Specimen Collection and Processing — MCQs
Which of the following screening methods is NOT effective for early detection of cancer in asymptomatic women?
A female presents with a 1 × 1 cm thyroid swelling. What is the next best step in management?
Identify the given bone marrow biopsy instrument
A 45-year-old woman presents with a history of cervical erosion and spotting for the past 2 months. What is the next best step?
Which organism is considered the PRIMARY prototype for Ziehl-Neelsen (acid-fast) staining identification?
Which of the following is NOT a standard component of the triple test for breast cancer detection?
Which of the following thyroid carcinomas cannot be definitively diagnosed by fine needle aspiration cytology (FNAC)?
A case of solitary thyroid nodule; the investigation of choice is:
A child presents with grouped vesicles on the lips. What is the bedside investigation that you would like to do?
Order of drawing blood in vacutainers should be in the following sequence to prevent contamination?
Specimen Collection and Processing Indian Medical PG Practice Questions and MCQs
Question 1: Which of the following screening methods is NOT effective for early detection of cancer in asymptomatic women?
- A. Office endometrial washing for endometrial cancer
- B. USG in endometrial cancer
- C. CA-125 for ovarian cancer (Correct Answer)
- D. Pap smear for cervical cancer
Explanation: ***CA-125 for ovarian cancer*** - While elevated in some ovarian cancers, **CA-125 lacks sufficient sensitivity and specificity** as a stand-alone screening tool for early detection in asymptomatic women. - Its use for general population screening has **not been shown to reduce mortality** from ovarian cancer and can lead to **false positives** and unnecessary invasive procedures. - Major trials (UKCTOCS, PLCO) have not demonstrated mortality benefit from CA-125 screening. *Office endometrial washing for endometrial cancer* - While this involves collecting cells from the uterine lining for cytological analysis, **endometrial washing/cytology has poor sensitivity** and is not established as an effective screening method. - However, it has shown **some promise in research settings** for high-risk individuals, though it is not a standard or widely recommended screening approach. - **Endometrial biopsy** remains the gold standard for diagnosis in symptomatic women, but routine screening of asymptomatic women is not recommended. *USG in endometrial cancer* - **Transvaginal ultrasonography (TVUS)** can effectively measure **endometrial thickness** and is valuable for evaluating postmenopausal bleeding. - While not used for population-based screening of asymptomatic women, it aids in **risk stratification** and guiding further investigation like biopsy in symptomatic patients. - When used appropriately in symptomatic women, TVUS is a useful diagnostic adjunct. *Pap smear for cervical cancer* - The **Pap smear** is a highly effective and widely adopted screening method for **cervical cancer**, detecting precancerous and cancerous changes in cervical cells. - Its widespread use has **significantly reduced the incidence and mortality rates** of cervical cancer due to its ability to identify abnormalities early, allowing for timely intervention. - This is the gold standard for cancer screening with proven mortality benefit.
Question 2: A female presents with a 1 × 1 cm thyroid swelling. What is the next best step in management?
- A. I-131
- B. TSH (Correct Answer)
- C. TSH & T4
- D. T3 & T4
- E. FNAC
Explanation: ***Correct Option: TSH*** - **Thyroid-stimulating hormone (TSH)** is the most sensitive initial test to assess thyroid function when a thyroid nodule is discovered. - An abnormal TSH level (either high or low) can guide further investigation into whether the nodule is associated with a functional thyroid disorder. - **TSH should be the first test** according to American Thyroid Association guidelines for thyroid nodule evaluation. *Incorrect Option: I-131* - **I-131 (radioactive iodine therapy)** is a treatment modality for hyperthyroidism or thyroid cancer, not a diagnostic step for initial thyroid swelling evaluation. - Administering I-131 before assessing thyroid function would be inappropriate and could lead to unnecessary or harmful intervention. *Incorrect Option: TSH & T4* - While TSH is crucial, adding **T4 (thyroxine)** as an initial step is often not necessary if TSH is normal, as TSH alone effectively screens for primary thyroid dysfunction. - Measuring both TSH and T4 is typically reserved for situations where TSH is abnormal or when central hypothyroidism is suspected. *Incorrect Option: T3 & T4* - Measuring **T3 (triiodothyronine)** along with T4 as an initial screening for a thyroid nodule is generally not recommended. - T3 levels are primarily used to diagnose **hyperthyroidism** or to evaluate the severity of thyrotoxicosis after an abnormal TSH and T4 have been identified. *Incorrect Option: FNAC* - While **Fine Needle Aspiration Cytology (FNAC)** is an essential diagnostic tool for thyroid nodules, it is typically performed after TSH assessment. - FNAC is indicated for nodules >1 cm with suspicious ultrasound features, but **functional assessment with TSH comes first** to rule out hyperfunctioning nodules.
