WO2002100259A1

WO2002100259A1 - Device for determining foetal reserves during childbirth

Info

Publication number: WO2002100259A1
Application number: PCT/NL2002/000367
Authority: WO
Inventors: Paul Isodore D'hond; Mathijs Lodewijk Ten Berg; Rebindrenath Rock Goerdin
Original assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
Priority date: 2001-06-08
Filing date: 2002-06-05
Publication date: 2002-12-19
Also published as: NL1018249C2

Abstract

A device for determining foetal reserves of a foetus during childbirth, provided with a tubular housing which is arranged to be inserted in use, into a vagina of a pregnant woman to reach a presenting part (generally a head) of the foetus, the tubular housing being provided at a first free extremity of the tubular housing with access means for obtaining access to body fluid such as blood or interstitial fluid of the foetus whose reserves need to be determined, the tubular housing being further provided with at least one contact-pH-sensor and/or one lactate-sensor for measuring, by means of contact between the body fluid and the pH-sensor and/or the lactate-sensor, the pH-value and/or a lactate-value, respectively, of the body fluid to which access has been obtained with the aid of the access means.

Description

Title: Device for determining foetal reserves during childbirth.

The invention relates to a device for determining foetal reserves of a foetus during childbirth, provided with a tubular housing arranged for being inserted, in use, into a vagina of a pregnant woman as far as a presenting part (usually a head) of the foetus. Such a device is known per se. During childbirth, due to various circumstances, lack of oxygen can occur in the foetus. This may result in irreversible brain damage. In general, when there is a threat of lack of oxygen, a caesarian section is decided upon. Currently, to determine what the foetal reserves are, chiefly the experience and the impressions of the physician are relied upon. To that end, he also utilizes the CTG-diagram. However, in this manner, it is very difficult to obtain a correct impression of the foetal reserves. Sometimes, also a pH-determination is carried out by taking a blood sample of the foetus. This determina ion gives a scientifically accepted indication about the foetal reserves. By carrying out the determination repeatedly, also an insight into the trend development is formed. However, carrying out such a measurement with the aid of a device according to the state of the art is laborious and particularly burdensome to the mother, Nowadays, this method is sometimes used in teaching hospitals but, in general, is passing into disuse. Currently, the physician mainly relies upon his own impression and experience. Consequently, the dilemma occurs at what moment to opt for a caesarian section. On the one hand deciding too late for a caesarian section or, on the other hand, in retrospect, not necessary. Due to the possible risks and the uncertainty about the real foetal reserves, generally, at some indication of imminent ϊack^:όf oxygen; a- caesarian section is opted for. In those^" cases where use is made of the known device for determining foetal reserves, additionally, the following can be noted.

With the known device, the tubular housing comprises a trocar which, during childbirth, is inserted into the woman for obtaining a view of the head of the foetus. Further, via this trocar, all operations are carried out for taking a blood sample of the foetus. These operations consist of cleaning the head with the aid of swabs for preventing amniotic fluids and blood of the mother from mixing with the foetal blood sample to collect. Then, optionally, the head is moisturized with a spray for inducing vascular stasis whereupon an incision is made in the presenting part of the foetus. To prevent CO3 from diffusing with the blood, a surface tension is created with the aid of vaseline. As a result, a higher surface tension is created. Then, the blood is removed via a long thin tube, by means of, for instance, capillary action of the tube or through suction with the mouth. Eventually, the physician will fill an analysis tube with the blood, whereupon the blood is analyzed in the laboratory.

The use of such a device entails a number of drawbacks. The time required for the entire process is long. The operations to be carried out for obtaining a reliable blood sample without mucus and other body fluids require great effort, ergonomic discomfort and adroitness of the physician. The view the physician has via the trocar is limited. The method carried out with the aid of the trocar is painful and uncomfortable to the mother because she is in the lithotomy position.

The invention contemplates providing a solution to the problem mentioned.

