WO2013038223A1

WO2013038223A1 - A method performed by computer means for childbirth simulation and outcomes estimation

Info

Publication number: WO2013038223A1
Application number: PCT/IB2011/002573
Authority: WO
Inventors: Olivier AMI; Jean-Luc DUQUESNE
Original assignee: Universite Paris Sud (Paris 11)
Priority date: 2011-09-15
Filing date: 2011-09-15
Publication date: 2013-03-21

Abstract

For computing simulated childbirth parameters of a birth of a baby, the method is performed by computer means and comprises obtaining at least a first set of computer data representing a part of the baby and a second set of computer data representing the pelvis of the mother, for at least one type of descent, computing possibilities of displacements of the representation of the part of the baby into sections of the representation of the pelvis of the mother, and determining whether a simulated birth is possible for the type of descent or whether the simulated birth is not possible.

Description

A METHOD PERFORMED BY COMPUTER MEANS FOR CHILDBIRTH SIMULATION AND OUTCOMES ESTIMATION

BACKGROUND OF THE INVENTION

[0001] The present invention relates to the simulation of childbirth in order 5 to be able to ease the estimation of pressures, constraints and/or outcomes.

[0002] The approaches described in this section could be pursued, but are not necessarily approaches that have been previously conceived or pursued. Therefore, unless otherwise indicated herein, the approaches described in this section are not prior art to the claims in this application and io are not admitted to be prior art by inclusion in this section. Furthermore, all embodiments are not necessarily intended to solve all or even any of the problems brought forward in this section.

[0003] Childbirth represents the end of a human gestation period with the birth of one (or more) newborn infants from a woman's uterus.

15 [0004] The process of normal human childbirth comprises the descent and birth of the infant. This descent is quite complex as the head of the infant has to go through in the hipbone of the mother (birth canal). Then a normal birth depends on complex phases:

- Engagement of the foetal head in the transverse position: the baby's 20 head is facing across the pelvis at one or other of the mother's hips;

- Descent and flexion of the foetal head;

- Internal rotation: the foetal head rotates 90 degrees to the occipitoanterior position so that the baby's face is towards the mother's rectum;

25 - Delivery by extension: the foetal head passes out of the birth canal.

Its head is tilted backwards so that its forehead leads the way through the vagina;

- Restitution: the foetal head turns through 45 degrees to restore its normal relationship with the shoulders, which are still at an angle; - External rotation: the shoulders repeat the corkscrew movements of the head, which can be seen in the final movements of the foetal head.

[0005] If the descent of the infant is not possible in the birth canal or too difficult, childbirth is often achieved through caesarean section, the removal of the neonate through a surgical incision in the abdomen, rather than through vaginal birth.

[0006] Nevertheless, it is often difficult to determine, prior to the beginning of the birth labor, if the birth canal of the mother is large enough to allow the birth. Moreover, even if the birth canal is large enough, the pressure exerted on the head of the infant can induce internal bleedings into the infant skull.

[0007] Thus, there is a need to determine, as soon as possible, the possible pressures exerted on the infant head and the possible outcomes of the childbirth in order to ease the decision of the doctors or the midwives whether a normal childbirth is possible and is adequate for the infant and the mother.

SUMMARY OF THE INVENTION

[0008] The invention relates to a method performed by computer means for computing simulated childbirth parameters of a simulated birth of a baby through a pelvis of a mother. The method comprises:

- obtaining at least a first set of computer data representing a part of the baby and a second set of computer data representing the pelvis of the mother,

- for at least one type of descent in a set of types of descent, computing possibilities of displacements of the representation of the part of the baby into sections of the representation of the pelvis of the mother, and

- determining whether a simulated birth is possible for the at least one type of descent or whether the simulated birth is not possible for said at least one type of descent. [0009] The representation of the pelvis of the mother is of a same scale than a scale of the part of the baby.

[0010] The represented part of the baby may advantageously be the head of the baby. Nevertheless other parts may be relevant. Indeed, if a mother had already had a child and if a shoulder dystocia had occurred during the previous birth, it may be relevant to perform the presented simulation with a representation of the shoulders of the child. This part may be also the chest of child. Moreover, a combination of parts of the baby may be represented.

[0011] The wordings "baby", "foetus", "newborn", "neonate", "child" or "infant" are indistinctly used for the same close concepts. Thus, reference to "an infant", "a foetus", "a newborn", "a neonate", or "a child" is also to be construed in be a reference to "a baby" and vice versa.

[0012] The sections of the representation of the pelvis of the mother correspond to the "external" domain in the opening of the representation of the pelvis of the mother (e.g. not inside the pelvis bones themselves). The birth canal as defined below is part of these sections.

[0013] Hence, as the simulation is performed on a possible type of descent into a selection of types of descent, the simulation is not unrealistic. The selection of types of descent may correspond to a birth which is theoretically possible.

