Changes in anorectal physiology following injection sclerotherapy using aluminum potassium sulfate and tannic acid versus transanal repair in patients with symptomatic rectocele; a retrospective cohort study

Several patients with chronic constipation require medical treatment. However, patients with rectocele can easily be treated surgically [1, 2], suggesting that research investigations may yield a significant outcome. Rectocele is a disease, in which the anterior wall of the lower rectum and posterior vaginal wall are curved and protrude into vaginal canal due to defective or weak rectovaginal septum [3]. Enlarged rectocele and functional disability may result in retention of the feces in the rectum. In this case, insertion of finger into the vaginal wall may facilitate the excretion of the feces by pushing them down the rectum in some patients. Rectocele was found in 20–81% of normal female population [4‐7], and 23–70% of patients with rectocele showed symptoms such as constipation, suggesting unclear relationship between this anatomical disorder and symptoms of rectocele [8, 9]. Current treatment methods for rectocele include transanal rectocele repair (TAR) [10‐12], posterior colporrharphy [13], transvaginal repair using Marlex mesh [14], and laparoscopic transabdominal approach [15]. However, physicians select the treatment method based on their familiarity with specific procedures [16] in the absence of robust evidence supporting individual treatments or comparative analysis of different treatments. Recently, injection sclerotherapy using a combination of aluminum potassium sulfate and tannic acid (ALTA) has been reported as a possible treatment for rectocele because of its simplicity, low percentage of complications, and lack of apparent signs of pain [17]. Unfortunately, studies investigating anal physiology are lacking.

In this study, patients with rectocele were divided into two groups: TAR and sclerotherapy using ALTA (ALTAS). Following these treatments, changes in anorectal function were analyzed using anorectal manometry and defecography to obtain comparative results and determine the significance of ALTAS.

Rectocele has always been considered as a gynecologic problem. It was not until 1968 when Sullivan et al. [12] introduced TAR that rectocele was considered as another type of chronic constipation amenable to anorectal surgery. Recent advances in anorectal physiology elucidated the factors underlying the increased size of rectocele and the inability of the rectocele to promote defecation in the direction of the anal canal during defecation. Instead, defecation is diverted towards the weakened rectovaginal septum and additional push is needed for excretion, which enlarges the rectocele [8]. The rectocele can be examined by physical examination digitally using anal finger. However, the significance of rectoceles that are larger than 2 cm is disputed [7, 24], with a few experts suggesting that the size is not correlated with the symptoms [25‐27]. These disagreements highlight several controversies floating around regarding the relevance of rectocele size and symptoms. Therefore, several clinicians are uncertain regarding the appropriate timing for surgery and the specific surgical intervention that is most appropriate.

Anatomical and physiologic studies of rectocele are essential to address this challenge. As the CSS level decreased pre-A, post-A and pre-T, post-T, the rectocele size was significantly reduced in defecography. The treatment effect was sustained without any significant differences between the two groups in CSS testing, suggesting that ALTAS is an effective intervention for the management of rectocele. Additionally, in defecography, a significant increase was observed in anorectal angle under exertion. Another significant increase occurred in perineal descent after surgery compared with pre-surgical level. Van Laahoven et al. [2] interpreted that the size of rectocele shifted the vector force of defecation in a physiological direction post-operation. In anorectal manometry, which is used to determine the physiological changes, the MRP indicating the functionality of internal sphincter muscle, and MSP indicating the function of the external sphincter muscle, were significantly lowered postoperatively. This result was attributed to damage of anal muscles due to anal retractor, which is used during TAR. In addition to the effect of anatomical correction, surgery also improved the rectal sensation in both ALTAS and TAR, which significantly lowered the ST, EDU, MTV, and rectal sensation post-surgery.

