Inflammatory bowel disease (IBD) is the term given to inflammatory conditions that affect the GI tract. There are 2 main conditions: to be considered ulcerative colitis and Crohn’s disease.
Let’s discuss ulcerative colitis and Crohn’s independently and then we will take a look at some of the key distinctions between the two diseases:
🏘 Epidemiology
UC is most prevalent within Caucasian populations. There are 2 distinct age groups that are affected: 15-25 years old and 55-65 years old. Males and females tend to be affected equally.
Pathophysiology
At this stage the exact aetiology is yet to be determined. It is theorised that both genetics and environmental triggers are at play.
⚠️ Risk factors
HLA-B27
Caucasian (Ashkenazi Jews in particular)
Family history
Smoking cessation
😷 Presentation
It tends to follow a course of remission followed by relapse.
The telltale characteristics are:
- ⭐️ Bloody stool is a cardinal sign found in 90% of cases. Patients with bloody diarrhoea usually have proximal colon involvement and have features of dehydration and electrolyte imbalance.
- ⭐️ Mucus discharge occurs due to the ulceration (despite goblet cell reduction)
- ⭐️ Pseudopolyps may form due to cycles of ulceration and healing which causes the tissue to be raised.
- Diffuse continual mucosal inflammation of the large bowel. Starting in the rectum → proximally and it can affect the entire large intestine, and in certain cases the distal ileum even (backwash ileitis if it renders the ileocaecal valve incompetent). It only affects the mucosa, this also differs when compared to Crohn’s.
- Increased frequency and urgency of defecation
- Chronic nocturnal diarrhoea
Extra-intestinal manifestations
- Skin - erythema nodosum (especially on shins) and pyoderma gangrenosum
- MSK - enteropathic arthritis (arthritis due to IBD), clubbing.
- Eyes - episcleritis, anterior uveitis, iritis.
- Hepatobiliary - primary sclerosing cholangitis.
🔢 Classification
The severity of an exacerbation is classified using the Truelove and Witt criteria:
Criteria | Mild | Moderate | Severe |
Bowel movements
daily | <4 | 4-6 | >6 |
Blood in stool | Minimal | Mild | Visible |
Pyrexia | No | No | Yes |
Pulse >90bpm | No | No | Yes |
Anaemia | No | No | Yes |
ESR (mm/hour) | <30 | 30 | >30 |
- Histology
- Non-granulomatous inflammation
- Goblet cell hypoplasia - leading to decrease in mucous secretion.
- Crypt abscesses - an accumulation of inflammatory cells within crpyts of the GI tract causing damage to cells and glandular function.
CRP is used instead of ESR in practice nowadays.
The Montreal score may be used to quantify the extent (proctitis → pancolitis) and the Mayo score may be used to quantify the severity of the disease.
🔍 Investigations
- 🏆 Colonscopy with biopsy is the gold standard.
- 🏆 Flexible sigmoidoscopy is preferred in severe UC due to risk of perforation with colonoscopy.
- Abdominal X-ray/CT may be used to assess for toxic megacolon or perforation in exacerbations. Some other features of AXR in acute exacerbations are:
- Mural thickening
- Lead-pipe colon
- Barium enema is also good and may show loss of haustrations.
CRP ⬆️ WCC ⬆️ Anaemia TGN levels (which tells us about the levels of metabolites in the blood, i.e. is the drug getting to where it needs to be at high enough concentrations).
🧰 Management
💊 Medical management
Inducing remission (in cases of exacerbation):
Mild-to-moderate ulcerative colitis:
- Proctitis
- Topical (rectal) aminosalicylate: for distal colitis rectal mesalazine has been shown to be superior to rectal steroids and oral aminosalicylates
- If remission is not achieved within 4 weeks, add an oral aminosalicylate
- If remission still not achieved add topical or oral corticosteroid
- Proctosigmoiditis and left-sided ulcerative colitis:
- Topical (rectal) aminosalicylate
- If remission is not achieved within 4 weeks, add a high-dose oral aminosalicylate OR switch to a high-dose oral aminosalicylate + a topical corticosteroid.
