Gen Surg: Intestinal obstruction Flashcards
(96 cards)
1
Q
What is the definition of intestinal obstruction?
A
Failure of downward passage of intestinal contents
2
Q
What is meant by dynamic intestinal obstruction?
A
There is increasing peristalsis working against an obstructing agent
3
Q
What is adynamic intestinal obstruction?
A
Peristalsis is absent or ineffective and there are no effective propulsive waves
4
Q
What is a simple obstruction?
A
Obstruction of the intestinal lumen without interference with its blodd supply
5
Q
What happens above/below the site of obstruction in someone with a simple obstruction?
A
Peristalsis + distention (due to gas, GI content and fluid build up)
Below the obstruction - collapsed, immobile, pale
@ obstruction = perforation can occur
6
Q
What are causes of death in simple bowel obstruction?
A
- Fluid & electrolyte imbalance - from third space loss and dehydration
- Peritonitis - proliferation of bacteria proximal to obstruction leading to bacterial translocation
7
Q
Causes of simple bowel obstruction
A
Inside the lumen - gallstones, impaced faeces
In the wall - strictures, tumours, CD, diverticulitis
Outside the wall - ADHESIONS, hernias
8
Q
What is strangulation?
A
Intestinal obstruction with persistent interference of the blood supply
9
Q
What are causes of intestinal strangulation?
A
- Strangulated hernia
- Intussuception
- Adhesive intestinal obstruciton
- Volvulus
- Vascular occlusions
10
Q
What are the pathophysiological consequences of strangulation?
A
- Venous return is impaired - venous supply lower pressure than arterial supply, strangulated bowel and its mesentery look congested
- Serosanguinous fluid formation - accumulated inside the peritoneal cavity
- Arterial supply is impaired - colour of the affected segment becomes black
11
Q
When would you suspect strangulation?
A
Internal strangulation
- Severe pain thats never completely absent between attacks
- Shock
- Tenderness and rigidity with rebound tenderness
- GI suction fails to releive pain
Strangulated external hernia
- Hernia swelling that is tense, tender, irreducible and no expansable impulse on cough (hernias are painless unless complicated)
12
Q
What are causes of death in strangulation?
A
- Peritonitis due to perforation - bacterial translocation and impairment of barrier function of intestinal mucosa
- Hypovolaemic shock - third space loss
- Sepsis
13
Q
What is a closed loop obstruction?
A
When some part of the gut is closed at both ends - THIS IS DANGEROUS AND IS A SURGICAL EMERGENCY eg competant ileocaecal valve
14
Q
What is typically the cause of a closed loop obstruction
A
Sigmoid volvus
15
Q
At what diameter would you be concerned of caecal perforation?
A
10cm
16
Q
What are the complications of bowel obstruction?
A
- SEPSIS - venous compression, bowel cells die, decreased peristalsis, bacteria enter circulation
- SHOCK (hypotension) - venous compression, fluid secretion, decreased H2O, decreased electrolytes, hypotension
- SHOCK (hypovolaemia) - bowel distension, decreased vomitting response, decreased H2O, decreased fluids
Bowel ischaemia from venous compression
Perforation due to increased air
Sepsis due to perofation/dissemination
17
Q
What are causes of small bowel obstruction?
A
- Adhesions
- Hernias
- Malignant tumours
- Crohn’s disease
- Intussusception
- Gallstone ileus
- Paralytic ileus
- Miscellaneous (bezoars)
18
Q
What is the most common cause of small bowel obstruction?
A
Adhesions
19
Q
What are abdominal adhesions?
A
Adhesions are bands of ‘scar’ tissue in various degrees of development. They are part of a normal intra-abdominal repair process following a variety of insults - handling of bowel, contact of internal organs with foreign objects, cuts involving internal organs.
Can also result from appendix rupture, infection, radiation, abdo infections
20
Q
Indications for surgery in adhesive intestinal obstruction
A
Suspected strangulation
Failure of conservative management
21
Q
What is the pathophysiology behind abdominal adhesion formation?
A
Peritoneum is ‘injured’ -> reparative process similar to that seen following the formation or in prevention of a thrombus.
22
Q
What types of internal hernias can occur which can lead to small bowel obstruction?
