USMLE Step 1 Quiz: Reproductive Pathophysiology
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Reproductive PathophysiologyQuestion 1 of 20

A 17-year-old female is evaluated for primary amenorrhea. She has well-developed breasts, but scant axillary and pubic hair. Physical examination reveals a blind-ending vagina. A pelvic ultrasound shows no uterus or ovaries; testes are identified in the inguinal canal. Karyotype analysis reveals 46,XY. Serum testosterone levels are in the normal male range.

The clinical findings in this patient are best explained by a defect in which of the following?

Androgen receptors
5-alpha-reductase synthesis
Müllerian inhibiting factor secretion
Gonadotropin-releasing hormone (GnRH) pulse generation
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USMLE Step 1 Quiz

USMLE Step 1 Quiz: Reproductive Pathophysiology

Practice Reproductive Pathophysiology in USMLE Step 1 with focused quiz questions that help you check what you know, review explanations, and build confidence with test-style prompts.

What this quiz covers

This quiz focuses on Reproductive Pathophysiology, giving you a quick way to practice the rules, question types, and explanations that matter most for USMLE Step 1.

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Try each quiz question before looking at the correct answer. Use the explanations to review missed ideas, then come back to similar questions until the pattern feels familiar.

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Question 1

A 17-year-old female is evaluated for primary amenorrhea. She has well-developed breasts, but scant axillary and pubic hair. Physical examination reveals a blind-ending vagina. A pelvic ultrasound shows no uterus or ovaries; testes are identified in the inguinal canal. Karyotype analysis reveals 46,XY. Serum testosterone levels are in the normal male range.

The clinical findings in this patient are best explained by a defect in which of the following?

  1. Androgen receptors (correct answer)
  2. 5-alpha-reductase synthesis
  3. Müllerian inhibiting factor secretion
  4. Gonadotropin-releasing hormone (GnRH) pulse generation

Explanation: This patient has complete androgen insensitivity syndrome (AIS). A 46,XY genotype with testes that produce testosterone and Müllerian inhibiting factor (MIF) should result in a male phenotype. However, due to defective androgen receptors, testosterone and dihydrotestosterone cannot exert their effects, leading to the development of female external genitalia. MIF is produced normally, causing regression of Müllerian structures (uterus, fallopian tubes, upper vagina). The high testosterone is aromatized to estrogen, causing breast development.

Question 2

A 14-year-old individual, raised as a girl, is brought to the physician due to virilization at the onset of puberty. The patient has developed a deepening voice, clitoromegaly, and male-pattern muscle mass. Physical examination reveals a blind vaginal pouch and no palpable uterus. Karyotype is 46,XY. Further workup reveals normal testosterone levels but low dihydrotestosterone levels.

This patient's condition is caused by a deficiency in which of the following enzymes?

  1. Aromatase
  2. 17α-hydroxylase
  3. 21-hydroxylase
  4. 5-alpha-reductase (correct answer)

Explanation: This is a classic presentation of 5-alpha-reductase deficiency, an autosomal recessive disorder. This enzyme converts testosterone to the more potent dihydrotestosterone (DHT). In utero, a lack of DHT impairs the development of external male genitalia, leading to ambiguous or female-appearing genitalia. At puberty, the surge in testosterone is sufficient to cause virilization (masculinization).

Question 3

A 68-year-old man presents with a 6-month history of urinary frequency, nocturia, and a weak urinary stream. Digital rectal examination reveals a symmetrically enlarged, firm, and non-tender prostate. His serum prostate-specific antigen (PSA) level is within the normal range for his age. A biopsy is performed.

The pathologic process responsible for this patient's symptoms primarily involves hyperplasia of which prostatic zone?

  1. Peripheral zone
  2. Central zone
  3. Transitional zone (correct answer)
  4. Anterior fibromuscular stroma

Explanation: The patient's symptoms are characteristic of benign prostatic hyperplasia (BPH). BPH is a hormonally-driven proliferation of glandular and stromal elements that occurs almost exclusively in the periurethral and transitional zones of the prostate. This location explains the early onset of urinary obstruction symptoms. The peripheral zone is the most common site for prostatic adenocarcinoma.

