β-hCG (mIU/mL)

• 
  

  Produced by cytotrophoblasts and syncytiotrophoblasts (primarily)

  
  
• 
  

  Ninety-two amino acid alpha subunit (identical to leutinizing hormone, follicle stimulating hormone, thyroid stimulating hormone (TSH)); 145 amino acid β-subunit (unique to hCG)

  
  
• 
  

  Serum/urine pregnancy tests are sensitive to levels of 1–20 mIU/mL (varies by test)

  
  
• 
  

  Within 24 hours of implantation (about 3 weeks after last menstrual period (LMP)), β-hCG is detectable in maternal serum. A sensitive pregnancy test can be (+) 1–2 days after implantation

  
  
• 
  

  Peak maternal levels reach about 100 000 mIU/mL (60–80 days after LMP); then decline; nadir about 16 weeks, and stay at this level for remainder of pregnancy (Figure 1-1)

  
  
• 
  

  After pregnancy (delivery or loss), it takes approximately 6–70 days for β-hCG to return to undetectable levels

  
  
• 
  

  Elevated levels also in molar pregnancy, renal failure with impaired hCG clearance, physiological pituitary hCG, and hCG-producing tumors (GI, ovary, bladder, lung)

Ultrasound

See Table 1-1, Guidelines for Transvaginal Ultrasonographic Diagnosis of Pregnancy Failure in a Woman with an Intrauterine Pregnancy of Uncertain Viability

Establishing Estimated Date of Delivery (EDD)

• 
  

  EDD is 280 days after the first day of the LMP (assumes regular, 28-day cycles, ovulation occurring at day 14, accurate recall)

  
  
• 
  

  Ultrasound in the first trimester (up to 13-6/7 weeks) is the most accurate method to establish/confirm gestational age (GA)—accuracy of ±5–7 days

  
  
• 
  

  If IVF pregnancy, age of the embryo, and date of transfer are used (day 5 transfer, EDD is 261 days from transfer date; day 3 transfer, EDD is 263 days from transfer date)

  
  
• 
  

  Average fetal heart rate (FHR) 90–110 bpm at 6 weeks. Poor prognosis if less than 90 bpm

  
  
• 
  

  See Table 1-2 for LMP vs ultrasound for establishing EDD

First Trimester Ultrasound (up to and including 13-6/7 weeks)

• 
  

  Most accurate method to establish/confirm EDD

  
  
• 
  

  Crown-Rump Length (CRL) (Figure 1-2)

  
  
  
  
  • 
    

    Use if GA is less than 14-0/7 weeks

    
    
  • 
    

    Accurate ±5–7 days

    
    
  • 
    

    Midsagittal plane

    
    
  • 
    

    Maximum length as a straight line from cranium to caudal rump

    
    
  • 
    

    Average of three discrete measures

    
    
  • 
    

    If CRL >84 mm (corresponding to about 14-0/7 weeks), accuracy of CRL decreases. Use other parameters

Second Trimester Ultrasound (14-0/7–27-6/7 weeks)

• 
  

  For dating, typically use BPD, HC, FL, and AC. See Figure 1-3

  
  
• 
  

  Accuracy

  
  
  
  
  • 
    

    Weeks 14-0/7–21-6/7: ±7–10 days

    
    
  • 
    

    Weeks 22-0/7–27-6/7: ±10–14 days

  
  
• 
  

  Biometry

Biparietal Diameter (BPD)

• 
  

  Transverse view, transthallamic view

  
  
• 
  

  Visualize thalami (*) and cavum septum pellucidum (arrows)

  
  
• 
  

  Cerebellar hemispheres should not be visible

  
  
• 
  

  Outer edge of skull to inner edge

Head Circumference (HC)

• 
  

  Same view as BPD; measure outer edges of calvarium

Femur Length (FL)

• 
  

  Measured from blunt end to blunt end, parallel to shaft

Abdominal Circumference (AC)

• 
  

  Landmarks: Fetal stomach (S), spine, umbilical vein joining portal vein (forms a “J”). Most variability among measures

Third Trimester Ultrasound (28-0/7+ weeks)

• 
  

  Least reliable method; accuracy ±21–30 days

  
  
• 
  

  DATING BY THIRD TRIMESTER ULTRASOUND ALONE IS PROBLEMATIC

  
  
• 
  

  Must use clinical picture to guide as a small fetus may have intrauterine growth restriction (IUGR)

  
  
• 
  

  Adjust EDD if this is first ultrasound and discrepancy from LMP is >21 days

  
  
• 
  

  May need repeat ultrasound to evaluate interval growth

Labor

Definitions

• 
  

  Three Stages of Labor

  
  
  
  
  • 
    

    First stage: Onset of contractions until complete cervical dilation

    
    
  • 
    

    Second stage: Complete cervical dilatation to expulsion of the fetus

    
    
  • 
    

    Third stage: Expulsion of the fetus to expulsion of the placenta

Historical Perspective (Friedman’s Work)

• 
  

  First stage of labor

  
  
  
  
  • 
    

    Latent phase: Begins with maternal perception of labor.

    
    
  • 
    

    “Prolonged” when >20 hours in nulliparas and >14 hours in multiparas

    
    
  • 
    

    Active phase: Point where rate of cervical dilation significantly increases

  
  
• 
  

  Active-phase labor abnormalities

  
  
  
  
  • 
    

    Protraction disorder: Slower progress than normal

    
    
    
    
    • 
      

      Cervical dilatation of <1.2 cm/h for nulliparous and <1.5 cm/h for multiparous

    
    
  • 
    

    Arrest disorders: Complete cessation of progress

    
    
    
    
    • 
      

      Absence of cervical change for ≥2 hours if adequate uterine contractions and cervical exam at least 4 cm

Contemporary Perspective (Table 1-3 and Figure 1-4)

• 
  

  More gradual increase in rate of cervical dilation as labor progresses

  
  
• 
  

  No clear transition from “latent” to “active”

  
  
• 
  

  Rates of cervical dilation less than 1 cm/h before 5–6 cm

  
  
• 
  

  From 4 to 6 cm, nulliparous and multiparous women dilate at essentially same rate (more slowly than historical definitions)

  
  
• 
  

  Beyond 6 cm, multiparous women have a slightly faster labor

  
  
• 
  

  Active phase may not start until at least 6 cm dilated

  
  
• 
  

  Median duration from 6 cm to complete dilation was 2.1 hours in nulliparas and 1.5 hours in multiparas

  
  
• 
  

  NOTE: these data excluded all women with cesarean delivery (CD) and compromised neonates. Only women who achieved vaginal birth with a normal infant outcome were included

