Normal Labour

Case: A 24 year old G2P1, a booked case of your hospital comes to you in labour. She tells you that she has been having labour pain for almost 5 hours now.  On abdominal palpation, you can feel 3 strong uterine contractions every 10 mins. The head is engaged. On PS, cervix is 4cm dilated with effacement. On PV, the head is felt at “0” station. How will you manage the case now? 

What is labour? 

Expulsion of fetus through uterus after the age of viability

What is normal labour ?

• Vertex presentation
• Spontaneous onset of labour at term
• Natural termination through vagina
• Without any assistance 
• Without any complications

Onset of labour

• Fetus – Anterior pituitary and adrenal gland
• Placenta – Hormones
• Mother – Uterus, Hormone and Prostaglandins

At term- Increased release of ACTH from the Ant Pituitary

                                    ↓

Increased secretion of cortisol

                 ↓

Increased in oestrogen

                 ↓

Increased oxytocin receptors in the myometrium

                  

Increased prostaglandin synthesis

Prostaglandins

• Decidua
• Membranes
• Placenta
• Liquor

Diagnosis of onset of labour

• Painful intermittent uterine contractions 
• Show
• Dilatation of cervix
• Formation of bag of water

Characteristics of uterine contractions

• Intermittent
• Regular interval
• Relaxation in between
• Followed by retraction

Starts from cornua – descends down

Fundal dominance

Synchronous

Intra amniotic pressure rise to > 20mm Hg

1st stage – 40-50 mm Hg

2nd stage – 100-120 mm Hg 

Characteristics of cervical dilatation

• Progressive 1cm per hour in primi
• 1.5 cm per hour in multi
• Effacement – progressive shortening of cervix due to gradual merging up of upper part of cervix to the lower segment
• May occur before dilatation of cervix in primi
• Occurs together with dilatation during labour

Stages of labour

1st stage – Onset of labour to full dilatation of cervix = 10 cm

2nd stage- full dilatation of cervix to delivery of fetus

3rd stage- delivery of fetus to expulsion of placenta

Duration of labour

Total duration 

1st stage -  Primi 8-16 hrs (average 12 hrs)

                -  Multi 4- 8 hrs (average 6 hrs)

2nd stage- Primi 1-2 hrs

                - Multi 1 hr

3rd stage – 5 to 15 min  

Mechanism of labour

• Engagement
• Engaging diameter – sub-occipito-bregmatic (9.4 cm)
• Descent with flexion
• Internal rotation
• Crowning
• Extension
• Restitution and External rotation
• Delivery of trunk

Management of 1st stage of labour

1st stage – latent stage and active stage 

General care

Monitor labour

General care

• Support and care 
• Mobilization
• Nutrition
• Evacuation of bladder
• Antiseptic and asepsis

Monitor Progress of Labour

Maintain partograph

Components of partograph

• Mother’s identification
• Fetal heart rate
• Color of liquor and moulding
• Rate of cervical dilatation and descent of head
• Frequency in 10 min, duration and strength of uterine contraction
• Vitals = pulse, BP, Temp
• Oxytocin infusion
• Drugs and I/V fluids
• Urine for acetone, albumin and volume

Management of 2nd stage

• Position
• Bearing down during contraction
• Episiotomy need
• Support perineum
• Suction baby’s mouth and nose
• Keep the baby on mother’s abdomen
• Dry the baby by wiping
• Clamp and cut the cord
• Keep the baby warm
• Skin to skin contact

Active Management of 3rd stage

• Oxytocin 10 units I/M after delivery of fetus
• Controlled cord traction (CCT) 
• Uterine massage every 15 min for 2 hrs

Mechanism of control of bleeding

Signs of separation of placenta 

• Hardening of uterus
• Gush of blood per vaginum
• True lengthening of cord
• Rise of fundal height

Fetal skull

Landmark of Fetal skull 

Occiput:- is the occipital bone/external occipital protuberance.

