1. Agents Used in Obstetrical Care
Chapter 37
Agents Used in Obstetrical Care

2. The Uterus
Pear shaped organ
Highly muscular
Rich blood supply
Smooth muscle – very strong
During pregnancy uterus size increases tenfold

3. The Uterus
Strong rhythmic contractions can cause mild to strong discomfort or pain during labor
Many drugs stimulate smooth muscle of the uterus
Oxytocic agents
Initiate or increase uterine contractions
Used to control postpartum hemorrhage or to induce post first trimester abortion

4. Agents Used in Obstetrical Care
This presentation focuses on the following drug agents:
Uterine stimulants
Uterine relaxants
RhoGAM

5. 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

6. Oxytocin Dependent on estrogen’s presence
During last trimester uterus becomes more sensitive to oxytocin
Also released during intercourse to aid transport of sperm

7. Oxytocin 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

8. Oxytocin
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

9. Nursing Considerations
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

10. Ergot Derivatives
Complex mixture
Derived from fungus
Stimulates uterine smooth muscle
Ergonovine and methylergonovine
Causes powerful uterine contractions

11. 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

12. Nursing Considerations
Monitor blood pressure
Monitor for development of headache
Monitor postpartum bleeding
Monitor for signs of anemia

13. Prostaglandins
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

14. 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

15. Prostaglandins Hemabate - administered IM
- used for second trimester abortion and postpartum
hemorrhage
Dinoprostone
- vaginal suppository or gel
- promotion of cervical ripening
Adverse effects include nausea, vomiting, and diarrhea

16. Premature Labor
Premature birth accounts for most neonatal deaths
Stopping preterm labor is desirable
Usually attempted when labor starts after 20 weeks gestation

17. Uterine Relaxants
Prevent premature labor
Terbutaline sulfate (Brethine)
Stimulates beta2 receptors
Relaxes the uterus

18. Uterine Relaxants
Magnesium sulfate
IV, must be titrated carefully
Deep tendon reflexes should be monitored
Calcium gluconate: antidote

19. Nursing Considerations
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

20. Nursing Considerations
Educate 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 hours at a time due to risk of cardiac problems

21. RHoGAM
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

22. RhoGAM
Must be given with 72 hours of delivery
Never administer to an infant
Patients may experience pain at injection site, mild fever, or mild headache
Anaphylaxis is rare
Store in refrigerator; never freeze