Accordingly, the device according to the invention is characterized in that at a first free extremity of the tubular housing, the tubular housing is provided with access means for obtaining access to body fluid, such as blood or interstitial fluid, of the foetus whose reserves are to be determined, and in that the tubular housing is further provided with at least one pH-sensor and/or one lactate-sensor for measuring, by means of contact between the body fluid and the sensor, a pH- value and/or a lactate-value, respectively, of the body fluid to which access has been obtained with the aid of the access means.

As the device is provided, in combination, with the access means and the at least one sensor, in a simple and rapid manner, the pH-value and/or the lactate-value of the body fluid can be determined for determining the foetal reserves of the foetus during childbirth. Body fluid, for instance blood, no longer needs to be taken to the laboratory to be analyzed. This saves an enormous amount of time. As, moreover, the tubular housing is provided with the access means, these can be arranged such that they can be operated by a physician in a simple manner without this requiring a large amount of experience. As a result, both physician and patient need to make little effort while the treatment is not painful or uncomfortable to the expecting mother. According to a first possible further elaboration of the device according: to the invention, it holds that the access means are provided with a small knife for making an incision in the presenting part of the foetus for . obtaining blood from the foetus, while the pH-sensor andJor the lactate-sensor are positioned such that the blood obtained from the foetus comes into contact with the pH-sensor and/or the lactate-sensor. In particular, if holds that the small knife is connected to the tubular housing so as to be movable over a limited path for performing a controlled incision. In this variant, the incision can be performed particularly accurately without special experience of the physician being required.

Preferably, it further holds that the vacuum element is provided with at least one flexible suction mouth. It appears that when the first free extremity is fixed to the presenting part of the foetus, performing an incision can then be done with even greater accuracy and precision. Also, it is thus effected that the body fluid can be accurately brought into contact with the respective sensor. Preferably, in that case, it holds that the vacuum element is provided with a flexible suction mouth. Thus, an optimal airtight contact is obtained between the vacuum element on the one side and the presenting part on the other side.

_ Preferably, it holds that the tubular housing is further provided with cleaning means for cleaning the presenting part of the foetus before the incision is made. It is important that the blood sample be taken as cleanly as possible before a reliable measurement can be carried out.

According to a first alternative embodiment of the device according to the invention, it holds that at the first free extremity, the tubular housing is further provided with a vacuum element for fixing the first free extremity, in use, by means of a reduced pressure, against the presenting part of the foetus and for withdrawing interstitial body fluid, by means of the reduced pressure, from the presenting part of the foetus, while the pH-sensor and/or the lactate- sensor are positioned such that the interstitial fluid obtained from the foetus comes into contact with the pH- sensor and/or the lactate-sensor. An advantage of this variant is that no incision needs to be made. The interstitial body fluid which is withdrawn from the presenting part of the foetus then makes contact with the respective sensor for measurement of the pH-value and/or lactate- value mentioned. According to a second alternative further elaboration of the device according to the invention, it holds that access means and the pH-sensor and/or the lactate-sensor comprise a fiber which, on an outside of the fiber, is at least partly covered with a pH- and/or a lactate-sensitive coating forming a sensor surface of the sensor, while the device is arranged for moving a free extremity of the fiber outside of the tubular housing at the first free extremity of the tubular housing for penetrating the presenting part of the foetus so that in the foetus, body fluid comes into contact with the coating. In this manner, also, no body fluid needs to be withdrawn from the foetus for determining the pH-value and/or lactate-value. This, in turn, has as an advantage that prior to the determination of the pH- and/or lactate-value, cleaning of the presenting part does not need to take place,

In this variant also, it preferably holds that the fiber is provided in the tubular housing while the tubular housing is provided at the first free end with an opening through which, in use, the free extremity of the fiber can be moved outwards for carrying out the penetration. In particular, it holds that at its first free extremity, the tubular housing is further provided with a vacuum element for fixing the free extremity, in use, by means of a reduced pressure, against the presenting part. In this manner, placing the free extremity of the tubular housing against the presenting part is simplified for the physician because he can see exactly where the respective part is located.