A
- Paraduodenal
- Transmesocolic
- Transmesenteric
- Omental
- Retroanastomotic - bowel is trapped behind a surgical anastomosis
23
Q
What types of benign tumours of the small intestine can cause SBO?
A
- Hyperplastic polyps
- Lipomas
- Adenomas - including Peutz-Jeghers polyps
- G/I stromal tumors
- Hemangiomas
24
Q
What secondary malignancies can present as SBO?
A
- Ovarian
- Stomach
- Pancreas
- Colonic
- Malignant melanoma
- Lung
- Breast
25
How can crohn's disease lead to SBO?
Can cause strictures. May also have adhesions from previous surgeries
26
What is paralytic ileus?
Cessation of peristalsis due to failure of neuromuscular mechanism of the intestine causing accumulation of fluid and gas in the intestine
27
What are causes of paralytic ileus?
* **Post surgery especially for peritoneal sepsis**
* **Peritonitis**
* **Drugs** - TCAs, anticholinergic, opiod mets
* **Spinal injury**
* **Electrolyte imbalance** - hypokalaemia, hyponatraemia, uraemia (esp magnesium and potassium\_
* **Extensive handling of the bowel at operation**
28
How does paralytic ileus increase the risk of adhesion formation?
* **Intestinal segments have more prolonged contact, which allows fibrous adhesions to form**
* **Intestinal distention causes serosal injury and ischemia**
29
Presentation paralytic ileus
Progressive abdo distension, vominting, absolute constipation, failure to pass flatus.
Mild abdo discomfort.
30
Management paralytic ileus
TREAT UNDERLYING CAUSE
Gi suction
Restore fluid and electrolyte balance, monitor for AKI
Encourage mobilisation
31
What are the pathophysiological consequences of small bowel obstruction?
* **Proximal dilatation of intestine** - due to accumulation of GI secretions and swallowed air
* **Stimulation of columnar cell secretory activity -** increase in intra-lumenal fluid
* **Increased peristalsis** **above and below the obstruction** -
* **Early frequent loose stools and flatus**
* **Increased intraluminal pressure**
32
What is the result of small bowel obstruction in terms of fluid balance?
**Hypovolaemia** - due to:
1. **Compression of mucosal lymphatics** -\> lymphoedema of the bowel wall
2. **High intraluminal hydrostatic pressures** -\> increased hydrostatic pressure in the capillary beds
3. **Massive loss into the third space** - fluid, electrolytes, and proteins (into lumen)
4. **Vomiting + loss of normal fluid intake**
33
How does intestinal obstruction affect intestinal flora?
* **Proliferation proximal to obstruction**
* **Microvascular changes in bowel wall -\> Translocation of bacteria to mesenteric lymph nodes**
* **Resultant bacteraemia**
34
What are symptoms of small bowel obstruction?
* **Pain**
* Peristaltic pain
* Colicky initially, constant suggests strangulation/impending perforation
* **Vomiting**
* **Abdominal distention**
* ****Jejunal obstruction - minimal
* Ileal obstruction - central
* **Absolute constipation** - late symptom
35
What are signs of SBO?
* **Features on inpection** - surgical scars, visible peristalsis
* **Dehydration/Signs of shock**
* **Abdominal distention**
* **Bowel sounds**
* **Increased/borborygmus** - early dynamic
* **Decreased/absent** - paralytic and late mechanical
* **May have** **s****igns of peritonism**
* **Empty rectum on PR**
* **May have herniation** - non-reducible
Focal tenderness, guarding, rebound tenderness when ischaemic
36
What are the characteristic features of abdominal pain in intestinal obstruction?
**Generalized abdominal colicky pain** - Each attack lasts for few minuets then gradually disappears, with periouds of relief in between
37
When is distention less prominent in SBO?
When the obstruction is more proximal
38
When is distention more prominent in SBO?
In distal obstruction
39
How does the timing of vomiting roughly indicate where a SBO might be?
The more proximal the obstruction, the earlier vomiting will occur:
* **Jejunal Obstruction -** Vomiting occurs with the first and each attack of pain
* **Ileal Obstruction** - Vomiting is delayed for few hours; then it occurs with each attack of pain
40
If vomiting occured early on in someone with suspected SBO, what might this suggest about where the problem is in the small intestine?
