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Small + Large BowelBMA Revision DayAndrew McCorkell
2
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
9
Function
• Absorption
• Enzymatic Digestion
10
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?