UNUSUAL PRESENTATIONS AND POSITIONS
=Breech Presentation.=—The pelvic pole enters the inlet first, once in
thirty cases and more commonly in primiparas than otherwise.
_Etiology._—Anything that interferes with or deranges the laws of normal
gestation will predispose to, or produce this anomaly.
Thus, if the head is too large, as in hydrocephalous, or if the fœtus is
too movable, as in hydramnios, or if an obstacle, like placenta previa,
contracted pelvis or tumors prevent the proper approach of the head to
the inlet, the mechanism will be disturbed and a breech or possibly a
shoulder presentation will result.
Abnormal flaccidity of the uterine or abdominal walls, prematurity or
twins also contribute definitely to its occurrence.
_The attitude_ of the child generally retains its normal aspect of
complete flexion. This pose, however, is not maintained invariably for
on occasion the buttocks and genitals may rest upon the inlet while one
or both feet may be extended on the thighs and lie beside the neck, or
the thighs may be extended while the knees remain flexed, and what is
known as a knee presentation, or if the foot comes down, a footling
presentation results.
_Positions._—The sacrum is the most prominent bony landmark of the
breech, hence the positions are named from the relation this bone bears
to the four quadrants of the inlet.
[Illustration: Fig. 61.—The breech. Left-sacro-anterior position.
(Lenoir and Tarnier.)]
We have therefore in their order of frequency the following
designations: Left-sacro-anterior, where the sacrum lies to the left of
the median line of the mother’s body and in front; right-sacro-anterior,
where the sacrum lies to the right and in front; right-sacro-posterior,
where the bone lies near the mother’s vertebral column, and on the right
side; and the left-sacro-posterior position, where the bone occupies a
corresponding place on the left side.
_Diagnosis._—The recognition of this presentation is most easily secured
by external abdominal palpation in pregnancy, which may be reinforced
during labor by the internal examination.
[Illustration: Fig. 62.—The breech. Left-sacro-posterior position.
(Lenoir and Tarnier.)]
Externally the palpating fingers at the pelvic brim will note the
absence of the hard, round head, and feel a mass, softer, quite
irregular in shape, and less defined than customary. Movements also may
be appreciated that would be too far down in the uterus if the head was
presenting.
Next the hard, spherical tumor of the head can be outlined somewhere in
the fundus, and the heart tones, instead of being below the umbilicus
will be on the same level or even higher.
Vaginally the cervix is not filled out, the presenting part does not
come down, but after labor has begun the distinctive features of the
breech gradually become more evident, as they are driven into the
pelvis.
One or both feet, or the buttocks, may be recognized. The examining
finger may possibly enter the anus and be stained with meconium or
pinched by the sphincter, which differentiates this orifice from the
mouth.
One after another the characteristic landmarks appear until the
diagnosis can not be doubtful. As soon as the sacrum is found or the
legs definitely placed, the position can be named.
_Mechanism._—The hips always enter the inlet in one of the oblique
diameters and the back is turned to the same part of the uterine wall as
in the corresponding vertex positions.
The acts described in the mechanism for vertex deliveries show a
somewhat different order. Descent is first, then comes internal anterior
rotation, which brings the anterior hip under the symphysis and its
delivery is quickly followed by the posterior hip, which rolls out over
the perineum.
The body advances, as a rule, with the back toward the front of the
mother. The shoulders with arms folded move under the pubic arch and
then the head delivers in a state of flexion. The head, of course, has
no caput and it is not moulded.
This mechanism may be greatly impeded or complicated at any stage of the
movement. The advance may be retarded to a pathological degree, the
belly may be large and as it passes along the canal one or both arms may
be stripped up alongside the head or even into the back of the neck. The
head may be arrested at the inlet by the arms, by its degree of
deflexion, or by pelvic contraction.
The rotation may not take place, or it may be abnormal, and the belly of
the child look forward toward the mother’s. Any of these variations adds
further to the difficulty of the labor and to the danger of the partners
in the event.
Artificial aid may be required which brings with it the possibility of
sepsis.
The fœtal mortality which averages five per cent is due mostly to
asphyxiation. Interference with the supply of oxygen begins as soon as
the cord passes the vulva and the child must be delivered in eight
minutes from that time, or perish. Partial detachment of the placenta
may also cut off the oxygen to a fatal degree, and the child may be
unable to breathe when born on account of mucus sucked into the trachea
by premature efforts at respiration.
Minor accidents also occur, such as fractures, dislocations, and
paralysis from injury to the nerve trunks.
_Management._—In the interest of the child, this presentation is
occasionally converted into a vertex by external version during the last
weeks of pregnancy or in labor before the membranes have ruptured. It is
difficult, however, to maintain the vertex over the inlet. The woman
must be kept quiet in a horizontal posture and long roller splints
applied to the side of the child in utero and bound on.
In primiparas, this is nearly impossible, and it is wiser, in the
absence of some great necessity to warn the parents of the conditions
and dangers and let them share in the responsibility.
[Illustration: Fig. 63.—Extraction of the breech. Traction on one leg.
(Hammerschlag.)]
When the labor begins, the bag of waters must be kept from rupture as
long as possible and when it finally breaks, an internal examination
should be made to see if the cord has come down. If this happens it may
be necessary to expedite the delivery by external assistance.
[Illustration: Fig. 64.—Breech delivery. Extraction of the trunk by
pulling on the hips. (Hammerschlag.)]
