Functional and infective pathology of the lower GI tract: diarrhoea and constipation Flashcards
(113 cards)
1
Q
What is the suggested definition of diarrhea according to the World Health Organization?
A
‘The passage of three or more loose or liquid stools per day (or more frequent passage than is normal for the individual).’
2
Q
How is acute diarrhea defined?
A
Diarrhea lasting 0-14 days.
3
Q
What is the definition of persistent diarrhea?
A
Diarrhea lasting 14 days to 4 weeks.
4
Q
How is chronic diarrhea defined?
A
Diarrhea lasting 4 or more weeks.
5
Q
Why is diarrhea considered one of the most common symptoms people seek medical attention for?
A
Because it is one of the most common symptoms people experience and consider significant enough to consult a healthcare professional.
6
Q
What is the estimated number of cases of acute diarrhea per year in the UK?
A
Approximately 17 million cases of acute diarrhea occur each year in the UK, potentially affecting up to 25% of the UK population.
7
Q
How many annual GP consultations are attributed to acute diarrhea in the UK?
A
There are approximately 1 million GP consultations per year in the UK related to acute diarrhea.
8
Q
What percentage of the US population is estimated to have chronic diarrhea?
A
Chronic diarrhea is estimated to affect 7-14% of the US population.
9
Q
What are the potential consequences of diarrhea in terms of morbidity and mortality?
A
Diarrhea can cause a significant amount of morbidity (illness) but generally has low mortality (death) rates.
10
Q
What is a major concern associated with diarrhea?
A
Dehydration is a significant concern due to the fluid loss caused by diarrhea.
11
Q
Which populations are at an increased risk of life-threatening illnesses due to diarrhea?
A
Young children and older adults are at an increased risk of developing life-threatening illnesses as a result of diarrhea.
12
Q
What are some potential effects of diarrhea on electrolyte balance?
A
Diarrhea can lead to electrolyte imbalances, including sodium (Na), potassium (K), and bicarbonate (HCO3) levels.
13
Q
How can diarrhea contribute to acidosis?
A
Prolonged diarrhea can lead to acidosis, an imbalance in the body’s acid-base equilibrium.
14
Q
How can chronic diarrhea impact individuals’ well-being?
A
Chronic diarrhea can have negative effects on well-being, mental health, daily activities, dietary choices, and may contribute to social isolation.
15
Q
What is the mechanism of action for osmotic diarrhea?
A
Osmotic diarrhea occurs when non-absorbed hypotonic compounds in the lumen of the intestine increase fluid loss. Examples include ingestion of magnesium-containing antacids, sorbitol, general malabsorption (e.g., pancreatic insufficiency), and specific absorptive defects (e.g., lactose intolerance).
16
Q
What is the mechanism of action for secretory diarrhea?
A
Secretory diarrhea is characterized by increased secretion of substances and ions into the intestinal lumen, coupled with decreased uptake. Examples include enterotoxins (Cholera, E. coli, C. difficile), VIP (Vasoactive Intestinal Peptide), and colonic bile salts and fatty acids following ileal resection.
17
Q
What is the mechanism of action for inflammatory diarrhea?
A
Inflammatory diarrhea occurs when there is an inflamed mucosa, leading to the loss of fluid and blood into the intestinal lumen and decreased absorption of fluid and ions. Examples include Shigella infection, Crohn’s disease, and ulcerative colitis.
18
Q
What is the mechanism of action for abnormal motility diarrhea?
A
Abnormal motility diarrhea is characterized by increased gastrointestinal motility. It can be caused by functional disorders, diabetes, and hyperthyroidism.
19
Q
What is the mechanism of action for overflow/mechanical diarrhea?
A
Overflow/mechanical diarrhea occurs when an obstructing body allows liquid to pass through while solid feces accumulate. Examples include chronic constipation, impaction, and neoplasms.
20
Q
What are some common viral causes of acute diarrhea?
A
Viral causes of acute diarrhea include norovirus and rotavirus.
21
Q
Which bacterial pathogens can cause acute diarrhea?
A
Bacterial causes of acute diarrhea include Salmonella, Campylobacter, Clostridium difficile, and cholera.
