7.10 Brow presentation

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    Brow presentation constitutes an absolute foeto-pelvic disproportion, and vaginal delivery is impossible (except with preterm birth or extremely low birth weight).

     

    This is an obstetric emergency, because labour is obstructed and there is a risk of uterine rupture and foetal distress.

    7.10.1 Diagnosis

    • Head is high; as with a face presentation, there is a cleft between the head and back, but it is less marked.
    • On vaginal examination the brow, orbits, anterior fontanelle and, occasionally, the eyes and bridge of the nose are palpable (Figures 7.9). But it is not possible to palpate:
      • the chin (it is not a face presentation),
      • the posterior fontanelle (it is not a vertex presentation).

     

    Figures 7.9 - Brow presentation

     

    Figure 7-9

     

    Any mobile presenting part can subsequently flex. The diagnosis of brow presentation is, therefore, not made until after the membranes have ruptured and the head has begun to engage in a fixed presentation. Some brow presentations will spontaneously convert to a vertex or, more rarely, a face presentation.

     

    During delivery, the presenting part is slow to descend: the brow is becoming impacted.

    7.10.2 Management

    Foetus alive

    • Perform a caesarean section. When performing the caesarean section, an assistant must be ready to free the head by pushing it upward with a hand in the vagina.
    • As a last resort, if caesarean section is impossible, attempt two manoeuvres:
      • Convert the brow presentation to a face presentation: between contractions, insert the fingers through the cervix and move the head, encouraging extension (Figures 7.10).
      • Attempt internal podalic version (Section 7.9).

    Both these manoeuvres pose a significant risk of uterine rupture. Vacuum extraction, forceps and symphysiotomy are contra-indicated.

     

    Figures 7.10 - Manoeuvre to convert brow to face presentation

     

    Foetus dead

    Perform an embryotomy if the cervix is sufficiently dilated (Chapter 9, Section 9.7) otherwise, a caesarean section.