GB2114892A - Obstetric forceps - Google Patents

Abstract

Obstetric forceps 10 have saucer-shaped blades 24, 40 pivotally mounted on the spatulate end of shanks 12, 30 which are pivotally mounted at 16. The blades may be maintained in position by nut 46 running on the pivoted threaded rod 44 co-operating with the forked extension 17. The forceps may have attached thereto at 16 a traction application means including a chain which is pivotable with respect to the shanks. <IMAGE>

Description

SPECIFICATION Obstetric forceps This invention relates to obstetric forceps.

There are currently two techniques in use for delivering a baby operatively from a vagina. The first technique involves the application of suction to the baby's head and is known as the Ventouse.

A cup is attached to the baby's head and suction is applied through a tube extending from the body of the cup and which is connected at its free end to a pump and an indicator. Traction is applied to the cup through a series of protected chains attached to a central point on the cup. The Ventouse technique has the following disadvantages:~ 1. It takes a long time to set up.

2. It is very fiddly to perform and needs two operators.

3. The cup tends to slip from the baby's head and time is wasted in re-setting it and re-forming the vacuum.

4. Damage to the skin on the baby's head and/or to its brain may occur if the technique is not properly performed.

5. Damage to the vaginal wall may result if the cup is erroneously applied to any part thereof.

The second technique involves the use of obstetric forceps. Conventionally these take the form of two long shanks which are arranged to be lockable at their proximal ends and which terminate at their distal ends each in a blade having the form of a loop resembling the peripheral portion of an elongate spoon. Each shank has a laterally outward curve to allow the baby's head to be accommodated between the blades, the cephalic curve, and a pelvic curve in a plane perpendicular thereto to take the shape of pelvic cavity. The conventional forceps have the following disadvantages:~ 1. The head is fixed in whichever way the forceps are applied: the baby's head cannot flex or deflex and will be delivered presenting whatever diameter or in whatever orientation it is held by the forceps.

2. The forceps are an entirely rigid structure when in use and, once they have been applied, the baby's head cannot rotate by itself around the spinal axis, in other words the baby's head will be delivered in whatever position it is caught by the forceps. Although forceful and risky rotation of the baby's head may be performed by a skilled obstetrician using a straight forceps without the aforementioned pelvic curve, for example a pair of Kiellands forceps, this is a risky procedure which may well cause severe damage to the baby and/or to the mother.

The above-described disadvantages of the conventional forceps are overcome by the forceps according to the present invention in their preferred form.

According to the broadest aspect of the present invention there are provided obstetric forceps comprising a pair of shanks, locking means for mutually locking the proximal ends of the shanks and a pair of generally saucer-shaped blades, each blade being mounted on the distal end of a respective shank for rotation about an axis passing perpendicularly through the centre of the blade, the arrangement being such that in their locked condition the shanks have a wishbone configuration and are restrained from mutual separation in a direction perpendicular to their general plane, and the blades are positioned with their concave surfaces mutually opposed. The rotatable blades allow the baby's head to flex and deflex, and assume during delivery the orientation presenting the most appropriate diameter.

Preferably each shank is only about 10 cm long, that is only half the length of a shank in a pair of conventional forceps; and the forceps according to the present invention additionally comprise traction application means which are arranged to be connectabie at one end to the proximal ends of the shanks and at the other end to be grippable by the obstetrician, said one end being rotatable relative to said other end to permit rotation of the baby's head about its spinal axis when traction is applied during delivery. Preferably the traction application means comprise a chain, suitably of a length of 10 cm, having at one end a hook or peg which is passed through apertures formed through the proximal ends of the shanks, the apertures being in register when the shanks are in the locked condition, and at its other end with a transverse handle.Passage of the hook or peg through the apertures prevents mutual separation of the proximal ends of the shanks in any lateral or longitudinal direction, but permits limited pivotal movement. Adjustment means may be provided to allow the blades to be closed together after application of the blades to the baby's head and maintained in position during delivery, thus ensuring a good grip.