  
  
• 
  

  Table 1-3 shows duration of labor from one cm of dilation to the next

Definitions—using contemporary data

• 
  

  Failed induction of labor: Failure to generate regular contractions and cervical change after at least 24 hours of oxytocin administration, with artificial membrane rupture if feasible

  
  
• 
  

  First-stage arrest: 6 cm or greater dilation with membrane rupture and no cervical change for

  
  
  
  
  • 
    

    ≥4 hours of adequate contractions (>200 Montevideo units (MVUs))

    
    
  • 
    

    ≥6 hours if contractions are inadequate

  
  
• 
  

  Second-stage arrest: No progress (descent or rotation) for

  
  
  
  
  • 
    

    ≥4 hours in nulliparous women with an epidural

    
    
  • 
    

    ≥3 hours in nulliparous women without an epidural

    
    
  • 
    

    ≥3 hours in multiparous women with an epidural

    
    
  • 
    

    ≥2 hours in multiparous women without an epidural

  
  
• 
  

  Bandl’s ring: Pathological retraction ring or constriction of uterus that develops with prolonged obstructed labors. Associated with thinning of lower uterine segment. May also occur between delivery of first and second twin

Important Points from ACOG/SMFM Consensus Statement*

• 
  

  Prolonged first stage has been associated with increased risk of chorioamnionitis, but this is not an indication for CD

  
  
• 
  

  Duration of second stage and association with

  
  
  
  
  • 
    

    Neonatal outcomes: Results are conflicting. Some studies show no relationship between adverse outcomes and longer pushing duration; however, others have shown adverse outcomes (5 min Apgar <7, neonatal intensive care unit (NICU) admission, increased neonatal morbidity)

    
    
  • 
    

    Maternal outcomes: More adverse outcomes with longer duration, such as higher rates of puerperal infection, third/fourth degree perineal lacerations, and postpartum hemorrhage. Also decreased probability of spontaneous vaginal delivery as time increases. After a ≥3 hour second stage, one of four nulliparas and one of three multiparas women deliver spontaneously

  
  
• 
  

  Performing low or outlet operative deliveries in fetuses not believed to be macrosomic may reduce risk of CD

Cesarean Delivery (CD)

• 
  

  Most common indications

  
  
  
  
  • 
    

    Labor arrest (34%)

    
    
  • 
    

    Abnormal or indeterminate (formerly nonreassuring) FHR (23%)

    
    
  • 
    

    Fetal malpresentation (17%)

    
    
  • 
    

    Multiple gestation (7%)

    
    
  • 
    

    Suspected fetal macrosomia (4%)

  
  
• 
  

  See Table 1-4 for ACOG/SMFM Recommendations for Safe Prevention of Primary Cesarean Delivery

Timing of Delivery

Terminology

Background/Recommendations

• 
  

  Medically Indicated Late Preterm and Early Term Delivery (Table 1-5)

  
  
  
  
  • 
    

    Early Term Delivery

    
    
    
    
    • 
      

      Non-medically indicated delivery before full term (39 weeks) is not appropriate

      
      
    • 
      

      Differences in morbidity and mortality between neonates delivered at 37 (and 38) weeks compared with 39 weeks are consistent across multiple studies

      
      
    • 
      

      Adverse neonatal outcomes in Early Term deliveries:

      
      
      
      
      
      

      | Download (.pdf) | Print
      

      
      

      
      
      
      
      
      

      Respiratory distress syndrome (RDS) Transient tachypnea of the newborn Ventilator use Pneumonia

      NICU admission Hypoglycemia 5-minute Apgar <7 Neonatal mortality

      
      
      
      
      
      
      
      
    • 
      

      Although greatest risks of Early Term delivery are respiratory, nonrespiratory morbidity is also increased. Documenting fetal lung maturity does NOT justify early nonindicated delivery

  
  
• 
  

  A reduction of nonindicated deliveries before 39 weeks should not be accompanied by an increase in expectant management of those with maternal or fetal indications for delivery before 39 weeks

  
  
• 
  

  Late Term and Post Term

  
  
  
  
  • 
    

    Risk factors for Post Term (about 5% of pregnancies): Nulliparity, prior post term pregnancy, male fetus, maternal obesity, possible genetic predisposition, fetal disorders (anencephaly, placental sulfatase deficiency)

    
    
  • 
    

    Post Term associated with increased perinatal morbidity and mortality

    
    
    
    
    • 
      

      Neonatal convulsions, meconium aspiration syndrome, 5-minute Apgars <4, NICU admission

      
      
    • 
      

      Increased risk of macrosomia (twofold), increasing risk of operative and CD, and shoulder dystocia

      
      
    • 
      

      More frequent oligohydramnios (increasing risk of FHR abnormalities, meconium, umbilical cord pH <7)

      
      
    • 
      

      Increased fetal mortality compared to 40 weeks

      
      
      
      
      • 
        

        41 weeks—1.5 fold; 42 weeks—1.8 fold; 43 weeks—2.9 fold

    
    
  • 
    

    Post Term associated with increased maternal risks:

    
    
    
    
    • 
      

      Severe perineal lacerations, infection, postpartum hemorrhage, CD

    
    
  • 
    

    Trial of labor after cesarean (TOLAC) failure rate increases with GA

    
    
    
    
    • 
      

      Before 40 weeks: 22.2% failure rate

      
      
    • 
      

      After 41 weeks: 35.4% failure rate

    
    
  • 
    

    Management

    
    
    
    
    • 
      

      Fetal testing: Start at 41-0/7 weeks. Insufficient data to define optimal type/frequency. Twice weekly modified biophysical profiles (BPPs) [Nonstress test (NST) + amniotic fluid index (AFI)] or BPPs are reasonable

      
      
    • 
      

      Membrane sweeping reduces risk of late term and post term

      
      
    • 
      

      Induce labor after 42-0/7 weeks

Induction of Labor (IOL)

• 
  

  Although often stated that IOL increases rate of CD, the relationship between IOL and CD is controversial. Data are insufficient!

