Surgery 3 Flashcards
What affects the choice of suture material?
- The wound
- The body
- The surgeon
What are the requirements of the wound regarding suture choice?
- Maintain adequate strength until purpose is served (e.g. tendon needs support for longer vs mucosa)
- Stimulate minimal tissue reaction
- Must be absorbed at a dependable rate, or become encapsulated without complications
- Must consider: tensile strength of wound, bacterial charge of wound, current or planned therapies for the wound
What are the requirements of the body regarding suture choice?
- Must be non-electrolytic
- Non-capillary
- Non-allergenic
- Non-carcinogenic
What are the requirements of the surgeon regarding suture choice?
- Must be easy to use
- Minimal tissue drag
- Good knot security
- Inexpensive
- Easily available
- Easily sterilised without alteration
What is tensile strength?
Breaking strength per unit area
What is suture memory?
The tendency to retain is original configuration, is not a good handling characteristic and will not tie good knots
What is tissue drag or chatter?
Lack of smoothness or friction whilst passing through tissue
What are the recommended and possible suture materials for skin?
- Recommended: Monofilament non-absorbable materials e.g. Monosol, surgipro
- Possible: absorbable, Polysorb (braided) or Biosyn (monofilament)
What are the recommended and possible suture materials for muscle?
- Recommended: absorbable braided e.g. Polysorb
- Possible: absorbable monofilament Biosyn
What are the recommended, possible and contraindicated suture materials for bladder, uterus and digestive tract?
- Recommended: absorbable monofilament Biosyn, PDS
- Possible: absorbable braided (polysorb)
- Contraindicated: non-absorbable monofilament monosol
What are the recommended and possible suture materials for kidney and liver?
- Rec: absorbable mono Biosyn
- Poss: absorbable braided Polysorb
What are the possible suture materials for hernias?
- Absorbable braided Polysorb
- Non-absorbable braided (e.g. surgidac)
- Non-absorbable mono e.g. Surgipro
What are the recommended and possible suture materials for tendons?
- Non absorbable
- Rec: Braided e.g. surgidac, mono e.g. surgipro
- Poss: mono e.g. monosol
What are the recommended and possible suture materials for the articular capsule?
- Rec: non-absorbable braided e.g. surgidac
- Poss: non-absorbable mono e.g. surgipro
What is the recommended suture material for vascular surgery?
Non-absorbable monofilament e.g. surgipro
What are the recommended, possible and contraindicated suture materials for contaminated tissue?
- Rec: non-absorbable mono e.g. surgipro
- Poss: non-absorbable mono e.g. monosol
- Contra: non-absorbable braided e.g. surgidac
What suture material can be used with drains?
Non-absorbable monofilament e.g. surgipro
What suture material is recommended for surgery of the oral cavity and procedures where prolonged support is not needed?
- Absorbable monofilament
- e.g. Caprosyn
How is ischaemia due to sutures avoided?
- Sufficiently spaced suture bites
- Tightened without excess
- As little dead space as possible
When are surgeon’s knots required?
- When the wound is under lateral tension
- Prevents knot coming undone between the first and second throw due to increased friction
- There is no difference in stability of the final knot, only the stability of the first throw is altered
What affects the number of throws required on a suture?
- The material used
- the tissue the sutures are being placed in
- e.g. materials with higher memory typically need more throws than those with poor memory (except polypropylene)
What affects the knot security of a suture?
The surface frictional characteristics of the material (mono vs multifilament)
When might slip knots be used?
When typing a ligature deep in a cavity, but must be locked properly into a square knot
Name the common interrupted patterns for skin closure
- Simple interrupted
- Cruciate mattress
- Horizontal mattress
- Vertical mattress
Name the common continuous suture patterns
- Simple continuous
- Subcuticular
- Ford interlocking
- Cushing
- Connel
- Lembert
Outline the use of a horizontal mattress suture
- Common in large animal, rare in small animal
- Produces everting suture, historical argument as wounds heal from dermis up so aim was to appose dermis
- Produces messy wound
OUtline the use of Cushing, Connel and Lembert sutures
- Inverting sutures
- Commonly used for bowel surgery and cesareans when closing the uterus
- Appose the serosal layers
What is the Aberdeen knot used for?
Typing off a simple continuous pattern
What are the principle causes of suture dehiscence?
- Knot slippage
- Knot breakage
- Tissue laceration
- Weakening of the suture during its handling e.g. crushing, shearing
Discuss the use of skin staples
- Painful and irritating but quick to apply
- Useful for long wounds
- Useful where some interrupted sutures have been pulled out by animal and need to quickly top up sutures to hold wound together
What are the principles in cytological sample examination?
