STI reviewer Flashcards
A 29-year-old G1P0 at 38 weeks gestation presents in active labor. Her GBS culture results are unknown, but her history includes a previous child with early-onset neonatal GBS sepsis.
What is the best course of action?
A) Await culture results before initiating treatment
B) No antibiotics needed if there are no signs of infection
C) Administer intrapartum IV Penicillin G immediately
D) Perform cesarean section to reduce GBS transmission
C) Administer intrapartum IV Penicillin G immediately
Rationale:
Why not A (Await culture results)?
→ If GBS status is unknown AND the patient has a history of a previous child with GBS sepsis, antibiotics must be given immediately.
Why not B (No antibiotics)?
→ This patient is at high risk for GBS transmission, so prophylaxis is necessary regardless of symptoms.
Why IV Penicillin G immediately (C)?
→ History of a prior GBS-infected infant is an automatic indication for intrapartum prophylaxis, even if culture status is unknown.
Why not D (Cesarean section)?
→ C-section does NOT prevent vertical transmission of GBS, so IV antibiotics remain the preferred method.
A 25-year-old pregnant woman at 22 weeks gestation presents for routine ultrasound. The scan reveals periventricular calcifications, microcephaly, and hepatosplenomegaly in the fetus. The mother reports a recent history of flu-like symptoms and works at a daycare center. Laboratory testing shows positive CMV IgM and low IgG avidity.
What is the most likely diagnosis?
A) Toxoplasmosis
B) Cytomegalovirus (CMV)
C) Rubella
D) Parvovirus B19
B) Cytomegalovirus (CMV)
Rationale:
Why CMV (B)?
→ Periventricular calcifications are pathognomonic for congenital CMV infection. Other key features include microcephaly, hepatosplenomegaly, and sensorineural hearing loss risk.
Why not A (Toxoplasmosis)?
→ Toxoplasmosis presents with diffuse intracranial calcifications, not periventricular calcifications.
Why not C (Rubella)?
→ Rubella presents with PDA, cataracts, and sensorineural deafness, not periventricular calcifications.
Why not D (Parvovirus B19)?
→ Parvovirus B19 is associated with hydrops fetalis, not periventricular calcifications.
A 19-year-old primigravida at 14 weeks gestation presents with a vesicular rash in different stages of healing on her face, trunk, and arms. She reports fever, malaise, and exposure to her 5-year-old nephew, who had “chickenpox” last week. Fetal ultrasound at 20 weeks shows limb hypoplasia and skin scarring.
Which infection is most likely responsible for the fetal abnormalities?
A) Parvovirus B19
B) Rubella
C) Cytomegalovirus
D) Varicella-Zoster Virus (VZV)
D) Varicella-Zoster Virus (VZV)
Rationale:
Why VZV (D)?
→ Classic congenital VZV findings include limb hypoplasia, skin scarring, and microcephaly.
Why not A (Parvovirus B19)?
→ Parvovirus causes hydrops fetalis and severe fetal anemia, not limb abnormalities.
Why not B (Rubella)?
→ Rubella causes congenital heart defects and sensorineural deafness, not vesicular rashes or limb defects.
Why not C (CMV)?
→ CMV leads to periventricular calcifications, not limb hypoplasia or skin scarring.
A 32-year-old woman at 28 weeks gestation presents with fever (39°C), myalgias, nonproductive cough, and dyspnea for three days. She is tachycardic and mildly hypoxic on room air. She has no history of influenza vaccination this season. Chest X-ray shows bilateral patchy infiltrates.
Which of the following is the most appropriate next step?
A) Supportive care and close monitoring
B) Oseltamivir antiviral therapy
C) Immediate delivery via C-section
D) Empiric IV antibiotics for pneumonia
B) Oseltamivir antiviral therapy
Rationale:
Why Oseltamivir (B)?
→ Pregnant women are at higher risk for severe influenza complications, and antiviral therapy reduces maternal morbidity.
Why not A (Supportive care)?
