6.13 - General surgery in the GI tract Flashcards
1
Q
What is acute abdomen (and what are the four types of causes)?
A
Sudden, acute onset abdominal pain, generally requiring surgery (causes: infection, inflammation, obstruction, vascular accident)
2
Q
What do we look for in regards to the patient’s presenting complaint for acute abdomen?
A
- pain assessment (SOCRATES)
- associated symptoms (e.g. vomiting, diarrhoea, fever)
3
Q
Apart from presenting complaint, what else do we ask about for acute abdomen? (3)
A
- PMHx - past medical history
- DHx - drug history
- SHx - social history
4
Q
What range of investigations are there for acute abdomen? (4)
A
- bloods (VBG, FBC, CRP, U&Es, LFTs, amylase)
- urinalysis + urine MC&S (check for UTIs)
- imaging (erect CXR, AXR, CTAP, CT angiogram, USS)
- endoscopy
5
Q
What is CTAP?
A
CT of abdomen and pelvis
6
Q
When do you do CT angiogram?
A
When you suspect bleeding or infarction - delineates blood vessels
7
Q
Why do we do erect CXR for acute abdomen?
A
A viscous perforation can cause bubbles to accumulate under the diaphragm, which is an emergency
8
Q
What are the three approaches to management of acute abdomen?
A
- ABCDE (airways, breathing, circulation, disability, everything else/exposure)
- conservative management
- surgical management
9
Q
What differential diagnoses are associated with RUQ pain? (8)
A
- biliary colic
- cholecystitis / cholangitis
- duodenal ulcer
- liver abscess
- portal vein thrombosis
- acute hepatitis
- nephrolithiasis
- RLL pneumonia
10
Q
What differential diagnoses are associated with epigastric pain? (8)
A
- acute gastritis / GORD
- gastroparesis
- peptic ulcer disease/perforation
- acute pancreatitis
- mesenteric ischaemia
- AAA
- aortic dissection
- myocardial infarction
11
Q
What differential diagnoses are associated with LUQ pain? (6)
A
- peptic ulcer
- acute pancreatitis
- splenic abscess
- splenic infarction
- nephrolithiasis
- LLL pneumonia
12
Q
What differential diagnoses are associated with RLQ pain? (8)
A
- acute appendicitis
- colitis
- IBD
- infectious colitis
- ureteric stone / pyelonephritis
- PID / ovarian torsion
- ectopic pregnancy
- malignancy
13
Q
What differential diagnoses are associated with suprapubic/central pain? (8)
A
- early appendicitis
- mesenteric ischaemia
- bowel obstruction
- bowel perforation
- constipation
- gastroenteritis
- UTI / urinary retention
- PID
14
Q
What differential diagnoses are associated with LLQ pain? (8)
A
- diverticulitis
- colitis
- IBD
- infectious colitis
- ureteric stone / pyelonephritis
- PID / ovarian torsion
- ectopic pregnancy
- malignancy
15
Q
How do patients with bowel ischaemia present? (3)
A
- sudden onset crampy abdominal pain
- severity of pain depends on length and thickness of colon affected
- bloody, loose stool (currant jelly stools)
- fever + signs of septic shock
16
Q
What are the risk factors for bowel ischaemia? (6)
A
- age >65 years
- cardiac arrhythmias (mainly AF), atherosclerosis
- hypercoagulation / thrombophilia
- vasculitis
- sickle cell disease
- profound shock causing hypotension
17
Q
What are the two types of bowel ischaemia?
A
- acute mesenteric ischaemia - embolic events (so look for cardiac arrhythmias), transmural ischaemia
- ischaemic colitis - more to do with hypertension, mainly mucous
18
Q
Which bowel does acute mesenteric ischaemia vs ischaemic colitis affect?
A
Small bowel vs large bowel
19
Q
What is acute mesenteric ischaemia vs ischaemic colitis caused by?
A
- AMI - usually occlusive and secondary to thromboemboli
- IC - usually due to non-occlusive low flow states or atherosclerosis
20
Q
What is the onset of acute mesenteric ischaemia vs ischaemic colitis?
A
- AMI - sudden onset (but presentation and severity varies)
- IC - more mild and gradual (80-85% of the cases)
20
Q
What is the pain like for acute mesenteric ischaemia vs ischaemic colitis?
A
- AMI - abdominal pain out of proportion of clinical signs (often see no clinical signs at all)
- IC - moderate pain and tenderness (generally less severe)
21
Q
How can atrial fibrillation contribute to acute mesenteric ischaemia?
