Intrapartum Care and Fetal Monitoring

Question 1

Labor and delivery goals

Answer 1

• Safe birth for mother and baby
• Empowering experience for woman and her family
• Comfortable(???)
• Manage complications if they arise, remembering that birth is a normal, natural process, not a disease process
• Support family interaction and bonding

Question 2

clinical management - triage

Answer 2

• Time of onset of contractions, frequency, bleeding, ROM
• Med/OB hx, pregnancy complications, allergies, meds, last PO intake
• GBS status
• Vital signs, urine dip

Question 3

Group B strep

Answer 3

• Gram positive cocci that colonizes 15-30% of pregnant women (GU and GI tract)
• An important cause of illness in infants, pregnant women, and adults with underlyling medical conditions
• 70% rate of vertical transmission to fetus once membranes rupture
• The most common cause of neonatal sepsis
  
  • Babies have respiratory symptoms that resemble RDS
• Risk factors for neonatal transmission include premature delivery, prolonged ROM, maternal fever in labor, multiple gestation
• Asymptomatic in women, though some may have GBS induced UTIs
  
  • If discovered prenatally treat with antibiotics and note in chart
  • Woman with GBS bacturiuria will automatically be considered GBS+ in the 3rd trimester and not require additional testing
• GBS Management
  
  • Test all women in clinic with a vaginal and rectal swab at 35-37 weeks
  • Women who test positive are not treated prenatally
  • Offer prophylactic antibiotics in labor to decrease the rate of transmission to the baby
    
    • PCN G 5 million units IV loading dose then 2.5 mil units q 4hrs until delivery
    • Ampicillin 2 grams IV, then I gram IV q 4 hours as second choice, “four hours before delivery”
  • Indications for antibiotic prophylaxis:
    
    • Positive screening cx for GBS (vagina or rectum)
    • Positive hx of birth of an infant with early-onset GBS disease
    • GBS bacteriuria during current pregnancy
    • Unknown antepartum cx status AND
      
      • Intrapartum fever >100.4F or
      • Preterm labor < 37 weeks, or
      • Prolonged ROM >18 hours or
    • Intrapartum rapid NAAT positive for GBS
• Maternal intrapartum GBS chemoprophylaxis has resulted in a significant reduction in early onset GBS disease (>80% of cases)
• GBS positive women (treated) have 1/4000 chance of GBS disease in baby, 1/200 (if not treated intrapartum)
• In the US, widespread use of GBS screening/intrapartum abx prophylaxis has resulted in a substantial decrease in early onset GBS infections (infection within 6 days after birth)
• 1993: (Prior to active efforts at prevention) Early onset GBS infection 1.5 per 1000 births.
• 2006: 0.4 per 1000 births

Question 4

rupture of membranes

Answer 4

• Antenatally/preterm (preterm premature rupture of membranes (PPROM)) <37 wks
• At term but before the onset of labor (premature rupture of membranes (PROM))
• Spontaneously at onset of or during labor (SROM)
• Via practitioner (amniotomy or artificial rupture of membranes (AROM))

Question 5

amniotic fluids

Answer 5

• Check color, odor, presence of blood
• Meconium staining
  
  • Term or post term fetuses are developmentally able to move their bowels and may do so spontaneously causing meconium stained fluid
  • Stressed/hypoxic baby will also pass meconium
  • Occurs about 20% of the time

Question 6

meconium

Answer 6

• Thick, black-green, odorless material first demonstrable in the fetal intestine during the third month of gestation.
• Results from the accumulation of debris (desquamated cells from the intestine/skin, GI mucin, lanugo hair, fatty material from vernix caseosa), amniotic fluid, intestinal secretions, and bile pigments.
• Meconium is sterile, but may stimulate the release of cytokines/vasoactive substances leading to cardiovascular and inflammatory responses in the fetus/newborn
• Meconium Management
  
  • If light meconium, expectant management, amnioinfusion?
  • Thick or dark meconium requires peds notification
    
