Patent Publication Number: US-11648034-B2

Title: Device, instrument and belt for tying cervix

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 16/220,221, filed on Dec. 14, 2018, which itself claims the benefits of Taiwan applications Serial No. 106144244 filed on Dec. 15, 2017, and Serial No. 107142412 filed on Nov. 28, 2018. The disclosures of the above applications are incorporated by references herein in their entireties. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates in general to a device, instrument and belt for tying a cervix, and more particularly to the device, instrument and belt that can be simply structured and easily operated to tie a cervix. 
     BACKGROUND 
     In the art, preterm birth is defined as a delivery prior to a 37-week pregnancy. Currently, in the maternal-fetal medicine, at least two kinds of pregnant women would be entitled in the high risk group of preterm birth. One is a pregnant woman who has a preterm birth history. Another is a pregnant woman whose cervix length is less than 25 mm. To this kind of pregnant women, even though no significant evidence of preterm birth is shown, the possibility thereof is still high. In the medical art, a cervix length measurement is usually introduced to screen specific pregnant women in the risk group of preterm birth. Nevertheless, regarding the aforesaid two kinds of pregnant women in the high risk of preterm birth, especially to those who are patients of cervical insufficiency, current policies against the preterm birth include at least the cervical cerclage and the pessary. The cervical cerclage uses sutures to completely stitch up the cervical orifice of the pregnant woman. On the other hand, the pessary is planted inside the vagina so as hopefully to stabilize the womb by fixing the cervix at a specific angle, such that the fetus can be prevented from descending, from which the cervical orifice would be forced to open earlier and eventually lead to a preterm birth. 
     Clinically, various evidences have proved that the cervical cerclage is effective to those pregnant women, whom are among the high risk group of preterm birth, and whom are patients of cervical insufficiency. However, to perform the cervical cerclage, the pregnant woman shall be anesthetized in advance, and this anesthetic process shall be performed by a qualified surgeon. In addition, since the majority of pregnant women usually concern the risk upon the fetus and the mother herself caused by the anesthetic process, related operations and even the hospitalization, thus the acceptability of the cervical cerclage does stay low. Beside the risk to the pregnant woman and the low acceptability, a braided suture among various sutures required in the surgery is usually concerned for having a minor rough woven surface, which won&#39;t be smoothened out after being tied. However, according to a British report, in a total number of about 700 pregnant women who accepted the cervical cerclage, 28% of the pregnant woman using the braided suture met the preterm birth, and 15% thereof met abortion or stillbirth; while 17% of the pregnant woman using the single-thread nylon suture met the preterm birth, and 5% thereof met abortion or stillbirth. It is highly doubt that one of possible causes accounted for fetus contamination is that the minor rough woven surface of the braided suture failed the sterilization of the operation. 
     On the other hand, regarding the pessary, recent clinical testing has proved that the usage of the pessary does not reduce the occurrence rate of preterm birth for single-fetus pregnancy. 
     Accordingly, if there is a device, instrument and belt for tying a cervix of a pregnant woman that can be immediately applied clinically without a surgery, an anesthetic process and even hospitalization, the acceptability thereof by pregnant women would be significantly increased, and the occurrence rate of the preterm birth would be substantially reduced. Thereupon, such an improvement is definitely urgent to the skill in the art. 
     SUMMARY 
     In one embodiment of this disclosure, a device for tying a cervix includes a belt and an instrument. The belt is used to tie a cervix. The instrument, applied to tie the belt onto the cervix, includes a first outer pipe, a second outer pipe and two fork structures. The second outer pipe is rotatable with respect to the first outer pipe. The two fork structures are connected individually to corresponding axial ends of the first outer pipe and the second outer pipe, respectively, and each of the two fork structures is to be detachably inserted into the belt. 
     In another embodiment of this disclosure, an instrument includes a first outer pipe, a second outer pipe and two fork structures. The second outer pipe is rotatable with respect to the first outer pipe. The two fork structures, connected individually to corresponding axial ends of the first outer pipe and the second outer pipe, respectively, are to be inserted into a belt detachably. 
     In a further embodiment of this disclosure, a belt includes a head portion, a middle portion and a tail portion. The head portion has a head-end plug hole and a head-end through hole. The head-end through hole is furnished thereinside with an inner teeth structure. The tail portion has a tail-end plug hole. The middle portion, located between the head portion and the tail portion, having at least one section thereof with two opposing lateral sides to provide individual outer teeth structures to pair the inner teeth structure, the head-end plug hole and the tail-end plug hole being inserted detachably by two fork structures of an instrument, respectively. 
