Perspective Chapter: Obstructed Defecation – From Diagnosis to Treatment

Abstract

Obstructed defecation is a common, disabling condition, with significant crossover to other functional gastrointestinal disorders as well as pelvic floor problems. It requires a comprehensive assessment as it involves functional, behavioural, psychological and anatomical aspects. This chapter will address the broad aspects of obstructed defecation including an in-depth discussion of concepts of normal and abnormal defecation, pathophysiology, and appropriate use of investigations. A summary of nonoperative therapies including biofeedback and irrigation will feature, along with an update on the evidence for surgical options in obstructed defecation.

1. Introduction

Obstructed defecation is a widely accepted term used to define the symptoms of anorectal outlet obstruction; it is a symptom complex and not a diagnosis.

Despite the Rome IV criteria classifying functional defaecation disorders, there is currently no specific accepted strict definition for obstructed defecation; the most widely used criteria, however, are those defining the subset of functional constipation in Rome IV [1]. These include two or more of the following occurring in more than 25% of defecations:

1. Straining

2. Lumpy or hard stool

3. A sensation of incomplete evacuation

4. A sensation of anorectal obstruction or blockage

5. Manual manoeuvres to facilitate defecation (e.g. rectal/vaginal/perineal support).

The other components for a diagnosis of functional constipation include less than three spontaneous bowel movements per week and the absence of or infrequent loose stool without the use of laxatives.

To make a diagnosis of a functional defaecation disorder, patients must also have objective evidence of impaired evacuation in two of the below tests:

1. Abnormal balloon expulsion test.

2. Abnormal anorectal evacuation pattern with manometry or anorectal EMG.

3. Impaired rectal evacuation by imaging.

2. The symptom complex and associated problems

Obstructed defaecation can be an extremely debilitating condition with frequent coexisting and associated symptoms. Presentation is often delayed due to embarrassment or a perceived lack of treatment options. It is a chronic problem, well established in having a significant impact on quality of life, with some experiencing severe symptoms interfering with their daily activities or social functioning. The impairment is at least as significant as medical chronic conditions such as diabetes, depression and neurological diseases [2].

Many patients report abdominal pain and/or significant bloating, and potentially even nausea or food avoidance, and often this is their main complaint [3]. This can divert attention away from outlet obstruction symptoms and lead to a diagnosis of irritable bowel syndrome (IBS), which currently has a different treatment algorithm. It is now becoming increasingly recognised, however, that functional constipation and irritable bowel syndrome are a spectrum of disease, rather than entirely distinct entities, as per the update to Rome IV [4]. Essentially, the diagnostic criteria between irritable bowel syndrome with constipation (IBS-C) and functional constipation are very similar, differing only in the presence of abdominal pain in IBS-C. A 2021 cohort study using machine learning to compare patients with functional constipation and IBS-C supported the concept of the two disorders being a one-dimensional spectrum rather than two disparate diseases [5]. Mechanistically, this is plausible, with an outlet/emptying disorder likely to lead to a high-pressure colon and visceral pain, although IBS may feature additional visceral hypersensitivity requiring other modes of analgesia [3].

There is a significant crossover between symptoms amongst functional gastrointestinal disorders, with more than one third of patients having symptoms overlapping with another disorder [6] as alluded to above. The clinician should obtain a complete pelvic floor history as well as screening for symptoms of irritable bowel syndrome, which often coexist. In general, symptomatic relief is the primary goal of treatment along with improvement in quality of life, and treatments that are known to be effective for functional constipation have been shown to improve quality of life and symptoms in IBS-C [7]. Therefore, the distinction or segregation between these functional gastrointestinal (GI) disorders is less clinically relevant.

Over half of all patients presenting to a pelvic floor unit with functional constipation will also have symptoms of faecal incontinence. This may include passive faecal leakage or urge incontinence, and the coexistence of symptoms is missed by over 85% of referring clinicians [8]. In fact, the progression of longstanding obstructed defaecation to faecal incontinence is widely acknowledged, and an area of ongoing longitudinal research—these patients often have signs of mechanical dysfunction including perineal descent [9], presumably from excessive straining over years.

