A 39-year-old G3P0 woman presents for preconception counseling and evaluation. The patient’s past medical history reveals hypertension and type 1 diabetes. She is currently on an insulin pump and medications for hypertension including labetalol. Her blood pressure is 130/85 mm Hg; pulse, 76/min; and BMI, 26 kg/m2. Her most recent HbA1c is 6.5%. Her previous pregnancies ended in spontaneous abortion during the 1st trimester despite adequate prenatal care. The patient intends to have a healthy pregnancy and desires to learn more about the risk factors that potentially trigger miscarriage. Which of the following maternal risk factors is most likely associated with early pregnancy loss?
Q232
A 17-year-old girl is being evaluated for primary amenorrhea. A pelvic ultrasound shows no uterus, fallopian tubes, or ovaries, despite having normal external sexual organs. On physical examination, there is no axillary or pubic hair, and breast development is normal. The laboratory tests show evidence of increased serum testosterone with normal conversion to dihydrotestosterone (DHT) and increased luteinizing hormone (LH). What is the karyotype of this patient?
Q233
A 23-year-old female presents to the emergency department with right lower abdominal pain that began suddenly one hour ago. She is writhing in discomfort and has vomited twice since arrival. She has no chronic medical conditions, but states she has had chlamydia two or three times in the past. Her abdomen is firm, and she is guarding. Pelvic exam reveals blood pooling in the vagina and right adnexal tenderness. Her last menstrual period was 7 weeks ago. A pregnancy test is positive.
Which of the following is an appropriate next step in diagnosis?
Q234
A 31-year-old female presents to her gynecologist with spotting between periods. She reports that her menses began at age 11, and she has never had spotting prior to the three months ago. Her medical history is significant for estrogen-receptor positive intraductal carcinoma of the breast, which was treated with tamoxifen. An endometrial biopsy is performed, which shows endometrial hyperplasia with atypia. She reports that she and her husband are currently trying to have children. What is the next best step?
Q235
A 25-year-old nulliparous woman presents to her gynecologist complaining of recurrent menstrual pain. She reports a 4-month history of pelvic pain that occurs during her periods. It is more severe than her typical menstrual cramps and sometimes occurs when she is not on her period. She also complains of pain during intercourse. Her periods occur every 28-30 days. Her past medical history is notable for kyphoscoliosis requiring spinal fusion and severe acne rosacea. She takes tretinoin and has a copper intra-uterine device. Her family history is notable for ovarian cancer in her mother and endometrial cancer in her paternal grandmother. Her temperature is 99°F (37.2°C), blood pressure is 120/85 mmHg, pulse is 90/min, and respirations are 16/min. On exam, she appears healthy and is in no acute distress. A bimanual examination demonstrates a normal sized uterus and a tender right adnexal mass. Her intrauterine device is well-positioned. What is the underlying cause of this patient's condition?
Q236
One day after doctors helped a 28-year-old primigravid woman deliver a 4700 g (10 lb 6 oz) boy, he has bluish discoloration of his lips and fingernails. Oxygen saturation on room air is 81%. Examination shows central cyanosis. A continuous machine-like murmur is heard over the left upper sternal border. A single S2 heart sound is present. Supplemental oxygen does not improve the cyanosis. Echocardiography shows the pulmonary artery arising from the posterior left ventricle and the aorta arising from the right ventricle with active blood flow between the right and left ventricles. Further evaluation of the mother is most likely to show which of the following?
Q237
A 64-year-old nulliparous woman comes to the physician because of fatigue and an increase in abdominal girth despite a 5-kg (11.0-lb) weight loss over the past 6 months. Her last Pap smear 2 years ago showed atypical squamous cells of undetermined significance; subsequent HPV testing was negative at that time. Menarche was at the age of 10 years and her last menstrual period was 6 years ago. Abdominal examination shows shifting dullness. There is tenderness to palpation of the left lower quadrant but no guarding or rebound. Bimanual palpation shows a small uterus and a left adnexal mass. Further evaluation of this patient is most likely to show which of the following findings?
Q238
A 17-year-old girl presents to the gynecologist's office due to lack of menarche. She has been sexually active with 1 male lifetime partner and always uses a condom. Her mother believes that breast development started at 11 years old. On exam, she is a well-appearing, non-hirsute teenager with Tanner V breast and pubic hair development. Her pelvic exam reveals normal external genitalia, a shortened vagina, and the cervix is unable to be visualized. Initial laboratory testing for hormone levels and karyotype is normal, and imaging confirms what you suspect on exam. What is the most likely cause of her lack of menstruation?
