After giving BCG, scar gets formed in:

Appeared in: BHU NO-2019

Explanation

The formation of a BCG scar is the final stage of a local inflammatory reaction that takes several weeks to complete.
Following the injection, a papule appears at 2-3 weeks, which may then evolve into an ulcer.
The ulcer heals spontaneously, and a permanent scar is typically formed within 6 to 12 weeks.
The option of '2 months' (approximately 8 weeks) falls directly within this healing and scarring timeframe, making it the correct answer.

Option A: At 3 days post-vaccination, the initial injection wheal has disappeared, and the characteristic local reaction (papule formation) has not yet begun.
Option B: At 2 weeks, the local reaction is just beginning with the appearance of a small papule. The process of ulceration and healing to form a scar has not started.
Option D: At 1 month (4 weeks), the lesion is typically a well-formed papule or a shallow ulcer. It is an active phase of the reaction, not the healed scar stage.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Timeline of BCG vaccine scar formation as background academic context rather than a clinical decision trigger.
The presence of a BCG scar is a common, though not absolute, indicator of successful vaccination and is often checked during health surveys and clinical assessments in countries like India.
Nurses play a crucial role in educating parents about the normal progression of the BCG reaction. This counseling helps prevent unnecessary anxiety and inappropriate local treatment (e.g., applying creams or bandages), which can interfere with the immune response.
What if? If no scar is visible after 3 months, it may suggest vaccination failure. While the Indian national immunization schedule does not recommend routine revaccination, a pediatrician may assess the child's overall health and TB risk factors to decide on further action.

How to Approach the Question

First, identify the core of the question, which is the specific time it takes for a BCG scar to form.
Recall the sequence of events following a BCG injection: an initial wheal, followed by a papule, then an ulcer, and finally healing into a scar.
Associate each stage with its approximate timeline. Remember that the scar is the final stage of this process.
The papule appears at 2-3 weeks, ulcerates around 4-6 weeks, and the healing/scarring phase occurs from 6 to 12 weeks.
Evaluate the given options against this timeline. 3 days, 2 weeks, and 1 month are all too early, representing the initial or active inflammatory stages.
Select the option that best fits the 6-12 week window for scar formation, which is '2 months'.

Concept Tested & Keywords

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E6 Parks TextBook of Preventive & Social Medicine part 1 — Subpart B (pp 202-403 of 604) p. 42-44

Practise the full BHU NO-2019

Attempt every question from this paper in a timed mock, then review the full solution for each one.