With the multicompartment nature of pelvic floor disorders, it is also important for the clinician to uncover symptoms of vaginal prolapse and urinary symptoms such as incomplete voiding or urinary incontinence, often related to the same underlying pathophysiology.

A history of sexual abuse can be important to appraise as only 17% of victims disclose this history to their doctor, and a psychologist or psychiatrist is an important member of the multidisciplinary team supporting these people [10]. There is a strong association with functional gastrointestinal disorders and chronic pain and those with constipation may have worse symptoms and quality of life [11], although anorectal physiology findings are similar to those without this history [12].

Haemorrhoids are also a common complaint in patients with obstructed defaecation along with rectal bleeding. Amongst patients undergoing haemorrhoidectomy, a Saudi Arabian study found 24.2% had obstructed defaecation syndrome and this was shown to have a negative correlation with postoperative patient satisfaction [13]. A Chinese study also showed that a higher obstructed defaecation score was significantly associated with recurrence of haemorrhoids postoperatively and less satisfaction with surgery [14]—both studies supporting the importance of treating the underlying defaecatory disorder, along with its consequent haemorrhoids.

3. Prevalence and epidemiology

The precise epidemiology of obstructed defaecation is poorly understood because there is no unified definition of the syndrome. The literature varies widely depending on the definition and the population studied, but its prevalence estimates range from 2 to 30%. It is particularly prevalent in multiparous postmenopausal women and more frequently observed after hysterectomy [15].

An Australian population-based study using market research analysed the prevalence of functional constipation [16]. In 2376 respondent’s representative of the Australian population, 24% had chronic functional constipation based on Rome III criteria and 59% self-reported constipation in the last 12 months. The most common symptoms participants described were straining, hard stool and the feeling of incomplete evacuation, with each reported by about 80% of those with constipation.

4. Normal and abnormal defaecation

An understanding of obstructed defaecation first requires an appreciation of the mechanism of normal defaecation.

Normal defaecation requires the following:

1. The delivery of soft-formed stool to the rectum.

2. Normal cognitive/behavioural elements in toileting and normal childhood defaecatory acquisition.

3. Psychosocial aspects including access to toilets and appropriate response to the call to stool.

4. Dietary aspects/gastrocolic reflex.

5. Colonic motor activity and propulsive force.

6. Rectal and anal compliance/elasticity.

7. Intact neural pathways.

8. Intact pelvic supports.

9. Normal coordination of the abdominopelvic cylinder during the defecation manoeuvre.

Normal defaecation is a complex mechanism with functional, physiological and psychosocial elements.

The delivery of soft-formed stool to the rectum is achieved with an intact colon with normal transit. In general, fibre supplementation is a useful adjunct to optimising stool consistency and a routine part of assessment, using the Bristol stool chart. The assistance of a dietitian can be invaluable.

The development of a normal defaecatory reflex occurs during early childhood but is poorly understood. Certainly, the effect of childhood physical, emotional and sexual abuse cannot be underestimated during this critical time of neuroplasticity [10]. Problems often initially manifest as paediatric GI disorders, with people going on to continue to suffer with symptoms into adulthood.

Issues with toileting behaviour such as a timely response to the call to stool, and access to toilets, form the basis for a lot of the intervention that pelvic floor physiotherapists make. Psychological stress or distress may lead to disordered defaecation and avoidance of public/school toilets [17] and other lifestyle or vocational issues may disrupt a normal toileting pattern. These are often underestimated and understudied elements of defaecatory dysfunction that can be easily addressed.

