Special population considerations US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for Special population considerations. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
Special population considerations US Medical PG Question 1: A 28-year-old woman presents to her physician for follow-up. She was found to be HIV-positive 9 months ago. Currently she is on ART with lamivudine, tenofovir, and efavirenz. She has no complaints and only reports a history of mild respiratory infection since the last follow-up. She is also allergic to egg whites. Her vital signs are as follows: the blood pressure is 120/75 mm Hg, the heart rate is 73/min, the respiratory rate is 13/min, and the temperature is 36.7°C (98.0°F). She weighs 68 kg (150 lb), and there is no change in her weight since the last visit. On physical examination, she appears to be pale, her lymph nodes are not enlarged, her heart sounds are normal, and her lungs are clear to auscultation. Her total blood count shows the following findings:
Erythrocytes 3.2 x 106/mm3
Hematocrit 36%
Hgb 10 g/dL
Total leukocyte count 3,900/mm3
Neutrophils 66%
Lymphocytes 24%
Eosinophils 3%
Basophils 1%
Monocytes 7%
Platelet count 280,000/mm3
Her CD4+ cell count is 430 cells/µL. The patient tells you she would like to get an influenza vaccination as flu season is coming. Which of the following statements is true regarding influenza vaccination in this patient?
- A. As long as the patient is anemic, she should not be vaccinated.
- B. Influenza vaccination is contraindicated in HIV-positive patients because of the serious complications they can cause in immunocompromised people.
- C. Inactivated or recombinant influenza vaccines fail to induce a sufficient immune response in patients with CD4+ cell counts under 500 cells/µL.
- D. Nasal-spray influenza vaccine is the best option for vaccination in this patient.
- E. The patient can receive approved recombinant or inactivated influenza vaccines, with egg-free formulations preferred due to her egg allergy. (Correct Answer)
Special population considerations Explanation: **The patient can receive approved recombinant or inactivated influenza vaccines, with egg-free formulations preferred due to her egg allergy.**
- Patients with HIV, regardless of their CD4+ count, should receive the **inactivated influenza vaccine** annually due to their increased risk of severe influenza complications.
- Given the patient's reported egg allergy, an **egg-free vaccine formulation**, such as a recombinant injectable influenza vaccine (RIV4) or cell-culture-based inactivated influenza vaccine (ccIIV4), is the preferred choice to minimize allergic reactions.
*As long as the patient is anemic, she should not be vaccinated.*
- **Anemia** is not a contraindication for receiving the influenza vaccine; the benefits of vaccination typically outweigh any risks associated with mild anemia.
- While the patient is anemic (Hgb 10 g/dL), this condition does not prevent her from safely receiving an **inactivated influenza vaccine**.
*Influenza vaccination is contraindicated in HIV-positive patients because of the serious complications they can cause in immunocompromised people.*
- This statement is incorrect; **inactivated influenza vaccines** are recommended for HIV-positive individuals, as they are not live vaccines and cannot cause influenza.
- HIV-positive patients are at higher risk for severe influenza complications, making vaccination even more crucial, not contraindicated.
*Inactivated or recombinant influenza vaccines fail to induce a sufficient immune response in patients with CD4+ cell counts under 500 cells/µL.*
- While the immune response to vaccines can be attenuated in HIV patients with lower CD4+ counts, even a partial response offers some protection and is better than no vaccination.
- The **guidelines for HIV patients** recommend influenza vaccination regardless of CD4+ count, emphasizing the importance of any induced immunity.
*Nasal-spray influenza vaccine is the best option for vaccination in this patient.*
- The **nasal-spray influenza vaccine (LAIV)** is a **live-attenuated vaccine**, which is generally contraindicated in immunocompromised individuals, including those with HIV, due to the risk of active infection.
- HIV patients should receive **inactivated or recombinant influenza vaccines**, not live-attenuated formulations.
Special population considerations US Medical PG Question 2: An 11-year-old boy is brought to his pediatrician by his parents for the routine Tdap immunization booster dose that is given during adolescence. Upon reviewing the patient’s medical records, the pediatrician notes that he was immunized according to CDC recommendations, with the exception that he received a catch-up Tdap immunization at the age of 8 years. When the pediatrician asks the boy’s parents about this delay, they inform the doctor that they immigrated to this country 3 years ago from Southeast Asia, where the child had not been immunized against diphtheria, tetanus, and pertussis. Therefore, he received a catch-up series at 8 years of age, which included the first dose of the Tdap vaccine. Which of the following options should the pediatrician choose to continue the boy’s immunization schedule?