If the shanks are fashioned in their preferred shorter form with only the cephalic curve and lack the conventional pelvic curve, the forceps according to the present invention, in which the traction application means replace the proximal portions of the conventional shanks, will allow rotation of the baby's head through 90 or 1 800 after the forceps have been placed therearound without causing foetal or maternal damage.

On the other hand, for use when the baby's head is in a normal occipito-anterior position, the shorter shanks of the forceps according to the present invention may be fashioned also with the conventional pelvic curve and a handle at their proximal ends, allowing the forceps to be used in the normal way while affording the advantage of free flexing and deflexing of the baby's head. If, however, such pelvically-curved forceps are used with the traction application means, minor corrective rotation of the baby's head around the spinal axis is also allowed without risk of mishaps because, firstly, the shorter blades eliminate risk of damage during rotation and, secondly, because the chance of a major rotation from the normal head position to an abnormal head position is very slim indeed.

The locking means are usually arranged, in the conventional way, to prevent mutual separation of the shanks in one sense but to permit relative longitudinal sliding movement to assist correct placing of the blades, particularly in cases of asynclitism.

From the foregoing it will be appreciated that the absence of the long conventional blades makes the application of the forceps according to the present invention much easier and safer, particularly if the operator is not a fully skilled obstetrician.

Although the invention may be carried out in a variety of ways, one particular embodiment thereof will now be described, by way of example, with reference to the accompanying drawings in which Figure 1 is a side elevation of a pair of obstetric forceps according to the present invention in locked condition and in conjunction with traction application means, intermediate portions of the forceps and traction application means being omitted; Figure 2 is a plan view, partly broken away of the forceps of Fig. 1; Figure 3 is a detail of the forceps of Fig. 1 in unlocked condition.

As shown in the drawings a pair of obstetric forceps 10 comprises a right shank 12 terminating at its proximal end in a rectangular section handle 14 through which is drilled a circular aperture 16 and which has a fork 17 projecting from the butt thereof. The shank 12 is formed with an outward cephalic curve and broadens towards its distal end to form a spatulate end portion 20 which is apertured to receive for rotation a rivet 22 solid with a saucer-like blade 24 of a diameter from 5 to 7 cm and having concentric grooves 26 in its inwardly facing concave face. The lateral edges of the end portion 20 are continued to form a circular section loop 27 on the root portions of which are received rotatable sleeves 28.

The left shank 30 is generally similar and has a handle 32 through which there is formed an aperture 34. Extending from the handle 32 is an L-section clip 36, the outer portion of which has an aperture 38. At its distal end the left shank 30 has a rotatably-mounted blade 40, facing the blade 24. Projecting from the butt end of the handle 32 is a cranked integral extension 42 on which is pivotally mounted a threaded rod 44 having a bulbous end 45 to retain a wing nut 46 received thereon.

In use, each of the shanks 12 and 30 is introduced separately into the vagina with the blades 24 and 40 being placed in the desired positions against opposed sides of the baby's head. The handle 14 of the shank 12 is then placed against the handle 32 of the shank 30 and within the clip 36 so that all three apertures 16, 34, 38 are in register. To apply traction there is employed a traction application assembly 50 which comprises a chain 52 of about 10 cm in length attached at one end to the shank of an L-shaped peg 54 the projecting portion 56 of which is formed with an annular stop 58 and a terminal pivoted retaining catch 60. At its other end the chain 52 is connected to a transverse handle 62.

The peg 54 is passed through the registering apertures 1 6, 34, 38 and with the catch 60 in the aligned position, the catch 60 then being rotated to the transverse position to help to lock the shanks 12, 30 in the correct relative positions by permitting only pivotal relative movement. As the surgeon pulls on the handle 62 to deliver the baby rotation of its head about the spinal axis is permitted by virtue of the rotational freedom imparted by the chain 52 and flexional movement permitted by virtue of the rotatability of the blades 24, 40 relative to the respective shanks 12, 30.

