الجمعة، 19 أكتوبر، 2012

MCQs In Neonatology

Q1 :

A 2-week-old infant presents to the emergency department with a 1-day history of decreased
feeding, pallor, diaphoresis, and increasing somnolence. He was born at term, and the delivery
was uncomplicated. On physical examination, his heart rate is 190 beats/min, his respiratory
rate is 80 breaths/min, his blood pressure is 50/30 mm Hg, and his extremities are cool and pale
with poor pulses. You place the infant on a cardiorespiratory monitor and begin your
assessment and management.

Of the following, the MOST appropriate pair of tests to consider in this child is

A. complete blood count and bone scan
B. electrocardiography and echocardiography
C. electroencephalography and head ultrasonography
D. lumbar puncture and head computed tomography scan
E. serum electrolytes and chest computed tomography scan

The Answer :

B

Explanation :

The child described in the vignette is in shock and has clinical signs and symptoms of
diminished systemic perfusion. His heart rate is elevated to increase cardiac output (cardiac
output = heart rate x stroke volume). Shock has several causes in the neonate, including
hypovolemia, sepsis, and metabolic and cardiogenic dysfunction. Differentiating these causes
upon presentation in the neonate can be difficult.

Although it is appropriate for the infant described in the vignette to receive empiric broadspectrum
antibiotics against the most likely infectious organisms in this age group, performing a
lumbar puncture may compromise the infant’s cardiorespiratory status further and is
contraindicated. Because the findings in this infant are most consistent with cardiogenic shock,

an electocardiogram and echocardiogram should be obtained as soon as possible. These tests
can be performed at the bedsides of even the most critically ill infants. 

There is no reason to perform computed tomography scan, bone scan, or electrocephalography in this infant. Although a complete blood count and electrolytes should be measured, it is unlikely that these test will aid
in the immediate management of the infant described in this vignette.

In the first few weeks after birth, cardiogenic shock often is due to cardiac anomalies.

Congenital heart lesions that may lead to such a dramatic presentation include those that require
ductal patency for the maintenance of systemic blood flow.

Among these are :

 critical aortic stenosis

 aortic coarctation

 interruption of the aortic arch

 hypoplastic left heart syndrome.

In each of these left heart obstructive lesions, persistence of the fetal shunting pattern through
the ductus arteriosus from the pulmonary artery to the aorta provides the necessary blood flow
to the aorta to maintain end-organ and cellular perfusion. 

As the ductus arteriosus begins to close in the hours and days after delivery, the volume of blood delivered to the systemic circulation diminishes in patients who have severe left heart obstruction. 

Although the ductus arteriosus closes by the fourth postnatal day in approximately 90% of neonates, in some infants, closure does not occur for several weeks. 

Therefore, left heart obstructive lesions should be considered in any neonate who presents with congestive failure and shock, and administration of prostaglandin E to establish or maintain ductal patency should be considered.

Head ultrasonography may be important in determining this child’s prognosis afterstabilization, but it cannot aid in diagnosis and acute management.


----------------------------------------------------------

Q2 :

You are evaluating an 8-week-old infant whose birthweight was 1,000 g and who was delivered
at 30 weeks’ gestation. He experienced early respiratory distress and sepsis, but now these
problems have resolved, and he recently progressed from parenteral nutrition to full enteral
feedings.

Of the following, the feeding that will provide the BEST mineral content to ensure healthy bone
development for this infant is

A. cow milk-based infant formula
B. human milk
C. premature formula
D. protein hydrolysate formula
E. soy protein-based formula


Answer :

C

Explanation :

The optimal source of nutrition for the infant in the vignette should provide sufficient energy
substrate (carbohydrate and lipid) and protein to facilitate growth and development as well as the
necessary minerals and vitamins to help make up for delayed bone mineralization. Term infant
cow milk-based formula lacks sufficient calories, protein, Ca++, P, and other trace minerals and
vitamins, as does unsupplemented human milk. Term formulas and human milk require
supplementation with a fortifier to meet these goals.

Formulas designed specifically for preterm infants contain higher caloric density; more
readily absorbed lipids; greater protein content; and enriched Ca++, P, and other minerals and
vitamins. They provide the best mineral content to ensure healthy bone development in VLBW
preterm infants and generally do so by the time the infant attains a postconceptive age of 44
weeks. Protein hydrolysate formulas and soy protein-based formulas deliver suboptimal energy,
protein, minerals, and vitamins to VLBW preterm infants and should be used only for a specific
indication for a limited period of time.


------------------------------

Q 3 :


A 4-week-old infant who was born at term without any complications ate well and gained weight for the first 3 weeks after birth. Over the last week, however, his mother reports that he appears hungry but fatigues with feeding and now takes twice as long to complete his feeding as he did 1 week ago. He also breathes fast during his feedings and stops frequently to "catch his breath." Of the following, the MOST likely explanation for the symptoms in this infant is

A. aspiration syndrome
B. congestive heart failure
C. gastroesophageal reflux disease
D. inborn error of metabolism
E. pneumonia

Answer :

B

The symptoms described for the child in the vignette are typical of progressive congestive heart failure (CHF).

The "hunger" described by the mother suggests that the problem results from the infant's inability to take enough calories for satiation and growth. Such so-called poor feeding is due to his inability to generate a prolonged suck while maintaining nasal breathing because of the tachypnea that is caused by pulmonary congestion. Thus, the infant seems to stop sucking and "catch his breath."

 Decreased caloric intake coupled with increased caloric expenditure caused by tachypnea and tachycardia makes it difficult for the infant to gain weight. Indeed, weight loss is common in infants who have CHF.

CHF is a clinical syndrome that reflects the inability of the myocardium to meet the metabolic requirements of the body, including those for growth.

 CHF results from excessive workload imposed on the cardiac muscle that usually is caused by the structural defects. The cardiac defects may impose an excessive volume load on the left ventricle (eg, large ventricular septal defect, atrioventricular septal defect), an excessive pressure load on the ventricle (eg, aortic stenosis), or a combination of volume and pressure load (eg, ventricular septal defect with coarctation).

 Less commonly, CHF may be caused by an intrinsic alteration in myocardial performance, which could result from an inflammatory or an infectious process that directly affects the myocardium and depresses its contractile function.