[0014] Moreover, prior to any birth labor, one may easily be informed, on the basis of such simulation data and on the basis of his own knowledge, whether a non traumatic birth (without caesarean section, instrumental delivery, nor mechanical fetal head compression) is possible.

[0015] In one possible embodiment, computing possibilities of displacements may be performed for a plurality of types of descent. Moreover, the method may also comprise computing a confidence factor. The confidence factor may be a function of: - a number of types of descent for which the simulated birth is determined as possible, and

- a number of the plurality of types of descent.

[0016] Indeed, prior to the labor, it may be difficult to predict exactly which type of descent the infant will use. Advantageously, the simulation having been performed on a plurality of types of descent, it is possible to compute a statistical factor which may take into account this difficulty.

[0017] According to another embodiment the representation of the part of the baby may be deformable. The method may also comprise determining, for a specific type of descent for which the simulated birth is determined as not possible, a reduction ratio for reducing the representation of the part of the baby for which a simulated birth with reduced representation of the part of the baby and the obtained representation of the pelvis of the mother is determined as possible for the specific type of descent.

[0018] Advantageously, one may consult the computed reduction ratio and may analyze the risk for the baby to use this type of descent. For instance, if the reduction ratio of the part of the baby is 50%, it may be considered as dangerous for the baby to use this type of descent.

[0019] In one possible embodiment, the representation of the part of the baby may be deformable. The method may also comprise determining, for a specific type of descent for which the simulated birth is determined as not possible, deformation parameters for deforming the representation of the part of the baby for which a simulated birth with the deformed representation of the baby's part and the obtained representation of the pelvis of the mother is determined as possible for the specific type of descent.

[0020] Advantageously, one may consult the computed deformation parameters and may analyze the risk for the baby to use this type of descent. For instance, if the deformation of the representation of the baby's head is consequent on a specific point of the brain, it may be considered as dangerous for the baby to use this type of descent.

[0021 ] According to another embodiment, computing possibilities of displacements comprises determining trajectory points set of at least one point of the representation of the part of the baby. The method may further comprise determining at least one force exerted on the at least one point of the representation of the part of the baby for at least one point of the trajectory points set.

[0022] Hence, the information of forces exerted on the baby's head or into the baby's head (i.e. on or into his brain) may be useful for doctors and midwifes which have to decide whether a caesarean section is a better choice and whether the exerted force is not too risky for a vaginal delivery.

[0023] In one possible embodiment, the method may further comprise determining simulated pressure in a first part of the representation of the part of the baby caused by the determined exerted force and based on mechanical characteristics of a second part of the representation of the part of the baby.

[0024] In a specific embodiment, the first and second part may be the same part.

[0025] The previous computed force may induce pressure increase in the representation of the brain. The pressure field may be influenced by mechanical characteristics such as the density, the elasticity of the representation of the brain.

[0026] In one embodiment, the brain may be modeled with a plurality of cubic meshes (for instance each mesh is a 1mmx1mmx1 mm cube: i.e. a cube of 1mm³). The first and second parts may be a cube in the plurality of meshes of the representation of the brain of the baby. Moreover, the brain may be assumed to be homogenous.

[0027] If a force is exerted on the baby's skull, the skull bones are distorted and the brain is pressurized due to this distortion. Thus, the meshes close to the skull are compressed and are conveying forces/pressure to the adjacent meshes. Step by step, the pressure increases in the representation of the brain. The conveying of the pressure field may depend on the mechanical characteristics of the brain (density, elasticity, rigidity, compressibility, etc.)

[0028] According to another embodiment, the method may also comprise comparing the determined pressure with a threshold.

[0029] Advantageously, if the exerted pressure into a part of the brain of the baby is higher than a predetermined threshold (for instance the systolic pressure) it may be impossible for the brain to be irrigated with blood. For instance, depending on the localization of the concerned anatomical part of the brain, the considered type of descent may be considered as risky by doctors having this information.

[0030] In one possible embodiment, the method may also comprise determining possible bleeding zones in a third part of the representation of the part of the baby, based:

- on the determined exerted force ; and

- on mechanical characteristics of the third part of the representation of the part of the baby and/or mechanical characteristics of the representation of the part of the baby.

[0031] Hence, depending on the localization of the possible bleeding zones the type of descent may be considered as risky by doctors having this information. [0032] According to another embodiment, the method may further comprise:

- obtaining at least a third set of computer data representing a muscle or a tissue of the mother comprising mechanical characteristics, the representation of the muscle or the tissue of the mother comprising a plurality of points,

- computing at least one force exerted on at least one point of said plurality of points, and

- determining spontaneous tearing value of the representation of the muscle or tissue based on said mechanical characteristics and on the at least one force.