Question 4

A 26-year-old woman presents with a 2-year history of irregular menstrual cycles, acne, and excessive facial hair growth. Her BMI is 31 kg/m². Laboratory studies show an elevated free testosterone level and a luteinizing hormone (LH) to follicle-stimulating hormone (FSH) ratio of 3:1. A pelvic ultrasound reveals bilateral enlarged ovaries with multiple small peripheral cysts.

Which of the following is considered a central pathophysiologic mechanism in this patient's condition?

  1. Primary adrenal hypercortisolism
  2. Autoimmune oophoritis
  3. Insulin resistance and hyperinsulinemia (correct answer)
  4. Pituitary prolactinoma

Explanation: This patient presents with classic features of Polycystic Ovary Syndrome (PCOS). A key pathophysiologic driver of PCOS is insulin resistance, leading to compensatory hyperinsulinemia. Insulin acts synergistically with LH to stimulate androgen production by ovarian theca cells. It also decreases hepatic production of sex hormone-binding globulin (SHBG), increasing the bioavailability of free androgens and contributing to hyperandrogenism.

Question 5

A 33-year-old nulligravid woman presents with debilitating pelvic pain that worsens during her menstrual periods. She also reports pain with intercourse and defecation. On pelvic examination, there is tenderness and nodularity in the posterior cul-de-sac (pouch of Douglas). Laparoscopy is performed and reveals dark, 'powder-burn' lesions on the pelvic peritoneum and ovaries.

The underlying pathophysiology of this patient's symptoms is the presence of which of the following?

  1. Ectopic endometrial glands and stroma (correct answer)
  2. Benign proliferation of myometrial smooth muscle
  3. Ascending infection of the upper genital tract
  4. Metastatic nests of ovarian adenocarcinoma

Explanation: This clinical presentation is classic for endometriosis, a condition characterized by the presence of endometrial tissue outside the uterine cavity. This ectopic tissue responds to cyclical hormonal changes, leading to bleeding, inflammation, adhesion formation, and pain (dysmenorrhea, dyspareunia, dyschezia). The 'powder-burn' lesions are characteristic findings.

Question 6

A 44-year-old woman presents with a 1-year history of heavy and prolonged menstrual bleeding. She also feels a sensation of pelvic pressure. Her hemoglobin is 9.5 g/dL. On bimanual examination, the uterus feels enlarged and irregular in contour, consistent with a 14-week gestation size. An ultrasound confirms the presence of multiple well-circumscribed, hypoechoic uterine masses.

These uterine masses are benign neoplasms arising from which of the following cell types?

  1. Endometrial glandular cells
  2. Myometrial smooth muscle cells (correct answer)
  3. Peritoneal mesothelial cells
  4. Cervical squamous epithelial cells

Explanation: The patient's presentation of menorrhagia, pelvic pressure, and an irregularly enlarged uterus is characteristic of uterine leiomyomas, also known as fibroids. These are the most common benign tumors in women and are composed of a monoclonal proliferation of myometrial smooth muscle cells.

Question 7

A 22-year-old woman, G1P0, at 14 weeks of gestation presents with vaginal bleeding and passage of grape-like vesicles. She has also experienced severe nausea and vomiting. Her uterus is enlarged to the size of a 20-week gestation. Her serum β-hCG level is markedly elevated at 450,000 mIU/mL. An ultrasound reveals a 'snowstorm' pattern with no fetus.

The most common genetic etiology for this condition is which of the following?

  1. Fertilization of an ovum by two sperm, resulting in a triploid karyotype
  2. Fertilization of an enucleated ovum by a single sperm that subsequently duplicates (correct answer)
  3. Trisomy of chromosome 18
  4. Maternal uniparental disomy

Explanation: This is a classic presentation of a complete hydatidiform mole. The most common cause (in about 90% of cases) is the fertilization of an anuclear (empty) ovum by a single haploid sperm, which then duplicates its chromosomes to form a diploid 46,XX karyotype containing only paternal DNA. Fertilization of an ovum by two sperm (dispermy) results in a triploid karyotype and is the cause of a partial mole, which typically involves a fetus.

