Most reported literature on outcomes after sphincteroplasty for FI is based upon patient-reported satisfaction, grading scales such (i.e., modified-Parks Continence Score [12]), severity scales (i.e., CCFIS), and/or quality of life scores (i.e., FIQoL). Failure is usually defined as lack of improvement in FI symptoms, the need for reoperation for FI, and/or patient dissatisfaction. Overall, the short-term (<5 years) outcomes of sphincteroplasty have been considered favorable with excellent (no incontinence) or good (continence to flatus, some stain or urgency) in the range of 50–80%) [13–20]. Likewise, functional outcomes graded by the CCFIS have shown improvement in the short term [21, 22]. Unfortunately, long-term studies demonstrate that success rates deteriorate over time (>5 years) [13, 18–20, 23].

There are several studies reporting data after sphincteroplasty. In a retrospective study, Lamblin and coworkers [24] demonstrated in 23 patients that the CCFIS decreased from 12.7 preoperatively to 7.5 postoperatively. Overall, 17 patients reported being satisfied with their results, three (13%) expressed unsatisfactory or dissatisfactory outcomes, and three (13%) patients demonstrated early recurrence of FI symptoms. Both Maslekar et al. [14] and Lehto et al. [23] conducted prospective, observational studies in >50 individuals and they found patients experiencing deterioration in efficacy with time at term follow-up. For example, Maslekar et al. evaluated a group of patients with a CCFIS of 16 preoperatively. Postoperatively, the CCFIS score improved to five at 12-months of follow-up and subsequently seven at 84 months of follow-up. The authors reported an overall 80% surgical success rate. On the other hand, Lehto et al. [23] reported FI improved in 67% of their patients at short-term follow-up but after a longer follow-up the severity of FI was about the same as preoperatively. Barisic et al. [13] prospectively studied 56 patients with a preoperative CCFIS of 17.8. They found a significant improvement in CCFIS scores, four at 3-months of follow-up and six at 80-months of follow-up. Using the modified Parks grading system, 48% of patients had successful results and 42% experienced recurrent or continuing FI symptoms at the latest follow-up. Finally, Oom et al. and Bravo Gutierrez et al. conducted retrospective reviews of >120 patients with 10-year follow-up. In both studies, approximately 40% of patients reported satisfactory fecal continence (excellent or good results) and about 60% had continued FI symptoms or needed additional surgery for their symptoms. Interestingly, about 60% of patients were satisfied with their results due to patient-perceived improvement in FI episodes compared to preoperative baseline.

Anal manometry has not routinely been included in assessments of the efficacy of anterior sphincteroplasty. In most studies including manometric evaluations, no significant change in resting pressures has been reported [17, 18, 25]. Some studies also fail to demonstrate a significant change in squeeze pressures or sphincter length [18, 25], while another study found a postoperative increase in squeeze pressures and anal sphincter length [17]. A separate study demonstrated that preoperative anal manometry and PNTML measurements are not predictive of postoperative success [26].

The incidence of postoperative complications after sphincteroplasty is difficult to ascertain, as this has rarely been the primary study outcome when reported. Based on available data, it appears that the overall immediate postoperative complication rate ranges between 5 and 30%. The most common complication is postoperative wound infection, reported between 1 and 20% in different studies. In clinical practice, however, superficial infection that leads to opening up of the wound is rather common and these infections typically heal without further intervention [24, 27, 28]. The patient should be informed about this risk, however, since this will extend the healing time. Despite a fairly high rate of superficial infections that leads to the wounds to open up, the incidence of breakdown of the sphincteroplasty is rather uncommon. Some authors use a perineal drain, because of the infection risk, but there is not a proven benefit in the literature [29].

Perioperative events, such as deep venous thrombosis, pulmonary embolism and ileus, are rare [30]. Other reported complications include postoperative hematoma, prolonged perineal pain, UTI, and fecal impaction. Adverse functional events such as temporary urinary retention [21, 26, 31] and impairment in fecal evacuation requiring long-term use of laxatives and suppositories have been occasionally reported [21]. Some women report problems with dyspareunia [32–35].

SNS works by electrical stimulation of sacral nerve roots. Its exact mechanism of action is not clear. Studies indicate that FI may be improved by improved colorectal motility, improved rectoanal sensitivity, and spinal or supraspinal afferent inputs [38]. SNS therapy has demonstrated improved outcomes in a wide array of patient types. FI symptoms are improved in patient with or without sphincter injuries, patients with neuropathic fecal incontinence, cauda equina syndrome, and patients with low anterior resection syndrome [39–41].

According to a meta-analysis conducted by Tan et al. [42], SNS therapy has shown a statistically significant change in CCFIS and a significant increase in FIQoL scores subcategories. Success rates range between 55 and 80% with patients reporting improved decreased FI symptoms. About 30–40% report complete resolution of FI symptoms, while about 20% may have diminished efficacy of the treatment within 5 years [43–51].

SNS is associated with overall adverse event rate of 5–33%, but serious complications are rare [39, 48, 52–58]. Pain is the most common postoperative complication. Pain usually occurs at the site of implantation, but can also be experienced as extremity pain [46, 47]. To distinguish pain from sacral nerve stimulation versus pain from the device location under the skin, the device can be switched off. Resolution of symptoms indicates sacral nerve stimulation as the culprit of the patient’s discomfort. This pain can usually be alleviated by reducing the pulse width, changing the electrode configuration, or reducing the stimulation amplitude. Rarely, has the device been explanted for pain, although resitting the device may be necessary [47].

Wound infection may occur in up to 8–10% of patients [46, 47, 58]. An infection of the device or the lead, usually necessitates explant of the lead and stimulator and treatment with antibiotics. Patients can then usually be reimplanted about 3 months later when the infection has healed. Another local colication is hematoma, but this is quite rare.

