Constipation

What is constipation? 

Constipation is a common digestive disorder broadly defined as unsatisfactory, infrequent passages of hard poo with difficulty. According to the Rome III criteria: 

1) At least 2 symptoms below must be present for at least 3 months

• < 3 bowel motions per week 

• Straining of stool at least 25% of defecation 

• Hard stools occurring at least 25% of the time 

• Sensation of anorectal obstruction at least 25% of defecations 

• Incomplete evacuation at least 25% of defecations 

• Digital evacuation at least 25% of defecations 

2) There should be no loose stools without laxatives

3) Exclusion of constipation predominant irritable bowel syndrome (IBS) 

Causes of constipation?

Majority is idiopathic (i.e. no obvious cause). Secondary causes include dietary, metabolic, endocrinology, neurological, psychiatric, behavioural, medication, pelvic surgery, sexual abuse, as well as obstructing lesions 

Evaluation of constipation failing simple lifestyle modification 

• Slow transit studies 

• Anorectal physiology 

• MRI defecography 

How is constipation treated?

Most constipation are treated in GP setting. Referral to a colorectal surgeon are usually made in cases refractory to simple lifestyle modifications or medical treatments 

Conservative measures 

Lifestyle modification 

• Increase fluid intake 

• Increase physical activity (avoid sedentary lifestyle)

• Regular toileting 

Medication options 

• Fibre / Bulking agents: Works by increasing the “bulk” which in turn stimulates your bowel. Consider starting with twice a day dosing. Taken with fluids and meals. Maximal effect can be seen after several weeks. 

  • Psyllium (partially soluble fibre)

  • Metamucil 

• Osmotic laxative: Works by drawing water from the rest of the body into your bowel to soften poo and make it easier to pass. 

  • Lactulose 

  • Macrogol (movicol) 

  • Polyethylene glycol (PEG)

• Stimulant laxatives: Works by stimulating the muscle that lines your bowel, helping to move poo along to the back passage. Taking stimulant laxatives 30 minutes after meal may synchronise its propulsive effect. It can be used as a rescue agent when you have not had a bowel action for > 2 days despite bulking agent or osmotic laxatives. 

  • Senna

  • Biscodyl

  • Sodium picosulfate 

• Stool softeners: Works by letting water in to soften poo + make it easier to pass 

  • Docusate 

• Biofeedback: Aims to restore normal physiology of defecation. It is the treatment of choice for dyssynergic defecation 

• Novel therapies e.g. Prucalopride: Peristalsis activation and coordination, resulting in colonic mass movements.