[0033] Advantageously, this simulation allows determining possible traumas on the mother tissues.

[0034] Yet another aspect of the invention relates to a computation device for computing simulated childbirth parameters of a simulated birth of a baby through a pelvis of a mother. The device comprises:

- a first interface to obtain at least a first set of computer data representing a part of the baby and a second set of computer data representing the pelvis of the mother,

- a second interface to obtain at least one type of descent in a set of types of descent,

- a simulation mean to compute possibilities of displacements of the representation of the part of the baby into sections of the representation of the pelvis of the mother for the type of descent,

- a computation mean to determine whether a simulated birth is possible for said at least one type of descent or whether the simulated birth is not possible for the type of descent, and

- an output interface to deliver results of at least one computation or determination.

[0035] Moreover, the first interface may be compatible with at least one medical imagery device. Thus data delivered by commercial imagery device such as IRM or echography devices may be fully interpreted by the computation device.

[0036] Yet another aspect of the invention relates to a computer program product. This computer program product comprises a computer readable medium, having stored thereon a computer program comprising program instructions. The computer program being loadable into a data-processing unit and adapted to cause the data-processing unit to carry out the method described above when the computer program is run by the data-processing device.

[0037] Other features and advantages of the method and apparatus disclosed herein will become apparent from the following description of non- limiting embodiments, with reference to the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements and in which:

- Figure 1 is a possible sequence diagram for computations of simulated birth parameters;

- Figure 2a and 2b are examples of modeled birth canal constrained by tissues, muscles and bones;

- Figure 3a and 3b are schematic representations of infant's head and pressures/forces exerted on this head;

- Figure 4a and 4b are examples of position of mother's tissues/muscles regarding her general posture;

- Figure 5 is an example of processing device in one embodiment of the invention for computing simulated birth parameters.

DESCRIPTION OF PREFERRED EMBODIMENTS [0039] In order to simulate a childbirth, many real-time 3D simulation software (such as Vortex developed by CMS Labs, Simulia developed by Dassault Systemes, Femap with the Nastran's solver developed by Siemens) for standard 3D simulations may be available.

[0040] 3D simulators enable confrontation between modeled parts (bones, tissues, muscles, etc.) of the baby and the mother. For instance, a foetal volume representing the baby's head (referred as MESH_fofor a first modeled object and MESH_fj for the I^th iteration of the modeled object) and a maternal pelvis (referred as MESH_bo for a first modeled object and MESH_bj for the I^th iteration of the modeled object) may be modeled. [0041] In the following description, "childbirth" or "birth" may refer (except if it is mentioned otherwise) to the process of normal human childbirth which consists for the infant to go successfully through the mother's pelvis from the uterus, to the external domain.

[0042] Figure 1 is a possible sequence diagram for computations of simulated birth parameters.

[0043] MESH_fo 1 1 and MESH_b0 10 (or MESH_fi 101 and MESH_bi 100) may be typically mesh objects described, for instance in computer bytes, formatted data, according to the specification of the simulation software. [0044] MESHfo 1 1 and MESHbo 10 may also be shaped from the bone surface of the maternal pelvis and the surface of the foetus. For instance, the mesh object may be shaped by means of:

- scanners, or

- 3D echography transducer, or

- slice imaging means, or

- any other 3D medical imaging means, with manual, semi-automated, or automated reconstruction of the contours of the pelvis and foetus.

[0045] The reconstructions may also be provided by a standard model of the pelvis and foetus that can be adapted to the dimensions obtained from medical imaging (e.g. dimensions of the biparietal diameter and the head circumference taken from a foetal ultrasound, and dimensions from a traditional pelvimetry, namely the diagonal conjugate diameter, the median transverse diameter, and the bispinous diameter).

[0046] In one possible embodiment, MESHf₀ 11 can be limited to the foetal head (with a cross section plan passing just above the shoulders) to ease the simulation.

[0047] Figure 6 is a possible mesh representation of the set of data in computer format which represents a pelvis of a mother. The representation comprises for instance the Ilium (600), the sacrum (603), the symphysis pubis (601 ). Moreover, one may see a passageway (602) in which the baby head is supposed to go in.

[0048] Figure 7 is a possible mesh representation of the set of data in computer format which represents skull bones (700) of a baby.

[0049] The pelvis used for simulations may be defined as a static object (MESH_bi 100 is immovable within the 3D universe) and the foetal head used for simulations may be defined as a dynamic object (MESH_fi 101 ).

[0050] MESH_bi 100 and MESH_fi 101 may be characterized as non- deformable objects or as deformable objects especially if one wishes to determine the moulding of the head during the descent/labor. If the objects are characterized as deformable objects, the deformation may be a simple reduction of the size of each object by a given ratio or a complex deformation of specific parts of the objects corresponding to forces, pressures, etc. exerted on these parts.

