Questions, Board Review

Board Review Questions: October 2022

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1. A newborn baby is presented for evaluation of yellow skin. The baby was born at home 17 hours ago by spontaneous vaginal delivery at 37 weeks' gestation; the mother received no prenatal care. The baby’s vital signs include P 178, R 66, and T 37°C (98.6°F); SpO2 is 97% on room air. What is the most concerning potential cause of this patient's symptoms?

A. ABO incompatibility
B. Breast milk jaundice
C. Familial nonhemolytic jaundice
D. Physiologic jaundice

The correct answer is A, ABO incompatibility.

Why is this the correct answer?
When considering the possible causes of jaundice, time of onset is a crucial branch point that provides clues to the underlying cause and its severity. Jaundice in the first 24 hours of life is an ominous finding because these patients are more likely to develop severe jaundice that could progress to kernicterus (hyperbilirubinemia-induced encephalitis). The factors that place a patient at high risk include a total bilirubin at discharge in a high-risk zone, gestational age of 35 to 36 weeks, jaundice in the first 24 hours, a sibling who required phototherapy, ABO incompatibility or hemolytic disease, breastfeeding but poor growth or feeding, and East Asian or Mediterranean ancestry. Hemolytic disease can lead to not only jaundice but also anemia, which can affect the patient's hemodynamic stability. A Coombs test can detect maternal IgG antibodies on the baby's RBCs; it should be included in the evaluation of this patient, as should testing for Hgb, liver function, total and fractionated bilirubin, and, possibly, blood typing for the neonate and birthing parent if this information is unknown.

Why are the other choices wrong?
• Jaundice develops in 30% of healthy breastfed infants and is 3 to 6 times more likely in a breastfed child than in one who is bottle Breast milk jaundice has two stages: early (starting within the first week of life) and late (starting in the first week, peaking by 2 weeks, and then resolving by 3 months). Early breast milk jaundice is likely related to the decreased volume or frequency of feeds. This can lead to dehydration and delayed meconium passage. Early breast milk jaundice may also be related to the decreased enterohepatic recirculation and immaturity of the liver in these children. Treatment for early breast milk jaundice is geared toward improving hydration (eg, increase to more than 10 feeds per day and possibly supplement with formula [not water or dextrose/H2O]) while continuing to breastfeed. Late breast milk jaundice is believed to be caused by properties of the breast milk (eg, beta-glucuronidase and nonesterified fatty acids), which seem to decrease bilirubin metabolism. Treatment for late breast milk jaundice is to temporarily withhold breastfeeding, although the birthing parent is advised to continue to pump. The bilirubin level should decline rapidly in 48 hours with this approach. Bilirubin levels generally peak on days 6 to 14. Phototherapy is used to decrease the rise of total bilirubin in any neonate of any gestational age. Phototherapy should be used when the rate of rise is greater than 5 mg/dL per 24-hour period or when advised to do so using either the bilirubin nomogram or bilirubin calculator.
• Familial nonhemolytic jaundice, also known as Gilbert disease, is a hereditary disorder that leads to decreased bilirubin metabolism. It is uncommon in neonates but is often found in older children and adults.
• Physiologic jaundice is related to polycythemia of newborns as well as the immaturity of the liver, which leads to an elevated unconjugated bilirubinemia. This peaks between days 3 and 5 and resolves spontaneously by 14 days of life.

REFERENCES

Schinasi DA. Jaundice: unconjugated hyperbilirubinemia. In: Shaw KN, Bachur EG, Chamberlain J, Lavelle J, Nagler J, Shook JE, eds. Fleisher & Ludwig's Textbook of Pediatric Emergency Medicine. 8th ed. Wolters Kluwer; 2021:294-300.

Mitra A, Wolff MS. Neonatal jaundice. In: Wolfson AB, Cloutier RL, Hendey GW, Ling LJ, Rosen CL, Schaider JJ, eds. Harwood-Nuss’ Clinical Practice of Emergency Medicine. 7th ed. Wolters Kluwer; 2021:1141-1145.


2. A 22-year-old woman presents after drinking a bottle of toilet bowl cleaner. She complains of nausea with one episode of nonbloody vomiting and epigastric abdominal pain. Her vital signs are BP 125/85, P 99, R 23, and T 37.3°C (99.1°F); SpO2 is 98% on room air. Assessment of her oropharynx is unremarkable, and her voice is normal. Abdominal examination reveals tenderness to palpation of the epigastrium without rebound or guarding. She says she wishes "it would just end." She has no history of suicide attempts. What is the most appropriate next step?

