Week 3 - F - Small bowel - Obstruction/Ischaemia (acute/chronic)/Meckel's diverticulum/Tumours, Appendicitis (mass/abscess)

Question 1

Which arteries does the small bowel blood supply come from?

Answer 1

Some bowel blood supply comes from the jejunal and ileal branches of the superior mesenteric artery (comes from aorta at L1)

Question 2

What can wrong with the small bowel Many different things can go wrong - big problems include * Obstruction * Infarction * Bleeding
What are two main causes of small bowel obstruction?

Answer 2

Causes can be split into things that occur within the lumen, within the wall and more commonly - outside the wall
Outside the bowel wall - Intra-abdominal adhesions are the most common cause of small bowel obstruction, followed by hernias.

Question 3

Rarer causes tend to occur within the bowel wall or within the lumen of the bowel itself What are examples of these causes of small bowel obstruction? (2)(3)

Answer 3

Small bowel obstruction caused within the lumen
* Gallstone ileus
* Food / Bezoar (a solid mass of indigestible material that accumulates in your digestive tract, sometimes causing a blockage)

Small bowel obstruction caused within the wall
* Tumour
* Crohn’s
* Radiation

Question 4

What is the typical presentation in a patient with small bowel obstruction? What may be seen on examination?

Answer 4

Typical presentation
* Distension
* Vomiting
* Borborgymi - rumbling stomach
* Pain
* Faeculent vomiting
On examination may see scars meaning previous abdominal operation (predisposes to adhesions) or need to look for signs of small bowel hernia - both femoral and inguinal

Question 5

How is the diagnosis of small bowel obstruction confirmed?

Answer 5

* Abdominal Xray (AXR)
* CT scan of abomen
Gastrogaffin studies may help with CT - radiographic dye is swallowed by the patient

Question 6

How is AXR able to differentiate between small and large bowel obstuction?

Answer 6

In small bowel obstruction - AXR will show central gas shadows with plicae circularis (aka valvulae conniventes) that completely cross the lumen
In large bowel obstructin AXR will show peripheral gas shadows proximal t the blockage ie in caecum but not in rectum

Question 7

What is the management of small bowel obstruction?

Answer 7

MANAGEMENT
Usually conservative - DRIP AND SUCK method
* Start IV fluids and correct any electrolyte disturbances (‘drip’)
* Make the patient nil-by-mouth (NBM) and insert a nasogastric tube to decompress the bowel (‘sucks out air and fluid to relive abdominal swelling’)
* Urinary catheter and fluid balance
* Analgesia as required with suitable anti-emetics

Question 8

Adhesional small bowel obstruction resulting from previous surgery is treated conservatively in the first instance, with a success rate of around 80% Why do you not want to carry out surgery for adhesional small bowel obstruction? How long can drip and suck usually be continued up until? Does the drip and suck method treat hernias?

Answer 8

As far as prevention of adhesional small bowel obstruction is concerned, best approach is to avoid operation as any surgical procedure predisposes to adhesions
* Drip and suck method only treats adhesional small bowel obstruction -up to 72 hour is standard
* Hernias cannot be treated with drip and suck and usually require reduction - manually - to prevent stangulation and necrosis and if problematic surgical reduction

Question 9

When should you surgically intervene in a patient with small bowel obstruction?

Answer 9

Intervene with emergency surgery if there is a strangulation of the bowel as this can cause ischemia and necrosis
Also intervene if there is small bowel perforation

Question 10

What is the surgical management of an obstructed small bowel - carried out if suspecting strnagulation or perforation? What type of incision? Which drugs are given?

Answer 10

Surgical management of small bowel obstruction is usually via a laparotomy using a midline incison
Antibiotics and antithromboembolic measures are also taken

Question 11

Mesenteric ischaemia Mesenteric ischaemia can be classified as chronic or acute What are the main causes of both?

Answer 11

Acute mesenteric ischaemia usually occurs due
* to mesenteric artery occlusion (usually SMA) due to embolus or thrombosus
* mesenteric vein thrombosis
Chronic mesenteric ischaemia usually occurs due to (rare and difficult to diagnose)
* atherosclerotic disease in all three mesenteric arteries (coeliac, super mesenteric, inferior mesenteric)

Question 12

Aside from ischaemia of the small bowel occurring due to * Mesenteric artery atherosclerosis * Thrombosis formation or embolism
What are non-occlusive perfusion insufficiency that can cause the ischaemia?

