Medical Tests, Technologies, and Interventions

Source: *The Birth Partner* (5th ed.) — Penny Simkin with Katie Rohs

The Key Questions Framework

For every intervention or test, ask:

1. What is the benefit? What problem does this solve?

2. What are the risks or disadvantages?

3. What are the alternatives?

4. What happens if we wait, decline, or do nothing?

5. How urgent is this?

These questions are not adversarial. They are how informed consent actually works. A good caregiver will welcome them.

Late-Pregnancy Tests

Group B Strep (GBS) Screening

Done at 35 to 37 weeks with a vaginal/rectal swab.

About 25% of pregnant people carry GBS, a common bacteria that poses no risk to the carrier but can cause serious illness in the newborn.

If positive: IV antibiotics during labor (penicillin or ampicillin), given every 4 hours from the start of active labor until birth. This reduces the risk of newborn GBS infection by over 99%. The IV does not restrict movement significantly — it can be capped with a heparin lock between doses.

Implications for the birth partner: If GBS is positive and the bag of waters releases, the clock starts on getting to the hospital to begin antibiotics. Timing matters.

Nonstress Test (NST)

Used to assess fetal well-being, usually done weekly in the third trimester for high-risk pregnancies or after 40 to 41 weeks.

How it works: The laboring person lies with EFM belts on the abdomen. The caregiver watches the baby's heart rate for 20 to 40 minutes, looking for accelerations in heart rate that coincide with movement. Two accelerations of 15 beats per minute for at least 15 seconds within 20 minutes = reactive = good.

A "nonreactive" result (no accelerations) may mean the baby was sleeping, or it may indicate distress. Further testing (ultrasound, biophysical profile) is typically ordered before any intervention.

Ultrasonography

Used in late pregnancy to check: fetal presentation (which way the baby is positioned), estimated size, amniotic fluid volume (AFI), and placental position.

Margin of error for size estimation at term: plus or minus 1 pound or more. Weight estimates are often inaccurate and should not be used as a sole reason for induction.

Amniotic fluid level is affected by hydration: drinking 2 to 3 liters of water in the 24 hours before an ultrasound can improve a borderline AFI reading.

What Is Observed During Labor

Before any intervention, these are the baseline observations the care team makes continuously:

**Laboring person:**

• Behavior and responses (how they are coping)
• Contraction frequency, intensity, duration
• Uterine tone between contractions (should be soft)
• Vital signs: pulse, BP, temperature, respirations
• Location of pain (front, back, whole abdomen)
• Vaginal discharge and bleeding

**Amniotic fluid:**

• Color: clear or slightly pink = normal; brown or green = meconium = requires attention
• Amount: adequate, low, or high
• Odor: neutral or slightly sweet = normal; foul = infection concern

**Fetus:**

• Heart rate and pattern
• Estimated position and descent

**Newborn:**

• Apgar score at 1, 5, and 10 minutes after birth (see quick-reference)
• Temperature, respiration, pulse, color

IV Fluids

An IV line is placed in most hospital labors. It may be used to deliver fluids continuously, or it may be capped (heparin lock or saline flush) and accessed only if needed.

**Purposes:** Hydration if oral intake is limited; medication delivery; pre-epidural fluid loading; keeping a vein open for emergencies.

**Disadvantages:** Fluid retention (can contribute to breast engorgement and difficulty latching after birth); limits mobility slightly; infiltration (fluid leaking under the skin, causing local swelling).

**What helps:** Request a heparin/saline lock instead of a continuous drip if IV fluids are not medically indicated. This keeps the vein accessible without an attached bag. Drink something after every 1 to 2 contractions if oral intake is permitted.

Electronic Fetal Monitoring (EFM)

Continuous electronic monitoring of the fetal heart rate and uterine contractions throughout labor.

**External EFM:** Two belts worn on the abdomen. One uses ultrasound to detect the fetal heart rate; the other (tocodynamometer) detects the frequency and timing of contractions but not their intensity.

**Internal EFM:** A fetal scalp electrode (small spiral attached to the baby's scalp through the cervix) and an intrauterine pressure catheter (IUPC, placed through the cervix into the uterus). More accurate than external. Requires ruptured membranes.

**Portable/telemetry:** Wireless EFM that allows full freedom of movement, including the bath. Not available at all facilities — ask.

**Waterproof handheld Doppler:** A small device used for intermittent auscultation. Allows listening to the fetal heart rate without any belt or electrode.

**When EFM is medically indicated:** Pitocin augmentation or induction; high-risk conditions; significant concerns about fetal well-being; when the nurse cannot be continuously present.

**The evidence:** Studies show that continuous EFM (compared with intermittent auscultation) does not improve outcomes for low-risk labors and is associated with higher cesarean rates due to false-positive nonreassuring tracings. For low-risk births, intermittent auscultation (checking the heart rate every 15 minutes in active labor, every 5 minutes in pushing) is equally safe.

**Disadvantages of continuous EFM:** Restricts movement; tracings are complex and interpreted differently by different providers; cannot measure actual oxygen levels in the baby's blood; can lead to intervention based on pattern misinterpretation.

**What to ask:** "Is continuous monitoring medically indicated for our situation? Is intermittent auscultation an option? Do you have wireless telemetry or a waterproof Doppler available?"

Fetal Scalp Stimulation Test

A quick and useful test when the EFM strip looks concerning.

How it works: During a vaginal exam, the caregiver firmly strokes or scratches the baby's scalp. If the baby's heart rate accelerates by at least 15 beats per minute for at least 15 seconds, the baby is oxygenating well and the concerning EFM pattern is likely a false positive.

