Brow Presentation

1.

Brow Presentation
Teacher; Kamilova Irina Kaharovna
By
Ramalingam Lokeswaran
Group;LA1-C-O-163(2)

2.

Brow is the rarest variety of cephalic presentation where the 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.

3.

CAUSES: The causes of persistent brow are more or less 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

4.

MECHANISM OF LABOR: Diameter of engagement is through the oblique
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

5.

MOLDING: Considerable overlapping of bones occurs if the labor lasts 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