Obstetrics 6: Preterm Labor Management Portal
Predisposing factors for preterm labor include previous preterm labor, uterine structural defects, over-distention of the uterus, infections, premature rupture of membranes, malposition, low socioeconomic status, substance abuse, emotional stress, and/or occupational stress. Other predisposing maternal factors include abdominal surgery, diabetes, hypertension, placental abruption, trauma, peritonitis, pancreatitis, and cholecystitis.
Patient Assessment
History
Determine whether labor is preterm. If it is, determine whether there
is a contraindication for tocolysis, such as maternal or fetal
compromise. Obtain the following information to formulate an action
plan:
- Labor
- Number, strength, duration, and frequency of contractions
- Symptom assessment: back pain, pelvic pressure, change in discharge, spontaneous rupture of membranes, fetal movement
- Associated conditions such as vaginal bleeding or leakage of amniotic fluid
- Dates
- Review LMP for accuracy.
- Review prenatal records for size and dates comparison.
- Determine whether an early pregnancy ultrasound has been done.
- OB History
- Determine risk factors for problems such as previous preterm labor, diabetes, growth retardation, hypertension, malposition, premature rupture of membranes, uterine structural defects, or low socioeconomic status.
- Other Medical Problems
- Includes maternal fever, dysuria, history of trauma or recent infections, history of abdominal surgery, pancreatitis, cholecystitis, peritonitis, and placental abruption
- Social History
- Risks include substance abuse, emotional stress, or occupational stress
- Determine the availability of support outside of the hospital.
Physical
- Check the patient's vital signs including temperature.
- Palpate the abdomen and uterus to elicit tenderness and to determine fetal size and presentation.
- Palpate the uterus for several minutes to determine quality and frequency of contractions.
- Perform a sterile speculum exam to assess for amniotic fluid leakage. (Use no lubricant until leakage has been determined.) Consider fetal fibronectin, and Group B Streptococcus culture.
- If membranes are intact, perform a careful digital exam to check cervical dilatation, effacement, and station.
- Monitor FHTs for at least 30 minutes to observe frequency and duration of contractions. Determine whether FHTs are reassuring.
- Obtain a urinalysis. If you suspect placental abruption, obtain coagulation studies and a hemoglobin. If you suspect chorioamnionitis, obtain a WBC count with differential. If amniotic fluid is available, obtain a toxicology screen.
- If Cesarean section is being contemplated, perform blood type and screen.
- At the time of cervical exam, obtain cervical culture for chlamydia, Group B Streptococcus, and gonorrhea. Check for bacterial vaginosis with a wet prep.
- If delivery does not seem imminent, perform ultrasound exam. (Vol III—OB2 Ultrasound Use)
- In a pregnancy of 33 to 35 weeks gestation, consider amniocentesis if the results may be obtained quickly and may change treatment.
Treatment
- Hydrate the patient with lactated Ringer’s solution, 500 to 1000 cc IV over 1 hour (if no contraindications) followed by 125 cc/hour.
- Treat any underlying conditions.
- If the patient has cystitis, UTI, or suspected Group B Streptococcus, initiate antibiotics.
- Prior to the transfer, tocolytic use is controversial but
is probably useful if cervical changes can be documented.
- If using a tocolytic, terbutaline 0.25 mg SQ every 1 to 4 hours can be given (or)
- Magnesium sulfate may also be used. Give a loading dose of 4 g as a bolus and follow with an infusion of 1 to 4 g/hour. Therapeutic levels for labor inhibition are 5.5 to 7.5 mg/dL.
- Give steroids if there are no contraindications, if the
fetus is 24 to 34 weeks gestational age, and if delivery is not
imminent.
- Betamethasone 6 to 12 mg IM every 12 hours for 2 to 4 doses over 24 to 48 hours or
- Dexamethasone 4 to 6 mg IM every 8 to 12 hours for 48 hours
Stabilization and Transport
Patient transfer
depends on:
- Fetal condition
- Imminence of delivery
- Availability of resources at the presenting hospital
- Availability of a safe means of transport to the referral center
If transfer is being considered, consult with a perinatologist.
- Perform the procedures listed under Diagnostic Studies and Treatment above to be sure the transfer is appropriate.
- Call the accepting facility to arrange transfer with a receiving physician.
- Consult with a high-risk obstetric consultant before starting tocolytics.
- Send with the patient a copy of all prenatal records, ultrasound tests, and laboratory results.
- Have someone experienced in delivery accompany the patient during the ambulance transfer.
- Arrange a plan of action prior to transfer and be aware of alternate hospitals en route in case delivery is imminent.
- Have additional IV fluids available to keep the IV patent.