A
- if someone has AF, a small clot can get blocked in the SMA
- if complete obstruction of the SMA, you lose all of bowel from DJ flexure to splenic flexure (all of small bowel and 3/4 of large bowel)
22
Q
What three types of investigation do we do for bowel ischaemia?
A
- bloods
- imaging - CTAP / CT angiogram
- endoscopy
23
Q
What bloods do we do for bowel ischaemia, and what would we see? (2)
A
- FBC - neutrophilic leukocytosis
- VBG - lactic acidosis
24
What does seeing lactate on VBG tell us in bowel ischaemia?
- switch to anaerobic respiration
- form of metabolic acidosis associated with late stage mesenteric ischaemia and extensive transmural intestinal infarction
- late stage = bowel already dead (ideally want to intervene before this happens)
25
What do imaging (CTAP / CT angiogram) for bowel ischaemia detect? (4)
- disrupted flow
- vascular stenosis (narrowing of lumen due to extrinsic factors i.e. aneurysms, tumours)
- pneumatosis intestinalis (transmural ischaemia/infarction) - air in bowel wall, bowel already dead
- thumbprint sign (unspecific sign of colitis)
26
When is endoscopy used for bowel ischaemia?
For mild or moderate causes of ischaemic colitis
27
What do we look for on endoscopy of ischaemic bowel? (3)
- oedema
- cyanosis
- ulceration of mucosa
28
What type of bowel ischaemia can we do conservative management for?
Mild to moderate cases of ischaemic colitis
29
What type of bowel ischaemia is conservative management **not** suitable for?
Small bowel ischaemia - acute mesenteric ischaemia
30
What does conservative management of bowel ischaemia consist of? (7)
- IV fluid resuscitation
- bowel rest (NBM)
- broad spectrum ABx (colonic ischaemia can result in bacterial translocation and sepsis)
- NG tube for decompression (they can get concurrent ileus, where bowel does not do peristalsis)
- anticoagulation
- treat/manage underlying cause
- serial abdominal examination and repeat imaging
31
What are the indications for surgical management of bowel ischaemia? (5)
- small bowel ischaemia (acute mesenteric ischaemia)
- signs of peritonitis (rigid abdomen) or sepsis
- haemodynamic instability
- massive bleeding
- fulminant colitis with toxic megacolon
32
How do we do exploratory laparotomy for bowel ischaemia?
Resection of necrotic bowel with/without open surgical embolectomy (balloon catheter in SMA to pull out thrombus) or mesenteric arterial bypass (rare)
33
What does dead bowel vs healthy bowel look like?
- dead = purple, inflamed
- healthy = pink
34
What is endovascular revascularisation for bowel ischaemia?
- another technique to try before surgery
- balloon angioplasty/thrombectomy in patients without signs of ischaemia
35
How does acute appendicitis present? (5)
- initially periumbilical pain that migrates to RLQ (within 24 hours)
- anorexia (ask if they feel like eating)
- nausea +/- vomiting
- low grade fever
- change in bowel habit (inflamed appendix adjacent to rectum and can irritate it)
36
What are some important clinical signs seen in acute appendicitis? (5)
- McBurney's point
- Blumberg sign
- Rovsing sign
- Psoas sign
- Obturator sign
37
What is McBurney's point (acute appendicitis)?
Tenderness in RLQ (lateral 1/3 of a hypothetical line drawn from the right ASIS to the umbilicus)
38
What is Blumberg sign (acute appendicitis)?
Rebound tenderness especially in right iliac fossa (pain on pressure removal rather than application)
39
What is Rovsing sign (acute appendicitis)?
RLQ pain elicited on deep palpation of the LLQ
40
What is Psoas sign (acute appendicitis)?
RLQ pain elicited on flexion of right hip against resistance
41
What is Obturator sign (acute appendicitis)?
RLQ pain on passive internal rotation of the hip with hip & knee flexion
42
What three types of investigations are there for acute appendicitis?
- bloods
- imaging
- diagnostic laparoscopy
43
What bloods are done for acute appendicitis, and what would you see? (4)
- FBC - neutrophilic leukocytosis
- raised CRP
- urinalysis - possible mild pyuria (WBCs present) / haematuria
- electrolyte imbalances in profound vomiting
44
What imaging tests are done for acute appendicitis? (3)
- CT - gold standard in adults especially if age>50
- USS - children/pregnancy/breastfeeding (radiation)
- MRI - in pregnancy if USS inconclusive
45
When is diagnostic laparoscopy done for acute appendicitis?
