CPD-converted - obstetrical and gynaecological nursing PDF

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obstetrical and gynaecological nursing...

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SEMINAR ON CPD

CONTRACTED PELVIS DEFINITION Anatomically, contracted pelvis is defined as one where the essential diameters of one or more planes are shortened by 0.5 cm. The obstetric definition which 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. Depending upon the degree of contraction, the head may pass through the pelvis by abnormal mechanism or fail to pass due to absolute obstruction. VARIATIONS OF FEMALE PELVIS The size and shape of the female pelvis differ so widely due to morphological factors such as developmental, sexual, racial and evolutionary that it is indeed difficult to define what the features of a normal pelvis are. However, on the basis of the shape of the inlet, the female pelvis is divided into four parent types

• Gynecoid (50%) • Anthropoid (25%) • Android (20%) • Platypelloid (5%)

But more commonly, intermediate forms with combination of features are found. They are termed as gyneandroid or andro-gynecoid etc. The first part of the nomenclature relates to

features of the posterior segment and the second part relates to that of the anterior segment of the pelvis. All types of combinations are possible except anthropoid with platypelloid. Thus, there may be 14 types of parent pelves either in pure form or in combination. It should be clear that the pelves which are not typically female, are not necessarily contracted, although there may be deviation of normal mechanism of labour. However, slight contraction if associated with any of the three nongynaecoid pelves, has a more serious consequence because of the unfavourable shape. Anatomical features of parent pelvic types

1. Inlet

2. cavity

Gynecoid Round

Anthropoid Anteroposteriorly

Android Oval

Antero posterior segment

Almost equal and spacious

Sacrum

Posterior segment short and anterior segment narrow Sacral angle less than 90°. Inclined forwards and straight

Pubic arch

Sacral angle (SA) more than 90°. Inclined backwards. Well curved from above down and side to side Wide and shallow Straight or slightly divergent Not prominent Curved

Both increased with slight anterior narrowing SA more than 90°. Inclined posteriorly. Long and narrow. Usual curve

Sub pubic angle

Wide (85°)

Shape

Sciatic notch Side walls

3. Outlet

Ischial spine

Bituberous diameter Normal

Platypelloid Triangular Transversely oval Both reducedflat

SA more than 90°. Inclined posteriorly. Short and straight

More wide and Narrow and deep Slightly narrow shallow and small Straight or Convergent Divergent divergent Not prominent

Prominent

Not prominent

Long and curved Slightly narrow

Long and straight

Short and curved

Narrow

Normal or

Short

Very wide (more than 90°) Wide

short

ETIOLOGY OF CONTRACTED PELVIS Gross degree of contracted pelvis is nowadays a rarity. Severe malnutrition, rickets, osteomalacia and bone tuberculosis affecting grossly the pelvic architecture are now rarely met in clinical practice. Instead, minor variation in size and/or shape of the pelvis is commonly found which is often over-looked until complication arises. Common causes of contracted pelvis are: (1) Nutritional and environmental defects — • Minor variation: common • Major: Rachitic and osteomalacic — rare (2) Diseases or injuries affecting the bones of the pelvis — fracture, tumours, tubercular arthritis; (3) Spine deformities — • Lumbar Kyphosis • Lumbar scoliosis • Spondylolisthesis – the 5th lumbar vertebrae with the above vertebral column is pushed forward while the promontory is pushed backwards and the tip of the sacrum is pushed forwards leading to outlet contraction • Coccygeal deformity; (4) Deformities of lower limbs — Poliomyelitis, hip joint disease. (3) Development defects — • Naegele’s pelvis – absence of one sacral ala, • Robert’s pelvis – Absence of both sacral alae • High assimilation pelvis - the sacrum is composed of 6 vertebrae. • Split pelvis – split symphysis pubis RACHITIC FLAT PELVIS: Rickets is predominantly a disease of early childhood when the bones remain soft and unossified. In childhood changes occur in the bony pelvis due to weight bearing . The classic changes are seen in the pelvic bones . Inlet: Sacral promontory is pushed downwards and forwards producing a “reniform” shape of the inlet with marked shortening of the antero-posterior diameter without affecting the transverse diameter, which is often increased .