22
Q
What are some examples of parasitic causes of acute diarrhea?
A
Parasitic causes of acute diarrhea include Giardia lamblia and Cryptosporidium parvum.
23
Q
Which medications can potentially cause diarrhea?
A
More than 700 medications can cause diarrhea, including laxatives, antibiotics (especially macrolides), and allopurinol.
24
Q
What is meant by “acute presentation of chronic pathology” in the context of diarrhea?
A
It refers to cases where an underlying chronic condition presents with acute episodes of diarrhea, such as in acute appendicitis, intestinal ischemia, or after radiotherapy.
25
What are some other factors that can cause acute diarrhea?
Other causes of acute diarrhea include anxiety, food allergies, and gastrointestinal inflammation (e.g., acute appendicitis, intestinal ischemia, and radiotherapy).
26
What is the most common cause of infectious diarrhea?
Most infectious diarrhea cases are caused by viral infections and are self-limiting.
27
How long does the majority of infectious diarrhea cases last?
Approximately 50% of infectious diarrhea cases last less than 1 day.
28
What is the typical duration of viral infectious diarrhea?
Viral infectious diarrhea typically lasts for 2-3 days.
29
How long does untreated bacterial infectious diarrhea typically last?
Untreated bacterial infectious diarrhea usually lasts for 3-7 days.
30
What is the expected duration of untreated protozoal infectious diarrhea?
Untreated protozoal infectious diarrhea can persist for weeks to months.
31
Is it always necessary to conduct investigations for acute diarrhea?
Investigations may not be needed if the patient is well and the symptoms are short-lived or quickly resolving.
32
When is stool testing (faecal MC&S) typically recommended?
Stool testing, such as faecal microscopy, culture, and sensitivity (MC&S), is particularly useful if the patient is vulnerable, there may be an unusual cause of diarrhea, or there is a need to exclude an infectious cause for public health reasons.
33
What blood tests are commonly performed to investigate acute diarrhea?
Blood tests such as a complete blood count (CBC), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), liver function tests (LFTs), urea and electrolytes (U&Es), and iron studies are often conducted to rule out other acute causes of diarrhea.
34
What is the general management approach for acute diarrhea?
In most cases, no specific treatment is needed for acute diarrhea. Supportive measures focus on maintaining hydration.
35
How can hydration be maintained in cases of acute diarrhea?
Hydration can be maintained by using solutions such as hypertonic saline/glucose solution (e.g., Dioralyte) to replenish electrolytes and fluids lost through diarrhea.
36
When might hospitalization be necessary for acute diarrhea?
Hospitalization may be required if the patient is significantly unwell or at risk of dehydration.
37
When are subsequent diagnostics usually performed for acute diarrhea?
Further diagnostic tests are typically conducted once the acute episode of diarrhea has settled, if deemed necessary.
38
Are antibiotics commonly prescribed for acute diarrhea, even if it is proven to be an infection?
Antibiotics are seldom needed for acute diarrhea, including cases caused by proven infections, unless the diarrhea is severe.
39
What is the most common concern in managing acute diarrhea?
Dehydration is the most common concern in the management of acute diarrhea.
40
How can diet contribute to chronic diarrhea?
Chronic diarrhea can be caused by factors such as malabsorption, artificial sweeteners (with excessive sorbitol), as well as the consumption of caffeine and alcohol.
41
What are some bowel diseases that can cause chronic diarrhea?
Chronic diarrhea can be associated with bowel diseases such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), microscopic colitis, coeliac disease, pancreatic insufficiency, absorption problems, pancreatic and colorectal cancer, small bowel overgrowth, mesenteric ischemia, fistulae, short gut syndrome, Whipple's disease, tropical sprue, amyloidosis, and radiation enteropathy.
42
How can constipation and impaction lead to chronic diarrhea?
Chronic diarrhea can be a result of underlying constipation and impaction, where liquid stool bypasses the impacted stool.
43
What are some common drugs that can cause chronic diarrhea?
