ONCOLOGY - Surgery Flashcards
Which factors should you consider before proceeding with oncological surgery?
- What is the histologic type, grade and stage of neoplasia?
- What are expected local and system effects of this type, grade and stage of neoplasia?
- Is treatment possible and what are the cosmetic and functional costs?
- Is oncological surgery indicated at all?
- What are the alternative or combined treatment options?
What are the principles of oncological surgery?
- Resect the tumour with appropriate margins
- Plan the biopsy in a way that allows for the biopsy tract to be resected with the tumour
- Consider all scars from previous surgeries, biopsies and drains and ensure they are resected with the tumour (assume all scar tissue has neoplastic tissue within it and resect with appropriate margins)
- Ligate the blood supply early to prevent dessication
- Limit contamination of the surgical field
- Limit the use of drains
What are the different biopsy techniques?
Fine needle aspirate (FNA)
Core needle biopsy
Incisional biopsy
Excisional biopsy
What information can be obtained from a fine needle aspirate (FNA)?
Cell type present
What are the main advantages of a fine needle aspirate (FNA)?
Fine needle aspirates (FNA) are quick, cheap and easy
What are the main disadvantages of a fine needle aspirate (FNA)?
A fine needle aspirate (FNA) is does not provide a definitive diagnosis as only the cells can be examined and thus you cannot examine how the tumour is interacting with the surrounding tissues
What are the main advantages of a core needle biopsy?
A core needle biopsy preserves tissue architechture and thus can be used for histological diagnosis
What are the main disadvantages of a core needle biopsy?
A core needle biospy requires general anaesthetic
What are the two types of needle used for a needle core biopsy?
Tru-cut needle
Jamshidi needle
When is a tru-cut needle most approproate for a needle core biopsy?
A tru-cut needle is used for a soft tissue biopsy
When is a Jamshidi needle most appropriate for a needle core biopsy?
A Jamshidi needle is used for a bone/bone marrow biopsy
What is an incisional biopsy?
An incisional biopsy is where a wedge of tissue is excised, ideally with a margin of abnormal and normal tissue, making sure to plan the incison so the biopsy tract can be resected with the mass eventually
What is an excisional biopsy?
An excisional biopsy is where the whole mass is resected with an appropriate margin
What are the two classifications of margins of excision?
Radial margin
Deep margin
What are radial margins of excision?
The radial margins of excision consists of the skin and associated fat excised radial to the mass
What are deep margins of excision?
The deep margins of excision refer to the degree of excision in the tissues deep to the mass
What are the different classifications of tumour resection?
Marginal resection
Local resection
Wide local resection
Radical resection
What is a marginal resection?
A marginal resection is tumour excision with a 1 - 2mm radial margin
Which tumours are marginal resections appropriate for?
Benign, non-invasive tumours such as lipomas
What is a local resection?
A local resection is tumour excision with a 1cm radial margin and a deep margin down to the first fasial plane
Which tumours are local resections appropriate for?
Benign, non-invasive tumours such as mammary tumours or histiocytomas
What is a wide local resection?
A wide local resection is tumour excision with a 2 - 3cm radial margin and a deep margin excising the deep fascial plane
May require referral
Which tumours are wide local resections appropriate for?
Wide local resections are used for sarcomas and mast cell tumours
What is a radical resection?
A radical resection is a tumour excision with a 3 - 5cm radial margin and a deep margin excising 1 to 2 deep fascial planes, or amputation
Generally will require referral
Which tumours are radical resections appropriate for?
Very locally aggressive tumours
What are the indications for a splenectomy?
Splenic mass
Splenic neoplasia
Splenic haematoma
Trauma
What is the most common splenic neoplasia?
Splenic haemangiosarcoma
How do you carry out a splenectomy?
- Laprotomy incision
- Gently locate and exteriorise the spleen, identifying the hilus
- Move from the tail to the head of the spleen and double ligate the hilar vessels close to the hilus
- Cut between the ligatures
- Flush the abdomen with 100 - 200ml/kg of sterile isotonic saline
- Routine abdominal closure
- Send the spleen for histopathology
- Make sure to biopsy any lesions identified during surgery (i.e. any liver lesions)
What are Halstead’s principles of surgical technique?
Strict adherence to aspectic technique
Gentle tissue handling
Sharp anatomic dissection of the tissues
Miticulous haemostasis
Obliteration of dead space
Avoidance of tension
How do you ensure strict adherence to aseptic technique?
Aseptic patient, surgeon and surgical instrument preparation
Appropriate surgical clipping and draping
Perioperative antibiotics
Cover wounds post-operatively until the patient leaves the practice
When are perioperative antibiotics indicated?
Perioperative IV antibiotics are indicated if the surgery exceeds 90 minutes, and should be repeated every 90 minutes
Which antiobiotic is typically used for perioperative antiobiotic administration?
Cefuroxime
Why is gentle tissue handling so important?
Gentle tissue handling is so important as tissue trauma can cause inflammation and increase the risk of infection and wound dehiscence
How do you ensure gentle tissue handling?