Aspiration syndrome typically is an acute event resulting from the passage of gastrointestinal contents (including food) into the lungs. The symptoms usually are acute and not associated with poor feeding in spite of hunger.

 Similarly, gastrointestinal reflux presents more acutely with signs of discomfort that might include arching during feedings.

 Pneumonia is associated with other signs of infection, including tachypnea when at rest, fever, or change in
behavior.

 Inborn errors of metabolism, although less common, are important to consider in the neonate and infant who is not feeding well. Most commonly, they are associated with symptoms that are present both at rest and during feeding as well as other systemic signs.

-----

Q4 :

You are examining a 3-week-old preterm infant who was born at 26 weeks’ gestation and is receiving continuous positive airway pressure (CPAP) respiratory support. He has had increasing episodes of apnea and bradycardia over the past 12 hours. On physical examination, his temperature is 37.0°C, heart rate is 150 beats/min, and respiratory rate is 50 breaths/min on CPAP pressure support of 6 mm Hg with an FiO2 0.35. The infant has a flat and soft anterior fontanelle, moist mucous membranes, normal heart and lung sounds, and benign findings on abdominal examination. His extremities are mildly warm, and his left knee is swollen without noticeable erythema. Range of motion of the left knee is mildly decreased compared with the right. A clean and dry dressing covers a peripherally inserted central venous catheter in the right arm. The white blood cell count is 9.0x103/mcL (9.0x109/L), with 55%polymorphonuclear leukocytes, 10% band forms, 30% lymphocytes, and 5% monocytes.
 Cerebrospinal fluid evaluation reveals 15 white blood cells/mm3 with 80% lymphocytes, 10% polymorphonuclear leukocytes, and 10% monocytes; protein of 70 mg/dL; and glucose of 60 mg/dL. Urinalysis yields normal results. Blood, cerebrospinal fluid, and urine specimens have been sent for cultures. A magnetic resonance imaging study reveals increased signal in the left knee. You order broad-spectrum intravenous antibiotics.

Of the following, the next BEST step is

A. arthrocentesis of the left knee
B. bone scan of the left knee
C. radiograph of the left knee
D. removal of the central venous catheter
E. ultrasonography of the left knee

Answer :

A


The preterm infant described in the vignette has hematogenously acquired infective osteoarthritis, most likely caused by Staphylococcus aureus. Arthrocentesis of the knee and cultures of fluid and bone would assist in establishing the diagnosis.

The unique neonatal anatomy allows spread of bacteria from the metaphyseal bone through the transphyseal vessels into the epiphysis and the adjacent joint.

Therefore, unlike most infections in older children, neonatal disease involves both the bone and joint contiguously.

The most common clinical presentation of infective osteoarthritis is an occult bacteremia that
leads to inoculation of bone, and multiple sites can be involved in up to 50% of cases.

The femur and tibia are the most commonly infected bones (80%), and adjacent arthritis is common.

 The clinical findings, especially in preterm infants, can be subtle.

Infants may be irritable, with mild swelling of the affected area and decreased movement of the limb.

Marked limb swelling and erythema may be absent.

The infants can be afebrile and have normal vital signs.

 Serum inflammatory markers (C-reactive protein, erythrocyte sedimentation rate) may not be markedly elevated and are not specific.

Less often, infants can present with overt sepsis that involves bacteremia and focal limb abnormality that is not the most prominent symptom.

 Rarely, infection can result from penetrating trauma from instrumentation or procedures (eg, catheters, heel stick).

Plain radiography is important for evaluating for fracture, but destructive bony changes from infection will not be apparent until at least 10 days after the onset of symptoms. 

The sensitivity of magnetic resonance imaging (MRI) for detecting changes consistent with osteomyelitis approaches 100%.

Bone scans in neonates can be nondiagnostic. 

Ultrasonography of the knee in a preterm neonate may not reveal a significant effusion and is of little utility in the patient described in the vignette, in whom changes already are evident on MRI.

 Removal of the central venous catheter may be warranted if blood cultures reveal a pathogen but is unnecessary if they are negative.

---

Q 5:


During the 1-week health supervision visit, a mother who is exclusively breastfeeding asks about vitamin and iron supplementation for her healthy term infant. She explains that her previous child, who was born at 30 weeks’ gestation, was discharged with an oral iron supplement and vitamins.
Of the following, the MOST appropriate oral supplement to initiate for this infant at this visit is

A. calcium
B. folic acid
C. iron
D. vitamin D
E. vitamin K

Answer :

D

The most appropriate oral supplement to initiate at 1 week of age for an exclusively breastfeeding term infant is vitamin D.

In 2008, new guidelines from the American Academy of Pediatrics recommended that breastfed and partially breastfed infants be supplemented with 400 IU of vitamin D daily within days of birth.

Exclusive breastfeeding without adequate sun exposure or vitamin D supplementation is a risk factor for
vitamin D deficiency and rickets.

The term infant has adequate calcium stores, in contrast to the preterm infant, who is born
during the period when 80% of calcium, phosphorus, and magnesium are accrued. The term
infant also has adequate folate stores.

---------------------------------------------------
Q 6:

A 2-hour-old full-term newborn infant is noted by the nursing staff to be having episodes of cyanosis and apnea. Per nursery protocol they place an oxygen saturation monitor on him. When they attempted to feed him, his oxygen levels drop into the 60s. When he is stimulated and cries, his oxygen levels increase into the 90s. Which of the following is the most important next step to quickly establish the diagnosis?

a. Ventilation perfusion scan

b. Echocardiogram

c. Hemoglobin electrophoresis

d. Passage of catheter into nose

e. Bronchoscopic evaluation of palate and larynx

D

Choanal atresia

Most neonates are obligate nose breathers and cannot breathe adequately through their mouths. Infants with choanal atresia have increased breathing difficulty during feeding and sleeping and improved respirations when crying. 

A variety of temporizing measures to maintain an open airway have been used, including oropharyngeal airways, positioning, tongue fixation, and endotracheal intubation, but surgical correction with placement of nasal tubes is most effective. 