     Further scope of applicability of the present application will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the disclosure, are given by way of illustration only, since various changes and modifications within the spirit and scope of the disclosure will become apparent to those skilled in the art from this detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure will become more fully understood from the detailed description given herein below and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present disclosure and wherein: 
         FIG.  1    is a schematic perspective view of a device for tying a cervix in accordance with an embodiment of this disclosure; 
         FIG.  2    is a schematic exploded view of an instrument of the device of  FIG.  1   ; 
         FIG.  3    is a schematic cross-sectional view showing different states of the instrument of  FIG.  1   ; 
         FIG.  4    is a schematic perspective view of the instrument for tying a cervix in accordance with another embodiment of this disclosure; 
         FIG.  5    is a schematic exploded view of  FIG.  4   ; 
         FIG.  6    is a schematic cross-sectional view showing different states of the instrument of  FIG.  4   ; 
         FIG.  7    is a schematic perspective view of the instrument for tying a cervix in accordance with a further embodiment of this disclosure; 
         FIG.  8    is a schematic exploded view of  FIG.  7   ; 
         FIG.  9 A  demonstrates schematically the pairing of the second handle and the positioning slot in the instrument of  FIG.  7   ; 
         FIG.  9 B  is a schematic cross-sectional view of the sliding slots and the sliding node in the instrument of  FIG.  7   ; 
         FIGS.  10   ˜ 12  demonstrate schematically different states of the instrument of  FIG.  7   , showing particularly relative positions of the sliding slots and the sliding node; 
         FIG.  13    is a schematic view showing the instrument of  FIG.  7    and a paired lighting device; 
         FIGS.  14 A ˜ 14 B demonstrate angling of the two fork structures in the instrument of  FIG.  7   ; 
         FIGS.  15 A ˜ 15 C are a top view, a front view and a left-side view of a belt of  FIG.  1    in an extended state, respectively; 
         FIGS.  16 A ˜ 16 C are a top view, a front view and a left-side view of a head portion of the belt of  FIG.  1   , respectively; 
         FIG.  17    demonstrates schematically an engagement state between a middle portion and the head portion of the belt of  FIG.  1   ; 
         FIG.  18    demonstrates schematically an adjusted state of the belt of  FIG.  1   ; 
         FIG.  19    is a schematic view showing related rotations between a first outer pipe and a the second outer pipe; 
         FIG.  20    demonstrates forcing of the two fork structures in the instrument of  FIG.  7    upon the belt; 
         FIGS.  21 A ˜ 21 C are a top view, a front view and a left-side view of the belt in accordance with another embodiment of this disclosure, respectively; 
         FIGS.  22 A ˜ 22 C are a top view, a front view and a left-side view of the head portion of the belt of  FIGS.  21 A ˜ 21 C, respectively; 
         FIG.  23    demonstrates schematically an engagement state between the middle portion and the head portion of the belt of  FIGS.  21 A ˜ 21 C; 
         FIGS.  24 A ˜ 24 C are a top view, a front view and a left-side view of the belt in accordance with yet another embodiment of this disclosure, respectively; 
         FIGS.  25 A ˜ 25 F demonstrate different stages of operation of the embodiment of  FIG.  1   ; and 
         FIGS.  26 A ˜ 26 F demonstrate different stages of operation of the embodiment of  FIG.  7   . 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing. 
     Referring now to the embodiment shown in  FIG.  1   , the device for tying a cervix  100  includes a belt  10  and an instrument  20 . The belt  10  for tying the cervix is to forbid a cervical orifice to open. The instrument  20  is to apply and thus tie the belt  10  onto the cervix. The belt  10  can be made of a biocompatible elastic plastics, such that the belt  10  can be left inside a human body without making any specific damage. 
     Referring now to  FIG.  1    through  FIG.  3   , the instrument  20  includes a first outer pipe  21 , a second outer pipe  22 , a first inner pipe  23  and a second inner pipe  24 , in which the first outer pipe  21 , the second outer pipe  22 , the first inner pipe  23  and the second inner pipe  24  are all coaxial. In this embodiment, the first outer pipe  21 , the second outer pipe  22 , the first inner pipe  23  and the second inner pipe  24  are telescoped orderly inwards and rotational to each other. In particular, the first outer pipe  21  can rotate about the second outer pipe  22 . Two fork structures  211 ,  221  are individually connected to corresponding axial ends of the first outer pipe  21  and the second outer pipe  22 , respectively. Free ends of these two fork structures  211 ,  221  are together to handle the belt  10 , through inserting in a detachable manner. An axial end of the first inner pipe  23  connects a claw mechanism  25 . The claw mechanism  25  includes, but not limited to, three claw fingers  251 . The second inner pipe  24 , sleeved axially by the first inner pipe  23 , can move with respect to the second inner pipe  24 . Each inner diameter of the fork structures  211 ,  221  is greater than an outer diameter of the claw mechanism  25 , such that the fork structures  211 ,  221  can move back and forth about the claw mechanism  25  in an axial direction F 1 . 
