A System of Midwifery

by Edward Rigby

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 rectum 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 pass 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 passed 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 versâ, to protrude against the vagina. 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 passage which surrounds it: the convexity of the head will show the course which it has to take, nor is there any need of passing the finger farther; for when once the extremity of the blade is fairly engaged between the head and passage, 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 passed 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 assistant 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 passed 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, pass 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 pass 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.

The whole process of introducing and fixing the forceps should be conducted in as gentle and gradual a manner as possible: no attempt should be made to proceed with the operation during a pain; and in no case is force either necessary or justifiable.

Every thing being now prepared for the extraction, we must endeavour to make this resemble as far as possible the natural expulsion. When a pain, therefore, comes on, we should grasp the handle firmly, and pull gently, at the same time giving them a rotatory motion. The direction of the handles, as before said, will depend upon the situation of the head in the pelvis: if it be at the outlet, it will point downwards and forwards; if in the cavity, nearly directly downwards. If the head makes but little or no advance with one or two efforts, it will be advisable to tie the handles firmly together, and thus keep up a continued pressure upon it, and dispose it the more to elongate and adapt itself to the passages. As it advances and begins to press upon the perineum, we must be more than ever cautious not to hurry the expulsion, and give the soft parts time to dilate sufficiently. At this period it is desirable to make the extractive effort not so much forwards as the direction of the handles would seem to indicate: we thus avoid pressing too severely upon the urethra and neck of the bladder, which might otherwise suffer, and assist the dilatation of the perineum. When the head is on the point of passing the os externum, all farther extractive efforts should cease; the perineum must be supported in the usual manner, and the head should be expelled if possible by the patient herself.[87]

In applying the curved forceps we must bear in mind another rule in addition to the one above-mentioned for selecting the first blade, viz. the pelvic curvature must correspond with that of the sacrum. As with the straight, so also with the curved forceps, the extremity of the blade will be our best guide as to the direction in which we should hold the handle at the moment of introduction; it must be directed more or less forwards in proportion to the degree of the pelvic curvature of the blade. If, for instance, it be the upper blade which is to be introduced first, we pass it obliquely over the lower thigh or nates of the mother, making it glide closely round the convexity of the head, between it and the pelvis, without impinging either on the one or the other. As the position of the head is still more distinctly oblique at this earlier period of its progress through the pelvis, so will the blades require a more oblique direction, and also (as in the former case) they must be introduced in the contrary oblique diameter to that in which the head is.

As the blade passes up between the head and pelvis, so does the handle gradually make a sweep backwards, until at length it approaches to the edge of the perineum. During the process of introduction, one or two fingers should press against the posterior edge of the blade to guide it up to the brim of the pelvis, and prevent its slipping too far backwards towards the hollow of the sacrum.