Cavity: Sacrum is flat and tilted backwards. There may be sharp angulation at the sacrococcygeal joint. Outlet: Body weight transmitted through the ischium in sitting position results in widening of the transverse diameter of the outlet and the pubic arch. Rachitic pelvis: (A) Effect of walking; (B) Effect on lying down position; (C) Reniform shape of the inlet

OSTEOMALACIC PELVIS The deformity is caused by softening of the pubic bones due to deficiency of calcium and vitamin D and lack of exposure to sunrays. It usually affects women after they have reached maturity. The changes in the pelvic bones are : • The promontory is pushed downwards and forwards and the lateral pelvic walls are pushed inwards causing the anterior wall to form a beak. • The shape of the inlet thus becomes triradiate. • Approximation of the two ischial tuberosities occurs. • Sacrum is markedly shortened. • Coccyx is pushed forward. • Vaginal delivery is unlikely and cesarean section is ideal. ASYMMETRICAL OR OBLIQUELY CONTRACTED PELVIS It is seen in (1) Naegele’s pelvis (2) Scoliotic pelvis (3) Due to disease affecting one hip or sacroiliac joint (4) Tumors or fracture affecting one side of the pelvic bones during growing age. Naegele’s pelvis This type of pelvis is extremely rare. It is produced due to arrested development of one ala of the sacrum . • It may be (i) Congenital or (ii) Acquired (osteitis of sacroiliac joint). Congenital variety may be associated with urinary tract and may of the same side. The pelvis is obliquely

• • • • •

contracted at all levels but more marked in the outlet. Ilio-pectineal line on the affected side is almost straight. Method of delivery is by cesarean section. Scoliosis involving only the lumbar region will cause deformity of the pelvis . The acetabulum is pushed inwards on the weight bearing side. This may be pronounced if the disease occurs during early life. Oblique asymmetry of the pelvis results in contraction of one of the oblique diameters. Cesarean section is the only safe method of delivery.

Robert’s pelvis (transversely contracted pelvis) This is an extremely rare abnormality. Ala of both the sides are absent and the sacrum is fused with the innominate bones. Delivery is done by cesarean section.

KYPHOTIC PELVIS This pelvic deformity is secondary to the kyphotic changes of the vertebral column either following tuberculosis or rickets. The deformities observed with lumbar kyphosis are: The sacrum is tilted backwards in the upper part and forwards in the lower part. It is narrow and straight. The anteroposterior diameter of inlet is increased but is diminished at the outlet. Subpubic angle is narrow. Thus, the feature is an extreme funnelling of the pelvis. Abdomen becomes pendulous due to the shortened distance between the symphysis pubis and xiphisternum. Malpresentation is common. Mechanical distress is evident. Cesarean section is ideal and one may have to do the classical operation because of poor formation of the lower segment or for technical reasons.

Osteomalacic pelvis

Naegele’s pelvis

Scoliotic pelvis

DIAGNOSIS OF CONTRACTED PELVIS

During the past couple of decades there has been a gradual decline in the incidence of severe degree of contracted pelvis. This is due to an improved standard of living and of nutrition in

particular. But of significance is the presence of feto pelvic disproportion due either to inadequate pelvis or big baby or more commonly a combination of the both. Past History Medical: Past history of fracture, rickets, osteomalacia, tuberculosis of the pelvic joints or spines, poliomyelitis is to be enquired. Obstetrical: While an uncomplicated, previous safe vaginal delivery of an average size baby reasonably excludes pelvic contraction, a history of prolonged and a tedious labour followed by either spontaneous or difficult instrumental delivery is suggestive of pelvic contraction. Difficult vaginal delivery ending in stillborn or early neonatal death or late neurological stigmata following a difficult labour without any other etiological factor points towards contracted pelvis. Weight of the baby, evidences of maternal injuries such as complete perineal tear, vesico-vaginal or recto-vaginal fistula, if available, are of useful guide. Physical Examination Stature: A small woman of less than 5 ft is likely to have a small pelvis. She is likely to have a small baby also. However, this does not mean that tall women always have a good pelvis. Dystocia dystrophia syndrome: This syndrome is characterized by the following features: - The patient is stockily built with bull neck, broad shoulders and short thighs. - She is obese with a male distribution of hairs. - They are usually subfertile, having dysmenorrhea, oligomenorrhea or irregular periods. - There is increased incidence of pre-eclampsia and a tendency for postmaturity. - Pelvis is of the android type. - Occipito-posterior position is common. - During labor, inertia is common and there is a tendency for deep transverse arrest or outlet dystocia leading to either increased incidence of difficult instrumental delivery or cesarean section. - There is a chance of lactation failure. Abdominal Examination Inspection: Pendulous abdomen specially in primigravidae, is suspicious of inlet contraction. Obstetrical: In primigravidae, usually there is engagement of the head before the onset of labor. Presence of malpresentation in primigravidae, gives rise to a suspicion of pelvic contraction. Assessment of the pelvis (pelvimetry): Assessment of the pelvis can be done by bimanual examination: clinical pelvimetry or by imaging studies — Radio-pelvimetry, Computed Tomography (CT) and Magnetic Resonance Imaging (MRI).

