Bowel Obstructions Flashcards by Neil Srivastava

Define intestinal obstruction

Arrest/Blockage on onward propulsion of intestinal contents

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How are obstructions classified (4)

According to site (Large bowel/small/gastric)
Extent of luminal obstruction (partial or complete)
According to mechanism (mechanical/true/functional)
According to pathology (simple, closed loop, strangulation or intussusception)

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What usually causes a complete luminal obstruction

Volvulus = resulting in overflow and sickness

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What is true mechanism of intestinal obstruction

INtraluminal or extraluminal obstruction

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Give an example of a functional bowel obstruction

Dynamic bowel due to the absence of normal peristaltic contractions, caused by abdo surgery or acute pancreatitis

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What is intussusception

Part of an intestine folds into the next section of bowel

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What tumours can cause obstruction of the lumen

Carcinoma

2. Lymphoma

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What is diaphragm disease

Formation of thin-walled strictures which narrow the lumen into a ‘pinpoint’

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What usually causes diaphragm disease

NSAIDs

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What is Meconium ileum

Content of bowel is sticky = blockage

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What is gallstone ileum

Gallstone within lumen of small bowel

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What inflammatory disease can cause bowel obstruction

Crohn’s disease

2. Diverticulitis

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Where does diveritulitis occur

Sigmoid colon

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What is diverticulitis

Inflammation of the pouches (diverticula) in the large intestines

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Where do diverticulas form

Where blood vessels penetrate

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Describe how a diverticula forms

In low fibre diets, colon tries to push harder to move things alone increasing pressure
Pressure increase pushes mucosa through gaps = diverticula (outpouching)
They get inflamed or burst

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Consequences of diverticulitis (what conditions can it cause in the long-term)

Acute peritonitis

2. Possible death

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What neural disease can cause bowel obstruction

Hirschsprung’s disease

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What is Hirschsprung’s disease

In babies - no complete innervation of colon to rectum

Causes gut dilatation and filling of faeces which remains since no ganglion cells do peristalsis (obstruction)

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How do adhesions cause bowel obstructions

Sticking together of abdo structures to one another (e.g. bowel loops, omentums, other solid organs by fibrous tissues)

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What is the most common cause of obstruction in adults

Adhesions

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When are adhesions common

After surgery

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How does adhesion cause obstruction

Usually free-moving intestines

When movement is limited by fibrous tissue, intestine can twist on themselves occluding blood supply or peristaltic movement

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What kind of obstruction is a volvulus

Closed loop bowel

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What carcinoma causes peritoneal tumours to form

Ovarian carcinomas

What are signs of any bowel obstructions

Tinkling bowel sounds Tympanic percussion

What usually causes SMALL BOWEL obstruction

A previous surgery OR Crohn's disease

Main mechanisms that cause SBO

1. ADHESIONS 2. Hernias Any mechanical obstructions

What surgeries in particular will cause adhesions and thus small bowel obstructions

Pelvic, gyro and colorectal surgery

Long-term effect of hernias on the GI tract

STRANGULATION

How does obstruction effect the small bowel

1. Bowel distension above block 2. Increased secretion of fluid into distended bowel Proximal dilatation above block: 1. Increased secretions and swallowed air into small bowel 2. More dilatation results in decreased absorption and mucosal wall oedema 3. Increased pressure with the intramural vessels becoming compressed resulting in ischaemia or perforation

What happens if small bowel disease is left untreated

1. Ischaemia 2. Necrosis 3. Perforation

Clinical presentation of SBO

1. Pain (colicky) then pain becomes higher in abdomen than in LBO 2. Vomiting following pain (occurs earlier in SBO than LBO) 3. Less distention to LBO 4. Nausea + anorexia 5. Tenderness suggests strangulation and urgent surgery is required 6. Constipation with no passage of wind 7. Increased bowel sounds

Four diagnostics for SBO

1. Abdo X-ray 2. Examination of hernia orifices and rectum 3. FBC 5. GOLD STANDARD - CT

What does a CT show in SBO

Localise lesions

Role of AXR in SBO

1. Shows central gas shadows that completely cross the lumen and no gas in the large bowel 2. Distended loops of bowel proximal to obstruction 3. Fluid levels seen

How is SBo treated

1. Fluid resus 2. Bowel decompression 3. Analgesia and antiemetic 4. Antibiotics 5. Surgery (remove obstruction via laparotomy)

What are antiemetics

Treat vomiting and nausea

How long does it take for LBOs to present

5 days until symptoms occur as it has a larger lumen

Why does it take a while for symptoms to occur and why is it rare for LBOs to occur

1. Larger lumen | 2. Circular and longitudinal muscles all large bowel to distend much greater

What usually causes LBO

Colorectal malignancies rarely volvulus

What part of the colon dilates in LBO

The colon proximal to obstruction dilates

How does this effect blood flow and colonic pressure in LBO (dilatation)

Increases colonic pressure Decreased mesenteric blood flow = mucosal oedema

What is mucosal oedema

Transudation of fluid and electrolytes from the lumen

How can dilatation of the LBO effect arterial blood supply

Mucosal oedema caused can ischaem the arteries and cause mucosal ulceration

Result on mucosal ulceration on GI

Full thickness necrosis and perforation

How does sepsis effect the GI tract i LBO

Bacterial translocation

What happens in a colonic volvulus

1. There is axis rotation based of mesentery and a 360 degree twist resulting in a closed loop obstruction

How does a colonic volvus effect pressure/blood flow and contents of the GI tract in LBO

1. Fluid and electrolytes shift into closed loop 2. Increased pressure and tension in the loop causes impaired colonic blood flow 3. Ischaemia, necrosis and perforation of the bowel loop soon follows if untreated

