Membership of the Royal College of Surgeons (MRCS) Principles of Surgery-in-General Syllabus

Which four phases describe normal wound healing and their approximate timelines?

Haemostasis (immediate, minutes), Inflammation (day 0–~5), Proliferation (days ~3–21: granulation, angiogenesis, epithelialisation), and Remodelling/Maturation (weeks to ~1–2 years). Phases overlap.

What is the difference between healing by primary, secondary, and tertiary (delayed primary) intention?

Primary: clean wound edges apposed directly (e.g. sutured incision), minimal scar. Secondary: wound left open to granulate and contract (e.g. abscess cavity), larger scar. Tertiary: wound left open initially (e.g. for contamination) then closed surgically a few days later.

What is the maximum tensile strength a healed wound regains, and when does it reach ~80%?

A healed wound regains only about $80\%$ of original (unwounded) tensile strength at best. At ~$1$ week it has ~$10\%$, at $3$ weeks ~$20\%$, reaching peak strength over many months during remodelling.

What is the surgical classification of operative wounds (CDC) and the approximate infection risk of each?

Clean ($<2\%$); Clean-contaminated, controlled entry into viscus ($<10\%$); Contaminated, gross spillage/acute inflammation ($\sim 15\text{–}20\%$); Dirty, established infection/perforation ($\sim 40\%$).

List key local and systemic factors that impair wound healing.

Local: infection, ischaemia/poor blood supply, foreign body, haematoma, tension, radiation. Systemic: diabetes, malnutrition (low protein, vitamin C/zinc deficiency), steroids/immunosuppression, smoking, old age, jaundice, malignancy.

How is a chronic wound defined and name three common types.

A wound failing to progress through orderly healing within ~$4\text{–}6$ weeks (or not healed by ~$3$ months). Common types: venous leg ulcers, arterial ulcers, diabetic neuropathic (foot) ulcers, and pressure ulcers.

Compare the typical features of venous versus arterial leg ulcers.

Venous: gaiter area (medial malleolus), shallow, exudative, irregular edge, painless, with haemosiderin/lipodermatosclerosis; treated with compression. Arterial: distal/pressure points (toes, heel), 'punched-out', deep, painful, pale base, absent pulses; compression contraindicated.

What is the difference between a hypertrophic scar and a keloid scar?

Hypertrophic scar: raised but stays within the boundaries of the original wound, often regresses with time. Keloid: extends beyond the original wound margins, does not regress, more common in darker skin and on sternum/ear lobes/shoulders; high recurrence after excision.

What is the 'reconstructive ladder' in plastic/reconstructive surgery?

A graded approach from simplest to most complex: secondary intention → primary closure → skin graft → local/random flap → regional/pedicled flap → free (microvascular) tissue transfer. Choose the simplest option that meets the defect's needs.

What is the difference between a skin graft and a flap?

A graft (split- or full-thickness skin) is detached tissue with no intrinsic blood supply, surviving initially by imbibition then revascularisation from the recipient bed. A flap carries its own blood supply (pedicle) and can cover poorly vascularised beds (bone, tendon).

How does a split-thickness skin graft (SSG) differ from a full-thickness graft (FTSG)?

SSG: epidermis + part of dermis; takes more readily, covers large areas, but contracts more and gives poorer cosmesis. FTSG: epidermis + entire dermis; less contraction, better colour/texture match (good for face), but needs a well-vascularised bed and limited donor size.

State key physiological differences making paediatric patients vulnerable in surgery/trauma.

Higher surface-area-to-volume ratio (rapid heat/fluid loss), larger relative blood volume but smaller absolute reserve, compensate shock with tachycardia (hypotension is a late sign), higher metabolic/oxygen demand, and larger occiput/relatively large tongue affecting airway.

What is the Holliday–Segar '4-2-1' rule for paediatric maintenance fluid rate?

$4$ mL/kg/h for the first $10$ kg, $+2$ mL/kg/h for the next $10$ kg, $+1$ mL/kg/h for each kg above $20$ kg. E.g. a $25$ kg child: $40 + 20 + 5 = 65$ mL/h.

How is a child's estimated circulating blood volume calculated, and the paediatric trauma fluid bolus?

Estimated blood volume $\approx 70\text{–}80$ mL/kg. Trauma resuscitation bolus is $10\text{–}20$ mL/kg of crystalloid (or $10$ mL/kg blood), reassessing after each bolus.

Why are elderly surgical patients at higher operative risk — give the key reasons.

Reduced physiological reserve in all organ systems, multiple comorbidities and polypharmacy, frailty, impaired thermoregulation, atypical presentation (e.g. afebrile sepsis), higher delirium risk, poor nutrition, and reduced ability to compensate for blood/fluid loss.

What frailty/risk assessment tools are commonly applied to the elderly surgical patient?

Clinical Frailty Scale (Rockwood), and risk scores such as P-POSSUM, ASA grade, and the Charlson Comorbidity Index; comprehensive geriatric assessment (CGA) is increasingly used pre-operatively.

What physiological changes in pregnancy alter the surgical/trauma assessment?