Chronic diarrhea can be caused by various drugs, including macrolides, ACE inhibitors, NSAIDs, metformin, DPP4 inhibitors, proton pump inhibitors (PPIs), selective serotonin reuptake inhibitors (SSRIs), oncology drugs, theophyllines, antiarrhythmics, and furosemide.
44
Besides drugs, what are some other causes of chronic diarrhea?
Other causes of chronic diarrhea include infections, endocrine disorders, cystic fibrosis, lymphoma, hormone-secreting tumors (e.g., VIPoma, gastrinoma, carcinoid), autonomic neuropathy, and factitious diarrhea (diarrhea intentionally induced).
45
What are the common tests performed to investigate chronic diarrhea?
The same tests used for investigating acute diarrhea are also conducted for chronic diarrhea. These include stool microscopy, culture, and sensitivity (MC&S), with the addition of parasitology testing to identify potential parasitic causes.
46
Which blood tests are often performed to explore a wider differential diagnosis in chronic diarrhea?
Blood tests such as CA 125, thyroid function tests (TFTs), tissue transglutaminase (tTG) antibody, vitamin B12/folate levels, calcium levels, ferritin levels, and gut hormone levels may be conducted to aid in the evaluation of chronic diarrhea.
47
What additional stool tests may be performed depending on the case of chronic diarrhea?
Additional stool tests that may be considered include quantitative fecal immunochemical test (qFIT) for possible malignancy, fecal calprotectin for suspected inflammatory bowel disease (IBD), and fecal elastase to assess pancreatic exocrine function.
48
What imaging modalities are useful in investigating chronic diarrhea?
Depending on the presentation, imaging modalities such as ultrasound, CT/MRI scans, or endoscopy may be utilized. MRI scans are particularly beneficial for evaluating the small bowel.
49
What is the significance of the quantitative fecal immunochemical test (qFIT)?
qFIT is considered the first-line investigation for evaluating a change in bowel habit and is useful in ruling out bowel cancer.
50
What is the risk of bowel cancer based on the qFIT results?
If the qFIT result is normal (less than 10μg Hb/g of feces), the risk of bowel cancer is approximately 0.4%. If the qFIT result is above 10, the risk increases to 6%, and if it exceeds 150, the risk further rises to 31%.
51
How does qFIT benefit the diagnostic process?
The qFIT test reduces the need for invasive investigations by providing valuable information about the risk of bowel cancer. It helps to identify individuals who may require further investigations and supports appropriate referral decisions.
52
What is the definition of Irritable Bowel Syndrome (IBS) according to NICE?
According to NICE, IBS is characterized by abdominal pain that is either related to defecation or associated with altered stool frequency or appearance. To diagnose IBS, at least two of the following criteria must be met: altered stool passage (straining, urgency, incomplete evacuation), bloating or distension, symptoms worsened by eating, and passing rectal mucus. Additionally, alternative conditions must be excluded.
53
What is the estimated prevalence of IBS in the global population?
The prevalence of IBS in the global population is estimated to be between 5% and 20%, although it is likely underreported.
54
Which age group is most commonly affected by IBS?
IBS most commonly affects individuals between the ages of 20 and 30.
55
Is IBS more common in men or women?
IBS is more common in women.
56
What are some potential factors contributing to the development of IBS?
The exact cause of IBS is unknown, but it may involve genetic factors, dietary factors, gut infections, and psychosocial factors.
57
What is the initial approach to managing IBS?
The initial approach to managing IBS involves ruling out alternative or sinister causes for the symptoms and providing reassurance to the patient.
58
What dietary manipulations can be beneficial for IBS management?
For diarrhea-predominant IBS, reducing insoluble fiber intake (bran, wholemeal flour/bread) and avoiding food triggers such as caffeine, alcohol, and carbonated drinks may be helpful. For constipation-predominant IBS, consuming soluble fiber supplements or foods high in soluble fiber and maintaining adequate fluid intake are recommended. The low FODMAP diet (avoiding fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) can also be effective.
59
Can probiotics be beneficial for managing IBS?
Probiotics may be helpful in managing IBS symptoms.
60
What is a commonly used medication for managing diarrhea-predominant IBS?
Loperamide, an antimotility agent, is commonly used to manage diarrhea in IBS. However, its common side effect is constipation, and higher doses can potentially lead to cardiac arrhythmias.