Sinciput:- is the forehead region of fetal head.

Parietal eminences:- are the eminences of parietal bone on either side.

Mentum:- is the chin.

Vertical point:- is the center of sagittal suture.

Frontal point:- is the root of nose.

Sub occiput:- it is the junction fetal neck and Occiput.

Sub mentum:- it is the junction between neck and chin.

Bi parietal:- is the transverse distance between two parietal eminences.

Bi temporal :- is the distance between two lower end of coronal suture

SUTURES : SUTURES : 

Sagittal suture:- 

This lies in between two parietal bone.

Coronal suture:- 

This lies in between the frontal and parietal bone on either side.

Frontal suture:- 

This lies in between two frontal bone.

Lambdoid suture:- 

It lies in between the parietal and occipital bone on either side.

CLINICAL IMPORTANCE OF SUTURE

These suture permit gliding movement of one bone over  other during moulding of the head in the vertex presentation , as a result the diameter of the head get smaller so passage of head through the birth canal become easier.

Position of fontanelle and sagittal suture can identify attitude and position of vertex.

From the digital palpation of the sagittal suture during labour, degree of internal rotation and degree of moulding of the head can be noticed.

In deep transverse arrest, this sagittal suture lies transversely at the level of the ischial spines.

Area of skull

A. Vertex:- 

It is the quadrangular area bounded anteriorly by the bregma and coronal sutures behind by the lambda and the lambdoid sutures and laterally by the line passing through the parietal eminences.

B. Brow:- 

It  is an area bounded on one side by the anterior fontanelle and the coronal sutures and on the other side by the root of the nose and supra-orbital ridges of the either side.

C. Face:- 

It is an area bounded on one side by the root of the nose and the supra-orbital ridges and on the other by the junction of the floor of mouth with neck.

Diameter of skull

The engaging diameter of the fetal skull depends on the degree of the flexion of the presenting part. 

A. The antero-posterior diameter which may be engaged are:-

1.Sub-occipito bregmatic:-

It extends from the nape of the neck to the centre of anterior fontanelle.

Length:-9.5cm

Attitude:-complete flexion

Presentation:-Vertex.

Clinical importance:- 

Smallest diameter.

FETAL SKULL CHANGES IN LABOUR

Moulding:-It is the changes in shape of the head in vertex presentation during labour while passing through the resistant birth canal.

Mechanism:-  

1. Overlapping of cranial bones at the membranous joints due to compression of the engaging diameter of the head.

2. It is physiological, harmless and disappears within a few hours after birth.

GRADING

Grade 0:- the bones lies side by side having an intervening membrane.

Grade +:- the bone touching but not overlapping

Grade++:- overlapping but easily separated by pressure.

Grade+++:- fixed overlapping and cannot be separated.

CAPUT SUCCEDANEUM

It is localized area of edema on fetal scalp on vertex presentation due to pressure effect of dilating cervical ring and vaginal introitus.

Characteristics:-

It is physiological, present at birth and disappears within 24 hours.

It is soft, diffuse and pits on pressure.

No underlying skull bone fracture.

Cephalhematoma

It is a collection of blood between periosteum and skull bone which is limited by the periosteal attachments at the suture lines.

Characteristics:-

Appears after 12 hours of birth.

Limited by suture lines.

Tends to grow larger.

Disappears within 6-8  weeks.

It is circumscribed, soft and non pitting.

May be associated with skull bone fracture.

Treatment:- No treatment  required. The blood is absorbed and the swelling subside. 

