PHM101: Constipation in Medicine
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Questions and Answers

What is constipation characterized by?

  • Normal bowel function
  • Frequent, complete, and easy defecation
  • Difficult, infrequent, or seemingly incomplete defecation (correct)
  • Increased gut motility

    • What is the prevalence of constipation in North America?

  • 12-19% (correct)
  • 5-10%
  • 1.9-5%
  • 25-30%

    • What is the most common subtype of constipation?

  • Slow transit
  • Pelvic floor muscle dysfunction
  • Normal transit (functional constipation) (correct)
  • Disorders of defecation

    • What is the primary function of parasympathetic activity in the colon?

    <p>Peristalsis and propelling colonic contents forward</p> Signup and view all the answers

    What percentage of fluid is absorbed by the colon?

    <p>90%</p> Signup and view all the answers

    What is the mediator of parasympathetic tone in the colon?

    <p>Acetylcholine</p> Signup and view all the answers

    What is a risk factor for constipation?

    <p>Lack of exercise</p> Signup and view all the answers

    What is the primary goal of understanding the pathophysiology of constipation?

    <p>To understand the underlying mechanisms of the condition</p> Signup and view all the answers

    What type of constipation is due to lifestyle, medical disorders, or drugs?

    <p>Secondary constipation</p> Signup and view all the answers

    Why is it essential to ask questions before recommending a laxative to a patient?

    <p>All of the above</p> Signup and view all the answers

    What regulates defecation?

    <p>Pelvic floor muscles and anal sphincters</p> Signup and view all the answers

    What is a common drug-induced cause of constipation?

    <p>Hydromorphone</p> Signup and view all the answers

    What is considered a 'normal' frequency for bowel movements?

    <p>One per day</p> Signup and view all the answers

    What is the primary reason for counselling a patient with a prescription for hydromorphone?

    <p>To discuss the risk of constipation</p> Signup and view all the answers

    What is the primary goal of nonpharmacologic options in the prevention and treatment of constipation?

    <p>To increase fibre intake</p> Signup and view all the answers

    Why is it essential to compare and contrast different laxative classes?

    <p>To understand the pharmacology, indications, and efficacy of each class</p> Signup and view all the answers

    What is a common complication of constipation?

    <p>Haemorrhoids</p> Signup and view all the answers

    Why is prophylactic therapy necessary for patients taking opioids like hydromorphone?

    <p>To reduce the risk of constipation</p> Signup and view all the answers

    What is a risk factor for constipation in elderly individuals aged over 65 years?

    <p>↓ dietary fibre</p> Signup and view all the answers

    Which of the following is a neurogenic cause of constipation?

    <p>Diabetic autonomic gastroparesis</p> Signup and view all the answers

    What is a contributing factor to constipation in children?

    <p>Transition to solid food</p> Signup and view all the answers

    Which of the following drug classes can cause constipation?

    <p>All of the above</p> Signup and view all the answers

    What is a risk factor for constipation in pregnant women?

    <p>Hormonal changes in colonic motility</p> Signup and view all the answers

    Which of the following is NOT a risk factor for constipation?

    <p>↑ dietary fibre</p> Signup and view all the answers

    What is a complication of spinal cord injury that can contribute to constipation?

    <p>↓ sensation of rectal fullness</p> Signup and view all the answers

    Which of the following drugs has anticholinergic properties?

    <p>Dimenhydrinate</p> Signup and view all the answers

    What is a risk factor for constipation in individuals with diabetes?

    <p>Autonomic dysfunction</p> Signup and view all the answers

    What is the name of the antispasmodic drug that can cause constipation?

    <p>Oxybutynin</p> Signup and view all the answers

    What is the main symptom of constipation?

    <p>Hard stool and difficulty defecating</p> Signup and view all the answers

    According to the Rome IV criteria, what is the minimum frequency of defecations per week to diagnose constipation?

    <p>&lt; 3 defecations per week</p> Signup and view all the answers

    What is a common complication of constipation?

