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Flashcards in Parturition Deck (16)
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1
Q

What changes happen to the uterus in the pregnancy?

A

Increase in size: 4-70 grams to 1200 grams (not including the fetus)
Myometrial proliferation in early pregnancy
Myometrail hypertrophy in later half of pregnancy
Gap junctions between myometrium
Major increase in blood supply: From 2% of CO to 17% (Greater than the brain)

2
Q

What type of contractions are uterine contractions?
What is their mechanism?

A

Spontaneous contraction: No need for hormonal or nervous input

AP results in intracellular calcium increase
Calcium-calmodulin binding
Myosin light chain kinase activation allowing cross-bridging

3
Q

What transition needs to occur for myometrial cells to properly occur?

A

Transition to a labor phenotype
Shift from progesterone dominance to estrogen dominance

4
Q

Which hormones affect uterine contractility and how?

A

Progesterone

Inhibition intracellular calcium entry, SR release
Membrane hyperpolarization via K channels
Inhibits gene expression for pro-contraction
Levels are constant before and during labor

Estrogen

Increases gap junctions to promote synchrony
Increases oxytocin receptor and prostaglandin receptor expression in myometrium

5
Q

What pathways are involved in utterine contractions?

A

Uterine stretch and estrogen upregulate contraction-associated proteins (CAP)
Initiate excitation: GPCRs via PLC pathway
Increase frequency and amplitude of contractions

6
Q

What are the CAPs?

A

Gap junction connexin-43
Oxytocin receptor
Corticotropin-releasing hormone receptor
COX-2

7
Q

What are the triggers for labor?

A

Fetal adrenal gland plays an important role: fetal signal
Fetal HPA axis is immature
Maturity of HPA thought to induce contractions

Increased maternal estrogens
Increased PGs
Increase in CAP

8
Q

What is the definition of labor?

A

Regular contractions leading to cervical dilation over time

9
Q

What is pre-term labor defind as?
What are the causes?

A

Pre-term: 20-37 weeks gestation

Uterine distension: CAP, CRH, Estrogen, Oxytocin all increase
Infection: Toxins stimulate cytokines stimulating PGs
Preterm premature rupture of membranes: Apoptosis of cellular component of fetal membrane, MMPs play a role
Maternal-fetal stress: Premature rise in cortisol and estrogens can induce labor phenotype and stimulate fetal adrenal c19 hormones

10
Q

What is the public health correlation with pre-term births?

A

Leading cause of infant mortality and long term neurological disabilities

Preterm delivery rates lowest in Europe (6.2%), highest in Africa (11.9%)
12.1% in US
African-American concentration influences this and infant mortality most

11
Q

What are the risk factors of pre-term labor?

A

Preterm delivery rates lowest in Europe (6.2%), highest in Africa (11.9%)
12.1% in US
African-American concentration influences this and infant mortality most

12
Q

What pharmacological agents are involved in pre-term labor?

A

Magnesium, Beta-2 Agonist, Calcium Channel Blockers, Prostaglandin synthesis inhibitors: All act by blocking calcium influx
Progesterone therapy to prevent in patients with a history of preterm delivery and for patients with a shortened cervical length by ultrasound

13
Q

What is the definition of post-partum hemorrhage?
When does it occur and why?

A

Leading cause of maternal mortality
Definition: Symptomatic of hypovalemia
>500 mL after vaginal delivery
>1000 mL after cesarean delivery

Occurs during 4th stage of labor: Constant myometrial contraction necessary to limit blood loss
Uterine atony – Lack of contraction

14
Q

What are classic risk factors for atony?

A

Precipitous or prolonged labor
Polyhydraminous
Large fetal weight
Multifetal gestation
Retained placenta
Grand multiparity
Intrauterine infection
Uterine relaxation agents
Treated with uterine massage

15
Q

What are the pharmacologic treatments for post-partum hemorrhage?

A

Oxytocin, PGs, ergot alkaloid

16
Q

What is Sheehan’s syndrome?
How do the symptoms develop?

A

Pituitary infarction or necrosis due to hypovolemia

Symptoms due to secondary effects to many end organs
Symptoms may not develop immediately