Intestinal Obstruction Flashcards by E Thomas

What is intestinal obstruction?

A blockage to the transit of intestinal contents through the gut

How well did you know this?

Not at all

Perfectly

What are the 3 categories of obstruction?

Intra-luminal
Intramural
Extra-luminal

How well did you know this?

Not at all

Perfectly

What are some causes of intra-luminal obstruction?

Tumours

Gallstones

Meconium disease: first stool of neonate can cause blockage

How well did you know this?

Not at all

Perfectly

What are some causes of intramural obstruction?

Inflammation can lead to fibrosis and therefore obstruction: Crohn’s or diverticulitis

Tumours within bowel wall

Neural: Hirschprung’s disease

How well did you know this?

Not at all

Perfectly

What is Hirschprung’s disease?

Neonates can be born without innervation all the way through the bowel.
They have an aganglionic segment of bowel

The faeces just doesn’t move down

How well did you know this?

Not at all

Perfectly

What are some extra-luminal causes of obstruction?

Adhesions

Volvulus: twist in bowel

Tumour in peritoneum can press on bowel obstructing it

How well did you know this?

Not at all

Perfectly

What are adhesions? Why do they occur?

They are when scar tissue forms between the wall of one segment of the bowel and the wall of another segment.

Two segments become attached when they shouldn’t be

Due to surgery usually

How well did you know this?

Not at all

Perfectly

How do adhesions cause obstruction?

They cause bits of the bowel to become twisted and trapped so faeces can’t travel through easily

How well did you know this?

Not at all

Perfectly

What type of cancer usually causes peritoneal tumours?

Ovarian

How well did you know this?

Not at all

Perfectly

What is a volvulus? And which part of the bowel are they common in?

A twist in the bowel

Parts of the colon that have a mesentery: sigmoid or caecum

How well did you know this?

Not at all

Perfectly

What’s the difference between mechanical and functional obstruction?

Mechanical: an actual obstruction, something is physically blocking bowel

Functional: paralysis or problem with nerves supplying bowel means no peristalsis so no movement of faeces

How well did you know this?

Not at all

Perfectly

What is a pseudo-obstruction?

Obstruction caused by something unknown

How well did you know this?

Not at all

Perfectly

What are the complications that can arise from untreated intestinal obstruction?

Ischaemia
Necrosis
Perforation

How well did you know this?

Not at all

Perfectly

What are the clinical features of intestinal obstruction?

Vomiting (different types depending on site of obstruction)

Colicky pain

Constipation or no faeces or flatus passed at all

Distention

Tenderness on pressure

Anorexia

Hypovolaemia

Tinkling bowel sounds

How well did you know this?

Not at all

Perfectly

What type of vomiting would you see with obstruction:

high up near stomach
in the colon?

Near stomach = projectile vomiting
It would occur sooner

In colon = faeculent vomiting
It would occur later

How well did you know this?

Not at all

Perfectly

What is meant by ‘proximal dilatation’?

The section of bowel just above the obstruction becomes dilated.

How well did you know this?

Not at all

Perfectly

Why does proximal dilation occur in the:

small bowel
large bowel?

Small bowel:
there’s a build up of secretions and swallowed air that can’t pass through

Large bowel:
bacterial fermentation releases gases that can’t escape

How well did you know this?

Not at all

Perfectly

Why does intestinal obstruction cause decreased blood volume?

The blockage causes fluid and electrolyte imbalance, leading to hypovolaemia

How well did you know this?

Not at all

Perfectly

What are the causes of small bowel obstruction (SBO) in adults?

Adhesions (due to past surgery)
Hernia (often incisional)
Crohn’s
Malignancy

How well did you know this?

Not at all

Perfectly

What are the causes of small bowel obstruction (SBO) in children?

Appendicitis

Developmental defects

How well did you know this?

Not at all

Perfectly

What types of surgery carry a risk of adhesions developing?

Pelvic
Gynaecological
Colorectal

How well did you know this?

Not at all

Perfectly

How can hernias cause damage to small bowel?