Q239
A 2250-g (5.0-lb) male newborn and a 2900-g (6.4-lb) male newborn are delivered at 36 weeks' gestation to a 24-year-old, gravida 1, para 1 woman. The mother had no prenatal care. Examination of the smaller newborn shows low-set ears, retrognathia, and right-sided clubfoot. The hematocrit is 41% for the smaller newborn and 69% for the larger newborn. This pregnancy was most likely which of the following?
Q240
A 16-year-old girl presents with primary amenorrhea. On exam, you note that she is short and has a shield chest. You order abdominal imaging, which suggests the presence of streak gonads.
Of the choices listed below, which of the following karyotypes is possible in this patient?
I: 45,XO
II: 45,XO/46,XX mosaicism
III: 46,X,del(Xp) or other structural X abnormalities
High-risk pregnancies US Medical PG Practice Questions and MCQs
Question 231: A 39-year-old G3P0 woman presents for preconception counseling and evaluation. The patient’s past medical history reveals hypertension and type 1 diabetes. She is currently on an insulin pump and medications for hypertension including labetalol. Her blood pressure is 130/85 mm Hg; pulse, 76/min; and BMI, 26 kg/m2. Her most recent HbA1c is 6.5%. Her previous pregnancies ended in spontaneous abortion during the 1st trimester despite adequate prenatal care. The patient intends to have a healthy pregnancy and desires to learn more about the risk factors that potentially trigger miscarriage. Which of the following maternal risk factors is most likely associated with early pregnancy loss?
A. Infection
B. Hypercoagulable state
C. Diabetes
D. Chronic hypertension
E. Age (Correct Answer)
Explanation: ***Age***
- **Maternal age** is a significant risk factor for aneuploidy, which is the leading cause of early pregnancy loss.
- As women age, the quality of their oocytes declines, increasing the risk of chromosomal abnormalities.
*Infection*
- While certain **infections** (e.g., toxoplasmosis, rubella, cytomegalovirus, herpes simplex) can cause miscarriage, they are less common causes of recurrent early pregnancy loss than chromosomal abnormalities.
- Infections would typically present with other systemic symptoms or specific laboratory findings, which are not mentioned here.
*Hypercoagulable state*
- **Hypercoagulable states** (e.g., antiphospholipid syndrome) are known causes of recurrent pregnancy loss, particularly in the second and third trimesters, but also in early pregnancy.
- However, for general early pregnancy loss, advanced maternal age leading to aneuploidy is a more common and direct risk factor.
*Diabetes*
- Poorly controlled **diabetes** (especially with HbA1c >8%) is a significant risk factor for miscarriage and congenital anomalies.
- This patient's HbA1c of 6.5% indicates reasonably good control, reducing the likelihood of diabetes being the primary sole cause for her recurrent losses.
*Chronic hypertension*
- **Chronic hypertension** is associated with an increased risk of preeclampsia, fetal growth restriction, and stillbirth, especially in later trimesters.
- While it can contribute to adverse pregnancy outcomes, it is not the most common direct cause of **early pregnancy loss,** particularly in the first trimester.
Question 232: A 17-year-old girl is being evaluated for primary amenorrhea. A pelvic ultrasound shows no uterus, fallopian tubes, or ovaries, despite having normal external sexual organs. On physical examination, there is no axillary or pubic hair, and breast development is normal. The laboratory tests show evidence of increased serum testosterone with normal conversion to dihydrotestosterone (DHT) and increased luteinizing hormone (LH). What is the karyotype of this patient?
A. 47, XXY
B. 45, X0
C. 46, XX
D. 46, XY (Correct Answer)
E. 47, XXX
Explanation: ***46, XY***
- This patient presents with **complete androgen insensitivity syndrome (CAIS)**. Despite having a **46, XY karyotype** (genetically male), the body's cells are unable to respond to androgens.
- While genetically male, the lack of androgen action prevents the development of male internal and external genitalia, leading to the development of **female external genitalia** and **normal breast development** due to estrogen action (from androgen aromatization) but no uterus, fallopian tubes, or ovaries. The **absence of axillary and pubic hair** (secondary sex characteristics dependent on androgens) further supports CAIS, along with high testosterone and LH.
