A 48-hour-old newborn presents in respiratory distress. He is gasping for breath in the neonatal intensive care unit (NICU) and has had a fever for the past 2 days with a temperature ranging between 37.2°C (99.0°F) and 38.6°C (101.5°F). He also has not been feeding well and seems to be lethargic. The patient was delivered normally at 36 weeks of gestation. His mother had a premature rupture of membranes, which occurred with her last pregnancy, as well. No history of infection during pregnancy. On physical examination, a bulging anterior fontanelle is noticed, along with tensing of the extensor muscles. A lumbar puncture is performed, and CSF analysis is pending. Which of the following would be the best course of treatment in this patient?
Q52
A 64-hour-old baby girl is being evaluated for discharge. She was born by forceps-assisted vaginal delivery at 39 weeks gestation. The mother has no chronic medical conditions and attended all her prenatal visits. The mother’s blood type is A+. On day 1, the patient was noted to have a scalp laceration. Breastfeeding was difficult at first but quickly improved upon nurse assistance. The patient has had adequate wet diapers since birth. Upon physical examination, the resident notes the infant has scleral icterus and jaundiced skin. The scalp laceration noted on day 1 is intact without fluctuance or surrounding erythema. When the infant is slightly lifted from the bed and released, she spread out her arms, pulls them in, and exhibits a strong cry. Labs are drawn as shown below:
Blood type: AB-
Total bilirubin 8.7 mg/dL
Direct bilirubin 0.5 mg/dL
Six hours later, repeat total bilirubin is 8.3 mg/dL. Which of the following is the next best step in the management of the baby’s condition?
Q53
A 2-month-old boy is brought to the pediatrician for a routine check-up. His mother says he is feeding well and has no concerns. He is at the 85th percentile for height and 82nd percentile for weight. Immunizations are up-to-date. Results of serum hepatitis B surface antibody (anti-HBs) testing are positive. Which of the following best explains this patient's hepatitis B virus status?
Q54
A 9-year-old girl presents to the emergency department with a fever and a change in her behavior. She presented with similar symptoms 6 weeks ago and was treated for an Escherichia coli infection. She also was treated for a urinary tract infection 10 weeks ago. Her mother says that last night her daughter felt ill and her condition has been worsening. Her daughter experienced a severe headache and had a stiff neck. This morning she was minimally responsive, vomited several times, and produced a small amount of dark cloudy urine. The patient was born at 39 weeks and met all her developmental milestones. She is currently up to date on her vaccinations. Her temperature is 99.5°F (37.5°C), blood pressure is 60/35 mmHg, pulse is 190/min, respirations are 33/min, and oxygen saturation is 98% on room air. The patient is started on intravenous fluids, vasopressors, and broad-spectrum antibiotics. Which of the following is the best underlying explanation for this patient's presentation?
Q55
A 5-day-old male newborn is brought to the physician by his mother for the evaluation of progressive yellowing of his skin for 2 days. The mother reports that the yellowing started on the face and on the forehead before affecting the trunk and the limbs. She states that she breastfeeds every 2–3 hours and that the newborn feeds well. He has not vomited and there have been no changes in his bowel habits or urination. The patient was born at 38 weeks' gestation via vaginal delivery and has been healthy. His newborn screening was normal. His vital signs are within normal limits. Physical examination shows scleral icterus and widespread jaundice. The remainder of the examination shows no abnormalities. Serum studies show:
Bilirubin
Total 8 mg/dL
Direct 0.5 mg/dL
AST 16 U/L
ALT 16 U/L
Which of the following is the most appropriate next step in management?
Q56
A 16-day-old male newborn is brought to the emergency department because of fever and poor feeding for 2 days. He became very fussy the previous evening and cried for most of the night. He was born at 36 weeks' gestation and weighed 2430 g (5 lb 3 oz). The pregnancy and delivery were uncomplicated. The mother does not recall any sick contacts at home. He currently weighs 2776 g (6 lb 2 oz). He appears irritable. His temperature is 38.6°C (101.5°F), pulse is 180/min, and blood pressure is 82/51 mm Hg. Examination shows scleral icterus. He becomes more agitated when picked up. There is full range of motion of his neck and extremities. The anterior fontanelle feels soft and flat. Neurologic examination shows no abnormalities. Blood cultures are drawn and fluid resuscitation is initiated. A urinalysis obtained by catheterization shows no abnormalities. Which of the following is the most appropriate next step in diagnosis?
