Male Infertility - Sandlow Flashcards
Give the three general etiologic categories of male infertility. Describe some causes of each. Which is the most common?
Pre-testicular
- Usually endocrinopathies
- Often associated with pituitary tumors or significant hypogonadism
- Highly treatable
Testicular (most common)
- Intrinsin problems with the testicle or surrounding structures
- Includes varicocele, gonadotoxins, primary testicular problems
- Usually reversible (variable)
Post-testicular
- Obstruction, ejaculation disorders
- Outlook variable
What is ‘normal’ testicular size (in cubic centimeters)?
18-20 ml
Why should testicular varicocele be evaluated while the patient is standing?
Lying supine can decompress the varicocele, making the characteristic ‘bag of worms’ less palpable or (in a high-grade varicocele) less visuall apparent.
Describe the general workup for evaluation of an infertile male
- Full HPI and PE
- Multiple (at least two) semen analyses -> sperm counts can be variable so do at least two to avoid false results
- Hormone studies to examine HPG axis (total T, FSH, reserve LH, estradiol, prolactin if T low)
- Scrotal U/S if testicular abnormality identified
Describe the expected semen analysis numbers in a healthy patient in terms of:
- Volume
- Concentration
- Motility
- Total motile sperm
- Total sperm
- Presence of other cells
- > 1.5-2 mL per ejaculate
- > 20e6 per mL
- >50% motility
- >20 million motile sperm
- >40 million total sperm
- Absence of WBCs, RBCs, or bacteria
Probably not high yield but…
Describe the (apparently strict) morphology of a typical normal/motile sperm cell
Heads: 2-3um x 3-5um
Neck: <1um diameter, 1.5x head length
Tail: 45um
How long does it take semen analysis to correct following therapeutic intervention?
~90 days
70 days from stem cell to spermatozoa
~20 days (technically 18) to transity epididymis
For sperm counts >10 million/cc, is hormone testing useful for identification of infertility?
No. Hormone tests for infertility are typically low-yield for sperm counts that approach normal levels
In male infertility, what two hormones should be evaluated to assess the integrity of the HPG axis?
FSH and testosterone
What is the most common etiology of male infertility?
What is the second most common etiology?
Varicocele
Idiopathic
Describe the pathophysiology of varicocele-induced male infertility
Countercurrent heat exchange between the testicular arteries and venous plexus normally keep the temperature of the testes 2-4 degrees C below body temperature (optimal for spermatogenesis)
Varicocele slows and disrupts this heat exchange, warming the testicles and distrupting spermatogenesis
Correction of varicocele corrects the temperature problem, correcting spermatogenesis
CFTR mutation is most prevalent in what race?
Why do we care about CFTR mutation?
Common in caucasians (1 in 25)
We care because though cystic fibrosis mutation may be mostly clinically apparent, 1-2% of infertility patients have this as an underlying etiology and 80-90% of these patients will have at least one mutated CFTR gene (most have 2)
Does CFTR mutation disrupt spermatogenesis?
Then why does infertility result?
Why is it important to give genetic counseling to the patient as well as his (female) partner?
No. Sperm are normal.
Infertility is derived from involution of the genital ducts during embyogenesis (the sperm are there, but they can’t get out - this is why IVF works with these patients)
If his female partner also carries a CFTR mutation, the probability of having a child born with clinically apparent CF is greatly increased
If CFTR testing for male infertility is negative, what is the next most likely etiology?
What is the most useful next test for this?
Why?
Renal anomalies
Renal U/S -> check for absent kidney
The mesonephric duct gives rise to the ureteral bud, as well as the vas deferens and lower 2/3 if the epididymis (clinical hint: only the head of the epididymis will be palpable)
Defects in the mesonephric duct lead to (ipsilateral) renal agenesis and absent genital ducts (ipsilateral)
