Description
This academic presentation outlines the Mechanism of Labour, authored by Dr Kenneth Chanda, a specialist with a Bachelor of Science in Human Biology, Bachelor of Medicine and Bachelor of Surgery, and a Master of Medicine in Obstetrics and Gynaecology from the University of Zambia. Created for a BSc in Clinical Medicine program, the material provides a clear definition of normal labour and details the sequential biomechanical adaptations the fetus undergoes to navigate the birth canal. It explains key terms such as lie, presenting part, and engagement, and systematically describes the cardinal movements: descent, flexion, internal rotation, extension, restitution, external rotation, and final delivery. The resource uses the mnemonic EDFIERED to summarise this critical physiological process, making it an excellent revision tool for tertiary-level medical, nursing, and midwifery students in Zambia. This structured overview is essential for exam preparation and for building a foundational understanding of obstetric mechanics. Access these notes to consolidate your knowledge of normal labour progression.
What's inside
Mechanism of Labour BSc. Clinical Medicine Dr Kenneth Chanda BScHB, MBChB, MMed (MMOG)-[UNZA] First version: 07-11-17 Latest version: 07-11-17 Mechanism of Normal Labour Dfn: Series of changes in position & attitude which the fetus undergoes during its passage through the birth canal Labour is onset of painful regular contractions, more than 1 every 10 min, with progressive cervical effacement & dilatation with descent of presenting part Head enters brim through the available transverse diameter of the inlet (70%) The Passage The Passenger Description of terms The lie The relation which the fetus bears to the longitudinal axis of the uterus May be Longitudinal, Oblique or Transverse Presenting part The part of the fetus which is in or over the pelvic brim and in relation to the cervix Engagement The widest diameter of the presenting part (with a well-flexed head, where the largest transverse diameter of the fetal occiput is the biparietal diameter) enters the maternal pelvis to a level below the plane of the pelvic inlet On pelvic examination, the presenting part is at 0 station, or at the level of the maternal ischial spines (Or 2/5 abdominally) Lightening-engagement before labour in PGs Descent Downward movement through pelvic inlet through dilated cervix, reaches posterior vaginal wall Slow in the first stage but pronounced in the second stage Completed with expulsion of fetus Due to contraction and retraction of uterine muscles (primary force) plus bearing down efforts (secondary force) in second stage Descent (Cont’d) Flexion Flexion is a passive movement in part due to surrounding structure Achieved either due to the resistance offered by the unfolding cervix, the walls of the pelvis or by the pelvic floor It is essential for descent as it reduces the shape and size of the plane of the advancing diameter of the head Internal rotation Internal rotation (Cont’d) Extension Extension leads to delivery of the head Occiput escapes from underneath the symphysis pubis and distends the vulva (Crowning of the heard) Further extension with pubic symphysis acting as fulcrum on the occiput leads to appearance of bregma, face and chin in succession Minimises soft tissue trauma Restitution, External Rotation & Delivery Restitution is the slight rotation of the occiput through one eighth of the circle Allows aligning of the head with the shoulders which entered pelvis in a slight oblique position External rotation aligns the shoulders into directly anterior-posterior plane Rest of body delivers spontaneously Delivery of the shoulders Summary Mechanism of labour involves (EDFIERED) Engagement Descent Flexion Internal rotation Extension Restitution External rotation Delivery of shoulders and body THE END
An extract of the text. Open the file below to read the full document.