Sexual dysfunction is an important long-term risk of rectal cancer treatment, affecting both men and women. Autonomic nerve injury is a major contributing factor. Autonomic neuropathy can cause urinary dysfunction, erectile dysfunction in men, as well as retrograde ejaculation. Rates of these problems vary widely between studies, but most studies have found that erectile dysfunction is the most common autonomic nerve-related morbidity for men.[1]

Both sympathetic and parasympathetic nerve injury can result from proctectomy surgery. Sympathetic neuropathy caused by injury to the pelvic autonomic plexus at the sacral promontory causes ejaculatory dysfunction, usually manifested as retrograde ejaculation. This can be avoided by preserving the hypogastric nerve trunks, and by minimizing traction on the inferior mesenteric artery (IMA) pedicle and trying to leave a 1-cm margin at the root of the IMA during its division.

Parasympathetic injury, due to excessively lateral dissection along the lateral stalks or injury to the peri-prostatic plexus, can cause erectile dysfunction in up to 30% of men. With the anterior dissection during TME, except when resecting an anteriorly based tumor, it is important to preserve the integrity of Denonvillier’s fascia that is invested by the periprostatic plexus; injury to this plexus can cause additional parasympathetic injury and erectile dysfunction. Prior to the advent of TME, postoperative erectile dysfunction and retrograde ejaculation rates were observed in 25% to 75% of cases, however careful adherence to TME principles have decreased this to 10% to 29% of cases.[2]

Sexual manifestations of autonomic injury are less well understood in women, for whom dyspareunia is the most common sexual dysfunction symptom. Risks factors for sexual dysfunction include: abdominoperineal resection (APR), age over 65 years, radiation therapy, and the complication of abdominopelvic infection after surgery.[3]

Management of postoperative sexual function is multifactorial. Pilot studies of patients with neurogenic impotence after prostatectomy have shown that multi-disciplinary treatment, including sexual counseling and behavioral therapy, can demonstrate improvements in as soon as 6-12 months.[4] Following proctectomy, pharmacologic treatment with phosphodiesterase inhibitors, such as oral sildenafil, has been shown to improve sexual function in 80% of patients compared to 17% with placebo.[5] Other, less efficacious options include local intracavernous and intraurethral injections and vacuum-constriction devices. Couples counseling not only helps to reassure patients and their partners, but also can enhance response to medical therapy.[6] Ultimately, in the event of failure of behavioral and pharmacologic therapies, placement of a penile prosthesis is effective but irrevocable and should be considered only as a last resort.