If there is no acceleration: further evaluation is warranted.

This test should be requested before agreeing to emergency cesarean for "fetal distress" based on EFM tracing alone, unless the situation is acutely urgent.

Artificial Rupture of Membranes (AROM / Amniotomy)

The caregiver uses a long, thin hook to break the amniotic sac.

**Stated purposes:** Speed active labor (studies show an average shortening of about 40 minutes IF the baby is well-positioned); induce labor; check amniotic fluid for meconium; place internal EFM.

**Disadvantages:**

• If the baby is not well-positioned, AROM may lock a poorly positioned baby in place and make correction harder
• Infection risk increases over time once membranes are ruptured
• The cushioning function of amniotic fluid is removed
• Cord compression risk increases
• Prolapsed cord risk if the baby's head is not well-engaged
• Frequently has no measurable effect on a cervix that is not ready

**The birth partner's role:** Ask the scalp stimulation test question before agreeing to AROM for "slow progress." Ask whether the baby's position has been assessed. Ask whether AROM is likely to help given where things are.

Amnioinfusion

Saline is infused through an intrauterine catheter to replace fluid or cushion the umbilical cord. Also used to dilute thick meconium.

**Requires:** Ruptured membranes; IUPC already placed.

**Disadvantages:** Infection risk; must remain in bed during infusion.

Induction and Augmentation

Induction means starting labor. Augmentation means speeding up labor already in progress.

Methods (in rough order of frequency of use)

**Stripping/sweeping membranes:** The caregiver uses a gloved finger to separate the amniotic sac from the lower uterine segment during a vaginal exam. Releases prostaglandins. Can cause cramping, spotting, and irregular contractions for hours. More reliably speeds cervical ripening than starting actual labor. Performed in the office.

**Prostaglandins:**

• **Cervidil:** A tampon-like insert left in the vagina for up to 12 hours, releasing prostaglandin E2. Can be removed if contractions become too strong. Requires hospital monitoring.
• **Prepidil (Cytotec/misoprostol):** A very effective prostaglandin. Can be given vaginally or orally. Warning: high doses have been associated with hyperstimulation (contractions that are too long, too strong, or too frequent, potentially stressing the baby). Should not be used in people with previous uterine surgery or cesarean scar.

**Pitocin (synthetic oxytocin):** The most commonly used augmentation/induction method. Given via IV at a carefully controlled dose, increased gradually. Requires continuous EFM because contractions may become more intense and longer than natural contractions. Can be turned off quickly if needed.

**AROM:** See above. Sometimes combined with Pitocin.

Medical Indications for Induction

• Pregnancy beyond 41 to 42 weeks (ACOG recommends offering induction at 41 weeks)
• Medical conditions: gestational hypertension, preeclampsia, gestational diabetes, cholestasis
• Evidence the baby is not thriving (IUGR, reduced fetal movement, low fluid)
• Prolonged rupture of membranes with GBS+ status
• Active herpes lesion approaching (to avoid emergency cesarean)

Elective Induction (Non-Medical)

Induction before 39 weeks for convenience significantly increases the risk of complications. After 39 weeks, the ARRIVE trial (2018) found elective induction at 39 weeks did not increase the cesarean rate for nulliparous (first-time) people. This shifted clinical practice substantially.

Disadvantages of elective induction at any gestation:

• Labor may be longer and harder than spontaneous labor
• Pitocin contractions can be more intense than natural contractions
• Higher rate of epidural use
• May not work if the cervix is not ready (failed induction can end in cesarean)
• Hospital capacity issues

Episiotomy

A surgical incision to enlarge the vaginal opening at the time of birth. Once routine, now rare.

**Appropriate uses:** Emergency shortening of the pushing phase when the baby is severely compromised; when the vaginal opening is extremely resistant to stretching; when forceps placement requires more space; premature baby (to reduce pressure on a fragile skull).

**Disadvantages:** Every episiotomy is a deliberate injury. It can extend into the rectum (third or fourth degree tear) in about 1 in 20 cases. Spontaneous tears, when they occur, are almost always smaller and heal more easily than episiotomy incisions.

**Prevention:** Warm compresses on the perineum during crowning; slow, controlled pushing; panting as the head emerges; prenatal perineal massage; good positioning.

**What to ask:** "What is your episiotomy rate?" and "Under what circumstances would you perform one?" A rate above 5 to 10% in a low-risk population is high by current standards.

Vacuum Extraction

A 3-inch suction cup is placed on the baby's head to assist delivery. The caregiver pulls during contractions while the laboring person pushes.

**Indicated:** Prolonged second stage due to fatigue or anesthesia; malposition; sudden fetal distress when the baby is low in the birth canal.

**Disadvantages:** A fluid-filled lump (caput) or bruise (cephalhematoma) on the baby's head, which resolves in days to weeks. Serious scalp injury is rare. If the cup pops off three times, the procedure is abandoned and cesarean considered.

**Alternatives:** Different pushing positions; directed versus spontaneous pushing; more time if both mother and baby are stable; forceps; cesarean.

Forceps

Two curved steel instruments placed on either side of the baby's head and locked (so they cannot compress). Used to guide the baby out.

**Indicated:** Delayed second stage; decreased contractions; large baby or poor positioning; baby showing distress low in the birth canal.

**Disadvantages:** Requires episiotomy and regional anesthesia. Bruising on the baby's head. Rare but possible nerve and injury. Vaginal and perineal injury to the birthing person.

**The birth partner's role with operative delivery:** Ask whether the baby's position has been assessed. Ask whether changing position or continuing to push is an option. Accept the caregiver's assessment in a true emergency. If there is time, ask about alternatives.