Q57
A 1-month-old boy is brought to the emergency department by his parents for recent episodes of non-bilious projectile vomiting and refusal to eat. The boy had no problem with passing meconium or eating at birth; he only started having these episodes at 3 weeks old. Further history reveals that the patient is a first born male and that the boy’s mother was treated with erythromycin for an infection late in the third trimester. Physical exam reveals a palpable mass in the epigastrum. Which of the following mechanisms is likely responsible for this patient’s disorder?
Q58
A 4390-g (9-lb 11-oz) male newborn is delivered at term to a 28-year-old primigravid woman. Pregnancy was complicated by gestational diabetes mellitus. Labor was prolonged by the impaction of the fetal shoulder and required hyperabduction of the left upper extremity. Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. Vital signs are within normal limits. Active movement of the left upper extremity is reduced. Further evaluation of this newborn is most likely to show which of the following?
Q59
Two hours after a 2280-g male newborn is born at 38 weeks' gestation to a 22-year-old primigravid woman, he has 2 episodes of vomiting and jitteriness. The mother has noticed that the baby is not feeding adequately. She received adequate prenatal care and admits to smoking one pack of cigarettes daily while pregnant. His temperature is 36.3°C (97.3°F), pulse is 171/min and respirations are 60/min. Pulse oximetry on room air shows an oxygen saturation of 92%. Examination shows pale extremities. There is facial plethora. Capillary refill time is 3 seconds. Laboratory studies show:
Hematocrit 70%
Leukocyte count 7800/mm3
Platelet count 220,000/mm3
Serum
Glucose 38 mg/dL
Calcium 8.3 mg/dL
Which of the following is the most likely cause of these findings?
Q60
A 10-day-old male infant is brought to the emergency room for abdominal distension for the past day. His mother reports that he has been refusing feeds for about 1 day and appears more lethargic than usual. While changing his diaper today, she noticed that the baby felt warm. He has about 1-2 wet diapers a day and has 1-2 seedy stools a day. The mother reports an uncomplicated vaginal delivery. His past medical history is significant for moderate respiratory distress following birth that has since resolved. His temperature is 101°F (38.3°C), blood pressure is 98/69 mmHg, pulse is 174/min, respirations are 47/min, and oxygen saturation is 99% on room air. A physical examination demonstrates a baby in moderate distress with abdominal distension. What is the best initial step in the management of this patient?
Neonatal infections US Medical PG Practice Questions and MCQs
Question 51: A 48-hour-old newborn presents in respiratory distress. He is gasping for breath in the neonatal intensive care unit (NICU) and has had a fever for the past 2 days with a temperature ranging between 37.2°C (99.0°F) and 38.6°C (101.5°F). He also has not been feeding well and seems to be lethargic. The patient was delivered normally at 36 weeks of gestation. His mother had a premature rupture of membranes, which occurred with her last pregnancy, as well. No history of infection during pregnancy. On physical examination, a bulging anterior fontanelle is noticed, along with tensing of the extensor muscles. A lumbar puncture is performed, and CSF analysis is pending. Which of the following would be the best course of treatment in this patient?
A. Ampicillin and acyclovir
B. Ampicillin and sulbactam
C. Ampicillin and cefotaxime
D. Ampicillin and gentamicin (Correct Answer)
E. Ampicillin and ticarcillin
Explanation: ***Ampicillin and gentamicin***
- This combination provides broad-spectrum coverage against common neonatal pathogens causing **meningitis**, including **Group B Streptococcus (GBS)**, **E. coli**, and *Listeria monocytogenes*.
- **Ampicillin** covers *Listeria* and sensitive *GBS*, while **gentamicin**, an aminoglycoside, effectively covers **Gram-negative bacteria** like *E. coli* and acts synergistically with ampicillin against gram-positive organisms.
- This is a **standard first-line empiric regimen** for neonatal bacterial meningitis in many institutions.
*Incorrect: Ampicillin and acyclovir*
- **Acyclovir** is an antiviral agent used for **herpes simplex virus (HSV)** infections, which can cause neonatal encephalitis and disseminated disease.
- While HSV should be considered in neonates with CNS symptoms, **bacterial meningitis is more common** and requires immediate broad-spectrum antibacterial coverage.
- Acyclovir would be added if HSV is highly suspected (maternal vesicular lesions, seizures, CSF findings suggestive of viral infection) or confirmed, but is not part of initial empiric antibacterial therapy.
