At a glance
Obstructed defecation syndrome (ODS) describes a difficulty with the physical act of passing stool, despite having the urge and often despite having adequately soft stool. It is different from typical constipation, where the issue is infrequent or hard stools.
People with ODS describe straining excessively, spending a long time on the toilet, needing to use their fingers to assist evacuation, and feeling that their bowel movements are never complete. It is more common than many people realise, and it is treatable.
What causes it
ODS can result from one or more of these mechanisms:
Pelvic floor dysfunction
The muscles of the pelvic floor need to relax in a coordinated way to allow stool to pass. In ODS, this coordination may be impaired:
- Dyssynergic defecation — the pelvic floor muscles tighten instead of relaxing during attempted evacuation
- Hypertonic pelvic floor — chronically tense muscles that resist the relaxation needed for evacuation
- Weak pelvic floor — insufficient support for the structures involved in evacuation
Structural causes
- Internal rectal prolapse (intussusception) — the rectal wall folds inward during straining, blocking the passage
- Rectocele — a bulging of the rectal wall (commonly into the vaginal space in women) where stool can become trapped
- Enterocele — herniation of small bowel into the pelvic space, pressing on the rectum
- Descending perineum syndrome — excessive descent of the pelvic floor during straining
Combined factors
Many people with ODS have a combination of functional and structural factors. A person may have a small rectocele that becomes problematic only because their pelvic floor is also dyssynergic. Identifying all contributing factors is important for effective management.
Symptoms
People with ODS commonly describe:
- Excessive straining during bowel movements
- Spending a long time on the toilet with poor results
- A sensation of incomplete evacuation
- Needing to return to the toilet shortly after going
- Using fingers to assist evacuation (digitation)
- Needing to press on the vaginal wall or perineum to facilitate passage
- Pain or discomfort during bowel movements
- Frustration and reduced quality of life
How it is diagnosed
Clinical assessment
A thorough history and physical examination, including a rectal examination, is the starting point. A clinician experienced in pelvic floor disorders can often identify likely causes from the history alone.
Specialised tests
- Defecography — an imaging study performed while the person empties their bowel. It can identify structural causes like internal prolapse, rectocele, and descending perineum.
- Anorectal manometry — measures the pressures and coordination of the sphincter and pelvic floor during squeezing and attempted evacuation
- Balloon expulsion test — a simple test of the ability to expel a small balloon from the rectum, which can identify outlet obstruction
- Transit study — markers swallowed and tracked to determine whether slow transit is also present
Management
Conservative approaches (first line)
Pelvic floor physiotherapy is typically the first-line treatment and can be highly effective:
- Biofeedback — using sensors to show you in real time how your muscles are behaving, allowing you to retrain the coordination
- Relaxation techniques — learning to relax the pelvic floor consciously
- Correct defecation technique — posture, breathing, and avoiding straining
Dietary optimisation:
- Adequate fibre to ensure well-formed, soft stools
- Proper hydration
- Regular meal patterns to support predictable bowel function
Behavioural changes:
- Correct toilet posture — feet elevated, leaning forward slightly
- Time limits on toilet visits — five minutes maximum
- Not straining — if it is not coming, get up and try later
- Responding to the urge promptly rather than deferring
Surgical approaches (second line)
Surgery is considered when conservative measures have been fully explored and a clear structural cause has been identified:
- STARR procedure — for internal prolapse causing obstruction
- Rectocele repair — for significant rectocele contributing to trapping
- Rectopexy — for rectal prolapse
- Ventral mesh rectopexy — for combined prolapse and rectocele
Surgical outcomes depend heavily on proper patient selection and comprehensive pre-operative assessment.
Living with ODS
ODS is a chronic condition for many people, but it is manageable. People describe:
- The importance of finding a clinician who takes the condition seriously
- Pelvic floor physiotherapy as the intervention that made the biggest difference
- Dietary and behavioural changes that took time to become habits but eventually felt natural
- The emotional relief of having a diagnosis and understanding why evacuation was so difficult