Intestinal obstruction and perforation Flashcards
How can intestinal obstruction be broadly classified?
Compare these
Mechanical: physical obstruction (increased peristalsis)
Non-mechanical: reduced or absent peristaltic
List 4 causes of mechanical intestinal obstruction
- Adhesions (small bowel)
- Hernias (small bowel)
- Malignancy (large bowel)
- Volvulus (large bowel)]
+ diverticular disease, strictures (2o Crohn’s), Intussusception
List 3 causes of Non-mechanical intestinal obstruction
- Paralytic ileus
- Colonic Pseudo-obstruction (Ogilvie’s syndrome)
- Neuromuscular
Pathophysiology of obstruction?
How does intestinal obstruction present?
- Green bilious vomiting
- Diffuse abdominal pain and distention
- Absolute constipation and lack of flatulence
- Abnormal bowel sounds
What is bilious vomiting?
Containing bright green bile
Describe the bowel sounds heard in mechanical obstruction
Can be high pitched and “tinkling” early in the obstruction and absent later
Initial imaging for suspected bowel obstruction
What will this show?
Abdominal X-ray showing distended loops of bowel
What are the normal diameters of the small bowel, colon and caecum?
- 3 cm small bowel
- 6 cm colon
- 9 cm caecum
How do we differentiate between a small vs large bowel obstruction on X-ray
Small bowel obstruction:
- Dilated bowel (>3cm)
- Central abdominal location
- Valvulae conniventes (lines completely cross width of the bowel)
Large bowel obstruction:
- Dilated bowel (> 6cm, or > 9 cm at caecum)
- Peripheral location
- Haustral lines (lines do not completely cross bowel width)
Gold standard imaging to confirm bowel obstruction?
A contrast abdominal CT scan
To confirm diagnosis and establish the site and cause
Initial management of intestinal obstruction?
ABCDE approach and “drip and suck”
- Nil by mouth
- IV fluids
- NG tube with free drainage
What blood findings must we look out for in bowel obstruction?
What do these indicate
- Electrolyte imbalances (U&Es)
- Metabolic alkalosis due to vomiting stomach acid (VBG)
- Bowel ischaemia (↑lactate)
What is the definitive management of bowel obstructions?
Surgery (either laparoscopy or laparotomy) to correct the underlying cause
List 4 complications of bowel obstruction?
- Hypovolaemic shock
- Bowel ischaemia
- Bowel perforation
- Sepsis
How does bowel obstruction lead to shock?
Due to fluid stuck in the bowel rather than the intravascular space (third-spacing)
Leads to Hypovolaemic shock
List 4 causes of Closed-Loop Obstruction
- Adhesions that compress two areas of bowel
- Hernias
- Volvulus
- Single point of obstruction in the large bowel, with a competent ileocaecal valve
What is meant by a Closed-Loop Obstruction?
Where there are two points of obstruction along the bowel; meaning the middle section is sandwiched between
What is the risk of an untreated close-loop obstruction?
Will inevitably expand, leading to ischaemia and perforation
Requires emergency surgery
What are Bowel adhesions?
Scar tissue that bind the abdo contents together → causes kinking/squeezing of the bowel, leading to obstruction
Are adhesions more common in the small or large bowel?
small
List 4 causes of bowel adhesions
- Abdominal or pelvic surgery
- Peritonitis
- Abdominal or pelvic infections (eg. PID)
- Endometriosis
What is a volvulus?
Torsion of the colon around it’s mesenteric axis resulting in compromised blood flow and closed loop obstruction
Affected bowel can become ischaemic rapidly leading to bowel necrosis and perforation
List 4 risk factors for a volvulus
- Parkinson’s
- Elderly
- Chronic constipation
- High fibre diet
- Pregnancy
- Adhesions
List 2 locations where a volvulus tend to occur
Highlight the most common
- Sigmoid colon
- Caecum
Initial investigation for a suspected volvulus?
Classic finding?
Coffee bean sign - indicative of sigmoid volvulus
Investigation of choice to confirm diagnosis of sigmoid volvulus?
Contrast CT
Initial management of a sigmoid volvulus?
‘Nil by mouth’ and ‘Drip and suck’
Conservative management of a sigmoid volvulus?
endoscopic decompression (only if there is NO peritonitis)
Surgical management of a volvulus?
- Laparotomy
- Hartmann’s procedure (sigmoid volvulus)
- Ileocaecal resection or right hemicolectomy (caecal volvulus)
What is paralytic ileus?
Condition affecting the small bowel, where normal peristalsis temporarily stops
List 4 common causes of Ileus
- Injury to the bowel
- Handling of the bowel during surgery
- Inflammation or infection
- Electrolyte imbalance (e.g., hypokalaemia or hyponatraemia)
How may the presentation of Ileus (non-mechanical) differ from mechanical obstruction?
Presentation is the SAME except there are absent bowel sounds (as opposed to the “tinkling” bowel sounds)
Management of Ileus
- Nil by mouth
- NG tube if vomiting
- IV fluids
- Mobilisation - helps stimulate peristalsis
- Total parenteral nutrition
Compare structures involved in an upper vs lower GI perforation
UGI perforations
UGI: eosophagus - small bowel (jejunum, ileum)
LGI: caecum - rectum)
How does GI perforation typically present?
- Sharp, rapid onset abdominal pain
- Systemically unwell
- Pain worse with breathing and moving
- Malaise, vomiting, and lethargy
What is the importance of diagnosis in GI perforation
Delay in resuscitation and management → septic shock, multi organ dysfunction, and death
Immediate ddx in anyone presenting with acute abdominal pain
List 4 causes of Upper GI perforation
- PUD
- Small bowel tumours
- Endoscopy
- Foreign body
How does a perforation in the thoracic region present?
- Pain in chest, neck or radiating to the back
- Worse on inspiration
- Vomiting
- Respiratory symptoms.
List 4 causes of Lower GI perforation
- Crohn’s disease
- Colon cancer
- Colonoscopy
- Diverticular disease
What classification system is used to assess severity of acute diverticulitis?
Hinchey
- I para-colonic abscess
- II pelvic abscess
- III purulent peritonitis
- IV faecal peritonitis
What may be seen on chest X-ray of bowel perforation?
Air under the diaphragm in pneumoperitoneum
What 2 signs may be seen on an abdominal X-ray of bowel perforation?
- Rigler’s sign (both sides of bowel visible *image) or
- Psoas sign (loss of sharp delineation of the psoas muscle border)
Gold standard imaging to confirm bowel perforation?
A contrast abdominal CT scan
To confirm diagnosis and establish the site and cause
Management of GI perforation?
- ABCDE
- Broad spectrum antibiotics
- Nil by mouth, NG tube, IV fluid resuscitation
- Analgesia
- Surgery
