Part 15 (2/2)

The lock of the modern English forceps consists of two deep grooves, into which the shank of each blade mutually fits, so that the two blades are fixed upon each other merely by the pressure exerted upon the handles. In former times the blades were united together by a pivot, which could screw and unscrew at pleasure. This was abandoned by Chapman, who published the first work in English on operative midwifery.[82] He found that the forceps held better without the pivot than with it; and from what we have brought forward elsewhere (_Med. Gaz._ Jan. 8, 1831,) there can be little doubt that he invented the lock which is now generally used in this country. Chapman's forceps was adopted in France prior to this improvement in its lock, especially by Gregoire, and has retained the original pivot lock which now forms one of the most distinguis.h.i.+ng marks between the French and English forceps. Although the pivot forms by far the firmest lock, for the blades can never slip from each other, still the difficulty in locking, and also in separating, the blades at a moment's notice, render it much inferior to the English lock. An ingenious modification was invented by the late Professor Von Siebold of Berlin, but the most perfect lock is that of Professor Bruninghausen of Wurzburg, first introduced by ourselves into this country, and commonly known among the instrument-makers under the name of Professor Naegele's forceps. The shank of one blade has a semicircular indentation, which at the moment of locking fits into a fixed pivot in the other: this, therefore, combines the advantages of the French and English locks. We can safely affirm, from extensive experience for many years, that there is even less difficulty in locking it than with the English lock: the blades are capable of instant separation, and yet when locked, the firmness of their union is equal to that of a pivot joint.

The handles of the English forceps are pieces of wood or ivory fixed upon each shank below the lock, flat upon the inside, convex externally and furnished with a depression or groove at the lower end for fixing a ligature round them. These handles were probably first introduced by Dr.

Smellie, who seems to have borrowed the idea from the forceps of M.

Mesnard, for the earlier English forceps, viz. of Giffard and Chapman, terminated in blunt hooks, those of the former being curved inwards, those of the latter outwards, a form of handle which has been retained in the French forceps up to the present time.

There are two pieces of forceps, the _long_ and the _short_ forceps; the former for cases where the head is still high in the pelvis, the latter when it is at the pelvic outlet and approaching the os externum; the former with few exceptions being curved, the latter straight.[83]

The forceps act in three ways, 1. by mere pulling; 2. as a species of double lever, by moving the handles from side to side; and 3. by compressing the head, thus still farther disposing it to elongate and adapt itself to the pa.s.sage through which it has to be expelled.

The blades should always, if possible, be applied one on each side of the head, the position of which must be determined by the direction of the fontanelles and sutures, not by feeling for the ear, as is usually recommended in this country. The ear can seldom be reached without causing a good deal of pain, even under the most favourable circ.u.mstances; in cases, therefore, where the head is so impacted as to be incapable of advancing by the natural powers, it cannot surely be justifiable to force up the finger between the head and the pelvis to ascertain this point, the more so, as the soft parts soon become swollen and more or less inflamed, and, therefore, little able to bear such rude treatment. No operation requires such an intimate acquaintance with the mechanism of parturition as that for applying the forceps: it is simple and generally perfectly easy when the precise position of the head and its relations to the pelvis are accurately known; on the other hand, it is not less injurious and painful to the patient than difficult and unsatisfactory to the pract.i.tioner.

The most usual circ.u.mstances under which the forceps is applied, are where the head is already deep in the pelvis and approaching the os externum; in such cases it is generally required not so much for the purpose of overcoming an unusual degree of resistance, as for a.s.sisting the natural powers, which are becoming exhausted: the head is near the os externum, and therefore easily reached; and from there being little or no impaction present, the blades are applied without difficulty.

The application of the forceps when the head is at the upper part of the pelvis, and where the greater portion of it has not yet pa.s.sed the brim, is rarely practised in this country, because as the necessity for performing the operation at this stage arises in most instances from contraction of the brim, the perforator has usually been preferred, wherever the expelling powers have proved incapable of overcoming the resistance to the pa.s.sage of the head. The circ.u.mstance also of this condition requiring the long forceps has been another source of objection, from the much greater power which this instrument is capable of exerting, and from its being therefore more liable than the short forceps to prove mischievous in the hands of the inexperienced.

