THE BONY PELVISTHE BONY PELVIS

DR. AHMED ABDULWAHABDR. AHMED ABDULWAHAB

Assistant Professor, Assistant Professor, ConsultantConsultant

OBGYN DepartmentOBGYN Department

– In women the pelvis has special In women the pelvis has special form that adapts to childbearing form that adapts to childbearing ..

– It is composed of four bones .It is composed of four bones .– The sacrum coccyx and two The sacrum coccyx and two

innominate bones ..innominate bones ..– The innominate bone is formed The innominate bone is formed

by the fusion by the fusion of the of the ilium ,ischium, and pubis ilium ,ischium, and pubis

• The true pelvis is the portion The true pelvis is the portion important in childbearing , is important in childbearing , is bounded above by promontory and bounded above by promontory and alae of the sacrum the linea alae of the sacrum the linea terminalis and the upper margin of terminalis and the upper margin of the pubic bone , and below by the the pubic bone , and below by the pelvic outlet .pelvic outlet .

• Ischial spines are of great Ischial spines are of great obstetrical importance because it is obstetrical importance because it is the shortest pelvic diameter and has the shortest pelvic diameter and has a valuable landmarks in assessing a valuable landmarks in assessing the level the level of the of the presenting part of presenting part of the fetusthe fetus

•The sacrum form the The sacrum form the posterior wall of the pelvis posterior wall of the pelvis and it is curved to and it is curved to accommodate the rotating accommodate the rotating head .head .

•The promontory may be The promontory may be felt on vaginal examination felt on vaginal examination and provide a landmark for and provide a landmark for clinical pelvimetry clinical pelvimetry

•Pelvic joints Pelvic joints

•Symphysis pubis where Symphysis pubis where pelvic bones are joined pelvic bones are joined together anteriorlytogether anteriorly

•Sacroiliac joint where Sacroiliac joint where pelvic pelvic bones are joined bones are joined posteriorly .posteriorly .

•Planes and diameters of Planes and diameters of the pelvis the pelvis

•Four imaginary planes Four imaginary planes

•1- the plane of pelvic inlet1- the plane of pelvic inlet

•2-the plane of pelvic 2-the plane of pelvic outletoutlet

•3- the plane of mid pelvis 3- the plane of mid pelvis

•4 4 ––the plane of greatest the plane of greatest pelvic dimensionspelvic dimensions

Pelvic shapesPelvic shapes•1-gynecoid pelvis the inlet is 1-gynecoid pelvis the inlet is

slightly oval or rounded , the slightly oval or rounded , the ischial spines are not ischial spines are not prominent , the pubic arch is prominent , the pubic arch is wide , sacrum is well curved .wide , sacrum is well curved .

•Android pelvis is a deep and Android pelvis is a deep and convergent with prominent convergent with prominent ischial spines , narrow sub-ischial spines , narrow sub-pubic arch and straight pubic arch and straight sacrum .sacrum .

•Pelvic inlet measurement Pelvic inlet measurement •Diagonal conjugate it is the distant Diagonal conjugate it is the distant

from the sacral promontory to the from the sacral promontory to the lower margin of the symphysis lower margin of the symphysis pubis.pubis.

•True conjugate from sacral True conjugate from sacral promontory to upper border of promontory to upper border of symphysis pubis symphysis pubis

•Obstetric conjugate from sacral Obstetric conjugate from sacral promontory to mid of posterior promontory to mid of posterior aspect of symphysis pubis aspect of symphysis pubis subtract subtract 1.5-2.0 cm 1.5-2.0 cm from diagonal conjugatefrom diagonal conjugate

•The mid pelvis at the The mid pelvis at the level of ischial spines level of ischial spines the inter- spinous the inter- spinous diameter is 10 cm .diameter is 10 cm .

•Pelvic outlet clinically it Pelvic outlet clinically it is the distant between is the distant between the ischial tuberosities the ischial tuberosities it is it is around 8.0 cm around 8.0 cm

THE FETAL SKULLTHE FETAL SKULL

• BONESBONES

• Two frontal bones separated by Two frontal bones separated by frontal suture.frontal suture.

• Two parietal bones separated by Two parietal bones separated by sagittal suture .sagittal suture .

• Two coronal sutures between frontal Two coronal sutures between frontal and parietal bones .and parietal bones .

• Two lambdoid sutures between Two lambdoid sutures between parietal and occipital bone .parietal and occipital bone .

• Sutures meet at an irregular space Sutures meet at an irregular space forms which is enclosed by a forms which is enclosed by a membrane called fontanel .membrane called fontanel .

• Anterior fontanel is a lozenge shape Anterior fontanel is a lozenge shape between the two frontal and two between the two frontal and two parietal bones usually it is opened .parietal bones usually it is opened .

• Posterior fontanel at the junction of Posterior fontanel at the junction of the two parietal bones and occipital the two parietal bones and occipital bone .bone .

• It gives an important information It gives an important information concerning presentation and position concerning presentation and position of the fetus.of the fetus.

