10 USMLE OB/GYN Questions with Answers and Explanations (Set 1)

These 10 USMLE obstetrics and gynecology practice questions cover cases that are tested again and again: eclampsia, ectopic pregnancy, intrahepatic cholestasis of pregnancy, shoulder dystocia with Erb palsy, postpartum thyroiditis, PCOS, endometrial cancer, third-trimester bleeding, puerperal sepsis and breastfeeding problems. Each question includes the correct answer and an explanation.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. A 16-year-old girl is brought to the emergency room by her mother following a seizure. She is 30-week pregnant with twins. Her mother told you that her daughter was eating lunch and when she stood up she fell on the floor and started shaking. She never had any seizures before. During last week, she complained of headache and swelling of her face. She missed her last two obstetrician’s appointments. On Examination, she is unresponsive and difficult to arouse. Her blood pressure is 210/120. There is edema of her face and both hands. Fetal heart rate is 140/min. What is the next step of management for this patient?

A- Hospitalization and treatment with antihypertensive and epileptic drugs and wait until delivery at term
B- Hospitalization and observation until delivery at term
C- Hospitalization and induction of labor
D- Outpatient treatment and recommend regular visits to the clinic

This pregnant woman has eclampsia. It is diagnosed clinically and characterized by seizures which differentiate it from pre-eclampsia. Delivery is the only cure for eclampsia. After the mother is stabilized with magnesium sulfate (to prevent more seizures) and antihypertensives, delivery should follow. Induction of labor is preferred unless there are contraindications (e.g., non-reassuring fetal status or maternal instability requiring cesarean).
Other options will lead to danger to both mother and child.
The correct answer is C

 

Question 2. A 23-year-old woman presents to the emergency room with severe lower right abdominal pain for the last six hours. She had intermittent lower abdominal pain for three days but never been severe like this time. Her last menstrual period was seven weeks ago and before that she had regular 28-day periods. On physical examination, her vital signs are within normal limits and she has a local tenderness on the lower abdomen with no rebound. On pelvic examination, there is a tender small-sized mass felt in the right vaginal fornix. What is the most likely diagnosis?

A- Acute appendicitis
B- Ovarian cyst
C- Ectopic pregnancy
D- Endometriosis
E- Pelvic abscess

Missed periods in a woman of reproductive age suggest pregnancy. Lower abdominal pain with a tender adnexal mass in early pregnancy is ectopic pregnancy until proven otherwise. The next steps are a quantitative beta-hCG and a transvaginal ultrasound.
The correct answer is C

 

Question 3. A 25-year-old woman presents to her physician at 28 weeks of gestation with general itching for one week. Itching is worse at night and more pronounced on the soles and palms. She has no history of allergy or dermatological diseases. She is compliant with regular examinations, and her pregnancy is uncomplicated. Her physical and obstetric examinations are unremarkable. Laboratory tests reveal normal full blood count, renal function tests, and blood coagulation tests. Her liver function tests are as follows: ALT 47 IU/L AST 55 IU/L Alkaline phosphatase 356 IU/L Total bilirubin 1.9 Bile acids 15 micromol/L Serology for hepatitis is negative What is the best treatment for this woman’s itching?

A- Hospitalization and induction of labor
B- Ursodeoxycholic acid and vitamin K
C- Diphenhydramine
D- No treatment and repeat liver function tests in a week

Ursodeoxycholic acid improves bile flow, lowers bile acid levels, and reduces fetal risks. Vitamin K supplementation corrects potential deficiency due to malabsorption from cholestasis. Delivery is typically considered around 37–38 weeks to reduce risk of stillbirth.
Correct answer is B

 

Question 4. A 32-year-old diabetic woman delivered a large baby after difficult vaginal delivery. At labor, the head emerged first and then the shoulders were stuck behind the bony pelvis. The obstetrician had to use some tools and maneuvers to deliver the baby. The baby had a good cry and red pink color but his right arm was not moving. It was hanging on his side with medial rotation. Which of these nerve roots are most likely affected?

A- C5 and C6
B- C6 and C7
C- C7 and C8
D- C8 and T1

Shoulder dystocia is a condition characterized by difficulty to deliver shoulder of the baby after delivery of the head. There are some maneuvers used by the obstetrician to deliver it safely. Some complications could happen during manual delivery of the shoulder. Brachial plexus injury, fetal hypoxia and even fetal death are complications of these maneuvers. This case presentation represents Erb’s palsy which caused by injury to C5 and C6. The right arm is hanging by the side with medial rotation, a classic “waiter’s tip” posture characteristic of Erb’s palsy.
The correct answer is A

 

Question 5. A 27 year-old woman presents to the clinic complaining of fatigue and constipation. She also notes recent cold intolerance and dry skin. Her obstetric history is significant for a full term vaginal delivery 6 months ago. Her past medical history is unremarkable except for fine tremors and mild palpitations 3 months ago that resolved spontaneously. On examination, her temperature is 97.3 F, her pulse is 54/min, her blood pressure is 120/80 and her thyroid gland is enlarged and not tender. Her thyroid panel shows low T4 and elevated TSH. What is the most likely effective treatment of this condition?