They can cause strangulation of the bowel as it is forced through a small space it shouldn’t go

What are some risk factors for getting an incisional hernia?

Smoking
Obesity
Cutting across natural lines of muscle

What is intesussception?

The telescoping (invagination) of one bit of intestine into another

Which medical conditions is intesussception associated with?

Cystic fibrosis Henoch-Schonlein purpura (inflammation of small blood vessels)

What causes intesussception?

An imbalance of the longitudinal forces along the intestinal wall A disorganised pattern of peristalsis

What is the intussusceptum?

The invaginating portion of bowel in an intesussception

What is the intussuscipiens?

The receiving portion of bowel in an intesussception

While examining the abdomen of a patient with intestinal obstruction, you hear dull sounds? What does this mean?

There is fluid filling the bowel in the area you are examining

While examining the abdomen of a patient with intestinal obstruction, you hear tympanic sounds? What does this mean?

There is gas filling the bowel in the area you're examining

What sort of bowel sounds do you hear in intestinal obstruction?

Tinkling These disappear at late stages

What investigations should you do in a suspected SBO?

Blood tests: FBC, U+E, lactate (increased in some cases of obstruction) X-ray: look for build up of gas, faeces and ischaemia CT: use contrast to show up blockage Ultrasound + MRI

Which people is intesussception most commonly seen in?

Infants + toddlers

What would you find by palpation in a patient with intesussception?

Sausage shaped mass in right upper quadrant

Management of SBO?

Fluid resuscitation Insert NG tube to decompress bowel (removal of contents by suction) Analgesia + anti-emetic Consider surgery Antibiotics

When should you immediately operate in SBO?

Signs of strangulation | Perforation + peritonitis

What can you to surgically to treat SBO?

Remove the cause of obstruction Bypass the segment Resection Exteriorisation (stoma bag)

What are the causes of large bowel obstruction?

Malignancy Volvulus Strictures (narrowing) Congenital fault

Describe the progression of obstruction to peritonitis.

Obstruction Proximal dilatation Increased colonic pressure = decreased mesenteric blood flow Mucosal oedema caused by fluids + electrolytes in the lumen Arterial blood supply is compromised Mucosa becomes ischaemia Ulceration Necrosis Perforation Bacteria escape to peritoneum

What happens if the ileocaecal valve is incompetent?

It won't open and you'll get faeculent vomiting

Why would a volvulus occur?

Sometimes the bowel just twists on itself spontaneously!

What is a closed loop obstruction?

A 360 degree twist/volvulus

Why do loop obstructions perforate?

``` Increase in pressure in section Impaired blood flow Ischaemia Necrosis Perforation ```

In colorectal tumours, where does perforation occur?

At the site, rather than proximally Because perforation is caused by local invasion of the tumour and inflammation of area

Volvuli present suddenly. True or false?

True

What would you find on examination of someone with LBO?

Distension Resonance Palpable mass Digital rectal examination: - empty rectum - hard stools - blood

Investigation of LBO?

Bloods: FBC, U+E, lactate X-ray + CT Contrast enema Endoscopy: look at mucosa, risk of perforation, can be therapeutic

What is the significance of lactate in intestinal obstruction?

High levels indicate some types of bowel obstruction

What signs are seen on AXR in large bowel obstruction? Where would obstruction be and what would it be if you saw these signs?

Coffee bean Bird of prey Sigmoid volvulus

How would you manage a non-perforated LBO?

Drip and suck: IV fluids, NG tube Use a rigid or flexible sigmoidoscopy to straighten out

How would you manage a perforated LBO?

Emergency surgery Resect Wash out peritoneum + bowel

What is non-mechanical obstruction?

Failure of peristalsis Adynamic bowel No mechanical cause

What are the clinical features of non-mechanical obstruction?

Pain free Distention Vomiting not projectile Absent or tinkling bowel sounds

How do you treat non-mechanical obstruction?

``` Nil by mouth IV fluids Nasogastric aspiration Treat the underlying cause Supportive nutrition ```