ATTITUDE OF THE FETAL HEAD

MEASUREMENT (1)

• Sagittal view of the cranium and upper spine.
• The attitude is measured by the angle formed between two lines:
• One line is drawn between the orbital ridge and occipital eminence.
• A second line drawn through the cervical and thoracic vertebrae.

FLEXION OF THE FETAL HEAD (1)

• An angle of less than 90°.

EXTENSION OF THE FETAL HEAD (1)

• An angle of above 90°.
• Mild extension (soldier position) = >90° to 120°.
• Moderate extension (star gazing fetus) = >120° to 150°.
• Severe extension = >150°.
• Hyperextension of the fetal head occurs in about 5% of breech presentation at or near term (2).
• Hyperextension is associated with considerable injury to the cervical spinal cord if vaginal delivery is attempted (3,4).
• Hyperextension is established as an indication for elective cesarean section (2,5).

REFERENCES

1. Rojansky N, Tanos V, Weinstein D. Sonographic evaluation of fetal head extension and maternal pelvis in cases of breech presentation. Acta Obstet Gynecol Scand 1994;73:607-611.
2. Caterini H, Langer A, Sama JC et.al. Fetal risk in hyperextension of the fetal head in breech presentation. Am J Obstet Gynecol 1975;123:632-636.
3. Abroms IF, Bresnan MJ, Zuckerman JE et.al. Cervical cord injuries secondary to hyperextension of the head in breech presentation. Obstet Gynecol 1973;41:369-378.
4. Bhagwanani SG, Price HV, Laurence KM et.al. Risks and prevention of cervical cord injury in the management of breech presentation and hyperextension of the fetal head. Am J Obstet Gynecol 1973;115:1159-1161.
5. Ballas S, Toaff R. Hyperextension of the fetal head in breech presentation: radiological evaluation and significance. Br J Obstet Gynecol 1976;83:201-204.