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Urology

Assess clinical state. Rehydration is key. Altered bowel habit may suggest colorectal cancer. Causes are mainly infective, ischaemic and malignant and context will help

About

Increased stool output > 200 g/day
Increased stool fluid content and frequency
Chronic diarrhoea when lasts > 3 weeks
Steatorrhoea is > 7g fat per day in stools on a high-fat diet

Clinical

Watery stools, mucus, abdominal cramping pain

Causes

Cause	Clinical Features	Investigations/Tests	Management
Bacterial Gastroenteritis (e.g., Salmonella, Shigella, Campylobacter, E. coli)	Watery or bloody diarrhoea, abdominal pain, fever, nausea, vomiting	Stool culture, PCR, blood tests (WBC, CRP), stool microscopy	Oral/IV rehydration, antibiotics in severe cases (e.g., Ciprofloxacin for Campylobacter), supportive care
Viral Gastroenteritis (e.g., Norovirus, Rotavirus, Adenovirus)	Watery diarrhoea, nausea, vomiting, fever, abdominal cramps	Stool PCR, rapid antigen testing	Rehydration therapy, supportive care, hand hygiene to prevent spread
Parasitic Infections (e.g., Giardia, Entamoeba histolytica, Cryptosporidium)	Watery or greasy diarrhoea, abdominal cramps, bloating, weight loss	Stool microscopy, antigen tests, PCR for specific parasites	Metronidazole for Giardia and Entamoeba; Nitazoxanide for Cryptosporidium
Clostridium difficile (C. diff) (Common in immunosuppressed or after antibiotic use)	Watery diarrhoea, abdominal pain, fever, recent antibiotic use	Stool toxin assay, PCR, endoscopy in severe cases	Stop offending antibiotics, start oral Vancomycin or Fidaxomicin
Inflammatory Bowel Disease (IBD) (Crohn’s disease, Ulcerative colitis)	Chronic diarrhoea, abdominal pain, bloody stools, weight loss	Colonoscopy with biopsy, stool calprotectin, CRP, ESR	Aminosalicylates, corticosteroids, immunosuppressants, biologics (e.g., Infliximab)
Food Poisoning (e.g., Staphylococcus aureus, Bacillus cereus)	Acute onset diarrhoea, vomiting, abdominal cramps, after ingestion of contaminated food	Clinical diagnosis based on history, stool culture for confirmation	Supportive care, rehydration, self-limiting in most cases
Lactose Intolerance	Bloating, gas, diarrhoea after consumption of dairy products	Lactose hydrogen breath test, stool pH test	Dietary modification (avoid lactose-containing foods), lactase supplements
Coeliac Disease	Chronic diarrhoea, weight loss, bloating, malabsorption, anaemia	Serology (anti-tTG, anti-EMA), small bowel biopsy	Gluten-free diet, nutritional supplementation
Medications (e.g., Antibiotics, Metformin, Laxatives, Chemotherapy)	Diarrhea after starting a new medication	Medication history, stool tests to exclude infection	Discontinue or adjust medication, rehydration, probiotics
HIV-related Diarrhea (e.g., Cryptosporidium, CMV, Microsporidia)	Chronic diarrhoea, weight loss, fever, in immunosuppressed patients	Stool microscopy, PCR for pathogens, colonoscopy with biopsy	Treat underlying infection (e.g., Nitazoxanide for Cryptosporidium), antiretroviral therapy (ART)
Graft-vs-Host Disease (GVHD) (Post-transplant)	Chronic diarrhoea, abdominal pain, after allogeneic transplant	Colonoscopy with biopsy, blood tests for liver and renal function	Immunosuppressive therapy (e.g., corticosteroids), symptomatic treatment
Irritable Bowel Syndrome (IBS) (Diarrhea-predominant)	Chronic intermittent diarrhoea, abdominal cramps, bloating, no weight loss	Exclude other causes (stool tests, colonoscopy), Rome IV criteria for diagnosis	Dietary changes (low FODMAP), antispasmodics, probiotics, fiber supplements
Ischaemic Colitis	Sudden onset lower abdominal pain, bloody diarrhoea, elderly patients or with vascular disease	CT angiography, colonoscopy	Supportive care, antibiotics if necessary, surgery in severe cases