The diagnosis can be made by failure to pass a catheter through the nose to the pharynx or by checking for fog developing on a cold metal instrument placed under each nares



Q 7:

A 1-week-old term female infant suddenly develops melena. The mother is healthy, and the pregnancy was normal. Delivery was attended by her family at home, but it was uncomplicated. The infant is breastfeeding. Hemoglobin is 6.7 g/dL (67 g/L), white blood cell count is 13,000/cu mm (13 x 109/L), and platelets are 599 x 103/cu mm (599 x 109/L)Of the following, the MOST likely cause of the bleeding is:

A.         factor VIII deficiency hemophilia
B.         factor IX deficiency hemophilia
C.         necrotizing enterocolitis
D.         rectal fissure
E.         vitamin K deficiency

Answer :

E


Home birth is associated with many clinical problems, including vitamin K deficiency.  The vitamin often is not administered with home births.

            The pathophysiology responsible for hemorrhagic disease of the newborn is complex. Vitamin K is required to activate the procoagulant factors II, VII, IX, and X as well as proteins C and S, all of which are synthesized in the liver. 

Neonatal hepatic immaturity impairs the synthesis of these factors and limits the effectiveness of vitamin K. 

Inefficient transplacental transfer of vitamin K also may be a contributing factor. 

Delayed colonization of the gut by bacteria (which become an endogenous source of vitamin K) is another factor that occurs with delayed feeding, breastfeeding, vomiting, severe diarrhea, and the use of antibiotics (including those that are present in human milk). 

All of these factors contribute to vitamin K deficiency, low levels of vitamin K-dependent factors, and when severe enough, clinical hemorrhagic disease of the newborn.

            Classic vitamin K deficiency can present with melena, large cephalohematomas, intracranial hemorrhage, and bleeding from the umbilical stump, injection sites, and after circumcision.

 Bleeding occurs most commonly from the second to seventh days of life in healthy, breastfed, and often term infants who have not received prophylactic vitamin K. 

It occurs rarely in formula-fed infants because of the supplemental vitamin K in those products. 

            Laboratory evaluation :

In vitamin K deficiency, the prothrombin time (PT) and partial thromboplastin time (PTT) are more prolonged than usual for a neonate, the vitamin K-dependent factors (factors II, VII, IX, and X and proteins C and S) are decreased, and non-vitamin K-dependent factors (factors V, VIII, and fibrinogen) and platelet counts are normal. 

D Dx :


            Bleeding in the neonate has many other etiologies. 

If thrombocytopenia accompanies a prolonged PT and PTT, disseminated intravascular coagulation is likely. 

Factor VIII and IX deficiency hemophilia will cause prolongation of the PTT but not the PT.

Liver disease prolongs the PT and PTT and decreases vitamin K-dependent factors, but factor V and fibrinogen also are decreased. Hepatic function is abnormal in contrast to the normal-for-age function seen in vitamin K deficiency. 

Disorders such as necrotizing enterocolitis and rectal fissures can result in gastrointestinal bleeding in the absence of coagulopathy. However, rectal fissures do not cause melena, and necrotizing enterocolitis rarely occurs in healthy term infants.

            Prophylactic vitamin K is used widely to prevent hemorrhagic disease of the newborn. 

Treatment of clinical hemorrhagic disease of the newborn necessitates frequent doses of subcutaneous or intravenous vitamin K1; intramuscular administration should be avoided. Improvement will occur within 24 hours with vitamin K1 alone, but plasma should be used to treat infants who are experiencing serious bleeding.

-------------------------------------------

Q 8:


A newborn female has a cardiac murmur. Before the cardiologist arrives to evaluate her, she has a seizure. Results of laboratory testing include a serum calcium level of 5.0 mg/dL (1.25 mmol/L). Subsequently, echocardiography reveals an aortic arch anomaly
Of the following, the MOST appropriate test to obtain now is:

A.         brainstem auditory evoked responses
B.         electroencephalography
C.         fluorescent in situ hybridization analysis of chromosome 22
D.         peripheral blood chromosome analysis
E.         thyroid function testing


Answer :

C


The infant described in the vignette has a number of features of DiGeorge syndrome. DiGeorge syndrome results from abnormal cervical neural crest migration into the derivatives of the third and fourth pharyngeal arches and pouches during early embryogenesis. 

The pattern of malformations includes hypoplasia or aplasia of the thymus and parathyroid glands and structural abnormalities of the great vessels. The defects lead to the classic clinical manifestations of deficient cellular immunity due to T-cell dysfunction, causing increased susceptibility to infection; hypocalcemia due to absent parathyroid hormone, resulting in hypocalcemic seizures; and aortic arch abnormalities. Some affected infants also have facial dysmorphic features, which can include hypertelorism, short palpebral fissures, short philtrum, micrognathia, and ear abnormalities.

            Most patients who have DiGeorge syndrome are found to have partial monosomy for the proximal long arm of chromosome 22 due to microdeletion of 22q11.2. This microdeletion can be detected by fluorescent in situ hybridization (FISH) using a molecular probe specific for the region. 

-----------------------------------

Q 9:



A 2-day-old boy has biphasic stridor that worsens with agitation. He has intermittent desaturations with bradycardia and a weak cry. Blood pressure is 80/60 mm Hg, and pulse rate is 112 beats/min.

Of the following, the MOST likely etiology of this child's condition is:




A. congenital subglottic stenosis
B. cystic fibrosis
C. hypoplastic left heart
D. innominate artery compression
E. tracheoesophageal fistula

Answer :

A


Stridor is produced by rapid, turbulent flow of air through a narrow segment of the airway. Biphasic stridor suggests an anatomic location at the glottic or subglottic level. Inspiratory stridor typically is produced by an obstruction above the vocal cords; expiratory stridor is produced by an intrathoracic site of obstruction.

Cystic fibrosis often presents with meconium ileus at birth and the development of chronic cough, respiratory distress, and failure to thrive later in life. Stridor is uncommon. 

Patients who have hypoplastic left heart syndrome do not have obvious stridor; rather, they present with signs of cyanosis and hypoperfusion. Signs of congestive failure usually appear within the first few days or weeks of life. 

Tracheoesophageal fistula presents with excessive oral secretions, choking, coughing, and cyanosis when feeding is attempted. Tracheomalacia may cause expiratory stridor, but biphasic stridor is uncommon.

 Innominate artery compression, although usually mild and asymptomatic, may cause expiratory stridor, cough, and recurrent pneumonias. Respiratory distress is uncommon.

