Bowel Obstruction Flashcards
Define bowel obstruction.
Partial or complete blockage of the bowel that results in failure of the intestinal contents to pass
What are the three different groupings of classification of bowel obstruction?
Small bowel vs large bowel
Complete vs partial (complete no gas or faeces)
Acute vs chronic
What classification of bowel obsruction is always an acute situation?
Complete obstruction
What are the three main causes of bowel obstruction?
Adhesions
Hernias
Malignancy.
What are all potential causes of bowel obstruction?
Three main: adhesions, hernias, malignancy
Other causes:
Volvulus
Stricture - 2 to Crohns or diverticular disease
What background questions are important to ask a patient to help determine the cause of a bowel obstruction?
Hernias
Change in bowel habit, weight loss, PR bleeding
Previous abdominal surgery may have resulted in adhesions.
What are the three different classifications of bowel obstructions based on the location relative to the bowel wall?
Intraluminal - in the lumen - ingestion of a foreign body
Intramural - in the wall - cancers,
Extramural - outside the wall - hernias, cancer, adhesions
What is the difference between a dynamic (mechanical) and adynamic bowel obstruction?
Dynamic - physical blockage aka foreign body
Adynamic - failure of peristalsis, muscular or neurogenic.
What is the difference between a simple and a strangulated bowel obstruction?
Simple - blood flow is not compromised manage conservativly
Strangulated - blood flow is compromised is a surgical emergency
What are some common causes of obstructed bowel by age group?
Neonates - atresia, meconium, hirschsprung,
Infants - introsusception, pyloric stenosis, meckles diverticulum,
YA - adhesions, strangulated hernia
Adult - hernia, adhesion, inflammation, carcinoma
Elderly - CA, inflammation, sigmoid volvulus, impacted faeces.
What is a volvulus?
When the intestines twist around itself and its supplying mesentery - results in cut of blood supply to this section of bowel.
What is intussusception?
When the bowel folds into the section next to it, telescopes - cause of bowel obstruction.
What are the key signs and symptoms of a bowel obstruction?
Nausea and vomiting (green bilious vomiting)
Absolute constipation (no stool or wind)
Abdominal pain - generalised
Abdominal distention
‘Tinkling’ bowel sounds
Dehydrated - colon responsible for reabsorbing fluid/water
What are the cardinal symptoms of bowel obstruction?
Colicky abdominal pain
Vomiting
Distention
Obstipation/constipation
How do the symptoms differ between a high/low small bowel obstruction and a large bowel obstruction?
High - early vomiting
Low SI - distention and vomiting
Large - constipation, vomiting is later to develop
What investigation are important for suspected bowel obstruction?
Bloods - lactate (bowel ischemia), U&Es (electrolyte imbalances e.g hypokalemia), venous blood gas (metabolic alkalosis from vomiting)
Bedside - PR exam for impacted foecal matter, VBG for metabolic acidosis (ischemia, severe hypovolemia anaerobic metabolism) or metabolic alkalosis (excess vomiting - loss of hydrogen)
Imaging - CT abdomen (confirm location, perforation is present) , AXR (confirm presence of), Erect CXR (look for perforation)
What is a radiological sign of perforated bowel obstruction?
Pneumoperitoneum - air under the diaphragm
What is the initial non surgical management in all patients with a bowel obstruction?
NBM
“Suck and Drip” - NG tube - Ryle’s tube - to decompress the stomach/bowel, IV fluids rehydrate and address electrolyte abnormalities
Analgesia.
What are the surgical management options for a bowel obstruction?
- Do-nothing - uncomplicated obstruction, stable patient, secondary to adhesion
- Adhesiolysis - laparoscopic surgery to cut adhesion
- Hernia repair
- Colonic stenting - 2 to cancer, performed via colonoscopy
- Bowel resection
What is the difference between a low and high anterior resection of the bowel?
High - upper rectum (1/3) and sigmoid/lower left colon
Low - lower rectum and sigmoid colon
what is the surgical procedure where the sigmoid colon is removed called?
Sigmoid colectomy
What are the different types of hemicolectomy?
Left hemi - distal transverse and descending
Right hemi - - caecum, ascending and up to mid transverse
Extended right hemi -same as above but up to transverse colon at the splenic flexure
What is a total abdominal colectomy?
Remove entire large colon
What is a subtotal colectomy?
Removes all of large intestins except the sigmoid colon
What is a total proctocolectomy?
Surgical removal of the colon and the rectum
What is an abdominal-perineal resection?
Surgical procedures to remove the anus, rectum and sigmoid colon.
What is a Hartmans procedure?
Type of colectomy - removes part of the sigmoid colon, remaining rectum is sealied, creating Hartmans pouch, remains colon is redirect to a colostomy
Majority of large bowel obstructions occur in the sigmoid colon.
In the case of bowel obstruction what are the indications for emergency surgery?
Clinically unstable patients with a life-threatening condition.
Includes evidence of confirmed or pending - perforation, ischaemia, necrosis.
What is the most common cause of small bowel obstruction?
Adhesions (90%) - most likley in patients with a history of previous abdominal surgery.
Hernias also common
How does the management plan for bowel obstruction tend to change based on the cause of the obstruction?
If adhesive SBO’s -try conservative - most resolve on own, surgery would inc risk of further adhesions
Non-adhesive - tend to require surgery.
What is more common small or large bowel obstruction?
Small bowel
What are the features of a small bowel obstruction on an x-ray?
Central positions of gas-filled and distended loops of bowel
Valvulae conniventes - white lines passing full width of bowel - muscoal foldings.
What are the main causes of large bowel (colorectal) obstruction?
Colon cancer - 60% - is the presenting complaint in 30% of colon cancer diagnosis
Volvulus
Severely impacted constipation.
What is the surgical management required for large bowel (colorectal) obstruction?
75% of cases require surgical intervention
Colorectal resections are common.
What are the features shown on the x-ray?
What diagnosis do they suggest?
Suggest a large bowel obstruction
Dilated transverse and sigmoid colon
Abrupt cut-off at point of obstruction
Haustra - pouches formed by mucosa, do not extend full width of the bowel.
What are some potential complications of a bowel obstruction and its management?
Surgical treatment - increase risk of adhesion and repeat obstruction, short bowel syndrome
Perforated bowel - peritonitis
Aspiration - pneumonia
Strangulated bowel and ischemia/necrosis - sepsis
What is meant by a closed loop obstruction?
When the section of the bowel is obstructed at both sides, so content can not drain proximally or distally
Can be caused be two adhesion, hernias (with a loop of bowel out), large bowel obstruction + a competent ileocaecal valve.
Is an emergency, more likely to continue to expand leading to ischemia and necrosis.
What is the epidemiology of bowel obstruction?
80% small bowel obstructions
SI obstruction - Found in around 10% of over 65yrs presenting to A&E with abdominal pain
6% mortality rate, increasing to over 10% when surgery is required.
What are some common causes of gastrointestinal perforation?
Appendicitis
Crohns disease
Peptic ulcers
Bowel obstruction
Diverticulitis
