After the introduction of sacral neuromodulation (SNM), there has been a substantial decrease in the number of sphincteroplasties for anal incontinence (AI). Nevertheless, some patients still undergo the procedure, and a few even a second sphincteroplasty supported by two publications reporting good results (1,2). The aim of this study was to explore data from the Norwegian registry of anal incontinence (NRA) and investigate outcome in patients who had undergone one (group 1) or two (group 2) sphincteroplasties for AI. Primary endpoint was change in St Mark’s score between baseline and 1-year follow-up in the two groups.

A retrospective study of prospectively recorded data from the NRA. The registry has surveyed surgical treatment for AI in Norway since 2013. From 2015, all hospitals performing sphincteroplasty or SNM for AI are obliged to include the patients in NRA based on informed, written consent. The initial coverage degree of sphincteroplasties was 25% in 2013, while 62% of all patients who underwent the procedure in 2021 were registered in NRA. 

Baseline characteristics prior to surgery included age, menopausal status (if female), duration of symptoms, etiology, prior treatment for AI, endoanal ultrasonographic findings with defects of the external anal sphincter (EAS) and internal anal sphincter (IAS) measured in the mid-anal canal, St Mark’s score and Quality of life (QoL) score expressed as a simple visual analogue scale with 0 as worst imaginable and 10 as best imaginable QoL. All registered patients received a postal follow-up questionnaire 1 year after surgery including St Mark’s score and QoL score. 

Data was analysed with SPSS version 29.0 (IBM). Categorical variables were analysed with Chi-square test or Fischer’s exact test as appropriate, and continuous variables with t-test with confidence interval (CI). Correlation was determined with Pearson correlation test. Multivariable linear regression analysis was performed with change in St Mark’s score between baseline and 1-year follow-up as the dependent variable, adjusting for variables predicting change in St Mark’s score with p≤0.2 in univariable analysis using stepwise backward selection.

Between January 1st 2013 and December 31st 2023, some 146 sphincteroplasty procedures for AI were recorded. One patient with stoma at the time of repair was excluded. Some 45 patients did not return the follow-up questionnaires or respond when contacted by phone by the registry, and 4 patients were unable to fill out the questionnaire for other reasons. One patient withdrew the given consent, one had passed away and one had undergone implantation with SNM 7 months after sphincter repair and were excluded from follow-up in this study. Follow-up questionnaires were available for 93 (64.1%) patients, of whom 11 had undergone a second sphincteroplasty. Change in mean St Mark’s score between baseline and follow-up was 4.2 (95% CI: 2.8 – 5.6, p<0.001) for group 1 and 0.2 (95% CI: -4.5 – 4.9, p=0.933) for group 2.

St Mark’s score at baseline did not differ between the two groups, but at 1-year follow-up the difference was significant (mean 4.7, 95% CI: 0.7 – 8.8, p=0.021) in favour of group 1 (Table 1). The difference was even more significant when patients with etiology other than obstetric injuries and patients who had undergone concomitant fistula closure (altogether 8 patients) were excluded from analysis (mean difference 6.1, 95% CI: 2.0 – 10.2, p=0.004). 

There was a significant overall correlation between age and St Mark’s score at baseline (p=0.041) but not at follow-up (p=0.320). Furthermore, St Mark’s score at baseline was significantly higher in postmenopausal women compared to premenopausal (mean difference 2.2, 95% CI: 0.5 – 3.8, p=0.009), but not at follow-up (mean difference -0.1, 95% CI: -2.9 – 2.8, p=0.959). At Follow-up, general QoL was inversely correlated to St Mark’s score (p<0.001) and to change in St Mark’s score (p<0.001).

St Mark’s score at baseline in patients with defect in EAS only did not differ from patients with combined EAS and IAS tears (mean difference -0.4, 95% CI: -2.5 –1.6, p=0.674), but at 1-year follow-up patients with isolated EAS-defects prior to surgery had a lower St Marks score than patients with defects in both EAS and IAS (mean difference -3.1, 95% CI: -6.2 – 0.0, p=0.049). The group difference in St Mark’s score between baseline and 1-year follow-up, however, was not significant (mean difference 3.0, 95% CI: -0.2 – 6.1, p=0.067).

In multivariable linear regression with change in St Mark’s score between baseline and 1-year follow-up as the dependent variable and adjusting for variables with p≤0.2 in univariable analysis (age at repair, post-menopausal status at time of repair, previous sphincteroplasty, combined ultrasonographic EAS and IAS defect prior to repair, radial extent of EAS defect prior to repair, duration of symptoms prior repair and baseline St Mark’s score), only previous sphincteroplasty (p=0.025) and baseline St Mark’s score (p<0.001) remained significant after stepwise backward selection (table 2)

In contrast to patients who underwent first-time sphincteroplasty for AI, patients with a second sphincteroplasty showed no reduction in St Mark’s score after one year. Neither age nor menopausal status affected outcome. Reduction of St Mark’s score at follow-up was significantly associated with improvement in QoL. A higher baseline St Mark’s score was independently predictive of a greater reduction of St Mark’s score at 1-year follow-up, while previous sphincteroplasty was an independent predictor for lack of improvement.

Although the number of included patients is limited, data from NRA indicates that a second sphincteroplasty should not be undertaken if AI is the major reason for treatment.

Vaizey CJ, Norton C, Thornton MJ, Nicholls RJ, Kamm MA. Long-term results after repeat anal sphincter repair. Dis Colon Rectum. 2004 Jun;47(6):858-63 doi: 10.1007/s10350-003-0112-8. Epub 2004 May 4. PMID: 15129307
Bergh MR, Gregussen H, Sahlin Y. Long-term outcome of sphincteroplasty with separate suturing of the internal and the external anal sphincter. Tech Coloproctol 2019 Dec;23(12):1163-1172. doi: 10.1007/s10151-019-02122-7.Epub 2019 Nov 26. PMID: 31773346

Continence 12S (2024) 101475
DOI: 10.1016/j.cont.2024.101475