----------------------------------------------------

Q 10:


A newborn female has an open neural tube defect, low-set ears, ventricular septal defect, and rib and vertebral column malformations.
Of the following, the MOST likely maternal condition that was present during this pregnancy is:

A.         alcoholism
B.         diabetes mellitus
C.         hypothyroidism
D.         iodine deficiency
E.         syphilis

Answer :

B


Maternal diabetes mellitus can have profound effects on the development and health of the fetus. The severity of the maternal disease and the subsequent fetal effects can vary considerably. Because the maternal diabetic state can be present from the time of conception, early prenatal effects can result in malformations, growth deficiency, and stillbirth. 

There is a threefold increase in malformations among offspring of diabetic mothers; the incidence is correlated with the severity and level of control of the maternal illness. The most common defects involve the heart, central nervous system, kidneys, and skeleton, as described for the infant in the vignette. 

Of the cardiac defects, ventricular septal defect, transposition of the great vessels, and dextrocardia are most common. Central nervous system defects can range from anencephaly or holoprosencephaly  to spina bifida  and hydrocephalus. Malformations of the lower spine also occur and are termed the caudal regression syndrome. 

The spine may be segmented defectively or terminate in the sacral or lumbar region, resulting in abnormal neurologic function below the level of the defect. Rib defects also may be seen. Although many types of malformations can occur in infants of diabetic mothers, holoprosencephaly and the caudal regression syndrome are characteristic.

            Fetal alcohol syndrome is characterized by prenatal growth deficiency, microcephaly, and cardiac defects. Neural tube and vertebral column defects are not common features. 

Maternal hypothyroidism has little effect on the fetus, which produces its own thyroid hormone; women who have untreated hypothyroidism have been reported to give birth to normal offspring.

 Maternal iodine deficiency can cause fetal deficiency of the mineral, which results in goiter, signs of cretinism, retarded bone growth, constipation, umbilical hernia, and mottling in the newborn. Prompt treatment with iodine is necessary to prevent mental retardation.

 Maternal syphilis can affect the fetal skin, mucous membranes, liver, central nervous system, and bones. Cardiac anomalies and open neural tube defects are not common features.

------------------------------

Q 11:

Of the following, the MOST accurate statement about energy expenditure of a preterm infant is that:

A.  a thermoneutral environment is effective in minimizing energy expenditure
B.  diet-induced thermogenesis is higher with continuous than with intermittent feeding
C.  metabolic cost of growth is higher with deposition of fat than with synthesis of protein
D.  physical activity is the major component of total energy expenditure
E.  resting metabolic rate decreases with advancing postnatal age

ANSWER :

A

The preterm neonate’s energy expenditure can be minimized by keeping the infant in a thermoneutral environment. 

The thermoneutral environment is a range of ambient temperatures within which the metabolic rate of the infant is minimal and the infant can maintain a normal body temperature without any regulatory changes in metabolic heat production or evaporative heat loss. The thermoneutral range varies with gestational age. In an unclothed resting adult, the lower limit of the thermoneutral range is 78.8°F to 82.4°F (26°C to 28°C) in an environment of 50% relative humidity and still air. Under similar conditions, the lower limit of the thermoneutral range is 89.6°F (32°C) or higher in a naked term neonate and 95°F (35°C) or higher in a naked preterm neonate.

            Diet-induced thermogenesis, also known as specific dynamic action, thermic effect of food, or postprandial thermogenesis, is the increase in metabolic rate that follows food intake. It represents the energy consumption necessary for digestion, absorption, and assimilation of nutrients. The magnitude of increase in energy expenditure following the ingestion of nutrients is estimated to vary between 4% and 30% in both term and preterm neonates. Diet-induced thermogenesis is lower with continuous than with intermittent enteral feeding.

            Metabolic cost of growth represents the energy required for the formation of new tissue, and it varies with the composition of the synthesized tissue. The cost of depositing absorbed dietary fat into adipose tissue is much less than that of synthesizing new protein. The overall metabolic cost of growth in neonates is estimated at approximately 4.4 kcal/g of weight gain.

            Energy expenditure increases with physical activity, but because neonates sleep 80% to 90% of the time, physical activity is a small component of their energy expenditure compared with that of adults. It is estimated that physical activity contributes to only about 10% of the total energy expenditure in preterm neonates.

            Resting metabolic rate increases steadily from birth in both term and preterm neonates. The resting metabolic rate in term neonates is estimated at approximately 40 kcal/kg per day at 3 days of postnatal age, increasing to approximately 60 kcal/kg per day at 3 months of postnatal age. A similar but smaller increase in resting metabolic rate is observed in preterm neonates.

-----------------------------


Q 12 :



A pregnant woman is diagnosed as having active pulmonary tuberculosis at the time of delivery. She is placed on appropriate chemotherapy after delivering a healthy-appearing term infant.
Of the following, the MOST appropriate management of the infant includes separation from the mother:

A. for 1 month
B. until the infant begins isoniazid
C. until the infant receives bacillus Calmette-Guerin (BCG) vaccine
D. until the infant undergoes skin testing
E. until the mother is no longer contagious


Answer :

B



the maternal infection. Although protecting the infant from infection is of paramount importance, separation from the mother should be avoided when possible. Recommendations of the American Academy of Pediatrics’ Committee on Infectious Diseases are determined by the type of maternal infection and include:

      If the mother has a positive skin test, normal findings on chest radiography, and is asymptomatic, no separation is required. The newborn needs no special evaluation or therapy. Because a positive skin test result could be a marker of an unrecognized case of contagious tuberculosis within the household, other household members should have a skin tests and further evaluation.

         If the mother’s radiograph is abnormal, the mother and infant should be separated until the mother has been evaluated and, if tuberculosis is found, until the mother is receiving appropriate antituberculosis therapy. Other household members should have skin testing and further evaluation.

        If the mother’s chest radiograph is abnormal but not typical of tuberculosis and the history, physical examination findings, and sputum smear indicate no evidence of tuberculosis, the infant can be assumed to be at low risk for Mycobacterium tuberculosis infection and need not be separated from the mother. The mother and infant should receive follow-up care. Other household members should have skin testing and further evaluation.

