B6 M1 Case 2 TG

• Preterm birth


  Delivery before 37 completed weeks but beyond 20 weeks gestation
• Premature


  Neonate that has the function expected of a newborn with AOG < 37 weeks. Problems of underdevelopment of organ functions are present.
• Premature rupture of membranes (PROM)

  Rupture of membranes at any time before the onset of labor irrespective of the duration of pregnancy at the time of rupture

  
• Preterm premature rupture of membranes (PPROM)

  Rupture of membranes remote from term

  
• Braxton Hicks contractions


  Differential diagnosis for preterm labor
• Causes of preterm birth

  • INDICATED - Preeclampsia, Fetal Distress, Fetal Growth Restriction, Abruptio Placenta, Intrauterine Fetal Death
  • SPONTANEOUS - Placenta Previa or Abruption, Amniotic Fluid Infection, Immunological - APAS, Cervical Incompetence, Uterine - anomaly, fibroid, Maternal - PIH, drug abuse, Trauma or surgery, Fetal Anomalies
• Antecedents and contributing factors for preterm birth

  • Threatened Abortion - bleeding early in pregnancy
  • Lifestyle Factors - Cigarette smoking, Inadequate maternal weight gain, Young or advanced maternal age, Illicit drug use, Occupational factors, Stress
  • Genetic Factors
  • Chorioamnionitis - Intrauterine infections
• Risk factors for spontaneous preterm labor


  • Prior Preterm Birth
  • Incompetent Cervix
  • Cervical dilatation
  • Signs and symptoms - Pelvic pressure, Menstrual-like cramps, Watery vaginal discharge, Lower back pain
  • Fetal Fibronectin
  • Bacterial Vaginosis
  • Lower genital tract infection - Trichomonas, Candida, Chlamydia
  • Salivary estriol
  • Priodontal disease

  
• Management of preterm labor with intact fetal membranes

  1. Amniocentesis to detect infection

  2. Glucocorticoid Therapy - to enhance fetal lung maturation

  3. Interventions to delay preterm birth - Antimicrobials, Bed rest, Hydration and sedation, Tocolytics - Beta-adrenergic Receptor Agonists, Magnesium sulfate, Prostaglandin Inhibitors, Calcium Channel Blockers

  4. Prevention of neonatal Group B Streptococcal Infection

  
• Management of preterm labor with ruptured fetal membranes

  1. Sterile speculum exam

  2. Ultrasound

  3. If >34 weeks and in labor - allow to progress

  4. If >34 weeks and not in labor - oxytocin induction of labor

  5. If 34 weeks or < and no maternal or fetal indications for delivery - Close observation with continuous electronic fetal monitoring

  6. Corticosteroids

  7. Antibiotics

  
• Dizygotic or Fraternal twins


  Result from fertilization of two separate ova
• Monozygotic or Identical twins


  Arise from a single fertilized ovum that subsequently divides into two similar structures, each with the potential for developing into a separate individual
• Types of multifetal gestation based on placentation and amnionicity

  • Dichorionic-diamnionic
  • Monochorionic-diamnionic
  • Monochorionic-monoamnionic
  • Monochrorionic-monoamnionic
• Factors affecting incidence of multifetal gestation

  • Race
  • Heredity
  • Maternal Age and Parity
  • Maternal size and nutrition
  • Pituitary Gonadotropin
  • Infertility Therapy (Ovulation Induction Drugs)
• Methods of determination of zygosity

  • Ultrasound
  • Placental Examination
  • Infant gender
• Diagnostic tools for identification of multifetal gestation

  • History
  • Physical Examination
  • Ultrasonography
  • Other aids - Radiography, Biochemical tests, MRI
• Maternal adaptations in multifetal compared to singleton pregnancy

  • Nausea and vomiting
  • Maternal blood volume expansion
  • Red cell mass increase
  • Iron and folate requirements
  • Cardiac function
  • Blood pressure changes
  • Uterine growth
  • Maternal renal function
• Obstetric complications in multifetal gestation

  • Maternal complications - Symptoms from marked abdominal enlargement, Increased incidence of PIH, Increased incidence of Iron deficiency anemia
  • Fetal complications - Preterm birth, Intrauterine growth restriction, Congenital anomalies, Twin-twin transfusion syndrome, Cord entanglement, Discordant growth, Fetal death
• Twins and is particularly helpful in cases of conjoined twins
• Enumerate the differences in maternal adaptations in multifetal compared to singleton pregnancy