Answer 12

Non-occlusive perfusion insufficiency of the small bowel can occur due to
* Shock
* Strangulation obstructing venous return
* Drugs eg cocain
* Hyperviscosity

Question 13

What is chronic mesenteric ischaemia often referred to as? What is its presentation?

Answer 13

Chronic mesenteric ischaemia is often referred to as angina of the gut Triad of
* Severe, colicky post-prandial pain (gut claudication)
* Decreased weight (eating hurts)
* Upper abdominal bruit (due to atherosclerotic vessels)
Also can occur with PR bleeding, malabsorption and nausea/vomiting

Question 14

How does acute mesenteric ischaemia tend to present? Where do the emboli come from?

Answer 14

Acute mesenteric ischaemia tends to present as
* Acute severe abdominal pain - constant and central/around RIF
* No/minimal abdominal signs
* Rapid hypovolaemia (shock)
The emboli usually comes from atrial fibrillation, thrombus forms in Left atrium, breaks off and sticks in the narrow superior mesenteric artery
* AF with abdo pain always prompt thoughts of mesenteric ischaemia

Question 15

Is chronic or acute mesenteric ischaemia more common?

Answer 15

Acute mesenteric ischaemia is more common however it can present as chronic

Question 16

What is odd about the pain in acute mesenteric ischaemia? What is seen on blood tests in acute mesenteric ischaemia?

Answer 16

The pain in acute mesenteric ischaemia is out of proportion to the clinical findings
* Hb may be elevated
* WCC may be elevated
* Consistent metabolic acidosis - high lactate due to anaerobic bowel

Question 17

What is used to try and diagnose mesenteric ischaemia? (acute or chronic)

Answer 17

CXR - may show evidence of a gasless abdomen
CT angiography is usually used to find evidence of ischaemia
Often the diagnosis is made at laparotomy if acute mesenteric ischaemia

Question 18

What is the progression of acute mesenteric ischaemia as time goes on? Can be classified by the degree of infarction

Answer 18

Mucosal infarct - mucosal layer
Mural infarct - mucosal and submucosal layer affected
Transmural infarct - full thickness infarct of the gut

Question 19

What are the complications of acute mesenteric ischaemia? Why is it important to carry out surgery in a patient with chronic mesenteric ischaemia?

Answer 19

Complications include
Fibrosis/stricture of the small bowel
Chronic ischaemia
Gangrene resulting from necrosed tissue
DEATH - poor prognosis
Important to carry out surgery if patient is diagnosed with chronic mesenteric ischaeima - angioplasty and stenting - this is to prevent ongoing risk of acute mesenteric ischaemia

Question 20

What is the treatment for acute mesenteric ischaemia?

Answer 20

Resuscitate the patient if shock and provide antibitoics
* URGENT SURGERY
* Dead bowel must be resected
* Attempt to revascularise viable small bowel

Question 21

What is meckel’s diverticulum?

Answer 21

Meckel’s diverticulum is the result of incomplete regression of the vitello-intestinal duct
The omphalomesenteric duct (omphaloenteric duct, vitelline duct or yolk stalk) normally connects the embryonic midgut to the yolk sac ventrally, providing nutrients to the midgut during embryonic development.
The vitelline duct narrows progressively and disappears between the 5th and 8th weeks gestation.
In Meckel’s diverticulum, the proximal part of vitelline duct fails to regress and involute, which remains as a remnant of variable length and location

Question 22

What does meckel’s diverticulum contain?

Answer 22

Meckel’s diverticulum, formed due to failure of complete regression of the the vitello-intestinal duct contains ectopic ileal, gastric or pancreatic mucosa

Question 23

What is the rule of 2s in Meckel’s diverticulum?

Answer 23

The tubular structure
Occurs in about 2% of the population
Only 2% of cases are symptomatic
Usually presents among children at the age of 2
Is 2 inches long
Is 2foot (60cm) from the ileocaecal valve

Question 24

What is the presentation Meckel’s diverticulum?

Answer 24

Meckel’s diverticulum are diagnosed when complications manifest or incidentally in unrelated conditions such as laparotomy, laparoscopy or contrast study of the small intestine.
* Inflammation can cause symptoms that mimic appendicitis
* Can present as rectal bleeding
* Can present as intestinal obstruction

Question 25

What are complications of meckel's diverticulum?

Answer 25

It can bleed (haematochezia) - painless rectal bleeding commonly occurs in children Ulcerate/become inflamed - meckel's diverticulitis - mimics appendicits Can cause intestinal obstruction Can become malignant

Question 26

What is the management of Meckel's diverticulum?