            If the mother has clinical or radiographic evidence of possibly contagious tuberculosis, the case should be reported immediately to the local health department so that all household members can be investigated within several days. All contacts should have skin testing, a chest radiograph, and a physical examination. Women who have only pulmonary tuberculosis are not likely to infect the fetus, but they may infect their infant after delivery. Congenital tuberculosis is rare, but in utero infections can follow maternal M tuberculosis bacillemia. The infant should be evaluated for congenital tuberculosis and tested for human immunodeficiency virus infection. If a newborn is suspected of having congenital tuberculosis, a skin test, chest radiograph, lumbar puncture, and appropriate cultures should be obtained promptly. The skin test result usually is negative in newborns who have congenital or perinatally acquired infection. Hence, regardless of the skin test results, the infant should be treated promptly with isoniazid, rifampin, pyrazinamide, and streptomycin or kanamycin. The placenta should be examined histologically and cultured for M tuberculosis. The mother should be evaluated for the presence of pulmonary or extrapulmonary (including uterine) tuberculosis. If findings on the maternal physical examination or chest radiograph support the diagnosis of tuberculosis, the newborn should be treated with regimens recommended for tuberculous meningitis, excluding corticosteroids. If meningitis is confirmed, corticosteroids should be administered. Drug susceptibilities of the organism recovered from the mother, infant, or both should be determined. If the infant is receiving isoniazid, separation is not necessary. Other household members should have skin testing and further evaluation.

      If congenital tuberculosis is excluded, isoniazid is administered until the infant is 3 or 4 months of age, at which time the skin test should be repeated. If the skin test result is positive, the infant should be reassessed for tuberculosis. If disease is not present, isoniazid should be continued for at least 9 months. If the purified protein derivative test is negative and the mother and other household contacts who have tuberculosis have good adherence and response to treatment and are no longer contagious, isoniazid may be discontinued. The infant should be evaluated at monthly intervals during treatment.

        If the mother has disease due to multiple drug-resistant M tuberculosis or adheres poorly to treatment and directly observed therapy is not possible, the infant should be separated from the ill mother and bacillus Calmette-Guérin (BCG) immunization considered for the infant. Because the response to BCG in infants may be delayed and inadequate for prevention of tuberculosis, directly observed therapy for the mother and infant is preferred.

            M tuberculosis usually is spread via airborne transmission, with inhalation of droplet nuclei produced by an adult or adolescent who has contagious, cavitary, pulmonary tuberculosis. The duration of contagiousness of an adult receiving effective treatment depends on drug susceptibilities of the organism, the number of organisms in sputum, and the frequency of cough. Although contagiousness usually lasts only a few weeks after initiation of effective drug therapy, it may extend further, especially when the patient does not adhere to medical therapy or is infected with a resistant strain. If the sputum is negative for organisms on three smears and coughing has ceased, the person is considered noncontagious. Children younger than 12 years of age who have primary pulmonary tuberculosis usually are not contagious because their pulmonary lesions are small, cough is minimal or nonexistent, and there is little or no expulsion of bacilli.

-----------------------------------------------------------------------

Q 13 :



A 700 g infant presents with abdominal distension, excessive gastric residuals, and bloody stools. Physical examination reveals lethargy, poor perfusion, and recurrent apnea. Abdominal examination reveals tenderness, guarding, and erythema. You suspect necrotizing enterocolitis (NEC).
Of the following, the MOST accurate statement about NEC is that:

A.  age at onset is inversely related to gestational age at birth
B.  it is more common among critically ill than convalescing neonates
C.  pneumatosis intestinalis is the earliest radiographic sign
D.  strictures that occur as a late complication appear most frequently in the ileum
E.  the incidence is higher among Caucasian than African-American infants

Answer :

A



The age of onset of necrotizing enterocolitis (NEC) is inversely related to gestational age at birth. 

The earliest radiographic sign of NEC is generalized bowel distension. Other nonspecific findings on abdominal radiographs include bowel wall thickening and the presence of intraperitoneal fluid. Pneumatosis intestinalis  represents gas in the bowel wall and usually confirms the diagnosis of NEC.

 Pneumatosis intestinalis can extend into the portal venous circulation and be visible as linear branching lucencies overlying the liver. Portal venous gas usually is associated with severe disease.

            Strictures (Figure 20B) are the most common long-term gastrointestinal complication of NEC, occurring in 10% to 35% of survivors. 

-----



Q 14






An 800 g newborn whose estimated gestational age is 26 weeks is experiencing respiratory distress. Maternal history is significant for spontaneous preterm labor, rupture of membranes for fewer than 2 hours, and precipitous vaginal delivery. Chest radiography shows diffuse haziness with a reticulogranular pattern. You begin administration of surfactant by intratracheal instillation as well as mechanical ventilation.

Of the following, surfactant treatment is MOST likely to increase the incidence of:



A. bronchopulmonary dysplasia

B. intraventricular hemorrhage

C. pneumothorax

D. pulmonary hemorrhage

E. retinopathy of prematurity

Answer :

D

Pulmonary hemorrhage is a potential complication of surfactant treatment.


Both prophylactic and rescue administration of surfactant have been shown to decrease the incidence of pneumothorax and other pulmonary air leaks.

            The improvement in cardiopulmonary stability and oxygenation induced by surfactant therapy may protect preterm infants from nonpulmonary complications, including retinopathy of prematurity (ROP).

------------------------------

Q15 :



A newborn has hepatosplenomegaly, purpuric rash, jaundice, thrombocytopenia, and microcephaly. Computed tomography of the head demonstrates cerebral calcifications.
Of the following, the MOST appropriate diagnostic testing for this infant includes:

A.  maternal human immunodeficiency virus serology
B.  serologic testing of mother and infant for cytomegalovirus
C.  serologic testing of mother and infant for Toxoplasma
D.  VDRL on infant and maternal sera
E.  viral culture of swabs of infant’s throat and conjunctivae

Answer :

C



The congenital infections most likely to present with the constellation of findings described for the infant in the vignette include toxoplasmosis and cytomegalovirus (CMV) infection. Human immunodeficiency virus (HIV) and herpes simplex virus usually are acquired at the time of delivery, and the infant generally is asymptomatic at birth. Therefore, maternal HIV serology and viral culture of swabs from the infant’s throat and conjunctivae for HSV are unlikely to yield a diagnosis. Congenital syphilis also rarely is symptomatic at birth, although the most common symptoms include rash , snuffles, and bony changes.

