The following cost-effective investigations are routinely recommended in the screening of antenatal mothers, EXCEPT:

Echocardiography for cardiac disease

An infant presented with vomiting, malnutrition, blue eyes, blonde hair & fair skin. On investigation, Guthrie test was positive. All are true regarding this disease EXCEPT:

Hypopigmentation due to tryptophan deficiency

Phenyl acetate positive in urine

Screening for colorectal cancer is recommended when?

Early diagnosis can change the disease course due to effective treatment.

The condition has a low case fatality rate.

Diagnostic tools are not available.

There is no effective treatment available.

Which of the following is used for initial screening of auditory function in a neonate?

Auditory brainstem response (ABR)

18 weeks pregnant female presents with no high risk of NTD and low risk of trisomy 21 on quad test. What is the most appropriate next step in management?

Perform a detailed fetal ultrasound.

Repeat non-invasive screening test.

Perform invasive diagnostic testing.

Perform amniotic fluid analysis.

4 day old breastfed neonate, otherwise well, term neonate presented with jaundice, on testing the bilirubin level was found to be 18 mg/dl. Which of the following is the best step of management?

Start phototherapy and continue breast feeding

Stop breast feeding and do phototherapy

Start iv fluids and give phototherapy

Newborn Screening for USMLE Step 3: High-Yield Psychiatry Lessons

NBS Basics & Indian Scene - First Steps, First Screens

Definition: Population-wide testing of newborns for specific treatable disorders before symptoms manifest.
Goals: Early diagnosis & intervention to ↓ morbidity/mortality, improve Quality of Life (QoL).
Wilson-Jungner Criteria (adapted for NBS): Key principles for justifying a screening program.
- 📌 Mnemonic: SCATTER
  - Serious Condition: Disease poses a significant health burden.
  - Acceptable Test: Reliable, valid, and acceptable to population.
  - Treatment Effective: Available treatment that improves prognosis.
  - Resources: Adequate facilities for diagnosis, treatment, and follow-up.
NBS in India:
- No unified national program; state-level variations.
- IAP Recommendations: Strong advocacy for universal NBS.
- RBSK: Includes some NBS components (e.g., Congenital Hypothyroidism (CH), hearing loss).
- Active programs in states like Kerala, Goa; pilot projects elsewhere.
Commonly Screened Conditions (India): Congenital Hypothyroidism (CH), Congenital Adrenal Hyperplasia (CAH), G6PD deficiency. Others include PKU, Galactosemia depending on regional prevalence & resources.

⭐ Newborn screening aims for early identification of infants with treatable conditions before they become symptomatic.

The "Must-Know" Disorders - Tiny Clues, Major Conditions

⭐ Congenital Hypothyroidism is the most common preventable cause of intellectual disability worldwide.

Disorder	Defect (Enzyme/Protein)	Inheritance	Screening Test	Confirmatory Test	Key Features (Untreated) / Benefit of Early Detection
Congenital Hypothyroidism (CH)	Thyroid dysgenesis/dyshormonogenesis	Sporadic	↑TSH (> 20 µIU/mL), ↓T4	Repeat TSH, Free T4; Thyroid scan/USG	Prevents severe intellectual disability, growth failure. Untreated: coarse facies, umbilical hernia, prolonged jaundice.
Phenylketonuria (PKU)	Phenylalanine hydroxylase (PAH) deficiency	AR	↑Phenylalanine (Phe) levels (MS/MS)	Quantitative plasma Phe; Genetic testing	Prevents severe intellectual disability, seizures, eczema. Untreated: mousy odor. 📌 PKU: Phenylalanine Kills Understanding.
Galactosemia (Classical)	Galactose-1-Phosphate Uridyltransferase (GALT)	AR	↓GALT activity, ↑Total Galactose/Gal-1-P	GALT enzyme assay (RBCs); Genetic testing	Prevents FTT, jaundice, hepatomegaly, cataracts, E. coli sepsis, intellectual disability.
Congenital Adrenal Hyperplasia (CAH)	21-hydroxylase deficiency (>90%)	AR	↑17-hydroxyprogesterone (17-OHP)	ACTH stim test; ↓Na, ↑K; Genetic testing	Prevents salt-wasting crisis, ambiguous genitalia (females), virilization. Ensures correct sex assignment, normal growth.
G6PD Deficiency	Glucose-6-Phosphate Dehydrogenase	X-linked	↓G6PD enzyme activity (fluorescent spot test)	Quantitative G6PD enzyme assay	Avoids triggers for neonatal jaundice & acute hemolytic anemia (drugs, infections, fava beans).
Biotinidase Deficiency	Biotinidase enzyme deficiency	AR	↓Biotinidase activity (MS/MS)	Serum biotinidase assay; Genetic testing	Prevents seizures, hypotonia, rash, alopecia, developmental delay with biotin supplementation.

Screening Logistics & Follow-Up - Dots, Drops, Decisions

Sample Collection (Dried Blood Spot - DBS):
- Timing: Ideal 24-72 hours of age; after adequate protein feeding (e.g., PKU).
- Site: Heel prick (medial/lateral plantar surface).
- Method: Blood drops on filter paper (Guthrie card).
Factors Affecting Results: Prematurity (transient ↑17-OHP, ↓T4), TPN, blood transfusion (masking), antibiotics, maternal diet/meds.
Interpretation & Recall: Use analyte-specific cut-offs; manage false positives/negatives; clear recall criteria for positive screens.
Follow-up Protocol:
- Prompt confirmatory tests (e.g., MS/MS, enzyme assays, DNA).
- Specialist referral, timely treatment initiation.
- Genetic counseling for family.
Other Universal Screenings:
- UNHS: OAE (screening), BERA (diagnostic if OAE fails).
- CCHD: Pulse oximetry (24-48 hrs, pre- & post-ductal $SpO_2$ difference/low saturation).

⭐ A positive newborn screen is not a diagnosis but indicates high risk and requires prompt confirmatory testing.

High‑Yield Points - ⚡ Biggest Takeaways

NBS facilitates early diagnosis and management of critical congenital conditions.

Optimal sampling: 24-72 hours post-birth, after feeding, via heel prick.

Core Indian panel: Congenital Hypothyroidism (CH), CAH, G6PD deficiency.

Tandem Mass Spectrometry (TMS) allows simultaneous screening for numerous disorders.

Phenylketonuria (PKU) detected by Guthrie test or TMS.

Screen for Galactosemia (GALT deficiency) and Biotinidase deficiency.

Pulse oximetry for Critical Congenital Heart Disease (CCHD) screening is vital.

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