Page 233 - Critical Maternity & Newborn Health Nursing

a. Good uterine contraction

b. Small size head

c. Wide pelvis

When the head meets resistance from the pelvic floor Correct

the deflexion (head becomes completely flexed) The Occiput

Rotates forward 3/8 of a circle and delivered as occipto-anterior

position.

2. Abnormal Mechanism (10 %): “According to the degree of

Deflexion”

1) Mild Deflexion(1%): Short anterior rotation: the occiput rotate

forwards 1/8 of a circle Deep transverse arrest

obstructed labor.

2) Moderate Deflexion (3%) The occiput and sinciput

meet the pelvic floor at the same time No rotation

occurs Persistent Occipto posterior Obstructed

labor

3) Marked deflexion (6%): the sinciput meets the pelvic floor first

and rotates forward 1/8 of a circle while the occiput rotates

backward Direct Occipto-posterior (DOP) or face

to pubis

Causes of Failure of Internal Rotation of the Head

1. Deflexion of the head is the most common cause.

2. Weak uterine contractions.

3. Contracted pelvis which mechanically interferes with rotation.

4. Drainage of liquor Amini due to rupture of the membrane.

232 Table of Contents