Presentation (obstetrics)

In obstetrics, the presentation of a fetus about to be born specifies which anatomical part of the fetus is leading, that is, is closest to the pelvic inlet of the birth canal. According to the leading part, this is identified as a cephalic, breech, or shoulder presentation. A malpresentation is any presentation other than a vertex presentation.

Classification

Thus the various presentations are:

cephalic presentation :
* vertex —the most common and associated with the fewest complications
* sinciput
* brow
* face
* chin
breech presentation :
* complete breech
* footling breech
* frank breech
shoulder presentation:
*arm
*shoulder
*trunk
compound presentation—when any other part presents along with the fetal head

Related obstetrical terms

Attitude

Definition: Relationship of fetal head to spine:
*flexed,
*neutral,
*extended.
*hyperextended

Position

Relationship of presenting part to maternal pelvis based on presentation. The fetus enters the pelvis in the occipito-transverse plane, descent, and flexion and then rotates 90 degrees to the occipitoanterior.
* Cephalic presentation
** Vertex presentation with longitudinal lie:
***Left occipitoanterior —the occiput is close to the vagina, facing anteriorly and toward the left. This is the most common position and lie.
***Right occipitoanterior —the occiput faces anteriorly and toward the right. Less common than LOA, but not associated with labor complications.
***Left occipitoposterior —the occiput faces posteriorly and toward the left.
***Right occipitoposterior —the occiput faces posteriorly and toward the right.
***Occipitoanterior—the occiput faces anteriorly
***Occipitoposterior—the occiput faces posteriorly
** Face presentation
***Mentum anterior—the fetal chin is in the direction of the maternal pubic symphysis.
***Mentum posterior—the fetal chin is in the direction of the maternal sacrum. This presentation is not compatible with vaginal delivery.
*Breech presentation with longitudinal lie:
**Left sacrum anterior —the buttocks, as against the occiput of the vertex presentation, lie close to the vagina, which lie anteriorly and toward the left.
**Right sacrum anterior —the buttocks face anteriorly and toward the right.
**Left sacrum posterior —the buttocks face posteriorly and toward the left.
**Right sacrum posterior —the buttocks face posteriorly and toward the right.
**Sacrum anterior —the buttocks face anteriorly.
**Sacrum posterior —the buttocks face posteriorly.
* Shoulder presentations with transverse lie are classified into four types, based on the location of the scapula. This presentation needs to be delivered by cesarean section.
**Left scapula-anterior
**Right scapula-anterior
**Left scapula-posterior
**Right scapula-posterior

Lie

Definition: Relationship between the longitudinal axis of fetus and mother:
*longitudinal
*oblique
*transverse
**back up
**back down