General Surgery Principles — MCQs

General Surgery Principles Indian Medical PG Practice Questions and MCQs

Question 661: What is the concentration of sodium (in mEq/L) in normal saline?

A. 77
B. 109
C. 130
D. 154 (Correct Answer)

Explanation: 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.

Question 662: What is the treatment of choice for a patient with a maxillary complete denture experiencing severe bilateral tuberosity undercuts?

A. Remove both tuberosity undercuts
B. Remove the tissue on only one side if possible (Correct Answer)
C. Maintain the undercuts as they help in retention
D. Use a mucostatic impression material

Explanation: ### Explanation **Concept:** In pre-prosthetic surgery, the primary goal is to create a stable, retentive base for a prosthesis. Maxillary tuberosity undercuts are common; while small undercuts can aid in retention, **severe bilateral undercuts** create a mechanical interference. If a denture is fabricated over bilateral undercuts, it cannot be seated without traumatizing the mucosa or requiring excessive relief of the denture base, which compromises the peripheral seal. **Why Option B is Correct:** The standard surgical principle is to **unilaterally reduce** the undercut. By removing the bony or soft tissue interference on only one side, the clinician creates a "path of insertion." The denture can be angled into the remaining undercut on one side and then seated over the reduced side. This approach preserves as much anatomy as possible for lateral stability while ensuring the denture can be physically placed. **Analysis of Incorrect Options:** * **Option A:** Removing both undercuts is generally unnecessary and aggressive. It reduces the surface area available for lateral stability and may lead to a flatter ridge. * **Option C:** While mild undercuts help retention, *severe* bilateral undercuts make it physically impossible to seat a rigid denture base. * **Option D:** Mucostatic materials (like plaster) record tissues at rest but do not solve the mechanical problem of a bony interference during the insertion of a hard acrylic base. **Clinical Pearls for NEET-PG:** * **Path of Insertion:** Always look for the most conservative surgical intervention that allows for a functional path of insertion. * **Maxillary vs. Mandibular:** Maxillary undercuts are more common in the tuberosity region, whereas mandibular undercuts are often found in the retromylohyoid or labial mental regions. * **Radiographic Assessment:** Before surgery, a panoramic radiograph or CT is essential to rule out a low-lying maxillary sinus (pneumatization) to avoid accidental oroantral communication during tuberosity reduction.

Question 663: Which of the following is a correct statement regarding the treatment of burns?

A. No bandage is required for burns on the head and neck. (Correct Answer)
B. Immediate application of ice cold water is recommended.
C. Superficial burns without blisters do not require dressing.
D. Escharotomy is indicated for peripheral circumscribed lesions.

Explanation: **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).

Question 664: Which of the following is true of eventration of diaphragm?

A. It is a developmental defect
B. Early surgery is the treatment (Correct Answer)
C. The defect is usually muscular
D. It is diagnosed mostly clinically

Explanation: **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.

Question 665: Which of the following is true about chylothorax?

A. It is more common on the left side.
B. The fluid is clear.
C. Immediate thoracotomy should be performed.
D. The treatment of choice is excision and ligation of the thoracic duct. (Correct Answer)

Explanation: **Explanation** **Chylothorax** is the accumulation of chyle (lymphatic fluid) in the pleural space, most commonly due to trauma or malignancy (lymphoma) causing disruption of the thoracic duct. **Why Option D is Correct:** The definitive surgical treatment for persistent or high-output chylothorax is the **ligation of the thoracic duct**. This is typically performed just above the diaphragm (at the level of T8-T12) via a right-sided approach (thoracoscopy or thoracotomy), regardless of the side of the effusion. This prevents further leakage into the pleural space. **Why Other Options are Incorrect:** * **Option A:** It is more common on the **right side**. The thoracic duct enters the thorax through the aortic hiatus and ascends on the right side of the vertebral column before crossing to the left at the level of the T4-T5 vertebrae. * **Option B:** The fluid is **milky white**, not clear. It is rich in chylomicrons and triglycerides (typically >110 mg/dL), which gives it an opalescent appearance. * **Option C:** Immediate surgery is rarely indicated. Initial management is **conservative**, including intercostal drainage and dietary modification (NPO or a diet rich in **Medium Chain Triglycerides (MCT)**, which bypass the lymphatic system). Surgery is reserved for cases where conservative management fails (e.g., leak >1 liter/day for 5 days). **Clinical Pearls for NEET-PG:** * **Diagnostic Test:** Presence of **chylomicrons** on lipoprotein electrophoresis is the gold standard. * **Anatomy:** The thoracic duct originates from the **Cisterna Chyli** (L2 level). * **MCT Diet:** Long-chain triglycerides are absorbed into lymphatics; MCTs are absorbed directly into the portal vein, reducing chyle flow.

Question 666: What is the most important prognostic factor in melanoma?

A. Breslow thickness
B. Mitotic index
C. Ulceration
D. Lymph node metastasis (Correct Answer)

Explanation: **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.

Question 667: Smaller straight elevators work on which principle?

