Voiding and sexual dysfunction are well-known complications after rectal resection for carcinoma, the main cause of which is injury to the autonomic nerves in the pelvis: the sacral splanchnic (parasympathetic) nerves and hypogastric (sympathetic) nerves [1-5]. These injuries may result from blunt pelvic dissection or undefined cutting during mobilization of the rectum.

As described by Heald in the 1980s, total mesorectal excision (TME) was introduced as the standard operative procedure for rectal cancer in combination with autonomic nerve preservation (ANP). Compared with conventional rectal cancer surgery, TME with ANP has been reported to reduce the incidence of complications of voiding and sexual function [3,6,7]. Despite the dramatic improvements in the surgical procedure for rectal cancer, the reported incidence of postoperative voiding issues and sexual dysfunction still ranges from 0% to 12% and from 20% to 50%, respectively [1,3,4,8,9].

Because of the early detection and advances in the treatment of rectal cancer, survival rates have improved, and it is expected that an increasing number of patients will be living with its sequelae. Therefore, quality of life after treatment is regarded as an important outcome in addition to the traditional endpoints, such as survival and recurrence. However, only a few studies have been published to date presenting an objective evaluation of voiding and sexual function after rectal resection. Most studies have assessed postoperative functional outcome at only one time point, rather than longitudinally.

This study aimed to evaluate the changes in male voiding capability and sexual function within a consecutive series of patients who underwent autonomic-nerve-preserving surgery for rectal cancer at our institution.

Of the total of 78 men who underwent TME with ANP for rectal cancer at the Korea Cancer Center Hospital between October 2005 and July 2007, 45 patients were evaluated preoperatively for genitourinary function. We retrospectively analyzed the data of 28 men who were followed up for more than 3 years.

All of the operations were performed by two surgeons (DYH and SMM), both being experts in technique and colorectal surgery. TME was performed according to the principles described by Heald et al [7], and the pelvic autonomic nerves, including the hypogastric nerve and pelvic splanchnic plexus (nervi erigentes), were preserved in all patients [10,11].

Preoperatively, all patients underwent urodynamic studies including uroflowmetry and filled out the International Prostate Symptom Score (IPSS). Voiding function was measured objectively with maximum flow rate (Qmax) and postvoid residual urine volume (PVR). Prostate volumes, measured by computed tomography (CT) before and after the operation, were compared.

We used the erectile function domain score on the International Index of Erectile Function (IIEF-EFD) and the ejaculation domain on the Male Sexual Health Questionnaire (MSHQ-EjD), both of which have been widely used, to evaluate sexual function. Erectile dysfunction (ED) severity was classified into 3 categories: normal, 26 or more; mild to moderate, 17 to 25; and moderate to severe, 16 or less. Patient characteristics, including age, tumor stage, tumor size, and type of operation, were recorded. The patients were followed after surgery by use of uroflowmetry and the aforementioned questionnaires.

Patients with recurrent or metastatic disease, a history of urinary tract surgery, prior rectal surgery, or no preoperative urodynamic assessment were excluded.

Statistical analysis was performed with SPSS ver. 12.0 (SPSS Inc., Chicago, IL, USA), using the paired Student's t-test and Wilcoxon signed-rank test. Data were considered to be statistically significant when the p-value was less than 0.05.

Postoperative voiding and sexual dysfunctions frequently develop after pelvic surgery. These complications result from thermal damage, ischemic injury, nerve stretching, and the local inflammatory effects to the hypogastric nerve and the sacral splanchnic plexus during pelvic dissection. Injury to the sympathetic supply results in detrusor instability and ejaculatory difficulties, whereas injury to the parasympathetic supply results in poor detrusor contraction and ED [1,7,10,12].

Even though comparisons between studies are difficult due to differing exclusion criteria and outcome measures, widely varying rates of voiding and sexual dysfunction after rectal surgery have been reported in the literature (Table 5). During rectal surgery, the ANP procedure causes less impairment of genitourinary function [8,13,14]. The functional benefits of ANP were confirmed in previous studies that evaluated the impact of ANP on rectal cancer by use of questionnaires [3,5,6]. Since the awareness of ANP, voiding complications appear to have diminished to a level of 0% to 4% [15]. For example, Nesbakken et al and colleagues reported that, when comparing results before and 3 months after the operation in 49 patients, rectal cancer surgery with pelvic autonomic nerve preservation showed no significant changes in voiding capacity [3]. Similarly, our study showed no significant complications related to voiding. Based on our data, rectal cancer surgery with ANP showed excellent preservation of voiding function; even 3 years after surgery, the results of the IPSS did not change significantly.