- A. A single dose of Td vaccine at 18 years of age
- B. A single dose of Td vaccine now
- C. No further vaccination needed
- D. A single dose of Tdap vaccine now
- E. A single dose of Tdap vaccine at 13 years of age (Correct Answer)
Special population considerations Explanation: ***A single dose of Tdap vaccine at 13 years of age***
- The CDC recommends a **minimum interval of 5 years** between Tdap doses when Tdap is given as part of a catch-up series.
- Since this patient received his first Tdap at age 8, the earliest he should receive the adolescent booster is at **age 13** (5 years later).
- This timing ensures adequate spacing while still providing the recommended adolescent booster for **pertussis, tetanus, and diphtheria** protection.
- The 5-year interval prevents excessive antigen exposure and optimizes immune response.
*A single dose of Tdap vaccine now*
- Giving Tdap now would result in only a **3-year interval** from the previous Tdap dose at age 8.
- This violates the CDC recommendation of a **minimum 5-year interval** between Tdap doses.
- Shorter intervals may increase local reactogenicity without improving protection.
*A single dose of Td vaccine now*
- While this would provide tetanus and diphtheria protection, it would **not protect against pertussis**, which is a critical component of adolescent vaccination.
- The Tdap vaccine is specifically recommended for adolescents to boost waning pertussis immunity.
- Additionally, giving it now would still be earlier than the recommended 5-year interval from the previous pertussis-containing vaccine.
*A single dose of Td vaccine at 18 years of age*
- This option would result in a **10-year gap** from the last pertussis-containing vaccine, leaving the adolescent vulnerable during high-risk years.
- The adolescent Tdap booster is specifically timed for ages 11-13 to protect during peak transmission periods in middle and high school.
- Waiting until 18 would miss the critical window for pertussis protection.
*No further vaccination needed*
- While the patient completed a catch-up series, the CDC still recommends an **adolescent Tdap booster** even for those who received Tdap in a catch-up series.
- The adolescent booster is important to maintain immunity against pertussis, which wanes significantly over time.
- The booster should be given at age 13 to maintain the 5-year minimum interval.
Special population considerations US Medical PG Question 3: A 24-year-old woman with HIV infection comes to the physician for a follow-up examination. She has been inconsistently taking combined antiretroviral therapy for the past 5 years. She did not receive any childhood vaccinations because her parents were against them. During the consultation, the patient says that she wants to catch up on the missed vaccinations. Laboratory studies show a CD4+ T lymphocyte cell count of 180/mm3. Administration of the vaccine against which of the following agents should be avoided in this patient?
- A. Clostridium tetani
- B. Human papillomavirus
- C. Varicella zoster virus (Correct Answer)
- D. Bordetella pertussis
- E. Haemophilus influenzae
Special population considerations Explanation: ***Varicella zoster virus***
- The **varicella zoster vaccine is a live attenuated vaccine**, which is generally contraindicated in individuals with severe **immunodeficiency**, such as HIV patients with a **CD4+ count below 200 cells/mm³**.
- Administering a live vaccine to an immunocompromised patient can lead to **uncontrolled viral replication** and potentially cause the disease it is meant to prevent.
*Clostridium tetani*
- The **tetanus vaccine** is a **toxoid vaccine**, meaning it contains inactivated bacterial toxins, not live organisms.
- It is **safe and recommended** for individuals with HIV, regardless of their CD4+ count, to provide protection against tetanus.
*Human papillomavirus*
- The **HPV vaccine** is a **recombinant vaccine**, consisting of viral-like particles (VLPs) and containing no live virus.
- It is **safe and recommended** for HIV-positive individuals and helps prevent HPV-related cancers.
*Bordetella pertussis*
- The **pertussis vaccine** (part of DTaP or Tdap) is an **acellular vaccine**, containing purified bacterial components, not live bacteria.
- It is **safe and recommended** for HIV patients to protect against whooping cough.
*Haemophilus influenzae*
- The **Haemophilus influenzae type b (Hib) vaccine** is a **conjugate vaccine**, made from bacterial capsular polysaccharide linked to a carrier protein.