Clinical pelvimetry: This is done manually. Time: In vertex presentation, the assessment is done at any time beyond 37th week but better at the beginning of labor. Because of softening of the tissues, assessment can be done effectively during this time. Procedures: The patient should empty the bladder. The pelvic examination is done with the patient in dorsal position under aseptic techniques. The following features are to be noted simultaneously: (1) State of the cervix (2) To note the station of the presenting part in relation to ischial spines (3) To test for cephalopelvic disproportion in non engaged head (described later) and (4) To note the resilience and elasticity of the perineal muscles. Steps: The internal examination should be gentle, thorough and purposeful . It should be seen that the sterilized gloved fingers once taken out should not be reintroduced. Sacrum — The sacrum is smooth, well curved and usually inaccessible beyond lower three pieces. The length, breadth and its curvature from above down and side to side are to be noted. Sacrosciatic notch — The notch is sufficiently wide so that two fingers can be easily placed over the sacrospinous ligament covering the notch. The configuration of the notch denotes the capacity of the posterior segment of the pelvis and the side walls of the lower pelvis. Ischial spines — Spines are usually smooth (everted) and difficult to palpate. They may be prominent and encroach to the cavity thereby diminishing the available space in the mid pelvis. Ilio-pectineal lines — To note for any beaking suggestive of narrow fore pelvis (android feature). Sidewalls — Normally they are not easily palpable by the sweeping fingers unless convergent. Posterior surface of the symphysis pubis — It normally forms a smooth rounded curve. Presence of angulation or beaking suggests abnormality. Sacrococcygeal joint — Its mobility and presence of hooked coccyx, if any, are noted. Pubic arch — Normally, the pubic arch is rounded and should accommodate the palmar aspect of two fingers. Configuration of the arch is more important than pubic angle. Diagonal conjugate — After the procedure, the fingers are now taken out . Pubic angle: The inferior pubic rami are defined and in female, the angle roughly corresponds to the fully abducted thumb and index fingers. In narrow angle, it roughly corresponds to the fully abducted middle and index fingers . Transverse diameter of the outlet (TDO) — It is measured by placing the knuckles of the first interphalangeal joints orknuckles of the clinched fist between the ischial tuberosities . Anteroposterior diameter of the outlet—The distance between the inferior margin of the symphysis pubis and the skin over the sacrococcygeal joint can be measured either with the method employed for diagonal conjugate or by external calipers.

Clinical assessment of the pelvis

Measurement of transverse diameter of the outlet and subpubic angle

X-ray pelvimetry is of limited value in the diagnosis of pelvic contraction or cephalopelvic disproportion. The other factors involved in successful vaginal delivery apart from pelvic capacity are the fetal size, presentation, position and the force of uterine contractions. X-ray pelvimetry cannot reliably predict the likelihood of vaginal delivery in breech presentation or in cases with previous cesarean section. X-ray pelvimetry is a poor predictor of pelvic adequacy and success of vaginal delivery. However, X-ray pelvimetry is useful in cases with fractured pelvis and for the important diameters which are inaccessible to clinical examination . Techniques: For complete evaluation of the pelvis, three views are taken — anteroposterior, lateral and outlet. But commonly, X-ray pelvimetry is restricted to only the erect lateral view (the femoral head and acetabular margins must be superimposed). Anteroposterior view can give the accurate measurement of the transverse diameter of the inlet and bispinous diameter.