Causes of Bloody Diarrhoea

Cause	Clinical Features	Investigations	Management
Bacterial Gastroenteritis (e.g., Shigella, Campylobacter, Salmonella, E. coli O157:H7)	Acute onset bloody diarrhoea, abdominal pain, fever, dehydration	Stool culture, PCR, fecal microscopy (WBCs)	Oral/IV rehydration, antibiotics in specific cases (Ciprofloxacin for Shigella), avoid antibiotics in E. coli O157:H7 to prevent hemolytic uremic syndrome (HUS)
Entamoeba histolytica (Amoebic Dysentery)	Gradual onset bloody diarrhoea, abdominal cramps, weight loss, fever	Stool microscopy, antigen testing, serology, ultrasound (for liver abscess)	Metronidazole followed by luminal agent (e.g., Paromomycin)
Clostridium difficile Infection (C. diff) (Can be associated with bloody diarrhoea in severe cases)	Watery or bloody diarrhoea, abdominal pain, recent antibiotic use, fever	Stool toxin assay, PCR for C. diff toxin, endoscopy in severe cases	Stop offending antibiotics, Vancomycin or Fidaxomicin for C. diff infection
Inflammatory Bowel Disease (IBD) (Ulcerative Colitis, Crohn's Disease)	Chronic bloody diarrhoea, abdominal pain, weight loss, fever	Colonoscopy with biopsy, stool calprotectin, ESR, CRP	Aminosalicylates, corticosteroids, immunosuppressants, biologics (e.g., Infliximab)
Ischaemic Colitis	Sudden onset abdominal pain, bloody diarrhoea, elderly patients, or those with cardiovascular risk factors	CT angiography, colonoscopy with biopsy	Supportive care, antibiotics if secondary infection, surgery in severe cases
Diverticulitis (Complicated by diverticular bleeding)	Acute onset bloody stools, abdominal pain, fever, in patients with known diverticular disease	CT abdomen, colonoscopy	Antibiotics (e.g., Metronidazole and Ciprofloxacin), surgery if complications arise
Colorectal Cancer	Chronic or intermittent bloody diarrhoea, weight loss, change in bowel habits	Colonoscopy with biopsy, CT abdomen, stool tests (fecal occult blood test, FIT)	Surgical resection, chemotherapy, and/or radiotherapy
Hemorrhagic E. coli (E. coli O157:H7) (Associated with Haemolytic Uremic Syndrome)	Severe bloody diarrhoea, abdominal cramps, low-grade fever, potential HUS (anaemia, renal failure, thrombocytopenia)	Stool culture, PCR for Shiga toxin, blood tests (CBC, renal function)	Supportive care, avoid antibiotics and antimotility agents (to prevent HUS)
Radiation Colitis	Chronic bloody diarrhoea, abdominal pain, in patients with history of pelvic radiation	Colonoscopy with biopsy, imaging for assessment of radiation damage	Supportive care, anti-inflammatory agents, surgery in severe cases
Hemorrhoids/Fissures (Bleeding from rectum with small amounts of blood on stool)	Painless or painful rectal bleeding, bright red blood on stool surface	Proctoscopy, digital rectal exam, anoscopy	Topical treatments (e.g., hydrocortisone), stool softeners, surgical options if severe

Investigations

Assess stool with Bristol stool scale
Stool microscopy and culture, ova cysts and parasites
Clostridioides difficile toxin
Check U&E for dehydration. In children consider Haemolytic uraemic syndrome with certain E coli with bloody diarrhoea
FBC - elevated WCC, Anaemia - Microcytic suggests possibly a colonic malignancy or inflammatory bowel disease. Macrocytosis may be suggested by malabsorption. Dimorphic may suggest both.
LFTS - elevated ALP and Bilirubin with obstruction may cause steatorrhoea

Management

Isolation is generally key if there is any suggestion of an infective cause
ABC, Oral rehydration therapy. IV fluids may be needed in some
Avoid antibiotic especially in those at risk of Haemolytic uraemic syndrome

PLEASE NOTE LEGAL ADVICE: The contents are under continuing development and improvements and may contain errors of omission or fact. Feedback vital and always welcome at drokane at gmail.com. This is not to be used for the assessment, diagnosis or management of patients. It should not be regarded as medical advice. It is only for educational purposes. Please adhere to your local protocols. If you are unwell please seek healthcare advice from your doctor. This does not replace senior or specialist advice. If you do not accept this then please do not use the website. If you need medical advice, please consult a doctor or other appropriate medical professional. If you are a medical professional and you need advice then speak to your senior or colleagues.

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