In persistent pain and inconclusive imaging
46
What is the Alvarado score for acute appendicitis?
Clinical scoring system for appendicitis:
- RLQ tenderness = 2
- fever (>37.3) = 1
- rebound tenderness = 1
- pain migration = 1
- anorexia = 1
- nausea +/- vomiting = 1
- WCC > 10.000 = 2
- neutrophilia (left shift 75%) = 1
/=7 likely
47
What does conservative management of acute appendicitis consist of? (4)
- IV fluids
- analgesia
- IV or PO antibiotics
- in abscess, phlegmon (inflammation of soft tissue that spreads under skin/inside body) or sealed perforation:
- resuscitation + IV ABx +/- percutaneous drainage
48
What are the indications for conservative management of acute appendicitis? (2)
- after negative imaging in selected patients with clinically uncomplicated appendicitis
- in delayed presentation with abscess/phlegmon formation --> do CT-guided drainage
49
What do we consider after conservative management of acute appendicitis?
Interval appendicectomy as rate of recurrence after conservative management of abscess/perforation is 12-24%
50
Why is laparoscopic surgery better than open appendicectomy? (6)
- less pain
- lower incidence of surgical site infection
- decreased length of hospital stay
- earlier return to work
- overall costs
- better QoL scores
51
What are the steps of a laparoscopic appendicectomy? (Do not need to know?)
1. trocar placement (usually 3)
2. exploration of RIF + identification of appendix
3. elevation of appendix + division of mesoappendix (containing artery)
4. base secured with endoloops and appendix divided
5. retrieval of appendix with a plastic retrieval bag
6. careful inspection of the rest of the pelvic organs/intestines
7. pelvic irrigation (wash out) + haemostasis
8. removal of trocars + wound closure
52
What is the definition of intestinal obstruction?
Restriction of normal passage of intestinal contents
53
What are the two main groups of intestinal obstruction?
- paralytic (adynamic) ileus - pus etc irritates bowel which stops peristalsis until irritation gone
- mechanical
54
What are the four different ways to classify a mechanical intestinal obstruction?
- speed of onset - acute, chronic, acute-on-chronic
- site - high or low (roughly synonymous with small or large bowel obstruction)
- nature - simple vs strangulating
- aetiology
55
What is the difference between a simple vs strangulating bowel obstruction?
- simple - bowel is occluded without damage to blood supply
- strangulating - blood supply of involved segment of intestine is cut off (e.g. in strangulated hernia, volvulus, intussusception)
56
What is a volvulus?
Imagine a party balloon being twisted giving you a closed loop - but with intestines twisting
57
What is an intussusception?
When a bit of bowel slides into the next bit
58
What are the causes of mechanical intestinal obstruction? (3)
- causes in the lumen e.g. faecal impaction, gallstone ileus (fistula)
- causes in the wall - Crohn's disease (thickening of SB wall), tumours, colon diverticulitis
- causes outside the wall - strangulated hernia (external or internal), volvulus, obstruction due to adhesions or bands
59
What are the causes of small bowel obstruction? (5)
- adhesions (60%) - Hx of previous abdominal surgery
- neoplasia (20%) - primary, metastatic, extraintestinal
- incarcerated hernia (10%) - external (abdominal wall), internal (mesenteric defect)
- Crohn's disease (5%) - acute (oedema), chronic (strictures)
- other (5%) - intussusception, intraluminal (foreign body, bezoar)
60
What are the causes of large bowel obstruction? (5)
- colorectal carcinoma (usually LHS since RHS can expand and compensate)
- volvulus - sigmoid, caecal
- diverticulitis - inflammation, strictures
- faecal impaction
- Hirschsprung disease - commonly in infants/children (lack of nerve ganglions means no peristalsis)
61
What are the 4 main signs/symptoms (and three other signs/symptoms) of bowel obstruction?
- abdominal pain
- vomiting
- absolute constipation
- abdominal distention
Other signs:
- dehydration
- increased high pitch tinkling bowel sounds AKA borborygmi (early sign)
- or absent bowel sounds (late sign and bad as peristalsis has stopped, may have ischaemic bowel)
- diffuse abdominal tenderness (worrying)
62
How does abdominal pain differ between small and large bowel obstruction?
- SBO - colicky, central
- LBO - colicky or constant
63
How does vomiting differ between small and large bowel obstruction?
