Feto-Pelvic Relationship

Subject: Midwifery I (Theory)

Overview

the phrase used to describe the connection between the mother's pelvis and the fetus in pregnancy. While examining the pregnant uterus, the midwife must be knowledgeable with a variety of terms. The outcome will influence whether the baby is delivered normally or abnormally, making it crucial. The term "lie" describes the connection between the mother's and the fetus' long axes. The attitude of the fetus refers to how the various sections of the embryo relate to one another. The fundamental stances are ones of flexion and extension. Presentation describes the area of the fetus that is located at the lower pole of the uterus or at the brim of the pelvis.The term "denominator" describes an arbitrary location selected for each fetal component to characterize its position in relation to the various quadrants of the maternal pelvis. The denominator's relationship to the front, rear, or sides of the maternal pelvis is referred to as position. The pelvis is divided into equal segments at a 45-degree angle for descriptive purposes, with the denominator located in each segment. When the broadest presenting transverse diameter has gone past the brim of the pelvis, engagement is said to have taken place. The presenting part's position with relation to the mother's pelvis is referred to as station.

Feto-Pelvic Relationship

the phrase used to describe the connection between the maternal pelvis and the fetus in pregnancy. While inspecting the pregnant uterus, the midwife must be conversant with a different phrase that is employed. The outcome will influence whether the baby is delivered normally or abnormally, making it crucial.

  • Lie

    • This denotes the relationship between the long axis of the fetus and the long axis of the mother. The lie of the fetus may be :
    • Longitudinal lie or vertical:
      • When the long axis of the fetus corresponds to the long axis of the mother. The commonest lie is longitudinal (99.5%) e.g. vertex presentation, breech presentation.
    • Transverse lie:
      • When the long axis of the fetus is perpendicular to the long axis of the mother. It is called transverse.
    • Oblique lie:
      • When the fetal long axis crosses the maternal long axis obliquely at an angle other than a right angle.

  • Attitude:

    • The attitude of the fetus refers to how the various sections of the embryo relate to one another. The fundamental stances are ones of flexion and extension. In utero, the typical fetal posture is one of flexion, with the head bowed, the chin tucked in, the arms and legs folded in front of the body, and the back arched. There may be exceptions to this general attitude, and the legs may extend in the breech position or the head may extend (with a deflexed vertex, brow, or face presentation depending on the degree of extension). In such cases, the path of work may be changed appropriately.

  • Presentation:

    • Presentation refers to the part of the fetus which lies at the pelvic brim or in the lower pole of the uterus. There are five presentations. Vertex, face, and brow are all head or cephalic presentation when the head is flexed vertex will present; when it is fully extended the face presents and when partially extended the brow presents. The approximate incidence of each presentation is given below:
      • Vertex: 96.8%
      • Breech: 2.5%
      • Shoulder: 0.5%
      • Face: 0.2%
      • Brow: 0.1%

  • The Presenting Part:

    • The presenting part is defined as the part of the presentation which overlies the internal os and is felt by the examining finger through the cervical opening. Thus is a cephalic presentation, the presenting part may be vertex (commonest), brow or face, depending upon a degree of flexion of the head.

  • Denominator:

    • This term refers to an arbitrary point chosen for each fetal presenting part to describe its position with reference to the different quadrants of maternal pelvis. The following are the denominator of a different presentation.

  • Presentation Denominator

    • Vertex occiput
    • Face mentum or chin
    • Breech sacrum
    • Shoulder scapula

  • Position:

    • It is the relation of the denominator to the front, back or sides of the maternal pelvis. For descriptive purpose, the pelvis is divided into equal segments of 45 degrees to place the denominator in each segment. The various position in vertex presentation could be described as a left occiput anterior (LOA), left occiputo lateral (LOL), Left occiputo posterior (LOP), right occipital anterior (ROA), right occipito lateral (ROL), and right occipital posterior (ROP). The commonest position is left occipito anterior, which is also known as first vertex position. But during the onset of labor, the commonest position is left occipito lateral.

  • Engagement:

    • When the broadest presenting transverse diameter has gone past the brim of the pelvis, engagement is said to have taken place. This is the bitrochanteric diameter in a breech presentation and the biparietal diameter in a cephalic presentation. Engagement is a crucial indicator that a vaginal delivery may be anticipated and that the mother's pelvis is likely to be suitable for the size of the specific fetus.
    • Head engagement occurs between 36 and 38 weeks of pregnancy in primigravidae, and during labor in multigravidae.

  • Station:

    • A station is the relationship of the presenting part to the mother’s pelvis.
    • Relationship to the pelvic brim during antenatal period –free or engaged.
    • Relationship to the ischial spine during labor.
    • Above ischial spines – high cavity
    • At ischial spines – mid cavity
    • Below ischial spines - low cavity

It can also be assessed by indicating ‘0’ for ischial spine, if the head is above the spine, the station is (-) negative and if the presenting part is below, the station is (+) positive.