61
What are antispasmodic drugs used for in IBS management?
Antispasmodic drugs such as hyoscine butylbromide (buscopan), which has antimuscarinic properties, are used to relieve abdominal cramps in IBS.
62
How are constipation-predominant IBS symptoms managed with medication?
Laxatives, particularly bulk-forming agents like ispaghula husk, are used to alleviate constipation in IBS. Lactulose should be avoided as it can cause excessive bloating. Additionally, a low dose of tricyclic antidepressant (such as amitriptyline) can be tried for a 4-week trial, as it has shown to have a positive response in over 90% of patients with varying levels of success.
63
How can constipation be categorized based on time?
Constipation can be categorized as acute when it lasts for 0-3 months and chronic when it persists for 3 months or more.
64
What are the two main causes of constipation?
Constipation can be categorized as primary (functional) or secondary (organic) based on its underlying causes.
65
What is primary (functional) constipation?
Primary constipation refers to constipation that does not have an identifiable organic cause. It is usually due to factors such as diet, lifestyle, inadequate fluid intake, lack of physical activity, or an issue with the functioning of the colon.
66
What is secondary (organic) constipation?
Secondary constipation refers to constipation that is caused by an identifiable organic or structural abnormality. It may be the result of conditions such as intestinal obstruction, hormonal disorders, neurological disorders, or medication side effects.
67
What blood tests are commonly performed to investigate constipation?
Blood tests often include a full blood count (FBC), inflammatory markers, iron studies, liver function tests, thyroid function tests, HbA1c (glycated hemoglobin), calcium, and B12/folate levels.
68
What stool tests are conducted in the investigation of constipation?
Stool tests commonly include the quantitative fecal immunochemical test (qFIT) and calprotectin to assess for potential underlying conditions.
69
What imaging modalities can be used in the investigation of constipation?
Abdominal x-ray is often performed, especially in the acute setting, while a CT scan may be used for more detailed evaluation. Endoscopy, such as colonoscopy or virtual colonoscopy, may also be performed to examine the colon and rectum.
70
What are some special investigations that can be conducted for constipation?
Special investigations for constipation may include a bowel transit study, which assesses the movement of stool through the digestive system, and pelvic floor investigations to evaluate the function of the pelvic floor muscles.
71
What are some common causes of acute constipation?
Acute constipation can be caused by factors such as functional constipation (related to dehydration, diet, and stress), medication use (e.g., opiates, loperamide, iron supplements), and acute presentation of underlying chronic pathology.
72
How can dehydration contribute to acute constipation?
Dehydration can lead to decreased fluid content in the stool, making it harder and more difficult to pass.
73
Which medications can cause acute constipation?
Medications such as opiates (e.g., codeine, morphine), loperamide (antidiarrheal agent), and iron supplements are known to cause constipation as a side effect.
74
What does the term "acute presentation of chronic pathology" mean in the context of constipation?
It refers to cases where a person with an underlying chronic condition experiences an acute episode of constipation, which may indicate a worsening or complication of their existing condition. In some cases, bowel obstruction can be the underlying cause.
75
How do opiates cause constipation?
Opiates exert their effects through various opioid receptors, predominantly the μ receptors in the gastrointestinal (GI) tract. Activation of μ receptors, particularly μ2, leads to reduced GI motility and increased sphincter tone, resulting in constipation. The binding of loperamide to μ receptors specifically promotes constipation.
76
What are some common causes of chronic constipation?
Chronic constipation can be caused by factors such as functional constipation (related to dehydration, diet, stress, IBS, pregnancy, and withholding), medication use (including opiates, loperamide, iron supplements, calcium channel blockers, and antimuscarinics), colonic conditions (cancer, IBD with stricturing, diverticular disease, extrinsic compression), pelvic floor/defecatory disorders (rectal prolapse, rectocele, pelvic floor dyssynergia, megarectum), endocrine disorders (hypothyroidism, hypercalcemia, diabetes mellitus, porphyria), and neurological conditions (MS, spinal cord lesions, Parkinson's disease, Hirschsprung's disease).
