter and the patients would have received chemo-radiation in the postoperative period, thus hampering the blood supply and necessitating the use of an interposition tissue [1].VVFs post-surgery for ovarian cancer deserve a special mention, as a total omentectomy is performed as an integral step during its surgical management, thus removing the 'most suitable' interposition tissue.Herein, we describe a case of complex VVF with right uretero-vaginal fistula post-surgery for carcinoma ovary, in which the rectus abdominis muscle flap was used as the interposition tissue as the omentum was removed at the prior surgery.

Case presentation
A 34-year-old female was diagnosed with high grade serous carcinoma of the ovary with peritoneal carcinomatosis (Stage IIIC) for which she received 3 cycles of paclitaxel and carboplatin and underwent interval debulking surgery.Intra-operatively, there were dense adhesions between the uterus and ovaries forming a complex mass of 15 × 10 cm in size.There were also multiple peritoneal deposits, omental caking and diaphragmatic carcinomatosis observed and a total abdominal hysterectomy with bilateral salphingo-ophorectomy, supracolic omenectectomy and partial peritonectomy was performed.
On the 7th postoperative day, she started complaining of continuous leakage of urine per-vaginum which was managed conservatively.She recovered well from the surgery, except for the leakage of urine per-vaginum, and went on to receive 6 cycles of paclitaxel, carboplatin and bevacizumab.The patient had uneventful chemotherapy administration both in the neoadjuvant and adjuvant setting with side effects largely being minor such as nausea/ vomiting.A follow-up 18-fluorodeoxyglucose positron emission tomography scan was obtained post-completion of chemotherapy, which showed no evidence of metabolically active disease and she was referred to the department of urology for the management of a possible VVF.The time lapse between presentation and referral for surgery was approximately 6 months.She underwent local examination followed by a computed tomography, cystoscopy and right retrograde pyelogram (Fig. 1A, B) and was found to have 2 large supra-trigonal VVFs (4 × 4 cm and 2 × 2 cm, respectively), with one right at the right ureteric orifice, along with a right uretero-vaginal fistula and a long segment (3 cm) right distal ureteric stricture with right hydro-uretero-nephrosis.A per-cutaneous nephrostomy was placed on the right side and a combined study was performed to delineate the exact length of the stricture (Fig. 1C) and a cold cup biopsy was taken from the fistula margin to rule out residual malignant process, which was normal.
The patient underwent open transabdominal modified O'Connor's VVF repair and required a Boari flap for the right ureteric stricture, as the bladder was relatively small and densely adherent (Fig. 2A).Since the conventional interposition tissue, the omentum, was completely removed at the previous surgery, along with almost all of the pelvic peritoneum, a decision was made to use the rectus abdominis muscle as the interposition tissue.The belly of the rectus abdominis muscle was first separated from the anterior rectus sheath till its insertion in the ribs, where it was divided (Fig. 2B).As the majority of the posterior rectus sheath was already removed along with the peritoneum at the previous surgery, a small segment of the residual posterior sheath and the peritoneum, at the superior most aspect of the belly of the muscle over the posterior surface, was preserved to assist in suture placement and avoid cut-through.Post-transection, the blood supply was provided solely by the.inferior epigastric vessels (Fig. 2C), which were preserved and the muscle belly was rotated into the pelvis and the pre-placed sutures at the apex of the vagina, distal to the vaginal closure were passed through the part of muscle with posterior sheath intact.The muscle was then parachuted down between the bladder and the vagina as an interposition tissue (Fig. 2D).The anterior sheath was then approximated and the wound was closed after ensuring hemostasis.The postoperative course was uneventful.The per-urethral catheter was removed at 3 weeks, after obtaining a micturating cystogram which did not show any leak (Fig. 1D).The suprapubic tube was removed 5 days later and the right DJ Stent was removed at 6 weeks.The patient is currently on scheduled followup with no complaints of leakage or any lower urinary tract symptoms at the 3rd month follow-up.

Discussion
Interposition tissues in VVF repairs have always been an area of innovation, scrutiny and constant research.Much debate exists on their role and utility in repair of the primary cases, be it the transabdominal or transvaginal approach especially when the core principles of urogenital fistula repair are strictly followed [2].Tissue interposition is usually considered when the local tissue quality is questionable, as seen in complex fistulas of radiation induced or malignant etiology.Tissue interposition serves two important functions; one is the creation of an anatomical barrier between tissues of different nature and the second being the introduction of vascularity and lymphatics thereby promoting healing of the surrounding tissues [3].Most commonly utilized interposition tissue is the omentum owing to its robust vascular supply and immunogenic nature, hence naturally possessing excellent healing properties [3].Challenges arise when these common options are unavailable owing to prior surgical resection, getting the less popular options such as the gracilis flap [4], rectus abdominis flap [5], seromuscular intestinal flaps [6], labial myocutaneous or bladder mucosa flaps [7] into play.The most famous of these rare interposition tissues is the Gracilis muscle owing to its ideal close perineal location and versatility, thereby becoming a natural preference in perineal repairs with an added advantage of utility in genital reconstructions if needed concomitantly.
However, for a purely transabdominal approach, the inferior pedicle Rectus abdominis flap is a versatile muscular flap tissue with predictable blood supply ideally suited for challenging complex fistulae considering its location, mobility and excellent dependable and consistent blood supply.Donor site complications and flap loss are seldom observed with the only drawback is the theoretical risk of ventral herniation and the need for meticulous dissection between the abdominal layers, hence the need for surgical expertise [8].Published literature on the subject is rare and mostly limited to case reports owing to its extremely scarce utility.Reynolds et al., thus far, have published the largest account of RAM flap utility in 5 patients of complex VVF secondary to radiation and malignancies and reported an 80% success rate [9].

Conclusion
Complex VVFs pose unique surgical challenges and necessitate the use of interposition tissue to ensure surgical success.The inferior pedicle based RAM flap is an excellent interposition tissue for repairs via the transadbominal approach especially in scenarios where the more routine options are unavailable.

Fig. 1
Fig. 1 Imaging evaluations.A Diagrammatic representation of urinary tract findings (key in addition to marked ones-right distal ureteric stricture in dotted black line, vesico-vaginal fistulas in blue and respective fistula tracts in red).B Axial contrast section showing communication between vagina and urinary bladder (denoted by arrowhead).C Right nephrostogram and antegrade pyelogram revealing long segment distal ureteric strictured segment (denoted by arrowheads) and guide wire passing into vaginal cavity through right ureteric orifice introduction (denoted by *).D Postoperative micturating cystourethrogram showing no bladder leak and refluxing of contrast into the boari segment (denoted by arrowheads)

Fig. 2
Fig. 2 Intra-op photographs (leg end of the patient marked by * on the figures).A Post-transadbominal VVF repair with Boari flap reconstruction of right distal ureter (denoted by arrowheads).B Dissection of right rectus abdominis muscle off the anterior rectus sheath.C Transected right rectus abdominis muscle of its superior attachment based on inferior epigastric vessels (denoted by arrowhead).D Rectus abdominis muscle flap based on inferior epigastric artery (denoted by arrowhead) mobilized into the pelvis as interposition flap between urinary bladder and vagina