Face presentation

Etiology and diagnostics

Most often, the pathology develops directly during labor when a brow presentation transitions into the extreme (third) degree of extension. During pregnancy, this condition occurs rarely. The main causes during this period include fetal neck tumors or multiple nuchal cord entanglement, which mechanically impede normal flexion.

A combination of methods is used to establish an accurate diagnosis:

• External obstetric examination: during the fourth maneuver, a pronounced depression is palpated between the fetal occiput and back, while the sharp protruding part—the chin—is clearly defined on the opposite side.
• Auscultation: unlike flexed presentations, fetal heart tones are most clearly auscultated on the side of the fetal thorax.
• Ultrasound: allows visual confirmation of maximum head extension.
• Vaginal examination: performed when the cervix is dilated by 2–3 cm. The obstetrician identifies the chin, mouth, nose, and supraorbital ridges.

Important rule: the internal examination must be extremely careful to avoid injuring the fetal eyes. Differential diagnosis with complete breech presentation is mandatory, as an inexperienced physician may mistake the anus for the mouth, and the coccyx and ischial tuberosities for facial bones.

Biomechanism of labor

Face presentation is considered the most favorable of all extension varieties, as the head passes through the pelvic planes with its smallest dimension—the vertical diameter (9.5 cm). Nevertheless, the biomechanism has strict frameworks.

1. First movement — maximum head extension. The process occurs in the plane of the pelvic inlet. The chin lowers and becomes the leading point. The facial line (the conventional axis passing through the frontal suture and nose) sets in one of the oblique diameters or the transverse diameter of the pelvis.
2. Second movement — internal rotation of the head. Rotation begins during the transition to the wide part of the pelvic cavity and ends at the outlet. A posterior position is formed: the chin turns anteriorly (toward the mother's anterior abdominal wall), and the occiput is placed in the sacral concavity. Critically important: delivery via the natural birth canal is possible exclusively in the posterior position!
3. Third movement — head flexion. A fixation point is formed under the lower edge of the symphysis—the hyoid bone. The head performs flexion: first, the edematous lips and chin emerge from the vulvar cleft, and then the occipital part is born.
4. Fourth movement — internal rotation of the shoulders and external rotation of the head. Proceeds in the same manner as in other cephalic presentations.

Course and management of labor

Due to the absence of an internal girdle of contact, labor is often complicated by premature rupture of membranes. The birth act itself becomes protracted because the process of maximum head extension requires more time and effort from the parturient woman than standard flexion in occiput presentation.

The risk of perineal tears increases significantly for the mother. This is due to the fact that the head crowns with a larger diameter, and the fetal occipital part is incapable of configuration under such conditions.

Obstetric tactics With average fetal dimensions and normal dimensions of the maternal pelvis, labor usually ends favorably. Doctors adhere to a strict expectant management approach with continuous monitoring of the character of uterine activity and fetal heartbeat. In the first stage of labor, it is necessary to carefully monitor the preservation of the posterior position.

Indications for emergency cesarean section (CS):

• Transition to the anterior face presentation (vaginal delivery is impossible).
• Appearance of signs of cephalopelvic disproportion (delay leads to uterine rupture).
• Prolapse of the umbilical cord loops.
• Acute fetal hypoxia.
• Uterine inertia.

Appearance of the newborn

Since the face is the presenting part, it undergoes severe pressure from the mother's birth canal. This leads to the formation of a specific caput succedaneum.

Upon examination of the newborn, the neonatologist notes:

• Pronounced edema of the facial soft tissues (especially eyelids, lips, and nose).
• Hyperemia and cyanosis of the facial skin, which is a direct consequence of venous stasis during labor.

Briefly: answers to topical questions

Class and exam questions

What else to study on this topic

• Differential diagnosis of face and breech presentations during vaginal examination
• Features of the biomechanism of labor in brow presentation
• Causes and prevention of premature rupture of membranes
• Signs of the formation of cephalopelvic disproportion in labor
• Technique for performing the fourth maneuver of external obstetric examination

Other topics in the "Obstetrics" section

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