Principles of Surgery & Wound Healing Flashcards

Which organism is the most common cause of wound infection in colorectal surgery?

Answer: Bacteroides fragilis

Bacteroides fragilis is the most common organism isolated in post-operative wound infections following colorectal surgery. It is a Gram-negative anaerobe from the colonic flora. Broad-spectrum prophylaxis (e.g., metronidazole plus cephalosporin) covers both aerobic and anaerobic bowel flora.

In a patient with a large ventral hernia, which mesh position has the lowest recurrence rate?

Answer: Retromuscular (Rives-Stoppa: posterior to rectus muscle, preperitoneal)

The retromuscular (Rives-Stoppa) technique, placing mesh posterior to the rectus muscle in the retromuscular plane, achieves the lowest recurrence rates for complex ventral hernias. The mesh is held in place by intra-abdominal pressure and avoids direct bowel contact, reducing adhesion risk.

What is the Principles of ERAS (Enhanced Recovery After Surgery) protocol aimed at?

Answer: Reducing the physiological stress of surgery by perioperative optimisation to accelerate return of function

ERAS (Enhanced Recovery After Surgery) protocols use multimodal evidence-based perioperative care pathways — including preoperative carbohydrate loading, minimal bowel prep, regional anaesthesia, early mobilisation, early oral intake, and avoidance of drains/NG tubes — to reduce the metabolic stress response and accelerate recovery.

A patient post-thyroidectomy develops perioral tingling and muscle cramps. Which complication has occurred?

Answer: Hypocalcaemia from hypoparathyroidism

Post-thyroidectomy hypocalcaemia results from inadvertent removal or devascularisation of the parathyroid glands during surgery, causing hypoparathyroidism. Symptoms include perioral and digital tingling (paraesthesiae), carpopedal spasm (Trousseau's sign), Chvostek's sign, and eventually tetany or seizures.

Which type of wound closure is most appropriate for a severely contaminated wound from a perforated bowel?

Answer: Delayed primary closure (closure at 4–5 days if no infection)

Contaminated or dirty wounds (e.g., from perforated bowel, faecal contamination) should not be closed primarily due to the high risk of wound infection and dehiscence. Delayed primary closure (at 4–5 days) allows the wound to be cleaned and monitored before closure when infection risk has reduced.

What does the term 'physiological dead space' mean in relation to ventilation?

Answer: The total volume of ventilated lung that does not participate in gas exchange, including alveoli with no perfusion

Physiological dead space (Bohr dead space) is the total volume of ventilated lung not involved in gas exchange — it includes anatomical dead space (airways) and alveolar dead space (alveoli ventilated but not perfused). Physiological dead space is increased in pulmonary embolism, ARDS, and emphysema.