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Flashcards in Labor and delivery Deck (34)
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1
Q

What vitamin (?) plays a role in controlling uterine muscle contraction

A

Calcium!
Ca flows into cytoplasm w/ transporters through channels
Ca-ATPase and Na/Ca exchangers maintain IC calcium homeostasis

2
Q

Uterine contractions depend on

A

formation of contractile protein actomysin and hydrolysis of ATP to produce motion

3
Q

What has an inhibitory effect on uterine contraction

A

ATP sensitive potassium channel stimulation AKA open K channels
(hyperpolarization of myometrial cells)

4
Q

Why do we have uterine contractions in labor

A

Promote cervical ripening (soft, thin cervix)
Control post-partum hemorrhage (MCC of perinatal maternal death)
Terminate pregnancy

5
Q

What drugs promote uterine contractions

A

Oxytocin: induce labor (contractions), promote cervical ripening
PGE2: promote cervical ripening and contractions
Carboprost: control postpartum hemorrhage
Mifepristone: terminate pregnancy
Methylergonovine: control postpartum hemorrhage

6
Q

How does oxytocin work

A

opens non-specific cation channels= open L type Ca channels= release of Ca from sarcoplasmic reticulum and decrease Ca efflux

7
Q

How do you dose oxytocin

A

Start low and gradually increase to desired effect

8
Q

Excessive uterine contractions can lead to

A

Uterine rupture

Fetal distress

9
Q

How do you use the PGE2 (dinoprostone) gel and how does it work (prepidil)

A

Place in cervical canal= cervical ripening
promotes uterine contractions
*Place in cervix when you plan on inducing labor w/ oxytocin in 1-2 days

10
Q

How do you place PGE2 (dinoprostone) vaginal insert (cervidil)

A

insert into posterior fornix of vagina

remove just before delivery

11
Q

Vaginal suppository of PGE2 can be used to

A

Terminate pregnancy 2/2 missed abortion, IU fetal death, and benign hydatiform mole); it is basically a stronger version (20mg) of Cervidil (10mg) and Prostadil (1/2 mg)
Can be used from week 12-20 of gestation

12
Q

ADE for all PGE2 include

A

nausea
vomiting
+/- fever
HTN and hypotension have been reported

13
Q

How does Carboprost work

A

Methylated analogue of PGF2a given IM; causes strong uterine contractions that is good for postpartum hemorrhage
Can induce uterine emptying at 13-20 weeks gestation, but NOT for elective abortions with a viable infant

14
Q

ADE of carboprost include

A
Bronchospasm (DO NOT use in asthma!) 
Hypertension 
Diarrhea 
Vomiting 
"Choking"
15
Q

How does Mifepristone work

A

Progesterone antagonist used to terminate pregnancy through 49 day of gestation
-Also used off label for cushing’s

16
Q

Why can Oxytocin be given postpartum

A

To enhance uterine contraction
given as a single IV infusion over several minutes
Must give after delivery of placenta

17
Q

How does Methylergonovine work

A

Causes uterine contractions and vasoconstriction

given IM postpartum (IV use discouraged 2/2 severe HTN and CVA)

18
Q

What are “tocolytic” agents

A

Agents that suppress uterine contractions, used MC to suppress labor that would result in a premie infant AKA women24-34 weeks at risk for delivering in the next 7 days
Prolong labor 48 hrs-1 week

19
Q

Tocolytic agents allow for use of other drugs to

A

accelerate fetal lung maturity!
Betamethasone IM q24 hrs, 2 doses
Dexamethasone IM q12 hrs, 4 doses

20
Q

What drugs suppress uterine contractions

A

Terbutaline (beta-2 agonist)
Nifedipine (inhibit calcium entry)
NSAIDs
MgSO4 (magnesium sulfate)

21
Q

What is an antidote to excess calcium

A

Magnesium sulfate!

22
Q

How does Terbutaline prolong labor (off label)

A

Causes uterine smooth muscle relaxation (like beta2 agonists do!) in airways and peripheral vasculature
Oral, subQ, or IV

23
Q

ADE of Terbutaline include

A
Tachycardia 
Pulmonary edema 
hypokalemia 
metabolic acidosis 
hypotension
24
Q

Black box warning for Terbutaline is

A

Do not oral dose or prolong parenteral use beyond 48-72 hours; risk of maternal cardiotoxicity an death!

25
Q

How long can MgSO4 be used to prolong pregnancy

A

5-7 days MAX!
Longer use can lead to hypocalcemia and increased risk of osteopenia and bone fractures in newborns
FDA not changed MgSO4 to a category D drug 2/2 evidence of human fetal risk

26
Q

IV mag sulfate CAN be used for

A

neuroprotection!

When used during preterm labor, incidence of moderate to severe cerebral palsy was reduced 50%

27
Q

ADE of Magnesium sulfate include

A

High serum magnesium= weakness, paralysis, respiratory failure, hypotension

28
Q

Because Mg is renally eliminated…

A

Renalinsufficiency impairs Mg elimination and can lead to toxicity

29
Q

In severe Mg toxicity, use

A

Hemodialysis to lower Mg levels

-In moderate cases IV calcium shots can be used

30
Q

How does nifedipine work

A

CCB; relaxes uterine smooth muscle and vascular muscle

31
Q

ADE of nifedipine include

A

Constipation

32
Q

How do NSAIDs help in prolonging labor

A

inhibit PG release= no uterine contractions! also inhibit platelet aggregation
They are 2/3 line and should only be used as tocolytics

33
Q

ADE of NSAIDs include

A

decreased GFR in baby

Narrowing or closure of fetal ductus arteriosus

34
Q

Hydroxyprogesterone caproate is given IM weekly to

A

maintain pregnancy in women with a Hx of recurrent miscarriage at >20 weeks
Begin weekly injection at 16 weeks
(these women are not progesterone deficient, but you can give progesterone to enhance uterine relaxation)