Obstetrics and Gynecology
High Yield USMLE Step 2 CK Notes
Welcome to the Obstetrics and Gynecology High-Yield Notes for Step 2 CK.
These are the most commonly tested topics on the exam—ideal for quick review in your last
2 weeks before the exam, when you're short on time, or when you're just starting out and
want to focus on what is high yield. Created and peer-reviewed by physicians who scored
260+ on Step 2 CK in a Q&A style to reinforce active learning.
How to use this file
y
Read the question ➔ cover the answer ➔ self-quiz before revealing.
u
Review the NOTES ➔ they include high-yield details you don't want to
miss.
h G Need tutoring? Scan the QR code or visit The Match Guy Tutoring.
c
Don’t forget to watch the video lessons that go with this file. Learn
t
more here.
Ma
Prenatal Testing & Supplementation
The 1. A 35F 10 weeks gestation presents to you in her first trimester with elevated beta HCG,
decreased PAPP-A, and increased nuchal translucency. What's the diagnosis?
➔ Down syndrome (1st trimester infant + Elevated beta HCG + low PAPPA ➞ think Down
Syndrome)
Note: a) Other markers for Down syndrome (trisomy 21) include increased inhibin
levels, decreased estriol, and decreased AFP levels.
Trisomy B-HCG PAPPA AFP Inhibin Estriol
21 ⇑ ⇓ ⇓ ⇑ ⇓
18 ⇓ ⇓ ⇓ ⇓ or - ⇓
13 - - - - -
b) First-trimester screen is often part of non-invasive prenatal testing (NIPT) for early
aneuploidy risk assessment. If positive, next step ➞ do diagnostic testing ➞ CVS at 10–
13 weeks or amniocentesis at ≥15 weeks.
© 2025 TheMatchGuy LLC. All rights reserved. Page 1
Version 1.0 August 2025. No part of this document may be reproduced or distributed without written permission. For personal study only. Medical information
herein is for educational purposes and does not constitute clinical advice. Always confirm with current guidelines and your institution’s policies.
, Advanced maternal age (≥35 years) increases the risk of chromosomal anomalies ➞
these screens are especially important
c) Cell-free fetal DNA ➞ A highly useful test that can be used to detect fetal abnormalities
in <10 weeks of gestation. It is a non-invasive test with a very high sensitivity to detect
chromosomal abnormalities.
d) Remember that high AFP is indicative of abdominal wall defects, multiple gestations,
incorrect dating, and neural tube defects
2. A 22F presents to your clinic in her first trimester to establish care. She has an incomplete
history of childhood vaccinations. Which vaccine-preventable illness does she need to get
tested for?
➔ Rubella (Part of the MMR vaccine ➞ Live attenuated ➞ Contraindicated in pregnancy (if
Rubella IgG is negative, wait and vaccinate postpartum before you discharge the patient)
uy
Note: a) If she gets infected ➞ It can lead to Congenital Rubella Syndrome ➞ Triad of
Sensorineural hearing loss, Congenital cataracts, and Patent Ductus Arteriosus)
G
b) Several tests are recommended on the first prenatal visit. Here is a table you would
want to remember.
h
atc RhD Antigen/Antibody
Urine Culture
M
Urine dipstick for protein
For infections, you can use
e
HIV the following mnemonic:
“Hi (HIV), We (Varicella),
h
Chlamydia
aRe (Rubella), Happy
Initial Prenatal Visit
T Syphilis (VDRL/RPR) Babies (Hep B), and we will
Happily See (Hep C), the
Hep B (HbsAg) rainbow Colored
(Chlamydia) Sky (Syphilis).”
Hep C (Anti-HCV ab)
Rubella
Varicella
Hemoglobin/Hematocrit
Antibody Screen (if RhD
24-28 weeks negative)
1-hour 50g Glucose
tolerance test
Group B Streptococcus
36-38 weeks
Rectovaginal Culture
© 2025 TheMatchGuy LLC. All rights reserved. Page 2
, c) Asymptomatic bacteruria on urine culture ➞ Needs to be treated with a first-generation
cephalosporin or nitrofurantoin.
3. A 33F woman comes to you with severe right adnexal pain. On ultrasound, you find
ectopic pregnancy. Should this patient receive RhoGAM?
➔ Yes (Rho(D) immune globulin is given to Rh-negative mothers to prevent
alloimmunization from exposure to Rh-positive fetal red blood cells.)
Ectopic pregnancy, like any pregnancy loss or complication with potential fetomaternal
hemorrhage, can lead to maternal sensitization ➞ Administer RhoGAM prophylactically.)