Currently, treatments such as TAR [10‐12], posterior colporrpaphy [13], transperineal repair, which uses Marlex mesh [14], and laparoscopic transabdominal approach [15], stapled transanal rectal resection (STARR) [28] are used to treat rectocele. TAR, which is an operative method used by many coloproctologists, has been used to treat anal diseases such as hemorrhoids, mucosal prolapse, and complete rectal prolapse, simultaneously [29]. However, the disadvantages of TAR related to its inability to treat vaginal disease in addition to increasing the risk of complication associated with vaginal tightness [30]. Posterior colporrhaphy, used by several gynecologists can be used to treat urological or gynecological disease at the same time. However, it cannot be used to treat anal disease, and is associated with extreme postoperative pain and complications of vaginal strictures [13]. Transperineal repair, which uses Marlex mesh, is a new treatment modality that has a theoretical advantage of recovery of anatomical function by attaching the prostatic patch to the anatomically defective area. However, this treatment leads to fibrotic tissue formation and associated pain as well as perineal pain and dysuria [14]. Other disadvantages include prolonged scar healing, increased discharge, and continuous administration of antibiotics [21]. Laparoscopic transabdominal approach is indicated for cases of relapse or when rectal intussusception accompanies rectal prolapse. However, it is a larger procedure compared with other surgeries [15].

Longo came up with STARR for patients diagnosed with obstructed defecation through rectocele and intussusception. While STARR was very effective in improving the rectal symptoms related to rectocele and intussusception, it was associated with complications [28]. The postoperative bleeding rate ranged from 3.3 to 26.6%, and fecal urgency rate ranged from 1.1 to 34%, while incontinence to flatus rate ranged from 6 to 26.7%. The recurrence rate was less than 40% [31, 32].

Injection sclerotherapy is indicated for hemorrhoids and rectal prolapsed. It is minimally invasive and economical, but seldom used to treat rectocele [33]. ALTA treatment interrupts the blood flow to the hemorrhoids resulting in sporadic hemostatic effect and contraction of hemorrhoids. Eventually, sterile inflammation induces persistent fibrosis. Further, attachment and fixation of submucosal layer and mucosa to the muscular layer is promoted. Finally, bleeding of hemorrhoids is stopped and the prolapse is resolved [34].

Abe et al. [17] reported injection sclerotherapy as a treatment that is easy, rapid, and shows fair mid-term results. More importantly, it is associated with a low rate of complications. Another advantage of ALTAS is that it does not need suturing or excision, unlike transanal procedures. The treatment is not associated with the risk of anastomotic dehiscence or bleeding, and can be performed rapidly under local anesthesia, without any postoperative complications such as rectovaginal fistula or infection and alleviates postoperative pain. ALTAS can be used to treat hemorrhoids, rectal intussusception, and mucosal prolapse, which are concomitant anorectal diseases, simultaneously. ALTAS, using the Z-type proctoscope, provides effective access to high rectoceles as well [17].

Complex internal muscle control such as nerve plexuses, muscle, colon and pelvic floor activity and various chemical and hormones play an important role in normal defecation [35]. Therefore, psychologic factors, long-term idiopathic constipation, and hormonal disorders can have a huge impact on defecation impairment [2]. Rectocele, which is one of the main causes of defecation disability, is an anatomical abnormality suggesting that surgery that reduces the size of the rectocele effectively improves the symptoms. However, even though the size of the rectocele is reduced after the surgery, it does not completely disappear, which suggests that the relationship between postoperative anatomical correction and symptom improvement is still unclear [36]. Our study has shown that both treatments significantly improved the rectal sensitivity, consistent with Van Laarhoven et al. [2]’s findings suggesting that the significantly reduced size of rectocele post-treatment alters the vector force in the normal, physiological direction. However, the concept of physiological changes in improving rectal sensation along with the underlying mechanism needs to be explored further.

Both ALTAS and TAR effectively reduced the size of rectocele, which resulted in alleviation of symptoms such as constipation. It is believed that these two treatments had additional effects beyond reducing the size of rectocele. ALTAS and TAR treatments appear to show synergistic effects such as alleviation of rectal sensation and altering the push phase of the bowel movement in the physiological direction. Additionally, ALTAS treatment was a feasible option for effortless and rapid as well as long-term outcome, with low rates of complications, and it represents a substitute for patients with symptomatic rectocele.