  
  
• 
  

  When IOL is compared to expectant management, either NO difference in CD or a decreased risk of CD has been reported in women undergoing IOL

  
  
• 
  

  Predictors of successful vaginal delivery: Multiparity, favorable cervix

  
  
• 
  

  Cervical ripening methods should be used with an unfavorable cervix as they are associated with a lower rate of CD

  
  
• 
  

  Latent phase is longer in IOL

  
  
• 
  

  Elective IOL should not be performed before 39-0/7 weeks (increased neonatal morbidity and mortality)

  
  
• 
  

  No consensus on IOL versus expectant management at full term (39-0/7–40-6/7 weeks)

Cervical Ripening

• 
  

  No single definition to differentiate favorable from unfavorable

  
  
• 
  

  Bishop Scoring System has been used (Table 1-6). Originally developed to predict likelihood of multiparous women at term to enter spontaneous labor. Generally

  
  
  
  
  • 
    

    Favorable: Bishop’s score >8 has same likelihood of vaginal delivery with IOL as spontaneous labor

    
    
  • 
    

    Unfavorable: Bishop’s score ≤6

Methods of Cervical Ripening

PGE₁–Misoprostol (Cytotec^®)

• 
  

  Effective for ripening and induction

  
  
• 
  

  Most common complication is tachysystole (with or without FHR changes)

  
  
• 
  

  Optimal dose and dosing interval not known

  
  
• 
  

  Contraindications

  
  
  
  
  • 
    

    Previous uterine scar

  
  
• 
  

  Administration

  
  
  
  
  • 
    

    Misoprostol 25 μg is placed in the posterior fornix of the vagina

    
    
  • 
    

    Frequency of administration: Every 3–6 hours

    
    
  • 
    

    Higher dose (50 μg) may be appropriate in certain cases; however, there is a greater risk of tachysystole

    
    
  • 
    

    Oral dosing is possible (buccal, sublingual); however, limited data are available

    
    
  • 
    

    Oxytocin should not be administered <4 hours after last misoprostol dose

PGE₂ – dinoprostone (Cervidil^®, Prepidil^®)

• 
  

  Cervidil^®: Dinoprostone 10 mg, timed-release vaginal insert, leave in up to 12 hours. Can remove if tachysystole or FHR abnormalities. Oxytocin may be started 30 minutes after removal

  
  
• 
  

  Prepidil^®: Dinoprostone 0.5 mg in 2.5 mL gel for endocervical administration. Repeat dose in 6–12 hours. Maximum dose 1.5 mg in 24 hours. Oxytocin should not be started prior to 6–12 hours after final dose

  
  
• 
  

  Contraindications

  
  
  
  
  • 
    

    Previous uterine scar

    
    
  • 
    

    Caution if glaucoma, severe hepatic or renal dysfunction, or asthma

• 
  

  Directly dilate cervix

  
  
• 
  

  Cause release of prostaglandins

Balloon Catheters (Foley Bulb)

• 
  

  Contraindications:

  
  
  
  
  • 
    

    Placenta previa, vasa previa, low-lying placenta

  
  
• 
  

  Procedure

  
  
  
  
  • 
    

    Place using aseptic technique. Insert either under direct visualization (use ring forcep and pass through cervical os) or place similar to an intrauterine pressure catheter (IUPC)

    
    
  • 
    

    Instill 30–60 mL saline into balloon; apply traction (tape to inner thigh)

    
    
  • 
    

    If bleeding or resistance, discontinue

    
    
  • 
    

    No consensus on management of Foley bulb in setting of ruptured membranes

    
    
  • 
    

    Foley bulb plus oxytocin does not appear to shorten time to delivery when compared to Foley bulb alone

Osmotic Dilators

• 
  

  Laminaria Tents

  
  
  
  
  • 
    

    Absorb moisture and gradually expand

    
    
  • 
    

    Removed after 12–24 hours

    
    
  • 
    

    Designed for first and second trimester termination

    
    
  • 
    

    No large-scale trials for term cervical ripening

Membrane Sweeping

• 
  

  Increases likelihood of spontaneous labor within 48 hours. Insufficient data for recommendations if GBS (+)

Amniotomy

• 
  

  Insufficient evidence on amniotomy alone for IOL; however, with oxytocin, may be shorter interval to delivery

Oxytocin Induction/Augmentation (at term)

• 
  

  Gradual increase in uterine response to oxytocin from 20 to 30 weeks, then plateaus from 34 weeks until term. Sensitivity then increases with spontaneous labor

  
  
• 
  

  Uterus responds within 3–5 minutes; steady level in plasma by 40 minutes

  
  
• 
  

  Various protocols exist; institutions typically standardize their own protocols

  
  
  
  
  • 
    

    Low-dose oxytocin protocols typically involve increases of 1–2 mU/min every 15–40 minutes.

    
    
  • 
    

    High-dose oxytocin protocols may involve increases of 3–6 mU/min every 15–40 minutes

    
    
  • 
    

    At Johns Hopkins, our high-dose protocol is 4 mU/min increases every 15 minutes

    
    
  • 
    

    40 mU/min is usually maximum dose

  
  
• 
  

  Increase oxytocin per protocol until an adequate contraction pattern is achieved

  
  
• 
  

  Adequate labor in MVUs: 200

• 
  

  Dilation and evacuation (D&E) is associated with fewer complications than IOL

  
  
• 
  

  Rare complications of both D&E and IOL include hemorrhage, cervical laceration, retained products of conception, infection; uterine perforation in D&E; and uterine rupture in IOL

  
  
• 
  

  IOL may be preferable at times (fetal anomalies, genetic disorders)—intact fetus

  
  
• 
  

  Adding mifepristone, a progesterone receptor antagonist that primes the uterus and cervix, appears to shorten expulsion time

  
  
• 
  

  With IOL, consider premedicating for fever/nausea/vomiting/diarrhea. IV PCA or epidural for pain management

  
  
• 
  

  See Table 1-7 for IOL regimens for second trimester termination of pregnancy

Examples of High-Dose Oxytocin Protocols (may be used in women with prior uterine scar)

• 
  

  14-0/7–26-0/7 weeks: Oxytocin 200 units in 500 mL NS at 50 mL/h (20 units/h)

  
  
  
  
  • 
    

    Place laminaria prior to starting oxytocin

    
    
  • 
    

    High doses for prolonged periods of time can lead to water retention and hyponatremia

    
    
  • 
    

    Check electrolytes after 7–12 hours

  
  
• 
  

  26-1/7–28-0/7: Oxytocin 200 units in 500 mL NS at 25 mL/h (10 units/h)

After Fetus Delivers

• 
  

  If placenta has NOT delivered: Can start Oxytocin 40 units in 100 mL NS at 50 mL/h

  
  
• 
  

  If D&C, antibiotic prophylaxis with doxycycline (100 mg IV) or cefazolin (2 g IV)

• 
  

  Rates are declining

  
  
• 
  

  Account for approximately 3.6% of births in the United States (vacuum:forceps is 4:1)

  
  