Note: a) When NOT to Give RhoGAM:
The patient is Rh-positive
Father is confirmed Rh-negative (no Rh+ fetus possible)
The mother is already sensitized (Rh antibody screen positive) ➞ RhoGAM is not
effective at that point.
y
b) When to give RhoGAM:
u
If the mother is RhD-negative and has no RhD antibodies (i.e., antibody screen
negative).
h G
Indications for RhoGAM
tc
28-32 weeks of gestation
a
<72 hours after delivery
M
Ectopic pregnancy
e
Threatened Abortion
h
Hydatidiform mole
TAmniocentesis
Chorionic Villous Sampling
2nd or 3rd Trimester Bleeding
Abdominal Trauma
Step 2 CK will often give scenarios like ectopic pregnancy, miscarriage, or trauma, and test if
you remember to give RhoGAM within 72 hours.
4. A Rh-negative woman presents to you with a ruptured ectopic pregnancy. How do you
determine the dose of RhoGAM in this patient?
➔ Kleihauer-Betke test ➞ Used to determine the dose of RhoGAM by measuring the
fetal RBCs in maternal serum
© 2025 TheMatchGuy LLC. All rights reserved. Page 3
, Note: a) Rosette test➞ Generally used to determine if the feto-maternal mixing of the
blood occurred (usually done before the Kleihauer-Betke test)
5. A 29F at 28 weeks' gestation comes to your clinic to establish care in January. Which
vaccination should she be provided at this visit?
➔ Tdap and Inactivated Influenza (Tdap ➞ 24-28 weeks of gestation, whereas an
inactivated influenza shot ➞ Can be given any time but generally given from October to April
every year.)
Note: a) Remember that live vaccines are contraindicated in:
Pregnant women
Children less than 1 year old (except rotavirus vaccine)
Immunosuppressed population (HIV and Organ transplant).
Live vaccines include MMR, Varicella, HPV, and live-attenuated influenza
y
b) Key USMLE Scenarios:
Tdap: Every pregnancy, ideally at 28 weeks
u
Influenza vaccine (inactivated): Every pregnancy during flu season
MMR/Varicella: Only postpartum if non-immune
G
Hep B vaccine: Safe during pregnancy if not previously vaccinated or high-risk
tch
6. A 22F has a history of hyperthyroidism. She is in her first trimester and consistently takes
antithyroid medications. If her medication is not stopped, what abnormality is the infant likely
a
to develop?
➔ Cutis Aplasia (caused by Methimazole)
e M
First trimester of pregnancy ➞ Manage hyperthyroidism with Propylthiouracil
Second and third trimesters of pregnancy ➞ Manage hyperthyroidism with methimazole
h
(propylthiouracil leads to hepatotoxicity in that period)
T Note: a) Here are some known teratogens and their potential effects:
© 2025 TheMatchGuy LLC. All rights reserved. Page 4
High Yield USMLE Step 2 CK Notes
Welcome to the Obstetrics and Gynecology High-Yield Notes for Step 2 CK.
These are the most commonly tested topics on the exam—ideal for quick review in your last
2 weeks before the exam, when you're short on time, or when you're just starting out and
want to focus on what is high yield. Created and peer-reviewed by physicians who scored
260+ on Step 2 CK in a Q&A style to reinforce active learning.
How to use this file
y
Read the question ➔ cover the answer ➔ self-quiz before revealing.
u
Review the NOTES ➔ they include high-yield details you don't want to
miss.
h G Need tutoring? Scan the QR code or visit The Match Guy Tutoring.
c
Don’t forget to watch the video lessons that go with this file. Learn
t
more here.
Ma
Prenatal Testing & Supplementation
The 1. A 35F 10 weeks gestation presents to you in her first trimester with elevated beta HCG,
decreased PAPP-A, and increased nuchal translucency. What's the diagnosis?
➔ Down syndrome (1st trimester infant + Elevated beta HCG + low PAPPA ➞ think Down
Syndrome)
Note: a) Other markers for Down syndrome (trisomy 21) include increased inhibin
levels, decreased estriol, and decreased AFP levels.
Trisomy B-HCG PAPPA AFP Inhibin Estriol
21 ⇑ ⇓ ⇓ ⇑ ⇓
18 ⇓ ⇓ ⇓ ⇓ or - ⇓
13 - - - - -
b) First-trimester screen is often part of non-invasive prenatal testing (NIPT) for early
aneuploidy risk assessment. If positive, next step ➞ do diagnostic testing ➞ CVS at 10–
13 weeks or amniocentesis at ≥15 weeks.
© 2025 TheMatchGuy LLC. All rights reserved. Page 1
Version 1.0 August 2025. No part of this document may be reproduced or distributed without written permission. For personal study only. Medical information
herein is for educational purposes and does not constitute clinical advice. Always confirm with current guidelines and your institution’s policies.
, Advanced maternal age (≥35 years) increases the risk of chromosomal anomalies ➞
these screens are especially important
c) Cell-free fetal DNA ➞ A highly useful test that can be used to detect fetal abnormalities
in <10 weeks of gestation. It is a non-invasive test with a very high sensitivity to detect
chromosomal abnormalities.
d) Remember that high AFP is indicative of abdominal wall defects, multiple gestations,
incorrect dating, and neural tube defects
2. A 22F presents to your clinic in her first trimester to establish care. She has an incomplete
history of childhood vaccinations. Which vaccine-preventable illness does she need to get
tested for?
