Defecography
Defecography is a dynamic fluoroscopic study performed in the sitting position after injecting 150 mL of barium paste into the patient’s rectum. Defecography provides useful information about structural changes (e.g., rectoceles, enteroceles, rectal prolapse, and intussusception), DD, and descending perineum syndrome.38 Methodological differences, radiation exposure, and poor interobserver agreement have limited its wider use; therefore, anorectal manometry and the balloon expulsion test are recommended for the initial evaluation of DD.39 Magnetic resonance defecography may be more useful.17,38
Colonic transit studies
Colonic transit study can be assessed using radiopaque markers, wireless motility capsule, or scintigraphy. Wireless motility capsule and scintigraphy have the advantage of determining gastric, small bowel, and whole gut transit times as well. About two-thirds of patients with DD have slow transit constipation (STC),6 which improves after treatment of DD.40 Hence, in patients with chronic constipation, evaluation and management of DD is recommended first. If symptoms persist, then consider colonic transit assessment.41 Given the overlapping nature of the conditions, documentation of STC at the outset could facilitate treatment of both.
Diagnostic criteria for DD
Patients should fulfill the following criteria for diagnosis of DD:42,43
- Fulfill symptom(s) diagnostic criteria for functional constipation and/or constipation-predominant IBS.
- Demonstrate dyssynergic pattern (Types I-IV; Figure) during attempted defecation on manometry recordings.
- Meet one or more of the following criteria:
- Inability to expel an artificial stool (50 mL water-filled balloon) within 1 minute.
- Inability to evacuate or retention of 50% or more of barium during defecography. (Some institutions use a prolonged colonic transit time: greater than 5 markers or 20% or higher marker retention on a plain abdominal x-Ray at 120 hours after ingestion of one radio-opaque marker capsule containing 24 radio-opaque markers.)
Treatment of DD
The treatment modalities for DD depend on several factors: patient’s age, comorbidities, underlying pathophysiology, and patient expectations. Treatment options include standard management of constipation, but biofeedback therapy is the mainstay.
Standard management
Medications that cause or worsen constipation should be avoided. The patient should consume adequate fluid and exercise regularly. Patients should receive instructions for timed toilet training (twice daily, 30 minutes after meals). Patients should push at about 50%-70% of their ability for no longer than 5 minutes and avoid postponing defecation or use of digital maneuvers to facilitate defecation.42 The patients should take 25 g of soluble fiber (e.g., psyllium) daily. Of note, the benefits of fiber can take days to weeks44 and may be limited in patients with STC and DD.45 Medications including laxatives and intestinal secretagogues (lubiprostone, linaclotide, plecanatide), and enterokinetic agents (prucalopride) can be used as adjunct therapy for management of DD.42 Their use is titrated during and after biofeedback therapy and may decrease after successful treatment.46
Biofeedback therapy
Biofeedback therapy involves operant conditioning techniques using either a solid state anorectal manometry system, electromyography, simulated balloon, or home biofeedback training devices.42,47 The goals of biofeedback therapy are to correct the abdominal pelvic muscle discoordination during defecation and improve rectal sensation to stool if impaired. Biofeedback therapy involves patient education and active training (typically six sessions, 1-2 weeks apart, with each about 30-60 minutes long), followed by a reinforcement stage (three sessions at 3, 6, and 12 months), though there are variations in training protocols.42
Table
The success of biofeedback therapy depends on the patient’s motivation and the therapist’s skills.42 Compared with standard therapy (diet, exercise, pharmacotherapy), biofeedback therapy provides sustained improvement of bowel symptoms and anorectal function. Up to 70%-80% of DD patients show significant improvement of symptoms in randomized controlled trials (Table).48-52 Biofeedback therapy may also improve dyspeptic symptoms.53 Patients with harder stool consistency, greater willingness to participate, lower baseline bowel satisfaction, lower baseline anal sphincter relaxation, and prolonged balloon expulsion time, as well as patients who used digital maneuvers for defection, more commonly respond to biofeedback therapy.54,55 Longstanding laxative use has been associated with decreased response to biofeedback therapy.56 In patients with rectal hyposensitivity, barostat-assisted sensory training is more effective than a hand-held syringe technique.30 In patients with constipation predominant IBS and rectal hyposensitivity, sensory adaption training is more efficacious and better tolerated than escitalopram.30 Biofeedback therapy was afforded a grade A recommendation for treatment of DD by the American and European Societies of Neurogastroenterology and Motility.57
The access to office-based biofeedback therapy may be limited because of costs and low availability. The time required to attend multiple sessions may be burdensome for some patients, especially if they are taking time off from work. A recent study showed that patients with higher level of education may be less likely to adhere to biofeedback therapy.58 Recently, home biofeedback was shown to be noninferior to office biofeedback and was more cost-effective, which provides an alternative option for treating more patients.59
Endoscopic/surgical options
Other less effective treatment options for DD include botulinum toxin injection and myectomy.60-62 Botulinum toxin injection appears to have mixed effects with less than 50% of patients reporting symptomatic improvement, and it may cause fecal incontinence.60,63
Conclusion
DD is a common yet poorly recognized cause of constipation. Its clinical presentation overlaps with other lower-GI disorders. Its diagnosis requires detailed history, digital rectal examination, prospective stool diaries, anorectal manometry, and balloon expulsion tests. Biofeedback therapy offers excellent and sustained symptomatic improvement; however, access to office-based biofeedback is limited, and there is an urgent need for home-based biofeedback therapy programs.59
Dr. Rao is J. Harold Harrison Distinguished University Chair, professor of medicine, director of neurogastroenterology/motility, and director of digestive health at the Digestive Health Clinical Research Center Augusta (Georgia) University. He is supported by National Institutes of Health grants R01DK121003-02 and U01DK115572. Dr. Jehangir is a gastroenterology and Hepatology Fellow at the Digestive Health Clinical Research Center at Augusta University. They reported having no conflicts of interest.
