General Surgery Principles Practice Questions

Q: In an adult patient with pleural effusion, what is the most appropriate site for thoracentesis?

7th intercostal space in the midaxillary line. ### Explanation **Correct Answer: B. 7th intercostal space in the midaxillary line** Thoracentesis (pleural tap) is performed to remove fluid from the pleural space. The goal is to select a site that is low enough to access gravity-dependent fluid but high enough to avoid injury to the diaphragm and abdominal viscera (liver/spleen). The **7th to 9th intercostal spaces** between the **midaxillary line and the posterior axillary line** are the preferred sites. At the midaxillary line, the 7th intercostal space provides a safe window above the diaphragmatic reflection while ensuring the needle enters the widest part of the costodiaphragmatic recess. **Analysis of Incorrect Options:** * **Option A (5th ICS, Midclavicular line):** This site is too high for efficient fluid drainage and carries a risk of injuring the heart (on the left) or the lung parenchyma. * **Option C (2nd ICS, Midclavicular line):** This is the classic site for **needle decompression of a tension pneumothorax**, not for pleural effusion. * **Option D (10th ICS):** This is too low. The diaphragm typically rises to the level of the 8th–10th ribs posteriorly during expiration; inserting a needle here poses a high risk of penetrating the diaphragm and causing intra-abdominal injury (liver or spleen laceration). **NEET-PG High-Yield Pearls:** * **The "Safe Zone":** Always insert the needle **immediately above the rib (superior border)** to avoid the neurovascular bundle (Intercostal vein, artery, and nerve), which runs in the costal groove at the inferior border of the rib. * **Positioning:** The patient should ideally be sitting upright, leaning forward. * **Fluid Limit:** To avoid re-expansion pulmonary edema, do not remove more than **1,000–1,500 mL** of fluid in a single session. * **Gold Standard:** Ultrasound-guided thoracentesis is now preferred over the "blind" clinical approach to minimize complications like pneumothorax.

Q: Which of the following muscles is not incised during a posterolateral thoracotomy?

Pectoralis major. **Explanation:** The **posterolateral thoracotomy** is the most common surgical approach for major lung resections (lobectomy/pneumonectomy) and esophageal surgeries. The incision typically begins midway between the spine and the scapula, curves around the scapular tip, and follows the line of the rib (usually the 5th intercostal space) toward the anterior axillary line. **Why Pectoralis Major is the correct answer:** The **Pectoralis major** is an anterior chest wall muscle. Its origin is on the clavicle, sternum, and upper ribs, and it inserts into the humerus. Since the posterolateral incision stays posterior to the anterior axillary line, the pectoralis major is never encountered or incised. **Analysis of incorrect options:** * **Latissimus dorsi:** This is the largest muscle of the back and the first major muscle layer encountered. It must be divided (incised) to gain access to the deeper structures. * **Serratus anterior:** Located on the lateral chest wall, its posterior fibers are often divided or retracted during this procedure to expose the ribs. * **Intercostals:** To enter the pleural cavity, the intercostal muscles (external, internal, and innermost) in the specific intercostal space must be incised. **High-Yield Clinical Pearls for NEET-PG:** * **Muscle-Sparing Thoracotomy:** Modern variations aim to retract rather than divide the latissimus dorsi and serratus anterior to reduce post-operative pain. * **Nerve at Risk:** The **Long Thoracic Nerve** (supplying serratus anterior) and the **Thoracodorsal Nerve** (supplying latissimus dorsi) are at risk if the dissection is too extensive. * **Anterior Thoracotomy:** This is the approach where the Pectoralis major *would* be incised (used for trauma or cardiac access).

Q: What is the preservative used for this suture material?

isopropyl alcohol. ***Isopropyl alcohol*** - **Catgut sutures** are preserved in **isopropyl alcohol** to maintain their sterility and prevent bacterial contamination during storage. - **Isopropyl alcohol (70%)** provides effective antimicrobial action while maintaining the **tensile strength** and flexibility of the catgut material. *Saline* - **Saline** lacks antimicrobial properties and would not provide adequate preservation for long-term storage of suture materials. - Storage in saline could lead to **bacterial growth** and **degradation** of the catgut suture material over time. *Ethanol* - **Ethanol** can cause excessive dehydration and **hardening** of catgut sutures, making them brittle and difficult to handle. - Unlike **isopropyl alcohol**, ethanol may compromise the **flexibility** and handling characteristics of the suture material. *Formalin* - **Formalin** is a tissue fixative used for histopathological specimens, not for preserving surgical suture materials. - Formalin would cause **cross-linking** and **hardening** of the catgut protein, making it unsuitable for surgical use.

