Predictive factors for functional failure of ventral mesh rectopexy in the treatment of rectal prolapse and obstructed defecation

VMR is currently adopted by many surgeons as the procedure of choice for the treatment of internal and external rectal prolapse as well as symptomatic rectocele. The laparoscopic approach proved to be non-inferior to a laparotomic access in terms of functional outcomes and recurrence rates and may be superior in terms of morbidity [17, 18]. The incidence of prosthesis erosion is low and is more common after synthetic mesh placement [19]. Even in our study, the type of access, laparoscopic or robotic and the type of prosthesis used did not affect the functional results of rectopexy surgery.

In 24% of the cases, a preoperative rehabilitation treatment was attempted, without success. Rehabilitation is not currently recommended in clinical practice for the treatment of rectal prolapse [1, 5]. There are few published studies on the rehabilitative treatment of rectal prolapse, which suggest that it plays no role in the treatment of prolapse particularly in the presence of relevant anatomical abnormalities, either when constipation is present or when there is faecal incontinence [20]. Our study confirms this finding, since 23% of patients had had preoperative rehabilitation treatment, but still needed surgery. Moreover, there were no differences in the rate of preoperative rehabilitation between patients with effective surgical treatment and those with ineffective surgical treatment. In some patients, postoperative rehabilitation treatment was also performed when clinical and instrumental examination suggested the presence of a concomitant functional disorder of the pelvic floor as the cause of constipation. Interestingly, we observed that the effectiveness of postoperative rehabilitation treatment in reducing the risk of persistence or new onset of constipation after VMR (p = 0.034, Table 4). We hypothesised that in these patients rehabilitation may not effectively confer its intended benefit while the anatomical defect is still present. Once prolapse is corrected, the pelvic floor and sphincter muscles are relieved and might start to regain their normal function. Postoperative rehabilitation could be routinely applied to reduce the risk of persistent constipation.

The patients we analysed showed a significant improvement in defecation with a significant improvement in all the scores examined, except for the last item of the PAC-QoL questionnaire. The latter investigates the degree of patient satisfaction related to constipation and shows a slight improvement between pre- and postoperative, although it is not statistically significant (p = 0.0878). This finding, in contrast to the other scores, shows the possible gap between success measured with the specific score items and the patient's perception of the impact of the treatment on their overall quality of life.

Postoperative constipation was observed in 22 patients (36.1%), among which 3 (4.9%) had new-onset constipation, a slightly lower incidence rate than that in a review of different rectopexy techniques, which reported rates of new-onset constipation ranging from 5.5 to 10.55% for VMR [21].

Our study showed a reduction, although not significant, in faecal incontinence after VMR (p = 0.2152). On further analysis, we found a reduction in incontinence in patients who complained of it preoperatively, but we also recorded some cases of new-onset incontinence. This agrees with the results of previous studies [22, 23]. The improvement of continence can be explained by the elimination of intussusception, which caused inappropriate activation of the recto-anal inhibitory reflex, or by a reduction in incomplete rectal emptying [24]. Patients who did not improve after surgery may have had other underlying factors that caused faecal incontinence, such as anal sphincter insufficiency or neurological factors [25].

There are few studies in the literature that attempt to identify the causes of anatomical or functional failure of ventral rectopexy. A 2017 study analysed the recurrence rates of rectal prolapse after LVR surgery, focusing on the anatomical recurrence of prolapse. As in our study, Fu et al. analysed possible predictors of recurrence, highlighting preoperative alteration of pudendal nerve motor latency and use of synthetic prosthesis as significantly associated. Age, previous prolapse surgery, incontinence and preoperative manometric parameters were not predictive of recurrence [7]. Similarly, in a 2019 meta-analysis of 17 studies and 1242 patients, Emile highlighted male sex and prosthesis length of less than 20 cm as factors significantly associated with anatomical recurrence of full-thickness prolapse. Age, BMI, previous prolapse surgery, type of prosthesis used, duration of surgery, number of surgeons and conversion rate to open surgery were not predictive [8]. Only one published study examines surgical failure from the perspective of persistence of ODS symptoms [9]. The study showed that obstetric trauma and total number of deliveries do not influence the outcome in terms of constipation after VMR, whereas a higher BMI leads to an increased risk of anatomical and functional recurrence.

