From the Guidelines
To assess for molding of the fetal head in cases of suspected cephalopelvic disproportion (CPD), a careful vaginal examination during labor is crucial, focusing on the degree of overlap between the fetal skull bones, particularly the sagittal suture between the parietal bones, as indicated by 1. When evaluating molding, it's essential to consider the grading scale from 0 to 3, where grade 0 indicates bones are separated, grade 1 shows bones touching, grade 2 represents overlapping bones that can be reduced, and grade 3 indicates severe overlapping that cannot be reduced.
- Key factors to assess include:
- The degree of overlap between the fetal skull bones
- The presence of caput succedaneum (scalp swelling)
- The rate of descent despite adequate contractions
- Any arrest of labor
- The assessment should be performed during contractions and between contractions to evaluate progression, as suggested by 1.
- It's also important to document findings serially to track progression and identify any potential issues early on.
- While some degree of molding is normal during vaginal delivery, excessive molding with lack of descent indicates potential CPD that may require cesarean delivery to prevent fetal and maternal complications, highlighting the importance of thorough cephalopelvimetry to exclude the presence of disproportion, as noted in 1.
- Clinicians should be aware of other factors that signal concern, such as maternal diabetes and obesity, pelvic shape and size, fetal macrosomia, malposition (occiput posterior and transverse), malpresentation (brow), asynclitism, and excess molding, as discussed in 1.
- Differentiating between molding and true descent by means of serial suprapubic palpation of the base of the fetal skull is essential to ensure that descent is actually occurring, as emphasized in 1.