Brief, factual descriptions of conditions that may be discussed during a gastroenterology consultation.
Hong Kong gastroenterology and hepatology information from Dr Paul Ng. Consultations in Central and Tsim Sha Tsui are by appointment; assessment and care are individual.
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Bowel
Bowel polyps / colonic polyps
Colonic polyps are growths on the inner surface of the large bowel and usually cause no symptoms. Adenomas and some serrated lesions can slowly develop into cancer, whereas other polyp types have little or no cancer potential. Colonoscopy allows a clinician to remove many polyps and send them for laboratory examination, which establishes the type more reliably than appearance alone.
The colonoscopy report records how well the bowel was prepared and seen, whether the examination reached the intended area, and whether a polyp was removed completely. Pathology may identify an adenoma, a serrated lesion or a non-neoplastic growth, each with different implications. A larger or more numerous group of precancerous polyps can alter the timing of follow-up, but intervals also depend on examination quality and personal risk. Keep the pathology and procedure reports together for review; recommendations may change if an examination was incomplete or removal was uncertain. Some larger lesions require removal in stages or by a specialist technique, making the endoscopist’s documentation especially important. Screening recommendations for relatives, if relevant, depend on the exact pathology and family history and should be discussed rather than inferred from the word “polyp.” The exact pathology wording matters: “precancerous” does not mean that a polyp is already cancer, and removal is an important prevention opportunity. A personal history of polyps or colorectal cancer in close relatives may affect the recommended follow-up discussion.
Understanding adenomas
Tubular and villous patterns
An adenoma is a gland-forming polyp with the potential to develop into cancer over time. Under a microscope, tubular adenomas are mainly made up of tube-shaped glands; villous adenomas have more finger-like projections, while tubulovillous adenomas contain both patterns. These terms describe tissue architecture, not the size of the polyp. Villous features are associated with a higher chance of advanced changes, but the pattern alone cannot predict an individual outcome. The type is confirmed by pathology after removal, not by appearance alone.
Size, dysplasia and other factors
A larger adenoma, particularly one measuring 10 mm or more, is generally more concerning than a smaller one. Dysplasia describes how abnormal its cells appear: low-grade changes are less advanced; high-grade dysplasia is a more advanced precancerous change, but is not the same as invasive cancer. Risk and follow-up also depend on the number of adenomas, whether removal was complete, bowel-preparation and examination quality, previous polyp findings, and relevant personal or family history. Serrated polyps follow a different classification.
The pathology and colonoscopy reports should be reviewed together. No single feature determines a surveillance interval for everyone; your clinician will explain whether and when another examination is appropriate.
The pathology, number, size and location of polyps are considered together with whether removal was complete, bowel preparation and visibility, and personal or family history. These details determine whether and when another colonoscopy may be useful; there is no single interval suitable for every finding. Blood in stool or a new bowel change should be assessed rather than assumed to be caused by a polyp.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
Diverticular disease / diverticulosis and diverticulitis
Diverticulosis means small pouches in the bowel wall, usually the colon. Many cause no symptoms. Diverticulitis is inflammation involving a pouch; diverticular bleeding is a different complication and can occur without pain.
Diverticula are not bowel polyps and are not themselves cancer. Abdominal pain has many possible causes, so finding diverticula does not prove they explain symptoms. Suspected acute diverticulitis may need examination, blood tests and imaging such as CT. Antibiotics and hospital treatment depend on severity, complications and individual risk; they are not automatic for every uncomplicated episode. Colonoscopy may be considered after recovery when appropriate, rather than routinely during acute inflammation. Long-term dietary advice is individual; a blanket ban on nuts and seeds is not generally required.
For discussion in consultation
Seek urgent care for severe or worsening abdominal pain, fever with significant illness, persistent vomiting, or substantial rectal bleeding. Fainting or bleeding with marked weakness warrants emergency assessment.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
Ulcerative colitis is a chronic inflammatory bowel disease that affects the lining of the large intestine, usually beginning in the rectum and extending continuously for a variable distance. It can cause diarrhoea, blood or mucus in stool, urgency and abdominal discomfort, with periods of greater activity and remission. The pattern and severity differ between people.
Ulcerative colitis usually affects the rectum and colon continuously, although the length of involved bowel varies. Endoscopy and biopsies help confirm the pattern and extent; symptom improvement does not by itself show whether inflammation is controlled, so assessment may also use stool or blood markers and consider colorectal surveillance over time.
For discussion in consultation
Assessment brings together symptoms, examination, blood and stool tests, and endoscopy with biopsies when appropriate. Clinicians consider the extent and activity of inflammation, possible infection, nutrition and complications; the diagnosis is distinguished from Crohn disease and other causes of colitis. Long-term review may include treatment response and colorectal cancer risk according to disease history.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
Crohn disease is a chronic inflammatory bowel disease that can affect any part of the digestive tract, most often the small bowel and colon. Inflammation may involve deeper bowel layers and occur in separated areas. Symptoms can include abdominal pain, diarrhoea, fatigue and weight loss; complications may include narrowing, abscesses or abnormal connections between organs.
