point of the spinous ligament passing from the last lumbar verte-
bra to the sacrum, in seventeen iDelves, taking them indifferently, well
formed and distorted. The following are his results, in which you
must recollect that the soft parts being absent, an additional source
MODES OF MEASURING THE PELVIS. 39
of error was removed (vide table*); you see that tliere is a full inch
difference in the thickness of the base of the sacrum, which would
be no trifling matter, if added or taken from the conjugate measure-
ment of the brim. These two instruments are the best known and
most frequently employed, especially on the continent. But there
are others also employed.
The late Mdme. Boivin, aware of the objection to Contouly's pel-
vimetre, thought that it might be improved, and she contriA'^ed an
instrument by which the antero-posterior distance was taken dif-
ferently. One curved rod was passed into the rectum to the pro-
montory. Another, sliding upon it, but capable of being raised to
a given angle, was passed into the vagina; when there, it was
pressed up to the pubis, and the angle formed between both rods
measured on a scale, gave the antero-posterior distance. If you
recollect the direction which the rectum takes, you will perceive
that the rectal-rod either passed to the left side of the promontory
or dragged the rectum out of its position in front of it. Much de-
pendance could not therefore be placed upon this.
Besides these modes of measuring the pelvis, none of which can
be depended upon, there are what have been called "digital mea-
surements;" or, in other words, the experienced accoucheur, from
constant habit, when he passes the fingers or hand into the vagina,
will form a very accurate estimate of the space in the pelvis. This
is done in different ways : if one or two fingers are pressed towards
the promontory of the sacrum, and if they at all approach it,
* In Fig. 1, pelvis, the distance was 3 inches.
4. I, OS
„ 5, J
fi 9JL3
„ 7, 1
„ 9, J
,. 11, '^
2|
2|
13,1
14. I.
12
13,
1.5 J
16, „ „ 2i
17, „ .. 2
40 LECTURES ON PARTURITION.
it is certain the promontory projects too much, otherwise this
never could happen, as you will find, if you try the experi-
ment on the dried pelvis, sometimes as much of the hand as
the vagina will admit, is introduced; if, the sacrum below the
promontory and the pubis are only touched, when the fingers
are separated, it indicates sufficient space ; if it be impossible to
separate them, the contrary: and from the degree to which the
fingers are compressed, the amount of disproportion is estimated.
In some instances it was impossible to get more than two or
even one finger within the pelvis.
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42 LECTURES ON PARTURITION.
LECTURE III.
MECHANISM OP PARTURITION.
Definition of Labour — Divisions of Labours by various Authors — Division into
Natural, Difficult, Preternatural, Complex — Definition of Natural Labour —
Stages of Labour. Arrangement of the Muscular Fibres of the Uterus, on the
External and Internal Surfaces. The Eifect produced by the Contraction of the
different Sets of Fibres — Manner in which the Dilatation of the Uterus is accom-
plished — Use of Liquor Amnii, Order of Uterine Contractions — Wigand's views
— Objections to them — Dewees' explanation of Uterine Action — Objections.
Different Conditions of the Os Uteri — Dilatable— Rigid — Inflamed. Influence
on the Action of the Uterus.
We are now prepared to enter on tlie consideration of Parturition ;
a subject wliicli embraces the most important questions we
bave to bring before you, and which will require your most
serious attention, in order properly to understand the principles of
midwifery.
At the termination of the period required for the complete
developement of the ovum, a new series of operations are entered
on, for the purpose of giving birth to the foetus which has been
matured; these are included under the term Labour. It usually
commences at the completion of the ninth month of gestation ; in
some instances it occurs before that time, when it is called Pre-
mature Labour. In this comprehensive sense, therefore, we
would define Parturition to be — the action of the uterus to expel
its contents when the foetus is sufficiently mature to sustain respi-
ratory life.
There are many circumstances depending either upon consti-
tutional peculiarities, irregular formation, or upon accident, which
may derange parturition or render it dangerous; hence, labours
have been divided and subdivided to meet these different condi-
tions. Some adopt only two divisions. The first includes those
labours which proceed regularly to their termination without
interruption. The second embraces those which do not do so.
DIVISIONS OF LABOURS.
43
The one is the rule, the other the exception; but as the excep-
tion includes several varieties, this second class is subdivided
into corresponding heads. Others place the most usual form
of labour, termed Natural, in the first, and then add separately
two, three, or four subsequent divisions, according to the import-
ance which they attach to these deviations. In this manner, from
two to seven divisions have been made, as you will perceive in
the table which is placed before you.
Divisions of Labours
BY Various Authors.
Natural /
Difficult 1 with 15 subdivisions or
Dvstocliia S orders.
