Agents Used in Obstetrical

Care

Chapter 37

The Uterus

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Pear shaped organHighly muscularRich blood supplySmooth muscle – very strong

During pregnancy uterus size increases tenfold

The UterusStrong rhythmic contractions can cause mild to strong discomfort or pain during labor

Many drugs stimulate smooth muscle of the uterus

Oxytocic agentsInitiate or increase uterine contractions

Used to control postpartum hemorrhage or to induce post first trimester abortion

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Agents Used in Obstetrical Care

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This presentation focuses on the following drug agents:Uterine stimulantsUterine relaxantsRhoGAM

Oxytocin

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Oxytocin is a hormone excreted by the posterior pituitary gland

Primarily stimulates smooth muscle of the uterus and mammary gland

Synthetic oxytocin (Pitocin)Increases frequency and force of contractions

Oxytocin

Dependent on estrogen’s presence

During last trimester uterus becomes more sensitive to oxytocin

Also released during intercourse to aid transport of sperm

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Oxytocin

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Muscle contraction in mammary glands results in milk letdown

Synthetic form is Pitocin - used IV when initiating or augmenting labor

Infusion should be maintained at the lowest level to permit labor

Oxytocin

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Also used for postpartum hemorrhage, uterine atony, or after caesarean delivery

Can be administered IV in IV fluids or as an IM injection

When Pitocin is used before the fetus is delivered, fetal heart rate and pattern must be carefully and constantly monitored.

Pitocin during labor can cause exhaustion of uterine muscles (atony), stress on the baby, edema in the mother and other severe complications

Nursing Considerations

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Nurse must frequently assess vital signs, contraction strength and frequency, and fetal status during administration of oxytocin

Use of a pump for delivery is required Able to precisely control dosage

Continuous fetal heart rate monitoring is required

Ergot Derivatives

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Complex mixtureDerived from fungusStimulates uterine smooth muscle

Ergonovine and methylergonovine

Causes powerful uterine contractions

Ergot Derivatives

Not for use in induction or augmentation of labor

Used for postpartum hemorrhage

Usually given orally or IM (IV only in emergencies)

Can cause elevation of blood pressure

Potent vasoconstrictive effect

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Nursing Considerations

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Monitor blood pressureMonitor for development of headache

Monitor postpartum bleeding

Monitor for signs of anemia

Prostaglandins

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Can stimulate uterine contractions at any stage of pregnancy

Used in terminating pregnancy between 12th and 20th week

Used to treat incomplete abortion and fetal death

Prostaglandins

Use of prostaglandins for induction or augmentation of labor has not been approved by the FDA

Scientific evidence confirmed usefulness

Are approved for second trimester abortions

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Prostaglandins

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Hemabate - administered IM - used for second trimester abortion and postpartum

hemorrhageDinoprostone - vaginal suppository or gel - promotion of cervical ripeningAdverse effects include nausea, vomiting, and diarrhea

Premature Labor

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Premature birth accounts for most neonatal deaths

Stopping preterm labor is desirable

Usually attempted when labor starts after 20 weeks gestation

Uterine Relaxants

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Prevent premature laborTerbutaline sulfate (Brethine)Stimulates beta2 receptorsRelaxes the uterus

Uterine Relaxants

Magnesium sulfateIV, must be titrated carefully

Deep tendon reflexes should be monitored

Calcium gluconate: antidote

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Nursing Considerations

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Assess for signs of advancing labor

Assess for rapid heart rate or palpitations

Bed rest and pelvic rest required

Report pulse rate greater than 120 before giving dose

Nursing ConsiderationsEducate patients terbutaline can cause anxiety and tremors

Assess for signs of anxiety and tremors

Consider obtaining order for antianxiety medication

Terbutaline may not be given for more than 48-72 hours at a time due to risk of cardiac problems

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RHoGAM

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Sterile concentrated solution of gamma globulin

Administered IM to nonsensitized Rh-negative mothers after delivery of an Rh-positive baby

Suppresses formation of antibodies

Protects against hemolytic disease

RhoGAM

Must be given with 72 hours of delivery

Never administer to an infantPatients may experience pain at injection site, mild fever, or mild headache

Anaphylaxis is rareStore in refrigerator; never freeze

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