Cases however do occur where there is but a very slight want of proportion between the head and pelvis, where the obstacle is easily overcome, and where, but for the application of the forceps, the labour would either have been protracted to a dangerous degree, or have required the use of the perforator.[84] ”On the whole,” says Dr. Burns, ”I would give it as my opinion that a well instructed pract.i.tioner, who has already had some experience in the use of the short forceps, is warranted to make a cautious, steady, but gentle attempt to apply and act with the long forceps in a case where he is not quite decided that the perforator is indispensable, and where the head is higher than admits the application of the short forceps.” (_Principles of Midwifery_, 9th ed. p. 493.)

In applying the forceps, whether short or long, there are two conditions which, _caeteris paribus_, are requisite in every case; first, that the os uteri shall be fully dilated; secondly, that the pains are within the bounds of what are commonly known as moderate pains. In the first case it will be very difficult and frequently quite impossible to pa.s.s the blades between the head and os uteri when only partly dilated; it will be difficult to avoid injuring its edge more or less, and if we do succeed in applying and locking the forceps, on making an extractive effort we shall find that the uterus descends with the head as we draw it down.

In the second place we ought never to apply the forceps whilst the pains are violent, for not only do they render its application difficult and even dangerous, but we are adding still farther to the force (already too great) with which the head is pressed against the pelvis. Where the head remains immoveable under violent exertions of the uterus, it is not a case for the forceps but for the perforator; nor does it admit of much delay, for it endangers much injury of the soft parts or even rupture of the uterus.

It is exceedingly difficult to a.s.sign any precise limits of pelvic contraction, within which the forceps can, and beyond which they cannot be applied, for the size and hardness of the foetal head, the nature of the pains, and the condition of the patient must also be taken into account in every instance; hence, we frequently meet with cases where the pelvis is scarcely if at all contracted, and yet where the labour has been terminated with the greatest difficulty by means of the forceps; whereas, in others where we know the pelvis to be more or less deformed, the child has been delivered by the natural powers. This subject will be still farther considered under DYSTOCIA PELVICA.

The _general indications_ for the use of the forceps are two: 1. They are indicated in all labours which are difficult or impossible to complete, either from deficiency in the expelling powers, or from misproportion between the head and pelvis, or from the arm coming down with the head. 2.

They are indicated by circ.u.mstances or accidental causes, which render labour dangerous for the mother or child, and where the danger can only be removed by hastening labour, as in cases of haemorrhage, convulsions, syncope, alarming debility, faulty condition of the organs of respiration, danger of suffocation, obstinate vomiting, unusually severe pains in nervous irritable habits, hemorrhoids which have burst, hernia, retention of urine, determination of blood to the head, prolapsus of the cord, (in certain cases,) inflammation of the uterus, &c. (Naegele, _MS. Lectures_.)

We have already stated that an intimate acquaintance with the mechanism of parturition is of the greatest importance in applying the forceps. Knowing that the head always presents in one of the two oblique diameters of the pelvis, and that the blades are applied on each side of the head, it follows that the forceps must always be applied in the contrary oblique diameter of the pelvis to that in which the head is. Before speaking of the operation itself, we must first consider what position of the patient will be the most convenient. In this country no alteration is made in her position, beyond bringing her close to the side of the bed, with the nates projecting as much as possible over the edge, for the greater convenience of the operator; unless this be attended to, it will be difficult to depress the handle of the upper blade sufficiently when introducing it.

Upon the continent, and also in America, where the long forceps is more generally used, the patient is usually delivered on her back; she is placed in a half-sitting posture upon the edge of the bed, her back supported by pillows, &c., her feet resting on two chairs, between which the operator stands or sits, and applies the forceps in this position.

