week 5- pancreas, lower GI inflammation

what causes mucosal inflammation?

autoimmune (eg. IBD), Infective, disuse/diversion colitis, ischemic colitis, drug-induced, luminal occlusion

colitis= inflammation of colon

what causes lumenal obstruction and what are its 2 categories?

•Lymphoid hyperplasia

•Faecolith (hard, stone-like mass of calcified fecal matter)

•Foreign body (faeces)

•Tumour

2 categories:

Chemical-induced inflammation

Bacterial-induced inflammation

describe the presentation of Lower GI inflammation

Mucosal Inflammation

•Mucosal disruption

•Bleeding

•Bacterial translocation

•Reduced mucosal function

•Secretory/ reduced absorption -> diarrhoea

•Nutritional failure

Transmural Inflammation

•Peritonitis/ perforation

•Acute obstruction

Late Presentation

•Stricture/ fibrosis

•Fistulation

•Cancer

explain the evolution of abdominal findings

describe the Clinical course and histological differences between Ulcerative Colitis and Crohn's diseases and determine the role of surgery in management of IBD (UC and Crohn’s are 2 examples of IBD)

	Ulcerative Colitis	Crohn's Disease
Site	Colon Continuous	Entire GI tract, including perianal Skip lesions
Inflammation	Mucosal/ submucosal Involves mesentery No granulomas	Transmural Presence of granulomas
Intent of surgery	Curative	Management of complications (strictures, fistulae, abscess)

explain the surgical considerations in Ulcerative Colitis

•Approx. 10% of patients within 10 years will require surgery

•Surgery is curative

•Indications

Fulminant/ toxic colitis

Medical refractory

Patient preference

Complications (dysplasia, cancer...)

•Extent of surgery is dependent on presentation

Emergency/ urgent => subtotal colectomy

Elective => panproctocolectomy

•Can consider restorative procedure

(A panproctocolectomy removes the entire colon and rectum, while a total colectomy removes only the entire colon, leaving the rectum intact)

explain the surgical considerations in Crohn’s disease

Up to 75% of patients with Crohn's disease will eventually require surgery

•Not curative as may recur anywhere

•Intentions of surgery

         Relieve complications

         Maintain quality of life

        Preserve gut length and nutritional competence

•High risk of complications, including fistulation/ intestinal failure

•Generally not feasible to perform a restorative procedure following proctocolectomy (permanent stoma)

describe the management of lower GI inflammation

•Stepwise approach – conservative > invasive

•Treat underlying pathology if possible

•Fluid resuscitation/ anticoagulation

•Antibiotics

•Immunosuppression

•Cessation of offending drug

•In event of failure, surgery not always required

•Interventional radiology

•Sometimes surgery is the answer!

name the regions where the duodenum, pancreas and spleen are found

Duodenum

•Epigastric region, umbilical region

Pancreas

•Epigastric, left hypochondrium, umbilical region

Spleen

•Left hypochondrium

•Protected by ribs 9-11

All in the right and left upper quadrants

the duodenum and pancreas also Partly sit in the transpyloric plane

describe the gross structure of the duodenum

•From the pylorus to duodenojejunal junction.

•25cm long, C-shaped, around the pancreas, vertebral level L1-3

•Mostly retroperitoneal

4 parts: Superior, descending, inferior, ascending

1^st part - superior

•5cm long

•From pylorus to superior duodenal flexure

•2.5cm intraperitoneal (duodenal cap),2.5cm retroperitoneal

2^nd part – descending

•8cm long, between superior and inferior duodenal flexures

•Major (openings from the common bile duct) and minor (openings from the pancreas) papillae

•In the major papillae the ampulla (of Vater) is found, a ductal structure that forms from the union of the common bile duct and the pancreatic duct

3^rd part – inferior (horizontal)

•10cm long

•Inferior to the pancreas

•Coursing left

4^th part – ascending

•2.5cm long

•To duodenojejunal flexure at L2

•Suspensory muscle of the duodenum attaches to the crus of the diaphragm

describe the gross structure of the pancreas

•Retroperitoneal organ

•15cm long, sits within C-shaped, of duodenum

•Lies obliquely at vertebral level L1-2

•5 parts: head, neck, body, tail, uncinate process

•The neck is anterior to the confluence of the superior mesenteric vein and splenic vein which come to form the hepatic portal vein

•General glandular appearance

describe the Internal system of ducts

•Main pancreatic duct

(Becomes wider the closer it gets to the duodenum/terminal portion/the head)

Meets the bile duct at the hepatopancreatic ampulla

Major duodenal papilla

•Accessory pancreatic duct

Connects with main duct

Minor duodenal papilla

Sometimes not present

describe the gross structure of the spleen

•Largest lymphoid organ

Size varies

•Thin capsule

•Diaphragmatic and visceral surfaces

Separate ‘areas’ and surfaces

•Intraperitoneal

•Gastrosplenic ligament (thickening of the greater omentum)

•Splenorenal ligament (thickening of the greater omentum)

•Phrenicosplenic ligament

List the key anatomical structures related to the spleen.