DIFFERENCES 

Fetus in-utero

The lie 

Relationship between the long axis of the fetus and the long axis of the centralized uterus or maternal spine

Longitudinal

long axis of the fetus is aligned to the mother’s

this is the only NORMAL position

Transverse

long axis of the fetus is perpendicular to that of the mother’s

Oblique

long axis of the fetus is 0-90 degrees (or 90-180 degrees) to that of the mother’s

The presentation

The part of the fetus which occupies the lower pole of the uterus

Vertex

head down in the pelvis

Brow

Facial

Breech 

head is up in the uterine fundus and the buttock in the pelvis

Shoulder

Attitude

Relationship of fetal parts to each other:

Flexed 

Deflexed 

Extended

Denominator

Arbitrary bony fixed point on the presenting part

PRESENTATION

Vertex

Brow

Facial

Breech

Shoulder

ATTITUDE

Flexed

Deflexed (vertex)

Extended (vertex)

DENOMINATOR

Occiput

Frontal eminence

Mentum

Sacrum

Acromion

Flexed Vertex Presentation 8 Possibilities

LOL 

ROL

LOA

ROA

ROP

LOP 

OP

OA

Leopold’s Maneuver

Four-part process 

Aim

Determine the position of the baby  in utero 

Determine the expected presentation during labor and delivery 

Questions to ask yourself when performing the exam:

• Is the fundal height consistent with the fetal maturity?
• Is the lie longitudinal, transverse or oblique?
• Is the presentation cephalic or breech? 
• If cephalic, is the attitude vertex or facial? 
• Is the vertex engaged?

Preparation

Woman is supine, head slightly elevated and knees slightly flexed

If the doctor is R handed, stand at the woman’s R side facing her for the first 3 steps, then turn and face her feet for the last step (L handed, left side).

First Maneuver

What part is in the fundus?

Facing the mother, palpate the fundus with both hands

Assess for shape, size, consistency and mobility

Fetal head: firm, hard, and round

Detectable by ballotement

Buttocks/breech: softer and has bony prominences

Second Maneuver

Determine position of the back.

Still facing the mother, place both palms on the abdomen

Hold R hand still and with deep but gentle pressure, use L hand to feel for the firm, smooth back 

Repeat using opposite hands

Once you’ve located the back, confirm your findings by palpating the fetal extremities on the opposite side  (“lumpy”)

Third Maneuver

Determine what part is lying

above the inlet.

Gently grasp just above symphisis pubis with the thumb and fingers of the R hand 

Confirm presenting part (opposite of what’s in the fundus)

Head will feel firm

Buttocks will feel softer and irregular

If it’s not engaged, it may be gently pushed back and forth

Proceed to the 4th step if it’s not engaged…

Fourth Maneuver

Flexed/Deflexed/Extended?

Turn to face the woman’s feet

Move fingers of both hands gently down the sides of the abdomen towards the pubis 

Palpate for the cephalic prominence (vertex)

Prominence on the same side as the small parts suggests that the head is flexed (optimum)

Prominence on the same side as the back suggests that the head is extended

Using a Fetoscope

Fetal heart Rate (FHR) can be determined by use of:

Fetoscope 

specifically designed instruments 

Clinical stethescope

Electronic Doppler

Doppler Method

Employs a continuous ultrasound

Can detect the fetal heart at 10-12 weeks’ gestation

Amplifiers allow both the practitioner and parents to hear

Fetoscope

Can pick up the fetal heart rate at 17-19 weeks’ gestation

Fetal heart tones are best heard over the baby’s back

Used in conjunction with Leopold’s maneuver

Auscultation may be difficult if

Mother is overweight

Placenta is in the front of the uterus

*Always easier in later stages of the pregnancy

Where will you hear the FHTs?

Fetal Physiology

Consists of :                            

Fetal blood

Pulmonary system

Immune system

Skin 

Nervous system

Gastro-intestinal  system

Urinary system

Endocrine glands

Cardiovascular

Fetal blood

Haematopoesis:

1st fetal blood cells  : Day 14 embryo : in yolk sac

Next, major site is liver: 6th wk embryo  : (hence, enlarged liver) & spleen (lesser extent)

Finally, bone marrow starts to produce RBC:16 wks

By 26 wks :  bone marrow is the predominant source of RBC

As the fetus grows, volume of blood in fetoplacental circulation increases.

