Normal labour
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Normal labour






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Normal labour Presentation Transcript

  • 1.  DefinitionSeries of events that take place in the genitalorgans in an effort to expel the viable products ofconception out of the womb through the vaginainto the outer world is called labour
  • 2.  Labour is normal when a full_term fetuspresenting by the vertex is expelled by naturalefforts, within a period of 24 hours. It should fulfil the folloing criteria;1.Spontaneous in onset and at term2.With vertex presentation .3.Without undue prolongation.4.Natural termination with minimal aids.5.Without having any complications affectingthe health of the mother and/or the baby.
  • 3. (1) Uterine distension;Stretching effect on the myometrium by the growing fetus andliquor amnii.Uterine stretch increases : gap junction protiens. receptors for oxytocin. specific contraction associated protions-(CAPS).(2) Fetoplacental contribution;Cascade of events activate fetal HPA axis prior to onsetof labour→increased CRH→increased release of ACTH→fetaladrenals→increased cortisol secretion →acclerated productionof oestrogen and prostaglandins from the placenta.
  • 4. 3. Oestrogen; increases the release of oxytocin from maternalpitutary. promotes the synthesis of myometrial receptors foroxytocin, prostaglandins and increase in gapjunctions. accelerates lysosomal disintegration in thedecidual and amnion cells resulting in increasedPGF2 synthesis. stimulates the synthesis of myometrial contractileprotein, increases the exitability of the myometrial cellmembranes
  • 5. 4.Progesterone:-Increased fetal production of DHEA-S andcortisol inhibits the conversion of fetal pregnenoloneto progesterone.Progesterone levels therefore fallbefore labour.5. Prostaglandins: These initiates and maintains the labour. Sites of synthesis-amnion,chorion,decidualcells,myometrium. Synthesis is triggered by_rise in oestrogenlevel,glucocorticosteroids,mechanical stretchingin late pregnancy,increase incytokines,infection,vaginal examination.they alsoenhance gap junction formation.
  • 6. 5. Oxytocin and myometrial oxytocin receptors;(a) Large number of oxytocin receptors are presentin fundus compared to lower segment of cervix.(b) Receptor number increases maximum duringlabour.(c) Receptor sensitivity increases .(d) Oxytocin stimulate synthesis and release of PGs.6. Neurologic factor:-Although labour may start in denervateduterus ,it may also be initiated through nervepathways.oestrogen causing the α receptors andprogesterone the β receptors to functionpredominantly.
  • 7. It consists of Actin Myosin ATP Myosin light chain kinase Calcium
  • 8. Intracellular calcium↓Calmodulin calcium↓MLCK↓phosphorylatedmyosin+actin↓Myometrial contractionDecrease of intracellularcalcium.↓Dephosphorylation ofmyosin light chain↓Inactivation of MLCK↓Myometrial relaxation.
  • 9.  Found more in primi. Appears prior to onset of true labour pain. Probably due to stretching of the cervix andlower uterine segment due to irritation ofganglia.
  • 10. This may begin 2 to 3 weeks before the onset oftrue labour in primi and a few days before inmultiparae.The features are;1. LIGHTENING.Few weeks prior to onset of labour ,thepresenting part sinks into true pelvis,due to activepulling up of the lower pole of uterus around thepresenting part.This diminishes the fundal height andminimises the pressure on diaphragm.Therebymother experiences relief.As it rules outCEPHALOPELVIC DISPROPORTION ,it is a“WELCOME SIGN”
  • 11. 2.CERVICAL CHANGES:Cervix become RIPE few days prior tolabour.RIPE cervix is less than 1.5cm inlength,admits a finger easily and is dilatable.
