Chapter 11: Preterm Labor Flashcards
What is Preterm Labor (PTL)?
cervical changes and regular uterine contractions occurring between 20 and 37 weeks of pregnancy
>many present with preterm contractions, but only those who demonstrate changes in the cervix are diagnosed with PTL
Short term neonatal morbidities associated with premature birth
- respiratory distress syndrome
- intraventricular hemorrhage
- periventricular leukomalacia
- necrotizing enterocolitis
- bronchopulmonary dysplasia
- sepsis
- patent ductus arteriosus
Long-term morbidities associated with premature birth
- cerebral palsy
- intellectual and developmental disabilities
- retinopathy of prematurity
Risk for short-term and long-term morbidities is related to?
the infants gestational age and birth weight
Risk Factors Associated with Preterm Labor and Birth
- hx of preterm birth, especially in second trimester
- preterm premature rupture of the membranes (PROM)
- uterine or cervical anomalies
- multiple gestation
- hypertensive disorders of pregnancy
- diabetes (especially inadequately controlled)
- low pre-pregnancy weight
- clotting disorders
- bacterial infections
- fetal anomalies
- uterine overdistension (e.g. multiple gestation, hydramnios)
- vaginal bleeding, especially in the second trimester or in more than one trimester
- late or no prenatal care
- alcohol or drug use
- smoking
- cervical injury (e.g. related to surgery or elective abortion)
- Diethylstilbestrol (DES) exposure
- trauma including intimate partner violence (IPV)
- non-Hispanic African American race
- maternal age extremes (less than 16 years or greater than 40 years)
- low socioeconomic or educational status
- stress
- long working hours with long periods of standing
- periodontal disease
Risk Screening for Preterm Birth
- Fetal Fibronectin Testing
- Assessment of Cervical Length and Funneling
Fetal Fibronectin (fFN)
Fetal fibronectin (fFN) is a glycoprotein produced by the fetal membranes; normally present in the cervicovaginal fluid until 16 to 20 weeks of gestation
- described as the “glue” that attaches the fetal membranes to the underlying uterine decidua
- when uterine contractions occur, the adherence is disrupted and fFN is released
- fFN is a marker for the disruption of the chorioamnion and underlying decidua caused by inflammation with or without infection
Fetal Fibronectin Testing
-a positive fFN test result between 24 and 34 weeks has been associated with subsequently diagnosed maternal and fetal infection
>this test is done when the membranes are not ruptured and the patient is not bleeding
>the patient should not have a pelvic exam, vaginal ultrasound, or vaginal intercourse within the 24 hours prior to the collection
Fetal Fibronectin Testing: how to test for the presence of fFN
a sterile cotton-tipped swab is placed in the posterior vaginal fornix or in the ectocervical region of the external cervical os for a minimum of 10 seconds
-the collection swab is then removed, placed in a manufacturer-supplied medium, and sent to the lab
-results reported in 24 to 48 hours
>if test is negative (no fFN detected), the likelihood of giving birth in the following week is less than 1%
Assessment of Cervical Length and Funneling
association of cervical shortening (less than 15 to 25 mm, depending on gestational age) with preterm birth, particularly if associated with a positive fFN test result
- cervical length (CL) measurements are performed, with TVU or FDA-approved CervilLenz CL measuring device
- the risk of preterm delivery increases as the CL in the second trimester declines
Interventions to possibly prevent Preterm Labor
- preconception control of chronic medial conditions (e.g. diabetes, seizures, asthma, hypertension)
- smoking cessation
- routine prenatal screening and treatment for asymptomatic bacteriuria
- the use of laminaria for woman undergoing second trimester pregnancy termination via dilation and evacuation
- progesterone supplementation; Micronized progesterone vaginal gel or suppositories may reduce preterm labor, especially in woman with a history of preterm birth and a short CL verified by vaginal ultrasound
Micronized Progesterone Vaginal Gel or Suppositories
may reduce preterm labor, especially in woman with a history of preterm birth and a short CL verified by vaginal ultrasound
>progesterone supplementation should be offered to all women with a singleton pregnancy and a prior spontaneous preterm birth because of spontaneous preterm labor or premature rupture of the membranes
Diagnosis of PTL is diagnosed with this criteria is met
- a gestation of 20 to 37 weeks
- documented persistent uterine contractions (4 every 20 minutes or 8 in 1 hour)
- documented cervical effacement of 80% or greater
- cervical dilation of more than 0.4 in (1 cm) or a documented change in dilation
Signs and Symptoms
can be subtle
- backache
- pelvic aching
- menstrual-like cramps
- increased vaginal discharge
- pelvic pressure
- urinary frequency
- intestinal cramping with or without diarrhea
What has been implicated as a contributing factor in PTL
Infection
-prostaglandin production by the amnion, chorion, and decidua is stimulated by cytokines (extracellular factors) that are released by activated macrophages
>Group B streptococci, chlamydia, and gonorrhea have been associated with PTL and preterm premature rupture of the membranes
>important for nurse to obtain a clean-catch, midstream, or catheterized urine specimen to identify and treat infection if the patient presents with signs of PRL or premature rupture of the membranes
The two major goals in management of PTL
- inhibit or reduce the strength and frequency of contractions, thus delaying time of delivery
- optimize the fetal status before preterm delivery
Use of Tocolytics
to inhibit uterine contractions
- effective for up to 48 hours
- only women whose fetuses would benefit from a 48 hour delay in delivery should receive tocolytic therapy
What to take note of for medications
- no medication has been identified to effectively stop preterm labor
- no one drug is approved in the US or has been proven superior as a tocolytic agent
- medication selection is individualized based on efficacy, risks, contraindications, and side effects
Contraindications to the Use of Tocolytics in Preterm Labor
- Preeclampsia with severe features or eclampsia
- maternal bleeding with hemodynamic instability
- maternal contraindications to tocolysis (agent specific)
- non-reassuring fetal status
- fetal demise or lethal anomality
- chorioamnionitis
- preterm premature rupture of the membranes
- in the absence of infection, tocolytics may be considered for purposes of maternal transport, steroid administration, or both
What is the most beneficial intervention for the improvement of neonatal outcomes among woman who give birth preterm?
