Pregnancy and labor at fetal malpresentations and abnormal pelvis

Prepared by N. Bahniy

The main external pelvic sizes D. Spinarun - distance

between anterior superior iliac spines from both sides. It has 25-26 cm.

D. Cristarum – distance between iliac crista from both sides. It is 28-29 cm.

D. Trochanterica – distance between trochanter majors from both sides. It has 31-32 cm.

C. Externa - distance between midpoint of superior surface of the symphysis pubis and suprasacralis fossa. It has 20-21 cm

Michaelis’ Rhomb and Solovjov index

Vertical 11cm, transverse – 10cm

Solovjov index- radiocarpal joint circumference. 14-16 cm

Additional external pelvic sizes

Lateral conjugate –is a distance between the anterior superior iliac spine and posterior superior iliac spine of the same iliac bone. It has 14.5-16 cm.

Oblique conjugate –is a distance between the right anterior superior iliac spine to the left posterior superior iliac spine. It has .20-21cm.

Additional external pelvic sizes

Anteroposterior diameter of the pelvic outlet is a distance between the lower par4t of symphysis pubis and apex of the coccyx. It has 9.5 cm.

Transverse diameter of the pelvic outlet is a distance between the posterior portions of the ishial tuberosities. It has 11.5 cm.

Solovjov’ index. It is estimated by the circumference of radiocarpal joint. It has 14-16 cm and indicates into bones’ pelvic thickness.

Obstetric conjugate (widest anteroposterior diameter of the pelvic ) – 11cmIndirect ways of true conjugate

estimation:

Diagonal conjugate, usually exceeds the obstetric conjugate by 1.5 to 2 cm.

External conjugate exceeds the obstetric conjugate by 9 cm.

Vertical dimension of Michael’s’ rhomb equal obstetric conjugate.

Estimation of diagonal conjugate

Fetal head station

-2 (fixed to pelvic inlet) -1(small segment of fetal

head in pelvic inlet) 0 (large segment of fetal

head in pelvic inlet) +1 (fetal head in plane of

greatest dimension) +2 (fetal head in plane of

least dimension) +3 (fetal head in the pelvic

outlet)

Diameters of the fetal head at term

1. The suboccipitobregmatic (9.5 cm, 32cm), which follows from the middle of the large fontanel to the undersurface of the occipital bone.

2. The suboccipitofrontalis (10cm,33 cm) – from subocipital fossa to border of the hair.

3. The occipitofrontal (12 cm, 34 cm), which follows a line extending from a point just above the root of the nose to the most prominent portion of the occipital bone.

4. The occipitomental (12.5-13 cm, 39-41cm), from the chin to the most prominent portion of the occiput.

5.The sublingquobregmatica (9,5 cm, 32 cm).

6. The biparietal (9.5 cm), the greatest transverse diameter of the head, which extends from one parietal boss to the other.

7. The bitemporal (8.0 cm), the greatest distance between the two temporal sutures.

Transverse lie

Oblique lie

Breech presentations

Circumference of the buttocks – 32cmC.of the shoulders – 39-41cmC. of fetal head – 32cm

Circumference of the buttocks – 34-35cmC.of the shoulders – 34-35cmC. of fetal head – 32cm

Circumference of the buttocks – 28cmC.of the shoulders – 34-35cmC. of fetal head – 32cm

From 30-32 weeks -correcting gymnastics

External cephalic version – at 32-36 weeks of gestation

Management

Breech presentations

– cesarean section !

The manual aid by Tsovyanov I in frank breech presentation

Aim: to keep normal fetal attitude.The extremities are flexed at the hips and extended at the knees and thus the feet lie in close proximity to the head.

The circumference of the thorax with the crossing on it arms and legs is larger than circumference of the head and the after-coming head deliveries easily.

The manual aid by Tsovyanov II in footling presentations

The aim: to transform the footling presentation to the incomplete breech and to prepare the maternal ways to the delivery of the head and shoulders.

The doctor puts up resistance

to the delivery of the feet. The feet are flexing and the footling presentation becomes complete breech presentation.

The classic manual aid begins when the lower angular of the anterior scapula became visible Aim: delivery of the

shoulders and the head when in 2 pushing efforts they are not delivered.

There are 4 moments of the classic manual aid:

I - delivery of the posterior arm.

II – transformation anterior arm into posterior one

III – delivery of the second arm

IV – delivery of the head by Mauriceau-Levre maneuver

Dexlefed presentations

Sinciput vertexD. fronto-occipitalis12cm, 34cm

BrowD.Mentooccipitalis13 – 13,5cm, 39-41cm

FaceD. hyo-bregmaticus9.5cm, 32cm

Sinciput vertex presentation In vaginal exam: sagittal suture,

large and small fontanels are on the same level.

The fetal head presents with a fronto-occipital diameter – 12cm

The leading point is the large fontanel.

The cardinal movements in labor: deflexion; internal rotation; flexion; extension; internal rotation of body and

external rotation of fetal head.

Vaginal Delivery is possible in posterior variety in:

Not large fetus Adequate uterine

contractions Normal pelvic sizes

Brow presentationIn vaginal exam: the frontal

suture, the large fontanel, orbital ridges, eyes, and root of the nose. The nose and mouth can not be palpable.