A normal defaecatory manoeuvre requires coordinated movement of the entire abdominopelvic cylinder and anal opening, with complex dynamic muscular changes in the pelvis to facilitate a smooth, effective evacuation. A proctographic study of 20 females demonstrated a bidirectional pull on the anal canal during defecation, with the posterior wall of the anorectum moving posteriorly and the anterior wall moving ventrally, thereby increasing the anal canal to twice its diameter during defaecation, mechanistically facilitating evacuation [18]. The musculoelastic theory of defaecation suggests that the passive contraction of the puborectalis muscle against the opposing pull of the levator plate maintains the anorectal angle, and thereby continence. During defaecation, puborectalis relaxes, but the pubococcygeus muscle contracts, pulling the anterior rectal wall open against the opposing contraction of the levator plate, which can now pull the anorectal wall posteriorly, unopposed. This theory would be concordant with the observed changes during normal proctography and result in less resistance to faecal flow [19]. Normal defaecation may therefore involve both relaxation and activation components in pelvic floor muscular activity.

Effective pelvic floor muscular function also requires integrity to its ligamentous supports. A large European multicentre prospective series of over 650 females with coexisting vaginal apical prolapse and other pelvic floor symptoms underwent a gynaecological transvaginal surgery, with reconstruction of the uterosacral and cardinal ligaments [20]. Amongst those with faecal and urinary incontinence, there was a statistically significant improvement in symptoms with this gynaecological surgery, illustrating the importance of these ligaments in anorectal and bladder function. A retrospective study also demonstrated an improvement in anorectal function with transvaginal surgery for vaginal prolapse (sacrospinous fixation), including a statistically significant improvement in the obstructed defaecation and constipation scoring system scores [21]. These studies support the concept of pelvic ligamentous integrity being an important element of normal anorectal function (Figure 1).

Figure 1.

Normal pelvic anatomy (left) and mechanical pelvic floor dysfunction with loss of pelvic ligamentous integrity (right) (illustrated by Joyce El-Haddad).

The gradual progression in grades of rectal prolapse that has been previously demonstrated [22] leads to high-grade internal rectal prolapse with potential plugging of the anal canal, causing obstruction of defaecation. With a loss of fascial supports also comes a loss of effective force vector for push, with this dissipating into a rectocoele or causing loss of pelvic floor mechanical advantage. About 74% improvement in obstructed defaecation observed with rectopexy surgery [23] again supports the concept of a restoration of rectal supports improving obstructed defaecation in some patients due to an improvement in the mechanics of defaecation (Figure 2).

Figure 2.

Mechanical pelvic floor dysfunction with high-grade internal rectal prolapse (illustrated by Joyce El-Haddad).

Another very important element in normal defaecation is normal coordination of the defaecatory manoeuvre. Dyssynergia refers to a lack of coordination of the abdominal and pelvic floor muscles during defaecation, leading to an inability to evacuate stool. This affects approximately 50% of all constipated patients [24]. The elements of dyssynergia include the following [25]:

1. Inadequate rectal propulsion.

2. Paradoxical anal closure.

3. Inadequate anal opening.

4. Impaired rectal sensation.

Dyssynergic defecation remains controversial, but is considered an entity in the Rome IV criteria [1]. It is common and has a significant effect on quality of life, with the majority of patients being female [25].

Many patients with dyssynergia describe straining and incomplete evacuation, but abdominal pain and bloating are also frequent symptoms [25]. There is a high rate of physical and sexual abuse in this cohort [26]. As a cause of chronic functional outlet obstruction, it can be associated with slow colonic transit in longstanding cases, particularly when constipation goes back to childhood or where there is laxative dependence [27]. As with the other causes of obstructed defaecation, there is a significant overlap with IBS features and in fact, IBS patients benefit similarly from biofeedback therapy to patients with isolated dyssynergia [7]. Biofeedback therapy has also been shown to improve transit time in patients with defaecatory disorders [28], making evaluation and treatment for dyssynergia in constipated patients important.

The majority of patients with obstructed defecation have a combination of both anatomical and functional derangements—requiring a cautious approach and judicious use of investigations. Excessive pressures from straining and ineffective defecation may lead to stretching of supportive tissue and prolapse; equally impaired mechanics and loss of pelvic supports from obstetric trauma or surgery may lead to straining to better effect defecation. A vicious cycle of excessive straining may then lead to further deterioration—perhaps explaining the gradual progression from pure obstructed defecation to that combined with faecal incontinence (Figure 3).

Figure 3.

