General Surgery Principles Practice Questions

Q: What is the concentration of sodium (in mEq/L) in normal saline?

154. Normal Saline (0.9% NaCl) is a crystalloid solution widely used for fluid resuscitation and maintenance. The concentration of 0.9% means there are 9 grams of Sodium Chloride per liter of water. ### **Why 154 is Correct** To calculate the milliequivalents (mEq) of Sodium ($Na^+$) in Normal Saline: 1. The molecular weight of NaCl is approximately 58.5 g/mol. 2. In 1 liter of 0.9% NaCl, there are 9,000 mg of NaCl. 3. $9,000 \text{ mg} / 58.5 \approx 154 \text{ mEq/L}$. Since NaCl dissociates into equal parts $Na^+$ and $Cl^-$, Normal Saline contains **154 mEq/L of Sodium** and **154 mEq/L of Chloride**. ### **Analysis of Incorrect Options** * **A (77 mEq/L):** This is the sodium concentration of **Half-Normal Saline (0.45% NaCl)**. * **B (109 mEq/L):** This is the chloride concentration in **Ringer’s Lactate**. * **C (130 mEq/L):** This is the sodium concentration in **Ringer’s Lactate** (Hartmann’s Solution), which is more physiological than Normal Saline. ### **High-Yield Clinical Pearls for NEET-PG** * **Osmolarity:** Normal Saline has an osmolarity of **308 mOsm/L**, making it slightly hypertonic compared to plasma (285–295 mOsm/L). * **Hyperchloremic Metabolic Acidosis:** Large volumes of Normal Saline can lead to this condition due to the high chloride content (154 mEq/L vs. plasma 100 mEq/L). * **Fluid of Choice:** It is the preferred fluid for resuscitation in patients with **hypochloremic hypokalemic metabolic alkalosis** (e.g., Gastric Outlet Obstruction/Pyloric Stenosis) and for traumatic brain injury to maintain cerebral perfusion pressure.

Q: Which of the following is a correct statement regarding the treatment of burns?

No bandage is required for burns on the head and neck.. **Explanation:** **1. Why Option A is Correct:** Burns on the head and neck are typically managed using the **Exposure (Open) Method**. This is because the face has an excellent blood supply, which promotes rapid healing and helps resist infection. Furthermore, bandages on the face are difficult to secure, can obstruct the airway, and may trap secretions near the eyes, nose, and mouth, increasing the risk of maceration and infection. **2. Analysis of Incorrect Options:** * **Option B:** Immediate application of **ice-cold water** is contraindicated as it causes intense vasoconstriction, which can deepen the burn injury (progression of the zone of stasis to the zone of coagulation) and potentially lead to systemic hypothermia. Room temperature or cool running water (approx. 15°C) is preferred. * **Option C:** Superficial burns (First-degree) are painful due to exposed nerve endings. While they may not require complex debridement, a **soothing dressing** or topical ointment is often applied to reduce pain and protect the regenerating epidermis. * **Option D:** Escharotomy is indicated for **circumferential** (not circumscribed) full-thickness burns. Circumferential burns of the limbs or thorax can cause compartment syndrome or restrict chest expansion, necessitating an incision through the eschar to restore circulation or ventilation. **Clinical Pearls for NEET-PG:** * **Parkland Formula:** $4 \text{ ml} \times \text{Body Weight (kg)} \times \% \text{ TBSA}$. Give half in the first 8 hours. * **Rule of 9s:** Most common method for TBSA estimation; remember the **Lund and Browder chart** is the most accurate for pediatrics. * **Silver Sulfadiazine:** The most common topical agent, but contraindicated in patients with sulfa allergies or on the face (causes staining). * **Mafenide Acetate:** Can penetrate thick eschar but may cause metabolic acidosis (carbonic anhydrase inhibition).

Q: Which of the following is true of eventration of diaphragm?

