Agents Used in Obstetrical Care

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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