- It is **safe and recommended** for HIV-positive individuals, as they are at increased risk for invasive Hib disease.
Special population considerations US Medical PG Question 4: A 2-year-old boy is brought in by his parents to his pediatrician. The boy was born by spontaneous vaginal delivery at 39 weeks and 5 days after a normal pregnancy. The boy has received all age-appropriate vaccinations as of his last visit at 18 months of age. Of note, the boy has confirmed sickle cell disease and the only medication he takes is penicillin prophylaxis. The parents state that they plan on enrolling their son in a daycare, which requires documentation of up-to-date vaccinations. The pediatrician states that their son needs an additional vaccination at this visit, which is a polysaccharide vaccine that is not conjugated to protein. Which of the following matches this description?
- A. Pneumovax (Correct Answer)
- B. Menactra
- C. Prevnar
- D. Hib vaccine
- E. Live attenuated influenza vaccine
Special population considerations Explanation: ***Pneumovax***
- **Pneumovax** (PCV23, PPSV23) is a **polysaccharide vaccine** that is not conjugated to a protein carrier. Children with **sickle cell disease** should receive this vaccine due to their immunocompromised state and increased risk of encapsulated bacterial infections.
- The Centers for Disease Control and Prevention (CDC) recommends PPSV23 for children aged 2 years and older with chronic medical conditions such as **sickle cell disease**, usually administered 8 weeks after their last PCV13 dose.
*Menactra*
- **Menactra** is a **quadrivalent meningococcal conjugate vaccine** (MCV4), meaning it contains a polysaccharide antigen conjugated to a protein carrier.
- This vaccine primarily targets *Neisseria meningitidis* and is different from the pneumococcal vaccine required here.
*Prevnar*
- **Prevnar** (PCV13) is a **pneumococcal conjugate vaccine**, meaning its polysaccharide antigens are conjugated to a protein carrier.
- While important for children with sickle cell disease, the question specifically asks for a vaccination that is a **polysaccharide vaccine that is not conjugated to protein**.
*Hib vaccine*
- The **Hib vaccine** (against *Haemophilus influenzae* type b) is a **conjugate vaccine**, meaning its polysaccharide capsule is linked to a protein carrier to enhance immunogenicity, particularly in infants.
- This vaccine is typically given earlier in childhood and is not the "additional" unconjugated polysaccharide vaccine described.
*Live attenuated influenza vaccine*
- The **live attenuated influenza vaccine (LAIV)** is a live virus vaccine, not a polysaccharide vaccine.
- It is also contraindicated in individuals with certain immunocompromising conditions, such as some patients with sickle cell disease.
Special population considerations US Medical PG Question 5: A 7-year-old African-American boy presents to his physician with fatigue, bone and abdominal pain, and mild jaundice. The pain is dull and remitting, and the patient complains it sometimes migrates from one extremity to another. His mother reports that his jaundice and pain have occurred periodically for the past 5 years. At the time of presentation, his vital signs are as follows: the blood pressure is 80/50 mm Hg, the heart rate is 87/min, the respiratory rate is 17/min, and the temperature is 36.5°C (97.7°F). On physical examination, the patient appears to be pale with mildly icteric sclera and mucous membranes. On auscultation, there is a soft systolic ejection murmur, and palpation reveals hepatosplenomegaly. His musculoskeletal examination shows no abnormalities. Laboratory investigations show the following results:
Complete blood count
Erythrocytes
3.7 x 106/mm3
Hgb
11 g/dL
Total leukocyte count
Neutrophils
Lymphocytes
Eosinophils
Monocytes
Basophils
7,300/mm3
51%
40%
2%
7%
0
Platelet count
151,000/mm3
Chemistry
Total bilirubin
3.1 mg/dL (53 µmol/L)
Direct bilirubin
0.5 mg/dL (8.55 µmol/L)
A peripheral blood smear shows numerous sickle-shaped red blood cells. Among other questions, the patient’s mother asks you how his condition would influence his vaccination schedule. Which of the following statements is true regarding vaccination in this patient?
- A. The patient’s condition does not affect his chances to get any infection; thus, additional vaccinations are not advised.
- B. The patient should not receive meningococcal, pneumococcal, or Haemophilus influenzae vaccines, because they are likely to cause complications or elicit disease in his case.