*47, XXY*
- This karyotype corresponds to **Klinefelter syndrome**, a condition in which individuals are genetically male with an extra X chromosome.
- Individuals with Klinefelter syndrome typically present with **hypogonadism**, **gynecomastia**, and are phenotypically male, often with small testes and infertility. They would not present with female external genitalia or absent internal female organs as described.
*45, X0*
- This karyotype describes **Turner syndrome**, characterized by the absence of one X chromosome, typically resulting in a female phenotype.
- Patients with Turner syndrome usually present with **primary amenorrhea**, **streak gonads**, **short stature**, and **lack of breast development** (due to ovarian failure), which contradicts the normal breast development seen in this patient.
*46, XX*
- This is the normal female karyotype. A patient with this karyotype would typically have **normal female internal and external genitalia**, including a uterus, fallopian tubes, and ovaries.
- The absence of a uterus, fallopian tubes, and ovaries in this patient, along with normal breast development but absent axillary/pubic hair, rules out a normal female karyotype.
*47, XXX*
- This karyotype refers to **Triple X syndrome**, which typically results in a female phenotype.
- Women with Triple X syndrome are often phenotypically normal and fertile, although some may experience **learning difficulties** or **mild developmental delays**. They would generally have **normal female internal and external reproductive organs**, which is contrary to the findings in this case.
Question 233: A 23-year-old female presents to the emergency department with right lower abdominal pain that began suddenly one hour ago. She is writhing in discomfort and has vomited twice since arrival. She has no chronic medical conditions, but states she has had chlamydia two or three times in the past. Her abdomen is firm, and she is guarding. Pelvic exam reveals blood pooling in the vagina and right adnexal tenderness. Her last menstrual period was 7 weeks ago. A pregnancy test is positive.
Which of the following is an appropriate next step in diagnosis?
A. Methotrexate and discharge with strict follow-up instructions.
B. Exploratory laparotomy
C. Dilation and curettage
D. Transvaginal ultrasound (Correct Answer)
E. Transabdominal ultrasound
Explanation: ***Transvaginal ultrasound***
- A **transvaginal ultrasound** is the most appropriate next step given the **positive pregnancy test**, significant abdominal pain, and adnexal tenderness, strongly suggesting an **ectopic pregnancy** that needs urgent confirmation and localization.
- This imaging modality provides the **highest resolution** for visualizing the uterus, adnexa, and assessing for an intrauterine pregnancy or extrauterine gestational sac or free fluid in the pelvis, which are critical for diagnosis and management.
*Methotrexate and discharge with strict follow-up instructions.*
- While methotrexate is a treatment for stable ectopic pregnancies, it is not an appropriate next step in diagnosis, and administering it without definitive diagnostic imaging is **premature and potentially harmful**.
- The patient's **acute presentation** with severe pain, vomiting, signs of peritoneal irritation (guarding, firm abdomen), and suspected vaginal bleeding indicates a potentially **ruptured or unstable ectopic pregnancy**, which mandates immediate diagnostic confirmation and likely surgical intervention, not medical management and discharge.
*Exploratory laparotomy*
- **Exploratory laparotomy** is a surgical intervention, not a diagnostic step to be performed before confirming the nature and location of the suspected ectopic pregnancy.
- While it may be necessary if the patient is **hemodynamically unstable** or if a ruptured ectopic pregnancy is strongly suspected and unable to be confirmed by less invasive means, diagnostic imaging should precede it in a relatively stable patient.
*Dilation and curettage*
- **Dilation and curettage (D&C)** is a procedure performed to remove tissue from the uterus, typically for an incomplete miscarriage or uterine pathology.
- Given the strong suspicion of an **ectopic pregnancy** (pregnancy outside the uterus), a D&C would not address the extrauterine pregnancy and could delay appropriate diagnosis and management.
*Transabdominal ultrasound*
- A **transabdominal ultrasound** can visualize pelvic structures but has **lower resolution** for early pregnancy and adnexal pathology compared to a transvaginal ultrasound.
- In a patient with suspected ectopic pregnancy and acute symptoms, the **superior detail** provided by a transvaginal ultrasound is crucial for accurate and timely diagnosis.