    <p>Hemorrhoids</p> Signup and view all the answers

    What is the first step in diagnosing constipation?

    <p>History and physical exam</p> Signup and view all the answers

    What is the purpose of a flat plate abdomen X-ray in diagnosing constipation?

    <p>To identify structural causes of constipation</p> Signup and view all the answers

    What is an important aspect of a physical exam in diagnosing constipation?

    <p>Rectal exam</p> Signup and view all the answers

    What is a recommended prevention strategy for constipation?

    <p>Increasing fiber intake</p> Signup and view all the answers

    What is a medication that can cause constipation as a side effect?

    <p>Oxybutynin</p> Signup and view all the answers

    What is the primary concern in laxative abuse?

    <p>Psychological dependency</p> Signup and view all the answers

    Which of the following medications may be contributing to Helen's constipation?

    <p>Amitriptyline</p> Signup and view all the answers

    What is the primary difference between acute treatment and chronic prophylaxis for constipation?

    <p>Onset of effect in the disease</p> Signup and view all the answers

    What is a common misconception about bowel movement frequency?

    <p>Bowel movements should occur daily</p> Signup and view all the answers

    What is a potential complication of laxative abuse?

    <p>All of the above</p> Signup and view all the answers

    Why is it essential to consider the relevance of onset of effect in disease when treating constipation?

    <p>To ensure the medication is effective in the acute treatment phase</p> Signup and view all the answers

    What is the primary mechanism by which somatostatin regulates colonic motility, and how does it contribute to constipation?

    <p>Somatostatin inhibits the release of acetylcholine, reducing parasympathetic tone and slowing colonic motility, leading to constipation.</p> Signup and view all the answers

    How does decreased physical activity contribute to constipation in the elderly, and what are some potential underlying mechanisms?

    <p>Decreased physical activity in the elderly leads to decreased motility, slowed gut transit time, and increased water absorption, contributing to constipation. Underlying mechanisms include decreased parasympathetic tone, reduced muscle mass, and altered gut microbiota.</p> Signup and view all the answers

    What is neurogenic constipation, and how does it differ from other subtypes of constipation?

    <p>Neurogenic constipation is a subtype of constipation characterized by dysfunction of the nervous system, leading to impaired gut motility and sensation. It differs from other subtypes in that it is caused by neurological disorders or injuries, rather than solely by gut dysfunction.</p> Signup and view all the answers

    How does the parasympathetic nervous system regulate colonic motility, and what is the main neurotransmitter involved?

    <p>The parasympathetic nervous system stimulates colonic motility through the release of acetylcholine, which increases muscle contraction and promotes peristalsis.</p> Signup and view all the answers

    What are some common pharmacological causes of constipation, and how do they affect gut motility?

    <p>Common pharmacological causes of constipation include opioids, anticholinergics, and antihistamines. These medications decrease gut motility by inhibiting the release of acetylcholine, reducing parasympathetic tone, and increasing water absorption.</p> Signup and view all the answers

    How does a lack of fiber in the diet contribute to constipation, and what are some potential mechanisms involved?

    <p>A lack of fiber in the diet leads to constipation by reducing stool bulk, slowing gut transit time, and increasing water absorption. Fiber helps to stimulate colonic motility and promotes the growth of beneficial gut microbiota.</p> Signup and view all the answers

    What is the primary difference between primary and secondary constipation, and how are they diagnosed?

    <p>Primary constipation has no identifiable underlying cause, while secondary constipation is caused by lifestyle factors, medical disorders, or medications. Diagnosis involves ruling out underlying causes and assessing bowel habits, abdominal symptoms, and gut function.</p> Signup and view all the answers

    What is the primary mechanism of action of bulk-forming laxatives such as psyllium and methylcellulose?

    <p>Increasing stool bulk, retention of stool water, and transit time</p> Signup and view all the answers

    Why is it essential to increase fluid intake when taking soluble fibre or bulk-forming laxatives?