77
What are some colonic causes of chronic constipation?
Colonic causes of chronic constipation include conditions such as cancer, inflammatory bowel disease (IBD) with stricturing, diverticular disease, extrinsic compression (rare), and painful conditions like anal fissures.
78
What are some pelvic floor/defecatory disorders that can lead to chronic constipation?
Pelvic floor/defecatory disorders such as rectal prolapse, rectocele, pelvic floor dyssynergia, and megarectum can contribute to chronic constipation.
79
What are some endocrine and neurological conditions associated with chronic constipation?
Endocrine disorders such as hypothyroidism, hypercalcemia, diabetes mellitus, and porphyria, as well as neurological conditions like multiple sclerosis (MS), spinal cord lesions, Parkinson's disease, and Hirschsprung's disease, can cause chronic constipation.
80
What is the initial step in managing chronic constipation?
The initial step is to remove any identifiable insults or underlying causes contributing to constipation. However, this is not always possible.
81
How can the environment be made favorable for bowel movements in chronic constipation management?
Measures can be taken to create a favorable environment for bowel opening, including ensuring adequate fiber and fluid intake, increasing physical activity, discontinuing constipating medications, and promoting correct toilet behavior (such as not ignoring the urge to defecate, which is common in children).
82
What should be addressed first if fecal impaction is present in chronic constipation?
If fecal impaction is present, it should be resolved first. This can be achieved through enemas, suppositories, and in rare cases, manual evacuation may be necessary.
83
What role do laxatives play in the management of chronic constipation?
Laxatives are commonly used to alleviate constipation. They help soften the stool and promote bowel movements.
84
What are some advanced treatment options for chronic constipation?
Advanced treatment options for chronic constipation include neuromodulation, such as sacral nerve stimulation, and surgical interventions like (sub)total colectomy or stoma creation.
85
What is diverticular disease?
Diverticular disease refers to the protrusion of mucosal pouches through the muscular wall of the bowel.
86
What is the relationship between diverticular disease and constipation?
Diverticular disease is intimately linked with constipation, although it is unclear whether constipation is the cause or the effect of diverticular disease, or if both conditions influence each other.
87
What is the role of dietary fiber in diverticular disease?
Poor dietary fiber intake is implicated in the development and progression of diverticular disease. Insufficient fiber intake can contribute to both constipation and the formation of diverticula.
88
Where is the highest incidence of diverticular disease seen?
Diverticular disease has the highest incidence in Western countries. In the UK, over 60% of people over the age of 70 have diverticula.
89
In which anatomical location of the colon is diverticular disease most commonly found?
Diverticular disease is most commonly found in the sigmoid colon, which has the highest intra-luminal pressure in the colon.
90
What percentage of people with diverticular disease experience symptoms?
More than 90% of people with diverticular disease have no symptoms and are considered asymptomatic.
91
What is the characteristic feature of proximal bowel obstruction?
In proximal bowel obstruction, the bowels may still be functional despite the obstruction. This can make the patient's history misleading.
92
What is meant by "absolute constipation" in the context of bowel obstruction?
"Absolute constipation" refers to the absence of passage of stool or flatus. It is often indicative of a distal mechanical obstruction of the colon.
93
Why is it important to establish the cause of bowel obstruction quickly?
Establishing the cause of bowel obstruction quickly is crucial as it helps determine if spontaneous resolution is possible or if surgical intervention is necessary. Timely management is essential for the best outcome.
94
Can adhesional small bowel obstruction resolve without surgery?
Yes, adhesional small bowel obstruction can resolve without surgery in over 90% of cases. Spontaneous resolution is possible, but close monitoring and medical management are needed.
95
What are some common causes of bowel obstruction?
Common causes of bowel obstruction include extrinsic factors such as abdominal masses, adhesions/scar tissue, hernias, and neoplasia, as well as intrinsic factors such as inflammatory strictures/narrowing and luminal causes like bezoars or foreign bodies.
96
What is the initial management approach for suspected bowel obstruction?
If a patient is unwell, immediate resuscitation is required. Early investigation is essential, and computed tomography (CT) is highly sensitive and specific for diagnosing bowel obstruction.