*Incorrect: Ampicillin and sulbactam*
- **Sulbactam** is a beta-lactamase inhibitor combined with ampicillin to extend coverage against **beta-lactamase-producing bacteria**.
- This combination does not provide adequate coverage for the most common neonatal meningitis pathogens, particularly **Gram-negative organisms** like *E. coli*, which require an aminoglycoside or third-generation cephalosporin.
- Not a standard regimen for neonatal CNS infections.
*Incorrect: Ampicillin and cefotaxime*
- **Cefotaxime**, a third-generation cephalosporin, combined with ampicillin is an **alternative first-line regimen** for neonatal bacterial meningitis and is actually **preferred in many institutions**.
- Advantages include: **better CSF penetration** than gentamicin, avoidance of aminoglycoside toxicity (nephrotoxicity, ototoxicity), and excellent Gram-negative coverage.
- Both ampicillin + gentamicin and ampicillin + cefotaxime are acceptable; the choice depends on institutional protocols and clinical factors. In this question, ampicillin + gentamicin is the **best answer** as it represents the traditional standard, but ampicillin + cefotaxime would also be clinically appropriate.
*Incorrect: Ampicillin and ticarcillin*
- **Ticarcillin** is an extended-spectrum penicillin with activity against *Pseudomonas aeruginosa* and some other Gram-negative bacteria.
- This is **not a standard regimen** for neonatal bacterial meningitis, as it does not offer the comprehensive coverage or synergistic benefits needed for common neonatal pathogens.
- Ticarcillin is typically used in specific clinical contexts (e.g., cystic fibrosis, hospital-acquired infections) and is not part of empiric neonatal meningitis protocols.
Question 52: A 64-hour-old baby girl is being evaluated for discharge. She was born by forceps-assisted vaginal delivery at 39 weeks gestation. The mother has no chronic medical conditions and attended all her prenatal visits. The mother’s blood type is A+. On day 1, the patient was noted to have a scalp laceration. Breastfeeding was difficult at first but quickly improved upon nurse assistance. The patient has had adequate wet diapers since birth. Upon physical examination, the resident notes the infant has scleral icterus and jaundiced skin. The scalp laceration noted on day 1 is intact without fluctuance or surrounding erythema. When the infant is slightly lifted from the bed and released, she spread out her arms, pulls them in, and exhibits a strong cry. Labs are drawn as shown below:
Blood type: AB-
Total bilirubin 8.7 mg/dL
Direct bilirubin 0.5 mg/dL
Six hours later, repeat total bilirubin is 8.3 mg/dL. Which of the following is the next best step in the management of the baby’s condition?
A. Phototherapy
B. Exchange transfusion
C. Observation (Correct Answer)
D. Switch to baby formula
E. Coombs test
Explanation: ***Observation***
- The baby is a healthy, full-term infant with a total bilirubin level of 8.7 mg/dL at 64 hours of life, which is well below the phototherapy threshold for a low-risk infant (approximately 15 mg/dL at this age based on AAP nomograms)
- **Most importantly**, the bilirubin level has **decreased** over 6 hours (from 8.7 to 8.3 mg/dL), indicating that the jaundice is likely physiological and resolving spontaneously
- The predominantly unconjugated hyperbilirubinemia (direct bilirubin only 0.5 mg/dL) with declining trend supports observation as the appropriate management
*Phototherapy*
- Phototherapy is indicated for higher bilirubin levels, typically above 12-15 mg/dL at 60-72 hours for a healthy, full-term infant without risk factors
- The current bilirubin level of 8.7 mg/dL is too low to warrant phototherapy, and the **declining trend** further supports conservative management
*Exchange transfusion*
- Exchange transfusion is reserved for severe hyperbilirubinemia, usually with total bilirubin levels exceeding 20-25 mg/dL in term infants, or in cases of acute bilirubin encephalopathy
- This baby's bilirubin level is significantly below this threshold, there are no signs of acute encephalopathy, and the infant demonstrates normal neurologic findings (intact Moro reflex)
*Switch to baby formula*
- While breastfeeding jaundice can contribute to elevated bilirubin levels, this infant's bilirubin is not critically high and is actually decreasing
- Breastfeeding has improved with nursing assistance and the infant has adequate wet diapers, indicating successful feeding
- Interrupting breastfeeding is not indicated when bilirubin levels are this low and trending downward
*Coombs test*
- A Coombs test (direct antiglobulin test) helps identify isoimmune hemolytic disease such as ABO or Rh incompatibility
- While there is potential ABO incompatibility (mother A+, baby AB-), the bilirubin level is not critically high, is declining, and is well below treatment thresholds
- Additional testing to determine etiology is not necessary when the jaundice is mild, improving, and not requiring intervention
Question 53: A 2-month-old boy is brought to the pediatrician for a routine check-up. His mother says he is feeding well and has no concerns. He is at the 85th percentile for height and 82nd percentile for weight. Immunizations are up-to-date. Results of serum hepatitis B surface antibody (anti-HBs) testing are positive. Which of the following best explains this patient's hepatitis B virus status?