- Low power first to find area of interest
- Consider quality of preparation
- Identify the background
- Identify the predominant cell type
- Examine other cells present at 40x magnification
What may be seen in the background of a cytological slide?
- Haemorrhage
- Granules
- Protein
- Matrix
- Debris
- Disrupted cells
What can be inferred from the predominant cell type on a cytological slide?
If neutrophils are the predominant cell type then the lesion is likely to be inflammatory rather than neoplastic
What are the potential causes of lumps?
- Inflammation
- Neoplasia
- Cysts
What are the different types of inflammatory lumps?
- Can be neutrophilic, eosinophilic, lymphoplasmacytic, granulomatous
- Acute or chronic
- Septic or aseptic
What are the different types of neoplastic lumps?
- Benign or malignant
- Epithelial, round, sindle/mesenchymal cells
What are the different types of cystic lumps?
- Haematoma
- Seroma
- Sialocoele
- Epithelial/follicular
Describe the appearance of acute inflammation on cytology
- > 70% of nucleated cells are neutrophils
- Rest may be mononuclear cells
- Can be septic or aseptic
Describe the characteristics of aseptic acute inflammation on cytology
- Neutrophils predominate but are well preserveed
- In tact neutrophils with compact chromatin
- A few macrophages and lymphocytes
- No bacteria visible
Describe the characteristics of septic acute inflammation on cytology
- Neutrophils are degenerate (karyolysed)
- Bacteria often present
- Neutrophils appear swollen and pale
Describe the characteristics of eosinophilic inflammation on cytology
- Cell content may be mixed
- 50% or more are eosinophils
Describe the characteristics of chronic inflammation on cytology
- Number of mononuclear cells is increased and may be >50% of nucleated cells
- Recruit other cell types, in particular macrophages
Describe the characteristics of granulomatous inflammation on cytology
- Chronic inflammation from persistent irritation/infection with particular organisms e.g. staphylococci and fungi
- Characterised by presence of multinucleated giant cells (Langhans type cell)
Describe the characteristics of cysts on cytology
- Vary widely in aetiology and therefore contents of aspirate smear
- May be aceullar and watery or filled with proteinaceous content, or with necrotic material or keratin debris
- In hair follicles are likely to get keratin flakes building up and blocking gland
- Keratin breakdown over time produces sharp edged cholesterol crystals
Describe the characteristics of a sialocoele on cytology
- Smears contain many RBCs, few WBC, clouds of pink amorphous mucin and many macrophages
- Collections of epithelial cells, stick together
- Cytoplasm filled with pink mucin to be released
What are sialocoeles and how do they occur?
- Firm painless fluid swelling of acute onset in the submaxillary space
- Caused by blocked salivary gland, continuous production of saliva but cannot be removed so end up with a collection of cells in large volume of fluid
Describe the characteristics of a haematoma on cytology
- Fluid blood-like, dark, does not clot
- Cell counts/protein content similar to blood but no platelets unless still actively bleeding
- Macrophages clearing red cells
- Haemosiderophages may be seen
- Breakdown products of haemoglobin may be seen, initially light blue then haematoid produced (yellow)
What are the different types of epithelial neoplasia?
- Surface: squamous, basal, transitional, hair follicle
- Glandular: apocrine, exocrine
Describe the characteristics of epithelial neoplasia on cytology
- High yield on FNA/FNCS
- Cells associated with one another
- Found in rafts/sheets/acini
- Cuboidal or columnar shape of cells
- Cobblestone street pattern
- Can see white lines between cells
What are benign epithelial tumours called?
- Surface: papilloma
- Glandular: adenoma
What are malignant epithelial tumours called?
- Surface: carcinoma
- Glandular: adenocarcinoma
What are the cell types of spindle/mesenchymal neoplasia?
- Fibrocyte
- Muscle cells
- Osteoblasts
- Endothelial cells
What are malignant spindle/mesenchymal tumours called?
- Suffixed with sarcoma
- e.g. fibrosarcoma, haemangiosarcoma
What are benign spindle/mesenchymal tumours called?
- E.g. fibroma
- Leiomyoma
Describe the characteristics of spindle/mesenchymal neoplasias
- Low cytological yield on FNA/FNCA
- Spindle shaped cells seen
- Usually single but may be in association/sheets
- May be in matrix
- Shape of cell difficult to make out, ends tail off
What are the potential cell types for round cell neoplasia?
- Lymphocytes
- Mast cells
- Histiocytes
- Plasma cells
What are benign round cell tumours called?
- Histiocytoma
- PLasmacytoma
What are malignant round cell tumours called?
