ABNORMAL

 

INTRODUCTION

 

          Do you know the meaning of word ‘abnormal’.  It is nothing but something that deviates from normal.  Pelvic abnormalities may arise from various causes.  In a contracted pelvis, which is common cause of dystocia, one or more of the diameters in one or more of the planes is shorter than normal.  The contraction may be symmetrical or asymmetrical, thus causing a varieties of deformaity.  The main contents of this assignment that we are going to discuss are the definition, types, causes, diagnosis and management of contracted pelvis.

ABNORMALITIES OF BONY PELVIS

CONTRACTED PELVIS

Definition:

          Anatomically, contracted pelvis is defined as the one where the essential diameters of one or more planes are shortened by 0.5cm.

          Obstetric definition states that alteration in the size and / or shape of the pelvis of sufficient degree so as to alter the normal mechanism of labour in an average size baby.

Classification

          Munro-Kerr’s classification based on etiology is given below.

1.  Deformities arising from the faculty development

A. Minor defects

·        Gynaecoid pelvis

·        Anthropoid pelvis

·        Android pelvis

·        Platypelloid pelvis

B. Naegele’s pelvis

C. Robert’s pelvis

D. High or low assimilation pelvis

2. Deformities due to dietary deficiencies

A.  Rachitie pelvis

b. Ostromalacic pelvis

3.  Deformities arising from diseases or injuries of the pelvic bones and joints

A. Fractures

B. Congenital dislocation of the hip

C. Polio – myelitis

4. Deformities resulting from diseases of the spinal column

A. Kyphosis

B. Scoliosis

C. Spondylolisthesis

5. Deformities arising from disease of lower extremities

A. Coxitis

B. Dislocation of one or both femurs

C. Atrophy or loss of one limb

Incidence:

          The incidence is more in developing countries because of under nutrition.

Etiology

          The common causes of contracted pelvis are

I. Faulty development of pelvis

1. NAEGELE’S PELVIS

          In the Naegele’s Pelvis one sacral ala is missing and the sacrum is fused to the ilium, causing grossly asymmetric brim.

          It may be

Congenital

                             Acquired (osteitis of the sacroiliac joint)

          In case of Naegele’s pelvis  method of delivering is by caesarean section.

2.ROBERT’S PELVIS

          In this case sacral ala of the both the sides are absent and the sacrum is fused with the innominate bones.  This is an extremely rare abnormality.  Delivery is done by caesarean section.

3. HIGH ASSIMILATION PELVIS

          This type of pelvis is seen when the 5^th lumbar vertebrae is fused to the sacrum and the angle of inclination of pelvic brim is increased.  In this case engagement of the fetal head is difficult, but once achieved, labour progresses normally.

4. MINOR DEFECTS

          There are four parent types of pelvis with defect in shape of inlet.  They are

a.    Gynaecoid

b.    Anthropoid

c.    Android

d.    Platypelloid

II. Dietary deficiencies

          Deficiency of Vitamins and minerals necessary for the formation of healthy bones.

1. RACHITIC PELVIS:

          This occurs due to Rickets in early childhood.  The changes occurs in the pelvic bones are:-

·        Inlet: Sacral promontory is pushed downwards and forewards producing a “reniform” shape of the inlet with marked shortening of the anterioposterior diameter and widening of transverse diameter.

·        Cavity: Sacrum is flat and tilted backwards.

·        Outlet: Widening of transverse diameter and the public arch

 

2. OSTEOMALACIC PELVIS:

          This occurs due to softening of the pubic bones due to calcium and vitamin D deficiency and lack of exposure to sunrays.  The changes occurs in the pelvic bones are,

·        Inlet: Sacral promntary is pushed downwards and forwards and lateral pelvic walls are pushed inwards.  So the shape of inlet is triradiate.

·        Marked narrowing of the public arch.

·        Sacrum is markedly shortened.

·        Coccyx is pushed forward.

III. Diseases or injuries of pelvic bones and joints

·        Fractures

·        Tumourrs

·        Tubercular arthritis

·        Congenital lip dislocation

IV. Diseases of the spinal column

·        Kyphosis

·        Scoliosis

·        Spondylolisthesis

 

1) Kyphotic pelvis:

          This deformity is secondary to kyphotic changes of the vertebral column either following tuberculosis or rickets.

          The changes occurs  in the pelvic bones are,

·        Sacrum is tilted backwards in the upper part and forwards in the lower part.

·        Anterioposterior diameter of inlet is increased but is diminished at the outlet.

·        Subpubic angles is narrow.

In Kyphotic pelvis malpresentation is common.  Method of delivery is by caesarean section.

 

2. Scoliotic Pelvis:

          This is due to the scoliosis involving the lumbar region.  Oblique asymmetry of the pelvis results in contraction of one of the oblique diameters.  Caesarean section is the only safe method of delivery.

V. Disease of lower extremities

Eg: Poliomelitis, Dislocation of femor etc.

DIAGNOSIS

1. Past History

a) Medical

          Past history of fracture, rickets, osteomalacia, tuberculosis of the pelvic joints or spines, and poliomyrlitis is to be enquired.

b) Ostetrical

          History of prolonged and a tedious labour followed by either spontaneous or difficult instrumental delivery

2. Physical examination

a. Short statured woman

b. Deformities of spine

3. Abdominal examination

·        Inspection : Pendulous abdomen.