- C. The patient should receive the pneumococcal polysaccharide vaccine as soon as possible, because he is at higher risk of getting pneumococcal infection than other children.
- D. The patient should receive serogroup B meningococcal vaccination at the age of 10 years. (Correct Answer)
- E. The patient should receive serogroup B meningococcal vaccination as soon as possible, because he is at higher risk of getting meningococcal infection than other children.
Special population considerations Explanation: ***The patient should receive serogroup B meningococcal vaccination at the age of 10 years.***
- Patients with **sickle cell disease** (SCD) have **functional asplenia**, increasing their risk for invasive meningococcal disease from encapsulated bacteria.
- The **MenACWY vaccine** should be given starting at age 2 months for high-risk children with asplenia, with boosters every 5 years.
- The **MenB vaccine series** is recommended specifically for individuals **10 years and older** with anatomic or functional asplenia, including SCD patients.
- This statement correctly identifies the age-appropriate timing for MenB vaccination according to **ACIP guidelines**.
*The patient should receive serogroup B meningococcal vaccination as soon as possible, because he is at higher risk of getting meningococcal infection than other children.*
- While SCD patients are at increased risk for meningococcal infections, the **MenB vaccine is not recommended before age 10 years**, even in high-risk patients.
- At age 7, this patient should receive **MenACWY** if not already vaccinated, but MenB vaccination should wait until age 10.
- The timing "as soon as possible" is incorrect for MenB vaccine in this 7-year-old patient.
*The patient's condition does not affect his chances to get any infection; thus, additional vaccinations are not advised.*
- This is completely false. **Sickle cell disease causes functional asplenia**, which dramatically increases the risk of overwhelming sepsis from encapsulated organisms (*S. pneumoniae*, *N. meningitidis*, *H. influenzae* type b).
- Additional vaccinations beyond the routine schedule are **essential and life-saving** for SCD patients.
*The patient should not receive meningococcal, pneumococcal, or Haemophilus influenzae vaccines, because they are likely to cause complications or elicit disease in his case.*
- This is dangerously incorrect. These vaccines are **specifically recommended and safe** for patients with SCD.
- Patients with functional asplenia are at **highest risk** for invasive disease from these encapsulated bacteria, making vaccination crucial.
- These vaccines do not cause complications or elicit disease in SCD patients; they are inactivated or subunit vaccines.
*The patient should receive the pneumococcal polysaccharide vaccine as soon as possible, because he is at higher risk of getting pneumococcal infection than other children.*
- While SCD patients are at high risk for pneumococcal infection, the vaccination schedule is specific: **PCV13** in infancy, followed by **PPSV23** at age 2 years and older.
- At age 7, if not previously vaccinated, catch-up vaccination is needed, but "as soon as possible" without specifying the proper sequence (PCV13 first, then PPSV23) and "polysaccharide vaccine" alone is imprecise.
- The correct answer focuses on MenB at age 10, which is the most specific guideline-based recommendation among the options.
Special population considerations US Medical PG Question 6: A 20-year-old primigravid woman comes to the physician in October for her first prenatal visit. She has delayed the visit because she wanted a “natural birth” but was recently convinced to get a checkup after feeling more tired than usual. She feels well. Menarche was at the age of 12 years and menses used to occur at regular 28-day intervals and last 3–7 days. The patient emigrated from Mexico 2 years ago. Her immunization records are unavailable. Pelvic examination shows a uterus consistent in size with a 28-week gestation. Laboratory studies show:
Hemoglobin 12.4 g/dL
Leukocyte count 8,000/mm3
Blood group B negative
Serum
Glucose 88 mg/dL
Creatinine 1.1 mg/dL
TSH 3.8 μU/mL
Rapid plasma reagin negative
HIV antibody negative
Hepatitis B surface antigen negative
Urinalysis shows no abnormalities. Urine culture is negative. Chlamydia and gonorrhea testing are negative. A Pap smear is normal. Administration of which of the following vaccines is most appropriate at this time?
- A. Varicella and influenza
- B. Varicella and Tdap
- C. Influenza only
- D. Tdap and influenza (Correct Answer)
- E. Hepatitis B and MMR
Special population considerations Explanation: ***Tdap and influenza***
- The **Tdap vaccine** is recommended for pregnant women during each pregnancy, preferably between **27 and 36 weeks gestation**, to provide passive immunity to the newborn against pertussis. The patient is at 28 weeks gestation.