Q: In a patient with lung cancer, which of the following is a contraindication for surgical resection?

Malignant pleural effusion. ### Explanation In the management of Non-Small Cell Lung Cancer (NSCLC), determining resectability is crucial. The presence of a **Malignant Pleural Effusion (Option A)** signifies that the tumor has disseminated within the pleural cavity. According to the TNM staging system (8th edition), this is classified as **M1a (Stage IV)** disease. Surgical resection is generally contraindicated in Stage IV because the disease is systemic rather than localized, and surgery does not offer a survival benefit or curative potential in this setting. **Analysis of Incorrect Options:** * **Hilar Lymphadenopathy (Option B):** This corresponds to N1 nodal involvement. While it indicates a higher stage (Stage II), it is not a contraindication to surgery; these patients typically undergo lobectomy with lymph node dissection. * **Consolidation of one lobe (Option C):** This is often a secondary effect of bronchial obstruction by the tumor (obstructive pneumonitis). As long as the tumor itself is resectable, consolidation limited to the lobe or even the entire lung is not a contraindication. * **Involvement of the visceral pleura (Option D):** This is classified as T2 disease. It indicates local extension but remains localized to the lung structure, making it amenable to surgical resection. **NEET-PG High-Yield Pearls:** * **Absolute Contraindications to Surgery (The "STOP" Criteria):** * **S:** Superior Vena Cava (SVC) Syndrome. * **T:** Tracheal involvement or Carina involvement (less than 2cm from carina). * **O:** Outside metastasis (Distant metastasis, including Malignant Pleural Effusion). * **P:** Paralysis of the Left Vocal Cord (indicates Recurrent Laryngeal Nerve involvement) or Phrenic nerve. * **PFT Criteria:** A predicted post-operative FEV1 of **<800ml** or **<30-40%** of predicted is generally a contraindication to pneumonectomy.

Q: What is the most common tumour of the posterior mediastinum?

Neurogenic tumour. The mediastinum is anatomically divided into compartments, each characterized by specific resident structures and associated pathologies. **Correct Answer: A. Neurogenic tumour** Neurogenic tumours are the most common primary mediastinal tumours overall, and specifically, they account for over **90% of posterior mediastinal masses**. They arise from the intercostal nerves (e.g., Schwannomas, Neurofibromas) or the sympathetic chain (e.g., Ganglioneuromas, Neuroblastomas). Because the paravertebral sulcus is located in the posterior compartment, these nerve-derived tumours are almost exclusively found here. **Explanation of Incorrect Options:** * **B. Thymoma:** This is the most common primary tumour of the **anterior mediastinum**. While it is the most common mediastinal tumour in adults overall, its location is strictly pre-vascular. * **C. Cyst:** Bronchogenic or pericardial cysts are most frequently found in the **middle mediastinum**. While enteric cysts can occur posteriorly, they are far less common than neurogenic tumours. * **D. Lymphoma:** Lymphomas typically present in the **anterior or middle mediastinum** (associated with lymph node chains). They are rarely isolated to the posterior compartment. **High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Anterior Mediastinal Masses (4 Ts):** **T**hymoma, **T**eratoma (Germ cell tumours), **T**errible Lymphoma, and **T**hyroid (Retrosternal goiter). * **Middle Mediastinum:** Predominantly characterized by lymphadenopathy and developmental cysts. * **Posterior Mediastinum:** Think "Nerves." Schwannoma is the most common type in adults. * **Imaging Gold Standard:** Contrast-Enhanced CT (CECT) is the initial investigation of choice, but MRI is superior for evaluating spinal canal involvement in posterior tumours ("Dumbbell tumours").

Q: A 20-year-old female presents to the casualty with right iliac fossa pain, local guarding, and tenderness. Which of the following management interventions should NOT be done?

