Intro to OB Deck 2 Flashcards
Amniotic fluid - function
Distend the alveoli
Aquatic environment for fetal growth/movement
Protect (“cushion”) the umbilical cord
Amniotic fluid - production
Fetal kidneys are functioning from very early
AF is a “filtrate”, but it’s essentially salt + water
Removal of “poisons” is accomplished by the placenta and the MOTHER’s kidneys!
“NO, your baby is not swimming in its own urine”
Amniotic fluid - circulation
Fetal kidneys Into amniotic cavity via urethra Fetal “breathing” – in and out of fluid - Alveoli absorb a little - Helps alveoli develop Fetal swallowing – majority is here - reabsorbed by fetal stomach/intestine
Oligohydramnios – partial DDx
FH < expected – Leopold’s – fetal limbs palp Absent kidneys = “Potter’s Syndrome” Urethral obstruction Fetal “compromise” - ↓ utero-placental exchange - → ↓ fetal circulation (brain-sparing) - → ↓ fetal renal output IUGR syndromes
Oligohydramnios - risks
It’s a warning sign
Utero-placenta insufficiency
Cord compromise before and during labor
Hydramnios – partial DDx
Too much fluid – old term = “Polyhydramnios”
FH > expected, soft and mushy Leopold’s
Diabetes (usually not GDM)
History of hydramnios is repeating itself
Fetal anomalies – e.g. T-E fistual
Hydramnios - risks
Again – a warning sign
Sudden SROM before or during labor causing malpresentation or cord prolapse
Overdistended uterus → post-partum hemorrhage
genetic counseling
Tread lightly, but thoroughly
OB provider MUST ascertain “genetic risk”
But, at the same time, be SENSITIVE to patient’s values and wishes
(From the patient’s point of view: is “termination” ever an option?)
Patient has the right to refuse
Document your discussion !!!!!!!!!!
how in-depth do you go with genetic counseling?
Some patients don’t want any testing
Some want “every test in the book”- REFER these!!
Some have risk factors – REFER liberally
Trisomies
21 = Down’s Syndrome 18 = Edward’s Syndrome 13 = Patau’s Syndrome
“Non-disjunction” during meiosis
Rarely “familial” – chromosome translocations
Down’s risk correlates with maternal age:
1/270 @ 35
1/700 @ 23
Trisomy detection methods
Old way – offer amniocentesis to all over 35
Newer old way – offer tri- or “quad”- screen at ~ 16 weeks to everyone
Older new way = nuchal translucency + serum for PAPP-A and QHCG
NEW new way = cfDNA = cell-free DNA backed up with CVS (chorionic villus sampling) or amniocentesis
Neural tube defects
Spina bifida, etc.
AFP = alpha-feto protein = the fetal “albumin”
With “open” defect, AFP “leaks into amniotic fluid and hence into maternal serum
↑ MsAFP @ 16 weeks = indication for further workup – MsAFP isn’t definitive
Cystic fibrosis “CF”
Autosomal recessive
“Carrier” testing ~~ 1/25 for non-Hispanic white population
Amniocentesis if both mom/dad = carriers
Inborn errors of metabolism: Tay Sachs
hexosaminidase A absent
Autosomal recessive
Carrier state can be detected – screening programs ongoing
CVS or amniocentesis if both mom/dad carriers
High incidence of carriers in Ashkenazi Jewish pop - ~ 1/27 US Jewish pop
Where to deliver
First World – in appropriate facility
Other – “risking helps guide”
“Home birth”?? – more later…………..
DEM’s vs true CNM’s
The “experience” becomes all-important
What about the baby??
