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Obstetrics Simplified - Diaa M. EI-Mowafi

Brow Presentation

Definition

It is a cephalic presentation in which the head is midway between flexion and extension.

Incidence

About 1:1000 labour.

Aetiology

As face presentation.

Diagnosis

  • During pregnancy:
    • It is difficult.
    • The occiput and sinciput may be felt at the same level.
    • Ultrasonography and X-ray may be helpful.
  • During labour:
    • In addition to the previous findings, vaginal examination reveals the following features:
      • frontal bones,
      • supra-orbital ridges, and
      • root of the nose but not the chin.

Mechanism of Labour

  • Persistent brow:
    • The engagement diameter is the mento-vertical 13.5 cm which is longer than any diameter of the inlet so there is no mechanism of labour and labour is obstructed.
  • Transient brow:
    • may occur during conversion of vertex into face presentation. So if brow is flexed to become vertex or extended to become face it may be delivered.

Management

  • Early in the first stage:
    • Exclude contracted pelvis, if present do caesarean section.
    • The case is considered as transient brow, observed carefully and given a chance for spontaneous conversion into either face or vertex.
    • The rest of management as other malpresentation.
  • In the second stage:
    • The case is considered as persistent brow so:
      • Caesarean section is done if the foetus is living.
      • Craniotomy if the foetus is dead.

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