Merriman
Eutochia (
. .
•â–
Natural j
Euiochia j
DyXchtil-''^^-^'^â„¢-
Rigby
Natural
Laborious Preternatural
Dewees
Natural
Unnatural with 6 orders
Complex
with 6 ord
. .
Churchill
Natural
Difficult
Preternatural
Complex
Denman
Natural
Instrumental
Preternatural 'Complex
Davis
Natural
Laborious
Preternatural! Anomalous
Flooding
Blundell
Natural
Premature
Preternatural
Tedious
Laborious
Impracticable
Complicated
Burns
These numerous divisions, to which many more might be
added, are a sufficient reason for not wishing to complicate the
subject by proposing another. It is preferable to adopt that
which is most generally known, quite as distinct, and is in many
respects more simple and practical, than some of those before you.
Denman's division is sufficient for our purpose ; we propose it to
you for your selection, and shall consider labour tinder the several
heads of Natural, Difficult, Preternatural, Complex. Denman de-
fines labour to be natural, ' ' if the head of the child present ; if
the labour be completed in twenty-four hours; and if artificial
assistance be not required." Labour is called preternatural, when
some other part than the head of the child presents. It is called
difficult labour, when it exceeds twenty-four hours; and complex
labour, when some accidental cause of danger occurs which may
render interference necessary.
It is of the highest importance that you should have a clear view
of the whole series of phenomena which constitute parturition;
for, unless you perfectly comprehend the changes which are going-
forward in the uterus, and have an accurate knowledge of the
means adopted by nature to accomplish her purpose, you can
never understand the principles of midwifery : your practice must
be empirical; and however indebted to chance you may be for
success, you will always be exposed to the risk of committing
* Denman, p. 165.
/
44
LECTURES ON PARTUEITION.
some fatal mistake. It, therefore, becomes our duty to explain to
you tlie series of operations, by wliicli tlie delivery of tke child is
effected. We would desire, at tlie same time, to direct your
attention to tlie beautiful application of mechanical contrivance
employed by nature to effect her object.
. In order to study parturition efficiently, it is necessary to divide
it into certain stages. The means by which the uterus is opened
is not the same as that by which the child is forced through the
pelvis; and again, the manner in which the placenta is separated
and expelled is different from either; hence, labour has been di-
vided into three stages, sometimes into four, and even five. The most
usual division is that of Dennian — the first stage being the dilat-
ation of the OS uteri ; the second^ the expulsion of the child ; and
the third, the separation of the placenta. Other authors subdivide
the first into premonitory and dilating stages, and some divide the
second stage into two, as you perceive in this table.
Stages of Labotie by different Authors.
\st Stage.
Premonitory
Premonitory
2nd Stage.
Dilating . .
Dilating . . .
Dilating . . .
Dilating .
Dilating .
3rd Stage.
Expulsive . . .
Expulsive
Passage throush
the pelvis.
Occipvit under the
arch of the pubis
Rupture of mem-
branes and pas-
sage of the head
Ath Stage.
Expulsion
Expulsion
Expulsion
5th Stage.
Placental
Placental
Placental
Placental
Placental
Authors.
Denman.
Velpeau.
Jno. Clark.
Merriman.
Naegele.
Of these divisions, we would propose to you that of Denman ;
it is the most generally adopted, and seems to be that which is
marked out by nature herself.
The first stage is dated from the opening of the os uteri to its
complete dilatation. Denman adds to this definition, the rupture
of the membranes and the discharge of the liquor amnii. This,
however, renders the division imperfect, because the membranes
often are not ruptured until late in the second stage, and occa-
sionally remain unbroken when the head is expelled. This addi-
tion, is therefore unnecessary, and causes confusion.
The second stage commences when the os uteri is perfectly di-
lated, and terminates in the expulsion of the child.
The third stage is occupied with the expulsion of the placenta.
Before describing the manner in which the dilatation of the uterus
takes place, it is necessary to recapitulate very briefly the arrange-
AREANGEMENT OF UTEEINE FIBEES.
45
ment of the muscular fibres of the uterus, which has been detailed
in a former lecture.
Muscular fibres on the external surface of the uterus, terminating in
the round ligaments a b.