       At term, 125 ml/kg fetal wt.

Hb in the fetal blood also rises.

       At term, Hb  18 g/dl. Why ? Enhances    the transfer of O2 across placenta.

Fetal RBC has shorter lifespan.

       At term, 90 days.

Hb in fetus:

Mostly fetal haemoglobin (HbF):    α2 γ2  instead of adult Hb A (α2 β2 ) and Hb A2 (α2 δ2 )

   

     10 – 28 wks    90 % of fetal Hb is HbF

     28 – 34 wks    HbF: HbA= 80:20

     6 mths age     HbF = 1 %

HbF vs HbA

     HbF has greater O2 binding capacity and it is resistant to denaturation by acid/alkali.

Fetal Haemoglobin

HbF  has higher affinity for O2 than adult in vivo due to a lower sensitivity to DPG (2,3 diphosphoglyceric acid)

Partial pressure of O2 in fetal circulation is low (92.7KPa) but this is compensated for by high Hb concentration and greater oxygen affinity

CVS

Differences (fetal vs adult circulation):

Major portion of Rt ventricular output bypasses the lungs coz fetal blood does not need to enter pulmonary vasculature

Oxygenation occurs in the placenta

Right & Left ventricles work in parallel ,rather than in series

Heart, brain & upper body receive blood from left ventricle ; placenta & lower body receive blood from both right & left ventricles

Presence of shunts:

         1. Ductus Venosus

         2. Foramen ovale

         3. ductus arteriosus

Fetal Circulation

Fetal blood pathway

Placenta  ----   umbilical vein 

----

      ductus      venosus  

----

        IVC 

----

      right atrium  

----

      foramen ovale  

----

      left atrium  

----

       left      ventricle   

----

       ascending aorta

•    coronary/cerebral arteries       SVC      right atrium       right ventricle       pulmonary artery        ductus arteriosus       descending aorta        umbilical artery      placenta

After birth, constriction/collapse of:

 umbilical arteries: instantaneous functional closure / actual obliteration takes 2-3 mths. Distal part – form lateral umbilical ligament. Proximal part – remain as superior vesical arteries

Umbilical veins: closure a little later than arteries. Forms ligamentum teres.

ductus arteriosus: functional closure soon after pulmonary circn is established. Anatomical obliteration takes 1-3 mths. Forms ligamentum arteriosum.

foramen ovale: functional closure soon after birth, anatomical closure in 1 yr.

ductus venosum: forms ligamentum venosum

Incidence of closure of fetal channels

Fetal circulatory response to hypoxia

• Heart rate falls
• Resistance in the umbilical artery increases
• Resistance in the middle cerebral artery decreases thus protecting flow to the fetal brain
• Blood flow increased to heart and adrenals
• Blood flow reduced to kidneys producing oligohydramnios (reduced volume of amniotic fluid)

Control of Fetal Heart Rate

Control of FHR is complex.

It is subject to modulating influences such as catecholamines and baroreceptors.

These influences generally act on FHR via the autonomic nervous system.

Parasympathetic tone dominates

Fetal Heart rates (FHR):

-20 weeks 155/minute

-30 weeks 144minute

-Term 140/min

FHR decreases in response to hypoxia

Fetal  Lung and Breathing

Development consist of

Pseudoglandular stage: 5-16 w

Canalicular stage: 16-25 w

Terminal sac stage: type II cells begin to produce surfactant 

At birth only 15% of adult alveoli are present in lungs       continue to grow up to 8 years

20 wks: full differentiation of capillary & canalicular elements of fetal lung

24 wks: alveoli develop, surfactant appear.

   Lung alveoli lined by surfactant (a group of phospholipids). 

   Prevents collapse of small alveoli during expiration by lowering surface tension

   Synthesized by type 2 alveolar cells ( 10 % of lung parenchyma)

   Lecithin ( phosphatidyl choline): main (80%)

Increased lecithin production :

Cortisol

Growth restriction

Prolonged rupture of membranes

Delayed lecithin formation in:

diabetes 

Phosphatidyl glycerol is more predictive of RDS esp in diabetic fetus.