The tubular housing can also be designed as a disposable article. This has a great hygienic advantage.

In particular, it holds that in the tubular housing, an electric circuit is included which is connected to the pH-sensor and/or the lactate-sensor, while, on an outside of the housing a display connected to the circuit is arranged for displaying the

pH-value and/or the lactate-value. As a result, the device is a stand-alone device which, in combination, comprises providing access to the body fluid, measuring on the body fluid and then determining and displaying the pH-value and/or the lactate-value.

The invention will be further elucidated with reference to the drawings.

In the drawings:

Fig. 1 shows a de ice and method according to the state of the art; Fig. 2a shows a longitudinal cross section of a first possible embodiment of a device according to the invention;

Fig. 2b shows a top plan view of a small knife of the device according to Fig. 2a in the direction of the arrow P of Fig. 2a;

Fig. 2c shows a cross section of the device according to Fig. 2a; Fig. 3a shows a longitudinal cross section of a second possible embodiment of a device according to the invention;

Fig. 3b shows a top plan view of a needle-shaped small knife of the device according to Fig. 3a in the direction of the arrow P of Fig. 3a;

Fig. 3c shows a cross section of the device according to Fig. 3a; Fig. 4a shows a longitudinal cross section of a third possible embodiment of the device according to the invention;

Fig. 4b shows a top plan view of a collecting channel of the device according to Fig. 4a in the direction of the arrow P of Fig. 4a; Fig. 4c shows a cross section of the device according to Fig. 4a:

Fig. 5a shows a longitudinal cross section of the fourth possible embodiment of the device according to the invention;

Fig. 5b shows a top plan view of a coated fiber of the device according to Fig. 5a in the direction of the arrow P of Fig. 5a; and Fig, 5c shows a cross section of the device according to Fig. 5a.

In Fig. 1, with reference numeral 1 a known device is indicated . which is used when determining the foetal reserves of a foetus during childbirth. Here, in the example of the state of the art, the pH-value of the blood of the foetus 2 is measured. The device 1 is provided with a tubular housing 4 in the form of a trocar which is inserted into a pregnant woman 6 for obtaining a view of the presenting part 8 of the foetus. Unless a breech birth is concerned, the presenting part involves the head of the foetus. Via the trocar, all operations are carried out for taking a blood sample. These actions consist of cleaning the head with the aid of swabs for preventing the amniotic fluid and blood of the mother from mixing with the blood sample to be collected.

Then, optionally, the head is moisturized with a spray for promoting vascular stasis, whereupon an incision is made in the presenting part of the foetus with the aid of a small knife which is slid into the trocar so as to reach the head. For preventing COg from diffusing with the blood, an increased surface tension is created with the aid of vaseline. Then, the blood is removed via a long thin tube 10, by means of the capillary action of the tube 10 or by suction with the mouth.1,1. Eventually, the physician 12 will fill an analysis tube with blood whereupon the blood can be analyzed in the laboratory. The device can further bo provided with a light source 14. Therefore, the known trocar itself does not contain means for making the incision and thereupon measuring the pH-value of the blood sample.

In Fig. 2a, with reference numeral 16, a first embodiment of a device according to the invention is indicated. The device 16 is provided with a tubular housing 18 which, completely analogously to what has been described in relation to Fig. 1, is arranged to be inserted, in use, into a pregnant woman as far as a presenting part of the foetus. The tubular housing is provided with a First free extremity 20 which, in use, abuts against the presenting part of the foetus. The tubular housing 18 is further provided, opposite the first free extremity, with a second free extremity 22, having an open end 23, closed off by a flange 24. Further, the tubular housing is provided at its first free extremity 20 with access means 25, in this example in the form of a small knife 25, for obtaining access to body fluid, such as blood or interstitial fluid, of the foetus whose reserves are to be determined. In this example, the small knife 25 is provided with two sharp cutting edges 26,28, directed at least virtually perpendicularly relative to eaeh other, for making an incision. The small knife 25 itself has the shape of a channel 30 with a V-shaped cross section in a plane parallel to the plane defined by the edges 26, 28. Further, in the channel 30, a contact-pH-sensor 32 and/or a contact-lactate-sensor 34 are/is included, which are each of a type known per se (see Fig. 2b).