Limitations of X-ray pelvimetry: The following are the prognostic significances of the successful outcome of labor: (1) Size and shape of the pelvis (2) Presentation and position of the head (3) Size of the head; (4) Moulding of the head (5) Give way of the pelvis; and (6) Force of uterine contractions. Out of these many unknown factors, X-ray pelvimetry can only identify one factor, i.e. size and shape of the pelvis. Thus, it can only supplement the clinical assessment of pelvis but cannot replace the clinical examination Hazards of X-ray pelvimetry includes radiation exposure to the mother and the fetus .With conventional X-ray pelvimetry radiation exposure to the gonads is about 885 millirad. So it is restricted to selected cases only. Computed Tomography (CT) involves less radiation exposure (44–425 millirad) and is easier to perform. Accuracy is greater than that of conventional X-ray pelvimetry . Magnetic Resonance Imaging (MRI) is more accurate to assess the bony pelvis. It is also helps in assessing the fetal size and maternal soft tissues involved in dystocia. It has got no radiation risk, hence biologically safe. It is expensive, requires more time and availability is limited. Ultrasonography is useful to measure the fetal head dimensions in the intrapartum phase. DISPROPORTION DEFINITION: Disproportion, in relation to the pelvis, is a state where the normal proportion between the size of fetus to the size of the pelvis is disturbed. The disparity in the relation between the head and the pelvis is called cephalopelvic disproportion. Disproportion may be either due to an average size baby with a small pelvis or due to a big baby with normal size pelvis (hydrocephalus) or due to a combination of both the factors. Pelvic inlet contraction is considered when the obstetric conjugate is < 10 cm or the greatest transverse diameter is < 12 cm or diagonal conjugate is < 11 cm. Contracted Midpelvis: Midpelvis is considered contracted when the sum of the inter-ischial spinous and posterior sagittal diameters of the mid pelvis (normal: 10.0 + 5 = 15.0 cm) is 13.0 cm or below. Contracted outlet is suspected when the inter ischial tuberous diameter is 8 cm or less. A contracted outlet is often associated with midpelvic contraction. Isolated outlet contraction is a rarity. Disproportion at the outlet may not give rise to severe dystocia, but may cause perineal tears. The head is pushed backwards as it cannot be accommodated beneath the symphysis pubis. It is more important to know whether the greatest diameter of the head passes through the different planes of the pelvis as featl head is the largest part that has to pass through the pelvis. So, identification of the cephalopelvic disproportion is more logical than to concentrate entirely on the measurements of a given pelvis, as the fetal head is the best pelvimeter. Thus,

disproportion may be limited to one or more planes. Absence of cephalopelvic disproportion at the brim usually, but not always, negates its presence at the midpelvic plane. On the other hand, isolated outlet contraction without midpelvic contraction is a rarity. Thus, a thorough assessment of the pelvis and identification of the presence and degree of cephalopelvic disproportion are to be noted while evaluating a case of contracted pelvis. DIAGNOSIS OF CEPHALOPELVIC DISPROPORTION (CPD) AT THE BRIM The presence and degree of cephalopelvic disproportion at the brim can be ascertained by the following: • Clinical — (a) Abdominal method; (b) Abdominovaginal (Muller-Munro Kerr) • Imaging pelvimetry • Cephalometry — (a) Ultrasound; (b) Magnetic Resonance Imaging; (c) X-ray Clinical: In multigravida, a previous history of spontaneous delivery of an average size baby, reasonably rules out contracted pelvis. But in a primigravida with nonengagement of the head even at labor, one should rule out disproportion. Abdominal method: The patient is placed in dorsal position with the thighs slightly flexed and separated. The head is grasped by the left hand. Two fingers (index and middle) of the right hand are placed above the symphysis pubis keeping the inner surface of the fingers in line with the anterior surface of the symphysis pubis to note the degree of overlapping, if any, when the head is pushed downwards and backwards Inferences: • The head can be pushed down in the pelvis without overlapping of the parietal bone on the symphysis pubis — no disproportion. • Head can be pushed down a little but there is slight overlapping of the parietal bone evidenced by touch on the under surface of the fingers (overlapping by 0.5 cm or 1/4” which is the thickness of the symphysis pubis) — moderate disproportion. • Head cannot be pushed down and instead the parietal bone overhangs the symphysis pubis displacing the fingers — severe disproportion. The abdominal method can be used as a screening procedure. At times, it is difficult to elicit due to deflexed head, thick abdominal wall, irritable uterus and high floating head.

Abdominal method of testing cephalopelvic disproportion

Abdominovaginal method (Muller-Munro Kerr): This bimanual method is superior to the abdominal method as the pelvic assessment can be done simultaneously. Muller introduced the method by placing the vaginal finger tips at the level of ischial spines to note the descent of the head. Munro Kerr added placement of the thumb over the symphysis pubis to note the degree of overlapping . Lower bowel is emptied preferably by enema. The patient is asked to empty the bladder. The patient is placed in lithotomy position and the internal examination is don...