- Lymphoma
- Mast cell tumour
- Malignant myeloma
Describe the characteristics of round cell neoplasia of cytology
- High yield on FNA/FNCS
- Discrete round cells with obvious border
- Not adherent to each other
Describe the general characteristics of a benign neoplasia on cytology
- Cells all look similar to each other
- Nuclear size within 1.25x of each other
- Little variation in tissue where there should be, and lots of variation in tissues where there should be (e.g. lymph nodes should have variety of lymphocytes)
Describe the cytological characteristics of benign epithelial neoplasias
- Single population of uniform, large cells
- Pale, mildly granular cytoplasm
- Round to oval nuclei
- Fine lines between cells and cobblestone pattern indicating epithelial cells
Describe the cytological characteristics of benign round cell neoplasia
- Single population of uniform cells
- Moderate, pale cytoplasm
- Round to oval nuclei
Describe the cytological appearance of a lipoma
- Soft, smooth, slow growing
- Non-nodular, painless masses
- Aspirate is clear and greasy, poor staining with Diff-Quick
- Stains with Sudan III or oil red “O”
- Low cellularity, few clumps of benign connective tissue cells and adipocytes
What are the cytological criteria of malignancy?
- Cellular
- Nuclear
- Cytoplasmic
Describe the cellular criteria of malignancy
- Cells alien to position found in
- Pleomorphism where there shouldnt be
- Monomorphic cell population where there should be variation
- High and/or variable nuclear to cytoplasm ratio
Describe the nuclear criteria of malignancy
- Variation in shape/size (ratio of smallest to largest diameter of >1.5x is bad news)
- Multiple, fragmented or moulded nuclei
- Clumped chromatin
- Multiple/irregular nucleoli
- Increased/abnormal mitotic figures
What causes the flattening or moulding of nuclei in malignant neoplasia?
Rapid growth of adjacent cells
Describe the cytoplasmic criteria of malignancy
- Basophilia/hyperchromasia (more blue, higher RNA content of immature and active cells)
- Vacuolation, granularity, phagocytosis of other cells
- Pseudopod formation in some cases
Describe the cytological appearance of epithelial carcinomas
- High cellularity
- Rounded or cells with distinct border, cluster/sheet/acini
- Acini imply adenocarcinoma
- Mitotic figures
Describe the cytological appearance of mesenchymal sarcomas
- Low cellularity
- Single, elongated/spindle-shaped cells with indistinct cell boundaries
- Difficult to identify specific cell of origin
Describe the cytological appearance of round cell tumours
- Cellularity high
- Rounded or oval cells with distinct border, singly or in small clusters
- Multiple nucleoli, little variation in cell type in lymphoma
- In mast cell tumour, lots of cellular variation
What may cause lymph node enlargement?
- Reactive hyperplasia
- Lymphadenitis
- Lymphoma
- Metastatic neoplasia
Describe the appearance of a metastatic neoplasia in a lymph node
- Presence of “alien” cells
- e.g. epithelial cells
What cytological finding would indicate lymphadenitis?
Neutrophils (inflammation)
Describe the cytological appearance of a liver FNA
- Hepatocytes large, round or oval cells
- Abundant, finely granular cytoplasm
- Nuclei have coarse chromatin and prominent nucleolus
What material and needle is used for subcuticular pattern sutures?
- Absorbable monofilament
- Swaged to a sharp cutting needle
Outline the procedure for a subcuticular suture pattern
- Knot suture to subcutaneous tissues at the start of the wound commissure
- Cut end
- Start passage of needle from commissure through subcuticular tissue, then to the other side just back from where first stitch exited
- Take alternating bites of tissues on opposite sides of wound, each time slightly back from where needle exited
- Final passage of needle towards wound creates loop used for Aberdeen knot to tie off the suture
- Pass needle back through wound, exit some distance from commissure to bury knot
- Cut end and bury in the skin
When can male rodents be castrated?
As soon as their testicles have descended
What approaches can be used for castration of male rabbits?
Scrotal or prescrotal approach
What approach is used for the castration of male guinea pigs?
Prescrotal
What approaches can be used for the castration of male rats?
Abdominal, scrotal or prescrotal
What is an important consideration when castrating male rodents and rabbits?
- Open inguinal canal
- May withdraw testes prior to surgery
- Can be exteriorised by applying gentle pressure on the caudal abdomen
Why is a subcuticular pattern commonly used in rodents and rabbits?
Are good at removing sutures
What suture material should be used in the castration of rodents and rabbits?
- Ideally synthetic materials
- 3-0 absorbable for rabbits and larger rodents
- 4-0 for smaller rodents