[0051] Once the object modeled and characterized, a simulation is performed (step 102) to check whether, for a given type of descent, the modeled foetal head 101 is able to descent into the modeled pelvis 100. A force may be applied to the object MESH_fi 101 to move the head into the pelvis 100 when the head is above the pelvis. This force may be for instance a gravity force or alike.

[0052] The simulation (step 102) may determine (test 103) whether the baby's head (MESH_fi 101) does descend correctly in the pelvis (MESH j 100) regarding the given simulated type of descent.

[0053] In one embodiment, if the descent is impossible, a reduction of the objects by a current reduction ratio (and in particular of the baby-head MESH_fi 101) may be computed (step 105). Then, the simulation is performed again:

- until the simulation determines that the head does not descend correctly in the pelvis, or

- until a pre-determined reduction ratio threshold.

[0054] All reductions are not possible. For instance, obstetricians know that beyond a given reduction ratio of the baby's head, the risks is too high for the infant. Then, it is possible to exclude ratios beyond this given ratio from the simulation. The given ratio may be specific for each infant.

[0055] In one other possible embodiment, if the descent is impossible, a deformation of the objects (and in particular of the baby-head MESH_fj 101) may be computed (deformation parameters) (step 105) regarding the friction characteristics of the objects surface, the forces exerted and the molding properties of the objects. Then, the simulation is performed again with new deformation parameters:

- until all allowed and possible deformations have been tested without success.

[0056] All deformations are not possible. For instance, obstetricians known that the baby's head can not be deformed on specific points and along given directions because the baby's head object is then rigid. Then, it is possible to exclude these deformations from the simulation. The excluded deformations may be specific for each infant. [0057] In case of a contact (referred as a "collision" in 3D simulation software) between MESH_fi 101 and MESH_bi 100 with one or two points of each mesh, the path is deflected along the normal of the contact point, or the object are turned around the axis formed by the two contact points. In case of contact with three points, the progression of MESH_fi stops and the objects have to be reduced or deformed to continue the simulation.

[0058] The current reduction ratio or the deformation parameters may be a function of the position of the head (MESH_fi 101) in the pelvis (MESH_bj 100). For instance, the current reduction ratio may be 4% for specific points in the descent path (in case of "bottleneck") and 0% (i.e. no reduction is computed) for the other points of the path.

[0059] If the descent is possible without any reduction or deformation, the type of descent is marked (step 104a) as "possible".

[0060] If the descent is possible with a reduction (respectively with a deformation), the type of descent is marked (step 104a) as "with reduction" (respectively "with deformation") and information regarding the reduction (respectively the deformation) of the objects may be stored (step 104b) for later use (for instance the current reduction ratio, the deformation parameters, etc.).

[0061] If the descent is impossible regarding the pre-determined limit reduction ratio or the allowed deformation, the type of descent is marked (step 104a) as "impossible".

[0062] Many type of descent may be simulated. For instance, the following table presents 72 different types of descent. Descent /

Descent /

Type of Engagement rotation Expulsion rotation

descent (pelvic inlet) (pelvic pelvic outlet)

(pelvic canal)

canal)