The doctor brings down a foot, if it is not already down, or pulls on
the breech until the feet drop out. Compression of the cord must be
always in mind. It is always compressed after the umbilicus has passed
the navel. The shoulders are delivered by seizing the feet with the
operating hand and swinging the body out of the way. This brings the
posterior shoulder, which should be first, into the hollow of the
pelvis. Extraction is then completed by what is called the Smellie-Veit
maneuver. The child is put astride one arm, the first finger of which is
hooked into the child’s mouth to maintain flexion. The fingers of the
other hand then grasp the shoulders of the child astride the back of the
neck and traction is made downward in the axis of the inlet until the
head slips into the excavation.
[Illustration: Fig. 65.—Breech delivery. Delivering the shoulder. The
body is swung strongly upward and outward to bring posterior shoulder
into the pelvis. (Hammerschlag.)]
[Illustration: Fig. 66.—The delivery of the after-coming head by the
Smellie-Veit maneuver. (Hammerschlag.)]
If the head is delayed at the inlet, it may be necessary to put the
woman in the Walcher position (q. v.) and for the nurse to use the
Wiegand compression (q. v.). The feet _must not_ be fastened in stirrups
for breech cases.
[Illustration: Fig. 67.—Shoulder presentation. Left-scapulo-anterior
position. (Lenoir and Tarnier.)]
Forceps are _not_ recommended for application to the breech as they do
not fit and are liable to slip off and injure both child and mother. The
fingers are best.
Forceps are _not_ recommended for the after-coming head unless the child
is dead. If the child lives, the Smellie-Veit is more-successful; and if
the child dies, the cranioclast, if possible, will save the mother much
suffering and avoid some injury to the tissues.
=Transverse or Shoulder Presentations.=—These are cases in which the
long axis of the child lies directly across or obliquely across the long
axis of the uterus.
The shoulder (scapula) is the bony landmark, and the part which most
frequently impends over the inlet. This presentation probably occurs
once in two hundred labors.
It is due to the same conditions that were given for breech cases;
namely, weak abdominal or uterine muscles, pelvic contraction, placenta
previa, hydramnios, and twins.
It is easily recognized in pregnancy, and must not be neglected, for it
is impossible of delivery without first changing it into a longitudinal
presentation. If this correction is not done, rupture of the uterus is
liable to occur, with the consequent death of both mother and child.
The _treatment_ is invariably version.
=Face and Brow Presentations.=—The face presents once in about three
hundred labors. In this case, the head is completely extended so that
the occiput rests against the back of the neck. The trunk and spine are
straightened out while the legs and arms remain in the normal attitude
of flexion.
The causes of these anomalies must be sought in those conditions which
bring about the deflexion of the chin. The most common are pelvic
contraction, large child, placenta previa, hydramnios, goiter,
anencephalus and multiparity.
[Illustration: Fig. 68.—Face presentation. (Bumm.)]
Face positions take their names from the location of the chin
(mentum—Latin). Thus the most frequent face position is the
right-mento-posterior.
The diagnosis is not easy and may not be conclusive until the bony
prominences of the face, such as the nose and orbital ridges can be
distinguished by vaginal examination.
[Illustration: Fig. 69.—Descent of the chin in face presentation.
(Bumm.)]
The delivery is protracted from three to five hours beyond the average
by this complication, and the mortality is higher both for mother and
child. The face is badly swollen and disfigured, but the normal
condition of the tissues will be restored by the end of a week. Most
face cases terminate spontaneously, but operative interference is not
infrequent on account of danger to mother or child.
Version or manual correction of the presentation may be done before
engagement.
Forceps is the operation of choice after the head is fixed in the
pelvis, but it may be necessary to precede the delivery by a preparatory
pubiotomy, or in case of failure, to do a craniotomy on the dead child.
If the chin does not rotate forward under the symphysis, the labor is
impossible without pubiotomy or the destruction of the child. In
general, the case should be left to nature unless some definite
indication to interfere develops.
[Illustration: Fig. 70.—Delivery in face presentation. (Bumm.)]
The brow presents much more rarely than the face, possibly once in a
thousand labors. It is due to the same conditions as bring about the
presentation of the face. The mortality for both mother and child is
higher than in face cases. The whole labor is harder and longer, besides
being more dangerous to life and to tissues.
This presentation, if recognized before the head is fixed, should be
converted into a breech by version, but after the head comes down, it
may be possible by hand or forceps to deliver either as a face or as an
occipito-posterior, but otherwise the cranioclast must be considered.
=Occipito-posterior position= is the name given to vertex cases wherein
the occiput lies in one or the other of the two posterior quadrants of
the pelvic inlet.
These labors are necessarily prolonged, both in the first and second
stages, because the mechanism of delivery is deranged by the larger
diameters brought into relation with the bony canal and by the
ineffectiveness of the contractions.
The pains in the second stage may become violent and extremely painful,
but the labor does not advance appreciably. After a little experience,
mere observation of the course of the labor will cause the suspicion to
arise in the mind of a competent nurse that the occiput is posterior.
The diagnosis will be cleared up by the doctor’s internal examination,
which shows the large fontanelle anterior and the sagittal suture
running backward.
The head is partially deflexed and it may not be possible at first to
find the small fontanelle.
The position terminates by delivery uncorrected, by spontaneous rotation
into an anterior position, or is corrected by the doctor.
Correction should not be attempted until it is apparent that the anomaly
will not right itself, which it will do in four cases out of five.