**High** - e.g. jejunal obstruction
41
If feculent vomiting occured late after someone presented with abdominal pain and marked abdominal distention, where might you suspect the obstruction is occuring?
Low - e.g. ileum
42
If someone had jejunal obstruction, how distended would their abdomen be?
Minimally distended
43
If someone had ileal obstruction, how much abdominal distention might they have?
Prominent ***_central_*** distention
44
If someone had distention of the flanks, what might this indicate about where the obstruction is occuring?
**Colonic distention only** - LBO with competent ileocaecal valve
45
If someone had generalised distention of the abdomen, what might this indicate as to where the obstruction is occuring?
**Distended small bowel & colon -** LBO with incompetent ileocaecal valve
46
What featuress would make you think that someone had a stangulated obstruction?
* **Pain** - more severe and never completely absent in between the attacks
* **Shock -** usually present and progressive
* **Tenderness & Rigidity -** Localized tenderness & rebound tenderness
* **Tense, tender, irreducible, non-expansile external hernia**
47
What are some causes of intestinal obstruction without absolute constipation?
* **Richter's hernia**
* ****Involves bowel wall only
* Strangulation without obstruction
* **Gallstone ileus**
* **Mesenteric vascular occlusion**
* **Pelvic abscess causing obstruction**
48
What is gallstone ileus
GS impaction at terminal ileum.
Repeated/ongoing inflammation makes walls of gallbladder oedematous so it adheres to duodenum (most commpnly) and fistula forms. Some gallstones pass fine but the big ones can get stuck in terminal ileum or ileocaecal valve (mechanical obstruction).
49
Diagnosis of gallstone ileus
Rigler's triad - penumobila (air in bile ducts), evidence SBO, gallstone outside gallbladder
50
What are symptoms of LBO?
* **Absolute constipation**
* **Lower abdominal pain**
* ****Flanks - colonic distension only, LBO with incompetant ileo-caecal valve
* Generalised - distended small bowel and colon, LBO with incompetent ileo-caecal valve
* **Vomiting a late manifestation**
* **Features of ischaemia/strangulation**
* Acute toxicity
* Fever
* Chills
* Hypotension
* Confusion
51
What signs can occur in LBO?
* **Features on inpection** - surgical scars, visible peristalsis, "step-ladder" appearance due to distended loops over each other
* **Dehydration/Signs of shock**
* **Abdominal distention** - Flanks/generalised
* **Abdominal Mass**
* **Bowel sounds**
* **Increased/borborygmus** - early dynamic
* **Decreased/absent** - paralytic and late mechanical
* **May have signs of peritonism**
* **Tender LIF** - diverticular disease
* **Tender RIF** **+/- mass** - impending ischaemia
* NO TENDERNESS or rigidity with simple obstruction (strangulation)
* Focal tenderness, guarding, rebound tenderness with ischaemia
* **PR** - rectal mass, blood, mucus
* **May have herniation** - non-reducible
52
What are the 2 most common causes of SBO?
Adhesions and hernias
53
What are causes of large bowel obstruction?
* **_Colon cancer_**
* **Constipation**
* **Diverticular stricture**
* **Volvulus**
54
What investigations would you perform if you suspected intestinal obstruction?
* **Bedside**
* NEWS score,
* Fluid status
* Urine output
* **Bloods**
* FBC (low Hb? anaemia suspect colon cancer) (raised WCC? occurs early on in strangulation - bacterial translocation),
* U+E's (dehydration due to 3rd space loss, electrolye imbalance),
* LFTs (mets?),
* consider ABG (high lactate eg ischaemia)
* CRP
* G+S
* Calcium and TFTs to exclude pseudo-obstruction
* **Imaging** - AXR, Erect CXR, Gastrografin follow through/enema (LBO), Consider CT
55
What might you see on AXR in someone with suspected small bowel obstruction?
* **Dilated loops proximal to the obstruction** - predominantly central dilated loops
* **Valvulae conniventes are visible**
* **Air-fluid levels if the study is erect**
* **Gasless bowel**
* **Partial:** gas throughout the abdomen and into the rectum.