Question 3: Identify the given bone marrow biopsy instrument
- A. Jamshidi needle (Correct Answer)
- B. Salah needle
- C. Tru-cut needle
- D. Vim Silverman needle
Explanation: ***Jamshidi needle*** - The image displays a **Jamshidi needle**, characterized by its **tapered, beveled tip** designed to facilitate entry into the bone and procure an intact core of bone marrow. - This needle is widely considered the **gold standard** for bone marrow biopsy due to its effectiveness in obtaining high-quality trephine samples. *Salah needle* - A Salah needle is primarily used for **bone marrow aspiration**, not typically for a trephine biopsy, and it has a different design meant for aspirating liquid marrow. - It features a **shorter, sturdier design** with a sharp bevel, optimized for safely extracting marrow fluid. *Tru-cut needle* - The Tru-cut needle is primarily designed for obtaining **soft tissue biopsies** (e.g., liver, kidney, prostate) and is not typically used for bone marrow biopsies. - Its mechanism involves an inner cutting stylet and an outer cutting cannula, which is unsuitable for penetrating dense bone and retrieving a bone core. *Vim Silverman needle* - The Vim Silverman needle is also designed for **soft tissue biopsies**, similar to the Tru-cut, and not specifically for bone marrow. - It utilizes a split needle design to capture tissue, which is not appropriate for obtaining a solid bone marrow core.
Question 4: A 45-year-old woman presents with a history of cervical erosion and spotting for the past 2 months. What is the next best step?
- A. LBC + HPV (Correct Answer)
- B. Pap smear + HSV
- C. Pap smear + HBV
- D. LBC + HSV
Explanation: ***LBC + HPV*** - Cervical erosion and spotting are concerning for **cervical intraepithelial neoplasia (CIN)** or **cervical cancer**, making **Liquid-Based Cytology (LBC)** the appropriate screening method. - **Human Papillomavirus (HPV) testing** is crucial as persistent high-risk HPV infection is the primary cause of cervical cancer and helps in risk stratification and management. *Pap smear + HSV* - A **routine Pap smear** (conventional cytology) is less sensitive than LBC for detecting abnormal cervical cells and is generally being phased out by LBC. - **Herpes Simplex Virus (HSV)** causes genital herpes and is not directly associated with cervical cancer, thus testing for it in this context is not the most appropriate immediate next step. *Pap smear + HBV* - As mentioned, a **routine Pap smear** is not the preferred method for cervical cancer screening compared to LBC. - **Hepatitis B Virus (HBV)** causes liver disease and is entirely unrelated to cervical pathology; therefore, testing for it would be irrelevant to the patient's symptoms. *LBC + HSV* - While **LBC** is the correct advanced cytology method, adding **HSV testing** is not indicated as HSV does not cause cervical cancer or intraepithelial lesions that present with cervical erosion and spotting. - Focus should be on identifying potential malignancy or pre-malignant changes with HPV co-testing, not sexually transmitted infections unrelated to cancer risk.
Question 5: Which organism is considered the PRIMARY prototype for Ziehl-Neelsen (acid-fast) staining identification?
- A. Escherichia coli
- B. Mycobacterium tuberculosis (Correct Answer)
- C. Streptococcus pneumoniae
- D. Clostridium difficile
Explanation: ***Mycobacterium tuberculosis*** - The **Ziehl-Neelsen (ZN) stain** is the classic **acid-fast staining** technique used to identify **Mycobacterium species**, particularly **M. tuberculosis** - **Mycobacteria** possess high content of **mycolic acid** (60-90 carbon fatty acids) in their cell wall, making them resistant to decolorization by acid-alcohol - After staining with **carbol fuchsin** (heated), acid-fast bacilli retain the **red/pink color** while non-acid-fast organisms are decolorized and counterstained blue - M. tuberculosis is the **prototype organism** for acid-fast staining and remains the primary clinical application of ZN stain - **Note:** Modified ZN stain (using weaker 1% H2SO4) is used for **weakly acid-fast organisms** like Nocardia and Cryptosporidium *Streptococcus pneumoniae* - This is a **Gram-positive coccus** identified by **Gram staining**, not acid-fast staining - Appears as lancet-shaped diplococci on Gram stain - Lacks mycolic acid in cell wall and cannot retain carbol fuchsin after acid-alcohol decolorization *Escherichia coli* - This is a **Gram-negative bacillus** with thin peptidoglycan layer and outer membrane - Identified by **Gram staining** (appears pink/red) and biochemical tests - Not acid-fast and would be completely decolorized in ZN staining procedure *Clostridium difficile* - This is an **anaerobic, Gram-positive, spore-forming bacillus** - Identified by **Gram staining** and anaerobic culture - Lacks mycolic acid and acid-fast properties, making it unsuitable for ZN staining
Question 6: Which of the following is NOT a standard component of the triple test for breast cancer detection?
