Specific points on the fetus.
(a) Cephalic or head presentation.
1 Occiput (O). This refers to the Y sutures on the top of the head.
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
Breech or butt presentation.
1 Sacrum or coccyx (S). This is the point of reference.
2 Breech birth is associated with a higher perinatal mortality.
1 This would be seen with a transverse lie.
2. Scapula (Sc) or its upper tip, the acromion (A) would be used
for the point of reference.
Coding of positions.
(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 (R for right, L for left).
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).
(b) Each presenting part has the possibility of six positions. They are
normally recognized for each position--using "occiput" as the reference point.
1 Left occiput anterior (LOA).
2 Left occiput posterior (LOP).
3 Left occiput transverse (LOT).