A. Wedge principle.
B. Lever principle. (Correct Answer)
C. Both.
D. Any of the above.

Explanation: In dental and general surgery, elevators are instruments designed to luxate teeth or displace fragments. The mechanical function of a straight elevator depends primarily on its size and how it is applied to the target. **Explanation of the Correct Answer:** **Option B (Lever Principle)** is the correct answer for **smaller straight elevators**. These instruments function as **Class I Levers**, where the fulcrum (the alveolar bone crest) lies between the effort (the surgeon’s hand) and the resistance (the tooth or fragment). Smaller elevators are specifically designed to be inserted into the periodontal space to lift the tooth coronally. By applying a downward force on the handle, the working tip exerts an upward force, displacing the object based on the lever law. **Explanation of Incorrect Options:** * **Option A (Wedge Principle):** While large straight elevators or "Coupland" elevators can act as wedges when driven vertically into the PDL space to expand bone, the primary mechanical advantage of a *smaller* straight elevator is its use as a lever. The wedge principle is more characteristic of apical fragment ejectors or when an elevator is used to split a root. * **Option C & D:** These are incorrect because, in the context of standard surgical physics for NEET-PG, the distinction is made based on the primary intended movement. Smaller elevators lack the bulk to act effectively as a wedge without risking fracture; thus, they are used almost exclusively as levers. **High-Yield Clinical Pearls for NEET-PG:** * **Three Principles of Elevators:** 1. Lever Principle (most common), 2. Wedge Principle, 3. Wheel and Axle Principle (specifically for **Cross-bar/Winter’s elevators**). * **Fulcrum Warning:** Never use an adjacent tooth as a fulcrum unless it is also slated for extraction; the alveolar bone should always be the fulcrum. * **Straight Elevator (Coupland):** The most commonly used elevator for luxation before forceps application.

Question 668: 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?

A. 70% alcohol for 5 minutes
B. 2% glutaraldehyde for 20 minutes (Correct Answer)
C. 2% formaldehyde for 10 minutes
D. 1% sodium hypochlorite for 15 minutes

Explanation: **Explanation:** The core concept here is the **Spaulding Classification** of medical devices. A bronchoscope is classified as a **semi-critical item** because it comes into contact with mucous membranes or non-intact skin but does not penetrate sterile tissues. Such instruments require **High-Level Disinfection (HLD)**. **Why Option B is correct:** **2% Glutaraldehyde (Cidex)** is the gold standard for HLD of heat-sensitive flexible endoscopes (like bronchoscopes and gastrointestinal scopes). It is a dialdehyde that acts by alkylation of proteins and nucleic acids. A contact time of **20 minutes** at room temperature is sufficient to kill all vegetative bacteria, fungi, viruses, and mycobacteria. (Note: To achieve full sterilization, i.e., killing spores, an immersion time of 10 hours is required). **Why the other options are incorrect:** * **70% Alcohol (Option A):** This is a low-to-intermediate level disinfectant. It is unsuitable for bronchoscopes because it lacks sporicidal activity and can damage the luer-locks and adhesives of flexible scopes. * **2% Formaldehyde (Option C):** While a potent disinfectant, it is rarely used for instruments due to its pungent odor, slow action, and known **carcinogenic** potential. * **1% Sodium Hypochlorite (Option D):** This is primarily used for surface disinfection and managing blood spills. It is highly **corrosive** to the metal components and delicate optics of flexible endoscopes. **High-Yield Clinical Pearls for NEET-PG:** * **Sterilization vs. Disinfection:** Glutaraldehyde is a "Chemosterilant"—it disinfects in 20 mins but sterilizes in 10 hours. * **Ortho-phthalaldehyde (OPA):** A newer alternative to glutaraldehyde that is faster (12 mins) and doesn't require activation, though it is more expensive. * **Prions:** Standard glutaraldehyde does *not* inactivate prions; sodium hypochlorite or autoclaving at 134°C is required. * **Shelf life:** Once activated, 2% glutaraldehyde is generally effective for **14 days**.

Question 669: Chronic lymphoedema of a limb is predisposed to all of the following except?

A. Thickening of the skin
B. Recurrent soft tissue infections
C. Marjolin's ulcer (Correct Answer)
D. Sarcoma

Explanation: ### 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.

Question 670: What is a potential complication of using an airotor at 30,000 rpm for an impacted molar?

A. Necrosis of bone
B. Tissue laceration
C. Tissue necrosis
D. Emphysema (Correct Answer)

Explanation: **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.

Practice by Chapter

Wound Healing and Care

Practice Questions

Surgical Infections

Practice Questions

Fluid and Electrolyte Management

Practice Questions

Nutrition in Surgical Patients

Practice Questions

Hemostasis and Blood Transfusion

Practice Questions

Surgical Instruments and Equipment

Practice Questions

Sutures and Stapling Devices

Practice Questions

Minimal Access Surgery Principles

Practice Questions

Surgical Complications

Practice Questions

Anesthesia Principles for Surgeons

Practice Questions

Surgical Oncology Principles

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Evidence-Based Surgery

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