 Reference

GFMER. 22 September 2016 http://www.gfmer.ch/Obstetrics_simplified/foetal_skull.htm

Nursing Crib. 11 November 2010. http://nursingcrib.com/anatomy-and-physiology/the-fetal-skull/

Quizlet. https://quizlet.com/8585093/pelvis-the-fetal-skull-105-flash-cards

Sweet, B.r., 1989, maye’s midwifery, A textbook for midwives; 11th edition, Bailliere Tindall, London, Philadelphia

Tuitui R. 2002, A textbook of Midwifery A (Antenatal), 3rd edition, Vidyarthi Pustak Bhandari (Publisher and Distributor), Bhotahity, Kathmandu

 

 

 
Things to remember
  • The term used to describe the relationship between the fetus in utero and the maternal pelvis.
  • There are a different term used in which the midwife must familiar while examine the pregnant uterus. It is important because it determines whether the baby will be delivered normally or abnormally.
  • Lie denotes the relationship between the long axis of the fetus and the long axis of the mother.
  • The relation of the different parts of the fetus to one another is called an attitude of the fetus. The basic attitude is those of flexion and extension.
  • Presentation refers to the part of the fetus which lies at the pelvic brim or in the lower pole of the uterus.
  • The presenting part is defined as the part of the presentation which overlies the internal os and is felt by the examining finger through the cervical opening.
  • Denominator  refers to an arbitrary point chosen for each fetal presenting part to describe its position with reference to the different quadrants of maternal pelvis.
  • Position is the relation of the denominator to the front, back or sides of the maternal pelvis. For descriptive purpose, the pelvis is divided into equal segments of 45 degrees to place the denominator in each segment.
  • Engagement is said to have occurred when the widest presenting transverse diameter has passed through the brim of the pelvis.
  • Station is the relationship of the presenting part to the mother’s pelvis.
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Fetopelvic Relationships
Questions and Answers

The phrase used to describe the connection between the mother's pelvis and the fetus in utero. While inspecting the pregnant uterus, the midwife must be familiar with a different term that is used. The outcome will determine whether the baby is delivered normally or abnormally, making it crucial.

Lie:  

This indicates how the mother's long axis and the fetus' long axis are related. The fetus may be telling a lie if:

  • Longitudinal lie or vertical: When the mother's long axis and the fetus' long axis line up. The most frequent lie (99.5%), like as vertex presentation and breech presentation, is longitudinal.
  • Transverse lie: When the mother's long axis and the fetus' long axis are perpendicular to each other. It's known as transverse.
  • Oblique lie: When there is an angle other than a right angle where the fetal long axis crosses the maternal long axis.

Attitude:

The attitude of the fetus refers to how the various sections of the embryo relate to one another. The fundamental stances are ones of flexion and extension. In utero, the typical fetal posture is one of flexion, with the head bowed, the chin tucked in, the arms and legs folded in front of the body, and the back arched. There may be exceptions to this general attitude, and the legs may extend in the breech position or the head may extend (with a deflexed vertex, brow, or face presentation depending on the degree of extension). In such cases, the course of work may be changed appropriately.

Presentation:

Presentation describes the area of the fetus that is located in the lower pole of the uterus or at the brim of the pelvis. Five presentations are made. Below is a list of the approximate incidence of each presentation:

  • Vertex: 96.8%
  • Breech: 2.5%
  • Shoulder: 0.5%
  • Face: 0.2%
  • Brow: 0.1%

When the head is flexed, the vertex will present; when it is fully extended, the face will present; and when it is only slightly extended, the brow will present. These are all examples of head or cephalic presentation.

The Presenting Part:

The portion of the presentation that covers the internal os and can be felt by the examining finger through the cervical opening is referred to as the presenting part. This is a cephalic presentation, and depending on the degree of head flexion, the presenting part may be the vertex (commonest), brow, or face.

Denominator:

This phrase refers to an arbitrary point selected for each fetal component to indicate its position in relation to the various quadrants of the mother's pelvis. The common factor in a different presentation is the list below.

Presentation Denominator:

  • Vertex occiput
  • Face mentum or chin
  • Breech sacrum
  • Shoulder scapula

Position:

It refers to how the denominator is related to the sides, back, or front of the uterus. The pelvis is divided into equal segments at a 45-degree angle for descriptive purposes, with the denominator located in each segment. Left occiput anterior (LOA), left occiputo lateral (LOL), left occiputo posterior (LOP), right occipital anterior (ROA), right occipito lateral (ROL), and right occipital posterior could be used to describe the various positions in vertex presentation. Left occipito anterior, sometimes referred to the first vertex position, is the most prevalent position. But when labor starts, the left occipito lateral position is most frequently used.

Engagement:

When the broadest presenting transverse diameter has gone past the brim of the pelvis, engagement is said to have taken place. This is the bitrochanteric diameter in a breech presentation and the biparietal diameter in a cephalic presentation. Engagement is a crucial indicator that a vaginal delivery may be anticipated and that the mother's pelvis is likely to be adequate for the size of the specific fetus.

Head engagement occurs between 36 and 38 weeks of pregnancy in primigravidae, and during labor in multigravidae.

Station:

The position of the presenting portion relative to the mother's pelvis is known as a station.

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