→ Influenza in pregnancy increases the risk of respiratory failure and preterm labor, requiring treatment.
Why not C (Immediate C-section)?
→ There is no indication for early delivery unless fetal distress occurs.
Why not D (Empiric antibiotics)?
→ Antibiotics are not first-line unless there is clear evidence of bacterial superinfection.
A 35-year-old pregnant woman at 30 weeks gestation presents with dyspnea, anosmia, fever, and persistent dry cough for 5 days. Oxygen saturation is 92% on room air. She reports household exposure to a co-worker who tested positive for COVID-19. A nasopharyngeal PCR test confirms SARS-CoV-2 infection.
Which of the following complications is most concerning in this patient?
A) Preterm labor
B) Congenital malformations
C) Limb hypoplasia
D) Severe fetal anemia
A) Preterm labor
Rationale:
Why Preterm labor (A)?
→ SARS-CoV-2 in pregnancy is associated with increased risk of preterm labor, thrombosis, and severe maternal morbidity.
Why not B (Congenital malformations)?
→ Unlike rubella, COVID-19 does not cause congenital defects.
Why not C (Limb hypoplasia)?
→ Limb hypoplasia is seen in congenital VZV infection, not COVID-19.
Why not D (Severe fetal anemia)?
→ Parvovirus B19, not COVID-19, is associated with fetal anemia.
A 27-year-old pregnant woman at 20 weeks gestation presents for routine ultrasound, which shows fetal hydrops (ascites, pleural effusion, skin edema), cardiomegaly, and polyhydramnios. She reports a recent exposure to a child with “slapped cheek” rash at her workplace.
What is the most likely cause of the fetal abnormalities?
A) Cytomegalovirus
B) Parvovirus B19
C) Toxoplasmosis
D) Rubella
B) Parvovirus B19
Rationale:
Why Parvovirus B19 (B)?
→ Parvovirus B19 infects fetal erythroid precursors, causing severe fetal anemia and hydrops fetalis.
Why not A (CMV)?
→ CMV does not typically cause hydrops fetalis but presents with periventricular calcifications.
Why not C (Toxoplasmosis)?
→ Toxoplasmosis causes diffuse intracranial calcifications but does not primarily lead to hydrops.
Why not D (Rubella)?
→ Rubella causes congenital heart defects and cataracts, not fetal hydrops.
A 26-year-old G1P0 woman at 35 weeks gestation presents with fever (38.5°C), tachycardia (maternal HR 110 bpm, fetal HR 175 bpm), uterine tenderness, and foul-smelling amniotic fluid. She denies any recent urinary tract infections. Speculum examination shows clear amniotic fluid pooling in the vagina.
What is the most likely diagnosis?
A) Group B Streptococcus (GBS) colonization
B) Pyelonephritis
C) Chorioamnionitis
D) Preterm labor without infection
C) Chorioamnionitis
Rationale:
Why Chorioamnionitis (C)?
→ Fever, maternal and fetal tachycardia, uterine tenderness, and foul-smelling amniotic fluid are classic signs of chorioamnionitis, an ascending infection from the vagina into the amniotic sac.
Why not A (GBS colonization)?
→ GBS colonization alone does not cause infection unless it progresses to chorioamnionitis, neonatal sepsis, or pneumonia.
Why not B (Pyelonephritis)?
→ Pyelonephritis presents with fever and flank pain but lacks uterine tenderness and foul-smelling amniotic fluid.
Why not D (Preterm labor without infection)?
→ Preterm labor does not cause fever, foul-smelling amniotic fluid, or maternal tachycardia.
A 28-year-old G2P1 at 38 weeks gestation presents in active labor with fever (39°C), uterine tenderness, and fetal tachycardia. Rupture of membranes occurred 18 hours ago. She has no known drug allergies.
What is the best next step in management?
A) Continue labor with expectant management
B) Administer IV antibiotics and expedite delivery
C) Start steroids for fetal lung maturity
D) Delay delivery until maternal fever resolves
B) Administer IV antibiotics and expedite delivery
Rationale:
Why IV antibiotics and delivery (B)?