    <p>To prevent constipation and promote regular bowel movements</p> Signup and view all the answers

    What is the primary mechanism by which opioids contribute to constipation?

    <p>Opioids decrease gut motility and increase intestinal transit time, leading to constipation.</p> Signup and view all the answers

    What is the primary difference between acute treatment and chronic prophylaxis for constipation?

    <p>Acute treatment involves periodic use of laxatives, while chronic prophylaxis involves long-term use of laxatives to prevent constipation</p> Signup and view all the answers

    Why is it essential to assess the efficacy of laxatives in patients with constipation?

    <p>To determine the effectiveness of treatment and adjust therapy as needed</p> Signup and view all the answers

    Which of the following is a common contributing factor to constipation in elderly individuals?

    <p>↓ dietary fibre intake</p> Signup and view all the answers

    What is the effect of spinal cord injury (SCI) on rectal tone and sensation of rectal fullness?

    <p>↓ rectal tone and ↓ sensation of rectal fullness</p> Signup and view all the answers

    What is a common complication of constipation in elderly individuals aged over 65 years?

    <p>Fecal impaction</p> Signup and view all the answers

    What is the primary role of the parasympathetic nervous system in gut motility?

    <p>Stimulation of gut motility</p> Signup and view all the answers

    What is a neurogenic cause of constipation?

    <p>Spinal cord injury</p> Signup and view all the answers

    What is a contributing factor to constipation in children?

    <p>Diet low in fibre</p> Signup and view all the answers

    What is a common cause of constipation in pregnant women?

    <p>Hormonal changes in colonic motility</p> Signup and view all the answers

    Which of the following drugs does NOT have anticholinergic properties?

    <p>Misoprostil</p> Signup and view all the answers

    What is a common pharmacological cause of constipation?

    <p>Opioids</p> Signup and view all the answers

    What is a common complication of diabetic autonomic neuropathy in relation to constipation?

    <p>Gastroparesis</p> Signup and view all the answers

    Why is it essential to consider the relevance of onset of effect in disease when treating constipation?

    <p>To choose the most appropriate laxative or treatment strategy</p> Signup and view all the answers

    What is the primary mechanism by which anticholinergic medications, such as oxybutynin, contribute to constipation?

    <p>Anticholinergic medications, such as oxybutynin, contribute to constipation by inhibiting the parasympathetic nervous system, which regulates the contraction of smooth muscle in the intestines, leading to decreased motility and increased transit time.</p> Signup and view all the answers

    What are the specific risk factors that contribute to constipation in elderly individuals aged over 65 years?

    <p>Risk factors for constipation in elderly individuals aged over 65 years include decreased mobility, decreased fiber intake, medication use, and underlying medical conditions such as diabetes and hypothyroidism.</p> Signup and view all the answers

    What is the primary mechanism by which neurogenic disorders, such as spinal cord injury, contribute to constipation?

    <p>Neurogenic disorders, such as spinal cord injury, contribute to constipation by disrupting the normal neural regulation of the gut, leading to decreased motility and increased transit time.</p> Signup and view all the answers

    What is the role of the parasympathetic nervous system in regulating gut motility and how does it contribute to constipation?

    <p>The parasympathetic nervous system regulates gut motility by stimulating the contraction of smooth muscle in the intestines, and its inhibition can lead to decreased motility and constipation.</p> Signup and view all the answers

    What are the primary causes of constipation, and how do they contribute to the development of this condition?

    <p>The primary causes of constipation include lifestyle factors, medical disorders, and medication use, which can contribute to decreased motility, increased transit time, and abnormal gut function.</p> Signup and view all the answers

    What is the role of the colon in regulating water and electrolyte absorption, and how does it contribute to the development of constipation?

    <p>The colon regulates water and electrolyte absorption by absorbing fluid and electrolytes, and its dysfunction can lead to constipation by reducing the frequency and liquidity of stools.</p> Signup and view all the answers

    What is the primary difference between acute treatment and chronic prophylaxis for constipation, and how do they relate to the underlying causes of this condition?