The fibres on the external su7'face form two broad fan-shaped
muscular layers, spreading from the round ligaments over the fun-
dus uteri. On the intei'nal surface, there are three distinct sets of
fibres : two of these surround the Fallopian tubes in a concentric
arrangement. The third set pass circularly round the body of the
uterus, and the outer fibres of the two former layers gradually pass
into and intermix with those of the latter. The mass of fibres
lying between the external and the internal layers have no deter-
minate direction, but may be supposed to give increased power to
those we have described. Sir C. Bell, in his valuable paper " On
the Muscularity of the Uterus," has mentioned fibres which pass
in a " vertiginous" direction from the fundus to the mouth of the
uterus. Such, then, is the arrangement of the muscles or muscle
of the uterus, as far as it has been demonstrated. Let us now con-
sider their action. The external muscular layer slowly contracts
for some time before labour has actually commenced, and draws
the uterus gradually towards the pelvis. By this means, also, the
fundus is maintained in its proper direction, and prevented from
inclinino; too much to either side. This o-radual contraction is un-
accompanied by pain, and therefore is not taken notice of; but its
effect in alterino- the size of the abdomen, and makiuo- it less
46
LECTURES ON PARTURITION.
prominent, lias always been observed, and noted as a premonitory
sign of labour. These fibres also serve a useful purpose when the
dilatation of the os uteri commences : the fundus being thus sup-
ported, the fibres on the internal surface contract more eflhciently.
Exaggerated view of the fibres on the internal surface of the uterus :
a a, the orifices of the Fallopian tubes.
^<-^f^T7(.»r^<
^^'''
m-
Uterus inverted, to show the natural appearance of the fibres on its
internal surface.
The action of the internal sets of fibres requires a more careful
examination, inasmuch as different and, it appears to me, incorrect
EFFECT OF UTERINE CONTRACTIONS. 47
explanations liave been given both of the arrangement of these
fibres and of the manner in which they contract. Besides this,
it is necessary for you to have a correct view of uterine action, and
the order observed in these contractions, to enable you to notice
the deviations from it that occur. We shall therefore consider
each separately. First, the effect produced by the contractions of
the different sets of fibres. Secondly, the order in which these con-
tractions take place.
When the fibres surrounding the Fallopian tubes contract together,
the fundus uteri is equally diminished on all sides, and their com-
bined eifect, conveyed through the medium of the liquor amnii, is
precisely the same on the mouth of the uterus as if the fibres passed
down vertically and acted directly upon it. In order to render
this intelligible, I shall have to ask your patient attention for a few
moments.
The lines «, b, i-epresent the direction of the force of the fundal muscles :
c c/, the direction of that of the circular muscles of the body of the utenis:
d e, the combined force of these muscles.
The dotted i-ight lines represent the direction of the force reflected by
the liquor amnii ; the dotted curved lines, the direction of the circular
fibres of the body of the uterus.
Let US suppose a line {a d,') to pass from the opening of the
Fallopian tube of one side of the uterus to the opposite, in such a
manner as to represent the direction of the force of the fibres
48 LECTURES ON PARTURITION.
surrounding it. This line would pass obliquely downwards to tlie
opposite side. If, therefore, these fibres alone acted, the fundu,s on
that side would be diminished in its size, and the contents of the
uterus pressed toward the lower section of the opposite side, but
not against the os uteri. If, further, two such lines {a d), passing
from the orifice of each Fallopian tube represented the force of
each set of these concentric fibres, the intersection of these lines
would be the common point where these forces meet, and, to
a certain extent, are opposed. The combined force must, there-
fore, take an intermediate direction equi-distant from both lines,
which would be represented by a line (de) passing in the axis of
the uterus, and through the os uteri. It follows, therefore, that
when the fundus of the uterus contracts equally, the resulting
force must be communicated to the os uteri, as perfectly as if the
fibres passed vertically from the fundus to the mouth of the uterus.
When the circular fibres of the body and cervix contract, their ten-
dency is to render the uterus more and more cylindrical, according
to the degree of their contraction, at the same time that they
close in the cervix. Again, if the uterus were emptied of its con-
tents, the simultaneous action of all these difi^erent sets of fibres
would be, to draw the parietes equally towards the centre of the
cavity. But when the uterus is gravid, and makes an effort to
expel the foetus, they cannot all contract in this manner.