→ Chorioamnionitis is an obstetric emergency requiring broad-spectrum IV antibiotics (Ampicillin + Gentamicin) and immediate delivery to prevent neonatal sepsis.
Why not A (Expectant management)?
→ Waiting increases the risk of maternal and neonatal complications such as sepsis and preterm birth.
Why not C (Steroids)?
→ Steroids are only given for preterm labor <34 weeks to aid fetal lung development. At 38 weeks, they are unnecessary.
Why not D (Delay delivery)?
→ Chorioamnionitis requires immediate delivery, as infection worsens with time.
A 32-year-old woman at 37 weeks gestation undergoes routine prenatal screening. A vaginal-rectal swab culture is positive for Group B Streptococcus (GBS). She has no known allergies.
What is the most appropriate next step in management?
A) Oral amoxicillin now and repeat culture at 39 weeks
B) IV Penicillin G during labor
C) IV Vancomycin now and repeat culture in one week
D) No treatment unless the baby shows signs of infection after delivery
B) IV Penicillin G during labor
Rationale:
Why IV Penicillin G during labor (B)?
→ GBS is not treated before labor because recolonization can occur. IV antibiotics are only given during labor to prevent neonatal GBS infection.
Why not A (Oral amoxicillin now)?
→ Oral antibiotics do not eliminate GBS colonization long-term, and re-testing at 39 weeks is not recommended.
Why not C (Vancomycin)?
→ Vancomycin is only used if the patient has a severe penicillin allergy.
Why not D (No treatment)?
→ GBS colonization increases the risk of neonatal sepsis, pneumonia, and meningitis, making intrapartum prophylaxis essential.
A 29-year-old G1P0 at 38 weeks gestation presents in active labor. Her GBS culture results are unknown, but her history includes a previous child with early-onset neonatal GBS sepsis.
What is the best course of action?
A) Await culture results before initiating treatment
B) No antibiotics needed if there are no signs of infection
C) Administer intrapartum IV Penicillin G immediately
D) Perform cesarean section to reduce GBS transmission
C) Administer intrapartum IV Penicillin G immediately
Rationale:
Why IV Penicillin G immediately (C)?
→ A history of a prior GBS-infected infant is an automatic indication for intrapartum prophylaxis, even if the current culture status is unknown.
Why not A (Await culture results)?
→ Waiting for results would delay treatment and increase the risk of neonatal GBS infection.
Why not B (No antibiotics)?
→ GBS colonization can be asymptomatic but still lead to neonatal sepsis.
Why not D (Cesarean section)?
→ C-section does NOT prevent vertical transmission of GBS, so IV antibiotics remain the standard of care.
A 25-year-old pregnant woman at 16 weeks gestation has no symptoms but is found to have >100,000 CFU/mL of E. coli in her urine culture.
What is the most appropriate management?
A) No treatment needed
B) Nitrofurantoin or cephalexin
C) IV ceftriaxone
D) Delay treatment until symptoms develop
B) Nitrofurantoin or cephalexin
Rationale:
Why Nitrofurantoin or cephalexin (B)?
→ Asymptomatic bacteriuria must always be treated in pregnancy to prevent progression to pyelonephritis and preterm labor.
Why not A (No treatment)?
→ Untreated bacteriuria increases the risk of kidney infection, preterm labor, and low birth weight.
Why not C (IV ceftriaxone)?
→ IV antibiotics are reserved for pyelonephritis, not asymptomatic bacteriuria.
Why not D (Delay treatment)?
→ Early treatment prevents complications; waiting increases maternal and fetal risks.
A 28-year-old woman at 24 weeks gestation presents with fever (39°C), flank pain, nausea, vomiting, and costovertebral angle tenderness. Urinalysis shows WBC casts and pyuria.
What is the most appropriate treatment?