• 
  

  Failure to result in delivery: Forceps 0.4%; vacuum 0.8%

  
  
• 
  

  Fetal (nonreassuring fetal status) and maternal (exhaustion, prolonged second stage, maternal comorbidities such as heart disease) indications

  
  
• 
  

  Do not switch from vacuum to forceps or vice-versa due to increased neonatal morbidity

Prior to performing, ensure

• 
  

  Fetal position and station

  
  
• 
  

  Adequate maternal anesthesia

  
  
• 
  

  Empty maternal bladder

  
  
• 
  

  Personnel for neonatal resuscitation are available if needed

Vacuum-Assisted Deliveries

• 
  

  Contraindicated if under 34 weeks gestation or estimated fetal weight is <2500 g

  
  
• 
  

  A maximum of three “pop-offs,” three sets of pulls, and/or a total vacuum application time of 15–30 minutes is commonly recommended. No data-based guidelines are available

  
  
• 
  

  Application (Figure 1-5)

  
  
  
  
  • 
    

    Apply at “flexion point”—center of cup approximately 3 cm in front of posterior fontanelle and 6 cm from anterior fontanelle

    
    
  • 
    

    Avoid placing over fontanelles

    
    
  • 
    

    Palpate around entire cup after placement to verify maternal tissue is not under cup

    
    
  • 
    

    Consider lowering suction level between contractions

    
    
  • 
    

    Do not attempt to rotate the fetal head or use rocking movements

    
    
  • 
    

    Maximum suction pressure should not exceed 600 mm Hg

  
  
• 
  

  Fetal risks (Figure 1-6)

  
  
  
  
  • 
    

    Retinal hemorrhages (20–40%)

    
    
  • 
    

    Superficial abrasions (10%)

    
    
  • 
    

    Cephalohematoma (delineated by suture lines, limited in size) (14–16%)

  
  
• 
  

  Clinically significant fetal risks

  
  
  
  
  • 
    

    Subgaleal hemorrhage (2.6–4.5%). Bleeding not contained by sutures

    
    
  • 
    

    Intracranial hemorrhage (<0.5%)

    
    
  • 
    

    Skull fracture (<0.5%)

Forceps-Assisted Deliveries

Application (Figure 1-7)

• 
  

  Sagittal suture should be perpendicular to the plane of the forcep shanks

  
  
• 
  

  Posterior fontanelle should be midway between blades and one finger’s breadth above plane of shanks

  
  
• 
  

  With fenestrated blades, a small but equal amount of fenestration should be felt on each blade

Risks

• 
  

  Facial nerve injury (<0.5%)

  
  
• 
  

  Cephalohematoma (2%)

  
  
• 
  

  Depressed skull fracture

  
  
• 
  

  Maternal: Third and fourth degree lacerations (13–44%)

Classification of Forceps Deliveries (Table 1-8)

• 
  

  Classical instruments

  
  
  
  
  • 
    

    Elliot type

    
    
    
    
    • 
      

      Overlapping shanks

      
      
    • 
      

      Short, rounder cephalic curve

      
      
    • 
      

      Best for round, unmolded heads, no caput

      
      
    • 
      

      Examples: Tucker–McLane, Elliot

    
    
  • 
    

    Simpson type

    
    
    
    
    • 
      

      Parallel, separated shanks

      
      
    • 
      

      Long, tapering cephalic curve

      
      
    • 
      

      Fit better on longer, molded heads

      
      
    • 
      

      Examples: DeLee, Irving

Perineal Laceration Definitions

Episiotomy

• 
  

  Per ACOG, “The best available data do not support liberal or routine use of episiotomy … there is a place for episiotomy for maternal or fetal indications, such as avoiding severe maternal lacerations or facilitating or expediting difficult deliveries”

  
  
• 
  

  Types

  
  
  
  
  • 
    

    Median: “Midline” (Figure 1-8)

    
    
    
    
    • 
      

      Place fingers between fetal head and perineum. Incise 2–3 cm aiming at 6:00

      
      
    • 
      

      Extends to the transverse perineal muscles

      
      
    • 
      

      Easier repair; better healing

      
      
    • 
      

      Greater risk of extension into a third or fourth degree

    
    
  • 
    

    Mediolateral: 45 degrees from midline

    
    
    
    
    • 
      

      Similar technique with scissors aimed at 5:00 or 7:00, toward ipsilateral ischial tuberosity

      
      
    • 
      

      Bulbospongiosus is main muscle that is incised

      
      
    • 
      

      More difficult to repair

      
      
    • 
      

      Increased blood loss

      
      
    • 
      

      Increased pain

Laceration Repair

• 
  

  Antibiotic prophylaxis should be considered with third and fourth degree repairs—single dose of a second-generation cephalosporin or clindamycin if allergic to penicillin

Third Degree Laceration Repair – See Figure 1-9

• 
  

  End-End Repair

  
  
  
  
  • 
    

    Grasp ends of the external anal sphincter muscle and capsule with Allis clamps

    
    
  • 
    

    Place interrupted sutures at the 3:00, 6:00, 9:00, and 12:00 positions through the capsule of the sphincter. Place the inferior and posterior sutures first

    
    
  • 
    

    Repair second degree in typical fashion

  
  
• 
  

  Overlapping Repair

  
  
  
  
  • 
    

    Alternative method

    
    
  • 
    

    Current data do not suggest this repair provides superior results compared to end-end

Fourth Degree Laceration Repair – See Figure 1-9

• 
  

  Identify apex

  
  
  
  
  • 
    
    
    
    • 
      

      For rectal mucosa, use 4-0 suture in running or locking fashion. Should not penetrate mucosal layer. Place reinforcing layer through rectal muscularis (3-0 suture) in running or interrupted fashion

      
      
    • 
      

      Repair third degree as above

Terminology

• 
  

  Trial of labor (TOL) or trial of labor after cesarean (TOLAC): A planned attempt to labor by a woman with a previous CD

  
  
• 
  

  VBAC: Vaginal birth after cesarean; successful trial of labor

  
  
• 
  

  Unsuccessful or failed TOL: CD after a TOL

  
  
• 
  

  Elective repeat CD: Planned CD in woman with one or more prior CDs

Success Rates

• 
  

  Evidence suggests that women with at least a 60–70% chance of VBAC have equal or less maternal morbidity when they undergo TOLAC than women undergoing repeat CD. If less than 60% chance of success, more chance of morbidity with TOLAC

  
  
• 
  

  Success rates for trials of labor are consistently high (overall: 60–80%)

  
  
• 
  

  VBAC Calculator: https://mfmunetwork.bsc.gwu.edu/PublicBSC/MFMU/VGBirthCalc/vagbirth.html

  
  
• 
  

  Factors Associated with Increased Success

  
  
  
  
  • 
    

    Prior vaginal birth

    
    
  • 
    

    Spontaneous labor

    
    
  • 
    

    Nonrecurring indication (ie, breech)

    
    
  • 
    

    Birth weight <4000 g

    
    
  • 
    

    Prior successful VBAC. Rate of VBAC increases with each prior VBAC.