            Diagnostic testing is the best means to distinguish CMV infection from toxoplasmosis because many of their clinical features overlap. Toxoplasmosis is more apt to present with chorioretinitis and scattered cerebral calcifications; CMV infection more frequently is associated with periventricular calcifications . CMV is diagnosed best by culture of the infant’s urine in the first 3 to 4 weeks of life. Serologic testing of maternal and infant sera is the best method for diagnosing congenital toxoplasmosis, but it is less useful in identifying CMV infection.


-----


Q16:



A newborn whose estimated gestational age is 34 weeks has had worsening respiratory distress since birth. Maternal history is significant for prolonged premature rupture of membranes, abdominal tenderness, foul-smelling amniotic fluid, and fever. Chest radiography reveals bilateral patchy infiltrates and fluid in the costophrenic angles. Blood samples are obtained for white blood cell count with differential and culture, and antibiotic treatment is started.

Of the following, the MOST appropriate initial combination of antibiotics is:



A.  ampicillin and gentamicin


B.  ceftazidime and tobramycin

C.  imipenem and cilastin

D.  trimethoprim-sulfamethoxazole

E.  vancomycin and amikacin

Answer :

A



The choice of antimicrobial agents for treatment of suspected or proven neonatal bacterial sepsis during the first days of life (early-onset sepsis) is based on the prevalent organisms responsible for the infection and the pattern of their antimicrobial susceptibility. The organisms most likely to be encountered in early-onset neonatal sepsis include group B streptococci, Escherichia coli, Listeria monocytogenes, Haemophilus influenzae, and enterococci. Ampicillin is effective against most gram-positive organisms and gentamicin against most gram-negative organisms associated with early-onset neonatal sepsis, making this combination one of the most commonly used for this indication.



-----------

Q 17 :



You are examining a newborn in the nursery and palpate a large mass in the abdomen.


Of the following, the MOST likely diagnosis is:





A.  autosomal dominant polycystic kidney disease


B.  horseshoe kidney


C.  multicystic kidney dysplasia

D.  renal vein thrombosis

E.  Wilms tumor

Answer

C



A palpable abdominal mass in a newborn constitutes a medical emergency. The most common cause of an abdominal mass in the neonatal period is hydronephrosis. One common cause of hydronephrosis is multicystic kidney dysplasia (MKD) .

 This congenital malformation is caused by obstruction to urine flow during in utero development, which results in abnormal parenchymal development. Renal ultrasonography reveals multiple cysts scattered throughout the renal parenchyma, with marked echogenicity of the parenchyma, indicating nonspecific renal dysplasia. The cysts are of varying size, often replacing normal renal tissue. Because the anomaly usually is unilateral, most children who have MKD have normal renal function. However, because at least 50% of patients have an abnormality of the contralateral kidney, voiding cystourethrography (VCUG) to evaluate for vesicoureteral reflux is essential. Other anomalies of the contralateral kidney include ureteropelvic junction obstruction (with hydronephrosis), duplicated ureters, renal dysplasia, and hydronephrosis. If MKD is bilateral, renal failure is assured.

Autosomal dominant polycystic kidney disease (ADPKD) is a very common cause of renal failure in adults. However, because it is a very slowly progressive disease, it rarely is seen in newborns. ADPKD typically presents with hematuria, urinary tract infection, and hypertension. Although horseshoe kidneys are infrequently observed in newborns, they may present with urinary tract infections, hematuria, or abdominal mass.

            Nephroblastoma is a general term used to describe a tumor of the kidney. The most common cause in early childhood is Wilms tumor, which presents as an abdominal or flank mass and may be heralded by hematuria and rarely, hypertension. It can be associated with other congenital anomalies, including genitourinary anomalies, hemihypertrophy, aniridia, gastrointestinal anomalies, polydactyly, and hydrocephalus. Although this is the most common solid tumor in childhood, it rarely presents during the newborn period.

            The typical presentation of renal vein thrombosis in a child is gross hematuria and an abdominal mass. Although rare, it often results in complete loss of function of the affected kidney.


-----------------------------

Q 18





A term newborn whose growth is appropriate for gestational age develops irritability, jitteriness, and tremulousness at 7 days of life. Physical examination reveals flushed cheeks, sweating, prominent eyes, and hepatosplenomegaly. Axillary temperature is 100.4°F (38°C), heart rate is 210 beats/min, respiratory rate is 48 breaths/ min, and blood pressure is 88/56 mm Hg. Muscle tone and deep tendon reflexes are normal.
Of the following, the MOST likely diagnosis is:

A. congenital heart disease
B. familial dysautonomia
C. intrauterine infection
D. narcotic withdrawal
E. neonatal thyrotoxicosis

Answer

E



Most cases of neonatal thyrotoxicosis  are caused by transplacental transfer of thyroid-stimulating hormone (TSH) receptor-stimulating antibodies from the mother. Maternal history often includes Graves disease, and maternal antibody titer may influence symptoms in the neonate. The symptoms and signs of neonatal thyrotoxicosis result from an increased metabolic rate, a generalized enlargement of the reticuloendothelial system, high-output cardiac failure, and exophthalmos of a variable degree. A goiter may be barely visible or large enough to cause tracheal compression. The diagnosis of neonatal thyrotoxicosis can be confirmed by measurements of serum free thyroxine and TSH receptor-stimulating antibody titer.

-----


Q  19



You are reviewing results of head ultrasonography performed on a 4-week-old extremely low-birthweight infant. The scan shows a large, encapsulated, fluid-filled cavity in the right cerebrum. The infant has required prolonged ventilator assistance and parenteral nutrition through a central venous catheter. She also has received broad-spectrum antibiotic therapy for multiple episodes of suspected sepsis.

Of the following, the MOST likely organism to cause this brain lesion is:



A.  Citrobacter diversus

B.  Clostridium perfringens

C.  Gardnerella vaginalis

D.  Leptospira canicola

E.   Yersinia enterocolitica

Answer

A



Citrobacter diversus causes sporadic and epidemic neonatal sepsis and meningitis. It is uniquely associated with brain abscesses, which usually are multiloculated and located in the cerebrum. The pathogenesis of brain abscess caused by C diversus involves cerebral vasculitis, with infarction and bacterial invasion of the necrotic tissue. Early manifestations of brain abscess include increased intracranial pressure, focal cerebral signs, and meningitis. The disease is associated with a high fatality rate, and mental retardation is common among survivors.

