There are many excellent reviews of the surgical treatment of rectal prolapse, but there are few that have specifically addressed the issue of constipation in rectal prolapse patients.
It is worth remembering that almost every patient with a rectal prolapse has some abnormality of bowel function. Whether the abnormality of bowel function is the cause of the prolapse or whether the functional bowel abnormality is a consequence of the prolapse is difficult to say.
Constipation in Rectal Prolapse
Rectal prolapse is considered by most authorities to be a true intussusception of the rectum through the pelvic floor and sphincters. Video-proctographic studies clearly demonstrate the apex of a rectal prolapse descending through the ampulla of the rectum and through the puborectalis swing to appear inside the anal canal and subsequently on the perineum as a rectal prolapse.
It is unknown whether an intussusception subsequently develops into a full-thickness rectal prolapse. Studies on the long-term natural history of intussusception indicate that some patients do ultimately develop full-thickness rectal prolapse.
Intussusception is commonly associated with chronic straining due to a feeling of incomplete evacuation of the rectum, causing straining and in time possibly the development of a full-thickness rectal prolapse.
There is no doubt that intussusception is commonly associated with obstructed defecation, purely on the basis of mechanics. Thus, the intussusception fills the lumen ofthe rectum and prevents normal evacuation. It is quite likely that there are some patients who have a primary problem of colonic inertia and impaired rectal emptying who, as a result of straining, develop an incomplete intussusception, which exacerbates the constipation. Hence, it is likely that a small proportion of patients with rectal prolapse have a primary abnormality of colonic transit and rectal emptying, leading to an intussusception, which subsequently forms into a full-thickness rectal prolapse.
Schultz and colleagues compared the results of Marlex rectopexy in 46 patients with a full-thickness rectal prolapse to 29 with an intussusception. A much higher proportion of patients with intussusception developed deteriorating constipation compared with the prolaspe group.
A careful history in patients with rectal prolapse indicates that between 30% and 45% of women suffering from full-thickness rectal prolapse have constipation. Often there is a history of incomplete rectal evacuation. It is more common, however, to elicit a history of fecal incontinence in patients with rectal prolapse, as approximately 70% of women with a full-thickness rectal prolapse suffer bowel incontinence, with urgency, imperfect control of flatus, soiling, and poor bowel control, particularly if there is associated straining.
Investigation in Rectal Prolapse Patients
Investigation in patients who have full-thickness rectal prolapse can be notoriously difficult. Colonic transit marker studies may be performed to assess the presence of colonic inertia, but they should probably be repeated, as a single study may be unreliable. Between 30% and 50% of women with full-thickness rectal prolapse have associated impaired colonic transit ; this incidence may be even higher in men.
Videoproctography is remarkably difficult to interpret in patients with rectal prolapse. There is nearly always an intussusception, and a full-thickness rectal prolapse can usually be demonstrated. The presence of the intussusception or the prolapse may mask underlying impaired rectal evacuation. Thus, interpretation of videoproctography as a means of identifying the proportion of prolapse patients who also have impaired rectal emptying may be difficult.
A good clinical history is probably the most important single investigation. Patients will tell you whether or not they have to strain to evacuate. Patients will also be able to identify if they have infrequent evacuation with relatively normal emptying. If a patient has a history of chronic laxative use with difficulty evacuating, concomitant colectomy may be seriously considered. In patients with laxative dependence, constipation is often worsened following abdominal rectopexy Thus, if colonic inertia is identified, a subtotal colectomy with ileoproctostomy may be indicated. Similarly, finding a symptomatic third-degree sigmoidocele with otherwise normal colonic transit may warrant a synchronous sigmoid colectomy.
