GB2126100A

GB2126100A - Uterine sampling device

Info

Publication number: GB2126100A
Application number: GB08323013A
Authority: GB
Inventors: Clare Bernadette Modell; Richard Humphry Thomas Ward
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-09-08
Filing date: 1983-08-26
Publication date: 1984-03-21
Also published as: GB8323013D0; GB2126100B

Abstract

A uterine sampling instrument has an outer flexible tube 1 and a bendable stylet 20 that is insertable within the outer tube. The length (1) of the outer tube 1 is about 193 mm, the stylet having a rounded tip 22 which projects from the forward, tapered end 3 of the outer tube by about 1 mm. A stop 10 of resilient material is slideable along the outer tube. At its rear end, the outer tube 1 has a hub 5 which can be engaged by a syringe. The stylet 20 also has a hub 24 at its rear end which has a finger grip 26 projecting from one side. In use, the stop 10 is positioned to prevent penetration of the epiblast of the patient, and the forward end 3 of the instrument is inserted through the cervix. Chorionic villi are dislodged from the epiblast by the forward end of the instrument, and the stylet 20 is then removed. The syringe is attached to the hub 5 and suction applied to withdraw chorionic villi for analysis. <IMAGE>

Description

SPECIFICATION Uterine sampling instruments and methods This invention relates to uterine sampling instruments and methods.

The invention is more particularly concerned with instruments and methods for obtaining samples of chorionic villi or trophoblast from pregnant women.

Antenatal diagnosis of hereditary disease normally involves analysis of either amniotic fluid (liquor or cells) or foetal blood obtained between the sixteenth and nineteenth week of pregnancy.

Because of the time taken to perform the analysis, an affected pregnancy often cannot be terminated until the gestational age of the foetus is twenty to twenty-two weeks.

For some diseases, however, it is possible to perform the diagnosis at a much earlier date, such as, after the eighth week of pregnancy, by analysis of the chorionic villi. In addition to the advantage realised by the early results, there is the advantage that samples of chorionic villi can, by use of the present invention, be obtained with less trauma and risk of damage to the foetus.

It is an object of the present invention to provide a sampling instrument and method that can be used to obtain chorionic villi.

According to one aspect of the present invention there is provided a uterine sampling instrument including a flexible outer tube that is open at both ends, a bendable stylet that is insertable within the outer tube, and a movable stop member that is slidable along the outer tube, the length of the outer tube being such that the forward end of the instrument can be inserted through the cervix of a patient and such that chorionic villi can be withdrawn through the outer tube by suction.

The outer tube may have a hub at its rear end, the instrument including a syringe that is engageable with the hub so that chorionic villi can be withdrawn through the outer tube by suction applied by the syringe. The stylet may project from the outer tube at the forward end of the instrument when the stylet is inserted within the outer tube, and the stylet may project from the outer tube by about 1 mm. The forward end of the stylet may have a rounded tip, and the forward end of the outer tube may be tapered. The length (1) of the outer tube may be between about 150 mm and 200 mm and may be substantially 193 mm. The stop member may be of a resilient material. The rear end of the stylet may be provided with a finger grip on one side of the stylet.

According to another aspect of the present invention there is provided a method of obtaining a sample from a patient including the steps of: providing a uterine sampling instrument having a flexible outer tube that is open at both ends, a bendable stylet that is insertable within the outer tube, and a movable stop member that is slidable along the outer tube; inserting the stylet within the outer tube; positioning the stop member to prevent penetration of the epiblast of the patient; inserting the forward end of the instrument through the cervix of the patient, dislodging chorionic villi from the epiblast with the forward end of the instrument; removing the stylet; and applying suction to the rear end of the outer tube so as to withdraw chorionic villi.

Suction may be applied by connecting a syringe to the rear end of the outer tube.

A uterine sampling cannula assembly, and its method of use, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a sectional side elevation of the cannula assembly; Figure 2 shows one end of the cannula to a larger scale; Figure 3 is a transverse section of the cannula assembly on the line Il-Il; Figure 4 shows a part of an alternative cannula to a larger scale; and Figures 5 and 6 illustrate the use of the cannula assembly.

With reference to Figures 1 to 3, the cannula assembly includes an outer tube 1 of flexible plastics material that has a length (1) of 193 mm and an internal diameter of 1.0 mm. Distance maricings (not shown) may be provided along the outer tube 1. The bore 2 of the tube 1 is open at its forward end 3, and is tapered, as shown in Figure 2, to remove sharp edges. The rear end of the tube is joined with a more rigid plastics hub 5 that is open at its rear end 6 which is provided internally with a female Luer-tapered bore 7. A disc-shape stop 10 of natural rubber is slidable along the tube 1, the stop being 10 mm in diameter. The stop has a central aperture 11 which is a tight fit about the tube.