This, in many respects, is the most convenient posture for him, but the very preparation which it requires cannot but be alarming to the patient, who is obliged to be a witness of all his manipulations; whereas, when she lies upon her left side, she is aware of little or no preparation being made, and if any slight exposure happens to be necessary, viz. at the moment of locking, it can be done without her knowledge.[85]

The simplest case for applying the forceps is, where the head has already descended nearly to the os externum, and has begun to press upon the perineum: it is for this that the straight forceps is chiefly intended; and as this is the instrument which is generally used, we shall describe its application first.

_Mode of applying the forceps._ Having ascertained that the r.e.c.t.u.m and bladder are empty, examined the position of the head, and warmed and greased the blades, we proceed to introduce the upper or lower blade first, according as its lock is directed forwards: this precaution is for the purpose of preventing the locks being turned away from each other when brought together after the introduction of the second blade. The trochanter major will guide us as to the precise position of the patient's pelvis, and is especially useful in pointing out the direction of the left oblique diameter, in which the forceps (on account of the first position of the head being in the right oblique diameter) should be most frequently applied: in this case, we pa.s.s the upper blade, as it were, beneath the trochanter, and the lower one in the opposite direction.[86]

Let us suppose that the head is in the first position, with its sagittal suture parallel with the right oblique diameter of the pelvis, and that in accordance with the above rule, the upper blade is to be introduced first.

Having pa.s.sed one or two fingers up to the head, we guide the blade along them, depressing the handle so as to make the extremity of the blade lie closely upon the head, neither allowing the point alone to impinge upon the head, nor _vice versa_, to protrude against the v.a.g.i.n.a. The extremity of the blade, therefore, must be our guide for the direction in which we hold the handle: we must carefully insinuate this by a gentle vibratory motion between the head and pa.s.sage which surrounds it: the convexity of the head will show the course which it has to take, nor is there any need of pa.s.sing the finger farther; for when once the extremity of the blade is fairly engaged between the head and pa.s.sage, it will almost guide itself, and needs little more than to be pushed on gently, the handle gradually rising according to the curve of the blade. The shank or handle should, therefore, be held lightly like a pen, by which means the operator will possess much more feeling with his instrument, than if he grasped it with his whole hand. As the blade advances, he should keep his eye on the general form of the pelvis, the curve of the loins, the situation of the trochanter and symphysis pubis, and thus gain a more accurate idea of the course which the instrument must take. This will, in great measure, depend upon the situation of the head: if it be quite down upon the perineum, the blade should be pointed towards the promontory of the sacrum, and the handle turned downwards and forwards; if it be still in the cavity of the pelvis, and only beginning to engage in the outlet, the blade must be directed upwards towards the centre of the brim, and the handle turned directly downwards. Having pa.s.sed the blade to its full extent, we must press the handle backwards against the perineum, to allow sufficient room for the introduction of the second blade, and give it to an a.s.sistant or the nurse, with the caution to hold it steadily and firmly, especially during the pains, when it is apt to slip into the hollow of the sacrum if held carelessly.

As we have pa.s.sed the upper blade behind the right acetabulum or foramen ovale, so now we must introduce the other in the opposite direction, viz.

before the left sacro-iliac synchondrosis: and, as the blades being exactly opposite to each other is essential to the easy locking of the instrument, it will be necessary to guide the course of the second blade, not so much by the form of the pelvis, as by the direction of the first blade. It must, therefore, pa.s.s up, so that when introduced to its full extent, the inner surface of its handle shall correspond precisely to that of the first blade. The easy or difficult locking of the blades is a proof of their having been correctly or incorrectly introduced. If, therefore, on bringing the locks together we find that they do not correspond, that the inner surfaces of the handles are not parallel, but form an angle with each other, we must endeavour to rectify this, by withdrawing, to a short extent, that blade which deviates most from the proper direction, and pa.s.s it up again more correctly. All attempts to twist the handles so as to correspond with each other, are bad and cannot fail to put the patient to much suffering.

When we are about to lock the blades, we cannot be too careful in preventing the soft parts from being pinched between them, for it causes most intolerable pain, and frequently makes the patient give such an involuntary start, as to run the risk of altering the position of the instrument.

<script>