Question 234: A 31-year-old female presents to her gynecologist with spotting between periods. She reports that her menses began at age 11, and she has never had spotting prior to the three months ago. Her medical history is significant for estrogen-receptor positive intraductal carcinoma of the breast, which was treated with tamoxifen. An endometrial biopsy is performed, which shows endometrial hyperplasia with atypia. She reports that she and her husband are currently trying to have children. What is the next best step?
A. Start progestin-only therapy (Correct Answer)
B. Partial, cervix-sparing hysterectomy
C. Observation with annual endometrial biopsies
D. Start combination estrogen and progestin therapy
E. Total abdominal hysterectomy with bilateral salpingo-oophorectomy
Explanation: ***Start progestin-only therapy***
- This patient has **endometrial hyperplasia with atypia**, which carries a high risk of progression to **endometrial cancer**, especially when associated with **tamoxifen use**.
- Given her desire for **fertility preservation**, **high-dose progestin therapy** (e.g., megestrol acetate, medroxyprogesterone acetate) is the **first-line treatment** to reverse the hyperplasia while allowing for potential conception.
*Partial, cervix-sparing hysterectomy*
- This procedure treats the uterus but would still preclude future pregnancies and is typically reserved for cases where definitive surgical management is required but the patient wishes to preserve vaginal function.
- It would be too aggressive for a patient desiring fertility who has not failed medical therapy, and it does not remove the at-risk endometrium effectively.
*Observation with annual endometrial biopsies*
- **Endometrial hyperplasia with atypia** has a significant risk of progressing to **endometrial carcinoma**, estimated at 29% over 20 years.
- Simply observing without intervention is **inappropriate** given this high risk, even with regular monitoring.
*Start combination estrogen and progestin therapy*
- The patient's endometrial hyperplasia is likely due to the **unopposed estrogenic effect of tamoxifen** on the endometrium, which acts as a selective estrogen receptor modulator (SERM).
- Adding **estrogen** would exacerbate the problem and increase the risk of endometrial cancer, making this an unsafe and inappropriate treatment.
*Total abdominal hysterectomy with bilateral salpingo-oophorectomy*
- This is a definitive surgical treatment for endometrial hyperplasia with atypia and endometrial cancer, and would effectively remove the affected tissue.
- However, this option would render the patient **infertile**, which contradicts her expressed desire to have children. It would be considered if progestin therapy fails or if fertility is not a concern.
Question 235: A 25-year-old nulliparous woman presents to her gynecologist complaining of recurrent menstrual pain. She reports a 4-month history of pelvic pain that occurs during her periods. It is more severe than her typical menstrual cramps and sometimes occurs when she is not on her period. She also complains of pain during intercourse. Her periods occur every 28-30 days. Her past medical history is notable for kyphoscoliosis requiring spinal fusion and severe acne rosacea. She takes tretinoin and has a copper intra-uterine device. Her family history is notable for ovarian cancer in her mother and endometrial cancer in her paternal grandmother. Her temperature is 99°F (37.2°C), blood pressure is 120/85 mmHg, pulse is 90/min, and respirations are 16/min. On exam, she appears healthy and is in no acute distress. A bimanual examination demonstrates a normal sized uterus and a tender right adnexal mass. Her intrauterine device is well-positioned. What is the underlying cause of this patient's condition?
A. Endometrial glands and stroma within the uterine myometrium
B. Excess androgen production
C. Endometrial glands and stroma within the peritoneal cavity (Correct Answer)
D. Benign proliferation of uterine myometrium
E. Chronic inflammation of the uterine endometrium
Explanation: ***Endometrial glands and stroma within the peritoneal cavity***
- This describes **endometriosis**, characterized by **dysmenorrhea, dyspareunia, and chronic pelvic pain** which are all present in this patient.
- The presence of a **tender adnexal mass** further supports endometriosis, likely an **endometrioma** (chocolate cyst).
*Endometrial glands and stroma within the uterine myometrium*
- This condition is known as **adenomyosis**, and typically presents with **symmetrical, boggy, enlarged uterus** and heavy menstrual bleeding.
- This patient's uterus is described as **normal sized**, making adenomyosis less likely.
*Excess androgen production*
- This is characteristic of **Polycystic Ovarian Syndrome (PCOS)**, which presents with hirsutism, acne, irregular periods, and infertility.
- The patient's symptoms of regular but painful periods, dyspareunia, and chronic pelvic pain are not typical for PCOS.