None of the above. **Explanation:** The clinical presentation of right iliac fossa (RIF) pain, local guarding, and tenderness in a young female is highly suggestive of **Acute Appendicitis** or an acute surgical abdomen. The management of such cases follows the standard surgical principle of "stabilize and prepare for potential surgery." **1. Why "None of the above" is correct:** All the interventions listed (A, B, and C) are standard, appropriate management steps for a patient with a suspected acute abdomen. Therefore, none of them are contraindicated. **2. Analysis of Options:** * **Nil Orally (NPO):** This is the most critical initial step. It prevents aspiration during potential emergency anesthesia and rests the bowel. * **Intravenous Glucose/Fluids:** Since the patient is NPO and may have lost fluids due to vomiting or decreased intake, IV fluids (often Dextrose-Normal Saline) are essential to maintain hydration and electrolyte balance. * **Pethidine (Analgesia):** Historically, there was a myth that analgesics "mask" the signs of peritonitis. Modern surgical teaching (and ATLS guidelines) emphasizes that providing pain relief (like Pethidine or Morphine) does **not** interfere with the diagnosis and is humane. It reduces patient distress and may actually make the physical exam easier by reducing voluntary guarding. **Clinical Pearls for NEET-PG:** * **Analgesia in Acute Abdomen:** Opioids do not mask physical signs or delay diagnosis; they are recommended once a preliminary evaluation is done. * **Pethidine vs. Morphine:** Pethidine was traditionally preferred in biliary colic due to the belief it causes less spasm of the Sphincter of Oddi, though recent evidence suggests little clinical difference. * **Most common cause of RIF pain in young females:** Acute appendicitis, but always rule out ectopic pregnancy (order a UPT) and ovarian torsion.

Q: Silk is which class of suture?

Class 1. **Explanation:** The classification of non-absorbable sutures is defined by the **United States Pharmacopeia (USP)** based on the material's composition and construction. **Why Class 1 is correct:** According to USP standards, **Class 1** sutures are defined as silk or synthetic fibers with a monofilament, twisted, or braided construction. Since Silk is a natural protein fiber produced by the *Bombyx mori* silkworm and is typically braided, it falls strictly into Class 1. **Analysis of incorrect options:** * **Class 2:** This category includes natural or synthetic fibers that are **coated**, or those where the coating contributes to the thickness but not the strength (e.g., cotton, linen, or coated synthetic fibers). * **Class 3:** This category is reserved specifically for **monofilament or multifilament metal wire** (e.g., stainless steel sutures). **High-Yield Clinical Pearls for NEET-PG:** * **Nature of Silk:** Although classified as "non-absorbable," silk is technically **slowly absorbable**. It undergoes progressive degradation via proteolysis and usually disappears from the tissue within 2 years. * **Tissue Reaction:** Silk elicits the **highest tissue reaction** among all non-absorbable sutures because it is a foreign protein. * **Capillarity:** Due to its braided nature, silk exhibits high capillarity (wicking action), which can harbor bacteria; therefore, it is generally avoided in the presence of active infection. * **Common Use:** It is frequently used for securing drains or in mucosal closures where its superior handling and knot security are beneficial.

Q: Which of the following is the most commonly used site for Deep Brain Stimulation to reduce the frequency of Parkinsonism symptoms?

Subthalamic Nucleus. ### Explanation **Deep Brain Stimulation (DBS)** is a neurosurgical procedure involving the implantation of electrodes into specific brain targets to modulate abnormal electrical signals. In the management of Parkinson’s Disease (PD), DBS is indicated for patients with motor fluctuations or tremors that are refractory to medical therapy. **Why Subthalamic Nucleus (STN) is the Correct Answer:** The **Subthalamic Nucleus (STN)** is the most common and preferred target for DBS in Parkinson’s Disease. Stimulating the STN effectively reduces the "off" time and allows for a significant reduction in the dosage of dopaminergic medications (like Levodopa). It is particularly effective for treating bradykinesia, rigidity, and tremors. **Analysis of Incorrect Options:** * **Globus Pallidus (GPi):** The Globus Pallidus Internus is the second most common site. While it is excellent for reducing medication-induced dyskinesias, it does not typically allow for the same degree of medication reduction as STN-DBS. * **Striatus & Putamen:** These structures are part of the basal ganglia circuitry involved in the pathology of PD. However, they are not used as primary targets for DBS because stimulating them does not provide the same therapeutic modulation of the motor circuit as the STN or GPi. **NEET-PG High-Yield Pearls:** * **Target for Essential Tremor:** The **Ventral Intermediate Nucleus (Vim)** of the Thalamus is the preferred DBS target for Essential Tremor and Parkinsonian tremor (though it doesn't help with bradykinesia). * **Target for Dystonia:** The **Globus Pallidus Internus (GPi)** is the primary target. * **Contraindication:** DBS is generally avoided in patients with significant cognitive impairment or untreated depression, as STN-DBS can sometimes worsen neuropsychiatric symptoms. * **Mechanism:** DBS acts like a "functional lesion," inhibiting overactive nuclei in the indirect pathway of the basal ganglia.