The small knife 25 is connected to an operating element in the form of an operating rod 36 reaching from the small knife 25 in the longitudinal direction of the tubular housing 18, through an opening 40 of the flange 24 beyond the tubular housing 18. Further, in the tubular housing, an inner tube 42 and a middle tube 44 ate included, the inner tube 42 extending substantially in the middle tube 44 and the middle tube 44 extending substantially within the tubular housing, the arrangement being such that the middle tube, inner tube and tubular housing are arranged co-axially relative to each other. The operating rod 36 is included in the inner tube so as to be slideable in its longitudinal direction over a hmited path. The operating rod 36 is provided with sealing rings 46, 46¹ which can move along an inner side of the inner tube in the longitudinal direction of the inner tube over the limited path mentioned, forming an airtight sealing between the inner tube 42 and the operating rod 36. At its inside, the inner tube 42 is further provided with a first and second projection 48, 50 between which one of the sealing rings 46, 46¹ is located, while this sealing 46, 46¹ can move freely between the two projections 48, 50 for defining a limited path along which the operating rod 36 and hence the small knife 25 are moveable for carrying out a controlled incision. The contact-pH-sensor is connected to an electric signal line 51a reaching through the operating 36 beyond the tubular housing, to be connected to a measuring unit 53 provided with a display 55, Also, the contact-lactate- sensor is connected to an electric signal line 51a reaching through the operating rod 36 outside the tubular housing to be connected to the measuring unit 53. The space 52a, 52b extending between the inner tube 42 and the middle tube 44 is divided by a partition 54 into two channels 52a, 52b separated from each other, each having the shape of a half cylinder. At the second free extremity 22, the first channel 52a is in fluid communication with a hose 56 and at the secon free extremity 22, the second channel 52b is in fluid communication with a hose 58. Via the openings and the first free extremity 20 (second free extremity 22) of the tubular housing 18 the hoses reach into the flange 24 beyond the tubular housing 18. At the free extremity of the inner tube 42 at the first free extremity of the tubular housing 18, a camera 60 is mounted. A signal line 62 reaches from the camera 60 through the inner tube in the direction of the second free extremity 22 through an opening in the flange 24 beyond the tubular housing 18. In this example, the signal line 62 is also connected to the measuring unit 53.

The middle tube 44 is partly of double-walled design. This double- walled part encloses a space 64 open at the free extremity of the middle tube 44 located in the tubular housing 18 adjacent the second free extremity 22. In the cylindrical space 64, an annular plunger 66 is included which, by means of an operating device 68 reaching out through the flange 24, can be reciprocated in the longitudinal direction of the tubular housing 18, It is noted that the flange 24 is provided with various seaϋngs, cooperating with the operating device 68, the hoses 56, 58, the operating rod 36 and the signal line 62 for sealing off the free extremity of the tubular housing in an at least substantially airtight manner. Finally, it is noted that the free extremity 70 of the inner tube 42 is of a somewhat flexible design.

The operation of the device described so far is as follows. The tubular housing 18 is inserted into the pregnant woman as described with reference to Fig. 1. As a result, the first free extremity 20 of the tubular housing comes to abut against the presenting part of the foetus. Then, the operating device 68 is moved in the tubular housing 18 in the direction of the foetus so that the plunger 66 moves away from the flange 24. The result is that in the space 71 extending between the tubular housing and the middle tube a vacuum is created. This, in turn, results in the flexible first free extremity 20 of the tubular housing and the flexible free extremity 70 of the inner tube 42 being drawn against the presenting part. In particular as the free extremity 70 and the first free extremity 20 are of flexible design, a good sealing is obtained with the presenting part of the foetus. Basically, therefore, the tubular housing 18 is provided at its first free extremity 20 with a vacuum element for fixing this free extremity, in use, by means of a reduced pressure, against the presenting part of the foetus. This vacuum element is provided with flexible suction mouths in the form of the flexible free extremities 20, 70.