     Referring now to  FIG.  3   , in each of the claw fingers  251 , a gear  252  is pivotally mounted to an inner side of a root of the claw finger  251 , and a rack  241  to mesh the gear  252  is constructed axially and exteriorly at the axial end of the second inner pipe  24 . Thereupon, the claw mechanism  25  can connect the second inner pipe  24  via meshing the gear  252  and the rack  24 . As the second inner pipe  24  performs an axial moment with respect to the first inner pipe  23 , the rack  241  would rotate the respective gears  252  simultaneously so as to open/close the three claw fingers  251 . 
     Referring now to  FIG.  4    through  FIG.  6   , another embodiment of the instrument according to this disclosure is shown. This instrument  20 A includes a first outer pipe  21 , a second outer pipe  22 , a first inner pipe  23 A and a second inner pipe  24 A. Two fork structures  211 ,  221  are individually connected to corresponding axial ends of the first outer pipe  21  and the second outer pipe  22 , respectively. Free ends of these two fork structures  211 ,  221  are together to handle the belt  10  of  FIG.  1   , through inserting in a detachable manner. In this embodiment, an axial end of the second inner pipe  24 A connects a claw mechanism  25 A. The claw mechanism  25 A includes, but not limited to, three cantilever structures  251 A extending outwards individually from the second inner pipe  24 A. Each of the cantilever structures  251 A is connected to the axial end of the second inner pipe  24 A via a connecting member  252 A, and the connecting member  252 A is extended outward radially from the axial end of the second inner pipe  24 A, such that the claw mechanism  25 A can present an axial diffusion state. The second inner pipe  24 A, axially mounted inside the first inner pipe  23 A, can move axially along the first inner pipe  23 A. 
     Referring now to  FIG.  6   , when the claw mechanism  25 A protrudes out from the first inner pipe  23 A, the three cantilever structures  251 A, pre-stressed together to be stored axially into the first inner pipe  23 A, would expand radially outwards. On the other hand, when the three cantilever structures  251 A are retrieved into the first inner pipe  23 A, the three cantilever structures  251 A would be forced to form a bundle in the first inner pipe  23 A. Namely, as the second inner pipe  24 A slides axially with respect to the first inner pipe  23 , the claw mechanism  25 A would perform open or close accordingly via expanding or bundling these three cantilever structures  251 A. 
     Referring now to  FIG.  7    and  FIG.  8   , in this embodiment, the instrument  20 B includes a first outer pipe  21 B, a second outer pipe  22 B, a first inner pipe  23 B and a second inner pipe  24 B. The two fork structures  211 B,  221 B are individually connected to corresponding axial ends of the first outer pipe  21 B and the second outer pipe  22 B, respectively. The fork structures  211 B,  221 B can plug into the belt  20  of  FIG.  1    in a detachable manner. An axial end of the second inner pipe  24 B is connected with a claw mechanism  25 B. The claw mechanism  25 B includes four cantilever structures  251 B extended outward from the second inner pipe  24 B, each of the cantilever structures  251 B is connected to the axial end of the second inner pipe  24 B via a connecting member  252 B, and the connecting member  252 B is extended outward radially from the axial end of the second inner pipe  24 B, such that the claw mechanism  25 B can present an axial diffusion state. In this disclosure, it shall be understood that the number of the cantilever structures  251 B is not strictly limited to be four. The second inner pipe  24 B, axially mounted inside the first inner pipe  23 B, can move axially along the first inner pipe  23 B. 
     It can be seen that the embodiment shown in  FIGS.  7   ˜ 8  is basically an improvement of that shown in  FIGS.  4   ˜ 6 . In particularly, this embodiment of  FIGS.  7   ˜ 8  is further furnished with mechanisms for limiting relative movements among pipes and some other auxiliary structures, so as thereby to enable a simpler operation. 