    
    
    
    
    • 
      

      No prior SVD: 63% VBAC

      
      
    • 
      

      Prior SVD before CD: 83% VBAC

      
      
    • 
      

      Prior VBAC: 94% VBAC

  
  
• 
  

  Factors Associated with Decreased Success

  
  
  
  
  • 
    

    Recurrent indication for initial CD (ie, second stage arrest)

    
    
  • 
    

    Increased maternal age

    
    
  • 
    

    Nonwhite ethnicity

    
    
  • 
    

    GA >40 weeks

    
    
  • 
    

    Maternal obesity

    
    
  • 
    

    Preeclampsia

    
    
  • 
    

    Short interpregnancy interval

    
    
  • 
    

    Increased neonatal birth weight

    
    
  • 
    

    Labor augmentation/induction

Uterine Rupture

• 
  

  Uterine rupture: Complete separation of all uterine layers leading to possible fetal or maternal compromise

  
  
• 
  

  Uterine scar dehiscence: Often an occult scar separation with intact uterine serosa; does not lead to fetal or maternal compromise

  
  
• 
  

  Rate of symptomatic uterine rupture for women who undergo TOL: 0.7–0.8%. See Table 1-9 for Rates of Uterine Rupture according to prior uterine incision type

  
  
• 
  

  Low vertical uterine incision: LIMITED DATA. ACOG says likely same success rate as low transverse; NIH says “increased” risk of rupture

  
  
• 
  

  Unknown scar: Only a problem if high clinical suspicion of previous classical CD

  
  
• 
  

  Women with more than one prior CD

  
  
  
  
  • 
    

    Per ACOG: Limited data; however, it is reasonable to attempt TOLAC in patients with two previous CDs. One large study showed no increase in uterine rupture rates with multiple prior CDs (0.9% versus 0.7% with one CD); another found increase from 0.9% with one prior CD to 1.8% with two prior CDs

  
  
• 
  

  Labor augmentation/induction

  
  
  
  
  • 
    

    Oxytocin: Possible increase in risk of rupture (up to 1.5% versus 0.8% with spontaneous labor)

    
    
  • 
    

    Misoprostol: Increased risk of rupture

  
  
• 
  

  Single versus double layer uterine closure: conflicting data; studies suggest possible decreased uterine rupture in 2 layer closure versus 1 layer closure

  
  
• 
  

  Twins: Similar outcomes to singletons. No increased risk

Signs of Uterine Rupture

• 
  
  
  
  • 
    

    Nonreassuring FHR pattern with decelerations or bradycardia

    
    
  • 
    

    Loss of station

    
    
  • 
    

    Hypovolemia

    
    
  • 
    

    New onset intense uterine pain

    
    
  • 
    

    Vaginal bleeding

Miscellaneous

• 
  

  No data suggest monitoring with IUPC is superior to external monitoring to prevent uterine rupture

  
  
• 
  

  External cephalic version (ECV) is not contraindicated in women with prior CD if appropriate candidate for TOLAC and ECV

  
  
• 
  

  Effective regional anesthesia may be used and will not mask signs and symptoms of uterine rupture

  
  
• 
  

  TOLAC should be undertaken at facilities equipped to perform immediate emergency deliveries

• 
  

  Terminology

  
  
  
  
  • 
    

    Low-Lying Placenta

    
    
    
    
    • 
      

      Placental edge within 2 cm of internal os

      
      
    • 
      

      Follow-up ultrasound recommended at 32 weeks gestation

      
      
    • 
      

      Vaginal delivery more likely if placental edge is 10–20 mm from os

    
    
  • 
    

    Placenta Previa

    
    
    
    
    • 
      

      Placenta covers internal os

      
      
    • 
      

      Follow-up ultrasound recommended at 32 weeks gestation

      
      
    • 
      

      Incidence of placenta previa: 1:200 births

      
      
    • 
      

      Risk factors for placenta previa: Previous CD, maternal age, smoking, multiples, multiparity, previous uterine curettage

      
      
    • 
      

      Placenta covers os in about 5% of pregnancies midpregnancy; the majority resolve when the upper third of cervix develops into lower uterine segment; placenta “migrates” away

      
      
    • 
      

      Presentation: Painless vaginal bleeding (most commonly around 34 weeks)

  
  
• 
  

  On 32 week follow-up ultrasound: If still low-lying or previa, follow-up transvaginal ultrasound recommended at 36 weeks

• 
  

  Definitions: Abnormal attachment of the placenta to the uterine wall. See Figure 1-10

  
  
  
  
  • 
    

    Accreta: General term used to describe condition when placenta invades and is inseparable from uterine wall

    
    
  • 
    

    Increta: Invasion into myometrium

    
    
  • 
    

    Percreta: Invasion through myometrium and serosa, occasionally into adjacent organs such as the bladder

  
  
• 
  

  Occurs in approximately 3:1000 deliveries

  
  
• 
  

  Risk Factors

  
  
  
  
  • 
    

    Placenta previa, especially if prior CD (Table 1-10)

    
    
  • 
    

    Prior uterine surgery

    
    
  • 
    

    Increasing parity

    
    
  • 
    

    Maternal age >35

  
  
• 
  

  Diagnosis

  
  
  
  
  • 
    

    Ultrasound

    
    
    
    
    • 
      

      Sensitivity: 77%

      
      
    • 
      

      Specificity: 96%

      
      
    • 
      

      Positive predictive value: 65%

      
      
    • 
      

      Negative predictive value: 98%

    
    
  • 
    

    MRI

    
    
    
    
    • 
      

      Sensitivity and specificity are comparable with ultrasound

      
      
    • 
      

      May be useful to determine extent of invasion and involvement of abdominal/adnexal structures or when ultrasound is nondiagnostic

  
  
• 
  

  Prognosis

  
  
  
  
  • 
    

    Average blood loss at delivery is 3–5 L

    
    
  • 
    

    90% require blood transfusion

    
    
  • 
    

    40% require more than 10 units of packed red blood cells

    
    
  • 
    

    About two-thirds require cesarean hysterectomy

    
    
