Patozone

Pregnancy Overview

 

Trophoblast attaches to the uterine wall approximately 7 days post fertilization.

Maternal & fetal endocrine glands control hormones

Elevated estrogen & progesterone suppress LH & FSH & stimulate flow of prolactin.

 

hCG

 

Detectable post implantation

Rapid rise 8-12 weeks

Levels double every 48 hours

10-15% drop maintained till delivery, remains for about 2 weeks postpartum

- inc levels of hCG assoc c inc risk of Down syndrome

- women >35 yo routinely offered invasive prenatal diagnostic testing (usually amniocentesis, which results in fetal loss in 1/200 procedures)

 

Detect pregnancy in Urine or Serum

6 - 10 days post conception

- can get false negative with dilute urine or a false positive with heterophile antibody interference

 

Ectopic pregnancy

Extrauterine pregnancy – implantation in fallopian tubes to curnu - 1% of pts c fertility enhancement

Serial measurements of hCG are required

hCG levels do not elevate as high or as fast as true pregnancies - can rupture at any level (even <100)

- can get serum progesterone level (<5 = ectopic)

 

Hydatiform mole

hCG levels will increase with no apparent pregnancy, but levels are persistently low

- higher in complete than partial moles

Following a D & C serial hCG levels are used to verify the removal of all molar tissue - though can remain at low "phantom" levels for long periods of time

 

Pregnancy-Associated Plasma Protein A (PAPP-A)

 

Decreased levels of PAPP-A before the 14th WGA assoc c inc risk of Down syndrome and trisomy 18 (although low levels are also seen in trisomy 13, and other chromosomal anomalies)

- inc levels of PAPP-A (~1.86 Multiple of the Mean (MoM) seen in twin gestation

- inc levels of hCG assoc c inc risk of Down syndrome

- fetal nuchal translucency should also be performed by US as a third maker for fetal anomalies (is increased in majority of cases of Down syndrome)

- PAPP-A is produced by the placental syncytiotrophoblasts and deciduas

- chemically, it is a glycoprotein secreted as an active protease

 

Estriol

 

Major estrogen in pregnancy

Found in the urine of pregnant women

Made by placenta

Requires the fetal adrenal gland to provide necessary precursors

Levels reflect the growth of the fetus

Stimulates growth of the uterus and mammary glands

Indicates fetal distress when levels drop sharply

 

Progesterone

 

Indicates viability of the placenta but not the fetus

Inhibits uterine contractions

Stimulates mammary gland development

 

Human Placental Lactogen

 

Stimulates estrogen & progesterone

Stimulates development of mammary glands

 

Fetal Distress and Monitoring Well-Being

 

Fetal distress assoc c:

 

Congenital issues

Excess bilirubin

Pre-term delivery

Respiratory distress syndrome (RDS)

 

Lab tests in determining well-being

 

Alpha-fetoprotein

Used as an indicator for spinabifida, Down’s syndrome, stillbirth, and other chromosome abnormalities.

 

Bilirubin – spectral curve analysis of amniotic fluid protected from light

Method 1 – Liley scale - plot absorbance at 450 (the delta OD) against estimated gestational age

Method 2 – spectral scan of amniotic fluid looking for a peak at 450 nm

- reflects degree of fetal hemolysis

Must protect specimen from light (usually drawn into a brown tube)

 

Fetal Fibronectin

Used as an indicator for pre-term delivery

Its presence in weeks 24 – 34 may indicate woman to be at risk for pre-term delivery

More valuable as a negative predictor rather than positive predictor - low levels mean no preterm labor

 

Surfactant production the basis for other tests

Surfactant consists of

Lecithin

Phosphotidylinosital

Phosphatidylglycerol

Protein

Little, if any sphingomyelin

 

Fetal Lung Maturity Tests

fetal lungs usually are mature after 37 weeks

 

L/S ratio

Longest used test for predicting FLM

- lecithin inc c maturity, sphingomyelin stays same

Sensitivity = 96%; Specificity = 68%

Requires 3-4 hours of lab time

Affected by blood and meconium

Technically difficult to perform

Precision at 2.0 (maturity) is fairly low

- Laboratory Procedure:

Chloroform/methanol extraction

Cold acetone precipitation

Thin layer chromatography

Staining/charring of lipids

Measurement of lipid spots

Predicative value = 50/448

11% develop RDS

 

Phosphatidylglycerol, qualitative

- first detected @ ~37WGA

Sensitivity = 95%; Specificity = 65%

Time varies from 10 minutes to 4 hours

Not affected by blood or meconium

TLC methodology

AmnioStat-FLM

- Amnio-Stat Procedure:

No extraction

0.25 mL amniotic fluid

Immunologic agglutination assay

CLS performs interpretation

Positive when PG > 0.5ug/mL

15 minutes

Negative PG is usually followed up with L/S ratio or TDx FLM

 

Fluorescence polarization

 

FLM TDx

AF is filtered to remove debris

Quantitatively measures surfactant/albumin ratio

Run to run precision is 5%

12% will develop RDS

 

Lamellar body counts - test of choice***

LBC are produced at about 28 weeks

Lamellar bodies represents the structural form of pulmonary surfactant

Attempts to estimate surfactant production in utero

Flow cytometry, light scattering principle

15 minutes to perform

Affected by blood, meconium, mucus

Easy

Precision = 10%

Sensitivity = 100%

Specificity = 59%

LB are counted in the platelet channel of automated cell counter

 

 

Female Reproductive Anatomy

 

Ovaries

Estradiol – thecal cells

Progesterone – granulosa cells

 

Fallopian Tubes

Fingerlike projections that guide the ova after expulsion from the ovary

Fertilization occurs here

 

Uterus

Implantation of the fertilized egg

Lining sloughs off if fertilization does not take place – known as menstruation, period, etc.