     Referring now to  FIG.  7    and  FIG.  8   , the first outer pipe  21 B is furnished with a first handle  212 B, and a step ring  226 B is constructed fixedly to an outer surface of the second outer pipe  22 B. Thereupon, the first outer pipe  21 B is mounted between the step ring  226 B and the fork structure  221 B of the second outer pipe  22 B, such that the axial movement of the first outer pipe  21 B can be limited but the rotational movement thereof is allowed. 
     Referring now to  FIG.  7    through  FIG.  9 A , the second outer pipe  22 B has a positioning slot  222 B located at another axial end thereof opposite to the axial end having the fork structure  221 B. The positioning slot  222 B extends axially along the second outer pipe  22 B by a predetermined length to connect spatially a round hole  223 B. The second outer pipe  22 B further has a pair of axial slits  224 B to sandwich the positioning slot  222 B lengthwise. In addition, the first inner pipe  23 B is furnished with a second handle  231 B. 
     Referring to  FIG.  9 A , a width of the positioning slot  222 B is less than an outer diameter of the second handle  231 B, and a diameter of the round hole  223 B is equal to or larger than the outer diameter of the second handle  231 B. With the first inner pipe  23 B to be telescoped inside the second outer pipe  22 B, while the second handle  231 B is moved axially to enter the positioning slot  222 B, the positioning slot  222 B would be enlarged to accommodate the second handle  231 B due to the arrangement of the pairing slits  224 B, and thus the second handle  231 B can move all the way along the positioning slot  222 B to the round hole  223 B. After the second handle  231 B reaches the round hole  223 B, the positioning slot  222 B would resume its original dimensions to restrict the second handle  231 B in the round hole  223 B. 
     Referring to  FIG.  8    and  FIG.  9 B , the second outer pipe  22 B is furnished with a second-outer-pipe sliding slot  225 B to extend axially along the second outer pipe  22 B by a predetermined length, the first inner pipe  23 B is furnished with a first-inner-pipe sliding slot  232 B to extend axially along the first inner pipe  23 B by another predetermined length, and the second inner pipe  24 B is furnished with a sliding node  241 B. 
     By telescoping orderly the first outer pipe  21 B, the second outer pipe  22 B, the first inner pipe  23 B, and the second inner pipe  24 B, the second-outer-pipe sliding slot  225 B would be located at a position in correspondence with the first-inner-pipe sliding slot  232 B, with the sliding node  241 B to be restrained inside both the second-outer-pipe sliding slot  225 B and the first-inner-pipe sliding slot  232 B. In particular, a top of the sliding node  241 B would not contact an inner wall of the first outer pipe  21 B, so that, while the second inner pipe  24 B undergoes an axial movement, the sliding node  241 B can slide smoothly along both the second-outer-pipe sliding slot  225 B and the first-inner-pipe sliding slot  232 B, without being interfered by the inner wall of the first outer pipe  21 B. Namely, the top of the sliding node  241 B and the inner wall of the first outer pipe  21 B are paired in a non-interference manner. In addition, an outer diameter of the sliding node  241 B is less than both a width of the second-outer-pipe sliding slot  225 B and that of the first-inner-pipe sliding slot  232 B, such that the sliding node  241 B can slide smoothly along both the second-outer-pipe sliding slot  225 B and the first-inner-pipe sliding slot  232 B without any interference. Upon the arrangement of the sliding node  241 B, the second-outer-pipe sliding slot  225 B and the first-inner-pipe sliding slot  232 B, relative rotations among the second outer pipe  22 B, the first inner pipe  23 B and the second inner pipe  24 B are prohibited. 
     Referring now to  FIG.  10    through  FIG.  12   , relative positioning of the second-outer-pipe sliding slot  225 B, the first-inner-pipe sliding slot  232 B and the sliding node  241 B in different states of the instrument  20 B are demonstrated. 
     As shown in  FIG.  10   , the first inner pipe  23 B is pushed to stop axially toward the claw mechanism  25 B till the claw mechanism  25 B reaches a close state. At the same time, the first outer pipe  21 B and the second outer pipe  22 B are moved simultaneously toward the end having a grip  242 B, so that the second handle  231 B can be buckled inside the round hole  223 B, the sliding node  241 B can reach an end of the second-outer-pipe sliding slot  225 B adjacent to the fork structure  221 B, and also the sliding node  241 B can reach an end of the first-inner-pipe sliding slot  232 B adjacent to the second handle  231 B. 