Use appropriate surgical instruments
Keep tissues moist to avoid tissue dessication
Use stay sutures to manipulate the skin edges
How do you ensure sharp anatomical dissection of the tissues?
Make sure to use a scalpel where possible over blunt dissection. When blunt dissection is required, use metzenbaum scissors as these are much sharper than mayo scissors
How do you maintain meticulous homeostasis?
Use haemostats to control bleeding
Use diathermy if available
Dap tissues with swabs to remove the blood rather than wipe the tissues
What is diathermy?
Diathermy is the use of heat from an electrical current to seal off bleeding vessels
How can you obliterate dead space?
Careful tissue dissection
Use sutures to close the dead space (i.e. walking sutures)
Surgical drains
What are the two forms of surgical drains?
Open passive surgical drains
Closed active surgical drains
How do open, passive surgical drains work?
Open, passive surgical drains rely on gravity and the natural flow of fluids to drain fluid from the body.
Give an example of an open passive surgical drain
Penrose surgical drain
How do you place an open, passive surgical drain?
If using a penrose drain, insert the drain into the surgical wound or cavity, making sure the drain is position to allow for passive drainage of any fluid that may accumulate. This is typically at a lower point where fluid tends to collect, typically at the most dependent part of the wound or cavity. Anchor the drain internally. The drain should exit the body at a point distant from the surgical site through a stab incision in the skin. Use sutures to secure the drain to the skin near its exit point
How do you manage an open passive surgical drain?
- Cover the drain with a dressing while the patient is in the clinic (this dressing can usually be removed once the patient goes home)
- Make sure to put buster collars on dogs with drains as they will eat the drain
- Monitor the fluid volume accumulating within the dressing, and when it begins to reduce (usually between 2 to 5 days), the drain can be removed
How do closed, active surgical drains work?
Closed, active surgical drains rely on a vacuum to drain fluid from the body
Give an example of a closed, active surgical drain
Jackson Pratt surgical drain
How do you place a closed, active surgical drain?
If using a Jackson Pratt drain (which consists of a flexible tibe connected to a bulb which will create suction), insert the tubing into the surgical wound or cavity. The drain should exit the body at a point distant from the surgical site through a stab incision in the skin. Secure the tube to the skin with a Chinese dinger trap suture near its exit point. Compress the bulb/collection chamber and attach it to the tubing to generate a vacuum
How do you manage a closed active surgical drain?
- Make sure to dress the skin interface
- Monitor the fluid volume accumulating within the dressing, and when it begins to reduce (usually between 2 to 5 days), the drain can be removed
What is the main benefit of a closed active drain over an open passive drain?
A closed active surgical drain is a closed system so there is a reduced risk of infection compared to an open, passive surgical drain
Why is it so important to avoid tension when closing wounds?
If the wound it under tension, this increases the risk of wound dehiscence and the wound will be more uncomfortable for the animal
How can you avoid wound tension?
Incise parallel to tension lines
Close the wound in layers
Undermining
Use tension distributing sutures
Skin flaps and grafts
What are tension lines?
Tension lines are lines of tension created by the linear arrangements of fibrous tissue in the dermis
What are the benefits of closing incisions in layers?
Closing incisions in layers distributes the tension as well as reduces dead space
What is undermining?
Undermining is the careful seperation of the skin from the underlying layers to create more mibility and reduce tension. It is important to undermine below the cutaneous trunci muscle or the subcutaneous fat to reduce the blood supply
Which suturing techniques can be used to relieve tension on wounds?
Walking sutures (very painful)
Cruciate
Horizontal mattress
Vertical mattress
Far-near-near-far
Far-far-near-near
What are ‘dog ears’?
‘Dog ears’ are puckered areas of skin which can form where two skin edges meet during wound closure. This is a cosmetic issue which will flatten with time
What can be done to prevent ‘dog ears’?
Make elliptical incisons
Incise parallel to the tension lines
What are advancement skin flaps?
Advancement skin flaps are a technique used to close wounds by advancing adjacent skin over the wound
How do you carry out an advancement skin flap?
Ensure there is enough skin adjacent to the wound. Incise appropriately and undermine the skin. Advance the skin flap over the deficit and suture it in place
What is an H-plasty?
An H-plast is an advancement skin flat using two smaller flaps adjacent to the deficit
What are axial pattern flaps?
This is referral surgery
Axial pattern flaps are large, very robust skin flats which have their own direct cutaneous artery and vein at their base, and can be maneuvered large distances
What are skin grafts?
Skin grafts are where a piece of skin is removed and attached to a completely different area of the body, and develps a blood supply from the a healthy bed of granulation tissue
Where is a skin graft usually taken from?
Thoracic wall
How do you manage a skin graft?
A skin graft must be completely immobile to revascularise. Bandages and external skeleton fixators can be used to achieve this
What should you do if you are unable to close a wound?
If you are unable to close a wound, dress the wound and seek help. DO NOT attempt to close a wound under too much tension as these wounds will be very painful, fail and if on limbs can cause a tourniquet and limb loss
