Question 1

All of the following are causes of pneumoperitoneum except?

Accepted Answer

Hirschsprung's disease. **Explanation:**

**Pneumoperitoneum** refers to the presence of free air within the peritoneal cavity, most commonly caused by the perforation of a hollow viscus.

**Why Hirschsprung’s Disease is the correct answer:**
Hirschsprung’s disease is a functional bowel obstruction caused by the absence of ganglion cells in the distal colon. While it leads to massive bowel dilatation (**megacolon**), the bowel wall typically remains intact. Therefore, it presents with **pneumatosis intestinalis** (air within the bowel wall) or massive distension, but not pneumoperitoneum, unless a secondary complication like enterocolitis leads to a perforation (which is rare compared to the primary pathology).

**Analysis of Incorrect Options:**
*   **Perforated Peptic Ulcer:** This is the **most common cause** of spontaneous pneumoperitoneum. Gastric or duodenal contents and air escape into the peritoneal cavity.
*   **Laparoscopic Procedure:** This is a cause of **iatrogenic pneumoperitoneum**. Carbon dioxide (CO2) is intentionally insufflated into the abdomen to create a working space. Residual air can persist for several days post-surgery.
*   **Perforated Appendix:** While less common than peptic ulcers (due to the appendix often being walled off by the omentum), a free perforation of the appendix can release intraluminal gas into the peritoneum.

**NEET-PG High-Yield Pearls:**
*   **Most sensitive sign:** Air under the right diaphragm on an erect X-ray chest (can detect as little as 1–2 ml of air).
*   **Left Lateral Decubitus View:** The preferred position if the patient cannot stand; air is seen over the liver shadow.
*   **Rigler’s Sign:** Seeing both sides of the bowel wall due to free intraperitoneal air.
*   **Football Sign:** A large radiolucency outlining the entire peritoneal cavity in massive pneumoperitoneum (common in neonates). [Practice more Surgery questions on OnCourse]

Question 2

Hyperacute rejection is due to which of the following mechanisms?

Accepted Answer

Preformed antibodies. **Explanation:**

**Hyperacute Rejection** is an immediate, irreversible immunological reaction occurring within minutes to hours after organ transplantation.

**1. Why Option A is Correct:**
The mechanism is a **Type II Hypersensitivity reaction**. It is mediated by **preformed circulating antibodies** (IgG) in the recipient’s blood. These antibodies are directed against donor antigens (typically ABO blood group antigens or HLA Class I antigens). Upon reperfusion, these antibodies bind to the donor vascular endothelium, activating the **complement system**. This leads to rapid endothelial damage, platelet aggregation, and diffuse intravascular thrombosis, resulting in the "blue graft" appearance and graft necrosis.

**2. Why Other Options are Incorrect:**
*   **Option B:** Cytotoxic T lymphocyte (CD8+) mediated injury is the hallmark of **Acute Cellular Rejection**, which typically occurs days to weeks after transplant.
*   **Option C:** Endothelitis (inflammation of the vessel wall) is a feature of **Acute Antibody-Mediated Rejection**, but it is caused by *recipient* antibodies against donor tissue, not donor antibodies.
*   **Option D:** Macrophages play a role in chronic inflammation and delayed-type hypersensitivity but are not the primary mediators of the rapid vascular collapse seen in hyperacute rejection.

**3. High-Yield Clinical Pearls for NEET-PG:**
*   **Prevention:** Hyperacute rejection is prevented by **Cross-matching** (mixing recipient serum with donor lymphocytes) and ABO compatibility testing.
*   **Treatment:** There is no effective treatment once it starts; the graft must be **surgically removed**.
*   **Risk Factors:** Previous blood transfusions, multiple pregnancies, or prior organ transplants (all of which sensitize the recipient).
*   **Pathology:** Characterized by **Fibrinoid necrosis** of capillaries and "starry sky" appearance due to neutrophilic infiltration. [Practice more Surgery questions on OnCourse]

Question 3

Bochdalek hernia occurs through which anatomical structure?

Accepted Answer

Diaphragm. **Explanation:**

**Bochdalek hernia** is the most common type of **Congenital Diaphragmatic Hernia (CDH)**, accounting for approximately 85-90% of cases. It occurs due to the failure of the **pleuroperitoneal membrane** to fuse with the septum transversum and dorsal mesentery of the esophagus during embryonic development (usually between the 8th and 10th week). This results in a posterolateral defect in the **diaphragm**, most commonly on the **left side** (80-85%), allowing abdominal viscera to herniate into the thoracic cavity.

**Analysis of Incorrect Options:**
*   **B. Lumbar triangle:** Hernias through the superior lumbar triangle (Grynfeltt-Lesshaft) or inferior lumbar triangle (Petit) are types of lumbar hernias, not diaphragmatic.
*   **C. Femoral region:** This is the site for femoral hernias, which occur through the femoral canal, medial to the femoral vein.
*   **D. Obturator canal:** This is the site for obturator hernias, which typically present with the Howship-Romberg sign (pain in the medial thigh).