Question 8

A 16-year-old girl is evaluated for short stature and primary amenorrhea. Physical examination reveals a webbed neck, a broad 'shield-like' chest with widely spaced nipples, and multiple nevi. Her ovaries are described as 'streak gonads' on pelvic imaging. Karyotype analysis is pending.

This patient is at an increased risk for which of the following cardiovascular malformations?

  1. Atrial septal defect
  2. Coarctation of the aorta (correct answer)
  3. Transposition of the great arteries
  4. Ventricular septal defect

Explanation: The patient's phenotype is highly suggestive of Turner syndrome (45,X). This condition is associated with a high incidence of congenital heart disease. The most common defects are a bicuspid aortic valve (seen in up to 30% of patients) and coarctation of the aorta (seen in about 10%). Coarctation is a narrowing of the aorta, typically just distal to the origin of the left subclavian artery.

Question 9

A 30-year-old man is evaluated for infertility. He is noted to be tall with disproportionately long legs. Physical examination reveals bilateral gynecomastia and small, firm testes. Laboratory studies are ordered.

Which of the following hormonal profiles would be most consistent with this patient's underlying condition?

  1. Low FSH, low LH, low testosterone
  2. High FSH, high LH, low testosterone (correct answer)
  3. Normal FSH, high LH, normal testosterone
  4. High FSH, normal LH, normal testosterone

Explanation: The patient's phenotype is classic for Klinefelter syndrome (47,XXY). The extra X chromosome leads to testicular dysgenesis, resulting in fibrosis of the seminiferous tubules and dysfunction of Leydig cells. This causes primary hypogonadism, characterized by low testosterone (from Leydig cell failure) and low inhibin B (from Sertoli cell/seminiferous tubule damage). The lack of negative feedback to the pituitary results in compensatory elevation of both FSH and LH.

Question 10

A 67-year-old woman presents with a 4-month history of abdominal bloating, early satiety, and a 10-lb unintentional weight loss. Physical examination reveals ascites and a palpable pelvic mass. A CT scan confirms a complex right adnexal mass with peritoneal studding.

An elevated serum level of which of the following tumor markers would be most specific for the likely diagnosis?

  1. Alpha-fetoprotein (AFP)
  2. Cancer antigen 125 (CA-125) (correct answer)
  3. Carcinoembryonic antigen (CEA)
  4. Lactate dehydrogenase (LDH)

Explanation: The patient's age and presentation with vague gastrointestinal symptoms, ascites, and an adnexal mass are highly suggestive of epithelial ovarian carcinoma. CA-125 is a protein expressed on the surface of these cancer cells and is used as a serum tumor marker to monitor disease progression and response to therapy. While not a perfect screening tool, it is elevated in over 80% of women with advanced epithelial ovarian cancer.

Question 11

A 45-year-old woman, G3P3, presents with a chief complaint of progressively severe menstrual pain and heavy menstrual bleeding. She describes the pain as a deep, cramping ache that persists throughout her period. On pelvic examination, the uterus is symmetrically enlarged, globular, and tender to palpation.

The pathophysiology of this patient's condition is best described as the presence of endometrial tissue within which of the following locations?

  1. Ovarian stroma
  2. Peritoneal cavity
  3. Myometrium (correct answer)
  4. Broad ligament

Explanation: This clinical picture of dysmenorrhea, menorrhagia, and a symmetrically enlarged, boggy, tender uterus is characteristic of adenomyosis. The underlying pathology is the presence of endometrial glands and stroma within the uterine myometrium. This leads to myometrial hypertrophy and hyperplasia, causing the uniform enlargement and symptoms.

Question 12

A 63-year-old woman presents with an episode of vaginal bleeding. Her last menstrual period was 11 years ago. Her medical history includes type 2 diabetes and hypertension, and she has a BMI of 36 kg/m². An endometrial biopsy is performed.