The transient decrease in Qmax might be explained by postoperative inflammatory changes in the perivesical tissues and the possible resolution of partial nerve damage with time, resulting in improvement and even complete recovery [13].

In contrast with the preservation of voiding function, sexual dysfunction remains a significant problem after rectal cancer surgery. Previous studies suggested that partial preservation of the pelvic autonomic nerves was sufficient to attain eventual functional recovery in voiding function [16,17]. The main cause of postoperative sexual dysfunction is intraoperative injury to the neurovascular bundles; partial dissection of the pelvic plexus can also affect sexual function [18].

Results of studies on male sexual function after rectal cancer surgery show impotence rates varying from 20% to 50% [3,9,13]. Ameda et al reported that postoperative ED was a serious complication, even in complete nerve preservation [18]. Hendren et al also reported that a high rate of sexual dysfunction is detected after rectal cancer excision, despite the use of nerve-preserving techniques [19].

The incidence of ED depends on the extent of resection, which may be reduced with nerve preservation [7,11]. In this study, all patients underwent bilateral ANP. The results of our study show that a significant proportion of rectal cancer patients suffer from sexual dysfunction after surgery. Overall, eight men (29%) experienced a complete loss of erectile function. These patients did not improve throughout the follow-up period. Therefore, it is likely that the crucial cause of postoperative sexual dysfunction is unrecognized nerve injury rather than neurapraxia. The intimate anatomic relationship of the superior hypogastric nerve, the bilateral inferior hypogastric plexus, and the bilateral cavernosal nerves to the rectum and prostate explains their possible risk of injury. The nerve damage might have occurred after the nerve to the bladder had branched off in the deep narrow pelvis where precise dissection may be more difficult. The high incidence of sexual dysfunction may be due to the vulnerability to nerve damage.

Although many factors influence postoperative sexual dysfunction, we could not determine a statistically significant relationship between sexual dysfunction and well-known adverse factors such as patient's age, stage, type of operation, smoking, chemoradiotherapy, and comorbidities because of the relatively small number of patients in this study.

With the relatively small number of patients and the retrospective nature of this study, our results are bound to be underpowered. Because the study population was "rectal cancer patients who are free of recurrence," the results may not be generalizable to all patients undergoing rectal cancer surgery. Despite the limitations of the data, however, the strength of our study is its long-term assessment with preoperative evaluation.

Preservation and maintenance of sexual function are guaranteed to be challenges to urologists in the future. In order to improve patient's quality of life, urologists will need to make an effort to detect patients who suffer from sexual dysfunction and treat them by cooperating and collaborating with surgeons. Also, patients need to be properly informed about possible adverse effects connected to the operation and how these adverse effects can be treated if they arise.

Although no standardized regimen exists, post-prostatectomy rehabilitation of sexual function or ED prophylaxis has become a common practice among urologists [20]. Interestingly, Lindsey et al reported that erectile function was satisfactorily improved by use of sildenafil (Viagra) only in 79% of male patients with ED after rectal excision for either rectal cancer or inflammatory bowel disease [21]. Likewise, baseline measurement and enthusiastic penile rehabilitation after rectal cancer surgery must be considered.

Voiding dysfunction after rectal cancer surgery and radiotherapy can be avoided in most patients by the preservation of pelvic autonomic nerves. However, although pelvic autonomic nerve preservation has been performed, a significant proportion of these surgical rectal cancer patients will still suffer from sexual dysfunction after surgery.

Larger prospective randomized comparative studies are necessary to confirm our results, which were limited because of the small number of patients. Urologists should investigate sexual function before surgery to generate meaningful outcomes for counseling patients before and after treatment, and penile rehabilitative treatment after rectal cancer surgery must be considered.