Week 1 - Endoscopic Tour Flashcards
In endoscopy, what marks the start of the oesophagus?
Cricopharyngeal sphincter
How far is the oesophagogastric mucosal junction usually from the incisor teeth in an adult?
38-40cm
What is barretts’s oesophagus?
Reflux of stomach acid has caused metaplasia of oesophageal epithelium to gastric columnar epithelium
What are oesophageal varicies?
Swollen veins in oesophagus caused by portal hypertension, these may rupture and bleed
How can portal hypertension occur?
Blocked vessels in liver
What is dysphagia?
Swallowing problems
What is achalasia?
Muscles in lower part of oesophagus fail to relax, preventing food from passing into stomach
What is benign stricture?
Diameter of oesophagus narrowed by scar tissue formation
What structures reduce stomach acid reflux?
Lower oesophageal sphincter
Acute angle of entry of oesophagus into stomach produces valve like effect
Mucosal folds at oesophagogastic junction acts as valve
Diaphragm acts as pinch cock
Positive intra-abdominal pressure compresses walls of intra-abdominal oesophagus
What controls passage of stomach contents into duodenum?
Pyloric sphincter
Where is gastric ulceration most commonly found in the stomach?
On the lesser curve at angulus
What is the duodenojejunal flexure supported by?
Ligament of treitz
Where does the duodenum start and finish?
Starts at L1, curves round and ends at L2-3
Where does it sit with respect to the peritoneum?
Starts intraperitoneally
Becomes retroperitoneal
How many divisions are there in the duodenum?
4
How long is the first part of the duodenum?
5cm
How can gallstones affect the first part of the duodenum?
Its overlapped by the gallbladder and gallstones may cause erosion through leading to coledocoduodenal fistula
Where are duodenal ulcers most commonly located?
First part
What damage may an anterior ulcer cause?
May perforate causing peritonitis
What damage may a posterior ulcer cause?
May erode into gastroduodenal artery or into pancreas
How long is the second section of the duodenum?
7.5cm
What structures are related to 2nd section of duodenum?
Wraps around head of pancreas
Where is the major duodenal papilla and what is its significance?
Lays half way along posteromedial aspect of 2nd part of duodenum
Signifies opening of main pancreatic duct
Transition from embryonic foregut to midgut occurs here
What do ulcers in the 2nd section of duodenum suggest?
Pancreatic disease or zollinger-ellison syndrome
What is zollinger-ellison syndrome?
Either gastrin secretion tumour or hyperplasia of islet cells in pancreas causing over production of gastric acid
How long is the third section of the duodenum?
10cm
Where is the third section of the duodenum located?
Runs transversely at level of L2/3
Crosses aorta below origin of superior mesenteric artery
What may happen in patients with a diseased duodenum or aorta?
Development of aorto-duodenal fistula
What runs anterior and posterior to the third section of the duodenum?
Anterior - superior mesenteric artery
Posterior - aorta
What may occur to the duodenum in patients with dramatic weight loss?
May develop SMA syndrome where duodenal obstruction is caused by compression by superior mesenteric artery and aorta
How long is the 4th section of the duodenum?
2.5cm
At which point does the duodenum become intraperitoneal?
At the duodenojejunal flexure
What marks the duodenojejunal flexure?
The suspensory ligament of treitz
Where does the Hillary tree start and what does it form?
Commences wishing the liver from intrahepatic ducts, which form left and right common bile ducts
What is the common hepatic duct formed by?
Convergence of the left and right hepatic ducts at porta hepatic
How long is the common hepatic duct?
4cm
The cystic duct arising from gallbladder joins common hepatic duct to form what?
Common bile duct
How long and wide is the common bile duct?
10cm long
Up to 7cm in diameter
What will blockage of the common bile duct lead to?
Obstruction of bile flow
Jaundice
Disruption to enterohepatic circulation of bile salts
What will patients with a blocked common bile duct present with?
Yellow discolouration
Dark urine
Pale stool
What is the most common cause of painless obstructive jaundice?
Secondary to tumour
What is the most common tumour to cause obstructive jaundice?
Carcinoma of head of pancreas, obstructs common bile duct as it passes either through or in close relation to head of pancreas
What is the most common cause of painful obstructive jaundice?
Gallstone disease
Where does the common bile duct run?
Superior to duodenum, runs in free edge of lesser momentum along with portal vein and hepatic artery
How long is the small intestine?