- SBO - early onset, large amount, bilious (with bile)
- LBO - late onset, initially bilious, progresses to faecal vomiting (looks like faeces)
64
How does absolute constipation differ between small and large bowel obstruction?
- SBO - late sign
- LBO - early sign
65
How does abdominal distention differ between small and large bowel obstruction?
- SBO - less significant
- LBO - early sign and significant
66
What are 3 important points to remember about diagnosing intestinal bowel obstruction?
- diagnosed by the presence of symptoms
- examination should always include a search for hernias and abdominal scars, including laparoscopic potholes
- is it simple or strangulating? (hernia)
67
What are features suggesting strangulation (hernia)? (7)
- change in character of pain from colicky to continuous
- tachycardia
- pyrexia
- peritonism (rigid abdomen)
- bowel sounds absent or reduced (initially increased)
- leucocytosis
- increased CRP
68
Why is checking for strangulation (of hernia) important?
Strangulating obstruction with peritonitis has mortality of up to 15%
69
What is a hernia?
Contents of bowel protrude outside its sac/cavity
70
What are some common sites of hernias? (5)
- inguinal - due to defects in abdominal wall
- femoral - due to defects in abdominal wall
- incisional hernia - skin healed but muscle underneath has defect so bowel protrudes through
- umbilical hernias - around umbilicus
- epigastric hernias - around epigastrium
71
Why is the neck of the hernia sac important?
- if it is large, the bowel can get in/out easily
- smaller the hole, the greater the chance of the hernia obstructing and strangulating
72
Describe the loss of blood supply in a strangulated hernia.
- first venous return stops
- bowel becomes oedematous as blood still coming in but cannot leave
- then arterial supply stops which causes ischaemic bowel
73
What is a Richter's hernia?
- not all hernias are associated with obstruction
- this is a knuckle of bowel getting caught in a hernia, but there is still continuity of bowel
- you still have some dead bowel but without proper bowel obstruction
74
What are the two types of investigations done for bowel obstruction?
- bloods
- imaging
75
What bloods are done for bowel obstruction and what would we see? (4)
- WCC/CRP - usually normal (if raised, suspicion of strangulation/perforation)
- U&E - electrolyte imbalance e.g. vomiting
- VBG if vomiting - hypoCl-, hypoK+ metabolic alkalosis
- VBG if strangulation - metabolic acidosis (lactate)
76
What imaging modalities are done for bowel obstruction? (2)
- erect CXR / AXR
- CT abdo/pelvis
77
What do we see in erect CXR/AXR for small bowel obstruction?
- ladder pattern of dilated small bowel loops >3cm proximal to the obstruction (central position)
- striations that pass completely across the width of the distended loop produced by circular mucosal folds
78
What do we see in erect CXR/AXR for large bowel obstruction?
- dilated large bowel >6cm (if caecum >9cm), tends to lie predominantly peripherally
- show haustrations of taenia coli that do not extend across the whole width of the bowel
79
Why do we do CT pelvis/abdo for bowel obstruction? (5)
- can see transition point (helps with surgery)
- can see dilatation of proximal loops - give IV or oral contrast if possible
- can localise site of obstruction
- can detect obstructing lesions and colonic tumours
- may diagnose unusual hernias (e.g. obturator hernia)
80
When can we do supportive/conservative treatment for patients with bowel obstruction?
When they have no signs of ischaemia / clinical deterioration
81
What supportive management is there for bowel obstruction? (4)
- NBM, IV peripheral access with large bore cannula - IV fluid resuscitation
- IV analgesia, IV antiemetics, correction of electrolyte imbalances
- NG tube for decompression (also removes problem of aspiration pneumonia), urinary catheter for monitoring output
- introduce gradual food intake if abdominal pain and distension improve
82
What conservative treatment is there for bowel obstruction? (3)
- faecal impaction - stool evacuation (manual, enemas, endoscopic)
- sigmoid volvulus - rigid sigmoidoscopic decompression
- small bowel obstruction - oral gastrograffin (highly osmolar iodinated contrast agent) can be used to resolve adhesional small bowel obstruction
- when you have small bowel adhesion the more fluid you pump in the more it twists so if you decompress and suck fluid out it has a chance to straighten itself out
83
What are the indications for surgical management of bowel obstruction? (4)
- haemodynamic instability or signs of sepsis
- complete bowel obstruction with signs of ischaemia
- closed loop obstruction (intervene before ischaemic)
- persistent bowel obstruction >2 days despite conservative management
84
What operations are there for bowel obstruction? (3)
- exploratory laparotomy/laparoscopy
- restoration of intestinal transit (depending on intra-operational findings)
- bowel resection with primary anastomosis or temporary/permanent stoma formation
85
What do we do with patients with bowel obstruction that are unwell, especially those with tumours?
