Brow Presentation

presenting partis the brow and the attitude of the head

is short that of degree of extension necessary to produce face presentation, i.e. the head lies in between full flexion and full extension. The denominator is the fore head

INCIDENCE: The incidence of brow is very rare, about 1 in 1,000 births. However, it may persist temporarily while a deflexed head tends to become extended to produce a face presentation. This happens especially in flat pelvis where the biparietal diameter is held in the sacrocotyloid diameter.

the same as those of face presentation. The position is

commonly unstable and converts to either vertex or face presentation

DIAGNOSIS: Antenatal diagnosis is rarely made. The findings are more or less like those of face presentation

Vaginal examination: The position is to be confirmed on vaginal examination by palpating supraorbital ridges and anterior fontanel. If the anterior fontanel is on mother’s left, with the sagittal suture in transverse pelvic diameter, it is left frontum transverse position. In late labor, the landmarks may be obscured by caput formation

Sonography is confirmatory and also helps in excluding bony congenital malformation of the fetus

diameter with the brow anterior or posterior. As the engaging

diameter of the head is mentovertical (14 cm), there is no mechanism of labor in an average size baby with normal pelvis. However, if the baby is small and the pelvis is roomy with good uterine contractions, delivery can occur in mentoanterior brow position. The brow descends until it touches the pelvic floor.

Internal rotation and descent occur till the root of the nose hinges under the symphysis pubis. The brow and the vertex are delivered by flexion followed by extension to deliver the face. The mechanism is more or less the same as face-to-pubis delivery. Usual restitution and external rotation occur. There is no mechanism in posterior brow position

TRIAL OF LABOR: Brow presentation when transitory, trial of labor may be permissible. Correction of brow with felexion to occiput presentation or complete extension to a face presentation occurs. In such a situation, though rare, trial of labor may be possible

long. There is compression of submentovertical diameter with elongation of

occipitofrontal diameter . There is associated marked bulging of the forehead due to caput formation.

MANAGEMENT During pregnancy: If the presentation is diagnosed during pregnancy and there is no other contraindications for vaginal delivery, nothing is to be done. Contracted pelvis and congenital malformation of the fetus are to be excluded. Spontaneous correction into face is likely to occur. Elective cesarean section: Cases with persistent brow presentation are delivered by elective cesarean section. During labor: (1) In uncomplicated cases, if spontaneous correction to either vertex or face fails to occur early in labor, cesarean section is the best method of treatment. (2) Manual Correction to face with full dilatation of cervix is seldom practiced nowadays. (3) Craniotomy—If the labor becomes obstructed and the baby is dead, craniotomy is done. Rupture of the uterus should be excluded