* **Complete:** no distal gas, and staggered air-fluid levels.
56
What might you see on CXR in someone with an intestinal obstruction?
**Free air** **under the diaphragm** - due to perforation
57
What is important to include in your examination of someone with features of intestinal obstruction?
PR and hernial orifice exam
58
What is a gastrografin follow through study?
Involves administration of contrast material into the stomach. The subsequent assessment of degree of passage of this material, using serial x-rays, can provide information regarding the presence and location of the obstruction within the GI tract:
* **Partial SBO** - medium passes into rectum.
* **Complete SBO** - medium does not pass into rectum and is held up at site of obstruction.
Not done in acute presentations.
59
What might you find on U+E's in someone with bowel obstruction?
* **Electrolyte imbalance** - hyponatraemia, hypokalaemia
* **Hyperuraemia** - Renal failure
60
What might you use a gastrografin enema to look for?
Lower bowel obstruction
61
What might you use a CT to look for in the context of bowel obstruction?
* **Confirm the diagnosis if transition point is seen**
* **Identify the level (SBO/LBO)**
* **Find the cause**
* **Staging in obstruction secondary to malignancy**
62
What are causes of obstruction in newborn babies?
* **Imperforate anus**
* **Congenital atresia/stenosis of the gut**
* **Volvulus**
63
What is the most common cause of obstruction in a child age 3-12 months old?
Intussuception
64
Causes of intussusception in adults
Polyp
Submucous lipoma
Polypoidal tumours
Inverted merckel's diverticulum
65
Presentation intussusception chidlren
Recurrent episodes of screaming and drawin up of legs
Bilious vomiting
Redcurrent jelly stools
Sausage shaped mass
Most common @ ileocaecal valve
66
How would you manage someone with complete/complicated/stangulated SBO?
* **ABCDE** - give 100% oxygen
* **NBM**
* **NG decompression (and to stop vomiting/prevent aspiration)**
* **IV fluids - aggressive as pateint may be very dehydrated**
* **Catheterise**
* **Analgesia**
* **Investigations** - AXR, erect CXR, Bloods, monitoring/fluid status
* **Surgery/Emergency surgery** - laparoscopy
* Stangulation is an emergency
67
What are indications for early surgery in bowel obstruction?
* **Obstructed hernia**
* **Suspected strangulation**
* **Small bowel obstruction in a ‘virgin abdomen’**
* **Failure of conservative Rx in adhesive SBO (up to 72hr)**
* **Obstructing tumours on CT**
68
How would you manage someone with complete/complicated/stangulation obstruction who wasn't fit for surgery?
* **ABCDE**
* **NG decompression + fluid resus**
* **Antiemetics**
* **Antispasmodics**
69
How would you manage partial SBO?
* **ABCDE**
* **NG decompression**
* **IV fluid resus**
* **Analgesia**
* **Anti-emetics**
* **Consider surgery if not resolved within 48-72 hrs**
70
What are the differences in radiological appearence of the jejunum, ileum and colon?
71
How would you treat intussusception in an adult?
Laparotomy - resection +/- anastamosis
72
What is volvus?
A loop of intestine around its mesentery, resulting in a closed loop bowel obstruction. Affected bowel can become ischaemic due to compromised blood supply, rapidly leading to necrosis and perforation
73
What are the different types of volvulus that can occur?
* **Volvulus neonatorum**
* **Volvulus of small intestine**
* **Caecal volvulus**
* **Sigmoid volvulus**
74
Why is sigmoid volvus the most common volvus?
It has a v long mesentery
75
Risk factors for development of volvus
Neuropsychaitric disorders
Laxative abuse
Male gender
DM
Increased age **(especially common elderly male)**
Chronic constipation
Previous abdo surgery
76
What are features of a sigmoid volvulus?
* **Sudden left sided abdo pain**
* **Adbo distention**
* **Absolute constipation**
**(signs of bowel obstruction)**
77
What sign is seen on xray in sigmoid volvus?
Coffee bean sign
78
How would you manage a sigmoid volvulus?