A) Oral nitrofurantoin
B) IV ceftriaxone
C) No antibiotics unless symptoms worsen
D) Trimethoprim-sulfamethoxazole
B) IV ceftriaxone
Rationale:
Why IV ceftriaxone (B)?
→ Pyelonephritis in pregnancy is an emergency requiring hospitalization and IV antibiotics to prevent sepsis.
Why not A (Oral nitrofurantoin)?
→ Oral antibiotics are insufficient for severe infections like pyelonephritis.
Why not C (No antibiotics)?
→ Untreated pyelonephritis increases the risk of preterm labor, sepsis, and maternal mortality.
Why not D (TMP-SMX)?
→ Trimethoprim-sulfamethoxazole is contraindicated in pregnancy due to folate inhibition.
A 28-year-old pregnant teacher at 10 weeks gestation presents with bilateral painful swelling of the parotid glands, fever, and malaise. She denies recent vaccinations. Examination reveals tender, swollen cheeks and mild orchitis in her partner.
Which of the following is the most likely complication in her pregnancy?
A) Congenital deafness
B) Spontaneous abortion
C) Microcephaly
D) PDA and cataracts
B) Spontaneous abortion
Rationale:
Why Spontaneous Abortion (B)?
→ Mumps infection during the first trimester increases the risk of miscarriage but does not cause congenital anomalies.
Why not A (Congenital deafness)?
→ Congenital deafness is a classic finding in Rubella, not Mumps.
Why not C (Microcephaly)?
→ Microcephaly is commonly associated with Cytomegalovirus (CMV) and Zika virus, not Mumps.
Why not D (PDA and cataracts)?
→ PDA and cataracts are features of congenital Rubella syndrome, not Mumps.
A 26-year-old pregnant woman at 18 weeks gestation presents with high fever, cough, coryza, conjunctivitis, and a maculopapular rash that started on her face and spread downward. On oral examination, you note white spots on an erythematous base inside her cheeks.
What is the most likely diagnosis?
A) Rubella
B) Measles (Rubeola)
C) Varicella
D) Parvovirus B19
B) Measles (Rubeola)
Rationale:
Why Measles (B)?
→ The presence of the classic “3 Cs” (Cough, Coryza, Conjunctivitis) along with a maculopapular rash and Koplik spots is diagnostic for Measles.
Why not A (Rubella)?
→ Rubella presents with postauricular lymphadenopathy and does not have the “3 Cs” or Koplik spots.
Why not C (Varicella)?
→ Varicella presents with a vesicular rash at different stages of healing, not a descending maculopapular rash.
Why not D (Parvovirus B19)?
→ Parvovirus B19 causes hydrops fetalis and “slapped cheek” rash in children, not Measles.
A 23-year-old unvaccinated woman at 12 weeks gestation presents with low-grade fever, lymphadenopathy (postauricular and occipital), and a pink maculopapular rash that spreads from the face downward. Fetal ultrasound at 22 weeks reveals congenital heart defects and cataracts.
Which of the following is the most likely diagnosis?
A) Measles
B) Rubella
C) Parvovirus B19
D) Cytomegalovirus
B) Rubella
Rationale:
Why Rubella (B)?
→ Rubella is characterized by postauricular and occipital lymphadenopathy, a descending rash, and congenital anomalies including PDA, cataracts, and congenital deafness.
Why not A (Measles)?
→ Measles presents with Koplik spots and does not cause congenital heart defects or cataracts.
Why not C (Parvovirus B19)?
→ Parvovirus B19 is associated with fetal hydrops and severe anemia, not congenital cataracts or heart defects.
Why not D (Cytomegalovirus)?
→ CMV causes periventricular calcifications and sensorineural hearing loss but not cardiac defects or cataracts.
A 35-year-old G2P1 woman at 37 weeks gestation presents for routine prenatal screening. Her vaginal-rectal culture tests positive for Group B Streptococcus (GBS). She has no known drug allergies.
What is the most appropriate management at the time of labor?
