Infertility Flashcards
Define fertility.
- A measure of the actual outcome of the reproductive process.
- Measurable as the number of children born to an individual couple.
Define fertility rate.
Define fecundability.
Define fecundity.
- Fertility rate is the average number of children born per woman in a population.
- Fecundability is the monthly chance of pregnancy (within a single menstrual cycle).
- Fecundity is a measure of the ability to conceive and achieve a live birth.
Define infertility.
What is the NICE definition for infertility?
- The inability to conceive after a period of unprotected intercourse.
or
- The inability to carry a pregnancy to term.
- NICE defines infertility as failing to get pregnant after two years of regular unprotected sex.
Define subfertility.
A state of reduced fertility.
When do people seek medical advice for infertility?
After one year of unprotected sex.
*NB according to the NICE definition one year without pregnancy would be subfertility rather than infertility.
What is the average fecundability of the UK population?
How does this change with progressing months (6 months, 1 year and 2 years)?
- The average fecundability is 20%.
- 70% of people conceive within 6 months.
- 85% of people conceive within a year.
- 95% of people conceive within two years.
List the relative contributions to infertility of:
1 - Problems originating in the male.
2 - Problems originating in the female.
3 - Problems originating in a combination of both the male and female.
4 - Unknown problems.
to infertility incidence.
1 - Male problems account for 35% of infertility incidence.
2 - Female problems account for 35% of infertility incidence.
3 - A combination of both male and female problems account for 15% of infertility incidence.
4 - Unknown causes account for 15% of infertility incidence.
What proportion of female infertility is accounted for by disorders of ovulation?
Disorders of ovulation account for 40% of female infertility.
List 4 factors that contribute to female infertility.
1 - Ovulatory disorders.
2 - Tubal damage.
3 - Endometriosis.
4 - Uterine abnormalities.
List 5 disorders of ovulation that contribute to female infertility.
How do these disorders cause infertility?
1 - Absent cycles (primary / secondary amenorrhoea or oligomenorrhoea).
2 - Idiopathic ovarian failure (gonadotropin secretion is normal but is insufficient to support a normal cycle due to reproductive organ insensitivity).
3 - PCOS (see previous lectures).
4 - Luteinised unruptured follicle syndrome (eggs are deficient so the follicle doesn’t rupture).
5 - Abbreviated luteal phase (due to decreases in progesterone causing poor luteinisation).
List 2 causes of tubal obstruction that contribute to infertility.
1 - Secondary to pelvic infection, e.g. STDs.
2 - Sepsis post-abortion of post-pregnancy.
How might infection impair oocyte and sperm transport in the female reproductive system?
Infection can cause loss of cilia on the intraluminal cells and scarring, causing oocytes and sperm to adhere to the walls of the tract.
What is endometriosis?
- Escalated endometrial tissue growth in ectopic sites.
- As the tissue is still under the influence of oestrogen and progesterone, it can bleed and cause inflammation.
- This can disrupt implantation and affect ovarian reserve.
List 4 maternal problems (problems occuring after conception during pregnancy) that contribute to infertility.
1 - Cervical incompetence (cervical tissue widens and thins prematurely before term, causing premature birth).
2 - Implantation defects (ectopic pregnancies).
3 - Autoimmune diseases, e.g. lupus.
4 - Immunological incompatibility between ABO or Rhesus blood groups.
How is a pregnancy tested for biochemically?
Pregnancy is tested for biochemically by testing fro the presence of hCG in the blood and urine 18-30 days after the initiation of the last period.
How is a pregnancy tested for clinically?
Pregnancy is tested for clinically by:
- By ultrasound at 5 weeks to establish the presence of a foetal sac.
- By ultrasound at 7 weeks to establish the presence of a foetal heart.
In which trimester do most pregnancies fail?
Most pregnancies fail in the the first trimester.
In IVF, what proportion of embryos go on to become blastocysts?
What is the cause of this?
- In IVF, 20-40% of embryos go on to become blastocysts.
- This is due to genetic abnormalities.
List the 2 most common causes of chromosomal abnormalities resulting in miscarriage.
What proportion of all chromosomal abnormalities are accounted for by these causes?
1 - Trisomy (30%).
