Fetal Lie, Presentation, Attitude, and Position

Fetal Lie and Presentation

• The fetal lie refers to the long axis of the fetus in relation to the mother.
• Fetal presentation is the part of the fetus that enters the maternal pelvis first and occupies the lower segment.

Types of Fetal Presentation

• Breech presentation: complete, footling, or shoulder/hand.
• Cephalic presentation: vertex, face, or brow.

Presenting Diameters

• Average term infant: cephalic presentation (e.g., vertex, face, or brow).

Fetal Position and Attitude

• Fetal position: the relationship of the denominator to the four quadrants of the pelvis.
• Fetal attitude: the descent of the fetal head.

Mechanism of Labour

• The process of labour involves engagement, descent, flexion, internal rotation, extension, and external rotation.
• Occipito-anterior is the most common mechanism of labour.

Cervical Softening and Dilatation

• Cervical softening: disarray of collagen fibres, increased hydrophilic GAGs, and proteolytic enzyme digestion of collagen.
• Cervical dilatation: the gradual opening of the cervix.

Symptoms of Labour Onset

• "Show" (mucous plug and small amount of blood).
• Contractions: increase in intensity and frequency.
• Spontaneous rupture of membranes.

Labour Stages

• First stage: from onset of regular uterine contractions to full cervical dilatation.
• Second stage: from full cervical dilatation to delivery of the baby.
• Third stage: from delivery of the baby to delivery of the placenta.

First Stage of Labour

• Latent phase: from onset of labour to 3/4/5 cm dilatation (depending on the partogram used).
• Active phase: from 3/4/5 cm dilatation to full dilatation.
• Monitoring: maternal condition, fetal condition, and progress of labour.

Monitoring Labour

• Maternal condition: initial full assessment, including history, observations, abdominal exam, and vaginal exam.
• Fetal condition: lie, presenting part, position, and fetal heart rate.
• Progress of labour: use of the partogram, fetal descent, dilatation, and effacement.

False Labour vs True Labour

• False labour: irregular intervals, long intervals, unchanged intensity, and uneffaced cervix.
• True labour: regular intervals, shortening intervals, increasing intensity, and progressive effacement and dilatation.

Partogram

• A graphic representation of labour, reflecting maternal condition, fetal condition, and progress of labour.
• Medico-legal implications: every patient, every labour, every time.

Biochemistry of Labour

• Prevention of Ca2+ influx: oxytocin, prostaglandin, and progesterone.
• Stimulation of Ca2+ influx: uterine contractions in pregnancy.
• Biochemical start of labour: prevention of Ca2+ influx, stimulation of Ca2+ influx, and electrical synchrony.

Uterine Contractions

• Individual contraction of myometrial cells.
• Braxton Hicks contractions.
• Contractions in labour: stimulation of Ca2+ influx, contraction, and retraction.
• Postpartum uterine contraction: contraction and retraction.