A. Active immunity from vaccination (Correct Answer)
B. Window period
C. Vaccination reaction
D. Spontaneous recovery
E. Chronic infection
Explanation: ***Active immunity from vaccination***
- A 2-month-old infant with **up-to-date immunizations** and positive **anti-HBs (hepatitis B surface antibody)** has developed **active immunity** from the **hepatitis B vaccine series**.
- The standard immunization schedule includes hepatitis B vaccine at **birth and 1-2 months**, with a third dose at 6-18 months.
- Positive anti-HBs indicates a **protective immune response** to vaccination, which provides **long-lasting immunity**.
*Passive immunity*
- **Passive immunity** involves transfer of maternal **IgG antibodies** across the placenta, providing temporary protection.
- However, in a 2-month-old with **up-to-date immunizations**, positive anti-HBs is best explained by **active immunization**, not passive transfer.
- Maternal antibodies would not be documented as part of routine "serum testing" and would wane over time without providing lasting immunity.
*Window period*
- The **window period** refers to the time after acute infection when **HBsAg becomes undetectable** and **anti-HBs has not yet appeared**.
- During this phase, **anti-HBc IgM** (and total anti-HBc) would be the only detectable markers.
- The presence of positive **anti-HBs** rules out the window period.
*Chronic infection*
- **Chronic hepatitis B infection** is characterized by persistent presence of **HBsAg (hepatitis B surface antigen)** for more than six months.
- The presence of **anti-HBs** indicates **immunity**, not infection, and rules out chronic hepatitis B.
*Spontaneous recovery*
- **Spontaneous recovery** from acute hepatitis B would show **anti-HBs** and **anti-HBc**, with negative **HBsAg**.
- This is extremely unlikely in a healthy 2-month-old with no history of infection.
- The vaccination history provides a much simpler explanation for positive anti-HBs.
Question 54: A 9-year-old girl presents to the emergency department with a fever and a change in her behavior. She presented with similar symptoms 6 weeks ago and was treated for an Escherichia coli infection. She also was treated for a urinary tract infection 10 weeks ago. Her mother says that last night her daughter felt ill and her condition has been worsening. Her daughter experienced a severe headache and had a stiff neck. This morning she was minimally responsive, vomited several times, and produced a small amount of dark cloudy urine. The patient was born at 39 weeks and met all her developmental milestones. She is currently up to date on her vaccinations. Her temperature is 99.5°F (37.5°C), blood pressure is 60/35 mmHg, pulse is 190/min, respirations are 33/min, and oxygen saturation is 98% on room air. The patient is started on intravenous fluids, vasopressors, and broad-spectrum antibiotics. Which of the following is the best underlying explanation for this patient's presentation?
A. Urinary tract infection
B. Meningitis
C. Gastroenteritis
D. Sepsis (Correct Answer)
E. Acute pyelonephritis
Explanation: ***Sepsis***
- The patient exhibits a constellation of symptoms including fever, altered mental status, **hypotension (60/35 mmHg)**, **tachycardia (190/min)**, and tachypnea, which are classic signs of **septic shock**.
- A history of recent *E. coli* infection and urinary tract infections further supports the diagnosis, as these can be sources of bacterial dissemination leading to sepsis.
*Urinary tract infection*
- While the patient has a history of UTIs and dark, cloudy urine, a UTI alone would not explain the **severe hemodynamic instability (shock)** and altered mentation observed.
- UTIs are a potential *source* of infection but do not fully encompass the systemic, life-threatening symptoms presented.
*Meningitis*
- Symptoms like headache, stiff neck, and altered responsiveness are consistent with meningitis, but this diagnosis does not account for the profound **hypotension** and **tachycardia** indicative of systemic circulatory collapse.