- The **influenza vaccine** is recommended for all pregnant women, regardless of trimester, during flu season (October in this case) to protect both the mother and the newborn.
*Varicella and influenza*
- The **varicella vaccine is contraindicated in pregnancy** because it is a live attenuated vaccine.
- While influenza vaccine is appropriate, administering varicella vaccine is not.
*Varicella and Tdap*
- As mentioned, the **varicella vaccine is contraindicated in pregnancy** due to its live attenuated nature.
- Although Tdap is appropriate, varicella is not.
*Influenza only*
- While the **influenza vaccine is appropriate**, the **Tdap vaccine** is also indicated for this patient given her gestational age and the benefits for the newborn.
- Administering only influenza would miss an opportunity to provide crucial pertussis protection.
*Hepatitis B and MMR*
- The **Hepatitis B vaccine** is safe in pregnancy if indicated, but the patient tested **Hepatitis B surface antigen negative**, suggesting no current infection and no immediate need for vaccination based on the provided information.
- The **MMR vaccine is contraindicated in pregnancy** because it is a live attenuated vaccine.
Special population considerations US Medical PG Question 7: A 28-year-old woman gives birth to a 2.2 kg child while on vacation. The mother's medical records are faxed to the hospital and demonstrate the following on hepatitis panel: hepatitis B surface antigen (HbsAg) positive, anti-hepatitis B core antigen (anti-HbcAg) positive, hepatitis C RNA is detected, hepatitis C antibody is reactive. Which of the following should be administered to the patient's newborn child?
- A. Hepatitis B vaccine, ledipasvir/sofosbuvir
- B. Hepatitis B IVIG and vaccine (Correct Answer)
- C. Hepatitis B IVIG, hepatitis B vaccine and ledipasvir/sofosbuvir
- D. Hepatitis B IVIG now, hepatitis B vaccine in one month
- E. Hepatitis B vaccine
Special population considerations Explanation: ***Hepatitis B IVIG and vaccine***
- The mother is **HBsAg positive** and **anti-HBcAg positive**, indicating a **chronic hepatitis B infection**. To prevent vertical transmission, the neonate must receive both **Hepatitis B Immune Globulin (HBIG)** and the **Hepatitis B vaccine** within 12 hours of birth.
- While the mother also has **Hepatitis C (HCV) RNA detected** and **HCV antibody reactive**, there is currently no preventative measure for HCV transmission to the newborn at birth, as antiviral medications like ledipasvir/sofosbuvir are not administered to neonates for this purpose.
*Hepatitis B vaccine, ledipisvir/sofosbuvir*
- Administering ledipasvir/sofosbuvir to the newborn is **not indicated** for preventing vertical transmission of Hepatitis C; these antivirals are used for treating HCV infection in adults and older children.
- While the Hepatitis B vaccine is necessary, it is **insufficient alone** for preventing perinatal HBV transmission in infants born to HBsAg-positive mothers.
*Hepatitis B IVIG, hepatitis B vaccine and ledipisvir/sofosbuvir*
- **Ledipasvir/sofosbuvir** is not a recommended prophylactic or treatment measure for newborns to prevent hepatitis C infection.
- While HBIG and the vaccine are correct for Hepatitis B, the addition of HCV antivirals for the neonate is **inappropriate**.
*Hepatitis B IVIG now, hepatitis B vaccine in one month*
- Both **HBIG** and the **first dose of the Hepatitis B vaccine** must be given **within 12 hours of birth** to be maximally effective in preventing perinatal HBV transmission. Delaying the vaccine dose significantly reduces its protective efficacy.
- This regimen would leave the newborn **unprotected** for a crucial period during which HBV transmission is most likely.
*Hepatitis B vaccine*
- Giving only the **Hepatitis B vaccine** is **insufficient** for an infant born to an HBsAg-positive mother.
- In such cases, **HBIG** is also required to provide immediate passive immunity and maximize protection against perinatal HBV infection, which has a high risk of chronicity.