Left Occiput

1 flexed asynclitic occipitofrontal

2 flexed synclitic occipitosacral

3 flexed synclitic occipitofrontal

4 neutral asynclitic occipitosacral

5 neutral asynclitic occipitofrontal

6 neutral synclitic occipitosacral

7 neutral synclitic occipitofrontal

8 unflexed asynclitic occipitosacral

9 unflexed asynclitic occipitofrontal

10 unflexed synclitic occipitosacral

11 unflexed synclitic occipitofrontal

Anterior Left Occiput

flexed asynclitic occipitosacral Anterior

Left Occiput

flexed asynclitic occipitosacral Posterior

Left Occiput

flexed asynclitic occipitofrontal Posterior

Left Occiput

flexed synclitic occipitosacral Posterior

Left Occiput

flexed synclitic occipitofrontal Posterior

Left Occiput

neutral asynclitic occipitosacral Posterior

Left Occiput

neutral asynclitic occipitofrontal Posterior

Left Occiput

neutral synclitic occipitosacral Posterior

Left Occiput

neutral synclitic occipitofrontal Posterior

Left Occiput

unflexed asynclitic occipitosacral Posterior

Left Occiput

unflexed asynclitic occipitofrontal Posterior

Left Occiput

unflexed synclitic occipitosacral Posterior

Left Occiput

unflexed synclitic occipitofrontal Posterior Left Occiput

flexed asynclitic occipitosacral Transverse

Left Occiput

flexed asynclitic occipitofrontal Transverse

Left Occiput

flexed synclitic occipitosacral Transverse

Left Occiput

flexed synclitic occipitofrontal Transverse

Left Occiput

neutral asynclitic occipitosacral Transverse

Left Occiput

neutral asynclitic occipitofrontal Transverse

Left Occiput

neutral synclitic occipitosacral Transverse

Left Occiput

neutral synclitic occipitofrontal Transverse

Left Occiput

unflexed asynclitic occipitosacral Transverse

Left Occiput

unflexed asynclitic occipitofrontal Transverse

Left Occiput

unflexed synclitic occipitosacral Transverse

Left Occiput

unflexed synclitic occipitofrontal Transverse

Right Occiput

flexed asynclitic occipitosacral Anterior Right Occiput

flexed asynclitic occipitofrontal Anterior

Right Occiput

flexed synclitic occipitosacral Anterior

Right Occiput

flexed synclitic occipitofrontal Anterior

Right Occiput

neutral asynclitic occipitosacral Anterior

Right Occiput

neutral asynclitic occipitofrontal Anterior

Right Occiput

neutral synclitic occipitosacral Anterior

Right Occiput

neutral synclitic occipitofrontal Anterior

Right Occiput

unflexed asynclitic occipitosacral Anterior

Right Occiput

unflexed asynclitic occipitofrontal Anterior

Right Occiput

unflexed synclitic occipitosacral Anterior

Right Occiput

unflexed synclitic occipitofrontal Anterior

Right Occiput

flexed asynclitic occipitosacral Posterior

Right Occiput

flexed asynclitic occipitofrontal Posterior Right Occiput

flexed synclitic occipitosacral Posterior

Right Occiput

flexed synclitic occipitofrontal Posterior

Right Occiput

neutral asynclitic occipitosacral Posterior

Right Occiput

neutral asynclitic occipitofrontal Posterior

Right Occiput

neutral synclitic occipitosacral Posterior

Right Occiput

neutral synclitic occipitofrontal Posterior

Right Occiput

unflexed asynclitic occipitosacral Posterior

Right Occiput

unflexed asynclitic occipitofrontal Posterior

Right Occiput

unflexed synclitic occipitosacral Posterior

Right Occiput

unflexed synclitic occipitofrontal Posterior

Right Occiput

flexed asynclitic occipitosacral Transverse

Right Occiput

flexed asynclitic occipitofrontal Transverse

Right Occiput

flexed synclitic occipitosacral Transverse Right Occiput

64 flexed synclitic occipitofrontal

Transverse

Right Occiput

65 neutral asynclitic occipitosacral

Transverse

Right Occiput

66 neutral asynclitic occipitofrontal

Transverse

Right Occiput

67 neutral synclitic occipitosacral

Transverse

Right Occiput

68 neutral synclitic occipitofrontal

Transverse

Right Occiput

69 unflexed asynclitic occipitosacral

Transverse

Right Occiput

70 unflexed asynclitic occipitofrontal

Transverse

Right Occiput

71 unflexed synclitic occipitosacral

Transverse

Right Occiput

72 unflexed synclitic occipitofrontal

Transverse

[0063] For instance, the simulation algorithm presented above may be performed on each type of descent. For instance, preselected types of descent may be stored in a database 107a. If there is at least one type of descent in the database which have not been tested (test 106) for the passage of the foetal head, a non-tested type of descent may be selected (step 107b) in the database 107a, and steps 102, 103, 104a, and 106 are executed again (and if necessary steps 105 and/or 104b) as describe above with the first modeled objects MESH_f011 and MESH o 10. [0064] The preselected types of descent may take into account that the degrees of freedom in rotation and in flexibility are limited for an infant and that his head cannot rotate by 360° easily as his shoulders block partially this rotation. Same point can be made for the flexibility. Therefore, the previous table describing several types of descent for a can be converted in a "degree of freedom" table which describes for instance :

- the base position of the foetal head object, and

- the boundaries positions of the foetal head object (with a rotation about each axis).

[0065] When all types of descent have been tested, a confidence factor F_c may be computed (step 108) as follow :

" P

F_c = Yl00— with n an integer related to the number of types of descent tested by the algorithm, and P_i a binary number representing whether the type of descent with the index i has been marked as "possible" in step 103 (i.e. P_t ; = 1 if the type of descent with the index i has been marked as

"possible", and /^> = 0 if not).

[0066] In another embodiment, p_L may be a real value in the domain [0,1] with P_t , = 1 if the type of descent with the index i has been marked as

"possible", f). = 0 if the type of descent with the index i has been marked as

"impossible", and P in ]0,1 [ if the type of descent with the index has been marked as "with deformation" or "with reduction", the value of P_t being a function of the deformation or the reduction. For instance, a reduction by a ratio 95% may be associated with a P₍ ~ 0.4 whereas a reduction by a ratio

99% may be associated with a P_t = 0.S . A correlation table may be implemented to associate the values of P_t with a given deformation or reduction. « p

[0067] The confidence factor may be also computed as F_c = Y 100 /?(/)— with p(i) a real value in the domain [0,1 ] representing a statistical probability of the incidence of the type of descent. For instance, one knows that the engagement "Left Occiput Anterior" in the pelvic inlet occurs quite often regarding the other engagement. Values of p(i) may be evaluated experimentally for each type of descent. A correlation table may be implemented to associate the values of /?(/) with the type of descent i.