Crohn disease can affect different digestive-tract sites and may cause inflammation through the bowel wall, sometimes with areas of normal tissue between affected segments. Endoscopy, small-bowel imaging, laboratory markers and nutritional review can answer different questions; narrowing, fistulas and abscesses are complications clinicians may assess for when appropriate.
For discussion in consultation
Evaluation considers the symptom pattern, blood and stool tests, endoscopy with biopsies and small-bowel imaging as indicated. Clinicians look for the location and activity of inflammation, nutritional effects and complications, while excluding infections and other explanations. Monitoring depends on the disease course and may use symptoms, laboratory markers, endoscopy or imaging rather than symptoms alone.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
Microscopic colitis is inflammation of the colon that usually causes persistent watery, non-bloody diarrhoea. Urgency, night-time stools or leakage may occur. The bowel can look normal or almost normal during colonoscopy; the changes are seen in biopsies under a microscope.
The main forms are collagenous colitis and lymphocytic colitis. It is not the same as IBS, ulcerative colitis or Crohn disease, although symptoms may overlap. Assessment reviews the diarrhoea pattern, hydration, medicines and other causes such as infection, coeliac disease or bile acid diarrhoea. When suspected, colonoscopy with biopsies from different parts of the colon helps establish the diagnosis; a normal visual examination alone does not exclude it. Some medicines are associated with microscopic colitis, but association does not prove that a medicine caused an individual case. Do not stop prescribed treatment without discussing it. Care may include a clinician-led medicine review and prescribed treatment such as budesonide, according to symptoms, biopsy findings and individual risk.
For discussion in consultation
Persistent watery diarrhoea warrants review rather than assuming it is IBS. Blood in the stool, unexplained weight loss or worsening symptoms need prompt assessment. Severe dehydration, fainting or severe abdominal pain requires urgent care.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
Celiac disease is an immune-mediated condition triggered by gluten in genetically susceptible people. It can injure the small-intestinal lining and interfere with nutrient absorption, but symptoms vary and may include diarrhoea, bloating, abdominal discomfort, anaemia or no obvious digestive symptoms. It is distinct from wheat allergy and non-celiac gluten sensitivity.
Celiac-specific antibody testing and small-bowel biopsies are interpreted together with symptoms and nutritional findings. Starting a gluten-free diet before evaluation can make tests less informative, so diagnostic testing is planned and interpreted in context; after diagnosis, follow-up may consider symptom course, blood tests and nutrient status.
For discussion in consultation
Assessment commonly includes celiac-specific blood tests and, for many adults, upper endoscopy with small-bowel biopsies. Testing can be affected if gluten has already been removed from the diet, so results and preparation require clinical interpretation. Clinicians also consider nutritional deficiencies, associated conditions and whether the findings fit together; blood tests alone do not establish every diagnosis.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
SIBO describes an excessive number or altered pattern of bacteria in the small intestine, where bacterial levels are normally lower than in the colon. It can be associated with bloating, gas, abdominal discomfort, diarrhoea and, in some cases, problems absorbing nutrients. These complaints are common and have many possible causes, so they do not prove SIBO.
SIBO can develop secondary to various gastrointestinal conditions, including impaired gut movement or altered bowel anatomy after surgery, and may be associated with medication use. Assessment should review overall health, medical and surgical history, nutrition and all regular medicines, rather than focusing only on SIBO or a breath-test result. Addressing contributing factors is part of care. Do not stop or change prescribed medicines without discussing this with your clinician. Breath testing commonly measures hydrogen and methane after a prepared drink; results depend on the test method, preparation and how quickly material moves through the intestine. A positive result is not automatically proof that bacteria explain every symptom, and a negative test may not exclude every relevant problem. Clinicians look for reasons bacterial overgrowth might occur, such as altered anatomy or impaired movement, and may consider other common explanations for gas and diarrhoea. Repeated antibiotics without a clear indication can cause side effects and resistance, so testing and treatment are best interpreted in context. A clinician can explain the preparation instructions and what the chosen test can or cannot establish before it is done. Persistent diarrhoea, unintended weight loss or signs of nutritional deficiency deserve broader evaluation rather than assuming SIBO is the only cause. If symptoms return after treatment, review of the original reason for testing and possible underlying motility or anatomical factors may be more useful than repeating antibiotics automatically. Mention persistent diarrhoea, weight loss or nutritional concerns during follow-up.
For discussion in consultation
A clinician may consider prior intestinal surgery, altered gut anatomy or movement, and other risk factors before deciding whether testing is useful. Breath tests measure gases after a test sugar is taken; preparation and intestinal transit can affect results, and false positive or negative findings occur. Treatment decisions should not rely on symptoms or a single test in isolation.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
Reduced activity of the enzyme lactase can leave lactose, the sugar in milk, incompletely digested. It can then cause gas, bloating, cramps or diarrhoea. Lactose intolerance is not the same as a milk-protein allergy.