**High-Yield Clinical Pearls for NEET-PG:**
*   **Mnemonic:** **B**ochdalek is **B**ack and **B**ad (Posterolateral, associated with severe pulmonary hypoplasia). **M**orgagni is **M**edial/Anterior.
*   **Clinical Triad:** Scaphoid abdomen, respiratory distress, and shifted heart sounds.
*   **Radiology:** Chest X-ray shows air-filled bowel loops in the hemithorax and a mediastinal shift.
*   **Management:** Initial stabilization involves **intubation** (avoid bag-mask ventilation to prevent bowel distension) and **nasogastric suction**. Surgery is not an emergency; it is performed after stabilizing pulmonary hypertension. [Practice more Surgery questions on OnCourse]

Question 4

A 37-year-old woman presents with high fever (39.5°C), nausea, and vomiting. Physical examination reveals increased abdominal pain in the paraumbilical region, rebound tenderness over McBurney's point, and a positive psoas sign. Blood tests show marked leukocytosis. What is the most likely diagnosis?

Accepted Answer

Appendicitis. ### Explanation

**Correct Answer: B. Appendicitis**

The clinical presentation is a classic textbook case of **Acute Appendicitis**. The diagnosis is primarily clinical, based on the following findings:
*   **Paraumbilical pain:** This represents visceral pain from the T10 dermatome as the appendix distends.
*   **McBurney’s Point Tenderness:** As the parietal peritoneum becomes inflamed, the pain localizes to the Right Iliac Fossa (RIF).
*   **Psoas Sign:** Pain on extension of the right hip indicates an inflamed appendix in a **retrocecal** position, irritating the iliopsoas muscle.
*   **Systemic Signs:** High fever, nausea, vomiting, and marked leukocytosis (left shift) are indicative of an acute inflammatory/infectious process.

**Why Incorrect Options are Wrong:**
*   **A. Ectopic Pregnancy:** While it causes RIF pain, it is usually associated with amenorrhea, vaginal bleeding, and hemodynamic instability if ruptured. Fever and high leukocytosis are less common unless there is secondary infection.
*   **C. Cholecystitis:** Pain is typically localized in the **Right Upper Quadrant (RUQ)** and radiates to the right scapula (Boas' sign). Murphy’s sign would be positive, not McBurney’s.
*   **D. Nephrolithiasis:** Presents as "loin to groin" colicky pain. While it causes nausea, it rarely presents with high fever or rebound tenderness unless complicated by pyelonephritis.

**High-Yield Clinical Pearls for NEET-PG:**
*   **Alvarado Score (MANTRELS):** A score ≥7 is highly suggestive of appendicitis.
*   **Most common position:** Retrocecal (75%), followed by Pelvic (20%).
*   **Rovsing’s Sign:** Pain in the RIF when the Left Iliac Fossa is palpated.
*   **Investigation of Choice:** Contrast-Enhanced CT (CECT) is the gold standard in adults; Ultrasound is preferred in children and pregnant women. [Practice more Surgery questions on OnCourse]

Question 5

Splenectomy is done to tide over the acute crises of uncontrollable:

Accepted Answer

ITP. **Explanation:**

**1. Why ITP is the Correct Answer:**
Immune Thrombocytopenic Purpura (ITP) is an autoimmune condition where IgG autoantibodies coat platelets, leading to their premature destruction by splenic macrophages. In **acute, life-threatening crises** (such as intracranial or gastrointestinal hemorrhage) where medical management (steroids, IVIG, or platelet transfusions) fails to stabilize the patient, an **emergency splenectomy** is performed. Removing the spleen eliminates both the primary site of platelet destruction and a major source of autoantibody production, leading to a rapid rise in platelet counts.

**2. Why Other Options are Incorrect:**
*   **TTP (Thrombotic Thrombocytopenic Purpura):** The pathophysiology involves a deficiency of the ADAMTS13 enzyme, leading to microthrombi. The primary treatment is **Plasmapheresis (Plasma Exchange)**. Splenectomy is not indicated for acute crises and is rarely considered even in refractory cases.
*   **HUS (Hemolytic Uremic Syndrome):** This is primarily a triad of microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury (often Shiga-toxin mediated). Treatment is supportive (dialysis, fluids); splenectomy has no role in its management.

**3. Clinical Pearls for NEET-PG:**
*   **Indications for Splenectomy in ITP:** Failure of medical therapy (steroids are 1st line), contraindications to steroids, or emergency life-threatening bleeding.
*   **Vaccination Protocol:** For elective splenectomy, vaccinate **2 weeks before** surgery. For emergency splenectomy (like in acute ITP crisis), vaccinate **2 weeks after** surgery.
*   **Target Organisms:** *S. pneumoniae* (most common), *H. influenzae*, and *N. meningitidis*.
*   **Post-Splenectomy Blood Picture:** Look for **Howell-Jolly bodies** (most characteristic), Pappenheimer bodies, Heinz bodies, and target cells. [Practice more Surgery questions on OnCourse]

Surgery Questions

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