[0068] Additionally, a synthesis may be provided (step 109) at the end of the simulation loop. For each type of descent tested, information stored in step 104b may be provided (such as the reduction ratio of the baby's head, deformations of the baby's head, etc).

[0069] Part of this sequence diagram may represent steps of an example of a computer program which may be executed by a computer or a specific processor/chip.

[0070] If the MESHfi 101 and MESH_bi 100 may be shaped from the bone surface of the maternal pelvis and the surface of the foetus, other objects may be modeled for the simulation process described in the Figure 1 . For instance, the following objects may be also modeled for the mother:

- bladder / urethra,

- uterus / vagina,

- rectum / anal canal,

- anal sphincter,

- anococcygeal body,

- central fibrous core of the perineum,

- coccygeal muscles,

- piriformis muscles,

- iliopsoas muscles,

- obturator internus muscles, - levator ani muscles,

- sacrospinous ligaments,

- sacrotuberous ligaments,

- sacral plexus.

[0071] Moreover, the following objects may be also modeled for the baby:

- shoulders,

- chest,

- neck.

[0072] The simulation process described in the Figure 1 is then adapted with different other modeled objects. These objects are complementary to MESHfo and MESH_bo or alternative.

[0073] In a particular embodiment, mechanical characteristics (elasticity, breaking point, deformability, etc.) may be attributed to each modeled objects. For instance, these characteristics is attributed according to the measurements of the patient's actual mechanical properties:

- tissue consistency (e.g. elastography, ultrasound or MRI), or

- composition (assessed using NMR spectrometry, for example), or

- morphology (such as the length of the levators, their surface or volume).

[0074] Therefore, it is possible to further determine during the simulation (step 103) the pressures applied to the modeled objects and to determine the deformation of these objects for a given postural attitude of the mother. Indeed, the postural attitude of the mother may influence the morphology or the tissue consistency of the modeled objects.

[0075] For instance, if the mother legs are bent, the psoas muscles is to be relaxed and if the mother legs are not bent, the psoas muscles is to be extended. In such cases, the psoas muscles are not positioned at the same coordinates and do not have the same characteristics (such as their rigidity).

[0076] Figure 4a and Figure 4b show the position of the psoas muscles 401 with flexion of the hip 403 (Figure 4a) or with extension of the hip 403 (Figure 4b) with the femur 402.

[0077] Moreover, contractions of the pelvic muscles may also influence the presentation of the foetal head.

[0078] The breaking point of soft tissues can, therefore, be assessed in step 103 by combining the analysis of stretching needed to allow for the passage of the foetal body and/or head with mechanical characteristics measured. Consequently, the risk of spontaneous tearing at the time of the labor may be computed.

[0079] The computed risk, deformations of the tissues, pressures on the baby's head, characteristics of the birth canal, etc. may then be stored (step 104b) for later use.

[0080] Once the simulation is performed for one postural attitude, the simulation may be re-executed for another postural attitude. For instance, mother's legs may be positioned in a plurality of positions by modifying angles formed by legs and the mother's spinal column by step of 1 ° or 2°.

[0081] This simulation may ease the analysis of the impact of the postural movements that the mother should realized during the labor in order to help the birth.

[0082] Typically, the modeled objects for the mother may participate to the modeling of a birth canal. A birth canal is a virtual tubular passageway through which the foetus is expelled during parturition, leading from the uterus through the cervix, vagina, and vulva. It is a dynamic passageway that may be restricted by bones (where there is very little mobility within the pelvis), and some soft tissues (that may form pairs and may be symmetrical).

[0083] The birth canal can not be seen directly by medical imaging. Nevertheless, it can be modeled using finite element analysis by following the contours of the uterus as far as its entry into the pelvic inlet, and by defining its border by passing through all of the sections of the mother's pelvis where the passage of the foetal head is possible.

[0084] For instance, Figure 2a and 2b show examples of modeled birth canal. On these Figures, the birth canal 200 is laterally restricted by the left and right iliacus muscles (211 and 212) and the left and right psoas muscles (221 and 222) at the upper part of the birth canal. Moreover the innominate bones (231 and 232) restrict the birth canal at a lower part of the birth canal on Figure 2b.

[0085] The restricted parts (aka. stricture) of the birth canal are the areas for the highest risk of dystocia due to the internal constituents' structure.

