Bowel obstruction Flashcards
What are the classical signs of an obstructed bowel?
Abdominal pain Vomiting= green bilious Nausea Diffuse abdominal pain Absolute constipation + lack of flatulence Abdominal distention Tinkling bowel sounds (due to increased peristalsis to try and counter the obstruction) Faecular vomit or breath Dehydration due to vomiting Tympanic abdomen
What signs/symptoms can you use to differentiate between a small or large bowel obstruction? What imaging is important for differentiating between locations?
Small: Vomiting presents early + bile stained Less distended abdomen Pain located higher in abdomen Colicky abdo pain
Large
Vomit thicker and faeculent
Pain more constant
More gradual onset of symptoms
What is ileus? When does it commonly occur and how can it be managed?
Functional obstruction due to decreased or absent bowel activity which can be mistaken for mechanical obstruction
V common post-operative due to handling of bowel
When potassium and magnesium levels drop which prevent normal contraction
Can also occur as a consequence of proximal dilation of bowel in bowel obstruction which disruptions peristalsis
NG tube to aspirate
What are the 3 different types of abdominal obstruction and how can you differentiate between them?
Simple= one obstruction point and no vasculature compromised
Close loop (sigmoid volvulus)= obstruction at two points which leads to formation of distended loop at risk of perforating
Strangulated:
-blood supply compromised
-patient appears more unwell than you would expect
-pain is sharper, more localised and more constant
-signs of mesenteric ischaemia i.e. fever. + raised WCC
What are the causes of small bowel obstruction?
Adhesions due to previous surgery/infection/inflammation
Hernias (strangulated)
Malignancy
What are the causes of large bowel obstruction?
Colon cancer Paralytic ileus = no peristalsis Sigmoid volvulus Constipation/faecal impaction Diverticular stricture Caecal volvulus
What is the immediate treatment for bowel obstruction?
Drip and suck:
- NGT in to provide rest for bowel and enable stomach contents to drain freely to limit the risk of being sick i.e. decreasing the pressure in stomach
- IV fluids to rehydrate and restore electrolyte balance
- NBM
- analgesia
- VTE prophylaxis
Who is most at risk of developing a sigmoid volvulus? Why does it occur? How does it characteristically present on a AXR?
Elderly, co-morbid, constipated patients
Sigmoid mesentery becomes weakened which eventually leads to the bowel twisting on the mesentery about 180 degrees to form loop strangulated obstruction
Coffee bean shaped
Why can hypovolaemia and shock occur with bowel obstruction?
Fluid is secreted by small bowel which is normal reabsorbed in the colon HOWEVER obstruction means that fluid is unable to reach colon to be reabsorbed leading to fluid loss without reabsorption
Called “THIRD-SPACING”
What are the main causes of intestinal adhesions?
Abdominal or pelvic surgery
Peritonitis
Abdominal/pelvic infections (pelvic inflammatory disease)
Endometriosis
What is a closed-loop obstruction and when does it occur?
2 points of obstruction along the bowel
Adhesions compressing 2 areas
Hernias which lead to isolation of bowel
Volvulus= section of bowel twists
Single point large bowel obstruction with competent ileocaecal valve
What are the complications associated with closed-loop bowel obstruction?
Closed ends mean not way for contents to drain leading to expansion of section of bowel
==increased risk of perforation and ischaemia
What investigations would you do in suspected BO?
What type of imaging can be done to identify bowel obstruction? What would you find and what would indicate a red flag complication?
FBC/LFTs/U+E/Amylase
AXR + CXR (erect)
Distended loops of bowel
Valvulae conniventes= mucosal folds forming lines extending full width of bowel
Haustra= lines which do not extend the full way across the large bowel
Pneumoperitoneum= air under the diaphragm due to perforation of bowel
CT AP- if needed more info
DRE
-feel for faecal impaction
How would you differentiate distended small bowel from distended large bowel on X-ray?
SB -central -will have lines that cross the entire width of the bowel I.e. valvulae conniventes -diameter >3cm -no gas in colon
LB
-peripheral
-lines which do not cross the entire width of the bowel wall
I.e. haustra
-diameter >6cm
-distended caecum >9 cm
-no gas on rectum (unless AXR done post DRE which can push air into rectum)
What is the initial management of someone who is suspected to have a bowel obstruction?
ABCDE approach
Assess if patient haemodynamically stable
U+Es= electrolyte balance
VBG= metabolic acidosis due to vomiting stomach acid
Raised lactate= due to bowel ischaemia