• Fetal head diameters Fetal head diameters • Subocipoto-bregmatic 9.5 cm Subocipoto-bregmatic 9.5 cm

vertex presentation.vertex presentation.• Submento-bregmatic 9.5 cm face Submento-bregmatic 9.5 cm face

presentation.presentation.• Mento-vertical 12.5 brow Mento-vertical 12.5 brow

presentation .presentation .• Biparietal diameter 9.5cm .Biparietal diameter 9.5cm .• Occipto-frontal 10.5 cmOccipto-frontal 10.5 cm

• Occipital bone is the landmark in Occipital bone is the landmark in vertex presentation.vertex presentation.

• Mentum is landmark for face Mentum is landmark for face presentation,presentation,

• Frontal bone is land mark for Frontal bone is land mark for brow presentationbrow presentation

labourlabour

Definition.Definition.

It is the onset of painful, regularIt is the onset of painful, regular

,contractions, more than one every ,contractions, more than one every tenten

minutes. With progressive cervicalminutes. With progressive cervical

effacement and dilatationeffacement and dilatation

accompanied by descend of the fetalaccompanied by descend of the fetal

presenting part.presenting part.

Stages of laboStages of laborrLabor is divided in to three stages.Labor is divided in to three stages.

11stst stage from diagnosis of labor till stage from diagnosis of labor till full dilatation of the cervix.full dilatation of the cervix.

22ndnd stage of labor from full stage of labor from full dilatation of the cervix till dilatation of the cervix till delivery of the fetus.delivery of the fetus.

33rdrd stage from delivery of the fetus stage from delivery of the fetus until delivery of the placenta.until delivery of the placenta.

The duration of laborThe duration of labor

Primigravida about 12 hoursPrimigravida about 12 hours. . Multigravida 8.0 hoursMultigravida 8.0 hoursThe moral of most women The moral of most women deteriorate if labor is prolongeddeteriorate if labor is prolonged. .

There is greater incidence of fetal There is greater incidence of fetal hypoxia after long laborhypoxia after long labor..Greater incidence of operative Greater incidence of operative vaginal deliveryvaginal delivery..

Mechanisim of laborMechanisim of laborIt is a series of changes in position It is a series of changes in position

and attitude that the fetus and attitude that the fetus undergoes during its passage undergoes during its passage through the birth canal.through the birth canal.

ENGAGEMENT.ENGAGEMENT.It is when the widest diameter of It is when the widest diameter of

the head has passed successfully the head has passed successfully through the inlet that is when through the inlet that is when the bi-parietal diameter passed the bi-parietal diameter passed to the level of the ischial spines to the level of the ischial spines

DESCENT.DESCENT.

It is secondary to uterine action It is secondary to uterine action in 1in 1stst and early phase of 2 and early phase of 2ndnd stage stage of labor .of labor .

FLEXION FLEXION

When the head descent to the When the head descent to the narrow mid-cavity flexion should narrow mid-cavity flexion should occur.occur.

INTERNAL ROTATION .INTERNAL ROTATION .

The shape of the bony pelvis and The shape of the bony pelvis and direction of the pelvic floor muscles in direction of the pelvic floor muscles in addition to the well flexed head will addition to the well flexed head will help the head to rotate the head into help the head to rotate the head into the occipito anterior position .the occipito anterior position .

In a well flexed head the occiput will In a well flexed head the occiput will meet the pelvic floor and will guide meet the pelvic floor and will guide the direction of the rotation the direction of the rotation

EXTENSION.EXTENSION.

The head is deliver by extension The head is deliver by extension first the bregma ,face , and chin first the bregma ,face , and chin appear in succession over the appear in succession over the posterior vaginal opening and posterior vaginal opening and perineal body.perineal body.

RESTITUTION.RESTITUTION.

As soon as the head escape from As soon as the head escape from the vulva the head aligns itself the vulva the head aligns itself with the shoulderwith the shoulder

EXTERNAL ROTATION.EXTERNAL ROTATION.

In order to deliver the shoulders In order to deliver the shoulders have to rotate into the direct have to rotate into the direct anterior- posterior plane .anterior- posterior plane .

The doctor will rotate the head The doctor will rotate the head making the face of the fetus making the face of the fetus looking to medial aspect of the looking to medial aspect of the maternal thigh .maternal thigh .

Delivery of the shoulders .Delivery of the shoulders .

The anterior shoulder is under The anterior shoulder is under thethe

symphysis pubis and deliver symphysis pubis and deliver firstfirst

,and the posterior shoulder ,and the posterior shoulder deliverdeliver

subsequently subsequently

THIRD STAGE OF LABOR .THIRD STAGE OF LABOR .

Separation of the placentaSeparation of the placenta

occurs because of theoccurs because of the

reduction of the volume of reduction of the volume of thethe

uterus due to the uterineuterus due to the uterine

contraction and retraction contraction and retraction

THANK YOUTHANK YOU