- Meningitis could be a complication of sepsis, but sepsis is the overarching and more critical condition explaining the patient's current instability.
*Gastroenteritis*
- Vomiting is present, but the lack of diarrhea and the presence of severe neurological and cardiovascular signs make gastroenteritis an unlikely primary diagnosis.
- Gastroenteritis would typically cause dehydration, but not the specific constellation of septic shock signs seen here.
*Acute pyelonephritis*
- This condition involves kidney infection, which could cause fever and dark cloudy urine, but it typically doesn't directly lead to the profound **hypotension and altered mental status** without progression to sepsis.
- Pyelonephritis is a localized infection that can *precede* sepsis, but it doesn't explain the full systemic inflammatory response observed.
Question 55: A 5-day-old male newborn is brought to the physician by his mother for the evaluation of progressive yellowing of his skin for 2 days. The mother reports that the yellowing started on the face and on the forehead before affecting the trunk and the limbs. She states that she breastfeeds every 2–3 hours and that the newborn feeds well. He has not vomited and there have been no changes in his bowel habits or urination. The patient was born at 38 weeks' gestation via vaginal delivery and has been healthy. His newborn screening was normal. His vital signs are within normal limits. Physical examination shows scleral icterus and widespread jaundice. The remainder of the examination shows no abnormalities. Serum studies show:
Bilirubin
Total 8 mg/dL
Direct 0.5 mg/dL
AST 16 U/L
ALT 16 U/L
Which of the following is the most appropriate next step in management?
A. Abdominal sonography
B. Exchange transfusion
C. Intravenous immunoglobulin
D. Phototherapy
E. Reassurance (Correct Answer)
Explanation: ***Reassurance***
- The newborn's age, normal physical examination findings, stable vital signs, and isolated **unconjugated hyperbilirubinemia** (total 8 mg/dL, direct 0.5 mg/dL) are consistent with **physiologic jaundice of the newborn**.
- Given that the **bilirubin level is well below the threshold for intervention** in a healthy term infant (typically requiring phototherapy around 15 mg/dL at 5 days old), reassurance for the mother and continued monitoring are appropriate.
*Abdominal sonography*
- This imaging study would be considered if there were suspicion of an **obstructive cause** for jaundice, such as biliary atresia, which is typically associated with **conjugated hyperbilirubinemia** and other signs like pale stools.
- The patient's **direct bilirubin is normal**, making an obstructive pathology less likely.
*Exchange transfusion*
- This is an emergent intervention reserved for cases of **severe hyperbilirubinemia** (often >25 mg/dL) at risk of **kernicterus**, or when there are signs of acute bilirubin encephalopathy.
- The current bilirubin level of 8 mg/dL is **far below the threshold** for exchange transfusion.
*Intravenous immunoglobulin*
- IVIG is used in cases of **severe hemolytic disease of the newborn** caused by ABO or Rh incompatibility to reduce bilirubin levels by blocking antibody-mediated hemolysis.
- There is **no indication of hemolytic disease** in this case (e.g., no mention of blood group incompatibility, anemia, or rapid rise in bilirubin).
*Phototherapy*
- Phototherapy is indicated when bilirubin levels reach specific **age- and risk-factor-dependent thresholds** to prevent kernicterus.
- For a healthy 5-day-old term infant, the **phototherapy threshold is typically around 15 mg/dL**, which is significantly higher than this patient's 8 mg/dL.
Question 56: A 16-day-old male newborn is brought to the emergency department because of fever and poor feeding for 2 days. He became very fussy the previous evening and cried for most of the night. He was born at 36 weeks' gestation and weighed 2430 g (5 lb 3 oz). The pregnancy and delivery were uncomplicated. The mother does not recall any sick contacts at home. He currently weighs 2776 g (6 lb 2 oz). He appears irritable. His temperature is 38.6°C (101.5°F), pulse is 180/min, and blood pressure is 82/51 mm Hg. Examination shows scleral icterus. He becomes more agitated when picked up. There is full range of motion of his neck and extremities. The anterior fontanelle feels soft and flat. Neurologic examination shows no abnormalities. Blood cultures are drawn and fluid resuscitation is initiated. A urinalysis obtained by catheterization shows no abnormalities. Which of the following is the most appropriate next step in diagnosis?
