THE INTRAPARTAL EXPERIENCE

General overview: This review of the anatomical and physiological determinants of successful labor provides baseline data against which the nurse compares findings of an ongoing assessment of the woman in labor. Nursing actions are planned and implemented to meet the present and emerging needs of the woman in labor.
  1. Biologic foundations of labor
    1. Premonitory signs
      1. Lightening-process in which the fetus “drops” into the pelvic inlet.
        1. Characteristics
          1. Nullipara-usually occurs 2-3 weeks before onset of labor.
          2. Multipara-commonly occurs with onset of labor.
        2. Effects
          1. Relieves pressure on diaphragm- breathing is easier.
          2. Increases pelvic pressure.
            1. Urinary frequency returns.
            2. Increased pressure on thighs.
            3. Increased tendency to vulvar, vaginal, perianal, and leg varicosities.
      2. Braxton-Hicks contractions-may become more uncomfortable.
    2. Etiology: unknown. Theories include:
      1. Uterine overdistention.
      2. Placental aging-declining estrogen/progesterone levels.
      3. Rising prostaglandin level.
      4. Fetal cortisol secretion.
      5. Maternal/fetal oxytocin secretion.
    3. Overview of labor process-forces of labor (involuntary uterine contractions) overcome cervical resistance; cervix thins and opens (0-10 cm dilation). Voluntary contraction of secondary abdominal muscles during the second stage (pushing, bearing-down) forces fetal descent. Changing pelvic dimensions force fetal head to accommodate to the birth canal by molding (cranial bones overlap to decrease head size).
        Stages of labor:
      1. First-begins with establishment of regular, rhythmic contractions; ends with complete effacement and dilation (10 cm); divided into three phases:
        1. Latent and early active.
        2. Active.
        3. Transitional.
      2. Second-begins with complete dilation and ends with birth of infant.
      3. Third-begins with birth of infant and ends with expulsion of placenta.
      4. Fourth-begins with expulsion of placenta; ends when maternal status is stable (usually 1-2 hours postpartum).
    4. Anatomical/physiological determinants
      1. Maternal
        1. Uterine contractions-involuntary; birth; begin process of involution.
          1. Characteristics: rhythmic; increasing tone , peak , relaxation .
          2. Effects:
            1. Decreases blood flow to uterus and placenta.
            2. Dilates cervix during first stage of labor.
            3. Raises maternal blood pressure during contractions.
            4. With voluntary bearing-down efforts (abdominal muscles), expels fetus (second stage) and placenta (third stage).
            5. Begins involution.
          3. Assessment:
            1. Frequency-time from beginning of one contraction to beginning of the next.
            2. Duration-time from beginning of contraction to its relaxation
            3. Strength (intensity)-resistance to indentation.
            4. False/true labor-differentiation
            5. Signs of dystocia (dysfunctional labor).
        2. Pelvic structures and configuration:
          1. False positive-above linea terminalis (line travels across top of symphysis pubis around to sacral promontory); supports gravid uterus during pregnancy.
          2. True pelvis-below linea terminalis; divided into:
            1. Inlet-“brim,” demarcated by linea terminalis.
              1. Widest diameter: transverse.
              2. Narrowest diameter: anteriorposterior (true conjugate).
            2. Midplane-pelvic cavity.
            3. Outlet.
              1. Widest diameter: anteriorposterior (requires internal rotation of fetal head for entry).
              2. Narrowest diameter: transverse (intertuberous); facilitates birth in occiput anterior (OA) position.
          3. Classifications
            1. Gynecoid-normal female pelvis; rounded oval.
            2. Android-normal male pelvis; funnel shaped.
            3. Anthropoid-oval.
            4. Platypelloid-flattened, transverse oval.
      2. Fetal
        1. Fetal head
          1. Bones-one occipital, two frontal, two parietals, two temporals.
          2. Suture-line of junction or closure between bones; sagittal (longitudinal), coronal (anterior), and lambdoidal (posterior, frontal); permit molding to accommodate head to birth canal.