*Benign proliferation of uterine myometrium*
- This describes **uterine fibroids (leiomyomas)**, which are common and can cause heavy menstrual bleeding, pelvic pressure, and infertility.
- While they can cause pain, the clinical picture of dysmenorrhea, dyspareunia, and a tender adnexal mass is more consistent with endometriosis.
*Chronic inflammation of the uterine endometrium*
- This is known as **chronic endometritis**, often caused by infection and leading to intermenstrual bleeding, pelvic pain, and infertility.
- While pelvic pain is a symptom, the other characteristic symptoms and the presence of a tender adnexal mass make endometriosis a more fitting diagnosis.
Question 236: One day after doctors helped a 28-year-old primigravid woman deliver a 4700 g (10 lb 6 oz) boy, he has bluish discoloration of his lips and fingernails. Oxygen saturation on room air is 81%. Examination shows central cyanosis. A continuous machine-like murmur is heard over the left upper sternal border. A single S2 heart sound is present. Supplemental oxygen does not improve the cyanosis. Echocardiography shows the pulmonary artery arising from the posterior left ventricle and the aorta arising from the right ventricle with active blood flow between the right and left ventricles. Further evaluation of the mother is most likely to show which of the following?
A. Prenatal lithium intake
B. Elevated fasting blood glucose (Correct Answer)
C. Prenatal alcohol use
D. Positive rapid plasma reagin test
E. Prenatal phenytoin intake
Explanation: ***Elevated fasting blood glucose***
- The infant's symptoms (cyanosis, continuous machine-like murmur, and transposition of the great arteries with a large ventricular septal defect) are characteristic of a **large for gestational age (LGA) infant** born to a mother with **poorly controlled diabetes**. Maternal diabetes is a significant risk factor for congenital heart defects, including **transposition of the great arteries (TGA)**, and often leads to macrosomia.
- The description of the **pulmonary artery arising from the posterior left ventricle** and the **aorta arising from the right ventricle** confirms **TGA**. The "active blood flow between the right and left ventricles" indicates a **ventricular septal defect (VSD)**, which allows some mixing of blood and survival in TGA.
*Prenatal lithium intake*
- **Lithium exposure** during pregnancy is associated with Ebstein anomaly, a congenital heart defect affecting the tricuspid valve, not TGA.
- The clinical presentation of **Ebstein anomaly** would include right-sided heart failure and tricuspid regurgitation, differing from this case.
*Prenatal alcohol use*
- **Fetal alcohol spectrum disorders** can cause various congenital anomalies, including ventricular septal defects, but TGA is not characteristically associated with alcohol exposure.
- The overall cluster of findings, including the **macrosomic infant** (10 lb 6 oz), points more strongly towards maternal diabetes.
*Positive rapid plasma reagin test*
- A **positive rapid plasma reagin (RPR) test** indicates syphilis, which can cause congenital syphilis in the newborn, leading to conditions like non-immune hydrops fetalis, hepatosplenomegaly, and bone abnormalities.
- **Congenital syphilis** does not typically manifest with isolated congenital heart defects like TGA, nor does it cause macrosomia.
*Prenatal phenytoin intake*
- **Phenytoin exposure** during pregnancy can lead to **fetal hydantoin syndrome**, characterized by specific facial features, intellectual disability, and digit abnormalities.
- While central nervous system and cardiac defects can occur, **TGA is not a classic feature** of fetal hydantoin syndrome, and the infant's macrosomia is also not associated with phenytoin.
Question 237: A 64-year-old nulliparous woman comes to the physician because of fatigue and an increase in abdominal girth despite a 5-kg (11.0-lb) weight loss over the past 6 months. Her last Pap smear 2 years ago showed atypical squamous cells of undetermined significance; subsequent HPV testing was negative at that time. Menarche was at the age of 10 years and her last menstrual period was 6 years ago. Abdominal examination shows shifting dullness. There is tenderness to palpation of the left lower quadrant but no guarding or rebound. Bimanual palpation shows a small uterus and a left adnexal mass. Further evaluation of this patient is most likely to show which of the following findings?
A. Elevated serum beta-hCG level
B. Elevated serum CA-125 level (Correct Answer)
C. Proliferation of endometrial glands
D. Cervical dysplasia on cervical smear
E. Chocolate cyst of the left ovary
Explanation: ***Elevated serum CA-125 level***
- This patient's symptoms (fatigue, increased abdominal girth despite weight loss, shifting dullness, and a left adnexal mass in a postmenopausal nulliparous woman) are highly suspicious for **ovarian cancer**, for which **CA-125** is a key tumor marker.
