small bowel obstruction Flashcards
Causes of small bowel obstruction? (4)
Adhesions (most common) 50%
Hernias 15%
Cancer 10%
Crohn’s
How to treat patients with Small bowel obstruction due to adhesions? (4)
- ABCDE
- Fluids + Electrolytes (Nasogastric tube)
- Gastrografin + X-Ray to assesses if surgery is needed
- Surgery (if needed)
How to treat small bowel obstruction due to hernia? (4)
Groin/femoral/umbilical - operate (almost always groin- ie. femoral)
High risk patient- Taxis (local anaesthesia and push back in)
High BMI- conservative measures
Incisional hernia (weakness at the site of previous surgery) - treat as adhesive SBO
Investigations to diagnose small bowel obstruction? (5)
Full blood count
Urea and electrolytes
Lactate
C-reactive protein
CT SCAN = 🔑 NOT X RAY
Most common complication of small bowel obstruction?
Renal failure
Percentage of intestinal obstruction that is small bowel?
60-75% of all cases
Presenting history of small bowel obstruction? (4)
-Pain in umbilical region that comes in waves = colic
-Bilious vomiting (dark green)
- bloating/ distension
- when did they last eat and drink?
Symptoms of small bowel obstruction? (3)
- Vomiting then constipations
- Mild abdominal distension + pain
- Tinkeling bowel sounds (*hyperresonant bowels on percussion in both types of intestinal obstruction)
Types of operation given for small bowel obstruction? (2)
-Key hole or open
-divide scar tissue
-risk of future scar formation
-minimally invasive surgery can help
What is small bowel obstruction?
- a mechanical disruption in the small bowel, leading to significant clinical symptoms such as bilious or faeculent vomiting, abdominal pain and distension, and complete constipation.
What to assess in a patient with potential small bowel obstruction? (9)
- hydration status
- weight loss
- pulse/bp
- O2 stats
- scars
- abdominal distension
- abdominal tenderness
- Hernia orifices
- PR exam
When would you advise surgery in adhesive SBO?
Signs of ischemia on a CT scan
Why use a CT scan for suspected small bowel obstruction?
- identifies site
- Indicates cause
Tells you if bowel is ischaemic from:
- poor enhancement
- free fluid
- twisted mesentery
epidemiology
- common
- adhesions following abdominal surgery - 60-70% of cases
- incidence increases with age due to increasing rates of surgery, malignancies and predisposing conditions
aetiology DELETE
factors outside the bowel:
- adhensions
- intra-abdominal hernia
factors relating to bowel wall:
- crohns disease
- appendicitis
factors relating to inside the bowel:
- malignancy
- foreign body ingestion
- gallstone ileus
Diseases causing small bowel obstruction in children
Intussusception
Volvulus
Intestinal atresia
Appendicitis
aetiology - adhesions
- Most common cause in the Western world
- Prior intra-abdominal surgeries increase the risk of adhesion development. The larger the operation, the higher the likelihood of adhesion formation.
crohns - aetiology
stricturing (rather than fistulating) disease is what specifically causes SBO
- stricturing - narrowing of lumen
- fistulating - development of abnormal passages
signs and symtpoms
- abdominal pain w distension - initial colicky that becomes continuous
- bloating and vomitting (often bilious)
- failure to pass flatus or stool
- history of abdominal/gyne durgery or hernia
- tympanic, high pitched bowel sounds on examination
- empty rectum on examination in complete bowel obstruction
other signs and symptoms
- fever
- significant fluid depletion
- peritonitis - indicated severe disease - necessity for surgical intervention
- simple or partial SBO may still result in passing some flatus / stool + mild temperature
what can it lead to if left untreated
ischaemia or necrotic bowel
leading to perforation
investigations
FBC - WCC raised
U&E - look at renal function
- low lactate - bowel ischaemia / necrosis
- amylase - rule out acute abdomen conditions
abdominal xray:
- upright - to detect pneumoperitoneum
- absense of air in the rectum can indicate complete obstruction
- Distinguish between small bowel and large bowel via valvulae conniventes (small) vs haustra (large)
- As a general rule of thumb, dilatation of the small bowel > 3cm, the large bowel > 6cm or the caecum > 9 cm, is suggestive of abnormal dilatation.