A. Lumbar puncture (Correct Answer)
B. Urine culture
C. CT scan of the head
D. Reassurance
E. MRI of the head
Explanation: ***Lumbar puncture***
- A **febrile neonate** (less than 28 days old) with irritability and poor feeding is considered to have **sepsis until proven otherwise**, requiring a complete sepsis workup.
- A **lumbar puncture** is crucial to rule out **meningitis**, as neck stiffness might be absent in neonates, and the clinical presentation can be subtle but rapidly progressive.
- **Paradoxical irritability** (increased agitation when handled) is a classic sign of meningitis in neonates.
- LP must be performed **before starting empiric antibiotics** to obtain diagnostic CSF, making it the priority next diagnostic step.
*Urine culture*
- While a **urine culture** is part of a complete sepsis workup in a neonate and was likely sent when the catheterized urinalysis was obtained, it is not the most urgent **next diagnostic step**.
- The question asks for the next step in **diagnosis**, and **lumbar puncture takes priority** because it must be done before antibiotics are started and addresses the most immediately life-threatening condition (meningitis).
- Urine culture results take 24-48 hours, whereas CSF analysis can provide immediate information about cell counts and Gram stain.
*CT scan of the head*
- A **CT scan of the head** is generally not the initial diagnostic step for suspected neonatal sepsis or meningitis due to radiation exposure and limited sensitivity for early inflammatory changes.
- While it may be used to look for complications such as **abscesses** or **hydrocephalus**, these are usually considered after a lumbar puncture, if indicated by clinical deterioration or abnormal CSF findings.
- CT is not required before LP in neonates with soft fontanelles and no focal neurologic deficits.
*Reassurance*
- Given the newborn's **fever (38.6°C)**, **irritability**, **poor feeding**, and **tachycardia (180/min)**, reassurance is entirely inappropriate and could lead to significant harm.
- These are red flag symptoms in a neonate that warrant immediate and aggressive medical evaluation and intervention.
*MRI of the head*
- An **MRI of the head** is a more detailed neuroimaging study but is **time-consuming** and requires **sedation**, making it impractical as an initial emergency diagnostic tool for a febrile neonate.
- It would be considered later for specific neurological concerns or complications, not as the first step to rule out **meningitis** in an acutely ill infant.
Question 57: A 1-month-old boy is brought to the emergency department by his parents for recent episodes of non-bilious projectile vomiting and refusal to eat. The boy had no problem with passing meconium or eating at birth; he only started having these episodes at 3 weeks old. Further history reveals that the patient is a first born male and that the boy’s mother was treated with erythromycin for an infection late in the third trimester. Physical exam reveals a palpable mass in the epigastrum. Which of the following mechanisms is likely responsible for this patient’s disorder?
A. Pancreatic fusion abnormality
B. Defect of lumen recanalization
C. Neural crest cell migration failure
D. Intestinal vascular accident
E. Hypertrophy of smooth muscle (Correct Answer)
Explanation: ***Hypertrophy of smooth muscle***
- The clinical presentation of **non-bilious projectile vomiting** in a 1-month-old infant, especially a first-born male, strongly suggests **pyloric stenosis**. The palpable **epigastric mass** ("olive") on examination further supports this diagnosis.
- The mechanism underlying pyloric stenosis is **hypertrophy and hyperplasia of the pyloric sphincter muscle**, leading to gastric outlet obstruction. Maternal use of **erythromycin** in late pregnancy is a known risk factor.
*Pancreatic fusion abnormality*
- Pancreatic fusion abnormalities, such as **annular pancreas**, can cause duodenal obstruction and bilious vomiting, but this typically presents earlier and causes **bilious vomiting**, not non-bilious.
- An annular pancreas would not present with a palpable epigastric mass consistent with a hypertrophied pylorus.
*Defect of lumen recanalization*
- A defect in lumen recanalization can lead to conditions like **duodenal atresia**, which typically presents with **bilious vomiting** and neonatal onset.
- Duodenal atresia is characterized by a "double bubble" sign on imaging, and would not involve a palpable epigastric mass.
*Neural crest cell migration failure*
- Failure of neural crest cell migration is the mechanism behind **Hirschsprung disease**, which causes **functional intestinal obstruction** and typically presents with delayed meconium passage and constipation, not projectile vomiting.
- The symptoms described do not align with the typical presentation of Hirschsprung disease.