•Stomach – anterior to the spleen

•Kidney –medial and inferior to the spleen

•Colon- at the splenic flexure, medial and anterior

•Pancreas- the tail is medial

•Diaphragm and ribs - lateral to spleen

List the key anatomical structures related to the pancreas and duodenum

•Stomach- anterior to the pancreas and duodenum

•Lesser sac- anterior to the pancreas and duodenum

•Transverse colon- anterior to the pancreas and duodenum

•Aorta/IVC- posterior to the pancreas and duodenum

•Kidney/ureter- closely associated with the superior and descending parts of the duodenum, and lateral to the head of the pancreas

•Gall bladder- anterior to the first part of the duodenum

•Bile duct- duct within/posterior to pancreas, posterior to duodenum

•Superior mesenteric artery/vein- posterior to the neck and body, but become anterior to the head and uncinate process of the pancreas, anterior to the duodenum

•Celiac trunk- superior to the pancreas

•Gastroduodenal artery- posterior to the superior portion of the duodenum, superior to pancreas

•Splenic vein- posterior to the pancreas

•Hepatic portal vein - posterior to the pancreas

describe the blood supply of the spleen, pancreas and duodenum

Celiac Trunk

•Splenic artery – spleen

•Dorsal pancreatic artery/pancreatic branches – pancreas neck/body/tail

•Gastroduodenal artery

•Anterior/posterior superior pancreaticododenal arteries – pancreas head/uncinate process, duodenum

•Small pancreatic branches – pancreas

•Retroduodenal branches/supraduodenal artery – proximal duodenum

 it only supplies the first 2 parts of the duodenum (superior and descending)

Superior mesenteric artery

•Anterior/posterior inferior pancreaticododenal arteries – pancreas head/uncinate process, duodenum

•Small pancreatic branches – pancreas

•First jejunal branch– distal duodenum

it only supplies the last 2 parts of the duodenum (inferior and ascending)

describe the venous drainage of the pancreas, spleen and duodenum

Part of the portal system (including the spleen)

Splenic vein and SMV unite posterior to pancreas neck – hepatic portal vein

Smaller branches follow pattern and names of arteries

Anterior superior PDA - SMV

Posterior superior PDA - hepatic portal vein

A/P inferior PDA – SMV

^{(look at picture to remember)}

PDA= pancreaticoduodenal vein

SMV=superior mesenteric vein

The inferior mesenteric vein (IMV) can drain in the splenic vein (shown in the picture), or in the SMV, this is an anatomical variation

describe the lymphatic drainage of the duodenum, pancreas and spleen

Organ	Primary Nodes	Secondary Nodes	Final Pathway
Duodenum	Pancreaticoduodenal, mesenteric	Pyloric, superior mesenteric, celiac	Intestinal trunks → Cisterna chyli → Thoracic duct → Left venous angle
Pancreas	Head: Pancreaticoduodenal Body/Tail: Pancreaticosplenic	Pyloric, superior mesenteric, celiac	Intestinal trunks → Cisterna chyli → Thoracic duct → Left venous angle
Spleen	Pancreaticosplenic	Celiac	Intestinal trunks → Cisterna chyli → Thoracic duct → Left venous angle

outline the nerve supply of the duodenum, pancreas and spleen

Parasympathetic

•Vagal trunks

Sympathetic

•Greater and lesser splanchnic – T5-T12

the nerves travel alongside the arteries that go to each organ. They use the same path

What is the purpose of the suspensory ligament of the duodenum?

define Splenomegaly and causes

Splenomegaly - enlarged spleen

infections/ haematopoietic conditions (disorders of blood cell formation)

explain the embryology of the pancreas

week 5, from the ventral bud (where the gallbladder and liver also develop) & dorsal bud (comes from the foregut, MUCH larger)

overtime both buds start to mature. The dorsal pancreas grows out into the dorsal mesentery and forms the neck, body and tail of the pancreas. The tail is intraperitoneal, the rest of the pancreas is retroperitoneal.

over week 6 and 7 the ventral pancreas and the common bile duct start to rotate clockwise. The ventral and dorsal buds and ducts start to fuse.

what are the dorsal and ventral ducts of the pancreas called?

Dorsal= Duct of Santorini

Ventral= Duct of Wirsung

explain the embryological variants of the pancreas

•Pancreatic Divisum

Most common

10% of the population

Failure of fusion embryologically

Often asymptomatic

25% recurrent pancreatitis

•Annular Pancreas

Rare congenital abnormality

a ring of pancreatic tissue wrapped around duodenum

Associated Down’s syndrome (1 in 4)

Often asymptomatic

Food intolerance, nausea, vomiting, chronic pain

May co-exist with trache-oesophageal fistula

•Pancreatic Rest

Ectopic pancreatic tissue

1-2% autopsy series

Histological variants – ducts, islets, blood supply

can occur throughout GI tract

predominantly gastric & proximal small intestine

Usually asymptomatic

may cause dyspepsia, pancreatitis, mimic tumours