    • Will probably desire suctioning the nares/mouth immediately after delivery of head, before delivery of body
    • Will prepare for possible intubation immediately after delivery to visualize below the vocal cords for meconium aspiration
• Clinical significance
  
  • Meconium aspiration syndrome
    
    • Occurs 2-10% of infants born through meconium stained fluid
    • Greatest risk in postmature infants and SGA infants
    • Mechanical obstruction and chemical pneumonitis leading to serious pulmonary hypertension
    • Frequently fatal
    • May suffer long term neurological defects

Question 7

fetal monitoring

Answer 7

• Assessment of the fetus during labor is a challenging task.
• Rationale for monitoring: FHR patterns are indirect markers of the fetal cardiac and medullary responses to blood volume changes, acidemia, and hypoxemia
• Virtually all obstetrical organizations advise monitoring the FHR during labor. This position is largely based upon the experience of experts and medico-legal precedent.
• 2013 systematic review of 13 RCTs (>37,000 high and low risk women)
• Compared continuous EFM to intermittent auscultation, found no significant difference regarding:
  
  • Perinatal mortality
  • Cerebral palsy
  • Neurodevelopmental impairment at 12 months
  • Apgar scores <4 at 5 minutes
  • NICU admission
• But… Continuous EFM was associated with an extra 12 caesarean sections, and 25 operative(assisted) deliveries per 1000 births

Question 8

electronic fetal monitoring

Answer 8

• Monitors fetal well being, tolerance of labor, occurrence of uterine contractions
• Primary indicator of fetal well being per neurologic status and normal cardiac response
• Accelerations – “Accels” - a reassuring indicator of fetal well-being (fetus NOT acidotic)
• Baseline FHR 110-160bpm
• Moderate (beat to beat variability is reassuring
• May be absent due to sleep
• Decels - periodic FHR changes associated with
• contractions
  
  • Early, Late, or Variable
• Sinusoidal pattern –rare and ominous (anemia, or severe hypoxia)

Question 9

fetal heart rate deceleration patterns

Answer 9

• Early decelerations – indicator of head compression.
  
  • Returns to baseline at end of contraction
  • Not indicative of distress, normal fetal response/vagal stimulation, slowing of FHR
• Variable decelerations – indicates cord compression.
  
  • Acute fall in FHR/rapid downslope/variable recovery phase. Generally associated with favorable outcome
• Late decelerations – associated with uteroplacental insufficiency
  
  • Begins at/after peak of contraction
  • Persistent, late decels potentially ominous, requires further evaluation of fetal pH

Question 10

EFM internal monitor

Answer 10

• Fetal electrocardiogram — bipolar spiral electrode inserted into fetal scalp/second reference electrode is placed upon the maternal thigh to eliminate electrical interference.
• Detects fetal ECG) and calculates the FHR
• Very clear signal - provides accurate measurement of beat-to-beat variability, artifact kept to a minimum
• Used when the externally derived tracing is difficult to interpret because of poor technical quality. (fetus or mother is frequently changing position, multiple gestations.)

Question 11

emergency interventions for nonreassuring patterns

Answer 11

• Call for assistance
• Administer O2 via tight fitting mask
• Change maternal position (lateral or knees/chest
• Administer fluid bolus (lactated Ringer’s)
• Perform vaginal exam, fetal scalp stimulation
• Consider tocolysis for uterine tetany or hyperstimulation
• Discontinue oxytocin if used
• Consider amnioinfusion (for variable decels)
• Determine if operative intervention is warranted/how urgently