·        Obstetrical examination for malpresentation and CPD.

·        Assessment of pelvis (pelvimetry)

o   Clinical pelvimetry

o   Radio pelvimetry

o   Computed Tomography (CT)

o   Magnetic resonance imaging (MRI)

4. Vaginal Examination

          It helps to assess the pelvic capacity and the following must be examined.

·        Sub-pubic arch.

·        The ischial spines

·        The sacral concavaity

·        Length of the sacrtuberous ligament

·        Pelvic side walls

·        Diagonal conjugate

 

EFFECTS OF COTNRACTED PELVIS ON PREGNANCY AND LABOUR

PREGNANCY

·        There is more chance of incarceration of the retroverted gravid uterus in flat pelvis.

·        Abdomen becomes pendulous specially in multigravidae.

·        Malpresentations are increased 3-4 times.

LABOUR

·        Early rupture of membranes

·        Cord prolapse

·        Cervical dilation is slowed.

·        Prolonged labour.

·        Obstructred labour with features of exhaustion, dehydration, ketoacidocis and sepsis.

·        Increased incidence of operative interference, shock, post partum haemorrhage and sepsis.

 

MATERNAL INJURIES

·        Increased incidence of cervical tear, vaginal and perineal lacerations.

·        There is a chance of rupture of uterus in multigravida.

·        Increased chance of sloughing vesicovaginal and occasional rectovaginal fistula.

FETAL HAZARDS

·        Trauma

·        Asphyxia

·        Prolpas of cord

·        Extreme moulding of head

MANAGEMENT

          The three important management includes

1.    Preterm induction of labour

2.    Elective caesarean section at term.

3.    Trial labour

 

PRETERM INDUCTION OF LABOUR

        Preterm induction of labour is indicated in moderate degrees of pelvic contraction.  In selected multigravidae, with previous history of difficult vaginal delivery of an average size baby, the method may be employed 2-3 weeks prior to due date.

 

ELECTIVE CAESAREAN SECTION AT TERM

Indications are

·        Major degree of inlet contraction.

·        Moderate degree of inlet contraction associated with outlet contraction.

·        Complicating factors like

o   Elderly primigravidae

o   Malpresentation

o   Post Caesarean pregnancy

TRIAL LABOUR

Definition:

          It is the conduction of spontaneous labour in a moderate degree of cephalo-pelvic disporoportion,in an institution under supervision with watchful expectancy, hoping for a vaginal delivery.

 

Aims:

·        Avoiding an unnecessary caesarean section.

·        Delivering a healthy baby

Contraindications:

·        Associated midpelvic and outlet contraction.

·        Elderly primigravida

·        Malpresentation

·        Post maturity

·        Post caesarean pregnancy

·        Pre-eclampsia

·        Medical disorders

o   Heart disease

o   Diabetes

o   Tuberculosis

Nurse’s responsibilities during Trial labour

·        The labour should ideally be spontaneous in onset.

·        Oral feeding remains suspended and hydration is maintained by intravenous drip.

·        Adequate analgesic is administered.

·        The progress of labour is observed by noting.

o   Progressive descent of fetus

o   Progressive dilatation of cervix

·        If there is failure to progress due to inadequate uterine contraction, augmentation of labour may be done by amniotomy along with oxytocin infusion.

·        Watch carefully the maternal and fetal conditions

·        After the rupture of membranes, pelvic examination is to be done

o   To exclude cord prolapse

o   To note the colour of liquor

o   To assess the pelvis

o   To note the pressure of presenting part on the cervix.

o   Rate of descent of head.

How long the trial to be continued?

          If the progress is satisfactory and the maternal and fetal condition remain good, trial may be continued safely.  But if any ominous features appear and if there is arrest of descend of head and dilatation of cervix for a reasonable period (3-4 hours) in the active phase, trial labour should be terminated, by caesarean section.

Termination of trial labour:

          He methods of termination are anyone of the following.

·        Spontaneous delivery with or without episiotomy.

·        Forceps or ventous delivery

·        Caesarean section.

Successful Trial:

          A trial is called successful, if a healthy baby is born vaginally, spontaneously or by forceps or ventous with the mother in good condition.

Failure of Trial labour:

Delivery by caesarean section or delivery of a dead baby, spontaneously or by craniotomy is called failure of traial labour.

Advantages of trial labour:

·        It eliminates unnecessary caesarean section.

·        It eliminates injudicious use of premature induction of labour.

·        A successful trial ensures the woman a good future obstetrics

Disadvantages of trial labour

·        Increased perinatal mortality or morbidity due to asphyxia or intracranial haemorrhage.

·        Increased maternal morbidity

 

 

CONCLUSION

 

          Early diagnosis and proper management of pelvic abnormalities is important for the maternal and fetal prognosis.  If no proper care is available, the results can be disastrous for both mother and child.  As a result of obstructed labour, the mother may die from rupture uterus and the fetus from asphyxia.  So a careful assessment and proper management should be done to save the life of mother and baby during the labour.

 

 

BIBLIOGRAPHY

 

1.     D.C.Dutta’s “Text Book of Obstetrics” Edition, 6^th Pg.no.345-356.

 

2.     Mudaliar and Menon’s, ‘Clinical Obstetrics’ Edition, 9^th Pg.No.330-338.

 

3.     Annamma Jacob’s, “A comprehensive textbook of Midwifery”, Edition, 2^nd Pg.No.49-50.