Surfactant:

Composition: 90% lipids, 10% proteins

Phosphatidylcholine (lecithins):

                  DPPC: active component(50%)

                  PG: second(8-15%)

At birth,with first breath, an air to tissue interface is produced in the alveolus. Surfactant spreads to line alveolus to prevent collapse during expiration

Glucocorticoids and Surfactant :

Accelerate type 2 alveolar cell development

Accelerate surfactant synthesis

Accelerate lung structural maturation

Glucocorticoids play essential role in maturation of many fetal organs but excess amounts reduce fetal growth

Fetal breathing: 

Numerous but intermittent fetal breathing

   movements occur in utero especially during 

   sleep ( lung maturation).

Immune system

8 wks:  lymphocytes appear

Mid 2nd trimester: all phagocytic cells, T & B cells, complement

 Fetus consists almost totally of maternal IgG (transferred across placenta).

           16 wks: Maternal IgG transfer begins & increases

            Last 4 wks: bulk of IgG acquired.

            Hence, preterm :  less IgG

            Newborns produce IgG slowly & adult values are   reached only after 3 yrs.

IgM & IgA: very little is produced by fetus.

           not transferred across placenta.

          

General immunological defences:

1.Amniotic fluid (lysosomes, IgG)

2.Placenta (lymphoid cells, phagocytes, barrier)

3.Liver ( granulocytes)

Skin

16 wks: lanugo appears but disappears near term

1 month gestation till birth: skin thickness progressively increases

20 wks:  stratum corneum  distinct

Last wks: skin covered by vernix caseosa

                   desquamated skin cells

                   rich in cholesterol and glycogen

Preterm babies

• No vernix & thin skin ie, larger insensible loss

• Deficient brown fat

• Delayed development of sweat glands

Alimentary system & energy stores

• 10 wks: Swallowing reflex develops & gradually matures. Continuously and increasingly swallows amniotic fluid

• 2nd trimester:  Peristalsis in intestines

• Term : Large bowel is filled with meconium

    

• But defaecation in utero (meconium in amniotic fluid) unusual unless fetal anoxia

Intestinal villi well developed by 19weeks

• Gut development important for amniotic fluid

    homeostasis; (fetus swallows amniotic fluid

    from 12 weeks and amniotic fluid contains

    hormones and growth factors that stimulate

    gut development)

• Gastrin, motilin and somatostatin regulate

    growth and development      present in gut by 13

    weeks         matures by 24 weeks

• Digestive enzymes eg disaccharidases

    present by 9-10 weeks maturity at term

Meconium: 

Lanugo, vernix, scalp hair, epithelial cells from skin, mucus, exfoliated intestinal epithelium, intestinal juices

    

Liver:

Reduced capacity for conjugation of bilirubin esp. in preterm

Preterm infants:

Virtually no fat, so severely reduced ability to withstand starvation

Incompletely developed alimentary system

Poor and unsustained sucking ability

Uncoordinated swallowing mechanism

Delayed gastric emptying

Poor absorption of carbohydrates/fat/other nutrients

Kidney & urinary tract

• Urine usu found in UB of even small fetuses

• Fetal urine  gives rise to much of amniotic fluid. 

   (protein-free & sugar-free hypotonic ultrafiltrate of fetal plasma)

       12 wks:  urine production starts

       32 wks:  12 ml per hour

       40 wks:   38 ml per hour 

• 36 wks: nephrogenesis complete

   But maturation of excretory & concentrating ability of fetal kidneys is gradual

   Preterm: immature, so abnormal

Amniotic fluid

Source:

• Early pregnancy: ultrafiltrate of maternal plasma
• 10 wks: transudate of fetal serum via skin & umbilical cord
•  After 20 wks: mainly fetal urine ( as cornification of fetal skin, impermeable to water).