The fundal muscles are those which chiefly effect the dilatation
of the OS uteri and the expulsion of the child, the fibres of the
body and the cervix remaining comparatively passive. It has
already been explained to you, that their united action is in the
direction of the os uteri ; but there is still a necessity for a means
by whicli the result of that action should be perfectly conveyed
to it. This is accomplished by the fluid enclosed within the
amnion, which acts with a distending power upon the os uteri
exactly equal to the combined force of these muscles. The mus-
cular bands, described by Sir C. Bell, must also have the effect of
expanding the os uteri by drawing it upwards. The circular
fibres of the body and cervix resist the efforts of the fundus to
distend them ; and the force of their resistance is also communicated
to the contained fluid. This force is therefore, as it were, reflected
upon the os uteri, so that the whole uterus might be said to act as
one muscle in dilating the mouth. The os uteri has been generally
DILATATION OF OS UTERI. 49
considered to possess circular fibres, its action to resemble, in some
degree, the sphincter muscles in other situations, and its dilatation
to be the effect of their relaxation. The existence of these circtilar
fibres at the os uteri has never been proved. Hunter could not
demonstrate them; Sir C. Bell could not trace them out.* If a
sphincter muscle exist in that situation, why should not its fibres
be as distinct and as easily made out as the sphincters of other
hollow muscular viscera? Neither does the manner in which
the OS uteri dilates support this assertion. Its expansion is very
gradual, it yields slowly to the power described, and does not
resemble the comparatively sudden relaxation of a sphincter
muscle. Were it similar, rapid labours (at least so far as the
dilatation of the os uteri is concerned) would be the rule, not the
exception. It would be incorrect, then, to attribute the resistance
offered by the os uteri to muscular contraction. It seems more
probable, that the firm, highly-condensed tissue that forms the
cervix of the virgin uterus, still retains, in its altered state, many
of its original characters; that this tissue, although more unfolded,
is still sufficiently compact and elastic to offer a great degree of
resistance, and that its dilatation is effected by the incessantly
repeated efforts of the uterus slowly overcoming and expanding
it. Such a view seems to be fully supported by the observation of
labour in its first stage, where we can perceive the os uteri first
becoming thinner, and then progressively (not suddenly) opening.
It has been stated that the sudden relaxation of the mouth of the
uterus, after a continued contraction, can only be explained on
the assumption of its muscularity. The same effect, however,
* " I have not succeeded in discovering circular fibres in the os tinc£e coiTespond-
ing in place and office with the sphincter of the other hollow viscera; and I
am therefore inclined to believe, that, in the relaxation and opening of the orifice of
the uterus, the change does not result fi'om a relaxation of the muscular fibres
surrounding the orifice. Indeed it is not reasonable to conceive, that the contents
of the uterus are to be retained during the nine months of gestation by the action of
a sphincter muscle. The loosening of the orifice, and the softening and relaxation
which precedes labour, is quite unlike the yielding of a muscular ring." Sir C.
Bell, on the Musciilarity of the litems. — Med. Chir. Trans, vol. iv. p. 346.
Dr. William Hvmter, whose perfect accuracy of description is noAv established,
states, " The cervix uteri, where the pennifonn rugag are situated, had not such
regular nor so large fasciculi as the rest of the uterus. In the body of the utenis,
the fibres are very regularly circular. The fundus was made up of two concentric
circular planes of fibres, at the veiy centre of which was the orifice of the Fallopian
tube." — Anatomical Descriplion of Gravid Uterus, p. 27.
E
50 LECTURES ON PARTURITION.
may be observed in other tissues besides muscle ; tlie perineum,
for instance, often resists, for a long time, tbe action of tlie uterus,
and tlien yields suddenly to its full extent, so that the head
is most unexpectedly delivered, and yet the distended portion
of the peringeum is not muscular. Besides, these sudden di-
latations are only exceptions to the general rule. In ordinary
cases, dilatation occupies a certain period of labour (often a
very long one), and the mouth of the uterus yields very gradu-
ally to the power employed.
We would now direct your attention to the means provided by
nature, to prevent the danger which might arise during this pro-
cess. If the uterus exerted its full power upon the undilated os
uteri, and if the unyielding head of the child were driven forcibly
against it, the almost certain consequence would be, that the
irritation would excite increased resistance, and ultimately ter-
minate in inflammation of the mouth of the uterus. To obviate
such an effect, nature interposes a fluid medium between the power
and the resistance. The liquor amnii contained within the mem-
branes, occupies the cavity of the uterus, and when its parietes
contract upon it, the force exerted is (as we have explained) by this
means, accurately conveyed to the os uteri. Wlien the latter dilates
in the slightest degree, the fluid insinuates itself within the smallest
opening, and expands it by a direct lateral pressure against its edges.
The power of the uterus is thus made to act in the most favourable
manner for distending its mouth.
Other advantages are also gained. The os uteri may dilate
irregularly; but any attempts to overcome forcibly the undilated
portion, is prevented when the force is conveyed through a fluid,
which, while it readily yields to an undue resistance, still main-
tains an equable pressure upon the edges of the os uteri. Any
irregularity in the action of the uterine fibres, is also, to a certain
extent, obviated, because these contractions, although irregular,
being still conveyed by the fluid, are thus equally communicated
to the OS uteri. Further, so long as the tissue of the uterus in-
tervenes, it is necessary to moderate the great power which the