A. Admission for endoscopy and close monitoring
B. Emergent intubation
C. Gastric decontamination with activated charcoal
D. Gastric lavage with placement of an Ewald tube

The correct answer is A, Admission for endoscopy and close monitoring.

Why is this the correct answer?
In the setting of intentional overdose of a large amount of a strongly caustic agent, the appropriate recommendation is admission for close monitoring and serial examinations; endoscopy can be performed to grade the extent of the injury. Serious caustic acid injuries cause coagulation necrosis, a process in which hydrogen ions infiltrate tissues, which leads to killing of cells and formation of an eschar. This eschar protects against deeper injury, so caustic acids typically cause less damage than caustic alkalis. Despite this, ingestion of strong acids is associated with a higher mortality rate compared to alkali ingestions because of severe gastric damage. An anion gap acidosis (lactic) may result from tissue injury or impending shock. Notably, some acidic agents (eg, hydrochloric acid) may produce a non–anion gap acidosis, and the acid may be absorbed systemically. Household cleaning agents such as toilet bowl cleaners contain hydrochloric acid. This patient may have some degree of acidosis as indicated by her tachypnea. Psychiatric services are needed, but because she has symptoms of potential gastric injury, she should first be admitted to a medical service for serial abdominal examinations and monitoring for GI bleeding or perforation. Intentional ingestions are associated with higher grades of GI injury than accidental ingestions.

Why are the other choices wrong?
• This patient does not show evidence of chemical burn to the oropharynx or swelling of the upper airway, which would necessitate airway protection with emergent intubation. However, she does need endoscopy, which should be obtained in a controlled setting. Endoscopy should be performed within 12 hours of ingestion and not more than 24 hours afterward to avoid GI perforation during the procedure.
• Gastric decontamination with activated charcoal is contraindicated in caustic ingestions. Charcoal impairs visualization for endoscopy and does not bind well to most caustic agents.
• Gastric lavage is not indicated for caustic ingestions. For concern of coingestants, placement of a nasogastric or larger orogastric tube (eg, the Ewald) is contraindicated until an endoscopy has shown that gastric hemorrhage or perforation is not a risk.

REFERENCES

Hoyte C. Caustics. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen’s Emergency Medicine: Concepts and Clinical Practice. Vol 2. 9th ed. Elsevier; 2018:1890-1894.

Connors NJ, Carter WA. Caustic ingestions. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill Education; 2020:1296-1300.

UpToDate article on caustic esophageal injury in adults, available in full with a subscription

https://www.uptodate.com/contents/caustic-esophageal-injury-in-adults


3. Which characteristic do both staphylococcal and streptococcal toxic shock syndromes have?

A. Blood culture likely to be positive
B. High mortality rate
C. Infection associated with a retained foreign body
D. Toxin-producing gram-positive causative organism

The correct answer is D, Toxin-producing gram-positive causative organism.

Why is this the correct answer?
There are two classically described versions of toxic shock syndrome (TSS) — one caused by Staphylococcus aureus (staph TSS) and one by Streptococcus pyogenes (strep TSS). Both causative organisms are gram-positive bacteria that produce toxins that mediate their respective life-threatening syndromes. S. aureus(including MRSA) produces toxic shock syndrome toxin-1 (TSST-1) and enterotoxin type B, while S. pyogenesproduces streptococcal pyrogenic exotoxins. These toxins ("superantigens") cause fever, massive systemic inflammatory states, increased vascular permeability, hemodynamic instability, coagulopathy, and multiorgan failure. The hallmark of treatment is supportive care with aggressive antibiotic therapy for gram-positive organisms.

Why are the other choices wrong?
• Blood cultures are positive in fewer than 5% of staph TSS cases. However, cultures from retained foreign bodies, mucosal sites, and wounds are often positive and should be collected when possible. In contrast, blood cultures are positive in more than 60% of strep TSS cases.
• Strep TSS is associated with a high mortality rate, with a case fatality rate of 30% to 70%. The mortality rate for staph TSS is likely to be less than 3%.
• Although staph TSS is associated with retained foreign bodies (classically tampons), strep TSS is unrelated to this etiology. The incidence of staph TSS has decreased since the 1980s when highly absorbent tampons were removed from the market. However, tampon use remains a significant risk factor and is responsible for more than 50% of current staph TSS cases. Recognition and removal of foreign body nidus is critical to eliminate ongoing toxin production. Risk factors for strep TSS include skin and soft tissue infections, trauma, surgery, childbirth, and viral illnesses. These conditions are also risk factors for non–tampon-mediated staph TSS.

REFERENCES

Frackelton-Fernandez M. Bacteria. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 2. 9th ed. Elsevier; 2018:1573-1597.

