Constipation: Causes, Symptoms, and Treatment

• Constipation: ICD 10 Code = K59
• Case study involves Mrs Kemotho Mokabani, a 72-year-old female.
• Chief complaint includes the absence of bowel movement for one week.
• She was given morphine tablets for pain after knee replacement surgery
• Patient is not able to eat or drink much, and feels full with stomach cramps.
• She feels the need to go to the toilet but nothing comes out.
• Level of pain reported at 7 on a scale from 0 to 10
• Further information to collect includes: Mobility following surgery, medicines used for pain, medical conditions, medication being taken, social history including smoking/alcohol, diet, urine output, physical activity, adherence to prescribed medicine, laxative use.
• Constipation is defined by stool quantity, quality, frequency, size, consistency, with difficulty or less frequent passage.
• Constipation is chronic if it persists for 3 or more months.
• One third of adults experience constipation.
• Constipation is more common in the elderly ≥ 65 years.
• According to the ICD 10 Code = K59, the definition for functional constipation includes straining during defecation, small hard stools, feeling of incomplete evacuation, feeling of anal blockage, manually facilitating defecation, and < 3 unassisted bowel movements/week.

• ¼ of defecations for > 3 months includes 2 or more of the symptoms.

• The elderly are prone to constipation due to aging, comorbidities, medications, decreased fiber intake, decreased fluid intake and decreased exercise.
• Objectives of managing constipation: Define, describe, explain risk factors, discuss treatment approach, goals, non-pharmacological, and pharmacological management including laxatives and monitoring parameters.

Pathophysiology of constipation

• Primary constipation is due to dysfunction of the GIT and not identifiable.
• Secondary constipation results from an identifiable cause.
• Primary includes normal/slow transit and pelvic floor dysfunction
• Secondary includes medicines, lifestyle, medical disorders
• Primary and Secondary: Muscle or anal sphincter contraction instead of relaxation.
• GIT structural defects include Bowel obstruction, volvulus, hernia, adhesions, and fecal impaction.
• Medical conditions associated with constipation include Parkinson’s disease, Stroke, Diabetes mellitus, Hypothyroidism, Irritable Bowel Syndrome, Depression, Solid cancers, and Hemorrhoids or anal fissures.
• Medication-induced constipation is linked to various medicines.
• Opioids codeine and morphine
• Anticholinergics
• Antihistamines
• Antispasmodics: Dicyclomine
• Antipsychotics: Thioridazine. Chlorpromazine, clozapine
• Antiparkinsonian medicines: Levodopa
• Cations: Iron, aluminum, calcium, barium, bismuth (e.g. antacids)
• Calcium channel blockers: Diltiazem, verapamil
• Tricyclic antidepressants: Amitriptyline, nortriptyline

Opioid & anticholinergic medicines in constipation

• Opioid containing medicines like morphine/codeine inhibits gastric emptying.
• Opioids increases absorption of fluids and reduces peristalsis in the GI tract.
• Opioids lead to the hardening of stools.
• Anticholinergic medicines e.g. atropine & trihexiphenidyl/benzhexol: relaxes smooth muscles of the gut and slows peristalsis, resulting in constipation.

Medical conditions in constipation

• The GIT is controlled by autonomic nervous system (secretion, movement/contraction and activity of gastrointestinal sphincters, smooth muscles and blood vessels).
• Stroke reduces fluid intake, movement and medicine contributes to constipation.
• Spinal cord lesions injures the nerve that innervates the GIT.

Metabolic disorders

• Diabetes mellitus may cause damage to the vagus nerve - affects control of the movement of food through the GIT.
• This results in the failure to process solid waste leading to constipation.

Lifestyle and behavioral factors

• Lifestyle and behavioral factors include low-fiber diet, reduced fluid intake and decreased physical activity.
• Chronic laxative abuse can cause constipation.
• Psychogenic factors such as ignoring or postponing the urge to defecate.

Clinical presentation

• Important to take history of the condition, frequency of bowel movement, consistency of stool if any, and duration of the symptoms.
• Assess other medical/psychological, including alarm symptoms, family history of colon cancer, age and onset of the symptoms.
• According to the Rome IV criteria, patients should have at least two of the signs and symptoms – applies to a minimum of 25% of bowel movements:
• Less frequent bowel movement (<3 per week)
• Hard, small, dry stools
• Straining
• Feeling of incomplete evacuation
• Feeling of anorectal obstruction or blockage
• Use of physical tactics to defecate

Alarm signs and symptoms

• Alarm signs and symptoms include nausea/vomiting, anorexia/unintentional weight loss ~ 5 kg, anemia, hematochezia/melena and positive fecal occult blood test.
• Severe/persistent constipation refractory to conventional therapy (regardless of age).
• Family history of colon cancer or inflammatory bowel disease.

