General Medicine
Diarrhoeal Disorders
Diarrhoeal disorders for MBBS: acute versus chronic diarrhoea, dehydration and oral rehydration, parasitic causes and inflammatory bowel disease, mapped to NMC codes IM16.1 to IM16.17.
MedNext Academy | 3 min read
Diarrhoeal Disorders
Diarrhoeal disorders for MBBS: acute versus chronic diarrhoea, dehydration and oral rehydration, parasitic causes and inflammatory bowel disease, mapped to NMC codes IM16.1 to IM16.17.
This chapter covers acute and chronic diarrhoea, with emphasis on assessing dehydration and the central role of oral rehydration. It works through the common infective causes and their stool findings, the rational use of antibiotics, and the distinction and management of Crohn disease and ulcerative colitis.
High-yield: Diarrhoeal Disorders
- Diarrhoea is defined as loose or watery stools three or more times a day and is classified as acute or chronic by duration.
- Acute diarrhoea is usually infective, while chronic diarrhoea has a broader differential including malabsorption and inflammatory bowel disease.
- Dysentery is diarrhoea with visible blood and mucus and points to invasive organisms.
- The most immediate danger in acute diarrhoea is dehydration and electrolyte loss.
- Oral rehydration solution is the cornerstone of treatment for most acute diarrhoea.
- Cholera causes profuse rice-water stools and can be confirmed by darting motility on hanging-drop microscopy.
- Stool microscopy identifies parasitic causes such as Entamoeba histolytica and Giardia lamblia.
- Amoebic dysentery is treated with metronidazole followed by a luminal agent to clear cysts.
- Most acute watery diarrhoea is self-limiting and does not require antibiotics.
- Antibiotics are reserved for specific bacterial causes, dysentery or severe systemic illness.
- Chronic diarrhoea warrants investigation for malabsorption, coeliac disease and inflammatory bowel disease.
- Crohn disease and ulcerative colitis differ in distribution, depth of inflammation and complications.
- Ulcerative colitis is a continuous mucosal disease of the colon, while Crohn disease is patchy and transmural.
- Inflammatory bowel disease is managed with aminosalicylates, steroids, immunomodulators and biologics.
- Zinc supplementation alongside oral rehydration reduces the duration and severity of childhood diarrhoea.
Diarrhoea essentials
- **Acute versus chronic:** Acute is usually infective; chronic suggests malabsorption or inflammatory bowel disease.
- **First priority:** Assess and correct dehydration; oral rehydration solution is the cornerstone.
- **Stool clues:** Rice-water stool in cholera; blood and mucus in dysentery; parasites on microscopy.
- **Inflammatory bowel disease:** Ulcerative colitis is continuous and mucosal; Crohn is patchy and transmural.
NMC competencies in this chapter
- **IM16.1:** Aetiology of acute and chronic diarrhoea
- **IM16.2:** Acute systemic consequences and fluid balance
- **IM16.6:** Diarrhoea versus dysentery
- **IM16.9:** Microscopic identification of parasitic causes
- **IM16.13:** Pharmacotherapy for parasitic diarrhoea
- **IM16.14:** Pharmacotherapy for bacterial and viral diarrhoea
- **IM16.15:** Crohn disease versus ulcerative colitis
- **IM16.16:** Pharmacotherapy including immunotherapy for inflammatory bowel disease
Frequently Asked Questions
What is the mainstay of treatment for acute diarrhoea?
Oral rehydration solution to replace fluid and electrolyte losses is the mainstay, since most acute watery diarrhoea is self-limiting and does not need antibiotics.
When are antibiotics indicated in diarrhoea?
Antibiotics are reserved for specific bacterial causes, dysentery, cholera and severe systemic illness, rather than for routine acute watery diarrhoea.
How do Crohn disease and ulcerative colitis differ?
Ulcerative colitis causes continuous mucosal inflammation confined to the colon, while Crohn disease causes patchy transmural inflammation anywhere from mouth to anus.
How does this chapter help for NEET-PG?
Stool findings, oral rehydration, the treatment of amoebiasis and the Crohn versus ulcerative colitis contrast are common exam themes that map directly to questions.
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