GI obstruction Flashcards
What are the three broad anatomical types of GI obstruction?
- Gastric outlet obstruction
- Small bowel obstruction
- Large bowel obstruction
Name three causes of gastric outlet obstruction
- Peptic ulcer disease
- Gastric cancer; gastric polyps
- Ingestion of caustic substances
- Pyloric stenosis
- Pancreatic malignancy; pancreatic pseudocysts
- Duodenal cancer; ampullary cancer
- Cholangiocarcinoma; Bouveret syndrome
What are the cardinal symptoms of gastric outlet obstruction?
- Nausea
- Vomiting
- Post-prandial
- Non-bilious; undigested food
- Epigastric pain
What is Bouveret syndrome?
Subgroup of gallstone ileus
Cholecystoduodenal fistula allows the passage of a stone which impacts in the duodenum and causes gastric outlet obstruction
Outline the management of gastric outlet obstruction
-
‘Drip and suck’
- Maintain hydration and electrolyte balance (esp Cl-)
- Gastric decompression using NG tube
- Treat underlying causes where possible:
- If PUD ➔ IV omeprazole or Lansoprazole
- Gastric polyps ➔ endoscopic excision
- Pyloric stenosis ➔ Pyloromyotomy
- Malignant causes ➔ metallic stenting
What electrolyte imbalance is associated with gastric outlet obstruction?
Metabolic alkalosis due to vomiting
What are the cardinal features of intestinal obstruction?
- Colicky pain
- Vomiting: bilious or faeculent
- Distension
- Absolute constipation
What is ‘faeculent’ vomiting?
Vomiting of faeces due to bacterial fermentation of intestinal content in established obstruction
What are the two types of obstruction?
- Ileus (functional): reduced bowel motility
- Mechanical obstruction
What radiographic features are seen in Gallstone ileus?
Rigler’s triad:
- Opacity in RIF
- Dilated small bowel
- Air in biliary tree
Name four presenting features of small bowel obstruction
- Abdominal pain: paroxysmal colicky
- Faeculent vomiting
- Obstipation; failure to pass flatus
- Abdominal distension
- Visible peristalsis; hernia; scar
- High-pitched tinkling bowel sounds
- Dehydration; peritonitis
Name three causes of small bowel obstruction
- Adhesions
- 60-70% of adhesional SBO is self-limiting
- Hernias
- Tumours: eg. GI stromal tumour; carcinoid tumour; lymphoma
Name two causes of adhesions
- Surgery
- Extensive surgery may cause more adhesions
- May appear many years after a surgical procedure
- Trauma
- Intra-abdominal infection: eg. salpingitis, appendicitis
Which hernias commonly cause obstruction?
- Femoral hernia: narrow femoral canal
- Inguinal hernia: high prevalence
- Some parastomal or incisional hernias
On x-ray, when is the small bowel considered obstructed?
Small bowel dilation >3cm
On x-ray, when is the large bowel obstructed?
Large bowel dilation >6cm
On x-ray, when is the caecum obstructed?
Caecum dilation >9cm
Differentiate the presentation of large bowel obstruction vs small bowel obstruction
Similar signs and symptoms
- Large bowel:
- Vomiting occurs later
- Intervals between paroxysms of pain are longer
- PR exam may show mass
- Small bowel:
- Vomiting occurs earlier
- Distension is less
- Pain higher in abdomen.
Differentiate the small bowel and the large bowel on x-ray
- Small bowel:
- Central
- Valvular conniventes
- Gas or fluid
- Large bowel:
- Peripheral
- Haustral folds
- Gas or faeces
Name three complications of small bowel obstruction
- Intestinal perforation
- Intestinal necrosis
- Sepsis; multi organ failure
- Intra-abdominal abscess
- Short bowel syndrome
What is short bowel syndrome?
Malabsorption disorder due to either the physical or functional loss of small bowel
What are the indications for surgery in adhesional small bowel obstruction?
Majority of adhesional SBO is self-resolving
Indications for surgery include:
- Fever
- Peritonitis
- Perforation on imaging
- Failure of resolution
Which bowel obstructions require emergency surgery?
Strangulation or Closed loop obstruction
Both carry risk of perforation and peritonitis
Outline the initial management of mechanical bowel obstruction
- ‘Drip and suck’
- Maintain hydration and electrolyte balance (esp Cl-)
- Gastric decompression using NG tube
- Treat underlying causes where possible
Name three causes of large bowel obstruction
- Colorectal carcinoma
- Diverticular disease
- Volvulus
Where are the commonest locations for volvulus?
- Sigmoid: due to its mesentery
- Caecum: non-fixed
How is sigmoid volvulus obstruction treated?
Flatus tube or flex-sigmoidoscopy to decompress the obstruction
How does an ileus differ from mechanical obstruction on examination?
- Ileus:
- No pain
- Absent bowel sounds
- Mechanical obstruction:
- Pain
- Higher-pitched tinkling bowel sounds
Which two causes of obstruction are not managed operatively?
- SBO: Adhesions without peritonitis
- LBO: Sigmoid volvulus without peritonitis