Question 12

fetal surveillance

Answer 12

• Vibroacoustic Stimulation (VAS)
• Startles baby - Should ellicit accels
• Procedure stimulates the fetus to move, shortening the duration of time needed to produce an acceleration, without compromising the predictive value of a reactive NST.
• No evidence-based standards for performing this procedure
• Can also be used intrapartum if fetus has little FHR variability to determine sleeping baby vs hypoxic
• Vibroacoustic Stimulation (VAS)
• Uses artificial larynx held at belly to startle baby into activity through sound and vibration
• Performed antepartum or intrapartum if fetus has little FHR variability to determine sleeping baby vs hypoxic
• Goal is to identify fetus at risk of intrauterine death/asphyxia
• PMH, family hx, genetic hx, psychosocial hx will all help identify risk factors
• Indications for testing include, GDM, HTN/preeclampsia, multiple gestation, decreased fetal movement, hx of prior stillbirth, increased risk for stillbirth, postdates pregnancy, amniotic fluid abnormalities, fetal growth restriction
• Fetal movement (FM) awareness, “kick counts”
• FHR, variability
• Uterine growth
• Palpable movement 17-20 weeks “quickening”, fetal movement decreases in response to hypoxia

Question 13

pulmonary maturity

Answer 13

• Amniotic Fluid Analysis (Amnio or vaginal if ROM) – Testing to determine pulmonary maturity:
  
  • biochemical tests and biophysical tests
• All are better at predicting the absence, rather than the presence, of respiratory distress
  
  • Lamellar body count (most common) –direct measurement of surfactant production
• Analyze lecithin:sphingomyelin (L:S) ratio (pulmonary secretions into amniotic fluid)
  
  • Should be 2:1 if mature
• Phosphatidyglycol (PTG) presence signifies mature (present after 35 weeks)

Question 14

fetal surveillance sonograms

Answer 14

• Confirm GA, number of fetuses, placental location, fetal growth, R/o anomalies, AFI, Doppler velocimetry
• Nuchal translucency 10-14 wks – most useful marker (trisomy 21), Turners, heart defects, cystic hygroma, single umbilical artery
• Anatomic scan
• Fetuses with abnl karyotypes often have anatomic anomalies
• Trisomy, triploidy, monosomy, 90% involve chromosomes 21, 18,13, X or Y
• Abnormal U/S markers can be associated with normal fetuses and should be correlated with prenatal diagnostic testing. Isolated “soft” markers are identified in 11-17% of normal fetuses.
• “Soft” markers include: Increased nuchal translucency, absent nasal bone, echogenic bowel, pyelectasis, shortened long bones, echogenic intracardiac focus.

Question 15

Nonstress test (NST)

Answer 15

• Most common cardiotocographic method of antepartum fetal assessment. There are no direct maternal or fetal risks from nonstress testing – does not require oxytocin or contractions
• Higher rates of FN and FP rates than CST
• Neurologically intact, oxygenated fetus will have ≥2 15 bpm each lasting ≥ 15s accelerations above baseline in 20 min of monitoring
• “Reactive” meets or exceeds criteria
• “Nonreactive” is nonreassuring finding
• Nonreactive or inconclusive usually requires f/u w/ BPP or contraction stress test (CST)

Question 16

Contraction stress test (CST)

Answer 16

• Most accurate predictor of uteroplacental insufficiency – a hypoxic fetus will demonstrate recurrent late decels
• More expensive, takes more time, high false positives
• Can be used from 26 weeks on
• Used to f/u on NST
• Can cause labor
• Uses oxytocin (pitocin) or nipple stimulation to create uterine contractions
• Criteria: 3 UCs/10 min, felt or not
• Negative (good): FHR stable, no late decels
• Positive (bad): repetitive late decels with each UC
• Equivocal: unable to obtain satisfactory tracing
• Hyperstimulation (UCs q <2 min)
• Few false negatives, many false positives

Question 17

biophysical profile (BPP)

Answer 17

• Combined with electronic fetal monitoring nonstress test (NST)
• Fully oxygenated fetus that is neurologically intact will demonstrate:
  
  • Muscle tone
  • Gross movement
  • Respiratory activity
  • And will have:
    
