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Lesson 10: Fetal Positions and Adaptations
f.
Position. This is the relationship between a predetermined point of reference or direction on the presenting part of the fetus to the pelvis of the mother.(1) The maternal pelvis is divided into quadrants.
(a) Right and left side, viewed as the mother would.
(b) Anterior and posterior. This is a line cutting the pelvis in the middle from side to side. The top half is anterior and the bottom half is posterior.
(c) The quadrants never change, but sometimes it is confusing because the student or physician's viewpoint changes.
NOTE: Remember that when you are describing the quadrants, view them as the mother would.
O). This refers to the Y sutures on the top of the head.(2) Specific points on the fetus.
(a) Cephalic or head presentation.
1 Occiput (
2 Brow or fronto (
F). This refers to the diamond sutures or anterior fontanel on the head.3 Face or chin presentation (
M). This refers to the mentum or chin.(b) Breech or butt presentation.
S). This is the point of reference.1 Sacrum or coccyx (
2 Breech birth is associated with a higher perinatal mortality.
(c) Shoulder presentation.
Sc) or its upper tip, the acromion (A) would be used for the point of reference.1 This would be seen with a transverse lie.
2. Scapula (
(3) Coding of positions.
R for right, L for left).(a) Coding simplifies explaining the various positions.
1 The first letter of the code tells which side of the pelvis the fetus reference point is on (
2 The second letter tells what reference point on the fetus is being used (Occiput-
O, Fronto-F, Mentum-M, Breech-S, Shoulder-Sc or A).3 The last letter tells which half of the pelvis the reference point is in (anterior-
A, posterior-P, transverse or in the middle-T).
O.S.) or occiput at posterior (O.P.).(b) Each presenting part has the possibility of six positions. They are normally recognized for each position--using "occiput" as the reference point.
LOA).1 Left occiput anterior (
2 Left occiput posterior (
LOP).3 Left occiput transverse (
LOT).4 Right occiput anterior (
ROA).5. Right occiput posterior (
ROP).6 Right occiput transverse (
ROT).(c) A transverse position does not use a first letter and is not the same as a transverse lie or presentation.
1 Occiput at sacrum (
2 Occiput at pubis (
O.P.) or occiput at anterior (O.A.).(4) Types of breech presentations (see figure10-4).
(a) Complete or full breech. This involves flexion of the fetus legs. It looks like the fetus is sitting in a tailor fashion. The buttocks and feet appear at the vaginal opening almost simultaneously.
A--Complete. B--Frank. C--Incomplete.
Figure 10-4. Breech positions.
LOA and ROA positions are the most common and permit relatively easy delivery.(b) Frank and single breech. The fetus thighs are flexed on his abdomen. His legs are against his trunk and feet are in his face (foot-in-mouth posture). This is the most common and easiest breech presentation to deliver.
(c) Incomplete breech. The fetus feet or knees will appear first. His feet are labeled single or double footing, depending on whether 1 or 2 feet appear first.
(5) Observations about positions (see figure 10-5).
(a)
(b)
LOP and ROP positions usually indicate labor may be longer and harder, and the mother will experience severe backache.
Figure 10-5. Examples of fetal vertex presentations in relation to quadrant of maternal pelvis.
(c) Knowing positions will help you to identify where to look for FHT's.
R or L quad, above the umbilicus.1 Breech. This will be upper
2 Vertex. This will be lower
R or L quad, below the umbilicus.(d) An occiput in the posterior quadrant means that you will feel lumpy fetal parts, arms and legs (see figure 10-5 A). If delivered in that position, the infant will come out looking up.
(e) An occiput in the anterior quadrant means that you will feel a more smooth back (see figure 10-5 B). If delivered in that position, the infant will come out looking down at the floor.
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