Pelvic Exenteration

Preoperative laboratory studies

Preoperative laboratory evaluations should include the following:

• Complete blood cell (CBC) count

• Comprehensive metabolic panel

• Coagulation studies

• Type and crossmatch for blood products

Because most patients have received previous treatment, including pelvic radiation therapy, an increased likelihood exists of preoperative anemia and, occasionally, neutropenia. A large number of patients also have poor nutritional status and electrolyte abnormalities. Other testing depends on the existence of other comorbid conditions in individual patients.

Preoperative imaging studies

The use of imaging studies in evaluating a patient for pelvic exenteration depends on the initial assessment of tumor size and location.

Most patients need a computed tomography (CT) scan of the abdomen and pelvis and a chest radiograph. For evaluation of potential areas that are suspicious for metastatic involvement, other imaging studies may be used as needed, including the following:

• Chest radiograph or CT scan

• CT scans of the abdomen and pelvis

• Magnetic resonance imaging (MRI) to evaluate musculoskeletal involvement, particularly in the assessment of pelvic side wall disease, as well as major pelvic vessel involvement in large lesions

• Liver ultrasonography to evaluate for metastatic disease

• Bone scan to evaluate for metastatic disease

Positron emission tomography (PET) scanning remains investigational in the evaluation of cervical cancer but may be very useful in excluding small areas of distant metastatic disease. A recent prospective study of fluorodeoxyglucose-18 (¹⁸ FDG)-PET scanning reported a sensitivity of 100% and a specificity of 73% in detecting extrapelvic metastasis before exenterative procedures in patients with recurrent cervical and vaginal carcinomas. ^[15]

Biopsy confirmation

Before proceeding with the surgical procedure, confirming a recurrence with a pathologic specimen obtained by biopsy is essential. Most cervical cancers are squamous cell carcinomas, although the incidence of adenocarcinomas of the cervix is rising. Rare histologic types are occasionally encountered and include adenosarcomas, uterine sarcomas, and cervical or vulvar melanomas. In patients who have previously had high doses of pelvic radiation, physical examination is notoriously unreliable, and bleeding and pain may be related to radiation changes rather than recurrent disease.

Psychosocial assessment

Psychosocial assessments of a patient's ability to adequately manage postoperative physical and psychologic issues may be needed. Assessment of comorbid conditions is especially important.

Prophylaxis and bowel preparation

An antibiotic and a mechanical bowel preparation are administered on the day before surgery. The stoma sites are marked on the skin before surgery. Prophylactic antibiotics are administered in the operating room, and pneumatic calf compression units are placed on the legs before the anesthetic induction. The potential operative field, including the entire abdomen, perineum, vagina, rectum, and thighs, is prepared and draped. Adequate vascular access must be available to ensure that rapid fluid and blood product resuscitation can be instituted if needed. Vascular access also allows invasive cardiovascular monitoring as indicated.

Patient positioning

The pelvic exenteration procedure is typically performed with the patient in the lithotomy position. The patient's legs are carefully placed in Allen or other supported stirrups. The correct positioning places the weight on the feet and includes padding to ensure protection from neurologic injury and to prevent compartment syndrome.

Exploration, evaluation, and identification

The patient undergoing pelvic exenteration is placed in the low lithotomy position, and through a midline incision, the abdomen and pelvis are thoroughly explored. The liver, peritoneal and bowel surfaces, aortic and pelvic nodal groups, and pelvic sidewall are carefully evaluated. Biopsies of any suspicious sites are obtained and examined by frozen section. Distant and peritoneal metastases are absolute contraindications to exenteration. ^{[8, 16]}

Controversy exists regarding whether to proceed in the presence of nodal metastasis, which reduces the survival rate to 5%, or direct tumor invasion of any adherent loop of sigmoid colon or small bowel. The issue of sidewall involvement is important in determining resectability, because the goal is to achieve negative surgical margins. In some centers, the availability of intraoperative radiation therapy (IORT) allows resection with close margins, ^[17] but grossly positive margins confer an extremely poor prognosis. The process of dissecting open avascular spaces allows for further determination of resectability with adequate margins.

The pararectal, paravesical, and Retzius spaces are developed under direct visualization, and the cardinal ligaments are isolated by this method. The pelvic retroperitoneal spaces are opened, and the ureters and internal and external iliac vessels are identified and tagged as necessary. This allows identification of pelvic nodal metastasis, dissection of the ureter, and visualization of vessels, which may require ligation to control or prevent excessive bleeding.

Total pelvic exenteration

After the hypogastric artery is identified and its anterior division or the uterine artery is divided, the cardinal ligaments are divided at the pelvic sidewall. This can be accomplished using endoscopic stapling devices. The ureters are dissected free of the lateral peritoneum and are clipped and divided, leaving as much length as feasible. The retrorectal space between the sigmoid and the sacrum and coccyx is developed. The sigmoid arcade and the superior rectal vessels are ligated. The sigmoid is then divided using a gastrointestinal assistant (GIA) stapler.