- if remission still not achieved stop topical treatments and offer an oral aminosalicylate and an oral corticosteroid.
- Extensive disease:
- Topical (rectal) aminosalicylate and a high-dose oral aminosalicylate:
- If remission is not achieved within 4 weeks, stop topical treatments and offer a high-dose oral aminosalicylate and an oral corticosteroid.
Severe colitis:
- IV steroids are given first-line
- IV ciclosporin may be used if steroid are contraindicated
- If after 72 hours there has been no improvement, consider adding intravenous ciclosporin to intravenous corticosteroids or consider surgery.
To maintain remission:
Following a mild-to-moderate ulcerative colitis flare:
- Proctitis and proctosigmoiditis
- Topical aminosalicylate alone (daily or intermittent) OR
- Oral aminosalicylate + a topical aminosalicylate (daily or intermittent) OR
- Oral aminosalicylate by itself: this may not be effective as the other two options
- Left-sided and extensive ulcerative colitis:
- Low maintenance dose of an oral aminosalicylate
Following a severe relapse or >2 exacerbations in the past year:
- Oral azathioprine or oral mercaptopurine
Fluid resuscitation, nutritional support, and prophylactic heparin should be given as IBD flares induce a thrombotic state.
Severity | 🥇First line | 🥈Second line |
Mild - moderate | 🥇 Aminosalicylate - mesalazine (oral/rectal) | Corticosteroids - oral prednisolone |
Severe | 🏆 IV corticosteroids (100mg QDS) | Infliximab is now preferred
IV ciclosporin was used |
- Aminosalicylates (such as mesalazine or sulfasalazine) are preferred. Mesalazine is also known as octasa.
- Azathioprine
- Mercaptopurine
- Refractory to medical management
- Toxic megacolon
- Perforation
🏆 It usually involves resection of the bowel (subtotal colectomy) + stoma. Total proctocolectomy is curative. However, a subtotal colectomy is usually done first with an ileo-rectal anastomosis (IRA)/panproctocolectomy with an ileo-pouch anal anastamosis (IPAA).
⛔ Complications
- Toxic megacolon
- CRC
- Osteoporosis due to prolonged corticosteroid use.
- Pouchitis of IPAA
🏘 Epidemiology
Crohn’s affects about 150/100,000 in the UK.
Once again it has a bimodal peak between 15 - 30 years old and then 60 - 80 years old once again.
Pathophysiology
Once again the aetiology is unknown. There seems to be familial linkage once again.
⚠️ Risk factors
- Family history
- Smoking
- Caucasian ethnicity + Ashkenazi Jews
- Genetics
😷 Presentation
It also tends to follow a course of remission followed by relapse.
- Episodic abdominal pain + diarrhoea (usually non-bloody)
- Weight loss is more noticeable due to malabsorption
- Terminal ileum is most commonly affected but it can affect any part of the GI tract (mouth [aphthous ulcers] → anus [perianal disease]).
- Transmural inflammation which produces a cobblestone appearance due to the fissures.
- Skip lesions
- Rose-thorn ulcer
- Fat-wrapping is something specific to Crohn’s.
- Kantor string sign - may be seen on a barium study. This is a long segment of narrowed terminal ileum in a 'string like' configuration in keeping with a long stricture segment.
- Histology
- Non-casseating granulomas
- Goblet cell hyperplasia
Extra-intestinal manifestations
- Skin - erythema nodosum (especially on shins).
- MSK - enteropathic arthritis (arthritis due to IBD), clubbing.
- Eyes - episcleritis, anterior uveitis, iritis.