CLinical presenttation of LBO

1. Abdo pain 2. Abdo distention 3. Bowel sounds normal than increased then quiet later 3. Palpable mass 4. Late vomiting (faecal-like) 5. Constipation 6. Fulllness/bloating/Nausea

How to diagnose LBO

1. Digital rectal exam 2. FBCs 3. AXR 4. CT

What do we look for in a digital rectal exam for LBO

1. Empty rectum 2. Hard stools 3. Blood

What would we look for in FBCs for LBO

Low Hb (Cause bloody stools)

What would AXR show for LBO

1. Peripheral gas shadows proximal to the blockage (in caecum not rectum) UNLESS PR examination is done 2. Distended caecum and ascending colon

How is LBO treated

1. Aggressive fluid resus 2. Bowel decompression 3. Analgesia + antiemetic 4. Antibiotics 5. Surgery (removes obstruction done by laparotomy (open surgery)

How are obstructions in the LBO due to malignancy treated

1. Colorectal stents followed by elective surgery

What is pseudo-obstruction

Mimics obstruction but with no mechanical cause

What usually causes pseudo-obstruction

1. Intra-abdominal trauma 2. Pelvic, spinal and femoral fractures 3. Postoperative states 4. Intra-abdominal sepsis 5. Pneumonia 6. Drugs (opiates) 7. Metabolic disorders

Clinical presentation of pseudo-obstruction

Progressive abdo distention and pain

How is pseudo-obstruction diagnosed

Gas-filled large bowel

How is pseudo-obstruction treated

Treat underlying problem IV NEOSTIGMINE (

What three types of bowel ischaemia are there

1. Acute mesenteric ischaemia 2. Chronic mesenteric ischaemia (intestinal angina) 3. Ischaemic colitis (Chronic colonic ischaemia)

What blood supplies the colon

1. Inferior superior mesenteric arteries

What are watershed areas

Splenic flexure | Caecum

What does AF with abdo pain indicate (conditions wise)

Mesenteric Ischaemia

What part of the GI tract is effected by acute mesenteric ischaemia

Small bowel

What is the most common cause of acute mesenteric ischaemia

Superior mesenteric artery thrombosis

How does AF cause acute mesenteric ischaemia

Superior mesenteric artery embolism

In which patients is mesentery vein thrombosis a cause for acute mesenteric ischaemia

Younger patients

What other factor causes acute mesenteric ischaemia

Non-occlusive diseases

Clinical presentation of acute mesenteric ischaemia

1. Acute severe abdo pain (constant, central at right iliac fossa) 2. No abdo signs 3. Rapid hypovolaemia resulting in shock

How is acute mesenteric ischaemia diagnosed

1. Bloods 2. AXR 3. Laparotomy 4. CT/MRI angiography

What would we see in blood tests for acute mesenteric ischaemia

Raised Hb due to plasma loss Raised WBC Persistent metabolic ACIDOSIS

What would we see in AXR for acute mesenteric ischaemia

1. Used to rule out other pathologies and gads-less abdomen

What is a laparotomy

1. Surgical procedure -> cut into abdo wall -> access abdo cavity

Why is a laparotomy used for acute mesenteric ischaemia

To make diagnosis See necrotic bowel

How is acute mesenteric ischaemia treated

1. Fluid resus 2. Antibiotics (IV GENTAMICIN + METRONIDAZOLE) 3. IV HEPARIN to reduce clotting 4. Surgery to remove dead bowel

Complications of treating acute mesenteric ischaemia

1. Septic peritonitis 2. Systemic inflammatory response syndrome progressing into a multi-organ dysfunction syndrome, mediated by bacteria translation across dying gut wall

What is chronic colonic ischaemia

Inflammation and injury of the large intestines due to inadequate blood supply

What causes chronic colonic ischaemia

``` Low BP Constriction of blood vessels Blood clot Thrombosis Emboli Decreased CO Drugs (vasopressin) Surgery Vasculitis (SLE) Coagulation disorders Idiopathic ```

Risk factors for chronic colonic ischaemia

Contraceptive pill Nicorandil drug Thrombophilia Vasculitis

What arteries tend to be occluded in chronic colonic ischaemia

1. Occlusion of branched superior mesenteric artery and inferior mesenteric artery

Clinical presentation of chronic colonic ischaemia

1. Sudden onset lower left side abdo pain 2. Passage of red blood with NO diarrhoea 3. Signs of shock

What are the signs of shock

1. Pale skin Weak rapid pusle 3. Reduce Urine output 4. Confusion

Differential diagnosis of chronic colonic ischaemia

Other causes of acute colitis

Diagnosis of chronic colonic ischaemia

1. Urgent CT scan to exclude perforation 2. Flexible sigmoidoscopy 3. Colonoscopy and BIOPSY (GOLD STANDARD) 4. Barium enema

What would flexible sigmoidoscopy show in chronic colonic ischaemia

1. Epithelial cell apoptosis

When is colonoscopy and biopsy done for chronic colonic ischaemia

1. After the patient has fully recovered to exclude stricture formation at the site of disease and confirm mucosal healing

What is barium enemia in chronic colonic ischaemia

Thumb printing of submucosal swelling at splenic flexure

How is chronic colonic ischaemia treated

1. Fluid replacement 2. Antibiotics 3. Gangrenous ischaemic colitis

Why are antibiotics given in chronic colonic ischaemia

To reduce infection risks due to translocation of bacteria across dying gut wall

Clinical presentation of GANGRENOUS ischaemic colitis

Peritonitis | Hypovolaemic shock

How is GANGRENOUS ischaemic colitis treated

1. Prompt resus | 2. Surgical resection of affected bowel and stoma formation

Bowel Obstructions Flashcards

(93 cards)