A- Levothyroxine for 6–12 months, then reassess
B- Life-long levothyroxine
C- Surgery and life-long levothyroxine
D- Begin methimazole therapy
E- Begin radioactive iodine

This is postpartum thyroiditis: a short hyperthyroid phase (fine tremors and palpitations 3 months ago) followed by a hypothyroid phase. Because she is symptomatic (fatigue, constipation, cold intolerance, bradycardia), she should receive levothyroxine for 6 to 12 months, then it is tapered and thyroid function is rechecked. Most women recover normal thyroid function, so life-long treatment, surgery, methimazole and radioactive iodine are not indicated.
The correct answer is A

 

Question 6. A 32-year-old woman with a long history of irregular menstrual periods visits her physician for consultation. She is married for 8 years and has been unable to conceive. Her menstrual period occurs once every 2-4 months. She had normal Pap smear last year. Her height is 5 feet 2 inches. Her weight is 205 pounds. Her vital signs are within normal limits. She has acne and excessive facial hair. This patient is at risk of which one of the following diseases?

A- Lung cancer
B- Cervical cancer
C- Ovarian cancer
D- Endometrial cancer
E- Liver cirrhosis

This patient most likely has polycystic ovarian syndrome (PCOS) which is characterized by infertility, oligomenorrhea, obesity and hirsutism. Lack of menstrual cycles due to failure of ovulation leads to low level of progesterone and unopposed estrogen. Prolonged exposure of unopposed estrogen put this woman at high risk of endometrial cancer.
The correct answer is D

 

Question 7. A 57-year-old woman presents to the clinic with a complaint of abnormal uterine bleeding. A biopsy is taken for evaluation of endometrial cancer. At which stage is endometrial cancer most often diagnosed?

A- I
B- II
C- III
D- IV

Endometrial cancer is often diagnosed at early stage due to abnormal vaginal bleeding which prompts patients to see their doctors. It usually occurs in the postmenopausal women and those who take estrogen-only hormone replacement therapy. So women who have not had a hysterectomy should not be taking estrogen-only hormone replacement therapy.
The correct answer is A

 

Question 8. A 22-year-old G2P1 at 28 weeks gestation presents to the emergency room with heavy vaginal bleeding. Which of the following is NOT recommended as the next step of action?

A- Admit the patient
B- Digital pelvic examination
C- Stabilize the patient
D- Ultrasound examination of the pelvis

Digital pelvic examination is contraindicated unless the ultrasound of the pelvis rules out placenta previa. The patient should be admitted and stabilized. Management should be directed according to the results of further workup.
The correct answer is B

 

Question 9. A 28-year-old woman with a history of normal delivery 3 days ago after an uneventful pregnancy is admitted to the ICU because of high fever and foul-smelling vaginal discharge. General examination reveals temperature of 103.3 F, pulse 96/min and blood pressure 100/70 mmHg. Pelvic examination reveals bloody yellowish discharge and dilated, enlarged and bulky cervix. What is the next step of action?

A- Blood samples and intravenous antibiotics
B- CT scans of the abdomen and pelvis
C- Observation and waiting for the results of blood culture
D- Oral ampicillin and gentamicin
E- MRI of the pelvis

This is a case of puerperal sepsis which is also known as postpartum infection. Predisposing factors are delivery by cesarean section (CS), premature rupture of membranes, and presence of group B-Streptococci in the vagina. Prolonged labor and manual removal of the placenta can lead to postpartum infections. Blood samples and vaginal discharge for culture should be collected before intravenous antibiotics to determine the causative organism and antibiotic sensitivity. Oral antibiotics are not recommended for high fever like this one. Image studies, if needed, should be done later after initiation of therapy. Observation and waiting for the results of blood culture are inappropriate in this case.
The correct answer is A

 

Question 10. A 23-year-old woman presents to the clinic with a complaint of pain in her left breast since last night. She is breastfeeding her 1-week-old girl. On examination, her temperature is 99.8 F, her pulse is 88/min. and her blood pressure is 120/80. Local examination of the left breast reveals a localized soft tender 1-inch area. Her past medical, surgical and family histories are unremarkable. What is the most likely diagnosis?

A- A clogged milk duct
B- A breast abscess
C- Milk engorgement
D- Mastitis
E- Inflammatory carcinoma

This is a presentation of a clogged milk duct in which the mass is localized, tender, and not erythematous or firm. There is no fever or any signs of acute inflammation. There is also no signs or family history of cancer. Abscess occurs later if this mass is infected and no treatment applied. Milk engorgement results in generalized involvement of both breasts. A clogged milk duct is diagnosed mainly by exclusion.
The correct answer is A

 

High-yield points from this set

  • Seizures with severe hypertension in pregnancy = eclampsia: magnesium sulfate, blood pressure control, then delivery.
  • Missed period + pelvic pain + adnexal mass = ectopic pregnancy until proven otherwise.
  • Itching of palms and soles in the third trimester with high bile acids = intrahepatic cholestasis of pregnancy (ursodeoxycholic acid).
  • Shoulder dystocia with an arm hanging in internal rotation = Erb palsy (C5–C6).
  • Hyperthyroid phase followed by hypothyroid phase after delivery = postpartum thyroiditis.
  • PCOS causes unopposed estrogen and raises the risk of endometrial cancer.
  • Endometrial cancer is usually found at stage I because postmenopausal bleeding brings women in early.
  • Never do a digital pelvic exam in third-trimester bleeding until ultrasound rules out placenta previa.
  • Fever and foul lochia days after delivery = puerperal infection: cultures and IV antibiotics.
  • A tender localized breast lump without fever in a nursing mother = clogged milk duct.

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