After the free extremity 20 of the tubular housing IS is thus, by means of a reduced pressiire, fixed against the presenting part of the foetus, air is supplied to the hose 58. Simultaneously, air is drawn away via the hose 56. The result is that the area of the presenting part enclosed by the free extremity 70 of the ^"inner^" tube is cleaned. The air nica is blown into the hose 58 dries the respective area while impurities are sucked away via the hose 56. Thus, the tubular housing is provided with a cleaning means for cleaning the presenting part of the foetus prior to the incision being made. The cleaning means are provided with the first channel 52b extending through the tubular housing, with an open extremity at the free extremity of the housing, for supply of the cleaning air to the presenting part of the foetus and the second channel 52a extending through the tubular housing with an open extremity at the free extremity of the tubular housing for sucking away impurities at the presenting part of the foetus.

After the area has been thus cleaned, the incision can be made. To this end, the operating rod 36 is then moved inwards along the predetermined path until the respective sealing 46 abuts against the second projection 50. As a result, a very precise incision will be made in the presenting part. The blood sample, released as a result, is collected in the channel 30 and hence comes into contact with the pH-sensor 32 and the lactate-sensor 34. The sensors 32, 34 each generate electric signals which, via the signal lines 51a, 51b, are supplied to the measuring unit 53. The measuring unit 53 is provided with a measuring circuit known per se and then directly displays the measured pH-value and/or the measured lactate-value of the blood on the display 55. On the basis of the pH-value anαVor the lactate- value, the expert can properly assess the foetal reserves of the foetus.

During the entire treatment, with the aid of the camera 70, the foetus can be monitored on the display 50.

In Figs. 3a-3c, a second embodiment of the device according to the invention is shown. Here, parts of Figs. 2a-2c corresponding to parts of Figs. 3a-3c are provided with the same reference numerals. In the device according to Figs. 3a-3c, the small knife 25 is of needle-shaped design. On an inside of the middle tube 42, a chamber 80 is included which, at the free extremity 20, is in open communication with an environment of the tubular housing for collecting the blood sample. In the chamber 80, the pH-sensor 32 and/or the lactate-sensor 34 are included, so that at least a part of a pH-seasitive and laetate-sensitive surface, respectively, of the pH-sensor and the lactate-sensor are included in the chamber 80. Further, the operation is completely identical to the one described with reference to Figs. 2a- c. When, with the aid of the small knife 25, an incision is made, the blood which is released or at least a portion thereof will end up in the chamber 80 and there make contact with the sensors 32 and or 34 for determining the pH-value and/or the lactate-value.

With reference to Figs. 4a-4c, a third embodiment according to the invention is described. Here, parts corresponding with those of Figs. 2a-2c are provided with the same reference numerals as in the Figs. 2a-2c.

In the device according to Fig. 4a, the operating rod 36 is fixedly connected to the inner tube 42 while, moreover, the edges 26 and 28 are not designed as cutting edges. Thus, the operating rod 36 is, in fact, no longer an operating rod 36 because the rod 36 is fixedly arranged. Moreover, the edges 26 and 28 do not constitute cutting edges so that the device is not provided with access means 25 in the form of a small knife. In this example, the access means 25 comprise a vacuum element formed by the hoses 56, 58 and the channels 52a and 52b. The operation of the device is as follows.

First, the device is inserted and fixed with the aid of operating device 68 as discussed hereinabove. Thereupon, cleaning takes place by supplying air to the duet 58 and withdrawing air from the duct 56 as discussed hereinabove. Then, in both ducts 56, 58 a vacuum is created. The result is that the free extremity 70 of the inner tube then functions as a suction mouth of a vacuum element which,'^' as a result of the reduced pressure within the inner tube 42, is drawn against, the presenting part of the foetus. In an opening 75 of the inner -tube, 42 at the .free extremity 70, a low reduced pressure is created. Tho thuβ created vacuum is large to such an extent, that interstitial body fluid is withdrawn from the presenting part of the foetus. This body fluid is collected in the channel 30 and there comes into contact with the pH-sensor 32 and/or the lactate-sensor 34 for determining the pH-value and/or the laetate-yalue as discussed hereinabove.