The development of the most likely malignancy in this patient is driven primarily by which of the following factors?

  1. Chronic anovulation
  2. Infection with HPV
  3. Unopposed estrogen stimulation (correct answer)
  4. Prior infection with Chlamydia

Explanation: Postmenopausal bleeding is a cardinal sign of endometrial carcinoma. The most common type (endometrioid adenocarcinoma) is associated with prolonged exposure to estrogen without the counteracting effects of progesterone. Obesity is a major risk factor because adipose tissue contains aromatase, which converts androgens to estrone (a type of estrogen), leading to chronic stimulation and hyperplasia of the endometrium, which can progress to carcinoma.

Question 13

A male infant is born at full term. On newborn examination, the left testis is descended in the scrotum, but the right testis is not palpable. An ultrasound confirms the presence of the right testis within the inguinal canal.

If this condition, known as cryptorchidism, is not surgically corrected, the patient will have a significantly increased lifetime risk of developing which of the following?

  1. Testicular torsion
  2. Inguinal hernia
  3. Germ cell tumor (correct answer)
  4. Epididymitis

Explanation: Cryptorchidism is the failure of one or both testes to descend into the scrotum. The higher temperature outside the scrotum impairs spermatogenesis and increases the risk of malignant transformation. The lifetime risk of developing a testicular germ cell tumor (most commonly seminoma) in an undescended testis is approximately 3 to 5 times higher than in a normally descended testis. Surgical correction (orchiopexy) reduces this risk but does not eliminate it entirely.

Question 14

A 34-year-old woman presents with a 9-month history of amenorrhea. She also reports experiencing hot flashes, night sweats, and vaginal dryness. She has no desire for pregnancy at this time. Her past medical history is unremarkable. A pregnancy test is negative.

Which of the following sets of hormone levels is most likely to be found in this patient?

  1. Decreased FSH, decreased LH, decreased estradiol
  2. Increased FSH, increased LH, decreased estradiol (correct answer)
  3. Normal FSH, normal LH, decreased progesterone
  4. Increased prolactin, normal TSH, normal FSH

Explanation: This patient's presentation of secondary amenorrhea with menopausal symptoms before the age of 40 is consistent with primary ovarian insufficiency (premature ovarian failure). This is a form of hypergonadotropic hypogonadism. The ovaries cease to function properly, leading to a profound decrease in estradiol production. The loss of negative feedback from estradiol on the pituitary gland results in a compensatory increase in both FSH and LH levels.

Question 15

A 25-year-old woman presents with hemoptysis and dyspnea 4 months after a suction curettage for a hydatidiform mole. Her serum β-hCG level is 200,000 mIU/mL. A chest radiograph reveals multiple, bilateral, well-circumscribed nodules.

The pulmonary findings in this patient are the result of a malignancy that has a strong propensity for which type of metastatic spread?

  1. Hematogenous (correct answer)
  2. Lymphatic
  3. Direct extension
  4. Transcoelomic

Explanation: This patient has developed choriocarcinoma, a malignant neoplasm of trophoblastic cells, as a complication of her molar pregnancy. Choriocarcinoma is characterized by its aggressive nature and tendency for early hematogenous spread. The malignant cells invade the uterine vasculature and embolize to distant sites, most commonly the lungs. This results in the characteristic 'cannonball' metastases seen on chest imaging and can cause symptoms like hemoptysis and dyspnea.

Question 16

A 15-year-old boy is brought to the emergency department with a 3-hour history of sudden, severe left testicular pain that began during a soccer match. He also reports nausea. On examination, the left testis is swollen, exquisitely tender, and positioned high in the scrotum with a horizontal lie. The cremasteric reflex is absent on the left side.

This urologic emergency is most commonly predisposed by which of the following underlying abnormalities?

