Pathophysiology of hernias + principles of hernia repair Flashcards
1
Q
What is a hernia?
A
- Full-thickness defect in an anatomical structure allowing protrusion of viscera
- 2 components =
- Ring (border of defect)
- Sac (mesothelial layer covering hernia contents)
2
Q
What are different types of hernias?
A
- Internal vs external
- True hernias vs false hernias / ruptures
- Spontaneous vs acquired
- Reducible vs incarcerated vs strangulated
3
Q
What is the pathophysiology of hernias?
A
- Loss of domain
-Adaptation of the abdominal wall to lower volume of contents
-Makes reduction / repair more difficult
-May cause compartment syndrome - Incarceration
-Entrapment of organs leading to luminal obstruction
-May progress to strangulation - Strangulation
-Constriction of blood supply leading to hernia contents = Torsion of vascular pedicle (esp. intestine, uterus, testicle)
-Venous drainage affected first, followed by arterial inflow
-Leads to organ necrosis and potentially rupture
-Can be acute or delayed
-Release of contents may worsen condition
4
Q
What are umbilical hernias?
A
- Due to incomplete fusion of ventral abdominal wall
- Inherited
- Often accompany other congenital defects
5
Q
What are inguinal hernias?
A
- Direct inguinal hernia = herniation through the inguinal ring adjacent to the vaginal process
- Indirect inguinal hernia = herniation into the cavity of the vaginal process
- Acquired - Relatively common, Usually middle-aged intact female dogs
6
Q
What is the aetiology of inguinal hernias?
A
- Short inguinal canal in females
- Several things may weaken / enlarge the inguinal rings =
- Oestrogen
- Malnutrition / catabolic diseases
- Obesity
7
Q
What are scrotal hernias?
A
- Indirect inguinal hernias in male dogs
- Aetiology unknown - Possibly congenital defect in inguinal ring
- Usually unilateral
- Present with pain and swelling - Incarceration / strangulation common
8
Q
What are traumatic hernias?
A
- False hernias / ruptures
- Lack a sac so more prone to adhesions / incarceration
- Can cause strangulation as ring contracts during healing
9
Q
What is aetiology of traumatic hernias?
A
- Usually blunt trauma =
- Traction / avulsion injury to abdominal wall
- Tearing of abdominal muscles close to impact
- Often coexist with severe injuries to other organ systems
10
Q
What are clinical signs of traumatic hernias?
A
- Bulging subcutaneous mass / abdominal asymmetry
- May vary in size / shape
- Clinical signs associated with other injuries
11
Q
What are incisional hernias?
A
Dehiscence of a surgical abdominal wound due to =
* Excessive force on incision -
- Obesity
- Abdominal effusion / ascites
- Activity / coughing / straining
* Poor holding strength of wound -
- Incorrect suture / knot technique
- Delayed healing due to infection, medication
12
Q
What are clinical signs of incisional hernias?
A
- Wound inflammation / oedema
- Swelling over / around wound
- Evisceration - Usually in acute hernias
13
Q
What is congenital peritoneopericardial diaphragmatic hernias?
A
- Due to failure of fusion of transverse septum resulting in midline communication between the abdomen and pericardium
- Various viscera can herniate - Causes pulmonary compression and sometimes pericardial effusion and tamponade
- Frequently coexist with other defects
14
Q
What are clinical signs of peritoneopericardial diaphragmatic hernias?
A
- May be asymptomatic / incidental finding
- Respiratory signs - Dyspnoea, tachypnoea, cough, wheeze
- GI signs - Anorexia, polyphagia, vomiting, diarrhoea, hepatic encephalopathy
- Right heart failure due to tamponade
15
Q
What are traumatic diaphragmatic hernias?
A
- Usually due to blunt trauma with glottis open
- Increased pleuroperitoneal pressure gradient causes tearing of muscle of diaphragm
- Occasionally iatrogenic due to sharp trauma
16
Q
What organs can herniate with traumatic diaphragmatic hernia?
A
- Liver
- SI / stomach
- Spleen
- Omentum
- Pancreas
- Colon
- Caecum
- Uterus
17
Q
What are clinical signs of traumatic diaphragmatic hernias?
A
- Respiratory insufficiency - Lack of functional diaphragm, Lung compression, Chest wall dysfunction, Pleural effusion, Shock
- May present several weeks after trauma
- Dyspnoea and exercise intolerance most common
- Head extended / elbows abducted
- Lethargy, weight loss and difficulty lying down
18
Q
What are perineal hernias?
A
- Due to weakness / separation of pelvic diaphragm allowing =
- Herniation into perineum
- Rectal deviation / dilatation
19
Q
What is the aetiology of perineal hernias?
A
- Inherited predisposition - Various breeds incl. border collies, boxers, poodles, OES
- Androgens - More common in older intact males, Castration reduces recurrence
- Weaker pelvic diaphragm in males
- Relaxin secreted by prostate / cysts
- Tenesmus due to prostatic, colorectal, urinary tract, anal sac or pelvic disease
- Neurogenic myopathy of pelvic diaphragm
20
Q
What are clinical signs of perineal hernias?
A
- Unilateral / bilateral perineal swelling
- Erythema / oedema / ulceration of skin
- Faecal tenesmus / pain on defaecation
- Constipation
- Flatulence
- Faecal incontinence
- Altered tail carriage
- Bladder retroflexion and dysuria
21
Q
What are indications for hernia repair?
A
- Symptomatic hernia - Pain, Inflammation, Incarceration / strangulation
- Significant protrusion affecting animal’s quality of life
- Significant risk of hollow organ incarceration / strangulation
22
Q
What are goals of hernia repair?
A
- Ensure entrapped contents remain viable
- Release / return of viable contents to their original location
- Obliteration of redundant sac
- Tension-free and secure closure of the defect
23
Q
What are different approaches to hernias?
A
- Direct (over the defect) - Uncomplicated hernias
- Ventral midline coeliotomy =
- Bilateral hernias
- Internal abdominal hernias
- Traumatic hernias
- Strangulated hernias
- Ring can be incised to aid reduction
24
Q
What are complications of hernia repair?
A
- Surgical - Usually due to poor preparation or technique =
-Anaesthetic complications
-Haemorrhage
-Contamination
-Inability to close defect
-Loss of domain
-Poor tissue strength around repair - Early postoperative - Usually due to technical errors =
-Seroma / haematoma
-Dermatitis
-Infection
-Dehiscence / evisceration
-Pain - Late postoperative
-Sinus tracts / enterocutaneous fistulae
-Recurrence
25
Q
How can you prevent complications of hernia repairs?
A
- Preoperatively =
- Prepare / stabilise patient, resolve predisposing factors
- Understand anatomy and possible complications
- At surgery =
- Correct technique / use of tissues for closure
- Postoperatively =
- Control patient
- Recognise / treat complications
- Eliminate factors putting pressure on repair
26
Q
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