With reference to Pigs. 5a-5c, a fourth embodiment of the device according to the invention will be discussed, while the corresponding parts of Figs. 2a- 2c and Figs. 5a-5c are provided with the same reference numerals. In this variant, the access means consist of a fiber which on an outside thereof is at least partly covered with a pH-and/or lactate-sensitive coating 82, forming a sensor surface of a sensor. The coating 82 is connected to the above-mentioned signal lines 51a, 51b, such that the signal line 51a is connected to the pH- sensitive coating and the sign l line 51b is connected to the lactate-sensitive coating. The coatings consist of coatings known per se, With the pH-sensitive coating, for instance by means of a fluorescence, a measurement is obtained. Inserting, fixing and cleaning is carried out as discussed with reference to Figs. 2a - 2c, Then, with the aid of the operating element 36, at the free extremity of the tubular housing, the free extremity of the fiber is moved out of the tubular housing for penetrating the presenting part of the foetus so that in the foetus, body fluid can come into contact with the relevant coating, whereupon the measurement can take place.

Preferably, the pH-sensitive coating comprises a pH-sensitive mixture of a metallic organic fluorescent substance and a hydrophobic polymer. With this device also, by creating a vacuum in the space 71, the instrument can be fixed. Also, in the space 75 a vacuum can be created by creating a vacuum in the hoses 56, 58. As a result, a larger puncture area is obtained between the top layer of the skin and the skull in that the skin will be pulled off the skull to some extent. This vacuum can also provide for more interstitial fluid. This can promote moisturizing of the sensor. The thus formed vacuum element will move the skin away the skull exactly at the location of penetration of the fiber 25.

The invention is not limited in any manner to the embodiments outlined hereinabove. For instance, the pH-sensor in the device according to Figs. 2, 3 and 4, an ISFET (Ion Selective Field Effect Transistor) can be provided. However, different types of contact-pH-sensors are also possible. In the above-described exemplary embodiments, the electric measuring circuit is included in the separate measuring unit 53, which also displays the video images of the camera 60. However, it is also possible for the electric measuring circuit proper to be included in the tubular housinglS while the tubular housing is provided at its outside with a display for direct display of the measured pH- and/or lact te-values. Further, either the lactate-sensor or the pH-sensor can be omitted so that only one type of measurement (pH-value or lactate-value) can be carried out. Further, the entire device can be designed as a disposable article. Such variants are all understood to fall within the scope of the invention.

Claims

1. A device for determining foetal reserves of a foetus during childbirth, provided with a tubular housing which is arranged to be inserted, during use, into a vagina of a pregnant woman as far as a presenting part (generally a head) of the foetus, characterized in that the tubular housing at a first free extremity of the tubular housing is provided with access means for obtaining access to body fluid, such as blood or interstitial fluid, of the foetus whose reserves are to be determined and that the tubular housing is further provided with at least one contact-pH-sensor and/or one lactate-sensor for. measuring, by means of contact between the body fluid and the pH-sensor and/or the lactate-sensor, the pH-value and/or the lactate-value, respectively, of the body fluid to which access has been obtained with the aid of the access means.

2. A device according to claim 1, characterized in that the access means are provided with a small knife for performing an incision on the presenting part of the foetus for obtaining blood from the foetus, the pH-sensor and/or the lactate-sensor being positioned such that the blood obtained from the foetus comes into contact with the pH-aensor and/or the lactate-sensor.

3. A device according to claim 2, characterized in that the small knife is connected to the tubular housing so as to be movable over a limited path for performing a controlled incision,

4. A device according to claim 3, characterized in that the tubular housing is further provided with an operating member for moving the small knife relative to the tubular housing for making the incision.

