Small + Large BowelBMA Revision DayAndrew McCorkell

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Small Intestine

MUCOSA

Epithelium & specialisations

Simple columnarEnterocytes - Villi + Microvilli Goblet cells - secrete mucusPaneth cells - Mucosal defense system Enteroendocrine cells

Lamina Propria Loose CT; surrounds the crypts of Leiberkuhn and

supports villi; capillary network and lacteal found in

core of villus; lymphoid tissue increases proximal

to distal

Muscularis mucosae 2 thin layers of smooth muscleInner circular / outer longitudinal

SUBMUCOSA Loose collagenous and elastic CT; lymphoid tissue

may bulge down from lamina propria; Meissner’s

nerve plexuses; forms core of plicae circulares;

Brunner’s glandsMUSCULARISEXTERNA

2 layers of smooth muscleInner circular / outer longitudinalMyenteric nerve plexus

SEROSA/ADVENTITIA

Serosa present except distal duodenum which has

adventitia

3

4

5

Duodenum• 1st part of small intestine

• C – shaped structure

adjacent to head of

pancreas

• Retroperitoneal structure

except for 1st part of

duodenum which is

connected to the

hepatoduodenal ligament

Jejunum• Represents proximal 2/5

• Larger in diameter an thicker

wall than ileum

• Inner mucosa lining of

jejunum is characterised by

numerous prominent folds

that circle the lumen – plicae

circulares

• Less prominent arterial

arcades and longer vasa

recta compared to the ileum

Ileum• Distal 3/5 with thinner

walls

• Less prominent Plicae

Circulares

• Shorter vasa recta

and more arterial

arcades

• Ends at ileo-caecal

junction

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Function

• Absorption

• Enzymatic Digestion

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Clinical Case 1

• 72 yr old gentleman presents with central colicky abdominal pain, constipation, increasing abdominal distension and 2x vomiting episodes.

• PMHx - Stage II R Colon Ca. Underwent R Hemicolectomy 6 months ago.

• NKDA + Ramipril 2.5mg/ Simvastatin 20mg/ Omeprazole 20mg

• Retired banker and lives at home with wife in a bungalow.

• O/E: Patient looks in pain, Mild SOB

• Abdo is distended. Previous right paramedian scar from R Hemicolectomy. End Colostomy LIF appears healthy. Good output. Abdomen tender, no rebound. Hyper-resonant percussion. Bowel sounds high pitched and tinkling.

• Ix: FBP - WCC up

U+E - K 5.4/ Na 135/ Crt 48/ Urea 12

ABG - PO2 8.4/ pCO2 6.7/ pH 7.32/ HCO3 19

Amylase - 120

LFTs - Normal, Albumin 24

Small Bowel Obstruction

• Clinical Features:

✴Constipation

✴Abdominal Distension

✴Central abdominal pain

✴Failure to pass Flatus

✴Vomiting

• Aetiology:

– Tumours

– Hernias

– Adhesions– Others - Strictures/ Inflammation/ Congenital/ post-op ileus/

haemorrhage

Clinical Case 2

• 24 year old female attends GP with tiredness, generalized abdo discomfort, weight loss and thinks she looks ‘pale’. Reduced appetite over last 3-4 months. Concerned as she’s had to take time off work. Also complains of an extremely itchy rash on elbows, knees and buttocks.

• PMHx: TIDM

• Non-smoker/ social drinker

• O/E: Patient appears pale, but comfortable at rest.

• Abdo - Slightly distended, generalized tenderness, BS Normal

• Ix: FBP - Low Hb, Low MCV, Low MCHC

U+E - Normal

CRP - Slightly raised

LFTs - Normal, but low Albumin

Anti-Endomysial Ab +ve/ Anti-transglutaminase Ab +ve/ Ant-gliadin Ab +ve

Coeliac Disease

• Commonest Autoimmune condition - 1 in 100

• Auto-immune immunologically mediated reaction against gluten

component of gliadin protein found in wheat, rye and barley.

