Womens health exam 4 - L4

What is preterm labor?

Labor symptoms occurring after 20 weeks but before 37 weeks gestation with cervical change

What is preterm birth?

Birth occurring before 37 weeks gestation

What cervical finding must be demonstrated to diagnose preterm labor?

Cervical effacement and dilation

How many contractions per hour are generally needed to produce cervical change?

>4 contractions/hour

Most common cause of neonatal morbidity and mortality

Preterm birth

What percentage of preterm births are spontaneous?

About 80%

Causes of spontaneous preterm birth

Preterm labor, PPROM, cervical insufficiency, and placental abruption

What percentage of preterm births are medically indicated?

About 20%

When do most preterm births occur?

32-36 weeks gestation

Risk factors for preterm labor

Previous preterm birth, assisted reproduction, multifetal gestation, extremes of maternal age, short cervix, prior LEEP/D&C, uterine abnormalities, HTN, CKD, T1DM, infections, smoking, substance use, undernutrition, short interpregnancy interval, stress, fetal male sex, and FGR

Genital infections associated with preterm labor

Bacterial vaginosis, gonorrhea, and chlamydia

Prodromal symptoms of preterm labor

Menstrual-like cramps, mild/irregular contractions, low backache, pelvic/vaginal pressure, mucus plug passage, and spotting

Cervical changes seen in labor

Softening, effacement, and dilation

How does cervical ripening differ from true labor?

Cervical ripening occurs over days/weeks; true labor changes occur over minutes/hours

Main goal of preterm labor evaluation

Identify true preterm labor so interventions can improve neonatal outcomes

What should history assess in suspected preterm labor?

Labor symptoms, bleeding, rupture of membranes, medical/obstetric history, and risk factors

What is assessed on physical exam for preterm labor?

Fundal height, contractions, FHR, uterine firmness/tenderness, and fetal position

What type of speculum should be used in suspected preterm labor?

Wet non-lubricated speculum

Why should lubricant be avoided during preterm labor evaluation?

It can interfere with vaginal specimen testing

What cervical dilation supports preterm labor?

≥3 cm

What does transvaginal ultrasound assess in preterm labor?

Cervical length

What cervical length is considered short?

<30 mm

What does abdominal ultrasound assess?

Fetus, placenta, and amniotic fluid

When can a digital vaginal examination be performed?

After rupture of membranes and placenta previa have been excluded

Other tests used in suspected preterm labor

Rectovaginal GBS swab, urine culture, STI testing, and fetal fibronectin if indicated

What is fetal fibronectin (fFN)?

Protein at the decidual-chorionic interface that acts like glue between the amniotic sac and uterine lining

Why can fetal fibronectin appear in cervicovaginal secretions?

Infection, inflammation, or contractions disrupt the decidual-chorionic interface

What is fetal fibronectin used for?

Helps predict risk of preterm birth

Where is fetal fibronectin collected?

Posterior fornix with a cervicovaginal swab

Who should receive fetal fibronectin testing?

<34 weeks, contractions present, cervical length 20-30 mm, dilation <3 cm, and intact membranes

Diagnostic criteria for preterm labor

≥6 uterine contractions in 1 hour PLUS cervical dilation ≥3 cm OR cervical length

How is suspected preterm labor ≥34 weeks triaged?

Admit for observation

What happens if there is no labor progression after 4-6 hours?

Discharge if fetal well-being is confirmed and obstetric complications are excluded

How is suspected preterm labor

Admit for observation and assess cervical dilation, cervical length, and fFN as indicated

Management of preterm labor

Corticosteroids, tocolytics, GBS prophylaxis, and magnesium sulfate for neuroprotection if

Which corticosteroids are used for fetal lung maturation?

Betamethasone or dexamethasone

Why are antenatal corticosteroids given in preterm labor?

Accelerate fetal lung maturity

Purpose of tocolytics

Reduce contraction strength/frequency and delay birth for up to 48 hours so corticosteroids can take effect

How long are tocolytics generally continued?

Up to 48 hours

First-line tocolytic at 32 to <34 weeks

Nifedipine

Second-line tocolytic at 32 to <34 weeks

Terbutaline

First-line tocolytic at <32 weeks

Indomethacin

Second-line tocolytic at <32 weeks

Nifedipine

Third-line tocolytic at <32 weeks

Terbutaline

When is magnesium sulfate given for fetal neuroprotection?

<32 weeks gestation

What is the fetal benefit of magnesium sulfate?

Reduces risk of cerebral palsy and other motor disorders

What is PROM?

Rupture of the amniotic sac before labor begins

What is another term for PROM?

Prelabor rupture of membranes

What is PPROM?

PROM occurring before 37 weeks gestation

What is prolonged PROM?

