Obstetrical Terminologies

Obstetrical Terminologies refer to the specific terms used to describe fetal orientation during parturition in animals.

There are three obstetrical terminologies:

1. Presentation (P₁)
2. Position (P₂)
3. Posture (P₃)

1. Presentation (P₁)

The relationship between the spinal axis of the fetus and that of the dam determines the presentation. (1) Presentations can be either longitudinal or transverse. (2) The portion of the fetus approaching or entering the pelvic cavity or birth canal varies based on the presentation. In a longitudinal presentation, this portion is either anterior or posterior, whereas in a transverse presentation, it is either dorsal or ventral.

2. Position (P₂)

Position refers to the relationship of the fetus’s dorsum in a longitudinal presentation or its head in a transverse presentation to the quadrants of the maternal pelvis. These quadrants include the sacrum, right ilium, left ilium, and pubis.

3. Posture (P₃)

Posture refers to the relationship of the fetus’s extremities—such as the head, neck, and limbs—to its own body. The extremities may be flexed, extended, or retained beneath, to the right or left side, or above the fetus.

In uniparous animals, the normal presentation is the anterior longitudinal presentation in a dorsosacral position, with the head resting on the metacarpal bones and the knees of the extended forelimbs. Birth can occur without assistance if the fetus is in the posterior longitudinal presentation, dorso-sacral position, with its hind limbs extended.