    <p>Acute treatment for constipation focuses on relieving symptoms, whereas chronic prophylaxis aims to prevent recurrence, and the choice of treatment depends on the underlying causes of constipation, such as lifestyle factors, medical disorders, or medication use.</p> Signup and view all the answers

    Study Notes

    Constipation - Definition and Epidemiology

    • Constipation is a bowel disorder characterized by difficult, infrequent, or seemingly incomplete defecation that does not meet the criteria for irritable bowel syndrome.
    • Definition: fewer than 3 BM's/week, > 3 days without a BM, straining > 25% of the time.
    • Epidemiology: common in North America (1.9-27%), more common in females, elderly, and can be associated with serious complications.

    Constipation Subtypes

    • Normal transit (functional constipation): most common, difficulty evacuating, hard stool, abdominal discomfort.
    • Slow transit: ↑ GI transit time.
    • Disorders of defecation: pelvic floor muscle or anal sphincter dysfunction.

    Normal Colonic Physiology

    • Smooth muscle: parasympathetic activity responsible for peristalsis, which propels colonic contents forward.
    • Colon absorbs 90% of fluid presented to it (1.5-2L).
    • Defecation regulated by pelvic floor muscles and anal sphincters.

    Risk Factors for Constipation

    • Lifestyle: ↓ dietary fibre, inadequate fluid intake, inactivity.
    • GI disorders: irritable bowel syndrome, diverticulitis, anal/rectal diseases, tumours.
    • Neurogenic: spinal cord injury, CNS trauma, tumours, strokes, multiple sclerosis, Parkinson's disease.
    • Endocrine disorders: hypothyroidism, diabetes (autonomic dysfunction).
    • Pregnancy: hormonal changes in colonic motility, pressure of enlarged uterus on colon.
    • Elderly: ↓ dietary fibre, ↓ physical activity, medications, co-morbidities (e.g., diabetes, hypothyroidism).
    • Children: transition to solid food, toilet training, entry to school.

    Drug-Induced Constipation

    • Anticholinergics: first generation antihistamines, tricyclic antidepressants, antiparkinson drugs, oxybutynin.
    • Opioids: aluminum or calcium antacids, iron preparations, calcium channel blockers, diuretics.
    • All of the above drug classes can cause constipation except misoprostol.

    Clinical Presentation and Diagnosis

    • Clinical presentation: hard stool, difficulty defecating, sensation of incomplete defecation, bloating, distension, abdominal pain.
    • Diagnosis: Rome IV criteria, history and physical exam, response to empiric therapy, routine labs and diagnostic imaging not recommended unless alarm symptoms.

    Management and Prevention

    • Prevention: ↑ dietary fibre, fluid intake, exercise, choice of medication, prophylactic laxatives in high-risk individuals.
    • Acute treatment vs chronic prophylaxis: relevance of onset of effect in disease.
    • Nonpharmacologic options: dietary fibre, fluid intake, exercise, lifestyle modifications.

    Laxative Abuse

    • Misperceptions about normal bowel movement frequency.
    • Psychological dependency, ?physical dependency (“lazy colon”).
    • Fluid and electrolyte disturbances, weight loss strategy.

    Case Study

    • Helen is a 73-year-old female with hard, lumpy stools, PMH: hypothyroidism, hypertension, type 2 diabetes, diabetic neuropathy.
    • Could this be caused by drug therapy? Can this be treated with drug therapy?
    • If so, what would be effective and safe alternatives for Helen?

    Constipation

    • Definition: A bowel disorder characterized by difficult, infrequent, or seemingly incomplete defecation that does not meet the criteria for irritable bowel syndrome.
    • Criteria: Fewer than 3 bowel movements (BM) per week, more than 3 days without a BM, or straining more than 25% of the time.
    • Prevalence: Common in North America, affecting 1.9-27% of the population, with a higher incidence in females and the elderly.

