Male & Female Genitalia Flashcards
(22 cards)
What determines if a baby will be male or female at conception?
Male (XY chromosomes): The Y chromosome triggers testes development.
Female (XX chromosomes): Without a Y chromosome, ovaries develop by default.
What are the two early duct systems in all embryos?
Wolffian ducts (Mesonephric): Develop into male structures (vas deferens, epididymis) if testosterone is present.
Müllerian ducts (Paramesonephric): Develop into female structures (uterus, Fallopian tubes) if no anti-Müllerian hormone is present.
How do male external genitalia form?
Dihydrotestosterone (DHT) causes:
Genital tubercle → Penis.
Urethral folds fuse → Penile urethra.
Genital swellings → Scrotum.
How do female external genitalia form?
Estrogen causes:
Genital tubercle → Clitoris.
Urethral folds → Labia minora.
Genital swellings → Labia majora.
What is normal in a male newborn genital exam?
Urethral opening at the tip of the penis.
Both testes in the scrotum (with wrinkly skin called “rugae”).
No curvature of the penis (no chordee).
What is normal in a female newborn genital exam?
Labia majora and minora present.
Clitoris smaller than 1 cm (no enlargement).
Vaginal opening visible; slight bleeding or white discharge is normal (due to maternal hormones).
What is hypospadias?
The urethral opening is on the underside of the penis (not at the tip).
Action: Advise parents not to circumcise—the extra skin may be needed for surgery.
What is epispadias?
The urethral opening is on the topside of the penis.
Action: Urgent referral—may be part of a serious condition like bladder exstrophy.
What if a male newborn has undescended testes?
One testis not descended: Monitor; refer if not in place by 6 months.
Both testes not descended: Rule out intersex conditions or Congenital Adrenal Hyperplasia (CAH)—refer immediately.
What is Congenital Adrenal Hyperplasia (CAH) in females?
Virilized genitalia (enlarged clitoris, fused labia) in a baby with XX chromosomes.
Action: Urgent blood tests for electrolytes and hormones (risk of life-threatening salt imbalance).
What is ambiguous genitalia?
When the baby’s genitals do not clearly look male or female.
Action: Immediate referral for genetic testing, ultrasound, and hormone tests.
A newborn has a painless, swollen scrotum that glows when a light is placed against it. What is this?
Hydrocele (fluid around the testis). Usually resolves by age 1; refer if it persists.
A newborn is not passing stool. On exam, there is no anal opening. What is this?
Imperforate anus (a blocked or missing anus).
Action: Emergency surgery referral—may need a temporary stoma.
A newborn’s testis is dark, swollen, and firm. The baby is crying in pain. What is this?
Testicular torsion (twisted spermatic cord cutting off blood supply).
Action: Surgical emergency—refer immediately to save the testis.
Key Points to Remember: Always check
In males: Are both testes down? Is the urethra at the tip?
In females: Is the clitoris normal-sized? Is the vaginal opening visible?
Key Points to Remember: Do not ignore
Bilateral undescended testes (could be intersex/CAH).
Ambiguous genitalia (needs urgent tests).
Key points to remember: Never circumcise
Never circumcise a baby with hypospadias or epispadias—the skin may be needed for repair.
True or False? A small amount of vaginal bleeding in a newborn girl is always abnormal.
False—it’s normal due to maternal hormone withdrawal.
What hormone causes the Wolffian ducts to disappear in females?
Absence of testosterone (no Y chromosome → no testosterone → Wolffian ducts shrink).
A term baby boy has one testis not in the scrotum. What do you do?
Monitor and refer if it doesn’t descend by 6 months.
Study tips
Focus on hypospadias vs. epispadias, undescended testes, and CAH—these are common exam topics.
Practice describing normal vs. abnormal genitalia in your own words.
For exams, know when to refer urgently (e.g., torsion, ambiguous genitalia).