We also focused on recurrence in a clinical and functional sense, i.e. as persistence of constipation symptoms that brought the patient to the surgeon’s attention, or as new onset of symptoms. We tried to expand the range of possible risk factors analysed (Table 4). Compared to the studies mentioned above, the type of the prosthesis, male sex and BMI did not influence the clinical success of VMR for constipation in our case series. Consistent with the findings of Kremel et al., previous obstetric trauma and the number of deliveries did not influence the clinical outcome.

The most important parameter that is associated with an increased risk of clinical recurrence is the higher degree of prolapse according to the Oxford classification. In this case, however, the finding is to be correlated with an increased risk of prolapse recurrence, especially in major external prolapse, with a directly proportional relationship between prolapse extent (in centimetres) and risk of recurrence. It seems possible that the persistence of constipation in these patients is concomitant with recurrence or incomplete treatment of the underlying anatomical problem. On the other hand, the impact of prolonged and severe constipation due to multifactorial causes cannot be ignored, and the onset of prolapse and the worsening of its clinical manifestation that could be related as cause/effect.

Similarly, the presence of a redundant colon has been shown to be a risk factor for recurrence. Redundancy of the sigmoid colon was found on preoperative colonoscopy or intraoperatively. This is not surprising: according to guidelines, sigmoid resection can be added to posterior rectopexy in patients with prolapse and constipation [5]. Resection-rectopexy is a safe and effective procedure that achieves a better outcome in cases of constipation, especially in patients with a redundant sigma and a symptomatic sigmoidocele [26]. In 1992, a study showed that patients undergoing rectopexy alone had a higher pressure in the rectum for a given volume of isotonic sodium chloride solution introduced [27]. The authors hypothesised that this was due to a kinking between the redundant sigmoid and the rectum at the rectosigmoid junction. The addition of sigmoid resection could reduce this problem by avoiding the kinking that could be the cause of delayed passage of bowel contents. However, some studies have shown that although the functional results of resection-rectopexy are similar to those of VMR, but that postoperative complications might be greater [28,29,30,31]. The extent of colonic resection, method of mobilisation and rectal fixation vary considerably in the literature. Colectomy is usually not recommended in combination with repairs involving a prosthesis. However, some papers reported good functional results for resection-rectopexy procedures with ventral [32] or dorsal prosthesis placement [33, 34], albeit with higher morbidity rates. However, a procedure conducted with minimal contamination, irrigation of the pelvic surgical area, complete closure of the pelvic peritoneum and the use of a dorsally placed biologic prosthesis may reduce the risk of potential pelvic infections and complications.

The presence of constipation prior to prolapse also increases the risk of clinical failure. This finding confirms the multifactorial nature of constipation and ODS: even after correction of the anatomical defect, intestinal motility, hormone levels, psychological aspects and other factors can influence the patient's defecatory function. A 2014 study suggested that a significant number of patients presenting with rectal prolapse had an altered colonic transit time. Despite extensive resections of the entire left colon, the altered colonic transit could not be corrected, while some patients developed new-onset constipation [35]. In a defecographic study of rectal motility, obstructed defecation persisted after rectopexy, apparently due to the fixity of the rectum preventing effective expulsive contraction [36].

This study has several limitations: the retrospective and multicentric design, that did not allow standardization of follow-up, the limited number of patients, the absence of control groups and the involvement of both external rectal prolapse and ODS with internal rectal prolapse.

The treatment of constipation requires a multidisciplinary approach for a long period after surgery: about 20% of patients with ODS and 25% of patients suffering from anal incontinence have persistent symptoms and still seek help [37]. Currently, there is no evidence indicating what the optimal treatment after failure of VMR might be, but it is mandatory to study accurately the patient and their clinical presentation before choosing the treatment.

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