     As shown in  FIG.  11   , the first inner pipe  23 B is pulled away from the claw mechanism  25 B, so that, as the second handle  231 B has been retrieved from the positioning slot  222 B and the round hole  223 B, the sliding node  241 B reaches the end of the second-outer-pipe sliding slot  225 B adjacent to the fork structure  221 B, and also the sliding node  241 B reaches an end of the first-inner-pipe sliding slot  232 B away from the second handle  231 B. 
     As shown in  FIG.  12   , the first inner pipe  23 B is pushed to stop toward the claw mechanism  25 B, and then the first outer pipe  21 B and second outer pipe  22 B are both pushed to stop toward the claw mechanism  25 B as well, such that the sliding node  241 B reaches an end of the second-outer-pipe sliding slot  225 B away from the fork structures  221 B, and also the sliding node  241 B reaches the end of the first-inner-pipe sliding slot  232 B adjacent to the second handle  231 B. 
     Referring now to  FIG.  7   ,  FIG.  8    and  FIG.  13   , a hand grip  242 B is furnished to another axial end of the second inner pipe  24 B away from the claw mechanism  25 B. The hand grip  242 B convenient for an user to operate the instrument  20 B has a central through hole  243 B axially establishing a spatial connection between the interior of the second inner pipe  24 B and that of hand grip  242 B. A lighting device  26 , able to be plugged into an free end of the central through hole  243 B away from the second inner pipe  24 B, can provide illumination to the axial end of the second inner pipe  24 B adjacent to the claw mechanism  25 B. The lighting device  26  is not limited to any specific type or configuration. For example, the lighting device  26  can be an elongated light source  261  detachably connected with a control box  262 . The control box  262  is to energize and control the light source  261 . The light source  261  can be ready to use and disposable for one-time usage, while the control box  262  can be reused. In addition, the light source  261  can be an optical fiber or a light-guide rod. The hand grip  242 B, the central through hole  243 B and the lighting device  26  herein can be also applied to the instruments  20 ,  20 A of  FIG.  1    and  FIG.  4   , respectively. In the situation without the hand grip  242 B and the central through hole  243 B, the lighting device  26  can be plugged into the axial end of the second inner pipe  24 B away from the claw mechanism  25 B. In other words, while being applied to any of the instruments  20 ,  20 A of  FIG.  1    and  FIG.  4   , the lighting device  26  can be plugged from the axial end of the second inner pipe  24  or  24 A away from the claw mechanism  25  or  25 A, respectively. Preferably, while being plugged into the second inner pipe from the axial end of the second inner pipe away from the claw mechanism, the lighting device  26  can reach another axial end of the second inner pipe adjacent to the claw mechanism. 
     Referring now to  FIGS.  14 A and  14 B , a first angle θ 1  is formed by a lateral edge of the fork structure  211 B of the first outer pipe  21 B with respect to the axial direction of the first outer pipe  21 B, and a second angle θ 2  is formed by a lateral edge of the fork structure  221 B of the second outer pipe  22 B with respect to the axial direction of the second outer pipe  22 B. As shown, the first angle θ 1  and the second angle θ 2  are leaned to different sides of the axial direction, and each of the first angle θ 1  and the second angle θ 2  is within a range of 1˜45 degrees. Details about the fork structures  211 B,  221 B having oblique edges would be elucidated as follows. 
     Though different structuring of the claw mechanisms  25 ,  25 A,  25 B are shown in  FIGS.  1   ˜ 3 ,  FIGS.  4   ˜ 6  and  FIGS.  7   ˜ 8 , respectively, yet the performances thereof are the same, all of which are achieved by sliding axially the first inner pipes  23 ,  23 A,  23 B with respect to the second inner pipes  24 ,  24 A,  24 B, respectively. Except for the pair of the gear  252  and the rack  241  in  FIG.  3   , in some other embodiments, a cam pair having an eccentric cam and a push rod or the like mechanism can also be applied to control the open/close of the claw mechanism. 