 

Hormone Regulation

 

Four layers involved

1) Hypothalamus

GnRH

Controlled by dopamine & norepi

 

2) Anterior pituitary

Release of FSH & LH

Conversion of testosterone to estradiol between the thecal cells and granulosa cells

 

3) Ovary

LH & FSH causes granulosa cells to produce progesterone from the corpus luteum

Inhibin & progesterone provides negative feedback

 

4) Uterus

Produces progesterone to support fertilized egg

 

Females at Puberty

 

Characterized by 3 major events:

Onset of adrenal androgen secretion

Androstenedione

Dihydroepiandrosterone (DHEA)

Dihydroepiandrosterone sulfate (DHEAS or DHEA SO4)

 

Decreased sensitivity of the hypothalamus to negative feedback by gonadal steroids leading to increased Gn-RH release

 

Increased ovarian estradiol secretion and onset of cycles

 

Estradiol

Most potent

Increases # of glandular cells

Contributes to breast development

Increases osteoblastic activity

Retains Ca & PO4

Enhances secondary sexual characteristics

Used to assess ovarian function

 

Progesterone

Increases glandular cell secretion

Produced by the placenta during pregnancy

Used to evaluate fertility & the detection of ovulation

 

Contraception

 

Inhibition of ovulation by suppressing luteinizing hormone (LH);

Thickening of cervical mucus, thus hampering the transport of sperm;

Possible inhibition of sperm capacitation;

Hampers implantation of the egg

 

Female Infertility Syndromes

 

Uterine abnormalities

Tumors

Partial/total destruction of uterus

Asherman’s Syndrome

Tubular abnormalities

Chronic infections

Ovarian abnormalities

Results in anovulation

 

Abnormal Ovarian Function

 

Primary ovarian hypofunction

- Genetic disorder – Turner’s Syndrome

45 chromosomes = 44 normal + 1X not 2

Primitive ovaries – unable to ovulate

Increase in LH & FSH

Treatment = HRT does not restore fertility

 

- Menopause

Median onset = 50

Decreased steroidal feedback at the hypothalamus or pituitary

GnRH, LH, FSH no longer coordinated

Treatment = HRT

http://www.nhlbi.nih.gov/whi/

 

Secondary ovarian hypofunction

Abnormality lies somewhere along the hypothalmic-pituitary axis

Hypothalmic

GnRH center in hypothalmus is altered

Pituitary hemorrage

Sheehan’s syndrome (post-partum)

Hyperprolactemia

Pituitary tumor secreting prolactin

Anorexia

Delayed hormonal synthesis

 

Hyperfunction of the Ovaries

Primary – estrogen producing tumors

Decreases in FSH & LH

Secondary – idiopathic

Increases in LH, FSH

Polycystic Ovarian Syndrome (PCOS)

Stein-Levanthal syndrome

Male secondary sexual characteristics

Increased testosterone & LH

Decreased to normal FSH

LH/FSH ratio > 1.5

 

Investigation of female infertility

History & Exam

GnRH test

Clomiphine citrate test

Progesterone withdrawal test

Normal menses vs amenorrhea or oligomenorrhea

The chart on the next slide shows the algorithm for investigating female infertility

 

Gonadotropin releasing hormone test

 

Draw baseline LH & FSH

Give patient _______________

Draw blood every 15 for 1 hour

Measure LH & FSH at each draw

Normal response: LH & FSH peaks at 30 to 45 minutes

No Peak: __________________

 

 

Clomiphine citrate testing

 

Draw baseline LH & FSH

Give patient _________for 5 days

Draw blood for next 10 days

Measure LH & FSH at each draw

Normal response: LH should double in concentration from baseline

No Doubling: __________________

 

Progesterone withdrawl testing

 

Indirect measure of endogenous estradiol

Used to assess the uterus’ ability to receive a fertilized egg

Give the patient progesterone for 5 days

When the hormone is stopped, uterine bleeding should occur

This indicates the uterus is capable of handling a fetus to term

 

Male anatomy

 

Leydig cells

Located between and among seminiferous tubules

Site of testosterone synthesis

 

Sertoli cells

Site of androgen-binding protein

Mediate the first mitotic division of the spermatocytes

Provide necessary environmental conditions for germ cell maturation

 

Pulsatile release of GnRh

AP releases LH & FSH

LH is major regulator of testosterone production

• Binds to receptors on Leydig cells
• Pulsatile release
• Short half-life

 

FSH binds to receptors on the Sertoli cells

More constant release

Longer half-life

 

Negative feedback provided by

LH, testosterone, Inhibin B

LH → hypothalamus & AP

Testosterone → FSH & LH

Inhibin B → FSH

 

Spermatogenesis

Vital role is played by

Pituitary gonadotropins

FSH acts on the Sertoli cells

LH increases testosterone synthesis in Leydig cells

 

Testosterone

Stimulates spermatogenesis

Contributes to secretion of semen & ejaculation

Matures the secondary sex characteristics

Feeds back to the hypothalamus to inhibit the release of LH & FSH

 

Products of metabolism

Androsterone

Dihydrotestosterone

Androstenediol

Etiocholanolone

 

 

Male infertility

 

Pretesticular

Due to lesions in the pituitary or hypothalamus

Decreases in LH & FSH lead to decrease in testosterone

 

Testicular

Congenital

Cryptorchidism

Klinefelter’s syndrome

Acquired

Both result in decreased testosterone & increases in LH & FSH

 

Post-testicular

Due to functional or mechanical impairment of sperm transport system

No hormone levels involved