            Clostridium perfringens rarely is isolated in the neonate. Infection with this pathogen usually presents as omphalitis, localized cellulitis, necrotizing fasciitis, or generalized septicemia. Clostridial sepsis may include active hemolysis, hyperbilirubinemia, and hemoglobinuria.

            Gardnerella vaginalis is a gram-negative coccobacillus that is present in the genital tracts of up to one third of pregnant women. Infection in the neonate usually occurs in early postnatal life. Most infants are asymptomatic, but some may have signs and symptoms of congenital pneumonia.

            Leptospira canicola infection also is rare in the neonate. The organism usually is acquired by the transplacental route and largely affects the liver in the neonate.

            Yersinia enterocolitica is a rare pathogen in the neonate. Infection with this pathogen causes watery diarrhea, fecal blood, and other symptoms and signs of gastroenteritis. Rarely, autoimmune manifestations, such as arthritis and erythema nodosum, may occur.


--

Q 20



A newborn who weighs 4,700 g and whose estimated gestational age is 37 weeks has a blood glucose concentration of 18 mg/dL (1.00 mmol/L) at 30 minutes after birth. Maternal history is significant for type 1 diabetes mellitus. Blood count reveals polycythemia. Echocardiographic examination reveals septal hypertrophy of the heart.

Of the following, the MOST important cause of hypoglycemia in this infant is:



A. abnormal gluconeogenesis

B. abnormal glycogenolysis

C. depleted liver glycogen stores

D. excess catecholamine secretion

E. increased pancreatic insulin secretion

Answer

E

Increased pancreatic insulin secretion is the cause of hypoglycemia in an infant of a diabetic mother. In the absence of adequate glycemic control during pregnancy, diabetes causes maternal hyperglycemia, which is paralleled by fetal hyperglycemia. Persistent or recurrent fetal hyperglycemia stimulates the fetal pancreas and causes beta-cell hypertrophy and hyperplasia, with a resultant increase in insulin content and secretion. Upon separation of the fetus from the mother at birth, the transplacental transfer of glucose is interrupted. In the absence of an adequate exogenous intake of glucose, the hyperinsulinemic neonate becomes hypoglycemic. This hypothesis, proposed by Pedersen, is supported by the observation of high blood levels of insulin in the neonate. 

-------

Q 21



You are attending the birth of an infant whose mother smoked two packs of cigarettes per day during the pregnancy.
Of the following, the finding that would be MOST likely to be present in the newborn is:

A. growth restriction
B. hydronephrosis
C. microcephaly
D. respiratory distress syndrome
E. talipes equinovarus

Answer :

A


Tobacco smoking during pregnancy causes fetal hypoxia and morphologic changes in the placenta (eg, placenta previa, placental abruption) and premature rupture of the membranes. These adverse effects result in an increased risk for intrauterine growth restriction, preterm birth, and in some cases, late fetal demise. Maternal smoking also is associated with increased risks for postneonatal morbidity and mortality, including poor lung development, asthma, respiratory infections, and sudden infant death syndrome.


Q 22


A 3-week-old infant is brought to you for evaluation of poor feeding and lethargy. On physical examination, you note decreased movement of the right leg. Hip aspiration confirms the diagnosis of septic arthritis.

Of the following, the MOST likely causative organism in this patient is:



A.  Escherichia coli

B.  Group A Streptococcus

C.  Group B Streptococcus

D.  Haemophilus influenzae type B

E.   Listeria monocytogenes

The Answer

C

The most common organisms associated with neonatal septic arthritis are group B Streptococcus, Staphylococcus aureus, and coliform bacteria. Haemophilus influenzae type b (Hib) is much less prevalent now in the older child because of the use of the Hib vaccine. Group A Streptococcus, Escherichia coli, and Listeria monocytogenes are uncommon organisms causing septic arthritis in the neonate

-----------------

Q 23


A male infant is born at an estimated gestational age of 34 weeks. His body measurements are: weight, 1,200 g (<3rd percentile); crown-heel length, 41 cm (3rd percentile); and head circumference, 32 cm (50th percentile). Maternal history is significant for pregnancy-induced hypertension.
Of the following, the complication MOST likely to occur in this infant is:

A. anemia
B. hyperglycemia
C. hyperthermia
D. hypoxic-ischemic encephalopathy
E. respiratory distress syndrome

Answer

D


The failure of growth in the small-for-gestational age (SGA) infant described in the vignette can be attributed to chronic placental insufficiency from maternal hypertension. Uterine contractions can exacerbate the chronic hypoxia in the presence of a marginally functioning placenta. With repeated episodes of hypoxia, myocardial glycogen reserves are depleted, further limiting the cardiopulmonary adaptation to hypoxia in fetal life as well as at birth. If resuscitation is inadequate at birth, the combination of antepartum, intrapartum, and neonatal asphyxia places the infant at high risk for hypoxic-ischemic encephalopathy.

            The SGA infant is more likely to have polycythemia than anemia. Chronic fetal hypoxia from placental insufficiency induces erythropoietin synthesis, which increases red blood cell production in the fetus. Additionally, increased placental vascular resistance from maternal hypertension may promote a shift of placental blood to the fetus. Both of these factors place the SGA infant at high risk for polycythemia and associated hyperviscosity.

            The SGA infant is more likely to have hypoglycemia than hyperglycemia. The propensity for hypoglycemia may be attributed to depleted glycogen stores in the liver following chronic placental insufficiency and resultant disturbance in the transplacental transfer of nutrients. Additionally, the SGA infant is unable to stimulate gluconeogenesis in response to hypoglycemia. This limitation is believed to result not from a lack of nonglucose precursors, such as lactate, alanine, and glycerol, but from a lack of enzymes necessary for gluconeogenesis.

            The SGA infant may suffer hypothermia due to excessive heat loss rather than inadequate heat production. The excessive heat loss is related primarily to the deficient insulating layer of subcutaneous adipose tissue that results from chronic placental insufficiency and associated nutritional deprivation. A large surface area in relation to body weight, which is characteristic of the SGA infant, adds to the heat loss.