     Referring now to  FIGS.  15 A ˜ 15 C,  FIGS.  16 A ˜ 16 C,  FIG.  17    and  FIG.  18   , the belt  10  includes a head portion  11 , a tail portion  12  and a middle portion  13 . The head portion  11  has a head-end plug hole  111  and a head-end through hole  112 . The head-end through hole  112  has an inner teeth structures  113 ,  114 . The tail portion  12  has a tail-end plug hole  121 . The middle portion  13 , located between the head portion  11  and the tail portion  12 , has at least one section with two opposing lateral sides to provide individual outer teeth structures  131 ,  132  to pair the inner teeth structures  113 ,  114 , respectively. As shown in  FIG.  15 A , an elastic structure  133  is constructed at the belt  10  at a place between the two outer teeth structures  131 ,  132  of the middle portion  13 . In this embodiment, the elastic structure  133  is a hollowed-out section in the middle portion  13  between the two outer teeth structures  131 ,  132  to provide a compressible room while the two outer teeth structures  131 ,  132  are compressed inwards. Upon such an arrangement, the resistance against pulling the middle portion  13  through the head portion  11  (i.e., in a tying direction of the belt  10 ) would be substantially reduced. In addition, the belt  10  further includes a plurality of bumps  14  on a surface thereof between the head portion  11  and the middle portion  13 . In this embodiment, one of the bumps  14  is disposed on, but not limited to, the head portion  11 . While in tying the belt  10 , the tail portion  12  is sent to pierce the head-end through hole  112  of the head portion  11 , with both the outer teeth structures  131 ,  132  of the middle portion  13  to engage the corresponding inner teeth structures  113 ,  114 , as shown in  FIG.  17   . Thereby, the belt  10  can be in a state of an adjustable ring shown in  FIG.  18   , with the plurality of bumps  14  disposed at an inner side of the adjustable ring. 
     Referring now to  FIG.  1    and  FIG.  18   , the two fork structures  211 ,  221  of the instrument  20  are sent to pierce the tail-end plug hole  121  and the head-end plug hole  111  of the belt  10 , respectively. Then, with the second outer pipe  22  stationary, turn the first outer pipe  21  so as to have the fork structure  211  to move the tail portion  12  in a direction to shrink the inner diameter of the belt  10 . In this step, an operator, a surgeon for example, can hold the second outer pipe  22  at one hand, and use another hand to rotate the first outer pipe  21 , such that the tail portion  12  can be driven to decrease the inner diameter of the belt  10 . Similarly, as shown in  FIG.  4    through  FIG.  6   , the aforesaid manipulation can be applied for the instrument  20 A to reduce the inner diameter of the belt  10 . 
     In addition, referring now to  FIG.  1    and  FIG.  19   , at least one constraint structure can be constructed to the first outer pipe  21  and the second outer pipe  22  so as to limit the relative rotatable angle between the first outer pipe  21  and the second outer pipe  22 . For example, a stop node  222  can be constructed at the second outer pipe  22 , while a slot  212  corresponding to the stop node  222  is produced at the first outer pipe  21 . Thereupon, the rotation angle θ 3  of the first outer pipe  21  can be limited. However, it shall be understood that the magnitude of the rotation angle θ 3  depends on practical needs, which can be any angle less than 360 degrees. 
     Referring now to  FIG.  7   ,  FIG.  14 A ,  FIG.  14 B ,  FIG.  18    and  FIG.  20   , the two fork structures  211 B,  221 B of the first outer pipe  21 B and the second outer pipe  22 B of the instrument  20  in  FIG.  7    are sent to pierce the tail-end plug hole  121  and the head-end plug hole  111  of the belt  10 , respectively. Then, with the second outer pipe  22 B stationary, turn the first outer pipe  21 B. Since the first angle θ 1  is formed by the lateral edge of the fork structure  211 B of the first outer pipe  21 B with respect to the axial direction of the first outer pipe  21 B, the second angle θ 2  is formed by the lateral edge of the fork structure  221 B of the second outer pipe  22 B with respect to the axial direction of the second outer pipe  22 B, and the first angle θ 1  and the second angle θ 2  are leaned to different sides of the axial direction; thus the two fork structures  211 B,  221 B can apply opposite out-tension forces F 1 , F 2  to the tail portion  12  and the head portion  11 , respectively. Thereupon, while in rotating the first outer pipe  21 B to shrink the bigger diameter of the belt  10 , the belt  10  can be kept contact with the first outer pipe  21 B and the second outer pipe  22 B. More specifically, during the process for the belt  10  to tighten the cervix, the plug holes  121 ,  111  of the belt  10  can kept holding the corresponding fork structures  211 B,  221 B of the first outer pipe  21 B and the second outer pipe  22 B, respectively. 