  • 
    

    Maternal mortality is as high as 7%

  
  
• 
  

  Management of suspected placenta accreta

  
  
  
  
  • 
    

    Timing of delivery must be individualized. PLANNED delivery is associated with fewer complications and less blood loss

    
    
  • 
    

    Multidisciplinary team, including pelvic surgeon (eg, gynecologic oncologist)

    
    
  • 
    

    Maternal and neonatal outcome is optimized in stable patients with planned delivery at 34 weeks without amniocentesis for FLM

    
    
  • 
    

    Avoid manual removal of placenta. Leave placenta in situ → hysterectomy

Early-Onset GBS

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  Infection in newborn within first week of life. (Late Onset GBS—infant older than 6 days)

  
  
• 
  

  Leading infectious cause of morbidity and mortality in infants in the United States

  
  
• 
  

  Mortality higher among preterm (about 20–30% if ≤33 weeks versus 2–3% in full term)

  
  
• 
  

  Risk factors for early-onset GBS disease in infants

  
  
  
  
  • 
    

    Maternal genital tract colonization (10–30% of pregnant women)

    
    
  • 
    

    GBS UTI any time during pregnancy (2–7% of women). Surrogate for heavy maternal colonization (even if vaginal-rectal swab is negative)

    
    
  • 
    

    GA less than 37-0/7 weeks

    
    
  • 
    

    Prolonged rupture of membranes (≥18 hours)

    
    
  • 
    

    Intra-amniotic infection (≥38.0 C)

    
    
  • 
    

    Young maternal age

    
    
  • 
    

    Black race

    
    
  • 
    

    Previous delivery of infant with invasive GBS disease

Testing for GBS

• 
  

  Collect at 35–37 weeks GA in all women unless diagnosed with GBS bacteriuria in this pregnancy or previous infant with invasive GBS disease

  
  
  
  
  • 
    

    Swab lower vagina (introitus), followed by the rectum (through anal sphincter)

  
  
• 
  

  If planned CD

  
  
  
  
  • 
    

    Patients should still undergo routine screening for GBS at 35–37 weeks. Onset of labor or rupture of membranes (ROM) may occur before the planned CD

    
    
  • 
    

    Administer antibiotics IF labor/ROM

  
  
• 
  

  Results good for 5 weeks

Neonatal Perspective

• 
  

  Appropriate antibiotics ≥4 hours before delivery highly effective. Shorter duration (≥2 hours) may provide some protection

  
  
• 
  

  No medically indicated obstetric procedure should be delayed to achieve 4 hours of prophylaxis prior to delivery

Antibiotics for GBS Prophylaxis (Table 1-11)

• 
  

  Indications for prophylaxis (Table 1-11)

  
  
• 
  

  Antibiotic recommendations (Figure 1-11)

  
  
  
  
  • 
    

    Penicillin is the agent of choice; ampicillin is an acceptable alternative

    
    
  • 
    

    Increasing resistance to erythromycin (25–32%) and clindamycin (13–20%)

    
    
    
    
    • 
      

      Erythromycin NO LONGER recommended

  
  
• 
  

  Algorithm for GBS Prophylaxis in Preterm Labor (Figure 1-12)

Definitions

Uterine Contractions

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  Number of contractions in a 10-minute window, averaged over 30 minutes

  
  
  
  
  • 
    

    Normal: ≤5 contractions in 10 minutes, averaged over a 30-minute window

    
    
  • 
    

    Tachysystole: >5 contractions in 10 minutes averaged over a 30-minute window

    
    
    
    
    • 
      

      Always note presence/absence of associated FHR decelerations

      
      
    • 
      

      Applies to both spontaneous and induced labor

    
    
  • 
    

    The terms hyperstimulation and hypercontractility are not defined and should be abandoned!

Fetal Heart Rate Patterns

Baseline: Mean FHR (rounded to 5 bpm) in 10-minute window, excluding accels, decels, and periods of marked variability (>25 bpm). Baseline must be for at least 2 (not necessarily contiguous) minutes in any 10-minute segment

• 
  

  Normal: 110–160 bpm

  
  
• 
  

  Tachycardia: >160 bpm for 10 minutes or longer

  
  
• 
  

  Bradycardia: <110 bpm for 10 minutes or longer

Variability: Fluctuations in baseline FHR that are irregular in amplitude and frequency

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  Absent: Amplitude from peak to trough undetectable

  
  
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  Minimal: Amplitude from peak to trough detectable but ≤5 bpm

  
  
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  Moderate: Amplitude from peak to trough 6–25 bpm

  
  
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  Marked: Amplitude from peak to trough >25

Accelerations: Abrupt increase (onset to peak <30 seconds) in the FHR

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  At ≥32 weeks, acceleration has peak of ≥15 bpm above baseline, with a duration of ≥15 seconds but <2 minutes from onset to return

  
  
• 
  

  Before 32 weeks, acceleration has peak of ≥10 bpm above baseline, with a duration of ≥10 seconds but <2 minutes from onset to return

  
  
• 
  

  Prolonged acceleration: ≥2 minutes and <10 minutes

  
  
• 
  

  If an acceleration lasts >10 minutes it is a baseline change

Decelerations: Decrease in FHR associated with contractions or other physiologic events. Periodic decelerations are abrupt (peak <30 seconds) or gradual (peak >30 seconds); recurrent if occur with ≥50% of contractions in any 20-minute window; intermittent if occur in less than 50% of contractions (see Figure 1-13)

Early Deceleration

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  Usually symmetrical, gradual decrease and return of FHR associated with a contraction

  
  
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  From the onset to the FHR nadir of ≥30 seconds

  
  
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  Nadir of deceleration occurs at the same time as peak of contraction

  
  
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  Decrease ≤15 bpm below FHR baseline

  
  
• 
  

  In most cases, onset, nadir, and recovery are coincident with the beginning, peak, and end of contraction

  
  
• 
  

  Due to head compression

Late Deceleration

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  Usually symmetrical, gradual decrease and return of FHR associated with a contraction

  
  
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  From the onset to FHR nadir reached of ≥30 seconds

  
  
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  Deceleration is delayed in timing—nadir occurs after peak of contraction

  
  
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  In most cases, onset, nadir, and recovery occur after the beginning, peak, and end of contraction

  
  
• 
  

  Reflect transient or chronic uteroplacental insufficiency

Variable Deceleration

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  Abrupt decrease in FHR—from the onset to FHR nadir of <30 seconds

  
  
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  Decrease in FHR is ≥15 bpm, lasting ≥15 seconds, and <2 minutes duration