Special population considerations US Medical PG Question 8: A 68-year-old woman with chronic idiopathic thrombocytopenic purpura (ITP) presents to her hematologist for routine follow-up. She has been on chronic corticosteroids for her ITP, in addition to several treatments with intravenous immunoglobulin (IVIG) and rituximab. Her labs today reveal a white blood cell count of 8, hematocrit of 35, and platelet count of 14. Given her refractory ITP with persistent thrombocytopenia, her hematologist recommends that she undergo splenectomy. What is the timeline for vaccination against encapsulated organisms and initiation of penicillin prophylaxis for this patient?
- A. Vaccinate: at the time of surgery; Penicillin: at time of surgery for 5 years
- B. Vaccinate: 2 weeks prior to surgery; Penicillin: at time of surgery for 5 years (Correct Answer)
- C. Vaccinate: 2 weeks prior to surgery; Penicillin: at time of surgery for an indefinite course
- D. Vaccinate: 2 weeks prior to surgery; Penicillin: 2 weeks prior to surgery for an indefinite course
- E. Vaccinate: at the time of surgery; Penicillin: 2 weeks prior to surgery for an indefinite course
Special population considerations Explanation: **Vaccinate: 2 weeks prior to surgery; Penicillin: at time of surgery for 5 years**
- **Vaccination against encapsulated organisms** (e.g., *Streptococcus pneumoniae*, *Haemophilus influenzae type b*, *Neisseria meningitidis*) should ideally occur **2 weeks prior to splenectomy**. This allows sufficient time for the patient to mount an immune response and develop protective antibodies before the spleen's critical role in filtering blood and producing opsonizing antibodies against these bacteria is removed.
- **Penicillin prophylaxis** should be initiated at the time of surgery and typically continued for **at least 5 years** post-splenectomy, due to the lifelong increased risk of overwhelming post-splenectomy infection (OPSI) by encapsulated bacteria.
*Vaccinate: at the time of surgery; Penicillin: at time of surgery for 5 years*
- Vaccinating at the time of surgery does not allow enough time for the **immune system to mount an effective response** before the spleen's protective function is lost, leaving the patient vulnerable.
- While penicillin prophylaxis for 5 years is appropriate, the timing of vaccination is suboptimal.
*Vaccinate: 2 weeks prior to surgery; Penicillin: at time of surgery for an indefinite course*
- **Vaccinating 2 weeks prior to surgery** is the correct timing for optimal immune response.
- However, **indefinite penicillin prophylaxis** is usually reserved for patients with recurrent infections or other high-risk factors; a 5-year course is typically recommended for most adults after splenectomy.
*Vaccinate: 2 weeks prior to surgery; Penicillin: 2 weeks prior to surgery for an indefinite course*
- While **vaccinating 2 weeks prior to surgery** is correct, starting penicillin prophylaxis before surgery is generally not necessary unless there is an active infection.
- An **indefinite course of penicillin** is not the standard recommendation for all adult splenectomy patients; a 5-year course is more common.
*Vaccinate: at the time of surgery; Penicillin: 2 weeks prior to surgery for an indefinite course*
- **Vaccinating at the time of surgery** does not provide adequate time for the development of protective immunity, making it an incorrect approach.
- Starting **penicillin prophylaxis 2 weeks prior to surgery** is not standard practice, and an indefinite course is typically not recommended unless specific risk factors are present.
Special population considerations US Medical PG Question 9: A 3-month-old African American boy presents to his pediatrician’s office for his routine well visit. He was born full-term from an uncomplicated vaginal delivery. He is exclusively breastfeeding and not receiving any medications or supplements. Today, his parents report no issues or concerns with their child. He is lifting his head for brief periods and smiling. He has received only 2 hepatitis B vaccines. Which of the following is the correct advice for this patient’s parents?
- A. He should be sleeping more.
- B. He should have his serum lead level checked to screen for lead intoxication.
- C. He should start vitamin D supplementation. (Correct Answer)
- D. He should start rice cereal.
- E. He needs a 3rd hepatitis B vaccine.
Special population considerations Explanation: ***He should start vitamin D supplementation.***
- **Exclusively breastfed** infants, regardless of maternal vitamin D intake, require **vitamin D supplementation** due to insufficient amounts in breast milk.
- The recommended daily dose is **400 IU** starting from the first few days of life, to prevent **rickets** and promote bone health.
- **African American infants** have an additional risk factor due to increased skin melanin content, which reduces cutaneous vitamin D synthesis from sunlight exposure.