Symptoms depend partly on the amount eaten and individual tolerance; not everyone needs to avoid all dairy products. Lactose malabsorption can occur without symptoms, and intolerance may be temporary or secondary to small-bowel conditions such as coeliac disease. Assessment may use a supervised reduction and reintroduction of lactose, or a hydrogen breath test when appropriate, interpreted alongside symptoms. Avoid unnecessary long-term dietary restriction. Lactose-free options, individual portions or lactase supplements may help some people, while maintaining adequate calcium and vitamin D.
For discussion in consultation
Review persistent symptoms and nutrition with a clinician or dietitian. Blood in the stool, weight loss or ongoing diarrhoea should not simply be attributed to lactose intolerance. Suspected allergy needs a different assessment.
Excess bile acids reaching the colon can cause watery diarrhoea and urgency. Bile acid diarrhoea can occur on its own or be associated with disease or surgery affecting the ileum, and sometimes after gallbladder removal.
Not all chronic diarrhoea is IBS, and not all diarrhoea after gallbladder surgery is caused by bile acids. Assessment considers medicines, bowel and surgical history, nutrition and alternative causes. Tests such as SeHCAT or fasting serum C4 may support diagnosis where available; availability varies and this page does not imply these tests are offered at the clinic. Treatment may include a prescribed bile acid sequestrant and individual dietary advice. These medicines can affect absorption of other drugs, so dosing and timing need professional review rather than self-treatment.
For discussion in consultation
Persistent watery diarrhoea warrants assessment, including consideration of dehydration and other conditions. Seek prompt care for blood in the stool, unexplained weight loss or significant dehydration; do not change prescribed medicines without advice.
Haemorrhoids are vascular cushions in the anal canal that can become symptomatic. Internal haemorrhoids may cause painless bright-red bleeding or prolapse, while external haemorrhoids can cause discomfort, swelling or a tender lump. Rectal bleeding should not automatically be attributed to haemorrhoids because other conditions can cause it.
Haemorrhoids are common, but visible bleeding can also arise from other colorectal conditions and requires interpretation in the context of age, history and examination. Anoscopy can help identify internal haemorrhoids, while persistent or atypical bleeding may prompt additional evaluation; treatment choices depend on anatomy and symptom burden.
For discussion in consultation
Assessment considers bleeding, pain, bowel habits, examination findings and relevant medical history; examination may include inspection and anoscopy. The clinician considers whether additional evaluation is appropriate, especially when bleeding is persistent or the pattern is not typical. Management options vary with symptom severity and haemorrhoid type, and procedures are considered only in context.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
An anal fissure is a small tear in the lining of the anal canal. It can cause sharp pain during a bowel movement that continues afterwards, sometimes with a small amount of bright red blood on the paper or stool. Both hard stools and frequent diarrhoea can contribute.
A fissure is different from haemorrhoids, and neither should be assumed to explain all anal pain or rectal bleeding. Assessment usually considers the symptom pattern and a gentle examination; persistent, multiple or unusually located fissures may need investigation for other causes, including Crohn disease. Initial care often aims for soft, formed stools, avoiding straining and warm baths. Persistent fissures may need prescription ointment or specialist treatment. Surgery is not automatic: expected benefit and risks, including effects on continence, require individual discussion. Haemorrhoid rubber-band ligation is not a treatment for an anal fissure.
For discussion in consultation
Seek review for recurring pain, a tear that does not heal or persistent bleeding. Fever with anal swelling or constant worsening pain may indicate another problem, such as an abscess, and needs urgent assessment. Heavy bleeding, fainting or marked weakness warrants emergency care.
Radiation proctitis describes irritation or injury of the rectum after radiation treatment to the pelvis. It may occur during or soon after treatment, or appear months to years later. Symptoms can include urgency, diarrhoea, rectal discomfort or bleeding. These symptoms may have other causes, and bleeding should not automatically be attributed to prior radiation.
Rectal bleeding after pelvic radiotherapy can have several explanations, so a previous radiation history does not by itself establish radiation proctitis. Assessment may need to account for the original cancer, radiation field and timing, other treatments and medicines, and possible alternative causes. Endoscopy or other tests are selected to answer a clinical question and should be coordinated with the oncology history. Heavy bleeding, fainting, severe pain, fever or black stools warrants urgent assessment.
For discussion in consultation
A clinician reviews the type and timing of radiation, symptoms, medicines and other health history. Examination, blood tests or endoscopy may be considered to assess the rectum and exclude other explanations; the best evaluation depends on the person’s cancer and treatment history. Heavy bleeding, black stools, fainting, severe pain or fever needs urgent medical care.
Related procedure information
These links are general information, not a recommendation for an examination or treatment.
These summaries are for general information only. They cannot establish a diagnosis or determine whether you need tests, surveillance or treatment. Your own results, risks and options must be reviewed in an actual consultation with a qualified clinician. Do not start, stop or change treatment based on this page.
References are provided for background reading; they do not replace a consultation.
Questions about a finding on your scan, blood test or endoscopy report? Discuss the full report and your history in a consultation.
About this information
This is general educational information, not a diagnosis, a personalised recommendation or consent for a procedure. Whether to investigate or treat, the alternatives (including no procedure), benefits and risks require individual clinical assessment and discussion.