Dyssynergic Defecation

Dyssynergic defecation is a functional defecation disorder in which paradoxical contraction or inadequate relaxation of the pelvic floor and anal sphincter, or inadequate propulsive forces, impairs rectal evacuation.

• Accounts for about 25 to 50% of patients with chronic constipation referred to tertiary centres.
• Types (Rao): type I (adequate propulsion with paradoxical anal contraction), type II (inadequate propulsion with paradoxical contraction), type III (adequate propulsion with absent or incomplete sphincter relaxation), type IV (inadequate propulsion with absent or incomplete relaxation).
• Causes: learned behaviour, childhood toilet training, abuse, pelvic surgery, obstetric trauma, neurological disease (Parkinson, multiple sclerosis, spinal injury).
• Associated with rectocele, intussusception, solitary rectal ulcer, rectal hyposensitivity.
• Complications: faecal impaction, overflow incontinence, haemorrhoids, fissure, rectal prolapse.

• Straining, hard stool, sensation of incomplete evacuation, digital evacuation or perineal pressure to defecate, prolonged toilet time, abdominal bloating.
• Infrequent urge to defecate. May present with normal stool frequency.
• Rectal examination: paradoxical contraction of the puborectalis or anal sphincter on simulated defecation, increased tone, tenderness.
• Red flags: rectal bleeding, weight loss, anaemia, family history of colorectal cancer, change in bowel habit.

Requires at least two abnormal tests from the following

• Anorectal manometry with balloon expulsion test (inability to expel a 50 mL water filled balloon within 1 minute), dyssynergic patterns.
• High resolution anorectal manometry: rectoanal pressure gradient.
• Defecography (barium or MRI): impaired anal opening, prolonged evacuation, rectocele, intussusception, inadequate puborectalis relaxation.
• Colonic transit study (radiopaque markers or wireless capsule) to identify slow transit overlap.
• Colonoscopy per age and alarm features; endoanal ultrasound if incontinence.
• Exclude hypothyroidism, hypercalcaemia, diabetes, medications (opioids, anticholinergics).

• Biofeedback therapy: first line, 5 to 6 weekly 30 to 60 minute sessions, improving coordination of abdominal push with pelvic floor relaxation, success in 70 to 80%; home training devices extend benefit.
• Laxatives: psyllium 5 to 10 g twice daily, macrogol 17 to 34 g daily, bisacodyl 10 mg suppository for evacuation.
• Behavioural measures: toilet routine after meals, footstool for squatting posture, avoid prolonged straining.
• Botulinum toxin injection (50 to 100 units into the puborectalis) for refractory cases, short lived benefit.
• Treat structural disease: surgical correction of symptomatic rectocele or intussusception (ventral rectopexy) only after biofeedback fails.
• Prucalopride 2 mg daily for slow transit component; linaclotide 290 micrograms daily.
• Sacral neuromodulation in selected faecal incontinence overlap.
• Review at 3 months for symptom improvement and satisfaction.