Internal Rectal Prolapse / Rectal Intussusception

David Jayne

Powerpoint File

Internal rectal prolapse or intussusception involves the full-thickness invagination of the lower rectum during the act of defaecation. The intussusception may extend down to or even into the anal canal, but protrusion beyond the anal verge is generally considered to be complete rectal prolapse and has traditionally been considered as a separate entity.

Internal rectal prolapse may exist as an incidental finding, usually in multiparous women, and when defaecatory symptoms exist it may be difficult to distinguish whether they are attributable to the prolapse or whether the prolapse is just coexistent. Internal intussusception as a feature of obstructed defaecation has been recognised for many years, but its central role in the pathophysiology of this condition has only recently been appreciated. Obstructed defaecation syndrome (ODS) is characterised by the normal urge to defaecate but an impaired ability to evacuate the rectum, and typically presents with features of excessive straining, laxative/enema dependence, incomplete and fragmented defaecation, and the need for perineal support or digitation to initiate evacuation. In ODS, the rectal intussusception is frequently accompanied by other structural abnormalities of the distal rectum, namely anterior rectocele and mucosal prolapse. However, it is the intussusception which is believed to be the central causative abnormality, as it descends with straining to “plug” the anal canal and prevent rectal evacuation. Rectal intussusception may also present with symptoms of faecal incontinence, particularly in multiparous females with co-existent anal sphincter dysfunction. It has also been implicated in the Solitary Rectal Ulcer Syndrome (SRUS), with recurrent prolapse leading to traumatic ulceration and symptoms of bleeding and rectal pain. It is important to appreciate that rectal intussusception is frequently a manifestation of a more generalised pelvic floor weakness, and in up to 40% of cases is associated with other urogential prolapse.

Although the diagnosis of rectal intussusception may be made on proctoscopy with straining, it is more readily appreciated by defaecating proctography. Typically an invagination of the distal rectum is observed during straining, producing a funnelling effect with shelf-like infolding of the rectal wall. Several classifications have been proposed in an attempt to quantify the extent of prolapse and correlate it to symptomatology. These include the system proposed by Wexner (1), which subdivides intussusception into 1st degree (<10mm infolding on the rectal wall) and 2nd degree (>10mm infolding extending into the anal canal). Anorectal physiology studies may reveal an increased rectal capacity, low compliance, and elevated threshold and maximum tolerated sensory levels. A co-existent pundendal neuropathy may be present. Endoanal ultrasound is of benefit in excluding an occult sphincter defect prior to considering surgical intervention.

Conservative treatment regimens have been advocated and attempt to produce symptomatic relief of obstructed defaecation by dietary manipulation combined with the use of laxatives and enemas. Rectal irrigation systems may be of some benefit as may biofeedback therapy, although the long-term benefits of biofeedback therapy are only seen in approximately 50% of patients. Surgical options have traditionally included the internal Delorme’s procedure, rectopexy, and low anterior resection. The internal Delorme’s procedure has been reported to achieve reasonable success rates of 70% for relief of obstructed defaecation symptoms (2-4). Although it is a well-tolerated, low morbidity option, it can however be technically challenging. Rectopexy has been associated with poor results and is generally not recommended (5). Similarly, the high morbidity and unpredictable functional outcomes associated with low anterior resection make it an unattractive option.

Recently, the treatment of rectal intussusception and obstructed defaecation has been transformed with the introduction of the Stapled Transanal Rectal Resection (STARR) procedure (6). Developed by Antonio Longo as an extension of the stapled haemorrhoidopexy, the STARR procedure aims to produce a full-thickness circumferential resection of the distal 5-6cm of rectum, incorporating the intussusception together with any accompanying rectocele or mucosal prolapse. The structurally deficient lower resection is excised and a shorter, less capacious neorectum is created.

To date there have been 4 studies reporting the efficacy and safety of STARR in the treatment of ODS (7-10). All involve small patient numbers, with the largest recruiting 90 patients in a multicentre, prospective study. Outcomes are limited to the short-term with the longest follow-up being 20 months. Despite the shortcomings of these studies, the results offer guarded optimise with short-term efficacy rates in the region of 80%. The procedure appears to be associated with a low morbidity with the most frequently reported postoperative complications being bleeding, urinary retention, and pain. Postoperative incontinence does not appear to be a problem, with a subgroup of patients reporting symptomatic improvement. Defaecatory urgency is more commonly encountered in 20-30% of patients but in the most cases appears to be a transient phenomenon, resolving by 3 months postoperatively.

In an attempt to better understand the issues involved in STARR/ODS a prospective STARR UK Registry is being run under the auspices of the Association of Coloproctology of GB&I. To date, information on over 100 STARR/ODS patients has been collected and the initial data analysis will be presented at the forthcoming ACPGB&I annual meeting in July 2007.

REFERENCES
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