Small Bowel Conditions

Coeliac disease

This is a condition characterised by T cell-mediated damage of the small bowel villi due to gluten exposure, which leads to malabsorption.

Gluten is found in wheat and grains and causes reduced mucosal absorption in the distal duodenum +/- proximal jejunum.

It is associated with HLA-DQ2 and HLA-DQ8, and onset has a bimodal prevalence pattern, presenting in childhood and again between 50–60 years.

If untreated, it can lead to T cell lymphoma of the small intestine.

Symptoms

Diarrhoea, bloating, abdominal pain

Steatorrhea, weight loss

Fatigue and failure to thrive

Hyposplenism

Anaemia secondary to iron, folate and vitamin B12 deficiency

Osteoporosis, osteomalacia

Associated conditions

Dermatitis herpetiformis, due to IgA deposition in dermis

Autoimmune thyroid disease

Type 1 diabetes

Irritable bowel syndrome

Lactose intolerance

Key tests

1st line is to check tissue transglutaminase (TTG) IgA and endomyseal antibody (IgA)

Patients should be on a gluten-containing diet for at least 6 weeks before the test

You should look at TTG levels in relation to overall IgA levels, as if the patient is deficient in IgA, then this can lead to a false negative result

If IgA deficient, repeat test for TTG with the IgG isoform and check HLA-DQ2 status

If the above is positive, definitive test is a duodenal biopsy. This shows villous atrophy, hyperplasia of the crypts and infiltration with lymphocytes.

Management

Dietary adjustment with gluten free diet

Pneumococcal vaccination every 5 years, as patients display hyposplenism

Whipple disease

This is a rare disease causing GI malabsorption, which occurs due to the bacteria Tropheryma Whippelli

These bacteria infect macrophages which compress lacteals resulting in fat malabsorption

Symptoms

Starts with arthralgia (pain of peripheral joints)

GI symptoms – Abdominal pain, weight loss, steatorrhea

Systemic symptoms – fever, sweats, cough

Skin symptoms – Photosensitivity and hyperpigmentation

Can involve CNS (dementia, seizures) and the heart (pericarditis)

Key tests

Jejunum biopsy – shows macrophages containing Periodic acid-Schiff (PAS) granules

Management

Antibiotics (e.g. Ceftriaxone followed by co-trimoxazole)

Abetalipoproteinemia

This is an autosomal recessive disorder due to a genetic mutation occurs in a transporter which leads to deficiency of apolipoprotein B-48 and B-100.

These apolipoproteins are needed for the synthesis of chylomicrons and VLDLs.

These are required to absorb fats. Therefore, this condition interferes with the normal absorption of fat and fat-soluble vitamins.

Symptoms

Fat malabsorption – steatorrhea (pale stools), failure to thrive, weight loss

Vitamin E (fat soluble) deficiency – gives cerebellar ataxia and peripheral neuropathy

Key tests

Blood test shows hypocholesterolaemia

Blood film shows acanthocytosis (spiked RBCs)

Management

Vitamin E supplements and high fat diet

Irritable Bowel Syndrome

This is a multi-factorial condition associated with abdominal symptoms.

Patients may have chronic symptoms but blood tests and imaging will be normal.

Symptoms should be present for about 6 months to receive a diagnosis.

Symptoms

Abdominal pain, which is often relieved by defecation

Bloating – this leads to abdominal distention, usually gets worse after eating and can be triggered by particular foods

Change in bowel habit – either diarrhoea or constipation depending on the subtype

Management

1st line involves treating the most predominant symptom, e.g., pain with antispasmodic medication, constipation with laxatives or diarrhoea with loperamide

Other options include low dose amitriptyline or SSRIs

If no response to medication, can offer CBT or psychological therapy

Dietary advice includes avoiding trigger foods and having low FODMAP diet. These are carbohydrates which are poorly absorbed in the small intestine

Small Bowel Obstruction

This is an obstruction in the small intestine, preventing the passage of food/liquid through gut tube.

Causes

Adhesions – these are bands of fibrous tissue that form between organs and tissues, often due to previous abdominal surgery

Volvulus – this is the twisting of bowel with its mesentery, usually occurring in the sigmoid bowel (elderly) and caecal region (young adult)

Intussusception – this is when one part of the bowel slides into the next segment (like a collapsible telescope), which is more common in small children

Tumours – these can cause compression intramurally or from extrinsic compression

Strictures – these occur secondary to conditions like Crohn’s disease

Hernias – most are asymptomatic, but a few can result in bowel obstruction

Symptoms

Abdominal pain and distension

Unpredictable early vomiting

Constipation

“Tinkling bowel sounds”

Key tests

Abdominal X-ray and erect CXR are quick

CT scan is the best to establish the cause of obstruction and check for bowel perforation

Management

“Drip and suck” – keep the patient nil by mouth.

Insert nasogastric tube to drain the stomach contents and give IV fluids to rehydrate and correct electrolytes

Anti-emetics (not prokinetic metoclopramide)

If it is unresolving, secondary to strictures/tumours or there is evidence of bowel ischaemia/perforation, then surgery may be required

Carcinoid Tumours

This refers to a proliferation of enterochromaffin cells (neural crest origin), which usually occurs in the small bowel.

The tumour cells contain neurosecretory granules and often secrete 5-HT.

Serotonin is released into portal circulation and excreted in the urine as 5-HIAA.

These primary tumour sites can cause complications such as bowel obstruction, appendicitis and intussusception.

The main problem occurs when the tumour metastasises to the liver.

This allows 5-HT to enter the systemic circulation. This leads to carcinoid syndrome, which is often triggered by alcohol and emotional stress stimulating 5-HT release.

Symptoms

Flushing of the face, diarrhoea and bronchospasm

Hypotension

Right sided heart valve fibrosis – tricuspid regurgitation, pulmonary stenosis

Paraneoplastic syndromes due to hormone release e.g., ACTH, insulin, TSH

Key tests

Raised urinary 5-HIAA, raised blood chromogranin A (a neuroendocrine marker)

CT abdomen and pelvis to visualise the tumour and liver metastases

Management

Octreotide counters the peripheral effects of carcinoid syndrome

Surgical management involves resection of the tumour