[0086] The first stricture, located higher up, corresponds with the pelvic inlet, following the lines from the sacral promontory to the upper part of the pubis. The psoas muscle borders this stricture laterally, giving an understanding of what the different postural positions influence foetal presentation during engagement and descent (for instance with a lever effect).

[0087] The first stricture may be qualified using the "Magnin index" which is the sum of the diagonal conjugate diameter and the median transverse diameter. This index is often considered as favorable if its value is higher than 23 cm, and considered as unfavorable below 20 cm.

[0088] The second stricture may be quantified using two major clinical indices:

- the " Fernstrom's mixed index" which is the sum of the bispinous diameter, the transverse diameter and the subsacral-subpubic diameter. This index is often considered as favorable if its value is higher than 3 .5 cm and as unfavorable below 29.5 cm;

- "Nicholson's pelvic outlet index" which is the product of the coccy- pubic diameter and the transverse diameter of the pelvic outlet. This index is often considered as favorable if its value is higher than 110 cm² and as unfavorable below 90 cm². [0089] If the birth canal is modeled in the simulation process described in Figure 1 , the above presented indexes and the shoulders section surface of the foetus compared with the surface of the birth canal's section along the trajectory axis may be stored and presented to an operator/doctor in order to appreciate the risk of shoulder dystocia.

[0090] The simulation 102 described in Figure 1 may provide additional information.

[0091] For instance, the simulation may compute pressure field in the foetal head object. During the birth process, the forces exerted on the modeled objects may be determined. The Figure 3a shows theses exerted forces (301 , 305, 306 and 307) on a basic representation of a foetal head 300.

[0092] If the foetal head object is deformable, it is possible to compute, regarding the mechanical properties of the head object, the inner forces (304, 303, 302) exerted onto and into the baby's brain.

[0093] This computation is useful as it is thus possible to compare the inner pressure (derived from the computed inner forces) inside the baby's brain with the systolic (or diastolic) arterial pressure inside the baby's brain arteries, as well as with the venous pressure inside the baby's venous vessels, thus defining the cerebral perfusion's pressure. The systolic (or diastolic) arterial pressure, as well as the venous pressure, may be determined, in one possible embodiment, with a statistical model of infant's brain or, in another embodiment, with direct or indirect estimation of the actual systolic (or diastolic) arterial pressure in the baby's head.

[0094] If, in a specific part of the baby's head, the brain's perfusion pressure is lower than the brain's tissular pressure due to the exerted forces during the labor process, the baby's blood may be unable to efficiently irrigate the specific part of the brain and the brain may be damaged. [0095] Moreover, the simulation may determine possible bleeding zones in an inner part of the baby's head. These bleeding zones may be caused by shear stress.

[0096] For instance, the Figure 3b shows shear stress due to the exerted forces (311 to 318) on the baby's head (300).

[0097] The upper part of the baby's head is pushed on the left side by forces (311 to 314) while the lower part of the baby's head is pushed on the right side by forces (315 to 318).

[0098] This shear stress causes a line of forces (319) which may cause bleeding inside the baby's brain. This line of force is not always circular. For instance, this line of force may depend on mechanical characteristics of the baby's brain or mechanical characteristics of the baby's skull (mobility of baby's skull bones, etc.).

[0099] Figure 5 is a representation of a possible computation device in one embodiment of the invention.

[00100] This computation device comprise an interface 501 to obtain at least a first set of computer data representing a part of the baby and a second set of computer data representing the pelvis of the mother. This interface may be connected directly to an external imagery device 511 such as IRM or echography device in order to get directly the representations of the baby or the mother. The imagery device may also be an inner part of the computation device as described herein, especially if the imagery device is sharply linked with computation device.

[00101] These sets of computer data are parameters MESHfo and MESH_bo for the simulation process described above and for instance in Figure 1. The processing device CPU 504 is arranged to execute steps of the simulation process. For instance, the CPU 504 may execute a program stored in a memory 503. The memory may also be used to stored results of the simulation or temporary data needed for the computation.

[00102] As iterations of the simulation process are performed on specific types of descent, a database 512 may be connected (for instance via a telecommunication link such as an Ethernet link) to a second interface 502. For each iteration, the CPU 504 retrieves from the database a new untested type of descent in order to perform new simulation phase. The database may also be an inner part of the computation device. In such case the database may be stored in a memory of the computation device and information in the database may be retrieved via file system accesses. This database may be, for instance, a MySQL database, a plain text file, a XML database, etc.

[00103] When every type of descent has been tested as described in processes above, the results of the simulation (or partial information) are outputted in a last interface 505. This interface may be for instance a display device 515 (such as a screen), a printer, a computer memory (such as USB, external disks), etc. Thus, doctors may be able to consult these results and determine whether a normal birth is risky or not.