            Respiratory distress syndrome occurs less frequently and is less severe in the SGA infant than in the infant whose growth is appropriate for gestational age. Chronic fetal hypoxia in the SGA infant induces endogenous glucocorticosteroid secretion in response to stress that, in turn, accelerates fetal pulmonary maturation, including the machinery for surfactant synthesis and secretion.

-------------------------

Q 23


You are seeing a 2-week-old infant for the first time in your office. On physical examination, you note ptosis of the right upper eyelid. Findings on the remainder of the physical examination are normal.
Of the following, the MOST likely cause for the ptosis in this patient is:

A. botulism
B. brainstem glioma
C. Horner syndrome
D. malformed levator muscle
E. neonatal myasthenia gravis

Answer

D


Congenital ptosis is usually due to malformation of the levator muscle, which is the muscle that primarily elevates the eyelid. The levator muscle is innervated by the third cranial nerve. If the ptosis is severe, the infant’s vision will be greatly diminished. The infant often keeps the chin up in order to see. Absence of the faint lid crease will be present on the affected side. One or both eyebrows are often markedly elevated.
            The treatment for this condition is surgical correction. If untreated, amblyopia and loss of vision occur in many cases. Ophthamologic referral as soon as possible after birth is indicated.

            Myasthenia gravis is due to gradual destruction of the motor endplates at the neuromuscular junction. Circulating antibodies to the acetylcholine receptor bind to the receptor on the motor endplate, blocking its function. Ptosis is usually bilateral, and older patients also may complain of diplopia. Infants born to mothers who have myasthenia gravis may manifest neonatal myasthenia gravis, characterized by respiratory insufficiency, inability to suck or swallow, and generalized weakness and hypotonia. After the transplacentally acquired antibodies disappear, the infants have normal strength and are not at increased risk for myasthenia gravis. Congenital myasthenia gravis is a rare, often hereditary disorder that differs from transient neonatal myasthenia gravis. Congenital myasthenia gravis is not due to maternal antibodies and is almost always a permanent disorder without spontaneous remission.

            Botulism caused by preformed botulinum toxin is a type of food poisoning. It presents as a rapid onset of cranial nerve weakness; a descending paralysis of limb and respiratory muscles develops later. Botulism evolves rapidly over hours to days and has a progressive course. Infants who have botulism usually present with constipation, poor feeding, lethargy, and weak cry.

            Brainstem gliomas are uncommon in infants. They should be considered in any child who has cranial nerve abnormalities. Characteristic long tract findings include spasticity of limbs, exaggerated reflexes, positive Babinski sign, and ataxia.

            Mild ptosis with a lid crease, a small pupil (miosis), a difference in iris color (heterochromia) , and an inability to sweat (anhidrosis) on one side of the face are signs of Horner syndrome caused by sympathetic nerve interruption. In congenital cases, a history of brachial plexus injury resulting from a difficult delivery may help determine the etiology.


-----

Q 24



Ultrasonography of a 20-week fetus reveals urinary bladder distension and bilateral hydronephrosis. The volume of amniotic fluid is scant. The mother asks your advice regarding vesicoamniotic shunting as an intrauterine intervention.
Of the following, the MOST useful indicator of a favorable outcome following this procedure is:

A. amniotic fluid volume
B. bladder volume
C. female gender
D. fetal urine electrolyte levels
E.  renal pelvis diameter

Answer

A


Amniotic fluid volume is a good indicator of fetal renal function and of the potential success of vesicoamniotic shunting. Failure of urine to fill the amniotic space leads to progressive oligohydramnios, which results in poor pulmonary growth. The primary cause of death in prenatally diagnosed obstructive uropathy is pulmonary hypoplasia. The degree of renal dysplasia and pulmonary hypoplasia depends on the gestational age at onset and the duration of obstruction. Intrauterine relief of obstruction and restoration of amniotic fluid volume leads to normal lung growth and development, which is the basis for vesicoamniotic shunting as a means of preventing pulmonary hypoplasia.

-------------------------

Q 25


A newborn who weighs 1,800 g and whose estimated gestational age is 36 weeks has a central venous hematocrit of 75% (0.75). Maternal history is significant for smoking during pregnancy. The infant is lethargic, jittery, tremulous, and feeding poorly. Cardiopulmonary findings include tachypnea, tachycardia, and cyanosis. A partial exchange transfusion is ordered.

Of the following, the MOST appropriate diluent for partial exchange transfusion is:

A. albumin
B. fresh frozen plasma
C. glucose
D. normal saline
E. plasma substitute


Answer :


The infant described in the vignette has polycythemia-hyperviscosity syndrome. Polycythemia is defined as a central venous hematocrit in excess of 65% (0.65). Hyperviscosity of blood at this high hematocrit compromises microcirculation in various organs and makes the infant symptomatic. Hemodilution with a partial exchange transfusion is the treatment of choice. A randomized trial has shown that normal saline (crystalloid) is as effective as albumin (colloid) when used as replacement fluid in partial exchange transfusion for the treatment of polycythemia. Normal saline is easily available, relatively inexpensive, and free of infection hazard.

            Albumin (5%) also can be used as a diluent for partial exchange transfusion. It is believed to be retained in the intravascular space longer than a crystalloid solution because of its high oncotic pressure, thereby offering the theoretical advantage of a greater and more sustained hemodilution. However, this advantage is offset by the potential risk of protein leakage into the extravascular compartment, resulting in interstitial and pulmonary edema. 

            Fresh frozen plasma has a similar theoretical advantage to albumin with regard to efficient hemodilution, but it contains fibrinogen, which increases the viscosity of blood. Accordingly, fresh frozen plasma is relatively less effective in reducing high viscosity. Moreover, as a biologic product, it has the potential risk of infection.

            The use of glucose as a diluent for partial exchange transfusion is discouraged. The large bolus of glucose infusion that accompanies a partial exchange transfusion may cause hyperglycemia. The high osmolality (approximately 500 mOsm/L) of a 10% glucose solution also carries the risk of fluid shifts induced by a high osmotic load.

            Plasma substitute, which can be used as a diluent for partial exchange transfusion, has similar theoretical advantages and potential risks as albumin and fresh frozen plasma, but it offers no advantage over normal saline and is more expensive.


ليست هناك تعليقات:

إرسال تعليق