A word of warning is needed with respect to resection rectopexy. Fixation of the prolapse and coexisting resection of the sigmoid may control the prolapse and normalize constipation, but if an excessively long left-sided colonic resection is performed, there may be a risk of precipitating incontinence. Most rectal prolapse patients have a patulous anus associated with low resting and squeeze pressures. There is a fine line between postoperative continence with some constipation and incontinence but control of the prolapse with elimination of constipation. Thus, resection rectopexy should be reserved for patients with a clear history of preoperative constipation where there have been no factors that may have weakened the sphincter. Moreover, clinical examination, anal manometry, and anal ultrasonography should all reveal satisfactory findings.
Thus, the thrust of preoperative investigations in rectal prolapse patients is not only to determine colonic transit and impaired rectal evacuation, but also to assess whether the sphincters are strong enough to withstand the consequences of a colonic resection. Although this is an important warning note, the data seemed to indicate that resection rectopexy has no deleterious effect on either resting or squeeze anal canal pressure compared with rectopexy alone. Furthermore, the incidence of persistent incontinence is no greater after resection rectopexy compared with resection rectopexy alone. In fact, the incidence of postoperative constipation is superior after resection rectopexy as compared to rectopexy alone. Two prospective randomized studies revealed superior function after resection rectopexy as compared to rectopexy alone. Specifically, Luukkonen and coworkers prospectively randomized 30 patients between abdominal rectopexy and sigmoid resection versus rectopexy alone. While constipation disappeared in three patients after resection rectopexy and in two other patients after rectopexy alone, it became considerably worse in five additional patients who had rectopexy alone, one of whom required a colectomy. The authors noted that although surgery did not significantly change colonic transit times and did seem to increase operative morbidity, sigmoid colectomy did diminish postoperative constipation specifically, causing less obstruction.
In a similar study, McKee and associates prospectively randomized 18 patients with full-thickness rectal prolapse to rectopexy with or without sigmoid colectomy. Using postoperative colonic transit studies, the authors noted that after rectopexy alone there was a statistically significantly higher number of patients who developed postoperative marker delay as compared to patients after sigmoid colectomy with rectopexy. Anorectal physiologic investigation may have helped provide some answers to this difference, in that patients following rectopexy alone had a significantly higher rectal compliance than did patients after resection rectopexy. The authors have hypothesized that the redundant sigmoid colon may have delayed passage of the intestinal contents and caused kinking at the junction of the sigmoid and rectum.
Risk Factors for Constipation
The principal risk factor for constipation after rectopexy for rectal prolapse is young age. Young patients have a high rate of recurrence, and the majority have been constipated for most of their lives. In the majority of these young people rectal prolapse is secondary to a long history of chronic straining.
Thus, young people with a rectal prolapse should be thoroughly investigated. In this group, not only should there be an assessment of colonic transit, but it would be wise to assess small-bowel transit and even gastric emptying as well, as some of these patients have a panenteric myopathy or neuropathy. These are a group of patients in whom electromyography (EMG) assessment of puborectalis activity during straining might identify patients with anismus in whom results are likely to be poor. Panenteric inertia may preclude any resection and pelvic outlet obstruction may be amenable to biofeed-back or botulinum toxin injection.
Other risk factors for postoperative constipation are (1) patients with gross perineal descent, (2) patients who admit to a history of straining, and (3) patients with a coexisting solitary rectal ulcer.
Advice Regarding Primary Treatment for Prolapse in Patients with a History of Constipation or Impaired Evacuation Without Colonic Inertia or Megacolon
Resection rectopexy may be strongly recommended in most of these patients. All the evidence points to the fact that resection rectopexy has a lower incidence of postoperative constipation compared with rectopexy alone.
The literature suggests that the rectopexy should be sutured and that a foreign material should be avoided. The incidence of constipation is much higher if Marlex or Ivalon or other foreign materials are used for fixation of the rectum.
Anterior rectopexy (Ripstein procedure) would also be contraindicated in patients with a history of constipation. The incidence of constipation after anterior rectopexy, even without stenosis, is very high, and there is a risk of mechanical stricturing as well.