Concepts in the pathophysiology of obstructed defecation.

5. Investigations for obstructed defecation

The assessment of obstructed defecation serves the purposes of both facilitating diagnosis and treatment, as well as exclusion of other pathology, albeit rare. There are no studies to guide the clinician but in general, blood tests including screening for biochemical or metabolic disorders are acceptable, including full blood count, renal and thyroid function and serum calcium [29]. The astute clinician will keep an open mind in considering other diseases such as cauda equina syndrome or neurological/endocrine disease, which may masquerade as obstructed defecation.

A digital rectal examination is mandatory and can be used to both exclude local disease and evaluate during dynamic movements for the presence of rectocoele, haemorrhoids and prolapse.

The yield of colonoscopy in this cohort is low, although an endoscopic assessment can provide reassurance and will often diagnose adenomatous polyps, although at a rate similar to the general population [30].

Colonic transit studies aim to distinguish slow transit from obstructed defecation and require the patient to come off laxatives for the study. The diagnosis of slow colonic transit may lead to treatment options such as stimulant treatment or surgery, but slow transit also improves with biofeedback therapy [28], a mainstay of treatment for obstructed defecation. Transit studies should therefore be deferred until patients have had biofeedback, and slow transit has not been shown to affect the results of surgery for obstructed defecation [31].

Anorectal manometry has not been validated for its role in the workup for obstructed defecation, but remains an extremely useful tool in the investigation of obstructed defecation. Widespread variance in practice has led to the International Anorectal Physiology Working Group providing a consensus statement regarding the role of physiological tests in anorectal structure and function, and a protocol for performing anorectal manometry [32]. Certainly, anorectal physiology tests are well tolerated by patients, and can direct treatment including diagnosis of altered rectal sensation, hypotonia, dyssynergia and an absent recto-anal inhibitory reflex, which could lead to consideration of Hirschsprung’s disease [33]. It is recommended as a comprehensive evaluation of anorectal function by the European Society of Neurogastroenterology and Motility guidelines on functional constipation [34].

Proctography, either fluoroscopic or magnetic resonance, allows a dynamic assessment of anorectal function and is considered the current “gold-standard” in the diagnosis of high-grade internal rectal prolapse. It also assesses for other pelvic floor anatomical abnormalities such as enterocoele, cystocoele and vaginal vault prolapse. The presence of an enterocoele predicts a good response to ventral mesh rectopexy and therefore adds clinical utility to this test [35]. A Cochrane review reported an 89% sensitivity and specificity of 92% for the diagnosis of rectal prolapse, although this did not separate internal and external rectal prolapse and include low-grade internal rectal prolapse, generally not considered clinically relevant [36]. Similar to anorectal manometry, wide variations in reporting have led to a consensus statement regarding the performance of proctography, with this report acknowledging the results are often dependent on patient and radiographer factors [37].

The role of an examination under anaesthetic in the diagnosis of rectal prolapse, which may detect occult high-grade internal rectal prolapse in a false-negative proctogram, requires further evaluation [38].

6. Non-operative therapies

A holistic approach to obstructed defecation, with identification of both anatomical derangement and functional and behavioural contributers, is important and more likely to lead to symptom improvement. Overall, treatment should be targeted at symptoms and aimed to improve quality of life, rather than correcting anatomy or proctographic abnormalities.

The benefit of a multidisciplinary approach to functional constipation has been shown over single specialist care [39], with initial treatment including dietary modification, laxatives/medication, psychological therapy and pelvic floor biofeedback.

Fibre has the benefit of potentially modulating gut dysbiosis as well as achieving a softer, more manageable, stool consistency. Most evidence for fibre supplementation is behind soluble fibre, such as psyllium husks; however, its use can be limited by the development of bloating or abdominal pain in those with IBS-C symptomatology [40]. In some patients, particularly those with coexisting slow transit, reducing fibre improves symptoms [41, 42].