     Referring now to  FIGS.  21 A ˜ 21 C,  FIGS.  22 A ˜ 22 C and  FIG.  23   , the belt  10 A includes a head portion  11 A, a tail portion  12 A and a middle portion  13 A. The head portion  11 A has a head-end plug hole  111 A and a head-end through hole  112 A. The head-end through hole  112 A has an inner teeth structure  113 A. The tail portion  12 A has a tail-end plug hole  121 A. The middle portion  13 A has at least one section with both opposing lateral sides furnished with individual outer teeth structures  131 A,  132 A, in correspondence with the inner teeth structures  113 A,  114 A, respectively. In addition, the belt  10 A further includes a plurality of bumps  14 A protrusive individually on a surface of the middle portion  13 A. Then, lead the tail portion  12 A to pierce the head-end through hole  112 A of the head portion  11 A, by having the opposing outer teeth structures  131 A,  132 A of the middle portion  13 A to engage the corresponding inner teeth structures  113 A,  114 A, as shown in  FIG.  23   . Thereupon, the belt  10 A can be reformed into the adjustable ring as shown in  FIG.  18   . At this stage, the plurality of bumps  14 A are located inside the adjustable ring. As described above, the instrument  20  or  20 A of  FIG.  1    or  FIG.  4   , respectively, can be applied to adjust the belt  10 A. 
     Referring now to  FIGS.  24 A ˜ 24 C, the belt  10 B of this embodiment is derived from the belt  10  of  FIGS.  15 A ˜ 15 C. As shown, the belt  10 B includes a head portion  11 B, a tail portion  12 B and a middle portion  13 B. The head portion  11 B has a head-end plug hole  111 B and a head-end through hole  112 B. The head-end through hole  112 B has an inner teeth structure  113 B,  114 B. The tail portion  12 B has a tail-end plug hole  121 B. The middle portion  13 B has at least one section with both opposing lateral sides furnished with individual outer teeth structures  131 B,  132 B, in correspondence with the inner teeth structures  113 B,  114 B, respectively. Between the two outer teeth structures  131 B,  132 B in the middle portion  13 B, an elastic structure  133 B is disposed. The elastic structure  133 B is formed by a plurality of arc-shaped perforations extending lengthwise to provide a compressible space between the two outer teeth structures  131 B,  132 B, so as thereby to reduce the resistance at the middle portion  13 B while in tensioning the head portion  11 B. In addition, the belt  10 B further includes a plurality of bumps  14 B protrusive individually on a surface of the head portion  11 B and the middle portion  13 B. As shown, in this embodiment, the head portion  11 B has one said bump  14 B. According to this disclosure, it is not necessary to have bumps  14 B in the head portion  12 B. Then, lead the tail portion  12 B to pierce the head-end through hole  112 B of the head portion  11 B, by having the opposing outer teeth structures  131 B,  132 B of the middle portion  13 B to engage the corresponding inner teeth structures  113 B,  114 B, respectively, as shown in  FIG.  17   . Thereupon, the belt  10 B can be reformed into the adjustable ring as shown in  FIG.  18   . At this stage, the plurality of bumps  14 B are located inside the adjustable ring. 
     In this embodiment, other features include that, by locating the head-end plug hole  111 B away from the side of the head portion  11 B having the bumps  14 B, the belt  10 B can properly tighten the cervix without substantial position bias after the fork structure  221 B is retrieved from the head-end plug hole  111 . Similarly, in  FIGS.  15 A ˜ 15 C and  FIGS.  21 A ˜ 21 C, the head-end plug holes  111 ,  111 A of the belts  10 ,  10 A can be relocated to another side of the head portions  11 ,  11 A, respectively. In addition, in this embodiment, a plurality of perforated portions  15 B located between the middle portion  13 B and the head portion  11 B are included to adjust the entire stiffness of the belt  10 B, such that the belt  10  of  FIG.  18    can be kept in a circle shape by waiving possible weakness caused by the elastic structure  133 B. 
     Referring now to  FIGS.  25 A ˜ 25 F, different stages of operation of the embodiment of  FIG.  1    upon a cervix inside a vagina are shown orderly. The operator, an surgeon for example, firstly applies the instrument  20  to the belt  10  by inserting. Then, a duck-billed speculum (not shown in the figure) is used to expand the vagina  90  so as to allow the instrument  20  to place the belt  10  to a place in the vagina  90  by approaching the cervix  91 . 
     Referring now to  FIG.  25 A , one end of the instrument that has the belt is sent into the vagina  90 , and then the second inner pipe  24  is pushed to open the claw mechanism  25  and to contact a periphery of the cervix  91 . 
     Referring now to  FIG.  25 B , the second inner pipe  24  is pulled to close the claw mechanism  25  for clamping at the periphery of the cervix  91 . 