A) No treatment is needed
B) Intravenous penicillin G during labor
C) Oral amoxicillin now and repeat culture at 39 weeks
D) Elective cesarean section
B) Intravenous penicillin G during labor
Rationale:
Why IV Penicillin G during labor (B)?
→ GBS colonization is treated during labor, NOT before, because recolonization can occur. Intrapartum prophylaxis reduces the risk of neonatal sepsis, pneumonia, and meningitis.
Why not A (No treatment needed)?
→ Untreated maternal GBS colonization increases the risk of neonatal infection, requiring prophylaxis during labor.
Why not C (Oral amoxicillin now and repeat culture)?
→ Oral antibiotics before labor do not reliably eliminate GBS and are not the recommended approach.
Why not D (Elective cesarean section)?
→ C-section does NOT reduce the risk of GBS transmission; antibiotics are still required if labor begins before delivery.
A 22-year-old pregnant woman at 16 weeks gestation presents with a painless genital ulcer that healed spontaneously. She was lost to follow-up and now returns at 28 weeks with a maculopapular rash involving the palms and soles and generalized lymphadenopathy. VDRL and FTA-ABS tests are positive.
What is the most appropriate treatment?
A) Ceftriaxone
B) Doxycycline
C) Acyclovir
D) Penicillin G
D) Penicillin G
Rationale:
Why Penicillin G (D)?
→ Penicillin G is the ONLY recommended treatment for syphilis in pregnancy, as it crosses the placenta and prevents congenital syphilis.
Why not A (Ceftriaxone)?
→ Ceftriaxone is used for gonorrhea, not syphilis.
Why not B (Doxycycline)?
→ Doxycycline is contraindicated in pregnancy due to risks of fetal bone and teeth discoloration.
Why not C (Acyclovir)?
→ Acyclovir is used for herpes simplex virus, not syphilis.
A 27-year-old woman at 38 weeks gestation presents with multiple painful vesicular lesions on an erythematous base in her genital area. She has a history of recurrent HSV infections and did not take prophylactic antivirals during pregnancy.
What is the best next step in management?
A) Vaginal delivery with intrapartum IV acyclovir
B) Cesarean section
C) Observation and allow for spontaneous delivery
D) Empiric IV antibiotics
B) Cesarean section
Rationale:
Why Cesarean section (B)?
→ Active genital HSV lesions at delivery are an indication for cesarean section to prevent neonatal herpes, which can cause encephalitis and sepsis.
Why not A (Vaginal delivery with IV acyclovir)?
→ Acyclovir is used as prophylaxis starting at 36 weeks, but active lesions at delivery still require C-section.
Why not C (Observation and spontaneous delivery)?
→ Vaginal delivery in the presence of active lesions risks neonatal HSV transmission.
Why not D (Empiric IV antibiotics)?
→ HSV is a viral infection, so antibiotics are ineffective.
A 29-year-old woman at 34 weeks gestation is diagnosed with HIV during prenatal screening. Her viral load is 5,000 copies/mL. She has been compliant with antiretroviral therapy (ART), and her CD4 count is within normal limits.
What is the recommended mode of delivery?
A) Vaginal delivery
B) Cesarean section at 39 weeks
C) Induction of labor at 37 weeks
D) Cesarean section at 38 weeks if viral load > 1,000 copies/mL
D) Cesarean section at 38 weeks if viral load > 1,000 copies/mL
Rationale:
Why Cesarean at 38 weeks if viral load >1,000 copies/mL (D)?
→ HIV-positive mothers with a high viral load (>1,000 copies/mL) require a scheduled C-section at 38 weeks to reduce vertical transmission risk.
Why not A (Vaginal delivery)?
→ Vaginal delivery is only recommended if viral load is <1,000 copies/mL at 36 weeks.
Why not B (C-section at 39 weeks)?
→ Elective C-section is done at 38 weeks to minimize the risk of labor onset and rupture of membranes, which increases vertical transmission.
Why not C (Induction at 37 weeks)?
→ Induction at 37 weeks is not necessary unless there are obstetric indications.