Increased plasma volume and cardiac output with physiological anaemia, lower baseline BP, raised HR; aortocaval compression after ~$20$ weeks (nurse in left lateral tilt $\geq 15^{\circ}$); reduced functional residual capacity and rapid desaturation; delayed gastric emptying (aspiration risk).

In trauma during pregnancy, why is maternal resuscitation the priority, and what is the tilt manoeuvre?

'The best treatment for the fetus is to resuscitate the mother.' From ~$20$ weeks, manual left uterine displacement or a $15\text{–}30^{\circ}$ left lateral tilt relieves aortocaval (IVC) compression by the gravid uterus, restoring venous return and cardiac output.

How is body mass index (BMI) calculated and what value defines obesity?

$$BMI = \frac{\text{weight (kg)}}{[\text{height (m)}]^{2}}$$ Obesity is $BMI \geq 30$ kg/m$^2$; morbid obesity $\geq 40$ (or $\geq 35$ with comorbidities). Obesity raises risks of VTE, wound infection, difficult airway, and respiratory complications.

Name three classic surgical incisions and their typical use.

Midline laparotomy (versatile access to whole abdomen, relatively avascular linea alba); Kocher's subcostal (open cholecystectomy/biliary); Gridiron/Lanz at McBurney's point (open appendicectomy); Pfannenstiel (pelvic/Caesarean, good cosmesis).

What is Langer's lines and why is it relevant to incision planning?

Langer's lines are the natural orientation of dermal collagen fibres (lines of skin tension). Incisions made parallel to them heal with less tension and produce finer, cosmetically better scars; crossing them risks wider/hypertrophic scarring.

How do monopolar and bipolar diathermy (electrosurgery) differ?

Monopolar: current passes from an active electrode through the patient to a return (plate) electrode — versatile for cutting and coagulation but greater stray-current risk. Bipolar: current passes only between the two tips of forceps — safer, precise, ideal near nerves/end-arteries and in patients with pacemakers.

What are 'cutting' versus 'coagulation' diathermy waveforms?

Cutting uses a continuous low-voltage waveform producing high local heat that vaporises cells. Coagulation uses an interrupted (pulsed) high-voltage waveform that heats tissue more slowly to cause protein denaturation and seal vessels. 'Blend' combines both.

Name common energy/haemostatic devices and their principle of action.

Diathermy (electrical heat); Harmonic scalpel (ultrasonic vibration, ~$55.5$ kHz, denatures protein at lower temperature, less smoke); LigaSure (bipolar vessel sealing of vessels up to ~$7$ mm); Argon plasma coagulation (non-contact, ionised argon for surface bleeding); plus topical agents and ligation/clips.

What is the WHO Surgical Safety Checklist and its three phases?

A checklist to reduce surgical errors with three phases: 'Sign In' (before induction of anaesthesia), 'Time Out' (before skin incision — confirm patient, site, procedure), and 'Sign Out' (before patient leaves theatre — count instruments/swabs, specimen labelling).

How are surgical complications classified by timing, and give the Clavien–Dindo grading concept.

By timing: immediate ($<24$ h), early (days–weeks), late (months–years). Clavien–Dindo grades severity by treatment needed: I (no intervention), II (drugs/transfusion), III (surgical/radiological/endoscopic intervention), IV (life-threatening, ICU), V (death).

What are the key imaging modalities and the principle each uses to form an image?

X-ray/CT: differential absorption of ionising radiation (X-rays). Ultrasound: reflection of high-frequency sound waves (no ionising radiation). MRI: behaviour of hydrogen protons in a strong magnetic field/radiofrequency pulses (no ionising radiation). Nuclear medicine/PET: detection of emitted gamma radiation from radiotracers.

Which imaging is first-line for suspected: (a) free intraperitoneal air, (b) gallstones, (c) acute aortic dissection, (d) suspected stroke?

(a) Erect chest X-ray / CT for free air under diaphragm; (b) Ultrasound for gallstones; (c) CT angiogram for aortic dissection; (d) non-contrast CT head first (to exclude haemorrhage), then MRI for ischaemia.

What is the FAST scan and what four areas does it assess?

Focused Assessment with Sonography in Trauma — bedside ultrasound to detect free fluid (blood). Views: pericardial (subxiphoid), right upper quadrant (Morison's pouch), left upper quadrant (splenorenal), and pelvis (pouch of Douglas). 'eFAST' adds lung views for pneumo/haemothorax.

Give three common interventional radiology procedures used in surgical patients.

Angioembolisation (e.g. for GI bleeding, trauma, or post-partum haemorrhage); percutaneous drainage of abscesses/collections; biliary or nephrostomy drainage; vascular stenting/angioplasty; IVC filter insertion; and image-guided biopsy.

What are the radiation-safety principles 'ALARP' and the three protective measures?

ALARP = As Low As Reasonably Practicable. The three core protective measures are: minimise Time of exposure, maximise Distance from the source (intensity follows the inverse-square law $I \propto \frac{1}{d^{2}}$), and use Shielding (lead aprons/screens). Justification, optimisation and dose limitation underpin IR(ME)R.