*He should be sleeping more.*
- A 3-month-old infant typically sleeps between **14-17 hours per day**, with **waking periods to feed** and interact.
- The case description does not indicate any concerns with the child's sleep patterns, and **developmental milestones** like lifting his head and smiling are being met.
*He should have his serum lead level checked to screen for lead intoxication.*
- **Lead screening** is not routinely recommended for all infants unless specific **risk factors** are present, such as living in an older home with lead paint, or having siblings with elevated lead levels.
- There are no reported risk factors for lead exposure in this patient's history.
*He should start rice cereal.*
- Introduction of solid foods, such as rice cereal, is typically recommended around **6 months of age**, when the infant shows signs of **developmental readiness**.
- These signs include **head control**, sitting with support, and showing interest in food.
*He needs a 3rd hepatitis B vaccine.*
- The **third dose of the hepatitis B vaccine** is typically administered between **6 and 18 months of age**.
- At 3 months old, the infant is not yet due for his third dose.
Special population considerations US Medical PG Question 10: Five weeks after delivery, a 1350-g (3-lb 0-oz) male newborn has respiratory distress. He was born at 26 weeks' gestation. He required intubation and mechanical ventilation for a month following delivery and has been on noninvasive pressure ventilation for 5 days. His temperature is 36.8°C (98.2°F), pulse is 148/min, respirations are 63/min, and blood pressure is 60/32 mm Hg. Pulse oximetry on 40% oxygen shows an oxygen saturation of 91%. Examination shows moderate intercostal and subcostal retractions. Scattered crackles are heard in the thorax. An x-ray of the chest shows diffuse granular densities and basal atelectasis. Which of the following is the most likely diagnosis?
- A. Bronchopulmonary dysplasia (Correct Answer)
- B. Tracheomalacia
- C. Bronchiolitis obliterans
- D. Interstitial emphysema
- E. Pneumonia
Special population considerations Explanation: ***Bronchopulmonary dysplasia***
- The presentation of a premature infant (26 weeks' gestation) with persistent respiratory distress requiring prolonged mechanical ventilation and oxygen, along with characteristic chest X-ray findings (diffuse granular densities and basal atelectasis), is highly indicative of **bronchopulmonary dysplasia (BPD)**.
- BPD is a chronic lung disease of prematurity defined by the need for supplemental oxygen and/or positive pressure ventilation for at least 28 days after birth, with severity classified at 36 weeks postmenstrual age (or discharge if earlier).
- The pathophysiology involves ventilator-induced injury, oxygen toxicity, and inflammation in the developing lung, leading to impaired alveolarization and abnormal vascular development.
*Tracheomalacia*
- While **tracheomalacia** can cause respiratory symptoms, it typically presents with expiratory stridor, a characteristic "barking" cough, or wheezing that may improve with neck extension or prone positioning.
- It is a structural abnormality of the trachea involving weakness of the tracheal wall, and would not typically manifest with diffuse granular densities or basal atelectasis on chest X-ray in this context.
*Bronchiolitis obliterans*
- **Bronchiolitis obliterans** is irreversible obstruction of the small airways, often occurring after severe viral infections (especially adenovirus or RSV), lung transplantation, or toxic inhalational injury.
- While it can occur in neonates post-ventilation, it is less common in this specific context and would typically present with more severe obstructive findings, hyperinflation, and air trapping on imaging rather than chronic diffuse granular densities and atelectasis.
*Interstitial emphysema*
- **Pulmonary interstitial emphysema** usually occurs acutely in the first days to weeks of mechanical ventilation, characterized by air dissecting into the lung interstitium and perivascular spaces.
- While it can be a complication that contributes to the development of BPD, the persistent nature of respiratory distress five weeks post-delivery, along with diffuse granular densities and chronic radiographic changes, points toward the established chronic lung disease of BPD rather than acute interstitial emphysema.
*Pneumonia*
- Neonatal **pneumonia** would typically present with acute onset or worsening of respiratory distress, temperature instability, and signs of systemic infection.
- While a chest X-ray might show infiltrates or consolidations, the chronic progressive course over 5 weeks, history of extreme prematurity, and prolonged ventilation make BPD a more fitting diagnosis than acute pneumonia in this clinical scenario.
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