     Referring now to  FIG.  25 C , both the first outer pipe  21  and the second outer pipe  22  are pushed forward so as to have the belt  10  to move toward the cervix  91  and to reach the periphery of the cervix  91  by surpassing the claw mechanism  25 . Then, the first outer pipe  21  is rotated to have the belt  10  to tie the cervix  91  at the periphery thereof. Refer back to  FIG.  18    and the related description for a method to adjust the inner diameter of the belt  10 . By having the bumps  14  to bite the cervix  91 , the fixation of the belt  10  to on the cervix  91  can be further ensured. 
     Referring now to  FIG.  25 D , both the first outer pipe  21  and the second outer pipe  22  are pulled outward so as to separate the first outer pipe  21  and the second outer pipe  22  away from the belt  10 . Then, the belt  10  can sleeve the cervix  91  at the periphery thereof. It should be noted that, at this time, the claw mechanism  25  still clamps the cervix  91  at the periphery thereof. 
     Referring now to  FIG.  25 E , the second inner pipe  24  is pushed to open the claw mechanism  25 , and so the cervix  91  is released from the claw mechanism  25 . 
     Referring now to  FIG.  25 F , the first inner pipe  23  and the second inner pipe  24  are pulled back to be stored into the first outer pipe  21  and the second outer pipe  22 . Then, the entire instrument  20  is retrieved away from the vagina  90 . Upon such an operation, the belt  10  can tie the cervix  91  in a sleeving manner. 
     Referring now to  FIGS.  26 A ˜ 26 F, different stages of operation of the embodiment of  FIG.  7    upon a cervix inside a vagina are shown orderly. The operator, an surgeon for example, firstly applies the instrument  20 B to the belt  10 B by inserting. Then, a duck-billed speculum (not shown in the figure) is used to expand the vagina  90  so as to allow the instrument  20 B to place the belt  10 B to a place in the vagina  90  by approaching the cervix  91 . 
     Referring now to  FIG.  26 A , one end of the instrument  20 B that has the belt  10 B is sent into the vagina  90 , and then the first inner pipe  23 B is pulled away from the claw mechanism  25 B, so as to retrieve the second handle  231 B away from the positioning slot  222 B and the round hole  223 B as shown in  FIG.  11   . Thereupon, the claw mechanism  25 B can be opened to contact a periphery of the cervix  91 . 
     Referring now to  FIG.  26 B , the first inner pipe  23 B is pushed to close the claw mechanism  25 B for clamping at the periphery of the cervix  91 , by applying the second handle  231 B. 
     Referring now to  FIG.  26 C , both the second outer pipe  22 B and the first outer pipe  21 B are simultaneously pushed forward so as to have the belt  10 B to move toward the cervix  91  and to reach the periphery of the cervix  91  by surpassing the claw mechanism  25 B. Then, the first outer pipe  21 B is rotated to have the belt  10 B to tie the cervix  91  at the periphery thereof. 
     Referring now to  FIG.  26 D , apply the first handle  212 B to pull outward both the first outer pipe  21 B and the second outer pipe  22 B so as to separate both the first outer pipe  21 B and the second outer pipe  22 B away from the belt  10 B. Then, the belt  10 B can sleeve the cervix  91  at the periphery thereof. It should be noted that, at this time, the claw mechanism  25 B still clamps the cervix  91  at the periphery thereof. 
     Referring now to  FIG.  25 E , apply the second handle  231 B to pull the first inner pipe  23 B so as to open the claw mechanism  25 B, and so the cervix  91  is released from the claw mechanism  25 B. 
     Referring now to  FIG.  26 F , the entire instrument  20 B is retrieved away from the vagina  90 . Upon such an operation, the belt  10 B can tie the cervix  91  in a sleeving manner. 
     It is noted that the aforesaid operation can be arbitrarily applied to the instrument  20  of  FIG.  1    and the belt  10  of  FIG.  15 A , the instrument  20 A of  FIG.  4    and the belt  10 A of  FIG.  21 A , and the instrument  20 B of  FIG.  7    and the belt  10 B of  FIG.  24 A . No matter what style of the instrument or belt is, the operation is the same. 
     As described above, by providing a simple-structured and easy-operated device, instrument and belt to tie a cervix of a pregnant woman for avoiding preterm birth that can be applied clinically without a surgery, an anesthetic process and even hospitalization in accordance with this disclosure, the acceptability by pregnant women would be increased, and the occurrence rate of the preterm birth would be significantly reduced. 
     With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the disclosure, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present disclosure.