page_title: Cephalic presentation
section_title: Vertex presentation
hierarchical_section_title: Cephalic presentation / Classification / Vertex presentation
caption_attribution_description: English: The left occipito-anterior variant of cephalic presentation
context_page_description: A cephalic presentation or head presentation or head-first presentation is a situation at childbirth where the fetus is in a longitudinal lie and the head enters the pelvis first; the most common form of cephalic presentation is the vertex presentation where the occiput is the leading part. All other presentations are abnormal which are either more difficult to deliver or not deliverable by natural means.
context_section_description: 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 to the position of the occiput, both 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 its back anterior. In this position, the baby's chin is tucked onto its chest, so that the smallest part of its 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.
caption: Right occipito-transverse
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