The input of a dietitian can provide expert advice and is common practice, although there is not much evidence supporting dietetic intervention in obstructed defecation. An Australian study pooled 126 patients referred to a colorectal pelvic floor clinic, 44% of whom presented with obstructed defecation, to dietitian-led input including a healthy eating programme and fibre supplementation. Overall, 25% of the 126 patients had complete resolution of symptoms, with a high degree of satisfaction [42]. Dietitians are also more likely to recognise patients who have an eating disorder, with 24% of these patients suffering from functional constipation [43].

Exercise and fluid intake are also considered part of basic management, although again there is paucity in the literature to support this. A NICE review from 2021 found only low to very low-level evidence supporting exercise, fluid intake and dietary intake measures in preventing pelvic floor symptoms, and there were no studies on obstructed defecation specifically [44].

In terms of laxative therapy, there have been more placebo-controlled trials over the last 15 years and a recent systematic review showed the strongest evidence base in treatment of constipation with polyethyene glycol and senna [45]. Docusate, a commonly prescribed laxative, had no recommendation as there is surprisingly little evidence for its use, with no clinical studies published since 2004.

Psychological therapy may have a role in those patients with IBS-C symptoms, with systematic reviews demonstrating improvements in IBS symptoms, particularly with cognitive-behavioural therapy and gut-directed hypnotherapy [46]. As the crossover between IBS and functional constipation is more recognised, these therapies may play a role in improving quality of life in obstructed defecation patients.

7. Biofeedback therapy

Specialist pelvic floor physiotherapists with further training in defaecatory physiotherapy are able to provide a holistic approach to optimising lifestyle around toileting and defaecatory technique. This includes the timing of defaecation, improving lifestyle measures pertaining to toileting, dietary advice and laxative advice. Specifically, positioning and toileting technique are improved. There is evidence that the “squatting” technique for defaecation leads to a better evacuation, hence the benefit of using a stool when on a Western toilet [47].

Biofeedback therapy refers to reinstitution of a more “normal” defaecatory technique with the use of visual feedback to the patient. Expert physiotherapists are also able to perform volumetric rehabilitation to treat altered sensitivity in the rectum.

A randomised study comparing biofeedback therapy and polyethylene glycol for obstructed defaecation showed an improvement in clinical symptoms in the biofeedback group [48]. There is randomised evidence for a benefit over standard care in pelvic floor dyssynergia [28] and an improvement in constipation symptoms and patients with internal rectal prolapse [49]. Long-term follow-up from the well-known Poppy trial has shown that patients who underwent pelvic floor physiotherapy treatment were less likely to require hospital treatment for pelvic floor disorders such as faecal incontinence for a period of over 10 years [50].

The benefits of specialist pelvic floor physiotherapy cannot be overstated as a safe and non-invasive measure with clear evidence of an improvement in patients with obstructed defaecation and the potential to avoid surgery.

8. Irrigation

Transanal irrigation, first developed by Christensen et al., allows patients to better manage defecatory dysfunction with regular rectal irrigation and controlled bowel emptying. Its safety is well established, and randomised data has shown its efficacy in neurogenic bowel dysfunction and low anterior resection syndrome [51, 52, 53, 54, 55]. In obstructed defecation, there is no randomised data [56], but improvements in symptom severity and quality of life are well documented. Importantly, 50–60% of patients are no longer using the device after 12 months, indicating a significant dropout rate or potentially less efficacy or satisfaction [57, 58].

There is limited long-term data in obstructed defecation, and the therapy does require significant education, patient investment and time, but transanal irrigation clearly has a place in the treatment algorithm for obstructed defecation.

Antegrade colonic irrigation, something well recognised in children, has a role in the treatment of adult defecatory dysfunction although the data on results is limited. There are no comparative studies, but a systematic review in 2016 was able to analyse results in over 400 patients, 209 of whom had constipation, and found a 67.7% pooled success rate for constipated patients, at a median follow-up of 39 months. This included the Malone procedure, ileal neoappendicostomy, open caecostomy and percutaneous endoscopic caecostomy. There was a notably significant surgical morbidity [59]. For patients with intractable severe defecatory difficulties despite maximal treatment, antegrade colonic irrigation is something to be considered if transanal irrigation is not feasible or the patient chooses this over a colostomy.