- A. USG/ mammography
- B. Breast self examination (Correct Answer)
- C. Clinical examination
- D. FNAC/ trucut biopsy
Explanation: ***Breast self examination*** - While **breast self-examination (BSE)** is important for **personal awareness** and **early detection**, it is not considered a standard component of the diagnostic "triple test" for breast cancer, which aims for definitive diagnosis. - The traditional triple test comprises **clinical examination**, **imaging** (mammography/ultrasound), and **pathological assessment** (FNAC/biopsy). *USG/ mammography* - **Mammography** and **ultrasonography (USG)** are crucial imaging modalities and an integral part of the **triple test**, providing detailed anatomical information about breast lesions. - They help characterize masses detected clinically and guide biopsy procedures, contributing significantly to diagnosis. *FNAC/ trucut biopsy* - **Fine needle aspiration cytology (FNAC)** and **tru-cut biopsy** are essential for **histopathological diagnosis**, confirming malignancy and determining tumor characteristics. - This is the third component of the triple test, providing a definitive cellular or tissue diagnosis. *Clinical examination* - A **thorough clinical breast examination** by a healthcare professional is the first step in the triple test, identifying palpable masses or other suspicious signs. - It involves **inspection** and **palpation** to assess breast tissue and lymph nodes.
Question 7: Which of the following thyroid carcinomas cannot be definitively diagnosed by fine needle aspiration cytology (FNAC)?
- A. Anaplastic carcinoma of thyroid
- B. Medullary carcinoma of thyroid
- C. Follicular carcinoma of thyroid (Correct Answer)
- D. Papillary carcinoma of thyroid
Explanation: ***Follicular carcinoma of thyroid*** - The definitive diagnosis of **follicular carcinoma** requires the presence of **capsular or vascular invasion**, which cannot be assessed through **fine needle aspiration cytology (FNAC)** alone [1], [5]. - FNA may show features suggestive of follicular neoplasm (e.g., hypercellularity with microfollicles), but differentiation from **follicular adenoma** requires histological examination of the excised specimen [1], [4]. *Anaplastic carcinoma of thyroid* - **Anaplastic carcinoma** is highly aggressive and characterized by **pleomorphic, bizarre cells** that are easily identifiable on FNAC [2], [5]. - The distinctive cytological features, including **spindle cells, giant cells, and rapid cellular atypia**, allow for a relatively straightforward diagnosis via FNAC [2]. *Medullary carcinoma of thyroid* - **Medullary carcinoma** cells have characteristic cytological features, such as **plasmacytoid appearance**, **amyloid deposition**, and **neuroendocrine granules**, which can be identified on FNAC [5]. - Confirmation can be made by **immunohistochemical staining for calcitonin** on the FNA sample [5]. *Papillary carcinoma of thyroid* - **Papillary carcinoma** has distinct cytological features, including **orphan Annie eye nuclei**, **intranuclear grooves**, **pseudoinclusions**, and **papillary structures**, readily identified by FNAC [3]. - These features are highly specific and often allow for a definitive diagnosis of papillary thyroid carcinoma [3]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1100-1101. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Endocrine System, pp. 1101-1102. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 429-430. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 428-429. [5] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 430-431.