Early surgery is the treatment. **Explanation:** **Eventration of the diaphragm** is a condition where the diaphragmatic muscle is replaced by thin, fibroelastic tissue, causing the diaphragm to be permanently elevated. **Why Option B is Correct:** Early surgical intervention (Diaphragmatic Plication) is the treatment of choice, especially in symptomatic patients or infants. Plication flattens the diaphragm, stabilizes the mediastinum, and allows the ipsilateral lung to expand, thereby improving ventilation-perfusion mismatch and respiratory mechanics. **Analysis of Incorrect Options:** * **Option A:** It is not a developmental "defect" (like a hole in CDH); rather, it is a **failure of muscularization**. It can be congenital (due to abnormal migration of myoblasts) or acquired (due to phrenic nerve injury). * **Option C:** The defect is **not muscular**. In eventration, the normal striated muscle is replaced by a thin, translucent **aponeurotic/fibrous sheet**. This distinguishes it from a hernia, where there is an actual breach in continuity. * **Option D:** It is **rarely diagnosed clinically**. Most cases are asymptomatic and discovered incidentally on a **Chest X-ray** (showing a smooth, elevated dome of the diaphragm). Definitive diagnosis often requires fluoroscopy (Sniff test) to observe paradoxical or diminished movement. **High-Yield Pearls for NEET-PG:** * **Sniff Test (Fluoroscopy):** The gold standard for assessing diaphragmatic motion. In eventration, the affected side shows paradoxical upward movement during inspiration. * **Most Common Site:** Usually involves the **left** side (unlike traumatic ruptures which also favor the left). * **Differential Diagnosis:** Must be differentiated from **Congenital Diaphragmatic Hernia (CDH)**. In eventration, the pleural and peritoneal sacs remain intact and separated by the fibrous sheet.

Q: What is the most important prognostic factor in melanoma?

Lymph node metastasis. **Explanation:** In the management of cutaneous melanoma, the presence of **Lymph node metastasis** is the single most important prognostic factor for overall survival. Once the disease spreads to the regional lymph nodes (Stage III), the 5-year survival rate drops significantly compared to localized disease, regardless of the primary tumor's characteristics. **Analysis of Options:** * **Lymph node metastasis (Correct):** This is the strongest predictor of survival. The status of the sentinel lymph node is the most important prognostic factor in patients with localized melanoma (Stage I and II) to determine their progression to Stage III. * **Breslow thickness (Incorrect):** While this is the most important prognostic factor for **localized** (Stage I and II) melanoma and determines the T-staging and excision margins, it is superseded by nodal status once metastasis occurs. * **Ulceration (Incorrect):** This is the second most important factor in T-staging after thickness. Its presence upgrades the stage (e.g., from T1a to T1b) and correlates with a worse prognosis, but it is not as significant as nodal involvement. * **Mitotic index (Incorrect):** Though an indicator of tumor proliferation and aggressive behavior, it is no longer the primary determinant for staging in the AJCC 8th edition, though it remains a secondary prognostic feature. **High-Yield Clinical Pearls for NEET-PG:** * **Breslow Thickness:** Measured from the granular layer of the epidermis to the deepest point of invasion (in mm). * **Clark Level:** Based on anatomical layers (obsolete for staging but still occasionally tested). * **Most common site:** Skin (Back in men, Legs in women). * **Most common subtype:** Superficial spreading melanoma. * **Most aggressive subtype:** Nodular melanoma. * **Sentinel Lymph Node Biopsy (SLNB):** Indicated for tumors >1 mm thick or >0.8 mm with ulceration.

Q: Chronic lymphoedema of a limb is predisposed to all of the following except?

Marjolin's ulcer. ### Explanation **Correct Answer: C. Marjolin's ulcer** **Why Marjolin’s Ulcer is the Correct Answer:** A **Marjolin’s ulcer** is a squamous cell carcinoma (SCC) that arises in areas of **chronic scarring, non-healing wounds, or burn scars**. While chronic lymphoedema involves chronic skin changes, it is not typically associated with the specific cicatrization (scarring) process that leads to a Marjolin’s ulcer. Therefore, it is the "except" in this list. **Analysis of Other Options:** * **A. Thickening of the skin:** Chronic lymphostasis leads to the accumulation of protein-rich fluid, which stimulates fibroblast proliferation. This results in **hyperkeratosis and brawny induration** (non-pitting edema), often progressing to *elephantiasis*. * **B. Recurrent soft tissue infections:** Lymphoedema impairs local immune surveillance. The protein-rich stagnant fluid acts as an excellent culture medium for bacteria, leading to frequent episodes of **cellulitis and lymphangitis** (often caused by *Streptococcus*). * **D. Sarcoma:** A dreaded complication of long-standing chronic lymphoedema is **Stewart-Treves Syndrome**, which is an **angiosarcoma** arising in the affected limb (most classically seen after radical mastectomy). **High-Yield NEET-PG Pearls:** * **Stewart-Treves Syndrome:** Usually occurs 10–15 years after a radical mastectomy. It presents as purple-red nodules on the skin. * **Stemmer’s Sign:** Inability to pinch a fold of skin at the base of the second toe; a pathognomonic clinical sign of lymphoedema. * **Marjolin’s Ulcer Key Fact:** It is most commonly a **well-differentiated Squamous Cell Carcinoma** and is known for being more aggressive than standard SCC. * **Investigation of Choice:** Lymphoscintigraphy is the gold standard for diagnosing the cause of lymphoedema.