≥24 hours between rupture of membranes and onset of labor

Major concern with PROM

Chorioamnionitis/infection

Functions of amniotic fluid

Protects fetus from trauma, cushions umbilical cord, and has antibacterial properties

Major sources of amniotic fluid

Fetal urine and fetal lung secretions

Most common identifiable risk factor for PPROM

Genital tract infection

Other risk factors for PPROM

Smoking and abdominal trauma

Major complications of PROM/PPROM

Chorioamnionitis, maternal sepsis, placental abruption, cord prolapse, fetal malpresentation, and fetal/neonatal death

Typical history with PROM/PPROM

Leaking or gush of clear/pale yellow vaginal fluid

What exam is used to diagnose PROM?

Sterile speculum examination

What examination should be avoided with suspected PROM?

Digital vaginal examination

Gold standard physical finding for PROM

Pooling of fluid in the vaginal canal

What maneuver may help demonstrate fluid leakage?

Valsalva or coughing

Ultrasound finding with PROM/PPROM

Oligohydramnios (less amniotic fluid)

What does the nitrazine test measure?

pH of vaginal fluid

pH of amniotic fluid

7.0-7.3

Normal vaginal pH

3.8-4.2

What is a positive fern test?

Dried amniotic fluid shows an arborization/ferning pattern under microscopy

Management of term PROM ≥37 weeks

Oxytocin induction ± misoprostol for cervical ripening; cesarean if vaginal delivery contraindicated

Management of PPROM 34 to <37 weeks

Induction with oxytocin ± misoprostol, cesarean if indicated, possible corticosteroid, and GBS prophylaxis if status unknown

Management of PPROM <34 weeks

Expectant inpatient management, corticosteroids, antibiotics, daily NST, ± tocolytics, and magnesium sulfate if <32 weeks

Antibiotic regimen for PPROM

Azithromycin 1 g PO once PLUS ampicillin 2 g IV q6h for 48 hours, followed by amoxicillin 875 mg PO q12h for 5 days

What is chorioamnionitis?

Infection and inflammation of intrauterine structures

How does chorioamnionitis usually develop?

Ascending migration of cervicovaginal organisms to the decidual-chorionic interface

What increases the risk of chorioamnionitis after membrane rupture?

Longer duration of ruptured membranes

Clinical findings of chorioamnionitis

Fever, maternal/fetal tachycardia, WBC >15,000, uterine tenderness, and purulent amniotic fluid

Complications of chorioamnionitis

Protraction/arrest disorders, sepsis, perinatal death, and postpartum infection

Presumptive diagnosis of chorioamnionitis

Fever plus at least one of fetal HR >160 for ≥10 min, maternal WBC >15,000, or purulent cervical fluid

Findings that can confirm chorioamnionitis

Positive amniotic fluid Gram stain/culture, glucose ≤14 mg/dL, amniotic WBC >30,000, or histologic placental/fetal membrane infection

Management of chorioamnionitis

Initiate delivery and begin intrapartum antibiotics

Should delivery be delayed to complete corticosteroids in chorioamnionitis?

No

Antibiotics for chorioamnionitis

Ampicillin 2 g IV q6h PLUS gentamicin 5 mg/kg IV once daily

What is post-term pregnancy?

Pregnancy continuing beyond the expected term; management becomes important after 41 weeks

How common is post-term pregnancy?

Approximately 1-3% of pregnancies

Common reasons for apparent post-term pregnancy

Unknown cause or inaccurate gestational dating

Risk factors for post-term pregnancy

Previous post-term pregnancy, nulliparity, obesity, male fetus, and older maternal age

Maternal complications of post-term pregnancy

Vaginal trauma, labor dysfunction, cesarean delivery, and postpartum hemorrhage

Fetal complications of post-term pregnancy

Macrosomia, shoulder dystocia, dysmaturity, oligohydramnios, abnormal FHR, meconium passage/aspiration, and increased perinatal mortality

What is meconium?

Sterile, thick, black-green, odorless material in the fetal intestine

Why may meconium be passed before delivery?

Fetal stress

What is meconium aspiration syndrome (MAS)?

Respiratory distress in an infant born through meconium-stained amniotic fluid

When is MAS more common?

Post-term births or SGA infants

Management after 41 weeks gestation

Induction of labor ± cervical ripening OR expectant management with surveillance

How is a post-term pregnancy monitored expectantly?

NST with amniotic fluid assessment or BPP twice weekly

By what gestational age should labor be induced if it has not occurred?

42 weeks + 6 days

What is the Rh factor?

Inherited antigen located on the surface of red blood cells

What does Rh-positive mean?

Rh antigen is present

What does Rh-negative mean?

Rh antigen is absent

Which Rh antigen most commonly causes antibody formation?

RhD

When is Rh incompatibility a concern in pregnancy?

RhD-negative mother carrying an RhD-positive fetus

How does Rh sensitization occur?

Fetal Rh-positive RBCs enter the circulation of an Rh-negative mother, causing maternal antibody production

When is fetomaternal bleeding most common?

During birth