- **Nulliparity**, early menarche, and late menopause (suggested by last menstrual period 6 years ago) are all risk factors for ovarian cancer, aligning with the suspicion for this diagnosis.
*Elevated serum beta-hCG level*
- An elevated **beta-hCG** is typically associated with **pregnancy** or **gestational trophoblastic disease**, neither of which fits this 64-year-old postmenopausal woman presenting with ovarian mass and ascites.
- While some ovarian germ cell tumors can elevate beta-hCG, the clinical picture is more suggestive of an epithelial ovarian malignancy.
*Proliferation of endometrial glands*
- **Endometrial gland proliferation** (hyperplasia or carcinoma) would typically cause **postmenopausal bleeding**, which is not mentioned in this patient's presentation.
- The adnexal mass and ascites are not primary features of endometrial pathology.
*Cervical dysplasia on cervical smear*
- The patient had a Pap smear 2 years ago showing **atypical squamous cells of undetermined significance (ASCUS)** with a **negative HPV test**, which significantly reduces the likelihood of high-grade cervical dysplasia or cervical cancer developing rapidly.
- Her current symptoms are more indicative of an **adnexal primary** rather than cervical pathology.
*Chocolate cyst of the left ovary*
- A **chocolate cyst** (endometrioma) is a type of **endometriosis**, which typically affects women of reproductive age and causes symptoms like dysmenorrhea, dyspareunia, and chronic pelvic pain.
- It is highly unlikely in a **64-year-old postmenopausal woman** like this patient, as endometriosis is estrogen-dependent and usually regresses after menopause.
Question 238: A 17-year-old girl presents to the gynecologist's office due to lack of menarche. She has been sexually active with 1 male lifetime partner and always uses a condom. Her mother believes that breast development started at 11 years old. On exam, she is a well-appearing, non-hirsute teenager with Tanner V breast and pubic hair development. Her pelvic exam reveals normal external genitalia, a shortened vagina, and the cervix is unable to be visualized. Initial laboratory testing for hormone levels and karyotype is normal, and imaging confirms what you suspect on exam. What is the most likely cause of her lack of menstruation?
A. Androgen insensitivity
B. Premature ovarian failure
C. Müllerian agenesis (Correct Answer)
D. 5-alpha reductase deficiency
E. Turner syndrome
Explanation: ***Müllerian agenesis***
- The patient presents with **primary amenorrhea**, normal secondary sexual characteristics (Tanner V breast and pubic hair), normal hormone levels, and a **shortened vagina** with an absent cervix, consistent with the diagnosis.
- This condition is characterized by the **failure of Müllerian duct development**, leading to an absent or hypoplastic uterus and vagina, while ovarian function and chromosomal makeup are normal.
*Androgen insensitivity*
- This would present with **primary amenorrhea**, but the patient would typically have a **46 XY karyotype** and lack pubic and axillary hair due to androgen receptor insensitivity, despite normal breast development.
- While breast development occurs, pubic hair development (Tanner V) would not be expected in **complete androgen insensitivity syndrome** since testosterone cannot stimulate hair follicles.
*Premature ovarian failure*
- This condition involves the **cessation of ovarian function** before the age of 40, leading to elevated FSH and LH levels due to lack of ovarian feedback, and often a lack of secondary sexual characteristics, which is not seen here.
- While it causes **primary amenorrhea**, it would not result in a shortened vagina or Müllerian anomalies; the uterus and vagina would typically be present.
*5-alpha reductase deficiency*
- Individuals with this condition are **genetically male (XY)** and are unable to convert testosterone to dihydrotestosterone (DHT), leading to varying degrees of masculinization at puberty, which is not consistent with a phenotypically female patient with normal external genitalia.
- This condition typically results in **ambiguous genitalia at birth** and virilization at puberty (clitoromegaly, partial fusion of labia), not a female phenotype with a shortened vagina.
*Turner syndrome*
- This is a chromosomal disorder (typically **45, XO**) characterized by **gonadal dysgenesis**, leading to short stature, webbed neck, cardiac defects, and most importantly, **absent or delayed puberty** and primary amenorrhea due to streak gonads.