Q: Spontaneous pneumothorax exceeding what percentage of the chest cavity should have a chest tube inserted?

25%. **Explanation:** The management of a spontaneous pneumothorax is primarily determined by the size of the collapse and the patient's clinical stability. According to standard surgical guidelines (including British Thoracic Society and ATLS principles), a pneumothorax is generally considered "large" when it exceeds **25%** of the hemithorax volume (or when the distance from the chest wall to the lung margin at the level of the hilum is >2 cm). 1. **Why 25% is correct:** At this threshold, the lung's functional capacity is significantly compromised, and the rate of spontaneous resorption (approx. 1.25% per day) is too slow for conservative management. Insertion of an intercostal drainage (ICD) tube or a pigtail catheter is indicated to facilitate lung re-expansion and prevent progression to tension pneumothorax. 2. **Why other options are incorrect:** * **10%:** Small pneumothoraces (<15-20%) in asymptomatic patients can often be managed with observation and supplemental oxygen, which increases the rate of nitrogen absorption. * **45% and 60%:** These represent massive collapses. While they definitely require a chest tube, the clinical intervention threshold is much lower (at 25%) to prevent respiratory failure. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause:** Rupture of subpleural blebs (usually in tall, thin young males). * **Site of Chest Tube:** 5th intercostal space, anterior to the mid-axillary line (Safe Triangle). * **Tension Pneumothorax:** This is a **clinical diagnosis**. Never wait for an X-ray; perform immediate needle decompression in the 5th ICS (adults) or 2nd ICS (pediatrics). * **Recurrence:** If a second episode occurs, definitive management like pleurodesis or VATS is indicated.

Question 1

In an adult patient with pleural effusion, what is the most appropriate site for thoracentesis?

Accepted Answer

7th intercostal space in the midaxillary line

Answer

5th intercostal space in the midclavicular line

Answer

2nd intercostal space adjacent to the sternum

Answer

10th intercostal space adjacent to the vertebral column

Question 2

From the surgery performed, what is the gold standard investigation used to diagnose this condition?

Accepted Answer

CECT

Answer

Ultrasound

Answer

MRI

Answer

Laparotomy

Question 3

Which of the following muscles is not incised during a posterolateral thoracotomy?

Accepted Answer

Pectoralis major

Answer

Serratus anterior

Answer

Latissimus dorsi

Answer

Intercostals

Question 4

What is the preservative used for this suture material?

Accepted Answer

isopropyl alcohol

Answer

saline

Answer

ethanol

Answer

formalin

Question 5

In a patient with lung cancer, which of the following is a contraindication for surgical resection?

Accepted Answer

Malignant pleural effusion

Answer

Hilar lymphadenopathy

Answer

Consolidation of one lobe

Answer

Involvement of the visceral pleura

Question 6

What is the most common tumour of the posterior mediastinum?

Accepted Answer

Neurogenic tumour

Answer

Thymoma

Answer

Cyst

Answer

Lymphoma

Question 7

A 20-year-old female presents to the casualty with right iliac fossa pain, local guarding, and tenderness. Which of the following management interventions should NOT be done?

Accepted Answer

None of the above

Answer

Intravenous glucose

Answer

Pethidine 100 mg intramuscularly

Answer

Nil orally

Question 8

Silk is which class of suture?

Accepted Answer

Class 1

Answer

Class 2

Answer

Class 3

Answer

None of the above

Question 9

Which of the following is the most commonly used site for Deep Brain Stimulation to reduce the frequency of Parkinsonism symptoms?

Accepted Answer

Subthalamic Nucleus

Answer

Striatus

Answer

Globus Pallidus

Answer

Putamen

Question 10

Spontaneous pneumothorax exceeding what percentage of the chest cavity should have a chest tube inserted?

Accepted Answer

25%

Answer

10%

Answer

45%

Answer

60%

General Surgery Principles — MCQs

General Surgery Principles — MCQs

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