There are some technical problems that may occur with SNS. Dislodgement of the unipolar test lead can happen, but this is less common with the tined lead electrode [59]. The neurostimulator generator is battery-operated and has a lifespan of 3–6 years if used for chronic stimulation [48].

Detailed instructions for troubleshooting have been well described by Dudding and coworkers [60]. A measurement of impedence provides valuable insight into a malfunctioning neurostimulator. An impedence of >4000 Ω indicates a technical failure of the implant or lead fracture, where as <15 Ω suggests a short circuit. In either situation, it is best to pursue surgical exploration to replace faulty components as a sacral radiograph is often nondiagnostic. At times, patients may complain of decreased or absent sensation of stimulation or require high-amplitude stimulation for sensation. If impedence measurements are normal, these findings suggest suboptimal lead placement or migration and significant lead migration will require replacement.

Maeda and colleagues [45] reported on 101 patients undergoing SNS in an observational study. They reported a total of 521 reportable events in 94 patients. The most commonly reported events were loss of efficacy (193 events, 37%) and lack of efficacy (141 events, 27%). A total of 422 events required reprogramming, such as changing electrode pole combinations, and/or stimulation amplitudes and switching the device on/off. Eight patients were lost to follow-up, 20 patients had their device removed (eight for loss of efficacy, six for lack of efficacy in which two also had pain, two for pain and discomfort, two for infection, one for a required MRI scan for an unrelated condition, and one was removed per patient request after a new colostomy formation for an unrelated condition. Four patients had their device permanently switched off because of loss of efficacy (two), lack of efficacy (one) and spontaneous improvement in FI symptoms (one).

To date, there are four clinical studies on magnetic anal sphincter. Two are single center, prospective observational studies [63, 64], one is a prospective comparison study with SNS [65] and one is a multicenter feasibility study [61]. Study results demonstrate an encouraging short-term benefit of ≥50% improvement in incontinence in approximately 70% of patients and there were improvements in both CCFIS and FIQoL.

Between the four studies, a total of 67 patients were selected for implantation of the MSA device, and there were 26 device-related adverse events reported. Two patients experienced intraoperative rectal perforation and had no device placed and one device was accidently cut during a separate procedure for rectal prolapse repair [63, 64]. The most common complication was wound infection (seven events; 15%) [61, 63, 64]. Four of the infections were accompanied with wound dehiscence and resolved with antibiotics. Two patients had the device explanted due to abscess or chronic infection. In one patient, although the infection resolved with antibiotics, the device was explanted per patient request for lack of efficacy. Perianal and gluteal swelling with erythema were reported in five patients in one study and resolved with conservative treatment [63]. Straining during defecation seems to risk cracking and self-expulsion of the MSA device and was observed in three patients [64, 65]. Three patients experienced fecal impaction which resolved with enemas and three patients experienced rectal bleeding which resolved spontaneously [61, 65]. Pain related to the device has been reported in two patients and resolved with medications [61].

In a systematic review of ventral rectopexy procedure for overt rectal prolapse, the authors report preoperative incontinence ranging between 23 and 93% in 191 patients [69]. Postoperatively, there was a statistically significant decrease in symptoms (FI ranging between 0 and 29%). This improvement corresponded to a significant decrease in CCFIS in two of the studies (the other four studies did not report pre-and postoperative CCFIS) [68, 70].

According to a systematic review by Gouvas et al. [69], the recurrent rate of rectal prolapse after ventral rectopexy is about 2–4% with an overall complication rate of 8.9%. In the studies reviewed, pelvic sepsis, pelvic hematoma, visceral erosion, mesh dislocation and infection occurred in up to 3% of patients. Port site infection or hematoma (1–6%) and port site hernias (0–7%) were observed. Other complications included urinary dysfunction and or infection, chronic abdominal pain, ileus, and cardiopulmonary complications.

The authors of a separate, retrospective review [71] of the safety of ventral rectopexy performed at five institutions reported their results on 2203 patients who underwent ventral rectopexy for rectal prolapse. Their most serious adverse event related to ventral rectopexy was mesh-related. Two percent developed mesh erosion and a majority of these patients presented within 36 months of the operation. Treatment of mesh complications varied from minor (51% had local excision of stitch/exposed mesh) to major (40% had either laparoscopic removal, removal with colostomy, or anterior resection) procedures. Eleven percent of patients developed non-mesh complications (e.g., port site hernias, urinary retention, or urinary tract infection, postoperative pain) with postoperative pain as the most common complaint. Conservative treatment was appropriate for most non-mesh complications. Four patients required pudendal nerve blocks for perianal pain and four patients were treated for anal fissures. Six patents required a diagnostic laparoscopy for pain symptoms.

To date, there is only one clinical study reporting results of for the vaginal bowel-control system [72]. All patients had ≥4 FI episodes over two weeks. Of the 100 patients fitted with the device, 56 patients entered treatment and completed follow-up after one month. 86% of patients experienced treatment success (≥50% reduction in FI episodes) at 1 month. At 3 months, 86% of 44 patients had >50% reduction in FI episodes and 72.7% had ≥75% reduction in FI episodes according to the last 2 weeks of their bowel diaries.

In the published study [72], there were no major adverse events associated with the vaginal bowel-control system. Minor complications amongst the 110 patients fitted for the device included pelvic cramping (15%), urinary incontinence/urgency (10%), vaginal symptoms (9%), pelvic pain (8%) and spotting (7%). At one month, the two most common symptoms were pelvic cramping (10%) and vaginal findings (5%). At 3 months, the only complaints were pelvic cramping (9%) and pelvic pain (3%).