Question 8: A case of solitary thyroid nodule; the investigation of choice is:
- A. T3, T4 estimation
- B. Thyroid scan
- C. FNAC (Correct Answer)
- D. Excision biopsy
Explanation: ***Correct: FNAC*** - **Fine needle aspiration cytology (FNAC)** is the most important and definitive diagnostic tool for evaluating the malignancy risk of a **solitary thyroid nodule**. - It's a minimally invasive, cost-effective procedure with high sensitivity and specificity in differentiating **benign** from **malignant** lesions. - FNAC is recommended as the **first-line investigation** by major thyroid guidelines (ATA, BTA). *Incorrect: T3, T4 estimation* - **Thyroid hormone levels (T3, T4)** primarily assess thyroid function (hyperthyroidism or hypothyroidism), not the **malignancy potential** of a nodule itself. - While thyroid dysfunction can sometimes be associated with nodules, these tests alone cannot definitively diagnose or rule out cancer. - Thyroid function tests are complementary but not the primary investigation for nodule characterization. *Incorrect: Thyroid scan* - A **thyroid scan** (using radioactive iodine) helps determine if a nodule is "hot" (hyperfunctioning/benign) or "cold" (non-functioning/potentially malignant). - However, it cannot definitively differentiate between benign and malignant **cold nodules**, which require further investigation, typically FNAC. - Thyroid scanning has largely been superseded by ultrasound and FNAC in modern practice. *Incorrect: Excision biopsy* - **Excision biopsy** (surgical removal) is a treatment for a thyroid nodule rather than the initial investigation of choice. - It is typically performed when **FNAC results are indeterminate** or suspicious for malignancy, or when the nodule is significantly large or symptomatic. - This is an invasive procedure with surgical risks and is not appropriate as a first-line investigation.
Question 9: A child presents with grouped vesicles on the lips. What is the bedside investigation that you would like to do?
- A. Wood's lamp
- B. Slit skin smear
- C. Tzanck smear (Correct Answer)
- D. KOH
Explanation: ***Tzanck smear*** - A **Tzanck smear** is a rapid bedside test that can identify **multinucleated giant cells**, which are seen in herpes simplex virus infections. - The presence of **grouped vesicles on the lips** is highly suggestive of **herpes labialis** (HSV-1), which is primarily a **clinical diagnosis**. - Among the options provided, Tzanck smear is the only relevant bedside investigation, though it has **limited sensitivity and specificity** and **cannot distinguish between HSV and VZV**. - In modern practice, **PCR or direct immunofluorescence** are preferred when laboratory confirmation is needed, but Tzanck smear remains a low-cost option in resource-limited settings. *Wood's lamp* - A Wood's lamp uses **ultraviolet light** to detect certain fungal or bacterial infections by revealing characteristic fluorescence. - It is useful for conditions like **tinea capitis** (green fluorescence) and **erythrasma** (coral-red fluorescence), but has no role in diagnosing viral vesicular lesions. *Slit skin smear* - A **slit skin smear** is used to detect **acid-fast bacilli** in the diagnosis of **leprosy**. - It is not indicated for vesicular lesions and is irrelevant to herpes simplex infection. *KOH* - A **KOH (potassium hydroxide) mount** is used to diagnose **fungal infections** by dissolving keratinocytes and revealing fungal hyphae or spores. - It has no utility in diagnosing viral infections such as herpes simplex.
Question 10: Order of drawing blood in vacutainers should be in the following sequence to prevent contamination?
- A. Grey, Blue, Red, Violet
- B. Blue, Red, Violet, Grey (Correct Answer)
- C. Blue, Violet, Red, Grey
- D. Red, Blue, Violet, Grey
Explanation: ***Blue, Red, Violet, Grey*** - This sequence follows the **CLSI (Clinical and Laboratory Standards Institute) order of draw** guidelines, which are critical for preventing **cross-contamination** between additives of different vacutainers. - The order starts with tubes for **coagulation studies** (blue top with sodium citrate), followed by serum tubes (red top), EDTA tubes (violet top for hematology), and finally glycolytic inhibitor tubes (grey top for glucose). - This prevents tissue thromboplastin contamination and anticoagulant carryover that could affect laboratory test results. *Grey, Blue, Red, Violet* - This order is incorrect as it places the **grey top tube** (containing fluoride/oxalate) first, which could contaminate subsequent tubes with its additives and affect tests. - The **blue top tube** for coagulation studies should come early in the sequence to minimize tissue thromboplastin contamination. *Blue, Violet, Red, Grey* - This sequence is incorrect because the **violet top tube** (EDTA) is placed before the **red top tube** (serum). - **EDTA contamination** can chelate calcium and other cations, interfering with chemistry tests performed on serum in the red top tube. *Red, Blue, Violet, Grey* - This order is incorrect as the **red top tube** is placed first, followed by the **blue top tube** (citrate). - The blue top tube should precede tubes with clot activators to **prevent tissue thromboplastin** from contaminating coagulation samples, which would lead to falsely shortened clotting times.
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