          3. Fontanels-membranous space between cranial bones during fetal life and infancy.
            1. Anterior “soft spot”-diamond shaped; junction of coronal and sagittal sutures; closes (ossifies) by 18 months.
            2. Posterior-triangular; junction of sagittal and lambdoidal sutures; closes by 4 months of age.
        2. Fetal lie-relationship of fetal long axis to maternal long axis (spine).
          1. Transverse-shoulder presents.
          2. Longitudinal-vertex or breech presents.
        3. Presentation-fetal part entering inlet first.
          1. Cephalic-vertex (most common); face, brow.
          2. Breech
            1. Complete-feet and legs flexed on thighs; buttocks and feet presenting
            2. Frank-legs extended on torso, feet up by shoulders; buttocks presenting.
            3. Footling-single   (one foot), double (both feet) presenting.
        4. Attitude-relationship of fetal parts to one another (head flexed on chest).
        5. Position-relationship of presenting fetal part to quadrants of maternal pelvis; vertex most common, occiput anterior on maternal left side (LOA).
      3. Assessment: determine presentation and position.
        1. Leopold’s maneuvers-abdominal palpation.
          1. First-palms over fundus, breech feels softer, not as round as head would be.
          2. Second-palms on either side of abdomen, locates fetal back and small parts.
          3. Third-fingers just above pubic symphysis, grasp lower abdomen; if unengaged, presenting part is mobile.
          4. Fourth-facing mother’s feet, run palms down sides of abdomen to symphysis; check for cephalic prominence (usually on right side), and if head is floating or engaged.
        2. Location of fetal heart tones-heard best through fetal back or chest.
          1. Breech presentation-usually most audible above maternal umbilicus.
          2. Vertex presentation-usually most audible below maternal umbilicus.
          3. Changing location of most audible FHTs (fetal heart tones)-useful indicator of fetal descent.
          4. Factors affecting audibility:
            1. Obesity.
            2. Maternal position.
            3. Polyhydramnios.
            4. Maternal gastrointestinal activity.
            5. Loud uterine bruit-origin: hissing of blood through maternal uterine arteries; synchronous with maternal pulse
            6. Loud funic souffle-origin: hissing of blood through umbilical arteries; synchronous with fetal heart rate (FHR).
            7. External noise, faulty equipment.
        3. Vaginal examination: palpable sutures, fontanels (triangular-shaped superior, diamond-shaped inferior=vertex presentation, OA position).
      4. Cardinal movements of the mechanisms of normal labor-vertex presentation, positional changes of fetal head accommodate to changing diameters of maternal pelvis.
        1. Descent-head engages and proceeds down birth canal.
        2. Flexion-head bent to chest; presents smallest diameter of vertex (suboccipitalbregmatic).
        3. Internal rotation-during second stage of labor, transverse diameter of fetal head enters pelvis; occiput rotates 90 degrees to bring back of neck under symphysis (LOT to LOA to OA); presents smallest diameter (biparietal) to smallest diameter of outlet (intertuberous).
        4. Extension-back of neck pivots under symphysis, allows head to be born by extension.
        5. Restitution-head returns to normal alignment with shoulders (with LOA, results in head facing right thigh), presents smallest diameter of shoulders to outlet.
        6. Delivery of head-shoulders in anteriorposterior position.
        7. Expulsion-birth of neonate completed.
      5. Assessment: relationship of fetal head to ischial spines (degree of descent).
        1. Engagement-widest diameter of presenting part has passed through pelvic inlet (biparietal diameter of fetal head).
        2. Station-relationship of presenting part to ischial spines (IS).
          1. Floating-presenting part above inlet, in false pelvis.
          2. Station-(-5) is at inlet (presenting part well above IS).
          3. Station 0-presenting part at IS (engaged).
          4. Station (+4)-presenting part at the outlet.
    5. Warning signs during labor
      1. Contraction-hypertonic, poor relaxation, or tetanic (greater than 90 seconds long and 22 minutes apart).
      2. Abdominal pain-sharp, rigid abdomen
      3. Vaginal bleeding-profiise.
      4. FHR-late decelerations, prolonged variable decelerations, bradycardia, tachycardia, decreased variability.
      5. Maternal hypertension.
      6. Meconium-stained amniotic fluid (MSAF).
      7. Prolonged ROM.