Q: What is a potential complication of using an airotor at 30,000 rpm for an impacted molar?

Emphysema. **Explanation:** The correct answer is **Emphysema (D)**. **Why it is correct:** An airotor is a high-speed, air-driven drill. When used for surgical procedures like extracting an impacted molar, the high-pressure air used to drive the turbine can escape into the surrounding soft tissue planes. If the air enters the fascial spaces (such as the submandibular, parapharyngeal, or retropharyngeal spaces), it results in **Surgical Emphysema**. Clinically, this presents as sudden swelling and characteristic **crepitus** (a crackling sensation) on palpation. In severe cases, this air can track down into the mediastinum, leading to life-threatening pneumomediastinum. **Why the other options are incorrect:** * **A & C (Necrosis of bone/tissue):** While high-speed drilling generates significant heat that *could* cause thermal necrosis, modern airotors use water-cooling systems to prevent this. Necrosis is a chronic or delayed complication, whereas emphysema is a specific, acute risk associated with the air-pressure mechanism of the drill. * **B (Tissue laceration):** While a slip of the bur can cause a laceration, this is a mechanical error rather than a specific complication of the 30,000 rpm air-driven mechanism itself. **NEET-PG High-Yield Pearls:** * **Prevention:** To avoid emphysema, surgeons prefer using **physiodispensers** (electric motors) rather than air-driven motors for bone guttering. * **Diagnosis:** The hallmark sign of surgical emphysema is **crepitus**. * **Management:** Most cases are mild and managed conservatively with antibiotics (to prevent secondary infection from oral flora) and observation. However, always monitor for respiratory distress. * **Radiology:** On X-ray, it appears as radiolucent streaks of air within soft tissue shadows.

Question 1

What is the concentration of sodium (in mEq/L) in normal saline?

Accepted Answer

154

Answer

77

Answer

109

Answer

130

Question 2

Which of the following is a correct statement regarding the treatment of burns?

Accepted Answer

No bandage is required for burns on the head and neck.

Answer

Immediate application of ice cold water is recommended.

Answer

Superficial burns without blisters do not require dressing.

Answer

Escharotomy is indicated for peripheral circumscribed lesions.

Question 3

What is the treatment of choice for a patient with a maxillary complete denture experiencing severe bilateral tuberosity undercuts?

Accepted Answer

Remove the tissue on only one side if possible

Answer

Remove both tuberosity undercuts

Answer

Maintain the undercuts as they help in retention

Answer

Use a mucostatic impression material

Question 4

Which of the following is true of eventration of diaphragm?

Accepted Answer

Early surgery is the treatment

Answer

It is a developmental defect

Answer

The defect is usually muscular

Answer

It is diagnosed mostly clinically

Question 5

Which of the following is true about chylothorax?

Accepted Answer

The treatment of choice is excision and ligation of the thoracic duct.

Answer

It is more common on the left side.

Answer

The fluid is clear.

Answer

Immediate thoracotomy should be performed.

Question 6

What is the most important prognostic factor in melanoma?

Accepted Answer

Lymph node metastasis

Answer

Breslow thickness

Answer

Mitotic index

Answer

Ulceration

Question 7

Smaller straight elevators work on which principle?

Accepted Answer

Lever principle.

Answer

Wedge principle.

Answer

Both.

Answer

Any of the above.

Question 8

A chest physician performs bronchoscopy in the procedure room of the outpatient department. To make the instrument safe for use in the next patient, what is the most appropriate method of disinfection?

Accepted Answer

2% glutaraldehyde for 20 minutes

Answer

70% alcohol for 5 minutes

Answer

2% formaldehyde for 10 minutes

Answer

1% sodium hypochlorite for 15 minutes

Question 9

Chronic lymphoedema of a limb is predisposed to all of the following except?

Accepted Answer

Marjolin's ulcer

Answer

Thickening of the skin

Answer

Recurrent soft tissue infections

Answer

Sarcoma

Question 10

What is a potential complication of using an airotor at 30,000 rpm for an impacted molar?

Accepted Answer

Emphysema

Answer

Necrosis of bone

Answer

Tissue laceration

Answer

Tissue necrosis

General Surgery Principles — MCQs

General Surgery Principles — MCQs

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