[00104] Expressions such as "comprise", "include", "incorporate", "contain", "is" and "have" are to be construed in a non-exclusive manner when interpreting the description and its associated claims, namely construed to allow for other items or components which are not explicitly defined also to be present. Reference to the singular is also to be construed in be a reference to the plural and vice versa.

[00105] A person skilled in the art will readily appreciate that various parameters disclosed in the description may be modified and that various embodiments disclosed may be combined without departing from the scope of the invention.

Claims

1. A method performed by computer means for computing simulated childbirth parameters of a simulated birth of a baby through a pelvis of a mother, wherein the method comprises:

- obtaining at least a first set of computer data (10) representing a part of the baby and a second set of computer data (11) representing the pelvis of the mother,

- for at least one type of descent in a set of types of descent (107a), computing (102) possibilities of displacements of the representation of the part of the baby (10) into sections of the representation of the pelvis of the mother (11), and

- determining (103) whether a simulated birth is possible for said at least one type of descent or whether the simulated birth is not possible for said at least one type of descent, wherein representation of the pelvis of the mother (11 ) is of a same scale than a scale of the part of the baby (10).

2. The method of claim 1 , wherein computing possibilities of displacements is performed for a plurality of types of descent, and wherein the method further comprises computing (108) a confidence factor being a function of a number of types of descent for which the simulated birth is determined as possible and of a number of the plurality of types of descent.

3. The method of any one of the preceding claims, wherein the representation of the part of the baby (10, 100) is deformable, and wherein the method further comprises determining, for a specific type of descent for which the simulated birth is determined as not possible (103), a reduction ratio (105) for reducing the representation of the part of the baby (100) for which a simulated birth with reduced representation of the part of the baby and the obtained representation of the pelvis of the mother (101 ) is determined as possible for the specific type of descent.

4. The method of any one of the preceding claims, wherein the representation of the part of the baby is deformable (10, 100), and wherein the method further comprises determining (103), for a specific type of descent for which the simulated birth is determined as not possible, deformation parameters (105) for deforming the representation of the part of the baby (100) for which a simulated birth with the deformed representation of the baby's part (100) and the obtained representation of the pelvis of the mother (101 ) is determined as possible for the specific type of descent.

5. The method of any one of the preceding claims, wherein computing ( 02) possibilities of displacements comprises determining trajectory points set of at least one point of the representation of the part of the baby, wherein the method further comprises determining at least one force (301 ,

305, 306, 307, 311 to 318) exerted on the at least one point of the representation of the part of the baby (100) for at least one point of the trajectory points set.

6. The method of claim 5, wherein the method further comprises determining simulated pressure in a first part of the representation of the part of the baby (100) caused by the determined exerted force (301 , 305,

306, 307, 311 to 318) and based on mechanical characteristics of a second part of the representation of the part of the baby (100).

7. The method of claim 6, wherein the method further comprises comparing the determined pressure with a threshold.

8. The method of any one of claims 5 and 6, wherein the method further comprises determining possible bleeding zones (319) in a third part of the representation of the part of the baby (100) based:

- on the determined exerted force ; and

- on mechanical characteristics of the third part of the representation of the part of the baby (100) and/or mechanical characteristics of the representation of the part of the baby (100).

9. The method of any one of the preceding claims, wherein the method further comprises:

- obtaining at least a third set of computer data representing a muscle or a tissue of the mother (212, 222, 221 , 211 , 232, 232) comprising mechanical characteristics, the representation of the muscle or the tissue of the mother (212, 222, 221 , 211 , 232, 232) comprising a plurality of points,

- determining spontaneous tearing value of the representation of the muscle or tissue (212, 222, 221 , 211 , 232, 232) based on said mechanical characteristics and on the at least one force.

10. A computation device for computing simulated childbirth parameters of a simulated birth of a baby through a pelvis of a mother, wherein the device comprises: - a first interface (501 ) to obtain at least a first set of computer data (10) representing a part of the baby and a second set of computer data (11) representing the pelvis of the mother,

- a second interface (502) to obtain at least one type of descent in a set of types of descent,

- a simulation mean (504) to compute possibilities of displacements of the representation of the part of the baby (10) into sections of the representation of the pelvis of the mother (11 ), and

- a computation mean (504) to determine (103) whether a simulated birth is possible for said at least one type of descent or whether the simulated birth is not possible for said at least one type of descent,

- an output interface (505) to deliver results of at least one computation or determination.

11. The computation device of claim 10 wherein the first interface is compatible with at least one medical imagery device.

12. A computer program product comprising a computer readable medium, having stored thereon a computer program comprising program instructions, the computer program being loadable into a data-processing unit and adapted to cause the data-processing unit to carry out the steps of any of claims 1 to 9 when the computer program is run by the data-processing device.