➔ Rubella (Part of the MMR vaccine ➞ Live attenuated ➞ Contraindicated in pregnancy (if
Rubella IgG is negative, wait and vaccinate postpartum before you discharge the patient)
uy
Note: a) If she gets infected ➞ It can lead to Congenital Rubella Syndrome ➞ Triad of
Sensorineural hearing loss, Congenital cataracts, and Patent Ductus Arteriosus)
G
b) Several tests are recommended on the first prenatal visit. Here is a table you would
want to remember.
h
atc RhD Antigen/Antibody
Urine Culture
M
Urine dipstick for protein
For infections, you can use
e
HIV the following mnemonic:
“Hi (HIV), We (Varicella),
h
Chlamydia
aRe (Rubella), Happy
Initial Prenatal Visit
T Syphilis (VDRL/RPR) Babies (Hep B), and we will
Happily See (Hep C), the
Hep B (HbsAg) rainbow Colored
(Chlamydia) Sky (Syphilis).”
Hep C (Anti-HCV ab)
Rubella
Varicella
Hemoglobin/Hematocrit
Antibody Screen (if RhD
24-28 weeks negative)
1-hour 50g Glucose
tolerance test
Group B Streptococcus
36-38 weeks
Rectovaginal Culture
© 2025 TheMatchGuy LLC. All rights reserved. Page 2
, c) Asymptomatic bacteruria on urine culture ➞ Needs to be treated with a first-generation
cephalosporin or nitrofurantoin.
3. A 33F woman comes to you with severe right adnexal pain. On ultrasound, you find
ectopic pregnancy. Should this patient receive RhoGAM?
➔ Yes (Rho(D) immune globulin is given to Rh-negative mothers to prevent
alloimmunization from exposure to Rh-positive fetal red blood cells.)
Ectopic pregnancy, like any pregnancy loss or complication with potential fetomaternal
hemorrhage, can lead to maternal sensitization ➞ Administer RhoGAM prophylactically.)
Note: a) When NOT to Give RhoGAM:
The patient is Rh-positive
Father is confirmed Rh-negative (no Rh+ fetus possible)
The mother is already sensitized (Rh antibody screen positive) ➞ RhoGAM is not
effective at that point.
y
b) When to give RhoGAM:
u
If the mother is RhD-negative and has no RhD antibodies (i.e., antibody screen
negative).
h G
Indications for RhoGAM
tc
28-32 weeks of gestation
a
<72 hours after delivery
M
Ectopic pregnancy
e
Threatened Abortion
h
Hydatidiform mole
TAmniocentesis
Chorionic Villous Sampling
2nd or 3rd Trimester Bleeding
Abdominal Trauma
Step 2 CK will often give scenarios like ectopic pregnancy, miscarriage, or trauma, and test if
you remember to give RhoGAM within 72 hours.
4. A Rh-negative woman presents to you with a ruptured ectopic pregnancy. How do you
determine the dose of RhoGAM in this patient?
➔ Kleihauer-Betke test ➞ Used to determine the dose of RhoGAM by measuring the
fetal RBCs in maternal serum
© 2025 TheMatchGuy LLC. All rights reserved. Page 3
, Note: a) Rosette test➞ Generally used to determine if the feto-maternal mixing of the
blood occurred (usually done before the Kleihauer-Betke test)
5. A 29F at 28 weeks' gestation comes to your clinic to establish care in January. Which
vaccination should she be provided at this visit?
➔ Tdap and Inactivated Influenza (Tdap ➞ 24-28 weeks of gestation, whereas an
inactivated influenza shot ➞ Can be given any time but generally given from October to April
every year.)
Note: a) Remember that live vaccines are contraindicated in:
Pregnant women
Children less than 1 year old (except rotavirus vaccine)
Immunosuppressed population (HIV and Organ transplant).
Live vaccines include MMR, Varicella, HPV, and live-attenuated influenza
y
b) Key USMLE Scenarios:
Tdap: Every pregnancy, ideally at 28 weeks
u
Influenza vaccine (inactivated): Every pregnancy during flu season
MMR/Varicella: Only postpartum if non-immune
G
Hep B vaccine: Safe during pregnancy if not previously vaccinated or high-risk
tch
6. A 22F has a history of hyperthyroidism. She is in her first trimester and consistently takes
antithyroid medications. If her medication is not stopped, what abnormality is the infant likely
a
to develop?
➔ Cutis Aplasia (caused by Methimazole)
e M
First trimester of pregnancy ➞ Manage hyperthyroidism with Propylthiouracil
Second and third trimesters of pregnancy ➞ Manage hyperthyroidism with methimazole
h
(propylthiouracil leads to hepatotoxicity in that period)
T Note: a) Here are some known teratogens and their potential effects:
© 2025 TheMatchGuy LLC. All rights reserved. Page 4