97
What decision needs to be made in the management of bowel obstruction?
The decision is whether the obstruction will settle on its own or if intervention is necessary. "Closed loop" large bowel obstruction, in particular, is considered an emergency situation.
98
What is the significance of a competent ileocaecal valve in bowel obstruction?
A competent ileocaecal valve, which prevents reflux into the ileum, is present in about 50% of cases and can help determine the management approach.
99
What should be considered when a patient presents with right lower abdominal pain and an obstructed colon?
When encountering a patient with right lower abdominal pain and an obstructed colon, caution should be exercised as this presentation may suggest a potential surgical emergency.
100
What are some key features to consider in the context of bowel cancer?
Bowel cancer can present with vague or no gastrointestinal symptoms. It is important to assess any changes from a person's normal bowel habits. Iron deficiency anemia and an elevated quantitative fecal immunochemical test (qFIT) increase concerns for bowel cancer.
101
What is the incidence of colorectal cancer in the UK?
In the UK, there are approximately 40,000 new cases of colorectal cancer each year.
102
What is the incidence of anal cancer in the UK?
In the UK, there are approximately 1,000 new cases of anal cancer per year.
103
What is the 5-year survival rate for both colorectal and anal cancers?
The 5-year survival rate for both colorectal cancer and anal cancer is approximately 60%.
104
What are examples of bulk laxatives?
Examples of bulk laxatives include Ispaghula husk (brand name Fybogel) and Methylcellulose. These indigestible polysaccharides increase luminal volume, stimulate the enteric reflex, and promote peristalsis.
105
What are examples of osmotic laxatives?
Examples of osmotic laxatives include Lactulose, macrogols (brand name Movicol), and phosphate enemas (brand name Cleen). These substances, when poorly absorbed, increase water content in the lumen, soften the stool, and stimulate peristalsis through the enteric reflex.
106
What are examples of stimulant laxatives?
Examples of stimulant laxatives include Senna, co-danthramer, bisacodyl, sodium picosulfate, and glycerol enema. These laxatives increase peristalsis by acting on mucosal nerves. Co-danthramer is potentially carcinogenic and is often used in palliative care, while glycerol acts as a stimulant and lubricant.
107
What are examples of faecal softeners/lubricants?
Examples of faecal softeners/lubricants include Docusate sodium (brand name Docusate) and Arachis oil or liquid paraffin enema. Docusate sodium acts as a surfactant, increasing water and lipid absorption into the stool to soften it. Arachis oil and liquid paraffin lubricate the stool.
108
What is Linaclotide?
Linaclotide is a medication that acts as a guanylate cyclase-C receptor agonist. It increases intestinal fluid secretion (chloride and bicarbonate) into the lumen, thereby increasing intestinal volume. Linaclotide is used in the treatment of irritable bowel syndrome (IBS) and can help decrease visceral pain.
109
What is Prucalopride?
Prucalopride is a selective serotonin 5HT4 receptor agonist. It functions as a prokinetic agent rather than a true laxative. Prucalopride is primarily used for the treatment of slow transit constipation, helping to enhance gut motility.
110
What is the role of Erythromycin as a laxative?
Erythromycin, which is a macrolide antibiotic, possesses prokinetic qualities. It can stimulate gut motility and is sometimes used as a prokinetic agent in cases of constipation.
111
What are some common side effects of laxatives?
Common side effects of laxatives include diarrhea or excessive flatus (gas), bloating (particularly with bulk-forming and osmotic laxatives), cramps (seen with osmotic and stimulant laxatives), and rarely electrolyte imbalances.
112
Which type of laxatives is most commonly associated with electrolyte imbalances?
Purgative laxatives, particularly those used for bowel preparation such as Picolax or Moviprep, can cause large fluid and electrolyte losses, potentially leading to electrolyte imbalances. This is less common with other types of laxatives.
113
What should be considered when using laxatives in cases of suspected partial bowel obstruction?
Caution should be exercised when using laxatives in cases of suspected partial bowel obstruction, as they can potentially worsen the obstruction or lead to bowel perforation. A thorough evaluation is needed before initiating laxative use in such cases.
