Vertex Presentation
The vertex is the area of the vault bounded anteriorly by the anterior fontanelle and the coronal suture, posteriorly by the posterior fontanelle and the lambdoid suture and laterally by 2 lines passing through the parietal eminences.
In the vertex presentation the occiput typically is anterior and thus in an optimal position to negotiate the pelvic curve by extending the head. In an occiput posterior position, labor becomes prolonged and more operative interventions are deemed necessary. The prevalence of the persistent occiput posterior is given as 4.7 %
The vertex presentations are further classified according the position of the occiput, it being right, left, or transverse, and anterior or posterior:
- Left Occipito-Anterior (LOA), Left Occipito-Posterior (LOP), Left Occipito-Transverse (LOT);
- Right Occipito-Anterior (ROA), Right Occipito-Posterior (ROP), Right Occipito-Transverse (ROT);
The Occipito-Anterior position is ideal for birth - it means that the baby is lined up so as to fit through the pelvis as easily as possible. The baby is head down, facing the spine, with his back on one side of the front of the tummy. In this position, the baby's chin is tucked onto his chest, so that the smallest part of his head will be applied to the cervix first. The position is usually 'Left Occiput Anterior' or LOA - occasionally the baby may be Right Occiput Anterior or ROA.
Read more about this topic: Cephalic Presentation, Classification
Famous quotes containing the word presentation:
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—William Shakespeare (1564–1616)