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Labor Review. Petrenko N., MD,PhD. Critical Factors in Labor. 5 critical factors Birth passage Fetus Relationship of Maternal Pelvis and Presenting Part Physiologic forces of labor Psychosocial considerations. 1 Birth Passage. Four different types of pelvises, but frequently mixed types.
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Labor Review Petrenko N., MD,PhD
Critical Factors in Labor • 5 critical factors • Birth passage • Fetus • Relationship of Maternal Pelvis and Presenting Part • Physiologic forces of labor • Psychosocial considerations
1 Birth Passage • Four different types of pelvises, but frequently mixed types anthrapoid android gynaecoid platypelloid
2 Fetus Lambdoidal suture • Sutures: • Frontal • Sagittal • Coronal • Lambdoidal Sagittal suture Coronal suture Frontal suture Note: sutures are actually membranous spaces that meet at fontanels
Fetus • ☺Fontanelles: intersection of sutures, allows for molding, helps identify position of head • Anterior (bregma) • Diamond shaped • Approx 2-3 cm • Ossifies in ~12-18 months • Posterior • Triangle shaped • Smaller • Closes in 8-12 weeks
Fetus • Other landmarks on the fetal head • Mentum • Sinciput • Vertex • occiput
Fetus • Fetal attitude • Relation of fetal parts to one another • Normal: mod flexion of head, flexion of arms onto chest, flexion of legs onto abdomen • Changes in attitude can contribute to longer, more difficult labor or Cesarean Section
Fetus • Fetal lie • Relationship of the spine (cephalocaudal axis) of the fetus to the spine of the mom • Longitudinal: parallel • Transverse: right angle • Oblique: acute abgle
Fetus Fetal lie Longitudinal Transverse
Fetus • Fetal presentation • Body part entering the pelvis (presenting part) • Cephalic • Breech • Shoulder
Fetus Fetal lie Cephalic • Breech Shoulder
Fetus • Fetal presentation: Cephalic • ☺Vertex presentation • Most common • Head completely flexed on chest • Suboccipitobregmatic (Smallest diameter) • Occiput in presenting part
Fetus • Fetal presentation: Cephalic • Military presentation • Fetal head neither flexed nor extended • Occipitofrontal diameter presents • Top of the head is presenting part
Fetus • Fetal presentation: Cephalic • Brow presentation • Fetal head partially extended • Occipitomental diameter presents • Sinciput is presenting part
Fetus • Fetal presentation: Cephalic • Face presentation • Head hyperextended • Submentobregmatic diameter presents • Face is presenting part
Fetus • Fetal presentation: Breech • Sacrum is the landmark • Complete breech • Knees and hips are flexed, thighs on abdomen (“fetal position”) • Buttocks and feet are presenting parts
Fetus • Fetal presentation: Breech • Sacrum is the landmark • Frank breech • Hips flexed, knees extended • Buttocks is presenting part
Fetus • Fetal presentation: Breech • Sacrum is the landmark • Footling breech • Hips and legs extended • Feet are presenting parts (single vs double)
Fetus • Fetal presentation: Shoulder • Acromion process of shoulder is presenting part
Station In Gynaecoid & Android pelvis distance between ischial spine to brim is ~5 cm. In Anthropoid pelvis distance is ~7 cm In Platypelloid pelvis distance is ~3 cm Station of the head in relation to ischial spines
Relationship of maternal pelvis and presenting part • OA most common, easiest to deliver • Other positions are considered malpositions • Position influences labor and birth • Largest diameter in posterior position: back pain, longer 2nd stage • Can tell position by palpation of abdomen and Vaginal Examination
2 Fetus Lambdoidal suture • Sutures: • Frontal • Sagittal • Coronal • Lambdoidal Sagittal suture Coronal suture Frontal suture Note: sutures are actually membranous spaces that meet at fontanels
Fetus • ☺Fontanelles: intersection of sutures, allows for molding, helps identify position of head • Anterior (bregma) • Diamond shaped • Approx 2-3 cm • Ossifies in ~12-18 months • Posterior • Triangle shaped • Smaller • Closes in 8-12 weeks
Fetus • Other landmarks on the fetal head • Mentum • Sinciput • Vertex • occiput
Fetus • Fetal attitude • Relation of fetal parts to one another • Normal: mod flexion of head, flexion of arms onto chest, flexion of legs onto abdomen • Changes in attitude can contribute to longer, more difficult labor or Cesarean Section
Fetus • Fetal lie • Relationship of the spine (cephalocaudal axis) of the fetus to the spine of the mom • Longitudinal: parallel • Transverse: right angle • Oblique: acute abgle
Fetus Fetal lie Longitudinal Transverse
Fetus • Fetal presentation • Body part entering the pelvis (presenting part) • Cephalic • Breech • Shoulder
Fetus Fetal lie Cephalic • Breech Shoulder
Fetus • Fetal presentation: Cephalic • ☺Vertex presentation • Most common • Head completely flexed on chest • Suboccipitobregmatic (Smallest diameter) • Occiput in presenting part
Fetus • Fetal presentation: Cephalic • Military presentation • Fetal head neither flexed nor extended • Occipitofrontal diameter presents • Top of the head is presenting part
Fetus • Fetal presentation: Cephalic • Brow presentation • Fetal head partially extended • Occipitomental diameter presents • Sinciput is presenting part
Fetus • Fetal presentation: Cephalic • Face presentation • Head hyperextended • Submentobregmatic diameter presents • Face is presenting part
Fetus • Fetal presentation: Breech • Sacrum is the landmark • Complete breech • Knees and hips are flexed, thighs on abdomen (“fetal position”) • Buttocks and feet are presenting parts
Fetus • Fetal presentation: Breech • Sacrum is the landmark • Frank breech • Hips flexed, knees extended • Buttocks is presenting part
Fetus • Fetal presentation: Breech • Sacrum is the landmark • Footling breech • Hips and legs extended • Feet are presenting parts (single vs double)
Fetus • Fetal presentation: Shoulder • Acromion process of shoulder is presenting part
Station In Gynaecoid & Android pelvis distance between ischial spine to brim is ~5 cm. In Anthropoid pelvis distance is ~7 cm In Platypelloid pelvis distance is ~3 cm Station of the head in relation to ischial spines
Relationship of maternal pelvis and presenting part • OA most common, easiest to deliver • Other positions are considered malpositions • Position influences labor and birth • Largest diameter in posterior position: back pain, longer 2nd stage • Can tell position by palpation of abdomen and Vaginal Examination
Physiologic forces of labor • Primary: uterine muscles (causes dilation and effacement) • Secondary: abdominal muscles (for 2nd stage)
Physiologic forces of labor • Phases of contractions • Increment • Acme • Decrement • Relaxation • Uterine muscle rest • Rest for mom • Restores oxygenation to baby
Physiologic forces of labor Frequency Duration Intensity
Physiologic forces of labor Intensity: indirect (subjective): palpation: mild, moderate, strong, direct (objective): mmHg pressure with IUPC (intauterine)