Ch 12 - PowerPoint

							Ch 12. Mechanisms of
              normal labor




               부산백병원 산부인과
                   R1 서 영 진
LIE, PRESENTATION,
       ATTITUDE, AND POSITION
  By abdominal palpation, vaginal examination,
   and auscultation, or by technical means
   (USG, X-ray)
  Fetal lie
   -the relation of the long axis of the fetus to
     that of the mother
    -longitudinal (99% at term)
      transverse : multipara, pl revia
                   hydramnios, Ut anomalies
      oblique: unstable (become logitudinal or
               transv.)
LIE, PRESENTATION,
       ATTITUDE, AND POSITION
  Fetal presentation
   -the foremost portion of the body of the fetus
    within the birth canal
   -can be felt through the cevix on vaginal exam.
   -longitudinal lie: head (cephalic presentation)
                      breech (breech presentation)
    transverse lie: shoulder
LIE, PRESENTATION,
       ATTITUDE, AND POSITION
 # Cephalic presentation
   -Ordinarily, the head is flexed sharply so that
    the chin is in contact with the thorax
   -the occipital fontanel is the presenting part
   -referred to as a vertex or occipital presentation
   -extended so that the occiput is in contact with the
    back : face
             sinciput (ant. fontanel or bregma)
             brow
   -sinciput, brow: transient -> vertex or blow
LIE, PRESENTATION,
       ATTITUDE, AND POSITION
 # Breech presentation
   -frank: the thighs are flexed and the legs extended
           over the anterior surface of the body

    complete: the thighs are flexed on the abdomen
              and the legs upon the thighs

   incomplete: the lowermost part is one or both feet,
                or one or both knees (footling)
LIE, PRESENTATION,
       ATTITUDE, AND POSITION
  Fetal attitude or posture
   -the fetus forms an ovoid mass that corresponds
    roughly to the shape of the uterine cavity
   -back: markedly convex
    head: flexed (chin-chest)
    thighs: flexed over the abdomen
    legs: bent at the knee
    feet: flexed (ant. surfaces of the legs) at the ankle
    arms: crossed or parallel over the thorax
   -face presentaton: concave (extended) of the
                        vertabral column
LIE, PRESENTATION,
       ATTITUDE, AND POSITION
  Fetal position
   - the relation of arbitrarily chosen portion of the
     fetal presenting part to the right or left side of
     the maternal birth canal

   - Rght vs. Left

   -vertex: occiput
    face: chin (mentum)
    sacrum: breech
    shoulder: acromion (scapula)
LIE, PRESENTATION,
       ATTITUDE, AND POSITION
  Varieties of presentation and position
   -Right(R) & Left(L)
   -anterior(A) , posterior(P) & transverse(T)
   -occiput(O), chin (mentum(M)) & sacrum(S)
   -six vatieties
LIE, PRESENTATION,
       ATTITUDE, AND POSITION
  -If transverse lie
     : anterior or posterior & superior or inferior
     : dificult by clinical examination
     : another term back up
                         back down
FREQUENCY OF THE VARIOUS
  PRESENTATION AND POSITION
  At or near term: vertex 96%
                           2/3 LOP
                    breech 3.5%
                            much greater ealrier
                            14% (GA 29~32wks)
                    face 0.3%
                    shoulder 0.4%
FREQUENCY OF THE VARIOUS
  PRESENTATION AND POSITION
  Why the term fetus usaully presents by vertex?
   -uterus: piriform shape
   -fetal head > breech
          but. poladic pole       >     cephalic pole
         (breech+ lower extremities)       (head)
                more movable

   -after GA 32wks
    amnionic fluid / fetal mass ratio : decreased
    dependent upon the piriform shape of fetus
FREQUENCY OF THE VARIOUS
  PRESENTATION AND POSITION
  -causes of breech: hydrocephalus, uterine septum,
                     extension of vertex column
                     placeta- low uterus
                              change normal shape
                     abnomal fetal muscle tone
                                    or movement
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
  Abdominal palpation- LEOPOLD MANEUVERS
   - Leopold and sporlin in 1894
   - the mother should be supine and comfortably
     positioned with her abdomen bared

