small intestine Flashcards
What are the top causes of small bowel obstruction
hernias and adhesions
If neoplastic disease causes small bowel obstruction, what is more likely to be
-Metastatic peritoneal disease (rather than small bowel primary tumour)
What is usually the cause of intussusception in adults
usually there is a pathological lead point ie tumour
Causes of small bowel obstruction
Extrinsic -adhesions -Hernia: external, internal -neoplastic: primary, metastatic -intraabdominal sepsis/ abscess (Ruptured appendix/ diverticulum) Wall -congenital: malrotation, cystic fibrosis , meckels diverticulum -Inflammatory: Crohns disease -Infectious: TB, actinomycosis -Traumatic: haematoma, ischaemic stricture -Neoplastic -Other: intussusception, endometriosis, radiation stricture Lumen -Gallstone -Bezoar -Foreign body -Enterolith
Causes of strictures of the bowel
Inflammatory conditions such as Crohns, radiation injury and infectious causes
How may gallstones cause an obstruction in the small bowel
Enter the small intestine through a cholecystenteric fistula and usually lodge in the terminal ileum, unable to pass the ileocecal valve
Symptoms of small bowel obstruction
- Abdominal discomfort/ colicky pain
- Abdominal distension
- Nausea and bile stained vomiting
- Obstipation
How does the symptom of nausea and vomiting vary based on the site of obstruction
nausea and vomiting are more likely in patients with more proximal obstruction. Patients presenting with distal SBO and presenting later in the course of obstruction may have faeculent vomiting
Signs to look for on examiantion in small bowel obstruction
- Gaseous distention
- Previous surgical scars
- Early vigourous peristalsis
- Masses (peritoneal, tuberculous)
- Signs of malignancy: HSM, periumbilical mass, Virchow node
- Localised Rebound tenderness and guarding sugget perforation
- Examine hernia sites
- Blood on rectal exam (Intussusception/ infarction) or masses
Abdominal xray features of small bowel obstruction
- Dilated loops of small bowel (>3 cm in diamter) and absence of dilated large bowel
- Multiple air fluid levels in a step pattern
- Xray may detect foreign bodies, a gallstone in the small intestine or air in the billiary tree (suggesting cholecystenteric fistula
- Free air in abdominal Xray indicates perforation and necessitates urgent surgery
What information does Ct give in small bowel obstruction
- Diagnosing carcinoma
- Other extrinsic lesions (eg intraabdominal abscess)
- more accurately determining the level of the obstruction
- Detect irreversible necrotic bowel
What does raised lactate and acidosis indicate
Indicators of bowel necrosis
General treatment of small bowel obstruction
- Aggressive early fluid resuscitation with appropriate replacement of electrolytes
- patients kept nil per mouth with nasogastric tube and urinary catheter
- Non mechanical bowel obstruction must be excluded
How is adhesive bowel obstruction managed
Managed Conservatively by IV line and nasogastric tube as long as there is no suspected perforation. If patient shows no sign of improvement or deteriorates then surgery for adhesiolysis may be required (via laparotomy or laporoscopy). At surgery, adhesions are released, non-viable bowel resected and anastomoses or stomas made as required.
Causes of spontaneous small bowel perforation
-TB
-Typhoid
-CMV
-Malignancy
-Crohns disease
Steroids
-Radiotherapy
How may immunocompromised patients present with small bowel perforation
They may present with few clinical signs other than general malaise
How do patients with short bowel syndrome present
they present with incapacitating diarrhea, steatorrhea and malnutrition
When is short bowel syndrome inevitable
patients with 100 cm or less of small intestine remaining
Management of short bowel syndrome
- Most will require lifelong parenteral nutrition
- Small bowel transplant alternative for some
Other than duodenal ulcers, what are causes of small intestine haemorrhage
- vascular abnormalities of the mucosal wall
- Small bowel Crohns disease
- ileal diverticulum of meckel
Where is a meckels diverticulum usually situated
40 cm from the ileocaecal junction. It may be free or attached by a cord to the umbilicus
How may meckels diverticulum present
- More commonly presents with bleeding
- May clinically mimic appendicitis or present with obstruction
Benign tumors of the small bowel
Gastrointestinal stromal tumours, adenomas, lipomas
Malignant tumours of the small bowel
Adenocarcinomas, carcinoids, lymphoma