9. Rectocoele repair

A rectocoele repair aims to address the impairment in biomechanics created by a rectocoele. A rectocoele is thought to form from traumatic detachment of the peri-cervical ring from the rectovaginal septum during labour [60]. Further pressure or straining can lead to herniation of the rectum and septum anteriorly, ultimately creating a pocket for stool and a loss of effective defecatory vector. Patients often are aware of a bulge and defecatory difficulties, and may even be aware of stool becoming trapped in the rectocoele.

The difficulty in the management of rectocoeles is in determining in which patients is the rectocoele the main player in the impaired defecatory mechanics. Successful surgery is only likely if the rectocoele is the main driver of symptoms.

Small (<2 cm) rectocoeles are a common finding, and 80% of parous females are diagnosed with a rectocoele on proctogram [61]. Over 30% of women with pelvic organ prolapse will have a rectocoele [62]; the difficulty is not in identifying a rectocoele, but in determining its significance. There is no universally accepted grading system for rectocoeles, with most measuring the maximal anterior extent of the rectocoele beyond the “normal” rectovaginal septum position. Gynaecological assessment assesses the extent of the rectocoele in relation to the vaginal introitus, the reference point for the POP-Q system. In general, only rectocoeles greater than 3 cm are considered potentially significant.

About 60% of rectocoeles occur in the setting of dyssynergia, and in these patients, initial treatment should be directed at the functional element with the usual strategy of supportive therapy and biofeedback. The excessive straining and impaired defecation from dyssynergia may well have accelerated the development of the rectocoele, and two case series have demonstrated worse surgical outcomes for rectocoele repair in patients with dyssynergia [63, 64].

The formation of a rectocoele represents a loss of suspensory ligamentous support and rarely occurs in isolation. A degree of internal rectal prolapse will be present in 80%, and some may also have symptomatic vaginal prolapse. The decision between rectocoele repair and rectopexy to address the internal rectal prolapse component is contentious and often based on the grade and anatomy of the internal rectal prolapse. In one series, rectal intussusception was predictive of a poorer result to the anterior Delormes operation [64].

In general, transanal rectocoele repair is more likely to be successful in patients who vaginally digitate, with a New Zealand study showing an 80% success for this group, who were the most likely to benefit from the surgery in their cohort [64]. The other factor is the rectocoele, which does not empty on proctography [65], although other papers have not shown any correlation between success and rectocoele size or contrast trapping [66].

Transanal repair includes a plication of the defective rectal muscularis layer, as well as excision of redundant mucosa. It is termed a Delormes operation in some parts of the world, and can be performed circumferentially, isolated to the anterior rectal wall where the rectocoele is, or tailored to the prolapse. It is very well tolerated, with minimal morbidity, and good outcomes at short-term follow-up. Over time, recurrence of the rectocoele may occur with some studies reporting recurrence rates approaching 50% by 5 years [64, 67]. In terms of functional results, long-term follow-up studies have demonstrated persisting benefits at 5 years, with sustained significant reductions in the Constipation Scoring System, Obstructed Defecation Score and Patient Assessment of Constipation Quality of Life scores [68, 69]. A persisting symptom improvement is more likely in patients who receive postoperative pelvic floor physiotherapy, and these patients are more likely to be satisfied [69]. There are concerns about potential worsening of faecal incontinence due to the anal stretch required for the procedure, although this is controversial. Some studies report up to 1/3 of previously continent women suffering gas or liquid incontinence at 5 years [67], but other more recent papers report a long-term improvement in faecal incontinence, with a 50% reduction in the Faecal Incontinence Severity Index in 2/3 of patients [68].