    Pulmonary fluid and fluid filtering through  placenta contribute little.

• AF volume:

        Varies at each week of gestation. 

        Volume increases with increasing    gestation.

        10 wks: 30 ml

        20 wks: 300 ml

        30 wks: 600 ml

        38 wks: 1000 ml

        40 wks:  800 ml

        42 wks:  350 ml

Functions of AF:

• Cushions fetus: Protect fetus from mechanical injury
• Permits movements of fetus while preventing limb contracture
• Prevents adhesions between fetus & amnion
• Maintains temperature
• Minimal nutritive function
• Permit fetal lung development--  2 way movements of fluid into fetal bronchioles
•    Absence of AF in 2nd trimester:  pulmonary hypoplasia
• Promotes growth & differentiation of GI tract 

• Renal agenesis, cystic kidney, IUGR ----oligohydramnios----reduced contribution of fluid into amniotic sac ----- major alterations in AF volume.

• Anencephaly, oesophageal atresia, duodenal atresia ----- polyhydramnios----- reduced removal of fluid

Fetal behaviour

• 18 wk: first fetal movements (quickening) perceived in primipara

    Several wks earlier in multipara

• Formal counting of fetal movements (screening)

Reduced or Absent in 

• Chronic hypoxia & growth failure
• fetal death

• Spinal cord extends along entire length of vertebral column in embryo, but after that, it grows more slowly.

    By 24 wks:  spinal cord extends to S1

    At birth:  L3

    In adults:  L1

• Myelination of spinal cord:  starts mid-preg
• 10 wks: swallowing
• 14-16 wks: respiration evident
• After 24 wks: ability to suck
• 24-25 wks: can hear some sounds in utero
• 28 wks: sensitive to light

Fetal endocrinology

• 10 wks: GH, ACTH, PRL , TSH produced by fetal pituitary
• 1st trimester: Vasopressin, oxytocin from posterior pituitary
• Fetal adrenal: hypertrophy of reticular zone (site of synthesis of DHEA-dehydroepiandrosterone). This zone is absent in anencephaly. Adrenal medulla produces catecholamines.
• 11 wks: Fetal thyroid produces small amount thyroxine

• Fetal ovaries remain inactive

• Fetal testicles mediate development of male reproductive structures

• 12 wks: fetal pancreas secrete insulin

PLACENTA AND FETAL MEMBRANES

PLACENTA

• Development
• Gross anatomy
• Structures
• Functions
• Abnormalities

DEVELOPMENT

1.Chorionic frondosum- fetal part the major component

2.Decidua basalis- maternal part the minor component

Begins at 6th weeks of gestation

Ends at 12th weeks of gestation

Anatomy

• Normally situated at or near fundus of uterus
• Shape- discoid
• Size- 15*20 cms, 2.5cm in thickness in centre
• 500gms in weight
• Two surfaces

1.Fetal- smooth, amniotic membrane, cord insertion and branching vessels.

2.Maternal- irregular,15-20 cotyledons,

Fetal surface

Maternal surface

Structure

Functions

1. Nutrition
2. Respiration
3. Excretion
4. Barrier
5. Hormonal- CRH, GnRH, TRH, GHRH, ACTH, hCG, hPL, hCT
6. Immunological- placental hormones, proteins(SP1), early pregnancy factor(EPF), steroids and hCG

Abnormal placenta

One or more smaller lobes of placenta placed at varying distances from placental margin.

Smaller chorionic plate than basal plate.

Cord Abnormalities

The cord is attached to the membranes.

The cord is attached to the margin of the placenta.

FETAL MEMBRANES

• CONSISTS OF 2 LAYERS

CHORION

AMNION

FUNCTIONS OF MEMBRANES

1.PRODUCES AMNIOTIC FLUID

2.PREVENTS FETUS FROM INFECTIONS

3.HELPS IN CERVICAL DILATION IN LABOR

4.PRODUCES PGE2, PGF2alpha