2 - Triploidy (15%).
List 5 factors that contribute to male infertility.
1 - Production of spermatozoa.
2 - Transport of spermatozoa.
3 - Transmission of spermatozoa.
4 - Sperm function in the female tract.
5 - Fertilisation.
What is considered an abnormally low sperm count?
What is the most common cause of abnormally sperm count?
- <5 million spermatozoa per millilitre is considered an abnormally low sperm count.
- The most common cause of an abnormally low sperm count is endocrinopathy.
List 9 values that are measured when evaluating sperm function.
1 - Ejaculate volume.
2 - Ejaculate pH.
3 - Spermatozoa concentration.
4 - Spermatozoa total number.
5 - Motility.
6 - Vitality (% alive).
7 - White blood cell concentration.
8 - % of anti-sperm antibody-coated spermatozoa.
9 - Spermatozoa morphology.
Define normozoospermic.
Define oligozoospermic.
Define asthenozoospermic.
Define teratozoospermic.
Define azoospermic.
- Normozoospermia is >15 million spermatozoa / ml with >32% rapid forward progressive motility and >4% normal morphology.
- Oligozoospermia is <15 million spermatozoa / ml.
- Asthenozoospermia is <32% rapid forward progressive motility.
- Teratozoospermia is <4% spermatozoa with normal morphology.
- Azoospermia is the absence of sperm.
List 4 causes of failure of production of sperm.
1 - Congenital testicular deficiency, e.g. Klinefelter (47, XXY) or Y chromosome deletion.
2 - Cryptorchidism (maldescended testes).
3 - Acquired, e.g. torsion of the testes or orchitis due to mumps.
4 - Endocrinopathy.
List 2 causes of failure of transmission of sperm.
1 - Erectile dysfunction.
2 - Ejaculatory dysfunctions, e.g. retrograde ejaculation.
Describe the process of normal ejaculation.
1 - The sympathetic nervous nervous system causes contraction of the musculature of the prostate, seminal vesicles and vas deferens.
2 - Seminal fluid and sperm are propelled into the urethra.
3 - Contraction of the vesicular urethral sphincter closes the bladder neck to prevent urine entering into the urethra.
4 - Contraction of the urethral and pelvic floor musculature release the semen from the penis.
What causes retrograde ejaculation?
Incompetence of the urethral sphincter causes semen to enter the bladder rather than the urethra.
List 3 causes of retrograde ejaculation.
1 - Diabetes.
2 - Post-traumatic paraplegia.
3 - Post-bladder neck surgery.
List 2 indications of retrograde ejaculation.
1 - Presence of semen in the urine post-ejaculation.
2 - Low volume ejaculate.
List 2 causes of low ejaculate volume other than retrograde ejaculation.
1 - Lack of emission of sperm.
2 - Ejaculatory duct obstruction.
List 2 causes of total failure of transport of semen, causing an absent ejaculate.
1 - Occlusion of the epididymis / vas deferens due to infection.
2 - Congenital bilateral absence of vas deferens (CBAVD).
Which gene is involved in congenital bilateral absence of vas deferens (CBAVD)?
Why is this clinically important?
- The cystic fibrosis transmembrane conductance regulator (CFTR) gene.
- This means that cystic fibrosis is associated with congenital bilateral absence of vas deferens.
Why do most men with congenital bilateral absence of vas deferens (CBAVD) have no symptoms of cystic fibrosis?
Because most men with congenital bilateral absence of vas deferens have only one severely mutated allele, and cystic fibrosis is an autosomal recessive condition.
List 5 causes of problems of sperm during fertilisation.
1 - Centriole dysfunction.
2 - Problems with chromatin decondensation.
3 - Problems with protamine exchange.
4 - Problems with pronuclear fusion.
5 - Problems with activation of genes for placenta formation.
List 6 conditions that must be true for infertility to be classified as unexplained.
1 - There is a normal frequency and distribution of unprotected intercourse.
2 - There are no obstructions or malformations in the tracts.
3 - There is normal follicle growth, maturation and ovulation.
4 - There are no signs of ongoing inflammatory reactions.
5 - There is a normal concentration of motile spermatozoa.
6 - There are no anti-sperm antibodies.