   - difficult : the patient is obese
                 the placenta is anteriorly implanted
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
                First maneuver
                 -contour of the uterus
                 -fundus ~ xiphoid 거리
                 -fetal pole in the fundus
                  *breech: large
                            nodular
                  *head: hard
                          round
                          more movable
                               & ballottable
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
                Second maneuver
                 -on either side of the
                  abdomen
                 -back
                    hard ,resistance
                    ant. vs. post.
                  extremities
                    numerous small,
                    irregular and movile
                    part
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
                Third maneuver
                -using the thumb & finger
                -above symphisis pubis
                -differentiation:
                    same as first maneuver
                -engage(+): fixed
                 engage(-): movable
                -cephalic prominence
                 small part: flexion
                 back part: extension
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
                Fourth maneuver
                 -faces the mother’s feet
                 -the tips of the first
                  three fingers
                 -exert deep pressure
                  in the pelvic inlet
                 -one hand : rouned body
                  the other: descending
                 -cephalic prominence
                    vertex pre.; small side
                    face pre.: back side
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
  Vaginal examination
   - vertex presentation: position and variety
                          by suture & fontanel
   - breech presentation: sacrum & maternal ischial
                                     tuberosities

   1.two fingers are introduced into the vagina.
    differentiation of vertex, face, and breech

 2.if vertex presentation
      the posterior aspect ~ maternal symphysis
      feel sagittal suture. large & small fontanel
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
 3.by circular motion
   around the side of the head
   the other fontanel is felt and differentiated

 4.the station, or extent to which the presenting part
  has descended into the pelvis at this time

  -in face & breech presentations, error are minimized
   because the various parts are distinguished more
   readily
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
  Auscultation
   -alone does not provide reliable information
   -fetal heart sound: through the convex portion
                       vertex & breech- back
                       face- thorax
   -vertex: midway of umbilicus ~ ASIS
        OA: midline
        OT: lateral
        OP: back in the flank
    breech: above the umbilicus
DIAGNOSIS OF THE FETAL
  PRESENTATION AND POSITION
  Sonography
   -without the potential hazards of radiation
LABOR WITH
      OCCIPUT PRESENTATIONS
  In the majority of case, the vertex enters the pelvis
   with the sagittal suture in the transverse pelvic
   diameter

  LOT : 40 %
   ROT ; 20 %
    -> LOA & ROA- rotated 45 degree

   OP : 20%
        ROP > LOP
LABOR WITH
      OCCIPUT PRESENTATIONS
  Occiput anterior presentation
   -irregular pelvic shape vs.
             large dimensions of the mature fetal head
   -adaptation, accommodation

   -the cardinal movements of labor
    engagement, descent, flexion. Intermal rotation,
    extension. external rotation, expulsion
     ->a combination of movements
   -fetal ovoid-> cylinder
LABOR WITH
      OCCIPUT PRESENTATIONS
 1. Engagement
    ; BPD passes through the pelvic inlet
   -”floating” : the fetal head is freely movable above
                 the pelvic inlet at the onset of labor
   -the fetal head usually enters the pelvis inlet either
     in the transverse diameter or in one of the oblique
     diameters
   -asynclitism
     the deflection of the head to a more anterior or
     posterior position in the pelvis
LABOR WITH
      OCCIPUT PRESENTATIONS
 2. Descent
   -nullipara: engagement –bofore labor
              descent- the second stage
     multipara: descent – begins with engagement

   -pressure of the amnionic fluid
    direct pressure of the fundus upon the breech
      with contrantion
    bearing down efforts with the abdominal muscles
    extension and straightening of the fetal body
LABOR WITH
      OCCIPUT PRESENTATIONS
 3. Flexion
   - occipitofrontal
            ▼
     suboccipitobregmatic

   -chin: contact with
          the fetal thorax
LABOR WITH
      OCCIPUT PRESENTATIONS
 4. Internal rotation
   -a turning of the head by the time the head reaches
     the pelvic floor

   -the occiput gradually moves from its original
    position anteriorly toward the symphysis pubis

   -essential for the completion of labor
LABOR WITH
      OCCIPUT PRESENTATIONS
 5. Extension
   -essential to birth

   -the base of the occiput into direct contact with
    inferior margin of the symphysis pubis

   -vulvar outlet: upward & forward
LABOR WITH
      OCCIPUT PRESENTATIONS
 6. External rotation
   -after head delivery, the occiput was directed
     toward the left (original direction)

   -bisacromial diameter into relation with the
    anteroposterior diameter of the pelvic outlet

 7. Expulsion
   -ant. shoulder: under the symphysis pubis
     post. shouider: the perineum
LABOR WITH
      OCCIPUT PRESENTATIONS
  Occiput posterior position
   -the occiput has to rotate to the symohysis pubis
    through 135 degree

   -does not take place, persistent occiput posterior
CHANGES IN SHAPE
          OF THE FETAL HEAD
  Caput succedaneum
   -before complete cervical dilatation, become
    edematous and forming a swelling

   -more commonly, in the lower portion of the
    birth canal
      LOT: Rt parietal bone
      ROT: Lt parietal bone
CHANGES IN SHAPE
          OF THE FETAL HEAD
  Molding
   -the change in fetal head shape from external
    compressive forces

   -shortened suboccipitobregmatic diameter
    lengthening of the mentovertical diameter