5. A device according to claim 2, 3 or 4, characterized in that in the tubular housing, a chamber is included which at the first free extremity is in open communication with an environment of the tubular housing for collecting the blood while at least a part of a surface of the pH-sensor and/or the lactate- sensor is included in the chamber.

6. A device according to any one of claims 2 - 5, characterized in that the tubular housing at the first free extremity is further provided with a vacuum element for fixing the first free extremity, in use, by means of a reduced pressure, against the presenting part of the foetus.

7. A device according to claim 6, characterized in that the vacuum element is provided with at least one flexible suction mouth.

8. A device according to any one of preceding claims 2 — 7, characterized in that the tubular housing is further provided with cleaning means for cleaning the presenting part of the foetus before the incision is ■ made.

9. A device according to claim 8, characterized in that the cleaning means are provided with a first channel extending through the tubular housing, with an open end at the first free extremity of the housing for supplying cleaning air to the presenting part of the foetus, and a second channel extending through the tubular housing with an open end at the first free extremity of the tubular housing for sucking away impurities at the presenting part of the foetus. 10. A device according to claim 1, characterized in that at the first free extremity, the tubular housing is further provided with a vacuum element for fixing the first free extremity, in use, by means of a reduced pressure, against the presenting part of the foetus and withdrawing, by means of the reduced pressure, interstitial body fluid from the presenting part of the foetus, the pH- sensor and/or the lactate-sensor being positioned such that the interstitial fluid obtained from the foetus comes into contact with the pH-sensor and/or the lactate-sensor. . _ A device according to claim 6, characterized in that the vacuum element is provided with at least one flexible suction mouth.

12. A device according to any one of the preceding claims, characterized in that the pH-sensor is provided with an ISFET (Ion Selective Field Effect Transistor).

13. A device according to claim 1, characterized in that the access means and the pH-sensor and/or the lactate-sensor comprise a fiber which on the outside of the fiber is covered at least partly with a pH- and/or lactate- sensitive coating forming a sensor surface of the sensor, the device being arranged for moving, at th first free extremity of the tubular housing, a free extremity of the fiber outside of the tubular housing for penetration into the presenting part of the foetus so that in the foetus, body fluid comes into contact with the coating.

14. A device according to claim 13, characterized in that the fiber is provided in the tubular housing while the tubular housing at the first free extremity is provided with an opening through which, in use, the free extremity of the fiber can be moved out for carrying out the penetration.

15. A device according to claim 14, characterized in that the fiber is connected to the tubular housing so as to be moveable over a limited path for controlled penetration with the fiber into the presenting part of the foetus.

16. A device according to claims 14 or 15, characterized in that the tubular housing is further provided with an operating member for moving the fiber relative to the tubul housing at penetration.

17. A device according to any one of claims 13 - 16, characterized in that the tubular housing at its first free extremity is further provided with a vacuum element for fixing the free extremity, in use, by means of a reduced pressure, against the presenting part.

18. A device according to claim 17, characterized in that the vacuum elemenfcjs provided with at least one flexible suction mouth.

19. _ A device according to any one of preceding claims 13 — 18, characterized in that the coating comprises a pH-sonsitive mixture of a metallic organic fluorescent substance and a hydrophobic polymer.

20. A device according to any one of the preceding claims, characterized in that the tubular housing at the first free extremity is further provided with a video camera for, in use, observing the foetus.

21. A device according to any one of the preceding claims, characterized in that the tubular housing is designed as a disposable article.

22. A device according to any one of the preceding claims, characterized in that in the tubular housing an electric circuit is included which is connected to the pH-sensor and/or the lactate-sensor while on an outside of the housing a display connected to the electric circuit is provided for displaying the measured pH-value and/or lactate-value.

23. A device according to any one of preceding claims 1 — 21, characterized in that the device is further provided with a computer which, in use, is connected to the sensor for determining the pH-value or the lactate- value. 24. A device according to any one of the preceding claims, characterised in that the tubular housing is provided with a second free extremity located opposite the first free extremity, which forms a handle for the user.