    • An adequate AFI
    • A reactive NST

Question 18

Rh isoimmunization

Answer 18

• Infrequently seen presently with advent of Rh immune globulin (Rhogam) antenatally and postpartum
• Still occurs in countries where prophylaxis is not widely available
• Red cells of the fetus or newborn are destroyed by maternally-derived alloantibodies
• When an Rh(D) negative mother carries an Rh(D) positive fetus
• Rh blood system consists of numerous other antigens, most commonly C, c, E, e, and G
• Ethnic variation of phenotypically Rh(D) negative:
• Basques — 30 to 35 %
• Caucasians in North America and Europe — 15 %
• African Americans — 8 %
• Africa — 4 to 6 %
• India — 5 %
• Native Americans and Inuit Eskimos — 1 to 2 %
• Japan — 0.5 %
• Thailand — 0.3 %
• China — 0.3 %
• Peripheral blood smear shows multiple spherocytes which are small, dark, dense hyperchromic red cells without central pallor (arrows). These findings are compatible with hereditary spherocytosis or autoimmune hemolytic anemia.
• Complications can be lethal or carry serious morbidity
  
  • Alloimmune hemolytic disease of the newborn (HDN) aka erythroblastis fetalis (when it is of the fetus)
  • Clinical manifestations of alloimmune HDN range from mild, self-limited hemolytic disease (eg, hyperbilirubinemia with mild to moderate anemia) to severe life-threatening anemia (eg, hydrops fetalis).
• Hyperbilirubinemia — Less severely affected infants typically present with unexpected hyperbilirubinemia within the first 24 hours of life.
• The degree of anemia varies depending upon type of HDN.
• Some infants with Rh or some minor blood group incompatibilities can present with symptomatic anemia that require RBC transfusion.
• Hydrops fetalis — Infants present with skin edema, pleural/pericardial effusion, or ascites.
• Infants with Rh(D) and some minor blood group incompatibilities, such as Kell (most immunogenic antigens after Rh and ABO blood group systems), are at risk for hydrops.
• Neonates with hydrops may present at delivery with shock/ require emergent transfusion.

Question 19

prevention with rhogam (anti-D immunoglobulin)

Answer 19

• Not given to women who are already D alloimmunized, or biologic father CONFIRMED to be Rh Negative, consider genetic counseling
• AB screen at first prenatal visit
• AB screen again at 28 wees, Prophylaxis at 28 weeks
• After possible placental trauma, SAB, induced abortion, invasive prenatal diagnostics, ectopic, TAB, fetal demise, molar pregnancy
• Within 72 hours post partum of delivery of D-positive newborn

Question 20

risk categories

Answer 20

• Antigens that cause IgM antibodies
  
  • Cannot cross placental barrier, only IgG
  • Generally innocuous
    
    • A, P(1), Le (a), M, I, IH and Sd(a)
    • Lewis antibodies and some I and IH are prevalent
    • Some Lewis have IgG component but rarely cause clinical disease

Question 21

isoimmunization

Answer 21

• Antigen poorly expressed fetal red blood cells —
  
  • Some IgG antibodies capable of causing significant hemolytic transfusion reactions in adults are not clinically important in the fetus because their corresponding antigens are not well developed at birth: Lu(b), Yt(a), and VEL
• gM antibodies to A and B develop early in life but do not cross placenta, however IgG ABO antibodies exist, particularly in group O mothers exposed to a non O fetus. Hemolysis is more a problem for neonate, not fetus. Most common in group B African-American fetuses
• Isoimmunization Management
  
  • Serial amniocentesis to check fetal effects
  • Possibly deliver before term if fetus affected
  • In severe cases, fetal transfusion
  • Antenatal care and the prevention of maternal Rh sensitization have significantly reduced the number of infants born with severe manifestations of alloimmune HDN.
  • Postnatal management for affected infants is focused on treating the anemia and hyperbilirubinemia caused by hemolysis of neonatal RBCs.

Question 22

alloantibodies

Answer 22

• High risk antigens
  
  • Responsible for the majority of HDN cases including anti-c, anti-D, anti-E and anti-Kell
  • Anti-Kell antibodies are responsible for approximately 10% of cases of severe antibody-mediated anemia in fetuses and newborns
  • Requires intrauterine or direct fetal transfusion during pregnancy or exchange transfusion postpartum