Abdominal Wall Reconstruction and Hernias Flashcards
What is an auto-penetrating hernia?
A traumatic abdominal wall hernia caused by a fractured rib penetrating through abdominal musculature
In the cranial, middle and caudal thirds of the abdomen, which aponeuroses are sitting superficial and deep to the rectus abdominis?
Cranial:
- External Abdominal Oblique - Superficial
- Internal abdominal oblique - Both
- Transverse Abdominis - Deep
Middle
- External Abdominal Oblique - Superficial
- Internal Abdominal Oblique - Superficial
- Transverse Abdominus - Deep
Caudal
- All superficial
Where do the internal and external abdominal obliques and the transverse abdominis originate from?
External abdominal oblique
- Originates from 4/5th to 12th rib and from last rib and thoracodorsal fascia
- Runs in caudoventral direction
Internal Obdominal oblique
- Originates from thoracolumbar fascia caudal to last rib and from tuber coxae
- Runc cranioventrally
Transverse Abdominis
- Lumbar portion arising from the transverse processes of the lumbar vertebrae and thoracolumbar fascia
- Costal portion - Arising from medial sides of 12th and 13th rib as well as 8th-11th costal cartilages
- Runs in dorsoventral direction
What are substernal midline defects often associated with?
- Congenital peritoneal pericardial diaphragmatic hernia
- PPDH often assoc with incompletely fused caudal sternebrae
List methods of explansion used in human surgery for loss of domain
- Progressive pneumoperitoneum
- Silastic expanders
- Staged reduction
- Prosthetic material
How can intestinal strangulation lead to rapid systemic illness?
- Bacterial transmigration
- Vasoactive substances release (arachidonic acid metabolites, cytokines, leucotrienes, kinins) from tissue and blood cell autolysis
- Redistribution of fluids and severe cardiopulmonary effects
What is the embryological cause of ventral abdominal wall hernias?
Failure of fusion or delayed fusion of the lateral folds (primarily the rectus abdominis)
What disorders have been associated with congenital ventral abdominal hernias?
- Fucosidosis
- Ectodermal dysplasia
- Cryptorchidism
What initially protects and omphalocoele?
A thin transparent membrane of amniotic tissue
What is gastroschisis?
A congenital ventral abdominal hernia, very similar in appearance to an omphalocoele but it is paramedian
What breeds are predisposed to umbilical hernias?
- Airedale terriers
- Basenjis
- Pekingese
- Pointers
- Weimeraners
What are the 2 broad classifications of inguinal hernias?
- Indirect - hernia contents enters the cavity of the vaginal process
- Direct - Hernia contents pass through the inguinal ring adjacent to the vaginal process (less common)
Are inguinal hernials common?
- Congenital is rare
- Acquired is common
Describe the anatomical boundaries of the inguinal rings?
- Internal inguinal ring: Bound by rectus abdominis, inguinal ligament and internal abdominal oblique
- External inguinal ring: Longitudinal slit in the aponeurosis of the external abdominal oblique
What structures pass throught the inguinal canal?
- Genital branch of genitofemoral nerve, artery and vein
- Cremaster muscle passes through external ring
- Pass through the caudomedial aspect
Which breeds have been shown to have heritable inguinal hernias?
- Golder Retrievers
- Cocker Spaniels
- Dachshunds
List factors which may predispose an animal to an inguinal hernia
- Bitches have a shorter and wider inguinal canal
- Most commonly occur during aestrus in intact bitches, suggesting oestrogen has a close association (changing strength and character of connective tissue)
- Associated between inguinal and perineal hernias in male dogs
- Obesity (accumulation of fat around the round ligament)
List some differentials for an inguinal hernia
- Soft tissue maass
- Mammary tumour or cyst
- Lipoma
- Enlarged LN
- Abscess
- Haematoma
- Testicular torsion/abscee/neoplasia
- Orchitis
List closure options for an inguinal hernial which cannot be primarily closed
- Polypropylene mesh onlay
- Sartorius muscle flap
Why is castration recommended after a scrotal hernia?
- Reduce recurrence
- Prevent offspring (may be heritable)
- Increased risk of testicular neoplasia
- Testicular necrosis
Where is the femoral canal located in relation to the inguinal canal?
Lateral to the inguinal ligament (caudolateral to inguinal canal)
What are the two lacunae of the femoral canal?
- Muscular lacunae - Femoral nerve within iliopsoas muscle
- Vascular lacunae - Craniolateral to muscular lacunae and contains femoral artery and vein and saphenous nerve
- Iliopectineal arch (iliac and transverse fascia) seperated the lacunae.
Where does herniation tend to occur in femoral hernias?
- In the femoral canal; a potential space caudomedial to the femoral vessels
Broadly speaking, how do you correct femoral hernias?
- Intra-abdominal closure of the hernia sac
- Extra-abdominal reconstruction of the hernia ring
List options for repair of a cranial pubic ligament avusion if primary repair is not possible
- Hole into pubis
- Rectus abdominis flap
- Sartorius flap
What are the 2 borad causes of incisional hernia?
- Excessive force on incision
- Poor holding strength of the wound
What is the suture-to-wound length ratio fo abdominal wall closure?
What are the recommended suture bites?
- 4:1 ratio
- Equates to 5-7mm fascial bites with 3-4mm of travel
What is the most consistent sign of impending abdominal wall dehiscense?
Swelling and serosanguinous drainage from the incision
Is debridement recommended for treatment of acute incisional hernia?
Not unless fascial edges are devitalised, infected or unidentifiable
Contraindicated as it caused excessive and unnecessary tissue trauma and set the wound back to its substrate phase, delaying the onset of rapid fascial strength gain
List some autologous repair methods for large abdominal wall defects
- Vacuum assisted closure
- Separation of anatomic components (fascial releasing incision and adjacent tissue transfer)
- Abdominal wall partitioning (multiple parasagittal releasing incisions in staggered pattern)
- Cranial sartorius muscle flap (branch of femoral artery and vein at proximal third)
- External abdominal Oblique muscle flap (cranial branch of cranal abdominal artery supplies middle zone of lateral abdominal wall)
- Rectus abdominis muscle flap (cranial and caudal epigastric vessels)
List some nonautogenous repair methods for large abdominal wall defects
- Synthetic mesh (polypropylene - inert, woven, monofilament, porous)
- Tissue grafts or bioprosthetic mesh (porcine SIS)
What are the three methods of mesh placement?
Which is most commonly used?
- Overlay
- Interposition
- Underlay
Underlay most often used, lowest rate of reherniation and wound complications
- Better distribution of tension
- Superior formation of post-op connective tissue
- Sliding myofascial flaps or adjacent adipodermal flaps placed over and underlay mash provide another later of mechanical buttress and barrier from infection
- Underlying omental patch to minimise adhesions