Supralevator exenteration

The rectum is lifted off the sacral hollow posteriorly using blunt and sharp dissection. The lateral attachments are freed using the endoscopic GIA. Anteriorly, the bladder is completely freed from the public symphysis, and the vesicourethral junction is identified. (The resection is thus carried en bloc to the level of the levator ani.) If a supralevator exenteration is adequate, the urethra is divided anteriorly; the rectum, posteriorly at the level of the pelvic floor; and the vagina, below the level of the tumor with adequate margins.

Infralevator exenteration

For the perineal phase, a second team of surgeons is usually involved. A total vaginectomy and urethrectomy is accomplished by making a circumferential incision inside the vulva; if necessary, resection of the anus is also incorporated. The vagina is dissected off the levator muscles unless they have tumor involvement. If this is the case, the muscle is excised to obtain an adequate margin. The rectovaginal space is developed from above and below, and lateral rectal pillars are divided. The rectum is divided using the GIA stapler at the level of the mid vagina (if a complete perineal resection is not being performed), and the specimen is thus freed completely and removed.

Reconstruction procedures

Reconstruction procedures that may be necessary as a result of pelvic exenteration include rectal anastomosis, such as end-sigmoid colostomy or low rectal anastomosis; continent or noncontinent urinary diversion; and vaginal and pelvic reconstruction.

Rectal anastomosis

The decision to perform an end-sigmoid colostomy or a low rectal anastomosis is based on the level of the resection, the length of the rectal stump, and the extent of other concomitant procedures. A low rectal anastomosis can sometimes be accomplished using the circular end-to-end anastomotic stapling device. ^{[18, 19]} Reports have evaluated the complications associated with a rectal anastomosis at the time of pelvic exenteration, and the overall incidence of anastomotic leaks or fistula formation is 30-50%. A protective colostomy or omental wrap has not been found to have a significant impact on the incidence of successful healing. In recent years, data have suggested that a higher leak rate occurs in patients undergoing concomitant procedures such as IORT and continent urinary diversions.

Urinary diversion

Several options exist for urinary diversion, and the choice of continent versus noncontinent urinary diversion is based on assessment of the patient's ability to care for a continent pouch and availability of the right colon and ileum with the ileocecal valve. ^[19] The best option for noncontinent diversion is an ileal urinary conduit in which the ureters are implanted in an isoperistaltic manner into a segment of small bowel, one end of which is brought out as a cutaneous stoma.

The continent pouch uses the right colon as a low-pressure reservoir, with the ileum, ileocecal valve, or appendix specially configured to create the continence mechanism. A variety of continent pouches with small variations have been described. ^[20]  A continent urinary diversion allows the patient to have only a single ostomy bag, or none at all, and it can be successfully accomplished in patients with gynecologic cancer.

Complications associated with both continent and noncontinent urinary diversions in women who are gynecologic oncology patients have been reported by several authors. Early complication rates range from 12% to 53%, and long-term complication rates range from 33% to 37%. The reoperation rate is 6-8%.

Late complications of both continent and incontinent reconstructions include vitamin B₁₂ deficiency, metabolic acidosis, ureteral stricture, and urolithiasis. The risk of urolithiasis may be higher in continent diversions. ^[21]

Vaginal reconstruction

Several methods for vaginal and pelvic reconstruction have been described. An omental flap can be accomplished, generally with minimal morbidity, and serves to carpet the raw exposed surfaces of the exenterated pelvis. Myocutaneous grafts, including rectus and gracilis muscle flaps, can be brought into the pelvis and perineum to create pelvic support and a neovagina. Split-thickness skin grafts have also been used to create neovaginas.

Outcome and prognosis

Reported 5-year survival rates after pelvic exenteration range from 23% to 64%. ^[22] The most common site of recurrence is the pelvis. Poor prognostic factors associated with recurrence after exenteration include tumor size greater than 3 cm, pelvic sidewall or resection margin involvement, nodal metastasis, and time interval of less than 1 year from previous radiation treatment.

Patients with cervical cancer have better oncologic outcomes after pelvic exenteration, compared with those who have other gynecologic malignancies that can be excised, such as vulvar and vaginal cancer. ^[23]

Complications of pelvic exenteration

The potential complications after pelvic exenteration are numerous. Almost every patient develops at least 1 complication, and approximately 40-50% experience a major complication that requires further diagnostic and therapeutic procedures. ^{[4, 5]} The operative mortality rate is 2-5% in modern series.

The major early postoperative complications include blood loss, sepsis, wound dehiscence, and anastomotic breakdown at the level of the bowel, urinary pouch, or ureteral sites. ^{[20, 24]}

The rate of late complications is lower, but approximately one third of patients experience fistula, bowel obstruction, ureteral strictures, renal failure, pyelonephritis, and chronic bowel obstructions. ^[20]

Other complications include deep venous thrombosis and pulmonary emboli, flap necrosis, and stomal necrosis.

The empty pelvis syndrome causes morbidity in up to 40% of patients who undergo pelvic exenteration, resulting in pelvic sepsis and perineal complications. ^[25]

A study by Matsuo et al found perioperative complication rates for minimally invasive pelvic exenteration (79.6%) were similar to the rates for open surgery (77.7%); however, a minimally invasive approach was associated with a lower incidence of high-risk complications, specifically sepsis and thromboembolism. The researchers noted that only 3.6% of women in the study had a minimally invasive pelvic exenteration. ^[22]