Gold standard:
Contrast Abdominal CT scan - shows where obstruction is, the cause, and if the bowel is ischaemic (ischemia indicates obstruction and the need for surgery)
Valvulae conniventes
folds in the small intestine that are also known as Kerckring folds, plicae circulares, or small bowel folds
normal
central or diffuse gas pattern
distribution of gas throughout the small bowel
luminal air fluid levels
multiple usually indicate intinestinal obstruction
stool in colon
minimal or absent
birds beak sign
absent
peritoneal fluid
may be seen due to irritation
Small bowel contrast study using gastrograffin
Used as a therapeutic measure in partial SBO
Presence of contrast in rectum 24 hours after ingestion signifies a resolving partial SBO, reducing the need for surgery
Diagnostic laparotomy/laparoscopy
- surgical procedures used to examine the abdomen
- Used to distinguish between partial and complete obstruction if imaging doesn’t provide clear evidence
- laparoscopy - less invasive
management
- DR ABCDE
- fluid and electrolyte - reduce surgery risks
- fluid rescusitation and NG tube to aspirate content for decompression
- gastrografin in partial obstruction
if all fails consider surgery
pathology
- Obstruction leads to the build-up of gas and faecal matter proximal to the obstruction
- This causes back-pressure
- resulting in vomiting and dilatation of the intestines proximal to the obstruction
- Third Spacing - fluid secretions into the GI tract that are later absorbed into the colon
- These secretions can’t reach the colon due to small bowel obstruction
- Results in fluid loss from the intravascular space into the GI tract
= Leads to hypovolaemia and shock - worse more proximal blockage
pathology - adhesions
Definition - pieces of scar tissue that bind the abdominal contents together
Pathophysiology - cause kinking or squeezing of the bowel, leading to obstruction
Location - typically small bowel
closed loop obstruction definition and causes
Definition - two points of obstruction along the bowel - leading to a middle section sandwiched between two points of obstruction
Causes:
Adhesions
Hernias
Volvulus
Single point of obstruction with a competent ileocaecal valve - doesn’t allow flow back into the ileum from the caecum
closed loop pathology and treatment
Pathophysiology:
- No end from which fluids can drain and decompress, meaning it invariably keeps expanding
- bc of competent ileocecal valve not allowing contents to travel backwards
- Can lead to ischaemia and potentially perforation
Treatment:
- emergency surgery
presentation unique to small bowel
Early vomiting
Late constipation
*Watch the question as it might say vomiting for a week and constipation for 24 hours
gold standard
Contrast Abdominal CT scan - shows where obstruction is, the cause, and if the bowel is ischaemic (ischemia indicates obstruction and the need for surgery)
initial early management
analgesia
drip and suck
management - adhesions
open or keyhole surgery
management - hernias
- if inguinal/femoral or umbilical - operate
- consider alternative if high BMI
management - cancers
- Right-sided colon cancer = common
- Nutrition is a problem as cancer makes you malnourished
small brown macules on vermillion border of lips and palms of hands
peutz-jeghers syndrome
- common cause of SIO
how long after surgery is adhesive obstructions a risk
- fibrous tissue forming as part of healing process - adhesions start forming days after the surgery
- symptoms don’t appear until months or years later
post-operative ileus
- occurs due to reduction in bowel motility following a surgery
- form of functional bowel obstruction
- bowel sounds are absent
- can be managed conservitavely
- symptoms similar to normal
types of post-operative ileus
- mechanical
- paralytic
paralytic:
- neurogenic
- both similar presentations
- silent bowel sounds
- lack of cholicy pain
- obesity - risk factor
- anticholonergic + opiate - risk factor
- expected for 24-48hrs after surgery
- any longer required intervention
signs of partial vs complete bowel obstruction
complete:
- severe, continuous abdominal pain
- rigid abdomen with rebound tenderness
- complete absence of bowel sounds / high pitch
- severe abdominal distension
- frequent forceful vomitting
- severe dehydration and electrolyte balance
partial
- intermittent abdominal pain
- some passage of gas or stool
- less severe distension
- nausea and occassional vomitting
- hyperactive bowel sounds
what to do when full SBO is there
urgent surgery
another name for nasogastric tube
ryles tube
paralytic vs mechanical ileus CT
- paralytic - dilated loops of small and large bowels
- mechanical - diffuse bowel dilation without distinct transition point
riglers sign
- double wall sign
- crisp definition of both sides of the bowel wall
- means theres air on both sides of bowel wall
- if no recent surgery - means perforation
paralytic vs mechanical ileus
paralytic - intestines lose their ability to contract - functional blockage
mechanical - physical obstruction causing blockage - specific type of sbo where it is a physical blockage/barrier
findings on a ct suggestive of sbo
- dilated loops >2.5cm in diameter
- transition zone
dilated loops
when small bowel loops >2.5cm
transition zone ct
area where diameter of small bowel abruptly changes from dilated to collapsed