• Genetic susceptibility with HLA haplotypes (HLADQ2/8) – those with

Type 1 diabetes mellitus and autoimmune thyroid disease have an

increased incidence

• Geographical clustering – common among west Ireland

• Can affect an individual at any age from childhood to old age

• Villous destruction by T-cells impairs small bowel absorption and

symptomatology is proportional to the length of bowel involved.

Colon

Large Intestine

MUCOSAEpithelium &

specialisations

Simple columnar - except at recto-anal junction —> SSKE

Brush border + goblet cells

Lamina Propria Loose CT (surrounds the crypts) and lymphoid tissue – abundant in

appendix (MALT)

Muscularis mucosae 2 thin layers of smooth muscle

Inner circular / outer longitudinal

SUBMUCOSA Loose collagenous and elastic CT; lymphoid tissue may bulge down from

lamina propria; nerve plexuses;

MUSCULARISEXTERNA

Inner circular layer

Outer longitudinal as 3 ribbon-like bands - Taeniae Coli

Outer longitudinal – uniform thickness in appendix and rectum

SEROSA/ADVENTITIA

Ascending and descending colon are retro-peritoneal i.e. serosa only on anterior surface

'The main functions of the colon and

rectum are to absorb water and

nutrients from what we eat and to

move food waste out of our body.'

• The colon receives partially digested food, in a liquid

form, from the small intestine.

• Bacteria (bowel flora) in the colon break down some

materials into smaller parts

• The epithelium absorbs water and nutrients. It forms the

remaining waste into semi-solid material, faeces.

• The epithelium also produces mucus at the end of the

digestive tract, which makes it easier for stool to pass

through the colon and rectum.

• Sections of the colon use peristalsis to move the stool to

the rectum.

• The rectum is a holding area for the stool. When it is

full, it signals the brain to move the bowels and push the

stool from the body through the anus.

Clinical Case 3

• 67 year old lady presents to GP with change in bowel habit approx 8 weeks with intermittent diarrhoea and constipation. She has passed some blood PR and generally feels quite tired. Hasn’t taken part in FOB screening.

• PMHx: Hypertension

• FHx: Nil of note

• Social Hx: Social alcohol and non-smoker

• O/E: She appears comfortable at rest, but has yellow sclera.

• Abdomen - Palpable mass in RIF and palpable liver edge that feels nodular. PR examination reveals some blood on gloved finger.

• Ix: FBC - Low Hb

U+E - Normal

LFTs - ALP/ ALT/ GGT/ AST raised

CEA – Raised

Fe Profile – Fe def anaemia

Colonoscopy

Sigmoid Colon Carcinoma -Stage IV

Colorectal Cancer

• 3rd commonest Cancer in UK

• 2nd commonest cause of death by cancer

• 1 in 20 Females/ 1 in 16 Males in NI

• 2/3 Colon + 1/3 Rectum

• National Screening Programme - FOB (60-

74 yrs every 2 years)

Risk Factors

• Genetic: FAP/ HNPCC/ Peutz-Jeghers/ Gardners Syndrome

• Pre-existing: IBD/ CRC/ Pelvic Cancers/ Previous CTX/ Colorectal polyps

• General: Increasing age/ FHx/ Lifestyle/ Geographical

Pathophysiology

Adeno-Carcinoma Sequence

Red Flag Criteria

•40-60yrs old, rectal bleeding and change in bowel habit > 6weeks

•>60 yrs old, rectal bleeding only for > 6weeks

•>60 yrs old change in bowel habit only for > 6weeks

•Palpable abdominal mass

•Palpable rectal mass

•Fe2+ deficiency anaemia (Men <11g/dL, Women <10g/dL)

Right Sided Tumour Left Sided Tumour Rectum

• Mass in RIF• ‘Appendicitis’ type

pain • Fe def anaemia Blood

mixed in stool• Diarrhoea• Mucus

• Mass in LIF• Change in bowel

habit – constipation• PR bleeding• Colicky abdo pain

• Tenesmus• Urgency• Incomplete

evacuation + straining• Increased frequency• Bright red PR

bleeding Constipation or diarrhoea

• Palpable mass PR

Questions?