Varies from 3-10m
What is the small intestine divided into and what are their proportions?
Jejunum - about 2/5
Ileum - about 3/5
How is the jejunum wall different to the wall of ileum?
Thicker due to increased number, larger and taller pillage circulates (circular folds of mucosa)
Also appears deeper red due to greater blood supply
Describe jejunal wall
Tall villi with deep crypts
What happens to jejunal wall in celiac disease?
Villi and crypts atrophy
What is Meckel’s diverticulum and where is it found?
Found in distal ileum
Remnant of embryonic vitellointestinal duct
Only found in 2% of population
May contain gastric mucosa which secretes acids
This may cause bleeding or inflammation
What are payers patches?
Aggregates of lymphoid tissue within wall of small bowel
What problems may occur to payers patches?
Can enlarge, particularly in lymphoma and cause intestinal luminal obstruction
How long is the entire colon?
100-180cm
How is the colon distinguished?
3 longitudinal bands of muscle along its length which form taenoid coli and converge at bas of appendix
What are haustrations?
Sacculations caused by length of muscles being shorter than colon itself, so bunch up the colonic wall
On radiograph, whats the difference between colon and small bowel?
Colon - sacculations appear as incomplete lines and occur at lumen of wall
Small bowel - mucosal folds project across entire width of bowel wall
What is marking the ileocaecal junction and what is the function of this?
Marked by valve which prevents back flow of colonic contents during peristalsis
What may happen if the caecum becomes obstructed?
May dilate to the point of necrosis or perforation if ileocaecal valve is competent as prevents back flow of both air and colonic contents
Where does the caecum lie?
Right iliac fossa
What is the presentation of a right sided colon tumour?
Mass
Change in bowel habit
Iron deficiency anaemia
Pain
Where does the appendix arise from?
Postero-medial aspect of caecum
How long is the ascending colon?
12-20cm
Where does the ascending colon end?
At hepatic flexure
How long is the transverse colon
45cm
Where does the transverse colon end?
Splenic flexure
What level is the transverse colon found?
Level of umbilicus but ay hang down into pelvis
How long is the descending colon?
22-30cm
How long is the sigmoid colon?
Average length is 37cm but may be as long as 70cm
What are appendices apoploicae?
Fat-filled peritoneal tags found on outer surface of colon
What problems may occur due to sigmoid colons length and loose attachment?
May twist on itself forming sigmoid volvulous
What will as sigmoid volvulous present with?
Symptoms of large bowel obstruction
What are colonic diverticulum?
Out pouching of bowel wall
What is the most common location of colonic diverticulum?
Sigmoid colon and comply occurs where artery pierces muscular wall causing weakness
How long is the rectum?
12cm
Where does the rectum start?
Anterior to sacrum at S3
Where is the most common site of colon cancer?
Rectum
What are the features of ulcerative colitis?
Tends to occur in rectum and spread proximally throughout colon
Areas of inflammation are continuous and mucosa highly friable
What are the features of crowns disease?
Patchy or focal areas of inflammation known as skip lesions
Associated ulcers are often deep and fissuring and produce a cobblestones appearance
How long is the anal canal?
4cm
What are the features of the upper anal canal?
Part of hind gut and lined by columnar epithelium
What are the features of the mid anal canal?
Transition between endoderm of hind gut and ectoderm of proctodaeum invagination from skin
Area marked by valves of ball
Line formed by these valves is known as dentate or pectineal line
What epithelium is found below the dentate line?
Stratified squamous epithelium
What artery supplies the upper rectum?
Inferior mesenteric artery
What is the innervation of the upper rectum?
Visceral pelvic splash nice nerves arising from sympathetic chain and S2,3 and 4
What type of pain is felt in the upper rectum?
Dull and poorly located
What is the venous drainage of the upper rectum?
Into portal system via inferior mesenteric vein
What artery supplies the lower rectum?
Inferior rectal artery - branch of internal iliac
What is the innervation of the lower rectum?
Inferior rectal nerve - somatic
What type of pain is felt in the lower rectum?
Sharp and well defined
What is the venous drainage of the lower rectum?
Internal iliac vein
What is a haemorrhoid?
Dilatation of superior rectal vein
If confined above dentate line they are relatively painless
If extend below it will be extremely painful
What types of tumours are found in the rectum?
Upper rectum - adenocarcinoma
Lower rectum - generally squamous cell carcinoma