- Hepatobiliary - gallstones and cholangiocarcinoma
- Renal - renal stones
🔢 Classification
We can classify severity using using the Montreal Score which looks at 3 parameters:
- Age at diagnosis:
- A1 - <16 years
- A2 - 17 - 40 years
- A3 - >40 years
- Location:
- L1 - ileal
- L2 - colonic
- L3 - ileocolonic
- L4 - isolated upper disease
- Behaviour:
- B1 - non-stricturing and non-penetrating
- B2 - stricturing
- B3 - penetrating
🔍 Investigations
Faecal calprotectin
Microscopy + culture of stool sample should be done too
🧰 Management
💊 Medical management
Fluid resuscitation, nutritional support, and prophylactic heparin + anti-embolic stockings should be given as IBD flares induce a thrombotic state.
🥇 Corticosteroid therapy is first line to induce remission.
🥈 Immunosuppressive agents (such as mesalazine or azathioprine)
🥉 Biological agents (such as infliximab or adalimumab) may be tried if needed.
Inducing remission (in-depth guidelines)
- Glucocorticoids (oral, topical or intravenous) are generally used to induce remission.
- IV hydrocortisone
- Budesonide is an alternative in certain patients.
- Enteral feeding with an elemental diet may be used in addition to or instead of other measures to induce remission, particularly if there is concern regarding the side-effects of steroids (for example in young children). An elemental diet is a liquid meal replacement diet that offers a complete nutritional profile broken down into its most “elemental” form.
- 5-ASA drugs (e.g. mesalazine) are used second-line to glucocorticoids but are not as effective.
- Azathioprine or mercaptopurine* may be used as an add-on medication to induce remission but is not used as monotherapy. Methotrexate is an alternative to azathioprine.
- Assess thiopurine methyltransferase (TPMT) activity before offering azathioprine or mercaptopurine. The TPMT enzyme "turns off" thiopurine drugs by breaking them down into inactive, nontoxic compounds.
- Infliximab is useful in refractory disease and fistulating Crohn's. Patients typically continue on azathioprine or methotrexate.
- Metronidazole is often used for isolated peri-anal disease.
- 🥇 Azathioprine monotherapy first-line or mercaptopurine.
- TPMT activity should be assessed before starting
- 🥈 Methotrexate is used second-line
Smoking cessation is needed where necessary.
📷 Colonoscopic surveillance is needed in patients suffering for more than 10 years with >1 segment of the bowel affected as they are at increased risk of CRC.
- Refractory to medical management
- Stricturing
- Perforation
Operations follow a bowel-sparing approach to prevent short gut syndrome later on.
There are a variety of surgeries that may be performed:
- Ilocaecal resection - removal of terminal ileum. It is indicated if there is stricturing terminal ileum disease.
- Small/large bowel resection - may be segmented.
- Peri-anal abscess drainage + other surgeries for peri-anal disease.
- Stricturoplasty - division of a stricture that is causing an obstruction
⛔ Complications
- Fistulae - 10-15% of patients show this as the first sign. This is an inflammatory tract or connection between the anal canal and the perianal skin. MRI is the investigation of choice for suspected perianal fistulae - can be used to determine if there (is an abscess and if the fistula is simple (low fistula) or complex (high fistula that passes through or above muscle layers).
- Patients with symptomatic perianal fistulae are usually given oral metronidazole.
- Anti-TNF agents such as infliximab may also be effective in closing and maintaining closure of perianal fistulas.
- A draining seton is used for complex fistulae
- Peri-anal abscesses - these require incision and drainage combined with antibiotic therapy.
- A draining seton may also be placed if a tract is identified
- Strictures
- Malignancy
- Delayed growth in children
- Osteoporosis
- Gallstones (due to impaired bile salt reabsorption in the terminal ileum)
- Renal stones - due to malabsorption of fat in the small bowel, causing calcium to remain in the lumen, resulting in hyperoxaluria (oxalate is normally bound to calcium and excreted in stool but instead accumulates in the urinary tract)
[DO QUESTIONS ON QUESMED AND ADD IN COMPLICATIONS SUCH AS PSC AND CHOLANGIOCARCINOMA]