Answer 26

Management removal if narrow neck or symptomatic

Question 27

Tumors of the small bowel Primary tumours are very rare Secondary tumours (metastases) are much more common What do the primary tumours of the small bowel include? Which tumours commonly metastasise to the small bowel?

Answer 27

Primary small bowel tumours \* Lymphoma \* Carcinoid tumours Carcinoma Metastases to the small bowel \* Ovary \* Colon \* Stomach

Question 28

What is the most common type of primary small bowel cancer? What increases the risk of small bowel cancers?

Answer 28

Most common type is small bowel adenocarcinoma - in glandular cells in the lining of the small intestine Risk factors include \* Crohn's disease \* Coeliac's disease \* Familial adenomatous polyposis \* Hereditary nonpolyposis colorectal cancer - Lynch syndrome

Question 29

What is the treatment of primary small bowel cancers?

Answer 29

Surgery to resect the tumour - curative intent or bypass the tumour to allow food to bypass the obstruction Radiotherapy and chemotherapy are also options for palliative care

Question 30

APPENDICITIS Appendicitis is the most common surgical emergency and can occur at any age Although it can occur at any age, what decade is their the highest incidence? What is the classical presentation of appendicits?

Answer 30

Although it can occur at any age, 2nd decade of life is commonest - between 10-29 Presents typically with \* Classical periumbilical pain (visceral stretching of appendix lumen and appendix is midgut structure) \* Which spreads to RIF due to localized peritoneal inflammation Pain often worse on coughing or going over speed bumps

Question 31

What are other presenting features of appendicitis? Where does the pain in appendicits tend to lateralise?

Answer 31

Tachycardia, fever Anorexia - loss of appetite Vomiting is rarely prominent Diarrhoea is rare Pain tends to lateralise in McBurney's point - 2/3rd of the way from umbilicus to right anterior superior iliac spine

Question 32

What is seen on examination of the patient in appendicits?

Answer 32

\* Peritonitis (if perforation)-guarding or rebound tenderness (pain upon removal of pressure rather than application of pressure to the abdomen) \* Pain on right during PR examination - suggests inflamed low lying pelvic appendix \* Rovsing's sign - pressing on the LIF causes pain in RIF \* Psoas sign - pain on extending the right hip because appendix is lying on psoas major \* Obturator sign (Cope sign) - if appenxdix is touching obturator internus, pain on flexing and internally rotating the hip

Question 33

The aetiology of acute appendcitis is mostly unknown however there are some potential causes What is thought to be different causes of acute appendicitis?

Answer 33

\* Faecoliths - a stone made of feces. It is a hardening of feces into lumps of varying size and may occur anywhere in the intestinal tract but is typically found in the colon. It is also called appendicolith when it occurs in the appendix and is sometimes concomitant with appendicitis. \* Lymphoid hyperplasia \* Bacterial, viral or parasite infection

Question 34

What investigations are carried out in the diagnosis of appendicitis?

Answer 34

\* Typically raised inflammatory markers on bloods (CRP and WCC) with clinical history should be enough to justify appendectomy \* Urine analysis - exclude pregnancy in women and exclude UTI \* US may be all that is necessary to diagnose CT has high diagnostic accuracy and is useful if diagnosis is unclear

Question 35

What is the management of appendicitis?

Answer 35

Analgesia, antibitoics and surgery Laproscopic appendictomy is 1st line Laparotomy appenectomy is 2nd line (recent studies confirm that antibiotics can manage the condition alone - many patients go on to require later appendectomy however)

Question 36

What are the different complications of appendicitis?

Answer 36

Perforation of the appendix into peritoneum - peritonitis Appendix mass Appendix abscess Fistula

Question 37

What is the difference between an appendix mass and an appendix abscess? What is the difference in treatment?

Answer 37

An appendiceal mass is an inflammatory tumor consisting of the inflamed appendix, its adjacent viscera, and the greater omentum - usually an attempt of the body to try and heal the appendix itself Appendiceal abscess can occur if appendix mass fails to resolve - it is a pus-containing appendiceal mass

Question 38

How is an appendix mass / abscess diagnosed? How are they treated?

Answer 38

US/CT may help with the diagnosis of appendix mass/abscess Antibitoics are 1st line for appendix mass - surgery if it fails Treatment usually involves surgical drainage and antibiotics