Fetal Malpresentation

FETAL MALPRESENTATIO

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by: LAYRE V. TALENTO

Flexion-As descent occurs and the fetal head reaches the pelvic floor, the head bends forward onto the chest, making the smallest anteroposterior diameter (the suboccipitobregmatic diameter) present to the birth canal. Flexion is also aided by abdominal muscle contraction during pushing.

Extension- As the occiput is born,

the back of the neck stops beneath the pubic arch and acts as a pivot for the rest of the head. The head extends, and the foremost parts of the head,

the face and chin, are born.

Two other factors play a part in whether a fetus is lined up in the best position to be born: fetal presentation and position

Attitude- describes the degree of

flexion a fetus assumes during labor or the relation of the fetal parts to each other.

A fetus in good attitude is in complete flexion: the spinal column is bowed forward, the head is flexed forward so much that the chin touches the sternum, the arms are flexed and folded on the chest, the thighs are flexed onto the abdomen, and the calves are pressed against the posterior aspect of the thighs.

This normal “fetal position”is advantageous for birth because it helps a fetus present the smallest anteroposterior diameter of the skull to the pelvis and also because it puts the whole body into an ovoid shape, occupying the smallest space possible.

A fetus is in moderate flexion if the chin is not touching the chest but is in an alert or “military position” . This position causes the next-widest anteroposterior diameter, the occipital frontal diameter, to present to the birth canal. A fair number of fetuses assume a military position during the early part of labor. This does not usually interfere with labor, because later mechanisms of labor (descent and flexion) force the fetal head to fully flex.

A fetus in partial extension presents the “brow” of the head to the birth canal.

If a fetus is in complete extension, the back is arched, and the neck is extended, presenting the occipitomental diameter of the head to the birth canal, a face presentation.

This unusual position presents too wide a skull diameter to the birth canal for normal birth.

Such a position may occur if there is less than the normal amount of amniotic fluid present (oligohydramnios), which does not allow a fetus adequate movement.

It also may reflect a neurologic abnormality in thefetus causing spasticity.

Fetal Lie - is the relationship

between the long (cephalocaudal)

axis of the fetal body and the long (cephalocaudal) axis of a woman’s body; in other words, whether the fetus is

lying in a horizontal (transverse) or a vertical (longitudinal)

position.

Longitudinal lies are further classified as cephalic, which means the head will be the first part to contact the

cervix, or breech, with the breech, or buttocks, as the first portion to contact the cervix.

Fetal presentation denotes the body part that will first contact the cervix or be born first. This is determined by a combination of fetal lie and the degree of fetal flexion (attitude).

TYPES OF FETAL PRESENTATION

TYPES OF FETAL PRESENTATION

Cephalic PresentationBreech PresentationShoulder Presentation

CEPHALIC PRESENTATIONA cephalic presentation is the most frequent type of presentation

With this type of presentation, the fetal

head is the body part that will first contact the cervix.

The four types of cephalic presentation (vertex, brow, face, and mentum)

BREECH PRESENTATIONA breech presentation means that either the buttocks or the feet are the first body parts that will contact the cervix.

A good attitude brings the fetal knees up against the fetal abdomen; a poor attitude means that the knees are extended.

BREECH PRESENTATIONBreech presentations can be difficult births, with the presenting

point influencing the degree of difficulty.

Three types of breech presentation (complete, frank, and footling) are possible.

CAUSESUterine relaxation due to multiparity

Fetal abnormalities – hydrocepahlus, anencephalus

Hydramnios and oligohydrmanios

Congenital abnormalities of the uterus – bicornuate uterus

Contracted pelvis

CAUSESPrevious breech deliverySpace occupying mass in the uterus that prevents the head from fitting into the lower portion such as placenta previa and fibroids

PrematurityMultiple pregnancy

SHOULDER PRESENTATIONIn a transverse lie, a fetus lies horizontally in the pelvis so that the longest fetal axis is perpendicular to that of the mother.

The presenting part is usually one of the shoulders (acromion process), an iliac crest, a hand, or an elbow.

CAUSESLax uterine and abdominal muscles due to multiparity is most common cause

Contacted pelvisFibroids and congenital abnormality of the uterus

Preterm fetus, hydrocephalusPlacenta previaMultiple pregnancy

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