antenatal corticosteroids
-a single course of corticosteroids is recommended for pregnant women between 24 and 34 weeks of gestation who are at risk for preterm delivery within 7 days
-a single course is also administered to women with premature rupture of the membranes before 32 weeks of gestation
>have lower severity, frequency, or both, respiratory distress syndrome, intracranial hemorrhage, necrotizing enterocolitis, and death
>courses are: Betamethasone (12 mg) IM 24 hours apart for 2 doses, or Dexamethasone (6 mg) IM every 12 hours for 4 doses
>Maternal Risks: infection, pulmonary edema, hyperglycemia, or diabetic ketoacidosis
Maternal Risks Associated with Steroid Administration
- infection
- pulmonary edema
- hyperglycemia
- diabetic ketoacidosis
Antenatal Corticosteroid Courses for Improvement of Neonatal Outcomes among women who give birth preterm
-betamethasone (12 mg) IM 24 hours apart for 2 doses
-dexamethasone (6 mg) IM every 12 hours for 4 doses
>single course is recommended for pregnant women between 24 and 34 weeks of gestation who are at risk for preterm delivery within 7 days
>single course administered to woman with premature rupture of the membranes before 32 weeks of gestation
What are the first line Tocolytics
-beta-adrenergic receptor agonists (terbutaline sulfate)
-nonsteroidal anti-inflammatory drugs (indomethacin)
-calcium channel blockers (nifedipine)
>for short-term prolongation (up to 48 hours) of pregnancy to allow an opportunity to begin the administration of antenatal corticosteroids to accelerate fetal lung maturity
>also delaying birth provides time for maternal transport to a facility equipped with a neonatal intensive care unit
Magnesium Sulfate
a central nervous system depressant has also been used to inhibit acute PTL
- has limited effect as a tocolytic agent
- associated with risk factors: pulmonary edema and cardiovascular problems
- may exert a neuroprotective benefit, protecting the brain of the very preterm infant by possibly reducing the risk of cerebral palsy
Nursing Care of the Patient Receiving Tocolytic Therapy
- explore the woman’s understanding of what is taking place
- include patient’s partner in all discussions about medications and their effects
- provide anticipatory guidance regarding what is likely to happen during medication administration
- position the woman on her side for better placental perfusion (left side)
- explain the side effects and contraindications of the medication(s)
- assess blood pressure, pulse, and respirations regularly according to hospital policies (q 15 min)
- notify healthcare provider if systolic BP reads > 140mm Hg or < 90 mmHg
- notify healthcare provider if diastolic BP is > 90 mmHg or < 50 mmHg
- assess for signs of pulmonary edema (chest pain and SOB)
- assess for presence of deep tendon reflexes (DTR’s)
- monitor intake and output; avoid volume overload
- provide continuous external fetal monitoring for FHR pattern and frequency, duration, and approximate intensity of uterine contractions
- palpate the maternal abdomen to assess strength of uterine contractions
- provide psychosocial support and opportunities for the patient to express anxiety
- administer tocolytic therapy as ordered to delay delivery long enough to administer therapy corticosteroids to accelerate fetal lung maturity; complete maternal transport to a level III center prior to delivery; maternal antibiotic therapy to prevent neonatal Group B streptococcus (GBS) infection
Clinical alert for tocolytic nifedipine
avoid combining nifedipine with certain other medications
-Nifedipine, a calcium channel blocker used to inhibit preterm labor, works primarily by blocking the flow of calcium ions through the cell membrane (thereby decreasing the activation of smooth muscle contractile proteins); if nifedipine is given with magnesium sulfate or erythromycin, sudden cardiac arrest can occur
You may be experiencing preterm labor if you experience what?
- uterine contractions, cramping, or low-back pain
- a feeling of pelvic fullness, pressure, or pain
- a change in the amount or character of vaginal discharge
- GI symptoms: nausea, vomiting, diarrhea
- a general sense of discomfort or unease
Steps for Checking Contractions
- sit up from a reclining position and immediately place your hands on your abdomen–this action will often induce a uterine contraction
- if you are unsure, try flexing your arm and feel the contraction of the biceps muscle to get an understanding of what a muscle contraction feels like
If you believe you are having symptoms of preterm labor, take the following actions:
- empty your bladder
- lie down on your side
- drink two to three glasses of a caffeine-free beverage
- feel for uterine contractions
- call your health-care provider or go to the hospital for further evaluation if your symptoms persist or if you experience 4 or more contractions in 1 hour