  1. Nausea and vomiting — more pronounced

  2. Maternal blood volume expansion — greater, 50-60%

  3. Red cell mass increase — proportionately less than in singletons resulting in more pronounced physiological anemia

  4. Iron and folate requirements — higher

  5. Cardiac function — cardiac output increased by 20% compared to singletons due to greater stroke volume and increased heart rate

  6. Blood pressure changes — lower diastolic BP at 20 weeks compared to singleton but higher by delivery by at least 15 mmHg

  7. Uterine growth — increased

  8. Maternal renal function — impaired especially in those complicated by hydramnios, most likely due to obstructive uropathy
• Obstetric complications that accompany multifetal gestation

  • Maternal complications:
  • Symptoms from marked abdominal enlargement
  • Increased incidence of PIH
  • Increased incidence of Iron deficiency anemia
  • Placenta previa
  • Abruptio placenta
  • Postpartum hemorrhage
  • Fetal malpresentation
  • Fetal/Neonatal complications:
  • Abortion
  • Malformations:
  • Defects from twinning itself — conjoined, acardiac, sirenomelia, neural tube defects, holoprosencephaly
  • Defects from vascular interchange between monochorionic twins — microcephaly, hydrancencephaly, intestinal atresia, aplasia cutis, limb amputation
  • Defects from overcrowding — Talipes, congenital hip dislocation
  • Low birthweight
  • Preterm birth — mean gestational age for twins in 35 weeks and for triplets, 32 weeks
• Unique complications of multifetal gestation

  • Monoamniotic twinning: Intertwining of umbilical cords — common cause of death
  • Conjoined fetal twins: thoracopagus (anterior), pygopagus (posterior), craniopagus (cephalic), ischiopagus (caudal)
  • Acardiac twin – Twin Reversed-Arterial Perfusion (TRAP) sequence
  • Vascular anatomoses – most are hemodynamically balanced and of little fetal consequence but in others, this can cause hemodynamically significant shunts between fetuses leading to acardiac twinning or twin-to-twin transfusion syndrome
  • Twin-to-Twin Transfusion Syndrome (TTTS) — blood is transfused from donor twin to recipient sibling such that donor becomes anemic and growth restricted and recipient becomes polycythemic and may develop circulatory overload manifesting as hydrops and heart failure
  • Discordant twins – size inequality. Accumulated data suggest that weight discordancy greater than 25-30% most accurately predicts perinatal outcome
• Management of multifetal gestation


  • ANTEPARTUM:
  • Goals of antepartum care:
  • Prevent the delivery of markedly preterm infants
  • Identify failure of one or both fetuses to thrive and deliver fetuses so afflicted before they become moribund
  • Eliminate fetal trauma during labor and delivery
  • Provide expert neonatal care
  • Maternal diet:
  • Increased requirements
  • Weight gain based on prepregnancy weight
  • Iron and folic acid supplementation
  • Maternal medical problems — BP monitoring
  • Fetal Surveillance:
  • Serial sonography –3rd trimester
  • Tests of fetal health:
  • Non-stress test
  • Biophysical profile
  • Doppler velocimetry
  • Management of complications:
  • Hydramnios – amniocentesis
  • Preterm Labor:
  • Bed rest
  • Tocolytics – risky
  • Corticosteroids
  • INTRAPARTUM:
  • Recommendations for intrapartum management:
  • Continuous electronic fetal monitoring
  • Blood available for transfusion
  • Intravenous fluid
  • Prophylactic antibiotics in preterm labor
  • Vaginal delivery:
  • cephalic-cephalic
  • labor induction – not contraindicated; warrants special attention
  • collision
  • Caesarean Delivery:
  • noncephalic 1st twin
  • interlocking twins (breech – cephalic)
  • high order multifetal pregnancy
• Fetal growth restriction


  Birthweight below the 5th percentile or below the 10th percentile (small for gestational age)
• Theories on pathophysiology of Fetal Growth Restriction