A randomized controlled trial comparing Ivalon rectopexy with sutured rectopexy reported a lower incidence of constipation when the foreign body was avoided.
Perhaps the most difficult question to answer is how much colon to remove. Usually in resection rectopexy the sigmoid is removed so that the large bowel is straight between the descending colon and the rectum, with some bowstring-ing as a consequence of the rectopexy. Some data would support a subtotal colectomy in a patient with colonic inertia where anal sphincter anatomy and function are satisfactory and where there is no history of incontinence.
Constipation After Rectopexy in Patients Who Have Had No Apparent Constipation Beforehand
The other major consideration in rectal prolapse surgery is the risk of rendering patients constipated after the operation.
Factors that seem to increase the risk of constipation for the first time after rectopexy are age under 40, the use of mesh, anterior rectopexy, avoidance of resection, and the use of an open operation as opposed to laparoscopic rectopexy and division of the lateral stalks.
The problem with postoperative constipation after rectopexy is that it is very difficult to predict who will become constipated and thus in whom concomitant resection would be justified.
To help avoid disappointed patients, it is crucially important to warn patients that rectopexy might conceivably precipitate or exacerbate constipation. Similarly, they should have these same expectations about new or preexisting fecal incontinence.
All the evidence suggests that open rectopexy, particularly with mesh, has a 20% to 40% risk of causing constipation. Recent data suggest that the incidence of constipation is probably reduced by laparoscopic rectopexy, even without a resection, and that the number who develop constipation for the first time is also small.
Warning About Risk
The key messages are that patients having a rectopexy, even if they do not suffer from any pre-operative constipation, should be warned about the risks of postoperative constipation. Furthermore, the majority of these patients should be offered a resection rectopexy on the grounds that this does not in any way increase the risk of incontinence while reducing the incidence of postoperative constipation. Division of the lateral stalks will reduce the incidence of postoperative recurrence at the expense of increasing the incidence of postoperative constipation. A prospective randomized study was undertaken including 26 patients with full-thickness rectal prolapse. Fourteen patients had rectopexy with and 12 without division of the lateral ligaments. Incontinence improved in both groups of patients; however, the authors note that division of the lateral ligaments statistically significantly increased the number of patient with postoperative constipation. While three patients had preoperative constipation, 10 patients suffered postoperative constipation in this latter group. Although mean anal canal pressures were higher after surgery in all patients in the study, sensory thresholds significantly increased in those in whom the ligaments had been divided but not in those in whom they had been preserved. However, these benefits of preservation of the lateral stalk were at the expense of an increased rate of recurrence, as prolapse recurred in six patients in whom the stalks were not divided, but did not recur in any of the 12 patients in whom the ligaments were divided. Therefore, there seems to be a balance between improved function but a worsened outcome relative to recurrence when the ligaments were divided. Conversely, there was a low rate of recurrence, although at the expense of a higher rate of constipation when the ligaments are divided. Surgeons should consider these variables and discuss them with the patient prior to surgery for rectal prolapse.
To date, the results of laparoscopic rectopexy and resection rectopexy seem to be associated with less constipation than open rectopexy alone. Thus, laparoscopic treatment should be encouraged, provided the recurrence rates remain low.
All patients who develop postoperative constipation should be investigated by colonic transit studies and probably also by small-bowel transit studies, videoproctography, and anal manometry and contrast enema. These studies should help identify both physiologic and anatomic causes of constipation.
If the original operation was rectopexy alone, then subsequent sigmoid resection might be contemplated as a secondary procedure. Conversely, sigmoid colectomy alone is unlikely to resolve the problems of persistent constipation, and a high proportion of these individuals require a subtotal colectomy and ileorectal anastomosis. Thus, the majority of patients with constipation after a previous rectopexy, after appropriate counseling and investigation, are likely to be offered some form of subtotal colectomy, provided that their sphincter anatomy and function are satisfactory and provided that the preoperative tests do not indicate a high risk of incontinence.