The sleeves 28 permit the baby's head to flex comfortably within the forceps 10. If desired the relative angle of the shanks 12, 30 may be reduced and guarded against subsequent increase by engaging the nut 46 against the fork 17 to provide the grippability afforded by conventional forceps. Furthermore, the blades 24, 40 may be inclined slightly inwards to guard further against slipping, It will be noted that the relative configuration of the handle 14 and the clip 36 permits limited pivotal movement when the peg 54 is inserted, and that a portion of the clip 56 is removed at 57 to permit wider opening of the blades 24, 40 to accommodate large heads.

Not only do the forceps 10 afford numerous advantages in both normal and abnormal cephalic presentations but they may also be used in the case of an aftercoming head in a breech delivery, or extraction of an impacted head in Caesarian sections.

The flat disc portion of the shanks and the blades could be modified by forming them with a large central aperture resembling that of conventional forceps and arranging for them to be peripherally mounted.

Claims (11)

1. Obstetric forceps comprising a pair of shanks, locking means for mutually locking the proximal ends of the shanks and a pair of generally saucer-shaped blades, each blade being rotatably mounted at the distal end of a respective shank, the arrangement being such that in their locked condition the shanks have a wishbone configuration and are restrained from mutual separation in a direction perpendicular to their general plane, and the blades are positioned with their concave surfaces mutually opposed.

2. Forceps as claimed in Claim 1, in which the shanks terminate in the region of the locking means.

3. Forceps as claimed in Claim 1 or 2 and which additionally comprise traction application means which are arranged to be connectable at one end to the proximal ends of the shanks and at the other end to be grippable by the obstetrician, said one end being rotatable relative to said other end to permit rotation of the baby's head about its spinal axis when traction is applied during delivery.

4. Forceps as claimed in Claim 3, in which the traction application means comprise a flexible element having at one end engagement means arranged to engage the proximal ends of the shanks when in the l#ocked condition.

5-. Forceps as claimed in Claim 4, in which the traction application means further comprise a handle attached-to the other end of theflexible element.

6-. Forceps-as claimed- in Claim 4 or 5 in which the flexible element is a chain.

7. Forceps as claimed in Claim 4, 5 or 6, in which the engagement means comprise a peg engageable in apertures in the shanks which are arranged to be in register when the shanks are in the locked condition.

8. Forceps as claimed in any preceding claim and further comprising pivotal connection means for pivotally connecting the- shanks.

9. Forceps as- claimed in Claims 7 and 8 in which the pivotal connection means comprise said peg.

10. Forceps as claimed in any preceding claim and additionally comprising adjustment means for adjusting the relative angle of the shanks and preventing subsequent increase of that angle,

11. Forceps as claimed in any preceding claim and additionally comprising adjustment means for closing the blades together after application thereof to the baby's head and mounting them in position.

Claims 11-18 renumbered as Claims 12-19 and appendances corrected.

11. Forceps as claimed in any preceding claim, in which the locking means comprise an L-shaped projection on one shank in which the other shank is slidably receivable.

12. Forceps as claimed in any preceding claim, in which the shanks are formed without a pelvic curve.

13. Forceps as claimed in any preceding. claim, in which each shank extends beyond the respective blade mounted thereon.

14. Forceps as claimed in Claim 13, in which each extension has the form of a projecting loop.

15. Forceps as claimed in Claim 13 or 14, in which each extension is provided with at least one roller arranged for rotation about an axis in general alignment with the respective shank.

16. Forceps as claimed in any preceding claim, in which the concave surface of the blades is roughened to enhance their grip on the baby's head.

17. Obstetric forceps as claimed in Claim 1 and substantially as herein described.

18. Obstetric forceps substantially as herein described with reference to the accompanying drawings.

New claims or amendments to claims filed on 18 May 1983.

New or amended claims:~