Constipation is not only a clinical disease but also one of the most common gastrointestinal symptoms. It is characterized by dry, hard stool that is difficult to pass and a significantly prolonged duration of defecation. The prevalence of chronic constipation in the general population is approximately 4% to 6%, with a gender ratio of 1:3 (male to female). Its incidence increases with age.
Etiology and Classification
The causes of constipation are highly complex. Various gastrointestinal disorders, abnormalities of the neuroendocrine or metabolic systems, and certain specific medications can result in chronic constipation. It may be caused by impaired colonic function (including digestive and absorption disorders or dysmotility) or by anorectal outlet obstruction, including dysfunction of the sphincters. In addition, proctology classifies cases requiring specialized clinical management into colonic slow transit constipation (STC) and outlet obstructive constipation (OOC). When both mechanisms are present, the condition is referred to as mixed constipation. Common conditions leading to outlet obstructive constipation include rectocele, rectal mucosal prolapse, puborectalis syndrome, and pelvic floor spasm syndrome.
This discussion focuses on chronic constipation requiring surgical intervention, with a primary emphasis on STC, OOC, and mixed constipation.
Diagnosis
Colonic Slow Transit Constipation
STC is caused by reduced transit speed in the colon and frequently occurs in elderly individuals and young women. Patients exhibit infrequent bowel movements, with intervals of 2–3 days or longer. Symptoms often include abdominal distension and discomfort. Colonic transit time testing may reveal either generalized slow transit throughout the entire colon or delayed segmental colonic transit.
Rectocele
Rectocele is more common in women and results from weakening of the rectovaginal septum or a descending perineum. Chronic straining during defecation causes the rectum to bulge toward the vaginal side, leading to difficulty with stool evacuation. This condition is characterized by difficulty in defecation, which may necessitate manual assistance. Patients may report using their thumb to apply pressure from the vaginal side to aid in stool passage. Rectal examination and defecography can confirm the diagnosis, with defecography demonstrating the width and depth of the rectocele.
Rectal Mucosal Internal Prolapse
Internal prolapse of the rectal mucosa occurs due to mucosal laxity. During defecation, the mucosa folds in on itself, causing intussusception and obstruction at the upper anal canal, leading to difficulty with evacuation. The greater the straining, the worse the obstruction. Defecography may show a funnel-shaped image or layered intussusception of the mucosa on lateral rectal views during straining. Digital rectal examination may reveal lax mucosa or accumulation of mucosal tissue within the rectal cavity.
Puborectalis Syndrome
Spasm, hypertrophy, or fibrosis of the puborectalis muscle results in difficulty relaxing the muscle during defecation, causing outlet obstruction and constipation. This condition is characterized by progressive, chronic, and severe difficulty with defecation. Digital rectal examination may demonstrate increased tension in the anal canal, while anal manometry may show elevated resting and squeeze pressures. Electromyography of the puborectalis muscle and external sphincter may reveal abnormal electrical activity. Colonic transit studies commonly show marked rectal retention, and defecography can identify hypertrophy or a "shelving" appearance of the puborectalis muscle.
Pelvic Floor Spasm Syndrome
Normal defecation requires relaxation of both the puborectalis muscle and the external anal sphincter, which increases the anorectal angle and relaxes the anal canal, allowing for smooth stool passage. If these muscles fail to relax or contract paradoxically during defecation, outlet obstruction occurs, leading to constipation. Digital rectal examination may reveal significant increases in anal canal tension. Anal manometry often shows elevated resting pressure, while defecography indicates that the anorectal angle fails to widen or even narrows during straining.
Treatment
Non-Surgical Treatment
Non-surgical treatment is recommended as the initial approach for chronic constipation. This includes dietary changes favoring foods rich in dietary fiber and establishing healthy bowel habits. When necessary, laxatives, suppositories, or enemas may be used as adjunct therapies. Biofeedback therapy shows some efficacy across different types of constipation. When non-surgical treatments prove ineffective, and there is a clear anatomical abnormality or surgical indication, as long as contraindications to surgery are excluded, surgical intervention may be considered.
Surgical Treatment
Surgical treatment primarily addresses two types of defects in stool transit and evacuation: outlet obstruction and slow transit through the colon. For outlet obstructive constipation, treatment targets the underlying causes, while for colonic slow transit constipation, the non-functioning portion of the colon may need to be resected. Since the two conditions may co-exist, careful consideration is required to determine an appropriate surgical plan.
Colonic Resection
Two main techniques are employed: total colectomy with ileorectal anastomosis, and subtotal colectomy with cecorectal anastomosis. These procedures are primarily used for colonic slow transit constipation and have demonstrated reliable outcomes.
Rectocele Repair
Rectocele repair is performed to treat rectocele-related constipation and includes two approaches: closed repair and open repair. Both aim to strengthen the weakened area of the rectovaginal septum. A commonly used technique in clinical practice is the transrectal open repair procedure, also known as the Sehapayak procedure. This involves a longitudinal incision in the anterior midline of the rectum above the dentate line, reaching the submucosal layer. After mobilization of the mucosal flaps to both sides, the edges of the levator ani muscles are sutured intermittently (3 to 5 stitches) to reinforce the rectovaginal septum. The mucosal incision is then closed with sutures.
Rectal Mucosal Resection
Partial rectal mucosal resection is performed either circumferentially or longitudinally using specialized hemorrhoid staplers or linear cutting staplers. This treatment aims to fix the rectal mucosa and has demonstrated some efficacy in managing rectocele and rectal mucosal prolapse.
Puborectalis Muscle Transection or Partial Resection
This procedure is used to treat puborectalis syndrome. After confirming the puborectalis muscle through a sacrococcygeal approach, surgical transection or gradual transection via a seton technique may be performed to address the issue.
Chronic constipation involves complex etiologies, and different causes require different treatment approaches. Surgery is effective in constipation with well-defined surgical causes. However, incomplete preoperative diagnostic evaluation is one of the reasons for postoperative recurrence of constipation or suboptimal surgical outcomes.