Endoscopic stenting (especially if distal obstruction)
86
How do patients with GI perforation present? (6)
- sudden onset severe abdominal pain associated with distention
- pain aggravated by movement (lie very still)
- diffuse abdominal guarding, rigidity, rebound tenderness
- nausea, vomiting, absolute constipation (ileus of chemical irritation)
- fever, tachycardia, tachypnoea, hypotension
- decreased or absent bowel sounds
87
What are the four causes/types of GI perforation?
- perforated peptic ulcer
- perforated diverticulum
- perforated appendix
- perforated malignancy
88
How does perforated peptic ulcer present? (3)
- sudden epigastric or diffuse pain
- referred shoulder pain (phrenic nerve innervates diaphragm and right shoulder)
- Hx of NSAIDs, steroids, recurrent epigastric pain
89
How does perforated diverticulum present? (2)
- LLQ pain (insidious onset)
- constipation
90
How does perforated appendix present? (3)
- migratory pain
- anorexia
- gradual worsening RLQ pain
91
How does perforated malignancy present? (4)
- change in bowel habit
- weight loss
- anorexia
- PR bleeding
92
What are the two types of investigations we do for GI perforation?
- bloods
- imaging
93
What bloods do we do for GI perforation and what would we see? (3)
- FBC - neutrophilic leukocytosis
- possible elevation of urea and creatinine
- VBG - lactic acidosis
94
What imaging do we do for GI perforation? (2)
- erect CXR - subdiaphragmatic free air (pneumoperitoneum) = perforation!!
- CT abdo/pelvis - pneumoperitoneum, free GI content, localised mesenteric fat stranding, can exclude common differentials like pancreatitis
95
What differentials are there with the same symptoms as GI perforation? (4)
- acute cholecystitis
- acute pancreatitis
- acute appendicitis
- MI
96
What supportive management (on presentation) is there for GI perforation? (6)
- NBM and NG tube
- IV peripheral access with large bore cannula - IV fluid resuscitation
- broad spectrum Abx
- IV PPIs
- parenteral analgesia & antiemetics
- urinary catheter
97
Which patients with GI perforation do we do conservative management in?
In patients with localised peritonitis without signs of sepsis - very rare, most patients will need surgery
98
What conservative management is there for GI perforation? (2)
- interventional radiography (IR) - guided drainage of intra-abdominal collection
- serial abdominal exams and abdominal imaging for assessment to look at changes
99
What patients with GI perforation do we do surgical management in?
Patients with generalised peritonitis +/- signs of sepsis
100
What surgical management options are there for GI perforation? (6)
- exploratory laparotomy/laparoscopy
- primary closure of perforation +/- omental patch (most common in perforated peptic ulcer)
- resection of the perforated segment of the bowel with primary anastomosis or temporary stoma
- obtain intra-abdominal fluid for MC&S, peritoneal lavage ++++
- if perforated appendix - lap or open appendicectomy
- if malignancy - intra-operative biopsies if possible
101
What are the symptoms of biliary colic? (2)
- post prandial RUQ pain with radiation to shoulder
- nausea
102
What are the investigations for biliary colic? (2)
- normal blood results
- USS - cholelithiasis
103
What is the management for biliary colic? (2)
- conservative - analgesia, anti-emetics, spasmolytics
- follow up for elective cholecystectomy
104
What are the symptoms of acute cholecystitis? (3)
- acute, severe RUQ pain
- fever
- Murphy's sign
105
What are the investigations for acute cholecystitis? (2)
- elevated WCC/CRP
- USS - thickened gallbladder wall
106
What is the management for acute cholecystitis? (2)
- fluids, Abx, analgesia, blood cultures
- early (<72h) or elective cholecystectomy (4-6 weeks)
107
What are the symptoms of acute cholangitis?
| Stone --> CBD (blocks liver outflow)
Charcot's triad - jaundice, RUQ pain, fever
108
What are the investigations for acute cholangitis? (2)
- elevated LFTs, WCC, CRP, blood MC&S (+ve)
- USS - biliary dilatation
109
What is the management for acute cholangitis? (2)
- fluids, IV Abx, analgesia
- ERCP (within 72h) for clearance of bile duct or stenting
110
What are the symptoms of acute pancreatitis? (3)
- severe epigastric pain radiating to the back
- nausea +/- vomiting
- Hx of gallstones or alcohol use
111
What are the investigations for acute pancreatitis? (3)
- raised amylase/lipase
- high WCC/low Ca2+
- CT and US to assess for complications/cause
112
What is the management for acute pancreatitis? (4)
- admission score (Glasgow-Imrie)
- aggressive fluid resuscitation, O2
- analgesia, antiemetics
- ITU/HDU involvement
113
What are the two commonest causes of small bowel obstruction?