The assembly also includes a stylet 20 having a substantially rigid but bendable solid stainless steel rod 21 that is 210 mm long (L) and that has a rounded tip 22. The rod 21 is joined at its rear end 23 with a plastics hub 24. The hub 24 is of a generally cylindrical shape, having a forward end 25 of reduced diameter, and a radialiy-extending flange, or finger grip 26 that projects to one side of the hub, about mid-way along its length.

In use, the metal rod 21 of the stylet is inserted within the outer tube 1 to its full extent, so that the forward end 25 of the stylet hub 24 projects within the Luer bore 7 of the other hub 5, and with the tip 22 of the metal rod 21 projecting by about 1 mm from the forward end 3 of the outer tube 1.

The forward end 3 of the outer tube 1 may take an alternative form such as shown in Figure 4. In this embodiment the bore 2 is sealed at the tip of the tube 1 and the tube is formed with a side port 8 in its wall, close to the forward end 3. An X-ray opaque, or ultrasound-reflective marker element, such as a metal slug 9, may be inserted at the tip of the tube so as to enable its location readily to be determined.

The cannula is used to remove samples of chorionic villi or trophoblast in the following manner. The stop 10 is first moved along the tube 1 to the correct position, according to the build of the patient, and the stylet 20 is bent by the surgeon in the required curve. The cannula - with the stylet 20 in position to provide rigidity - is then inserted through the cervix 100 into the uterus 101, as shown in Figure 5. Because the finger grip 26 is located on one side of the stylet, the orientation of the forward end of the stylet can be readily determined when in position. The diameter of the stop 10 is sufficient to prevent its entry into the external os 1 02.The aim of the procedure is to dislodge chorionic villi 104 from the epiblast 103 and this may be done by gently rubbing the tip 3 of the cannula across the epiblast, with the stylet in place. The stylet 20 is then removed and the nose 30 of a syringe 31 is inserted into the rear end 6 of the hub 5 to form a Luer-slip fit in the bore 7, as shown in Figure 6. A sample of chorionic villi is obtained by withdrawing the plunger of the syringe. The sample can then be used for gene analysis and diagnosis of haemoglobinopathies.

The provision of the movable stop on the tube reduces the risk that the cannula will be inserted far enough into the uterus to puncture the epiblast. By providing the stylet with a rounded tip that projects from the forward end of the outer tube 1, the risk of damage to the epiblast is further reduced.

It will be appreciated that various modifications could be made to the cannula assembly and that the dimensions could be altered according to the build of the patient. In general, the cannula would be between 150 and 200 mm long.

Claims

1. A uterine sampling instrument, wherein the instrument includes a flexible outer tube that is open at both ends, a bendable stylet that is insertable within the outer tube, and a movable stop member that is slidable along the outer tube, the length of the outer tube being such that the forward end of the instrument can be inserted through the cervix of a patient and such that chorionic villi can be withdrawn through the outer tube by suction.

2. A uterine sampling instrument according to Claim 1, wherein the outer tube has a hub at its rear end, and wherein the instrument includes a syringe that is engageable with the hub so that chorionic villi can be withdrawn through the outer tube by suction applied by the syringe.

3. A uterine sampling instrument according to Claim 1 or 2, wherein said stylet projects from the outer tube at the forward end of the instrument, when the stylet is inserted within the outer tube.

4. A uterine sampling instrument according to Claim 3, wherein the forward end of said stylet projects from said outer tube by about 1 mm.

5. A uterine sampling instrument according to any one of the preceding claims, wherein the forward end of the stylet has a rounded tip.

6. A uterine sampling instrument according to any one of the preceding claims, wherein the forward end of the outer tube is tapered.

7. A uterine sampling instrument according to any one of the preceding claims, wherein the length (1) of the outer tube is between about 150 mm and 200 mm.

8. A uterine sampling instrument according to Claim 7, wherein the length (1) of the outer tube is substantially 193 mm.

9. A uterine sampling instrument according to any one of the preceding claims, wherein said stop member is of a resilient material.

10. A uterine sampling instrument according to any one of the preceding claims, wherein the rear end of said stylet is provided with a finger grip on one side of the stylet.

11. A uterine sampling instrument substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.

12. A method of obtaining a sample from a patient, including the steps of: providing a uterine sampling instrument having a flexible outer tube that is open at both ends, a bendable stylet that is insertable within the outer tube, and a movable stop member that is slidable along the outer tube; inserting the stylet within the outer tube; positioning the stop member to prevent penetration of the epiblast of the patient: inserting the forward end of the instrument through the cervix of the patient; dislodging chorionic villi from the epiblast with the forward end of the instrument; removing the stylet; and applying suction to the rear end of the outer tube so as to withdraw chorionic villi.

13. A method according to Claim 12, wherein suction is applied by connecting a syringe to the rear end of the outer tube.

14. A method substantially as hereinbefore described with reference to Figures 1 to 4 of the accompanying drawings.

15. Any novel feature or combination of features as hereinbefore described.