  
  
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  If progress to greater depth and longer duration, more indicative of impending fetal acidemia

  
  
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  Due to cord or head compression. Can occur at any time

  
  
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  When associated with contractions, onset, depth, and duration may vary

Prolonged Deceleration

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  Visually apparent decrease in FHR below the baseline

  
  
• 
  

  Decrease in FHR is ≥15 bpm, lasting ≥2 minutes, but <10 minutes

  
  
• 
  

  If lasts ≥10 minutes or longer, it is a baseline change

Sinusoidal Pattern: Smooth, sine wave–like undulating pattern with a cycle frequency of 3–5 per minute which persists for ≥20 minutes

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  Ominous pattern; seen with chronic fetal anemia

  
  
• 
  

  Actual FHR baseline is indeterminable and baseline variability is absent/minimal

  
  
• 
  

  Pseudosinusoidal pattern seen when narcotics given in labor

Fetal Tachycardia: Potential causes: Chorioamnionitis, pyelonephritis, other maternal infections, medications (terbutaline, cocaine, stimulants), hyperthyroidism, placental abruption, fetal bleeding, fetal tachyarrhythmias

Prolonged Decelerations/Fetal Bradycardia: Potential causes: Maternal hypotension (post-epidural), umbilical cord prolapse/occlusion, rapid fetal descent, tachysystole, placental abruption, uterine rupture, congenital heart abnormalities

Minimal Variability: Potential causes: Maternal medications (opioids, magnesium sulfate), fetal sleep cycle (20–60 minutes), fetal acidemia

Three-Tier System (Table 1-12)

Management of Fetal Heart Rate Tracings

Category I

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  Reassuring

  
  
• 
  

  Continue expectant management

Category II

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  Require evaluation, continued surveillance, initiation of appropriate corrective measures, and reevaluation.

  
  
• 
  

  FHR accelerations and/or moderate variability are highly predictive of normal fetal acid–base status

Category III

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  Abnormal; increased risk for fetal acidemia

  
  
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  Associated with increased risk for neonatal encephalopathy, cerebral palsy (CP), neonatal acidosis

  
  
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  Predictive value for abnormal neurologic outcome is poor

  
  
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  If unresolved by intrauterine resuscitative measures (Table 1-13), typically requires expeditious delivery

Miscellaneous

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  Vibroacoustic stimulation (VAS): Position on maternal abdomen. Apply stimulus for 1–2 seconds. If response is not elicited, may repeat up to three times for progressively longer durations of up to 3 seconds. If acceleration of 10 beats for 10 seconds, scalp pH is at least 7.20

  
  
• 
  

  When fetal scalp stimulation is followed by an acceleration of 15 bpm lasting 15 seconds, the fetal pH value is at least 7.20

Apgar Scores (Table 1-14)

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  Clinical tool to assess clinical status of newborn and response to resuscitative measures

  
  
• 
  

  Affected by many factors: Maternal sedation, anesthesia, congenital malformations, trauma, interobserver variability, infection, cardiorespiratory conditions

  
  
• 
  

  Five-minute Apgar has prognostic significance for survival. A score of 0–3 at 5 minutes correlates with neonatal mortality but does not predict later neurologic dysfunction

  
  
• 
  

  Not intended to define asphyxia injury or predict neurological outcome; however, low Apgar scores at 5 and 10 minutes confer an increased relative risk of CP. Yet most infants with low Apgar scores will not develop CP

  
  
• 
  

  If 5-minute Apgar is ≥7, unlikely that peripartum hypoxia-ischemia played a major role in causing neonatal encephalopathy

Umbilical Cord Blood Gases

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  Umbilical cord artery metabolic acidemia has a relatively weak predictive value for longer-term complications, such as neonatal encephalopathy or CP

  
  
• 
  

  Neonatal arterial blood gases obtained within 1 hour after birth can be interpreted in a similar fashion to umbilical cord arterial blood gas samples

  
  
• 
  

  Obtaining Umbilical Cord Gases

  
  
  
  
  • 
    

    Both arterial and venous should be sampled to ensure artery has been sampled

    
    
  • 
    

    Doubly clamp cord. If delay in obtaining is more than 20 minutes, store on ice. Interpret base deficit with caution

    
    
  • 
    

    pH, Po₂, and Pco₂ values remain essentially unchanged for up to 60 minutes in clamped vessels

  
  
• 
  

  If umbilical artery pH >7.2, unlikely that intrapartum hypoxia played a role in causing neonatal encephalopathy

  
  
• 
  

  Umbilical artery pH <7.0 or base deficit ≥12.0 mmol/L increases chances that neonatal encephalopathy (if present) had an intrapartum hypoxic component

  
  
• 
  

  Base deficit 12–16 mmol/L: 10% with moderate-severe complications

  
  
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  Base deficit >16 mmol/L: 40% with moderate to severe complications

  
  
• 
  

  Is a continuum of increasing risk of neonatal encephalopathy with worsening acidemia. Even with significant acidemia, most newborns will be neurologically normal

Respiratory Distress Syndrome (RDS)

• 
  

  Primarily from a deficiency of pulmonary surfactant (produced by Type II pneumocytes), which increases surface tension, causing collapse of small alveoli and overinflation of large alveoli

  
  
• 
  

  Major cause of morbidity and mortality in preterm infants

  
  
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  Incidence (Table 1-15)

  
  
  
  
  • 
    

    Increased risk if male or Caucasian (compared with Asian, Black, Hispanic)

    
    
  • 
    

    Increased risk if delivered by CD

    
    

    Elective CD at term

    
    
    
    
    • 
      

      Compared to delivery at 39 weeks, the Odds Ratio of RDS with delivery at

      
      
      
      
      • 
        

        37 weeks is 4.2

        
        
      • 
        

        38 weeks is 2.1

  
  
• 
  

  Administration of antenatal corticosteroids reduces risk of RDS by enhancing maturational changes. (See Preterm Labor (PTL) section for more information)

  
  
  
  
  • 
    

    Reduction in RDS (relative risk: 0.66; thus 34% reduction)

    
    
  • 
    

    Reduction in moderate to severe RDS (relative risk: 0.55)

    
    
  • 
    

    In original study, maximum benefit occurred when delivered more than 48 hours but less than 7 days after administration

    
    
  • 
    

    Minimal interval between administering steroids and delivery needed to achieve benefit is not yet known

    
    
  • 
    

    Some studies suggest benefits may be seen after several hours

Fetal Lung Maturity (FLM) Testing

• 
  

  Few indications

  
  