  • Symmetrical: proportionally small - early insult could theoretically result in relative decrease in cell number as well as cell size
  • Asymmetrical: disproportionately lagging abdominal growth - late pregnancy insult, such as placental insufficiency, theoretically could primarily affect cell size
• Risk factors that predispose to FGR


  • Constitutionally small mothers
  • Poor maternal weight gain and nutrition
  • Social Deprivation
  • Fetal Infections
  • Congenital malformations
  • Chromosomal abnormalities
  • Primary disorders of cartilage and bone
  • Chemical teratogens
  • Vascular Diseases
  • Chronic Renal Disease
  • Chronic Hypoxia
• Fetal growth restriction (FGR)


  Condition where a fetus is smaller than expected for the gestational age
• 30% incidence in fetuses whose mothers are heavy drinkers (5 or more drinks per day)
• Vascular diseases


  • Chronic vascular disease, especially when further complicated by superimposed preeclampsia, commonly causes growth restriction
  • Preeclampsia itself may cause fetal growth failure
  • Abnormal vascular response is often seen in women with preeclampsia even before the manifestations of overt hypertension, and occasionally an already growth-restricted fetus is associated with recent-onset preeclampsia
• Chronic renal disease


  • Renal insufficiency may be accompanied by restricted fetal growth
• Chronic hypoxia


  • When exposed to a chronically hypoxic environment, some fetuses have significant reduction in birthweight
  • Fetuses of women who reside at high altitude usually weigh less than those born to women who live at a lower altitude
  • Fetuses of women with cyanotic heart disease are also frequently growth restricted
• Maternal anemia


  • Maternal anemia generally does not cause growth restriction except in those with sickle cell disease or with other inherited anemias associated with serious maternal disease
  • Deficient in maternal total blood volume early in pregnancy has been linked to fetal growth restriction
• Placental and cord abnormalities

  • Chronic partial placental separation, extensive infarction or chorioangioma are likely to cause restricted fetal growth
  • Marginal insertion of the cord and especially velamentous insertions are more likely to be accompanied by a growth-restricted fetus
  • Many cases of fetal growth restriction are in pregnancies with apparently normal fetuses whose placentas are grossly normal. The cause of growth failure in these cases is often presumed to be uteroplacental insufficiency
• Multiple fetuses


  • Pregnancy with 2 or more fetuses is more likely to be complicated by abnormal growth of one or both fetuses compared with normal singletons
• Antiphospholipid antibody syndrome


  • Adverse obstetrical outcomes including feta-growth restriction have been associated with 3 species of antiphospholipid antibodies: anticariolipin antibodies, lupus anticoagulant, and antibodies against beta-2-glycoprotein-I
  • Pregnancy outcome in women with these antibodies is often poor, and may also involve early-onset preeclampsia and 2nd or 3rd trimester fetal demise
  • Maternal morbidity due to vascular thrombotic evens is not uncommon
• Extrauterine pregnancy


  • The fetus gestated outside the uterus is usually growth restricted
• Complications associated with FGR


  • Fetal demise
  • Birth asphyxia
  • Meconium aspiration
  • Neonatal hypoglycemia
  • Hypothermia
  • Prevalence of abnormal neurologic development
• Screening methods to identify FGR

  1. Identification of risk factors

  2. Early establishment of gestational age

  3. Attention to maternal weight gain

  4. Fundic height measurements

  5. Ultrasonic measurements

  6. Doppler velocimetry in fetal growth restriction
• Management of FGR near term

  1. Prompt delivery is likely to afford the best outcome for the fetus who is considered growth restricted at or near term

  2. In the presence of significant oligohydramnios, most fetuses will be delivered if gestational age has reached 34 weeks or beyond

  3. With reassuring fetal heart rate pattern, vaginal delivery may be attempted
• Management of FGR remote from term

  1. When growth restriction is diagnosed in an anatomically normal fetus prior to 34 weeks, and amniotic fluid volume and antepartum fetal surveillance is normal, observation is recommended

  2. As long as there is continued growth and fetal evaluation remains normal, the pregnancy is allowed to continue until fetal maturity is achieved; otherwise, delivery is effected

  3. Amniocentesis for assessment of pulmonary maturity may be helpful in clinical decision making

  4. Sonography is repeated at intervals of 2 to 3 weeks

  5. No specific treatment will ameliorate the condition