Constipation Causes, Diagnosis & Treatment Options

What is Constipation?

Infrequent bowel movements and/or difficulty in bowel movements, often accompanied by straining or a sense of incomplete evacuation.

Classification 

• Primary constipation
• Secondary constipation

Causes of Secondary Constipation

Drugs

• Calcium channel blockers
• Opioids
• NSAIDs
• Calcium

Endocrinopathies

• Hypothyroidism
• Hypercalcemia
• Diabetes mellitus

Neurological Disorders

• Stroke
• Parkinson's disease
• Amyotrophic lateral sclerosis (ALS)

Obstructive Causes

• Carcinoma of the colon
• Rectal cancers

Metabolic Causes

• Hypokalemia
• Hypomagnesemia

Also read: INI-CET Exam Analysis: November '24 Session

Classification of Primary Constipation

Normal Colonic Transit Time

• Functional constipation
• Increased risk for females, stress, depression, decreased dietary consumption of fibers, and debility
• Increased need for straining

Slow Colonic Transit Time

• Defects in myenteric plexus
• Hirschsprung disease
• Bloating
• Abdominal distension

Anorectal Dysfunction or Dyssynergic Defecation

• Colonic transit is normal, but the rectal sphincter fails to contract correctly
• Rectal pain or fullness
• Need frequent manual evacuation

Martelli's Regimen For Colonic Transit Time

Abdominal X-ray

• 1 capsule containing 20 radioactive markers
• Normally, > 80% of markers are expelled at the end of 5 days
• < 80% expulsion indicative of slow colonic transit time
• It can help identify the affected part of the colon, i.e., the right colon, left colon, or recto-sigmoid region.

Balloon Expulsion Test

• The patient lies in the left lateral decubitus position or squats on a toilet seat.
• A balloon filled with 50 ml of water or air is inserted, and the patient is asked to expel.
• Expulsion in < 2 minutes—normal
• Expulsion in > 2 minutes is indicative of dyssynergia
• Functional abnormality
• Poor response to laxatives

Also read: Amputation and Different Types in Orthopedics

Approach to Constipation

• 90% of cases are primary constipation.
• A detailed investigation is required if red flag signs are present:
  • Age > 50 years
  • Bleeding per rectum or blood in the stool
  • New-onset constipation
  • Weight loss > 10% of body weight within 6 months

History

Physical Examination

Test Results

Examinations

• Thyroid-stimulating hormone (TSH) test
• Complete blood count
• Electrolytes
• X-ray abdomen

Further Approaches

• If a secondary cause is found: Treat accordingly
• Supplement with fiber and laxatives

Also read: Physical and Chemical Methods of Sterilization: Techniques and Controls

Treatment for Constipation

Approach to Primary Constipation

• PEG compounds-preferred
  • Unabsorbed
  • Not acted upon by bacterial enzymes
• Lactulose
  • Flatulence
  • Partially absorbed

Classification of Laxatives

Bulk-forming Laxatives

• Do not stimulate peristalsis or initiate any biochemical change in the intestinal milieu
• Add bulk to stool, stimulating colonic movement
• Dietary fiber
• Methylcellulose

Osmotic Laxatives

• 1st line agent
• Lactulose
• Polyethylene glycol (PEG)
• Magnesium salts
• Mechanism of action:
  • Osmotically active
  • Attract water from the colon to bulk the stool.

Stimulant Laxatives

• Stimulate colonic peristalsis
• Bisacodyl

Secretory Laxatives

• Increase active secretion of chloride ions into a bowel movement
• An electrical imbalance develops, initiating the pumping of positive ions (sodium) into the lumen.
• There are more sodium and chloride ions in the lumen compared to the colonic cells.
• The osmotic gradient stimulates the movement of water into the lumen.
• Lubiprostone
  • Chloride channel stimulator
• Linaclotide
  • Guanylyl cyclase stimulator

Also read: Staphylococcaceae : Staphylococcus aureus and Clinical Implications

Functional Constipation

1. Functional Constipation is a type of primary constipation

2. Diagnosis: Rome IV Criteria

Rome IV criteria can also be used for:

1. Functional dyspepsia

2. Irritable bowel syndrome

3. Functional chest pain related to esophageal origin

Differential Diagnosis

Constipation Predominant Irritable Bowel Syndrome (IBS-C)

Criteria for Functional Constipation Diagnosis

The onset of constipation symptoms at least six months before diagnosis.

Below criteria met for the past 3 months

1. Two or more of the following criteria must be present:

• Straining with > 25% defecations
• Lumpy or hard stools with more than 25% of defecation
  • Bristol stool form types 1 and 2
• The sensation of incomplete evacuation with more than 25 % of defecations
• The sensation of anorectal obstruction or blockage with more than 25% of defecations
• Manual maneuvers are required, with more than 25 % of defecations
  • E.g., digital evacuations, support for the pelvic floor
• Fewer than 3 spontaneous defecations per week

2. Loose stools are rare without the administration of laxatives

3. Insufficient criteria for irritable bowel syndrome

Also read: Coccidian Parasites: Toxoplasma Gondii

Patient Complaint

• Pain is a rare feature of functional constipation. If there is frequent pain present, it should suggest irritable bowel syndrome.
• There are no red flag signs.
  • Age more than 50
  • Significant weight loss
  • Blood in stool
  • Anemia
  • Fecal occult blood positive

Constipation Management

• Lifestyle modification (includes a good amount of mobility)
• Increased dietary fibers
• Stool bulking agents
• Pharmacotherapy.
  • DOC: Osmotic Laxatives
  • PEG > Lactulose
• 2nd Line Agents
  • Stimulant Laxatives
  • Secretory Laxatives
• Most patients respond well to lifestyle modification

Also read: Miscellaneous Pathogenic Bacteria

Important MCQs

A 40-year-old female was evaluated for primary constipation. Colonic transit time was tested. The patient was given a capsule containing 20 radiopaque markers orally. An abdominal X-ray was obtained daily. After 5 days, an X-ray showed 3 radiopaque markers still in the colon. Which type of constipation is the patient suffering from? 

1. Slow transit
2. Normal transit
3. Anorectal dysfunction
4. Rapid transit

Answer: A. Slow transit

• Females have a higher risk of constipation compared to males.

Q2: Balloon expulsion test is used for the diagnosis of 

1. Slow transit constipation
2. Dyssynergic defecation
3. Normal transit defecation
4. Fissure-in-ano

Ans.: B. Dyssynergic defecation

Q3: Which of the following is considered a first-line agent for the treatment of chronic constipation? 

1. Osmotic laxatives
2. Stimulant laxatives
3. Secretory laxatives
4. Any of the above

Ans.: A. Osmotic laxatives

Q4: Mechanism of action of linaclotide: 

1. Chloride channel activator
2. Prokinetic
3. Guanylyl cyclase stimulator
4. 5-HT4 agonist

Ans.: C. Guanylyl cyclase stimulator

Download the PrepLadder app now and unlock a 24-hour FREE trial of premium high-yield content. Access Video Lectures, digital notes, QBank, and Mock Tests for FREE to start with the Best NEET PG Coaching Online. Elevate your study experience and gear up for success. Start your journey with PrepLadder today!