Diagnosis

• Diagnosis via physical/rectal examination looks for abnormalities, such as masses, strictures, hemorrhoids, fissures, rectal prolapse, and faecal impaction.
• Specific tests include thyroid function test, electrolytes, glucose, full blood count, Barium enema, and colonoscopy.

Management

• Management aims to relieve symptoms, reestablish normal bowel habits and improve quality of life, i.e. prevent adverse effects.
• Combination of non-pharmacological and pharmacological interventions
• Non-pharmacological management involves correcting underlying causes, managing conditions, adjusting/switching medicines.
• Dietary and Life style modification: High-fiber diet (20 - 25g/day) using fiber supplements, increased fruits/vegetables, increased fluid intake (2L/day) and increased physical activity.
• Consider fiber supplements e.g. Psyllium (metamucil) or prunes.
• Surgical management for underlying causes e.g. surgical resection of tumor
• Can involve discontinuation of causative agent/use of alternative agents/lowering dose.

Pharmacological management

• Bulking agents and stool softeners includes Psyllium (Methylcellulose)
• Emollient agents/stool softeners includes Docusate (mineral oil)
• Osmotic agents/stool softeners contains Poorly Absorbed Polyvalent lons
• Magnesium salts or Phosphate-based salts
• Polymers Polyethylene glycol (PEG) low dose
• Carbohydrates, Lactulose, Sorbitol and Glycerin
• Secretory or stimulant cathartics: Soft/semi-solid stool in 6 - 12 hours
• Bisacodyl
• Anthraquinones, e.g. Senna/Senokot
• Castor oil (evacuation)
• Magnesium sulphate
• Those causing water evacuation in 1-6 hours, evacuation of stool: Saline cathartics, Bisacodyl suppostories and PEG-electrolyte lavage

MOA of laxatives

• Osmotic agents (Polyethylene glycol/PEG) is considered first line treatment
• This increases intraluminal osmotic pressure - drawing water into the intestine
• increased volume stimulates peristalsis, working in 3 hours,
• Secretory/stimulant cathartics: Bisacodyl and senokot irritates the intestinal mucosa.
• Stimulates the sub-mucosal and myenteric plexus causing watery evacuation in 1-6 hours
• Emollient agents e.g. Docusate as surfactant allowing water and electrolytes into the stools and bulking making it easier to pass in 1-3 days.
• Emollient agents are used to prevent heart complications following MI or after rectal surgery (NOT opioid induced constipation).
• Other laxatives: Lubiprostone (chloride channel activator) and Linaclotide (peptide = guanylate cyclase agonist)
• Prucalopride: Selective serotonin (5-hydroxytyramine-4) receptor agonist and Opioid receptor antagonists (Alvimopan, Naloxegol, Methylnaltrexone)
• Lubiprostone activates the chloride channel as mechanism of action.
• This increases chloride-rich lumen secretions and increases GIT motility
• Rapid onset of action but poor absorption from GIT. No renal issues, but is high cost – if other response is inadequate
• Linaclotide: binds to guanylate cyclase-C receptor as agonist (GCCA) that binds to guanylate cyclase.

Adverse effects

• Linaclotide activating intracellular cGMP leads to secretion of chloride and bicarbonate into the intestinal lumen, causing increased git motility + accelerated transit time.
• Potential side effects for linaclotide: diarrhea, flatulence & abdominal pain.
• It is not to be used in children < 18 years
• See side effects for Opioid receptor antagonists, Selective serotonin and Prucalopride?
• Preferred first line management is osmotic laxative e.g. PEG+ non-pharmacological interventions.
• If relief not found use Secretory or stimulant cathartics (Bisacodyl, Senna)
• Combined with non-pharmacological interventions.
• For paediatrics, preferred laxative is glycerin suppositories.

Therapeutic outcomes and patients counselling points

• Alleviation of symptoms of constipation.
• Prevent recurrence of of constipation
• Promote appropriate lifestyle modalities
• Improve qol of patients and educate on causes of constipation and laxatives.
• Promote rational use of laxatives to prevent lazy colon.