- The patient would have **poor or absent breast development** due to ovarian failure, and elevated gonadotropins, which contradicts the normal breast development and hormone levels in this case.
Question 239: A 2250-g (5.0-lb) male newborn and a 2900-g (6.4-lb) male newborn are delivered at 36 weeks' gestation to a 24-year-old, gravida 1, para 1 woman. The mother had no prenatal care. Examination of the smaller newborn shows low-set ears, retrognathia, and right-sided clubfoot. The hematocrit is 41% for the smaller newborn and 69% for the larger newborn. This pregnancy was most likely which of the following?
A. Monochorionic-monoamniotic monozygotic
B. Conjoined twins
C. Dichorionic-diamniotic monozygotic
D. Monochorionic-diamniotic monozygotic (Correct Answer)
E. Dichorionic-monoamniotic monozygotic
Explanation: ***Monochorionic-diamniotic monozygotic***
- This is the most likely scenario given the significant **weight discordance**, **malformations** in one twin (low-set ears, retrognathia, clubfoot), and divergent hematocrit values suggesting **twin-twin transfusion syndrome (TTTS)**.
- **Monochorionic** indicates a shared placenta, allowing for vascular anastomoses that cause TTTS; **diamniotic** means separate amniotic sacs, which is typical for division between days 4-8 post-fertilization.
*Monochorionic-monoamniotic monozygotic*
- This type of twinning occurs with division after day 8-13 post-fertilization and would result in **both twins sharing the same amniotic sac**, increasing the risk of cord entanglement.
- While it's monochorionic and thus prone to TTTS, the presence of two distinct newborns without signs of cord entanglement makes diamniotic more likely.
*Conjoined twins*
- **Conjoined twins** result from incomplete separation of a monozygotic embryo after day 13, leading to physically connected infants.
- The description of two distinct newborns, despite the size and health differences, rules out physical fusion.
*Dichorionic-diamniotic monozygotic*
- While dichorionic-diamniotic twins can be monozygotic (splitting within the first 3 days post-fertilization), they typically have **separate placentas** or at least separate chorions.
- This arrangement significantly **reduces the risk of TTTS**, which is strongly suggested by the differing hematocrits and growth discordance.
*Dichorionic-monoamniotic monozygotic*
- **Dichorionic** means two separate chorions, implying separate placentas or at least separate chorionic membranes, making the significant vascular connection for TTTS unlikely.
- **Monoamniotic** (sharing one amniotic sac) with two chorions is a rare and highly unusual combination for monozygotic twins; it usually implies a very early split before chorion differentiation but without separate amnions.
Question 240: A 16-year-old girl presents with primary amenorrhea. On exam, you note that she is short and has a shield chest. You order abdominal imaging, which suggests the presence of streak gonads.
Of the choices listed below, which of the following karyotypes is possible in this patient?
I: 45,XO
II: 45,XO/46,XX mosaicism
III: 46,X,del(Xp) or other structural X abnormalities
A. I and III
B. I, II, and III (Correct Answer)
C. II and III
D. I and II
E. I only
Explanation: ***I, II, and III***
- The patient's presentation with **primary amenorrhea**, **short stature**, a **shield chest**, and **streak gonads** is classic for **Turner syndrome**.
- All three listed karyotypes (I: **45,XO**, II: **45,XO/46,XX mosaicism**, and III: **46,X,del(Xp)** or other structural X abnormalities) are recognized variants that cause Turner syndrome.
*I and III*
- This option incorrectly excludes 45,XO/46,XX mosaicism, which is a common and clinically significant **karyotype in Turner syndrome**.
- Mosaicism can lead to a milder phenotype but still presents with the characteristic features described.
*II and III*
- This option incorrectly excludes **45,XO**, which is the most classic and common karyotype found in individuals with Turner syndrome.
- The absence of a second X chromosome is the hallmark genetic defect.
*I and II*
- This option incorrectly excludes **structural X abnormalities** (e.g., deletion of the short arm of the X chromosome, **46,X,del(Xp)**), which are known causes of Turner syndrome.
- These structural changes lead to a similar clinical picture due to the loss of critical genes on the X chromosome.
*I only*
- While **45,XO** is the most common karyotype in Turner syndrome, confining the possibility to only this option is too restrictive.
- Both mosaicism and structural X abnormalities also result in the clinical features of Turner syndrome.