* **General management**
* **+ decompression with sigmoidoscopy**
* **Surgery** (if _repeated failed attempts at decompression_, _necrotic bowel_ noted, suspected/proven _peritonitis_)
* **Emergency:** Untwisting by flexible sigmoidoscopy -\> Sigmoid resection in fit patients
* **Failed sigmoidoscopy** -\> open surgery
* Primary anstomoses OR hartmans
79
If someone was found to have a large bowel obstruction on AXR, what investigation would you consider doing next?
Gastrografin enema - determine whether carcinoma, ogilives syndrome or diverticular disease
80
If someone was found to have free gas under the abdomen on AXR, How would you manage them?
Surgery
81
What are contraindications for primary anastamosis?
* **Poor bowel preparation (on-table lavage \*may be indicated)**
* **Friable bowel**
* **Circulatory instability**
* **Synchronous or multiple tumours\*\***
* **Peritonitis present**
* **Immunocompromised patient**
* **Previous radiation (often pelvic)**
* **Pelvic abscess present (debatable)**
82
What is OGilvie syndrome?
**Clinical syndrome with symptoms, signs & AXR appearance of LBO but with no identifiable mechanical obstruction**
Thought to be an interruption of autonmic nervous system to colon, resulting in absense of smooth muscle action in bowel wall
83
What are predisposing factors to developing Ogilivie syndrome?
* **Puerperium**
* **Electrolyte imbalance**
* **Pelvic surgery**
* **Trauma**
* **Malignancy**
* **Cardiorespiratory disorder**
* **Neurological disorder**
* **Systemic infection**
* **Medications**
* **Opiods**
* **Calcium channel blockers**
* **Antidepressants**
84
How do individuals with Ogilvie syndrome present?
With features of mechanical bowel obstruction
85
How would you manage Ogilvie syndrome?
* **Neostigmine - inhibits cholinesterase**
* **Colonoscopic decompression**
86
What are the key things that you need to establish in suspected bowel obstruction?
1. **Is it small or large bowel?**
2. **Is it dynamic/adynamic (ileus vs mechanical)?**
3. **Is it simple/closed loop/strangulated?**
87
What is the cardinal sign of a strangulated obstruction?
Peristonism
88
What is the pathophysiology of Ogilvie's syndrome?
Most likely caused by a disturbance of the autonomic nervous system:
* **Reflex sympathetic stimulation inhibiting colon and/or**
* **Interruption of parasympathetic influence of S2-S4**
This leads to colonic dilatation and colonic atony
89
What mnemonic can be used to remember the main symptoms of obstruction?
PV D+C
* **P**ain
* **V**omiting
* **D**istention
* **C**onstipation
90
What mnemonic can be used to remember the causes of small bowel obstruction?
SHAVIT
* **S**tones (gall stone ileus )
* **H**ernias (always examine hernial orifices!)
* **A**dhesions (can occur very early and very late after surgery)
* **V**olvulus
* **I**ntusssusception / IBD
* **T**umour (1º adenocarcinomas rare in small bowel)
\*\*Adhesions and hernias are the commonest causes of small bowel obstruction and should be considered before more unusual causes.
91
Describe causes of bowel obstruction in terms of intraluminal, mural, extramural
Intraluminal
* Gallstone ileus
* Foreign body
* Faecal impaction
Mural
* Carcinoma,
* Inflammatory strictures
* Intussusception
* Diverticular strictures
* Meckles diverticulum
* Lymphoma
Extramural
* Hernias
* Adhesions
* Periteoneal masses
* Volvus
92
What is mesenteric vascular occlusion?
Occlusion of the superior mesenteric or one of it's branches
93
Risk factors for mesenteric vascular occlusion
**Arterial embolism - AF**, SBE
Arterial thrombosis - PCV, atherosclerosis, OCP
Venous thrombosis - **PHT**
MORE COMMON IN ELDERLY
94
Presentation mesenteric vascular occlusion
* **Generalised abdo pain** that is **_out of proportion to physical signs_**.
* N+V
* Shock
* Abdo tenderness/rigidity
95
What is seen on abdo xray in mesenteric vascular occlusion?
Thumb-printing sign
96
Managment of mesenteric vascular occlusion
Early - embolectomy (preferably though angioplasty)
Late - bowel resection and anastomosis, managed in ICU