Transvaginal repair is usually performed by the gynaecologist and now includes a defect-specific repair of the damaged rectovaginal septum, perhaps better addressing the pathophysiology of the rectocoele. It results in significant improvement in obstructed defecation symptoms, including a reduced odds ratio of postoperative straining and incomplete emptying of 0.17 and 0.1 specifically [70]. Predictors of failure include residual rectocoele postoperatively, a higher preoperative Wexner score [71], shorter functional anal canal length and seepage on proctography [72]. There is, however, a high rate of sexual dysfunction [73]. Long-term results demonstrate a persisting benefit at 5 years, with a national register-based cohort study using patient reported outcome measures reporting over 70% ‘cure’ and over 75% satisfaction with the surgery [74].

Transperineal rectocele repair involves a curvilinear incision between the anal verge and posterior fourchette, and a dissection in the rectovaginal plane to allow its direct repair. Concomitant levatorplasty to restore the vaginal hiatus, and a sphincter repair if needed, can also be performed via this approach, along with a perineorrhaphy. Mesh or other implants have been used. There are only a small number of studies in the literature, reporting a median 72.7% improvement in symptoms and improvement in quality of life [75], but no long-term data is available.

A pelvic floor multidisciplinary team (MDT) meeting may assist in decision making as to the best surgical approach for each patient. A British team reported their experience with a pelvic floor MDT, with all 7 of their cases of prolapse and obstructed defecation having a change in management team [76].

In 2017, Grossi et al. published a systematic review encompassing an extensive literature review including transanal, trans-vaginal and trans-perineal approaches to rectocoele. This concluded with an overall low level of evidence and an inability to sufficiently compare procedures [77].

10. Stapled transanal procedures

Stapled transanal procedures for obstructed defecation followed Longo’s development of the technique in 2004 [78], with the concept of excision of the internally prolapsing rectum and redundant wall of the rectocoele leading to an improvement in anatomical derangement and thereby function. The procedure involves excision of rectal wall and creation of a stapled anastomosis. The STARR procedure involves separate excisions of the anterior and posterior prolapsing rectum, and the subsequent Trans-STARR procedure allows a more tailored excision of the prolapse using a Contour Transtar stapler. Specific exclusion criteria include an enterocoele at rest and anal incontinence with Wexner score > 7 [79]. Of 47 papers in a 2018 systematic review, all reported an improvement in constipation symptoms when recorded, with >50% improvement in ODS score, along with high rates of patient satisfaction [80]. No conclusions were able to be made regarding superiority of STARR vs. Trans-STARR.

In terms of safety, the systematic review by Mercer-Jones analysed the results of 8340 patients from multiple studies, with acceptably low morbidity. Postoperative bleeding occurred in 1.6%, sepsis in 0.2%, and anastomotic dehiscence in 0.3%, with very low rates of other serious complications. Postoperative pain was variably reported, but had an overall rate of 0.7% beyond 6 months. Urgency, often cited as a concern for the STARR procedure, was reported in 5.2% although how much of this was truly new urgency was debateable [80].

A more recent study of long-term outcomes out to 10 years, however, was somewhat concerning, with persisting pain and a significant rate of urgency reported as featured in the European STARR registry [81] and the 2010 NICE recommendation [82]. Amongst 60 patients at 10 years follow-up after STARR surgery, 38% had persisting perineal pain, 22% had urgency and 21% would not select STARR again [83].

11. Botulinum toxin injection for obstructed defecation

Dyssnergic defecation, now a recognised functional gastrointestinal disorder, can cause significant suffering, including symptoms of incomplete evacuation and straining as well as urgency and abdominal symptoms. Biofeedback, laxatives and improving toileting habits and lifestyle are standard basic treatment, usually beneficial in 70% of cases. Botulinum toxin-A targeted at specific hypertonic or non-relaxing muscles can improve symptoms when standard initial treatments fail [84]. Disordered defecation may respond to denervation of dysfunctional muscles, and biofeedback may be rendered more effective through a less paradoxical or less functionally obstructed defecation. Whilst the effect is temporary, the 2–3 month effect is an opportunity to take advantage of the alteration in defecatory manoeuvre and reinstitute a more physiologically “normal” coordination of the defecatory reflex [85, 86].