- previous abdominal operation
- strangulated external hernia
114
What is obstruction of small bowel usually accompanied by (compared to large bowel)?
Early and profuse vomiting (tends to be late or absent in large bowel obstruction)
115
What is a feature of large bowel obstruction that may not be present in small bowel obstruction?
Grossly distended abdomen due to size of the large bowel therefore distension is usually marked
116
What appearances on chest X-ray are typical of volvulus of the sigmoid colon? (2)
- enormously distended oval gas shadow, looped on itself to give typical 'bent inner-tube sign' or 'coffee bean sign'
- haustrae do not extend across the width of the gas shadow, suggesting large intestine
117
What conservative management is effective in treating the majority of patients with a sigmoid volvulus?
- a sigmoidoscope is passed with the patient lying in the left lateral position
- a large, well lubricated, soft rubber rectal tube is passed along the sigmoidoscope
- this usually untwists the volvulus, with release of vast quantities of flatus and liquid faeces
118
What is the risk of leaving sigmoid volvulus untreated?
The loop of sigmoid, with its blood supply cut off by torsion, can undergo necrosis
119
For sigmoid volvulus, what is the next step if a flatus tube fails?
Exploratory laparotomy and sigmoid colectomy with end colostomy (Hartmann's procedure)
120
What in the history/exam can indicate acute mesenteric ischaemia? (7)
- elderly patient who is an ex-smoker (increased risk of CVD)
- short history (e.g. 1 day Hx)
- central pain with guarding
- no previous abdominal scar or hernia
- no bowel sounds
- poor general condition
- increased serum lactate
121
What can CTAP with contrast show in acute mesenteric ischaemia? (3)
- thrombus in mesenteric arteries and veins (normal flow white, thrombus grey)
- abnormal enhancement of bowel wall
- presence of embolus or infarction of other organs
122
How would you manage a patient with acute mesenteric ischaemia and what are the goals of this?
Emergency exploratory laparotomy
- restoration of SMA blood flow
- resection of non-viable bowel
123
What is done in an exploratory laparotomy for acute mesenteric ischaemia?
- midline incision
- evaluate the abdominal viscera
- if obvious intestinal necrosis - resection of the affected bowel loops
124
What is done in a damage control laparotomy for acute mesenteric ischaemia?
- stapled off bowel ends may be left in discontinuity
- re-inspect after a period of continued ICU resuscitation to restore physiological balance
125
How do we restore blood flow to the SMA in acute mesenteric ischaemia? (3)
- embolectomy of SMA - in embolic AMI
- endovascular management of SMA thrombus - in thrombotic AMI
- arterial bypass of SMA - in thrombotic AMI
126
What are the arterial causes of acute mesenteric ischaemia? (3 main types)
- embolism (50%) - sources:
- from left auricle - atrial fibrillation
- mural infarct
- atheroma from aorta or aneurysm
- endocarditis vegetations
- left atrial myxoma
- thrombosis (20-35%)
- blocks origin of SMA and can cause ischaemia of full length of small bowel
- due to atherosclerosis - often all main splanchnic vessels - coeliac, superior and inferior mesenteric arteries
- nonocclusive (<5%)
- due to hypotension/hypoperfusion
- due to vasospasm in shock --> nonocclusive mesenteric ischaemia (NOMI)
- critically ill patients with vasopressor requirements
- those undergoing dialysis with large volume fluid removal
127
What are the venous causes of acute mesenteric ischaemia?
Superior mesenteric vein thrombosis:
- occurs in patients with:
- portal hypertension
- portal pyaemia
- sickle cell disease
- related to the presence of an underlying hypercoagulable state
128
What is portal pyaemia (pylephlebitis)?
- form of septic (often suppurative) thrombophlebitis of the portal venous system
- complication of intra-abdominal sepsis
- diverticulitis
- appendicitis