*Intestinal vascular accident*
- An intestinal vascular accident could lead to conditions like **intestinal atresia** or **volvulus**, which typically cause **bilious vomiting**, and often present with abdominal distension and signs of ischemia.
- This mechanism would not explain the gradual onset of non-bilious vomiting and a palpable pyloric mass seen in this patient.
Question 58: A 4390-g (9-lb 11-oz) male newborn is delivered at term to a 28-year-old primigravid woman. Pregnancy was complicated by gestational diabetes mellitus. Labor was prolonged by the impaction of the fetal shoulder and required hyperabduction of the left upper extremity. Apgar scores were 7 and 8 at 1 and 5 minutes, respectively. Vital signs are within normal limits. Active movement of the left upper extremity is reduced. Further evaluation of this newborn is most likely to show which of the following?
A. Lower back mass
B. Decreased movement of unilateral rib cage (Correct Answer)
C. Absent nasolabial fold
D. Generalized hypotonia
E. Absent unilateral grasp reflex
Explanation: ***Decreased movement of unilateral rib cage***
- The history of **shoulder dystocia** and **hyperabduction of the left upper extremity**, combined with **reduced active movement** of that limb, strongly suggests a **brachial plexus injury**, specifically **Erb-Duchenne palsy (Erb's palsy)**.
- Erb's palsy results from injury to the **upper brachial plexus (C5-C6, sometimes C7)** and classically presents with the affected arm in the **"waiter's tip" position** with weakness in shoulder abduction and elbow flexion.
- **Phrenic nerve involvement** can occur with upper brachial plexus injuries, as the phrenic nerve arises from **C3-C5 nerve roots**. This leads to **ipsilateral diaphragmatic paralysis**, manifesting as **decreased movement of the unilateral rib cage** on the affected side.
- Additional findings may include an **absent or diminished Moro reflex** on the affected side.
*Absent unilateral grasp reflex*
- The **grasp reflex** is mediated by the **lower brachial plexus (C8-T1)**, which is typically **preserved in Erb's palsy**.
- Injury to C8-T1 causes **Klumpke's palsy**, which is much rarer and presents with hand weakness and an absent grasp reflex, but this typically does not result from shoulder dystocia.
- In this case, the mechanism of injury (shoulder dystocia with hyperabduction) affects the upper plexus, not the lower plexus.
*Lower back mass*
- A lower back mass, such as a **meningocele** or **myelomeningocele**, is associated with **neural tube defects**, which are not indicated by the clinical presentation of shoulder dystocia and upper extremity weakness.
- These conditions would be identified prenatally or immediately at birth and do not result from birth trauma.
*Absent nasolabial fold*
- An absent nasolabial fold indicates **facial nerve palsy (cranial nerve VII)**, which is typically caused by direct trauma to the face during delivery (e.g., from forceps) or compression against the maternal pelvis.
- This finding is unrelated to shoulder dystocia or brachial plexus injury affecting the upper extremity.
*Generalized hypotonia*
- **Generalized hypotonia** suggests a systemic issue such as **hypoxic-ischemic encephalopathy**, severe sepsis, metabolic disorder, or genetic condition.
- The normal Apgar scores (7 and 8) and vital signs, along with the **localized weakness** to one upper extremity, make generalized hypotonia unlikely.
Question 59: Two hours after a 2280-g male newborn is born at 38 weeks' gestation to a 22-year-old primigravid woman, he has 2 episodes of vomiting and jitteriness. The mother has noticed that the baby is not feeding adequately. She received adequate prenatal care and admits to smoking one pack of cigarettes daily while pregnant. His temperature is 36.3°C (97.3°F), pulse is 171/min and respirations are 60/min. Pulse oximetry on room air shows an oxygen saturation of 92%. Examination shows pale extremities. There is facial plethora. Capillary refill time is 3 seconds. Laboratory studies show:
Hematocrit 70%
Leukocyte count 7800/mm3
Platelet count 220,000/mm3
Serum
Glucose 38 mg/dL
Calcium 8.3 mg/dL
Which of the following is the most likely cause of these findings?
A. Intrauterine hypoxia (Correct Answer)
B. Transient tachypnea of the newborn
C. Hyperinsulinism
D. Congenital heart disease
E. Intraventricular hemorrhage
Explanation: ***Intrauterine hypoxia***
- **Chronic intrauterine hypoxia** stimulates erythropoietin production, leading to **polycythemia** (Hct 70%) and **hyperviscosity**, which can cause poor feeding, vomiting, jitteriness, and circulatory disturbances like prolonged capillary refill and facial plethora.