  1. Patent processus vaginalis
  2. Inadequate fixation of the testis to the tunica vaginalis (correct answer)
  3. Dilatation of the pampiniform plexus
  4. Congenital obstruction of the ejaculatory duct

Explanation: Testicular torsion occurs when the spermatic cord twists, cutting off blood supply to the testis. The most common predisposing factor is a congenital anomaly known as the 'bell clapper' deformity, where the tunica vaginalis has an abnormally high attachment to the spermatic cord. This allows the testis to rotate freely within the tunica vaginalis, leading to torsion. A patent processus vaginalis leads to hydroceles or indirect inguinal hernias. Dilatation of the pampiniform plexus is a varicocele.

Question 17

A 29-year-old man presents with a painless right testicular mass he discovered a month ago. He has no other symptoms. Ultrasound confirms a solid, well-circumscribed, hypoechoic mass confined to the testis. An orchiectomy is performed, and pathology reveals large cells with clear cytoplasm and prominent nucleoli arranged in lobules separated by fibrous septa with lymphocytic infiltrate.

This tumor, the most common type of testicular cancer, originates from which cell line?

  1. Germ cells (correct answer)
  2. Leydig cells
  3. Sertoli cells
  4. Stromal cells

Explanation: The clinical presentation and histopathology are classic for a seminoma, which is the most common type of testicular germ cell tumor. Testicular cancers are broadly divided into germ cell tumors (95%) and sex cord-stromal tumors. Seminomas arise from the malignant transformation of primordial germ cells or spermatogonia. Leydig and Sertoli cell tumors are much rarer sex cord-stromal tumors.

Question 18

A 28-year-old woman with a history of pelvic inflammatory disease presents to the emergency department with sudden-onset, severe right lower quadrant pain and vaginal spotting. Her last menstrual period was 7 weeks ago. A urine pregnancy test is positive. Her serum β-hCG is 1,500 mIU/mL. A transvaginal ultrasound does not show an intrauterine gestational sac.

In this condition, the embryo has most likely implanted in which location?

  1. Isthmus of the fallopian tube
  2. Cornual region of the uterus
  3. Ampulla of the fallopian tube (correct answer)
  4. Cervix

Explanation: This patient has a suspected ectopic pregnancy. The most common site of implantation for an ectopic pregnancy is the fallopian tube (over 95% of cases), and within the tube, the ampulla is the most frequent location (about 70-80%). This is because fertilization normally occurs in the ampulla, and any factor that delays transport of the embryo to the uterus, such as scarring from prior PID, increases the risk of implantation there.

Question 19

A 23-year-old sexually active woman presents to the emergency department with a 3-day history of lower abdominal pain, fever, and a malodorous vaginal discharge. On physical examination, her temperature is 38.6°C (101.5°F). There is bilateral adnexal tenderness and significant cervical motion tenderness ('chandelier sign').

This condition, if left untreated, is most likely to cause which of the following long-term complications?

  1. Endometrial cancer
  2. Uterine prolapse
  3. Tubal factor infertility (correct answer)
  4. Vesicovaginal fistula

Explanation: The patient has pelvic inflammatory disease (PID), an infection of the upper female genital tract. The infection and subsequent inflammation can cause scarring and adhesions within the fallopian tubes (salpingitis), leading to tubal obstruction. This significantly increases the risk of future ectopic pregnancy and tubal factor infertility.

Question 20

A 48-year-old woman presents with postcoital vaginal bleeding. She has not had a Pap smear in over 10 years. A cervical biopsy confirms invasive squamous cell carcinoma. Molecular analysis of the tumor tissue reveals the presence of human papillomavirus (HPV) type 16 DNA.

The oncogenic potential of this virus is primarily mediated by viral proteins that interfere with the function of which of the following host cell proteins?

  1. p53 and Rb (correct answer)
  2. BRCA1 and BRCA2
  3. APC and β-catenin
  4. RAS and MYC

Explanation: High-risk HPV strains, such as HPV 16 and 18, are the primary cause of cervical cancer. Their oncogenic effects are mainly due to the viral proteins E6 and E7. The E6 protein binds to the p53 tumor suppressor protein, targeting it for degradation. The E7 protein binds to and inactivates the retinoblastoma (Rb) tumor suppressor protein. This disruption of two critical cell cycle checkpoints promotes uncontrolled cell proliferation.