General surgery (2) (Common conditions) Flashcards
intestinal obstruction summary
Passage of food, fluids and gas become blocked.
- Small bowel more common than large bowel
- Results in build up of gas and faecal matter proximal to obstruction
- Back pressure- vomiting and dilatation of proximal intestines
- Surgical emergency
how can intestinal obstruction cause dehydration
- Obstruction also reduces fluid reabsorption in the colon- fluid loss from intravascular space – hypovolaemia
- This is called third-spacing
- Higher up the obstruction the worse the fluid losses- less bowel where the fluid can be reabsorbed
3 main causes of intestinal obstruction
The big three (HAM)
• Hernias (small bowel)
• Adhesions (small bowel)
• Malignancy (large bowel)
causes of small bowel obstruction
- Hernias
- Adhesions
- Scar tissue that binds abdominal contents together
- Causing kinking or squeezing of the bowel
- Causes
- Surgery
- Peritonitis
- Infection
- Endometriosis
- Stricture
causes of large bowel obstruction
- Malignancy
- Volvulus- bowel twists on self
- Diverticular disease
causes of small and large bowel obsturction
- Stricture e.g. secondary to Crohns
- Intussusception (in young children 6m-2y)
RF for obstruction
- Abdominal surgery
- Cancer
- Hernias
- Crohns disease
presentation of obstruction
- Vomiting (particularly green bilious vomiting)
- Early- upper
- Later- lower
- Abdominal distention
- Diffuse abdominal pain
- Absolute constipation and lack of flatulence (early in lower,
Late in upper)
- “Tinkling” bowel sounds may be heard in early
bowel obstruction
investigations of obstruction
-
Abdominal X-ray – distended loops of bowel
- Upper limits of normal diameter of bowel
- 3cm small. Bowel
- 6cm colon
- 9cm caecum
- Upper limits of normal diameter of bowel
- May skip straight to contrast abdominal CT- confirm diagnosis and establish site and if perforation has occurred- modality of choice
- Blood tests: U and E (electrolytes), venous blood gas (metabolic alkalosis due to loss of HCL in vomit), vowel ischaemia- raised lactate)
small bowel AXR
- Dilated >3cm
- Central, valvulae conniventes
- String of pearls sign
- Paucity of gas in large bowel (i.e. not in the rectum)
large bowel obstruction AXR
- Colon >6cm, caecum >9cm
- Peripheral and haustra (don’t extend full width)
initial management of obstruction
- ABCDE
- Hypovolaemia shock due to third spacing
- Bowel ischaemia
- Bowel perforation
- Sepsis
- Nill by mouth
- Analgesia, catheterise
- IV fluids to hydrate and correct electrolyte imbalances
- NG tube with free drainage to allow stomach contents to freely drain and reduce risk of vomiting and aspiration
- Conservative treatment if adhesions or volvulus, where this fails- surgery
surgical intervention for obsturction
intervention (closed loop or ischaemia- pain)
- Definitive management – either laparoscopy or laparotomy
- Exploratory surgery in patients with an unclear underlying cause
- Adhesiolysis to treat adhesions
- Hernia repair
-
Emergency resection of the obstructing tumour- may need stoma
- Stents may be inserted- holds tumour out of the way
volvulus on x-ray
- Sigmoid volvulus- coffee bean appearance
- Caecal volvulus- fetal appearance
Closed loop obstruction
Where there are two points of obstruction along the bowel; meaning that there is a middle section sandwiched between two points of obstruction.
Result: contents of section of bowel does not have open end to drain- bowel continues to expand- ischaemia and perforation
This might happen with:
- Adhesions that compress two areas of bowel
- Hernias that isolate a section of bowel blocking either end
- Volvulus where the twist isolates a section of intestine
- A single point of obstruction in the large bowel, with an ileocaecal valve that is competent
what is the significance of a competent ileocaecal valve
- A competent ileocaecal valve does not allow any movement back into the ileum from the caecum. When there is a large bowel obstruction and a competent ileocaecal valve, a section of bowel becomes isolated and the contents cannot flow in either direction.
The complications of bowel obstruction include:
*
- Bowel ischaemia
- Bowel perforation leading to faecal peritonitis (high mortality)
- Dehydration and renal impairment
hernias (summary)
Occur when there is a weak point in a cavity wall, affecting muscle or fascial- this weakness allows body organ e.g. bowel that would. Normally be contained within that cavity to be passed through the cavity wall
types of hernia
- Inguinal
- Femoral
- Umbilical
- Incisional
- Hiatus hernia
Specific abdominal hernias
-
Richter’s hernia
- Specific situation
- Only part of bowel wall and lumen herniate through defect, other side of that section of bowel remains within peritoneal cavity
- Risk of strangulation
- Surgical emergency
-
Maydls hernia
- Two diff loops of bowel are contained within hernia
assessing a hernia
- does it go back in by itself or is it reducible
- get patient to cough and feel over
- get patient to lie down
- pain?
When assessing a hernia, always comment on the size of the neck/defect (narrow or wide), as this will help formulate a risk assessment (risk of strangulation reduced if wider neck) and management plan for the hernia (such as how urgently they need to be operated on).
causes of hernias
anything which increases pressure in abdomen
- Lifting heavy objects
- Diarrhoea or constipation
- Persistent coughing
risk factors of henrias
- Pregnancy
- Weight-lifting
- Constipation
- Obesity
basic anatomy of bile duct
- The right hepatic duct and left hepatic duct leave the liver and join together to become the common hepatic duct.
- The cystic duct from the gallbladder joins the common hepatic duct halfway along.
- The pancreatic duct from the pancreas joins with the common bile duct further along.
- When the common bile duct and the pancreatic duct join they become the ampulla of Vater, which then opens into the duodenum.
- The sphincter of Oddi is a ring of muscle surrounding the ampulla of Vater that controls the flow of bile and pancreatic secretions into the duodenum.
MRCP
Magnetic resonance cholangio-pancreatography (MRCP)
- MRI scan- detailed image of biliary system