The fetal head presents with a mento-occipital diameter – 13 – 13,5cm

The leading point is the middle of the frontal suture.

Vaginal delivery is impossible, only cesarean section is recommended.

Face presentationOn vaginal exam: face line

with mouth, nose, the, orbits and chin are presented

The leading point is chinThe fetal head presents with

hyo-bregmaticus diameter 9,5cm

The cardinal movements in labor are:

deflexion; internal rotation; extension; internal rotation of the fetal

body and external rotation of the fetal head.

Vaginal delivery – in face posterior(chin anteriorly)

Cesarean section in face posterior.

CONTRACTED PELVIS

Anatomically contracted pelvis is characterized by shortening of all or one diameters of the true pelvis into 1,5 - 2 cm and more.

Clinically or functional contracted pelvis - pelvis with normal dimensions, but vaginally delivery is impossible due to “cephalopelvic disproportion”.

The main causes: fetal macrosomia postdate pregnancy uterine inertia fetal malpresentation, especially fetal head

extension – sinciput vertex, brow, face anterior position.

Signs of clinically contracted pelvis1.Arresting of the head in the pelvic inlet 2.Uterine contractions abnormality.3. Positive Vasten’ sign 4. Signs of urinary bladder compression.5. Edema of the cervix, and vaginal walls, productions of fistulas.6. Danger of uterine rupture – overdistension of lower uterine

segment7. Pushing occurs in location of fetal head in inlet.

PositiveNegative

At the same level

Uterine rupture

In clinically contracted pelvis – only cesarean section

Pelvic classification according to form of contractions

1. Often occurred generally contracted pelvis; flat pelvis: simple flat pelvis, flat rachitic pelvis, generally contracted flat

pelvis.2. Rare occurred: obliquely contracted pelvis, obliqualy dislocated pelvis, transverse contracted pelvis, osteomalacic pelvis, funnel-shaped pelvis, spondylolisthetic pelvis, contracted pelvis as a result of exostosis and bone tumors. Management of labor. Cesarean section should be performed in all of these

types of pelvis.

Pelvic classification according to degree of contraction

Four degrees of pelvic contractions should be distinguished:

I degree – True conjugate is 11-9 cm. Vaginal delivery is possible.

II degree – True conjugate is 9-7,5 cm. Vaginal delivery is possible.

III degree – True conjugate is 7,5 – 5,5 cm Cesarean section is performed.

IV – degree – True conjugate is 5.5 cm. Cesarean section is performed.

Generally contracted pelvis

Is characterized by diminution of all true pelvic diameters (anteroposterior, transverse, and oblique) into 1-2 cm. Subpubic arch is narrow.

Average sizes of the pelvis are: D. spinarum – 23 cm, D. cristarum – 26 cm. D. trochanterica - 29 cm C. externa – 18 cm C. diagonalis – 11 cm C. vera – 9 cm.

Course of labor in generally contracted pelvis

prolongation of labor considerable fetal head flexion thanks to which it is

elongated in the ocipitofrontal diameter (dolichocephaly) posterior fontanel is situated into the axis of pelvis considerable molding of the fetal head. Caput

succedaneum is formed in the area of posterior fontanel with increasing narrowing of the pubic arch, the occiput

cannot emerge directly beneath the symphysis as a result perineal tears occur.

Management of labor. Vaginally delivery is possible.

Simple flat pelvis

Is defined as shortening of anteroposterior diameters at all levels of true pelvis, as a result of this sacrum is inclined anteriorly to pubis.

Average sizes of the pelvis are: D. spinarum – 26cm D. cristarum – 29 cm D. trochanterica - 31 cm C. externa – 18 cm C. diagonalis – 11 cm C. vera – 9 cm.

Flat rachitic pelvis True conjugate is shortened.

Sidewalls tend to converge, as result of this D. spinarum and D. cristarum are the same.

Additional promontorium may be presented between 1 and 2 vertebrae of sacrum

Subpubic arch is shallow and wide Top of the sacrum is situated posteriorly that’s why

dimensions of the pelvic outlet are normal or even increased. Average sizes of the pelvis are: D. spinarum – 26cm D. cristarum – 26 cm D. trochanterica - 31 cm C. externa – 17 cm C. diagonalis – 10 cm C. vera – 8 cm. .

Course of labor in flat pelvis prolongation of labor; sagittal suture arresting in the transverse diameter of the

plane of inlet; anterior fontanel is the leading point of the fetal head asynclitism should be presentedManagement of labor. In the case of posterior asynclitism

cesarean section should be performed. Vaginal delivery in a flatrachitic pelvis

Generally contracted flat pelvis

Is characterized by combination of the signs of generally contracted and flat pelvis.

Average sizes of the pelvis are: D. spinarum – 24cm D. cristarum – 25 cm D. trochanterica - 28 cm C. externa – 16 cm C. diagonalis – 9 cm C. vera – 7 cm. Course of labor depends from predominance of kind of pelvis

contraction. Management of labor. Cesarean section is the method of choice.