- The mother's history of **smoking** during pregnancy is a significant risk factor for intrauterine hypoxia and **intrauterine growth restriction (IUGR)**, contributing to the newborn's small size for gestational age (2280g at 38 weeks).
*Transient tachypnea of the newborn*
- Characterized by **respiratory distress** due to delayed clearance of fetal lung fluid, presenting with tachypnea, grunting, and retractions.
- While this newborn has tachypnea (respirations 60/min), the primary symptoms point towards **hyperviscosity syndrome** and hypoglycemia, not primarily respiratory issues.
*Hyperinsulinism*
- This condition primarily causes **hypoglycemia** (glucose 38 mg/dL) due to excessive insulin production.
- However, it does not explain the presence of **polycythemia**, facial plethora, prolonged capillary refill, or the mother's smoking history.
*Congenital heart disease*
- Can cause symptoms like **cyanosis**, poor feeding, and tachypnea, and some forms could contribute to hypoxia.
- It does not directly explain the **polycythemia** or the mother's smoking history as a causal factor for all presenting signs.
*Intraventricular hemorrhage*
- Typically seen in **premature infants** and can cause neurological symptoms like lethargy, hypotonia, and seizures.
- While jitteriness can be a symptom, it does not account for the **polycythemia**, facial plethora, or improved feeding with interventions for hyperviscosity.
Question 60: A 10-day-old male infant is brought to the emergency room for abdominal distension for the past day. His mother reports that he has been refusing feeds for about 1 day and appears more lethargic than usual. While changing his diaper today, she noticed that the baby felt warm. He has about 1-2 wet diapers a day and has 1-2 seedy stools a day. The mother reports an uncomplicated vaginal delivery. His past medical history is significant for moderate respiratory distress following birth that has since resolved. His temperature is 101°F (38.3°C), blood pressure is 98/69 mmHg, pulse is 174/min, respirations are 47/min, and oxygen saturation is 99% on room air. A physical examination demonstrates a baby in moderate distress with abdominal distension. What is the best initial step in the management of this patient?
A. Radionuclide scan
B. Voiding cystourethrogram
C. Renal ultrasound
D. Urinary catheterization
E. Start IV fluids and antibiotics (Correct Answer)
Explanation: ***Start IV fluids and antibiotics***
- This infant presents with **fever**, **lethargy**, **abdominal distension**, and poor feeding in the setting of a history of respiratory distress, which is highly concerning for **sepsis** with possible **necrotizing enterocolitis (NEC)** or another serious bacterial infection.
- The infant is **ill-appearing and in moderate distress** - this requires **immediate empiric antibiotic therapy** and supportive care with **IV fluids** to stabilize the patient.
- While cultures (blood, urine, and possibly CSF) should be obtained, **antibiotics must NOT be delayed** in a toxic-appearing neonate. The standard approach is to obtain cultures quickly and start antibiotics immediately.
- **NEC** is a surgical emergency in neonates, especially those with risk factors like prematurity (suggested by the respiratory distress history), and requires urgent broad-spectrum antibiotics, bowel rest (NPO), and IV fluids.
*Urinary catheterization*
- While **urinary catheterization** is important to obtain a sterile urine specimen for culture in a febrile infant, it is **part of the workup**, not the "best initial step" when a child is this ill.
- Cultures should be obtained rapidly, but treatment should begin immediately - you do not delay life-saving antibiotics just to get a urine culture first.
- In this case, the primary concern is **abdominal pathology (NEC)** rather than isolated UTI.
*Radionuclide scan*
- A **radionuclide scan** (DMSA scan) is used to detect renal scarring after a confirmed UTI and has no role in the acute management of a septic neonate.
- This would provide no useful information for immediate diagnosis or treatment.
*Voiding cystourethrogram*
- A **voiding cystourethrogram (VCUG)** evaluates for **vesicoureteral reflux** and is performed weeks after a febrile UTI has been treated, not during acute presentation.
- This is completely inappropriate for an acutely ill neonate with abdominal distension.
*Renal ultrasound*
- A **renal ultrasound** assesses renal anatomy and structural abnormalities but does not diagnose acute infection and does not address the primary concern of abdominal distension.
- While it may be part of a later workup for febrile UTI, it is not the priority in a toxic-appearing infant who needs immediate stabilization and treatment.