Subjective improvement has been reported in 30–100% with a reduction in the Constipation Severity Score [87, 88, 89], although the approach to injection and dosing is highly variable across institutions [85]. Dosages range from 12 to 200 units, with most studies targeting both puborectalis and the anal sphincter muscle. Techniques including palpation and ultrasound or electromyographic guidance, and the majority of procedures are performed either without anaesthesia or with sedation.

Serious complications are rare [90], with aggregated rates of faecal incontinence of 6.9% and flatal incontinence of 4.1% [85]. Not surprisingly, the finding of high-grade internal rectal prolapse may render Botulinum toxin less effective [91].

12. Rectopexy for obstructed defecation

Rectopexy for functional anorectal symptoms is centred around the premise of treating high-grade rectal intussusception and its effect on anorectal biomechanics, leading to an improvement in symptoms of obstructed defecation, quality of life and the often coexisting faecal leakage. In general, the main indication is high-grade internal rectal prolapse, with the rectopexy aiming to prevent the intussuscipiens from “plugging” the anal canal or activating the rectoanal inhibitory reflex. The rectocoele is also considered “treated” with better rectal wall support and creation of scar in the rectovaginal septum.

Traditionally used to treat external rectal prolapse, rectopexy has undergone many iterations over time, including the traditional posterior sutured rectopexy, resection rectopexy and the widely used ventral mesh rectopexy. Ventral mesh rectopexy, originally described by Andre d’Hoore, has the advantage of sparing the posterolateral dissection of the rectum—complete circumferential rectal mobilisation is thought to be responsible for the rates of de novo constipation reported, via division of lateral rectal ligaments and accompanying autonomic nerves [92].

Unfortunately, the evidence base for rectopexy for internal rectal prolapse and obstructed defecation remains low level, with only retrospective series published with varying quality and measurement of results. There are four papers on resection rectopexy, the most recent published in 2006, and multiple case series on ventral mesh rectopexy. With a lack of comparative papers, any conclusions regarding superiority between the surgical techniques have not been able to be confidently made [93]. Serious complications were rare, with Grossi’s systematic review suggesting a trend to a higher rate of surgical complications with resection rectopexy, although another systematic review by Emile et al. did not find difference [23]. Concerns regarding the use of mesh for functional GI disorders were addressed by the European Society of Coloproctology (ESCP) who published a guidance paper following rigorous literature review [94]. Mesh-related complications are serious but uncommon, reported in 1.1% of ventral mesh rectopexies for internal rectal prolapse [23]. The ESCP guidance document recommended mesh rectopexy be considered in the management of internal rectal prolapse, rectocoele and enterocoele, when conservative management is maximised and the condition continues to have a strong negative impact on quality of life.

In the medium term, 68% of patients report a subjective improvement in symptoms at a median of 44 months [95], and this corresponds to a significant improvement in symptom severity scores, with a significant drop in ODS scores sustained at 2 years [96]. Ventral mesh rectopexy is shown to improve constipation in 76.6%, with resection rectopexy improving 68.6% of patients. Concomitantly, and importantly, faecal incontinence symptoms improved in 62.5 and 52.7%, respectively [23].

Solitary rectal ulcer syndrome may be treated with ventral mesh rectopexy, with successful healing in 78% of patients [93].

Anatomical recurrence occurs in 2–7% of patients [93] and although this correlates with outcome, symptomatic recurrence is more relevant to patients and the true outcome in terms of function for this surgery will be borne out with longer-term follow-up and improved patient-reported outcome measures.

13. Conclusions

Obstructed defecation is a common, disabling condition with significant symptom crossover to other functional GI disorders as well as other pelvic floor problems. It requires a broad assessment as it involves functional, behavioural, psychological and anatomical aspects. Treatment is aimed at improving symptoms and quality of life and patients benefit from a multidisciplinary approach aiming to address all aspects of the dysfunction.

Supportive treatment and biofeedback therapy are a mainstay of patient management, with biofeedback also potentially improving the satisfaction and outcomes of any surgery. Surgery, in carefully selected cases after exhaustion of nonoperative treatment, is generally safe and carries good results although we still lack adequate data in the literature on important patient-reported outcomes, particularly in the longer term.