• 
  

  May help identify a fetus at risk of RDS; however, a positive FLM test does not reliably predict other adverse outcomes

  
  
• 
  

  Even if FLM testing is mature before 39 weeks, neonate is still at higher risk of adverse outcomes than neonate delivered after 39 weeks without FLM testing

  
  
• 
  

  FLM testing should not be performed when delivery is mandated for fetal or maternal indications

  
  
• 
  

  Various tests have been used

  
  
  
  
  • 
    

    Lecithin-to-sphingomyelin (L/S) ratio

    
    
  • 
    

    Phosphatidyl-glycerol (PG)—Detection

    
    
  • 
    

    Lamellar body count

Breech Presentation (Figures 1-14 and 1-15)

Incidence

• 
  

  3–4% of term pregnancies

  
  
• 
  

  Decreases with increasing GA

  
  
• 
  

  Earlier GA with higher percentage of footling breech compared to later GA when most are frank breech

Delivery

• 
  

  “The decision regarding the mode of delivery should depend on the experience of the health care provider …. Planned vaginal delivery of a term singleton breech fetus may be reasonable under hospital-specific protocol guidelines for both eligibility and labor management” [ACOG Committee Opinion No. 340, July 2006]

Risk Factors

Breech Delivery Definitions

• 
  

  Spontaneous delivery: No traction or manipulation of fetus. Often occurs in very preterm, previable, deliveries

  
  
• 
  

  Assisted breech delivery (partial breech extraction): Most common type of vaginal breech. Fetus delivers spontaneously up to umbilicus. Maneuvers used to assist in the delivery of the remainder of the body, arms, and head

  
  
• 
  

  Total breech extraction: Feet grasped; entire fetus extracted. Ideally, it should be used only for second twin; not singleton as cervix may not be dilated to allow passage of head

Maneuvers for Breech Delivery

• 
  

  Leave fetal membranes intact as long as possible to act as dilating wedge and prevent cord prolapse

  
  
• 
  

  Do not exert traction until fetal umbilicus is past perineum

  
  
• 
  

  Pinard maneuver may be needed to deliver legs (after fetal umbilicus reached). Exert pressure in popliteal space of knee and flex knee; guide thigh away from trunk as trunk is rotated in opposite direction (Figure 1-16)

  
  
• 
  

  With thumbs over sacrum and fingers resting on anterior superior iliac crests (to minimize soft tissue injury), apply gentle, steady downward/outward traction until scapulae are visible (Figure 1-17)

  
  
• 
  

  Maternal expulsive efforts will assist

  
  
• 
  

  Lovsett maneuver to deliver extended or nuchal arms. Slide 2 fingers along humerus until elbow is reached. Sweep forearm across chest and out of vagina

  
  
• 
  

  Mauriceau-Smellie-Veit maneuver: May be needed to deliver fetal head.

  
  
  
  
  • 
    

    Principle is traction down the axis of the birth canal and flexion of the fetal head (Figure 1-18)

    
    
  • 
    

    Index and middle finger on fetal maxilla

  
  
• 
  

  During delivery of the head, avoid extreme elevation of the body, which may result in hyperextension of the cervical spine and potential neurologic injury

Entrapment of the Aftercoming Head

• 
  

  Consider IV nitroglycerin (50–100 μg)

  
  
• 
  

  Dührssen Incisions: See Figure 1-19. Bandage scissors used to make one to three incisions extending the full length of the cervical lip, typically at 2 and 10 o’clock, possibly 6 o’clock also. Incisions may extend into lower uterine segment or broad ligament and may injure uterine vessels, ureter, and bladder

  
  
• 
  

  Piper Forceps: Designed to deliver the aftercoming head. See Figure 1-20

Complete Breech Extraction

• 
  

  Grasp one or both (preferably) feet (Figure 1-21)

  
  
• 
  

  Apply traction on feet and ankles

  
  
• 
  

  Gentle downward traction until hips are delivered

  
  
• 
  

  Deliver with typical breech maneuvers

Face/Brow Presentation

Associated with multiparity, cephalopelvic disproportion, fetal anomalies (anencephaly, anterior neck mass), macrosomia, platypelloid pelvis, prematurity, and PPROM.

Face Presentation

• 
  

  Occurs in 1:500 live births

  
  
• 
  

  Majority in mentum anterior position (about 60%)

  
  
• 
  

  Approximately 26% will be in mentum posterior position

  
  
• 
  

  Nearly one-third to one-half in mentum transverse and mentum posterior positions will spontaneously convert to mentum anterior position during labor

  
  
• 
  

  Only mentum anterior are likely to deliver vaginally. As chin passes under symphysis, slight flexion may occur

  
  
• 
  

  Persistent mentum posterior will not deliver vaginally (unless very preterm). CD is indicated

Brow Presentation

• 
  

  Occurs in about 1:500 to 1:1500 deliveries

  
  
• 
  

  If persistent, not compatible with vaginal birth unless fetus is very small

  
  
  
  
  • 
    

    50% will spontaneously convert to face or vertex presentation. Labor may progress with careful monitoring. Deliver by CD if arrest of progress

External Cephalic Version (ECV)

• 
  

  Women near term with breech presentation should be offered version attempt

  
  
• 
  

  Best GA to perform: Most common GA in trials is about 36 weeks. Per ACOG (Practice Bulletin No. 13, 2000), preferred candidates have completed 36 weeks of gestation (ie, may do at 36-0/7)

  
  
• 
  

  Needs to be performed in a facility with access to CD

  
  
• 
  

  Successful in 35–86%; average 58%

  
  
• 
  

  Short-term fetal bradycardia may be seen in more than 20%, but urgent CD for nonreassuring FHR occurs in less than 1% (1:600)

  
  
• 
  

  Tocolysis: Terbutaline 0.25 mg subcutaneously 5–10 minutes prior to procedure may increase success

  
  
• 
  

  Anesthesia: Conflicting evidence. A meta-analysis suggested success rates were higher with regional anesthesia (59.7% compared with 37.6%)

  
  
• 
  

  NST should be performed before and after procedure

  
  
• 
  

  No evidence is available to support immediate IOL after successful ECV

  
  
• 
  

  Contraindications: The usual contraindications to vaginal birth (ie, placenta previa, prior classical CD vasa previa)

  
  
• 
  

  Relative contraindications: Ruptured membranes, oligohydramnios, known uterine or fetal anomaly, unexplained uterine bleeding, active labor

  
  
• 
  

  Previous low segment transverse CD is NOT a contraindication. Similar success rates, but limited data on safety of procedure