Serrano KD. Sexually transmitted infections. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli's Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill Education; 2020:1013-1024.


4. A 31-year-old woman presents with seizures. She is 3 weeks postpartum. Her vital signs include BP 160/110, P 95, and T 37.1°C (98.8°F); SpO2 is 94% on room air. What medication should be given first?

A. Hydralazine
B. Lorazepam
C. Magnesium sulfate
D. Phenytoin

The correct answer is C, Magnesium sulfate.

Why is this the correct answer?
This patient's presentation is suggestive of eclampsia, which can occur in the third trimester of pregnancy or up to 4 weeks postpartum. The initial treatment of eclampsia is magnesium sulfate 4 to 6 g IV, followed by infusion at 1 to 2 g/hr. If the patient has signs of renal insufficiency, the dose should be decreased. Signs of magnesium toxicity include delayed reflexes, flaccid paralysis, hypotension, and respiratory compromise. If the patient continues to have hypertension after magnesium sulfate administration, consider a secondary antihypertensive medication such as hydralazine, labetalol, nifedipine, or sodium nitroprusside. Given the risk for ongoing seizures and complications from magnesium sulfate administration, all eclampsia patients require admission to an obstetric care setting with critical care capabilities.

Why are the other choices wrong?
• Hydralazine may be given to control blood pressure in a patient who develops eclampsia with hypertension. However, it is considered a secondary agent because magnesium sulfate can treat elevated blood pressure when given as the initial therapy for seizure activity.
• Although benzodiazepines such as lorazepam are an initial first-line agent for seizures, they are not indicated in the treatment of eclampsia. Benzodiazepines may be considered if magnesium toxicity is a concern and the patient continues to have seizures.
• Phenytoin is also an appropriate antiepileptic agent for typical patients with seizures, but it is not the first-line agent in eclampsia. Instead, eclampsia patients should receive magnesium sulfate and be admitted into an obstetric care setting with critical care capabilities.

REFERENCES

Cunningham FG, Leveno KJ, Bloom SL, et al. Hypertensive disorders. In: Patel S, Roberts S, Rogers V, Zink A, Duryea E, Morgan J, eds. Williams Obstetrics Study Guide. 25th ed. McGraw-Hill Education; 2018:710-755.

Young JS. Maternal emergencies after 20 weeks of pregnancy and in the peripartum period. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill Education; 2020:631-637.

Frontera JA, Ahmed W. Neurocritical care complications of pregnancy and puerperium. J Crit Care. 2014 Dec;29:1069-1081.


5. A 35-year-old man presents via ambulance with hypotension and tachycardia after a motor vehicle crash. He does not know his blood type. Which blood type is the best choice for transfusion in this scenario?

A. AB–
B. AB+
C. O–
D. O+

The correct answer is D, O+.

Why is this the correct answer?
Whenever possible, patients should receive typed and crossmatched blood for transfusion. However, blood typing and crossmatching can take time, and some patients require immediate transfusion of uncrossmatched blood. When giving uncrossmatched blood, it is important to use type O blood because no A or B antigens are present on the RBCs. Men may receive either O– (Rhesus antigen negative) or O+ (Rhesus antigen negative) blood, but most experts recommend transfusing O+ blood in order to save the limited supply of O– blood for female transfusion patients. Women should receive O– blood to avoid Rh sensitivity, which can result in future childbearing complications. Transfusing incorrect or non–type O blood to a patient can result in an acute hemolytic reaction, which can be fatal. Rhesus antigen does not significantly increase the risk of acute hemolytic reaction in transfusion patients.

Why are the other choices wrong?
• AB– blood has both A and B antigens on the RBCs. It carries the highest risk of causing an acute hemolytic reaction in an uncrossmatched blood transfusion.
• Similar to AB– blood, AB+ blood has both A and B antigens on the RBCs. Thus, AB+ blood also carries a high risk of causing an acute hemolytic reaction in an uncrossmatched blood transfusion.
• O– blood is the least reactive blood type and is recommended for empiric transfusion of all patients who can bear children. Due to the limited quantity of O– blood, other patients (including men and postmenopausal women) should receive O+ blood in an emergent situation when feasible.

REFERENCES

Emery M. Blood and blood components. In: Walls RM, Hockberger RS, Gausche-Hill M, et al, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. Vol 2. 9th ed. Elsevier; 2018:1455-1462.

Coli CJ, Santen SA. Transfusion therapy. In: Tintinalli JE, Ma OJ, Yealy DM, et al, eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide. 9th ed. McGraw-Hill Education; 2020:1494-1500.

American Red Cross information about blood types
https://www.redcrossblood.org/donate-blood/blood-types.html

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