    Types of Constipation

    • Primary constipation: No identifiable cause.
    • Secondary constipation: Due to lifestyle, medical disorders, or drugs.
    • Subtypes:
      • Normal transit (functional constipation): Most common, characterized by difficulty evacuating, hard stool, and abdominal discomfort.
      • Slow transit: Increased gastrointestinal transit time.
      • Disorders of defecation: Pelvic floor muscle or anal sphincter dysfunction.

    Normal Colonic Physiology

    • Smooth muscle: Responsible for peristalsis, which propels colonic contents forward.
    • Parasympathetic activity: Regulates peristalsis.
    • Colon function: Absorbs 90% of fluid presented to it (1.5-2L).
    • Defecation regulation: Regulated by pelvic floor muscles and anal sphincters.

    Risk Factors for Constipation

    • Lifestyle factors:
      • Lack of dietary fiber.
      • Inadequate fluid intake.
      • Inactivity.
    • Neurogenic factors:
      • Spinal cord injury.
      • CNS trauma or tumors.
      • Strokes.
      • Multiple sclerosis.
      • Parkinson's disease.
    • Endocrine disorders:
      • Hypothyroidism.
      • Diabetes (autonomic dysfunction).
      • Hypercalcemia.
    • Pregnancy: Hormonal changes in colonic motility, pressure of enlarged uterus on colon, and use of iron and calcium supplements.
    • Medications: Anticholinergics, opioids, iron, calcium channel blockers, and diuretics.

    Clinical Presentation

    • Hard stool, difficulty defecating, and sensation of incomplete defecation.
    • Bloating, distention, and abdominal pain.
    • Diagnosis: Based on Rome criteria, which include at least 2 of the following symptoms in the previous 3 months:
      • Straining > 25% of defecations.
      • Lumpy or hard stool > 25% of defecations.
      • Sensation of incomplete defecation > 25% of defecations.
      • Sensation of blockage > 25% of defecations.
      • Manual maneuvers to facilitate > 25% of defecations.
      • < 3 defecations per week.
      • Loose stools rare without use of laxatives.
    • Complications: Hemorrhoids, rectal prolapse, anal fissures, bowel obstruction/impaction, and fecal incontinence (overflow diarrhea).

    Diagnosis and Management

    • History and physical exam: Important for diagnosis.
    • Response to empiric therapy: Helpful in diagnosing constipation.
    • Routine labs and diagnostic imaging: Not recommended unless alarm symptoms are present.
    • Labs based on suspicion of underlying cause: e.g., TSH for hypothyroidism, Ca for hypercalcemia of malignancy.
    • Flat plate abdomen: Used to diagnose structural causes.
    • Barium enema and colonoscopy: Used to diagnose structural causes.
    • Alarm symptoms: Unintended weight loss, hematochezia, family history of colorectal cancer or IBD, and anemia.
    • Prevention: Increase dietary fiber, fluid intake, and exercise, and choose medications that do not cause constipation.
    • Treatment: Correct underlying cause, use laxatives, and perform manual disimpaction if necessary.
    • Non-pharmacologic strategies: Increase dietary fiber, fluid intake, and exercise, and use bowel training to prevent constipation.

    Laxatives

    • Types:
      • Bulk-forming laxatives (e.g., psyllium, methylcellulose).
      • Stool softeners/emollients (e.g., docusate).
      • Lubricants (e.g., mineral oil).
      • Stimulants (e.g., senna, bisacodyl, cascara).
      • Osmotic laxatives/saline cathartics (e.g., PEG, lactulose, sorbitol, magnesium).
      • Opioid receptor antagonists (e.g., naloxegol, methylnaltrexone).
      • Serotonin 5-HT4 receptor agonist (e.g., prucalopride).
      • Guanylate cyclase C receptor agonist (e.g., linaclotide).
    • Administration: Oral and rectal (suppositories and enemas).

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