  • 12. - it is characterised by Uterine contractions at regular intervals Frequency of contractions increased gradually Intensity and duration of contractions increasedprogressively Associated with SHOW Formation of bag of forewaters Progressive effacement and dilation of the cervix Decent of the presenting part Not relieved by enema or sedative
  • 13. False labour pains are Dull in nature Confined to lower abdomen and groin Not associated with hardening of the uterus They have no other features of true labour pains Relieved by enema and sedativeLabour pain Throughout pregnancy, painless BRAXTON HICKScontractions with simultaneous hardening of theuterus occur. These contractions change their character, becomemore powerful, intermittent associated with painand felt in front of the abdomen or radiating towerdsthe thighs
  • 14.  Show Expulsion of cervical mucus plug mixed with blood iscalled show With onset of labour, there is profuse cervicalsecretion .simultaneously, there is slight oozing ofblood from the rupture of capillary vessels of thecervix and from the raw decidual surface. Dilation of internal os With the onset of labour pain, the cervical canalbegins to dilate more in the upper part than in thelower, the former being accompanied bycorresponding stretching of the lower uterinesegments.
  • 15.  Formation of bag of water Due to stretching of the lower uterine segment,themembranes are detached easily because of its looseattachment to poorly formed decidua. With the dilatation of the cervical canal , the lowerpole of the fetal membrane become unsupported andtends to bulge into the cervical canal. As it contains liquor which has passed below thepresenting part,it is called “bag of water”
  • 16.  During pregnancy there is markedhypertrophy and hyperplasia of the uterinemuscle. At term the length of the uterus measuresabout 35cm.UTERINE CONTRACTION IN LABOUR: Throughout pregnancy there is irregularinvoluntary spasmodic uterine contractionsand are painless{BRAXTON HICKS}and haveno effect on cervix dilatation.
  • 17.  Pacemaker of uterine contraction _is situated in theTUBAL OSTIA from where waves of contractionsspread downwards. Good synchronisation of the contraction waves fromboth halves of the uterus. there is fundal dominance with gradual diminishingcontraction wave through midzone. waves of contraction follow a regular pattern. intra_amniotic pressure rises beyond 20mm hg duringuterine contraction . good relaxation occurs in between contraction to bringdown intra_amniotic pressure to less than 8mmhg.contraction of fundus lasts longer than that ofmidzone.
  • 18.  During contration , uterus becomes hard &pushed anteriorly to make long axis of uterusin line with that of pelvis.PROBABLE CAUSES OF PAIN: myometrial hypoxia during contraction. stretching of peritonium over the fundus. stretching of the cervix during dilation. compression of nerve ganglion. Pain of uterine contraction distributed alongT10 toL1 , whereas pain of cervical dilatationis refered to back through the sacral plexus.
  • 19. Tonus: The intrauterine presssure in betweencontractions.tonus during pregnancy_2-3mmhg & tonus during labour is 8-10mm hg. Factors which govern tonus- contractility of uterine muscles. intraabdominal pressure. overdistension of uterus as in twins &hydromnios.
  • 20. INTENSITY: It discribes the uterine systole. Intensity gradually increases with advancement oflabour & becomes maximum during second stage. Intrauterine pressure- First stage-40 to 50 mm hg. second stage-100 to 120 mm hg. third stage-inspite of diminished pain the pressureremains same as second stage, due to lack ofstretching effect.
  • 21. DURATION: In the first stage ,contraction lasts for 30 secsbut gradually increase in duration withprogress of labour.FREQUENCY: In early stage , the contractions come atintervals of 10 to15 minutes.but the intervalgradually shorten with advancement of labouri.e,every 2-3 minutes.
  • 22. RETRACTION: Retraction is a phenomenon of the uterus inlabour in which the muscle fibres arepermanently shortened. Unlike other muscles of the body,the uterinemuscles have this property to becomeSHORTENED ONCE FOR ALL.CONTRACTION is temporary reduction inlength of fibres, which attain their full lengthduring relaxation.In contrast, RETRACTIONresults in permanent shortening once & for all.
  • 23. EFFECTS OF RETRACTION IN NORMALLABOUR: Essential property in the formation of loweruterine segment & dilatation &effacement ofcervix. to maintain the advancement of presenting part& to help in ultimate expulsion of the fetus. to reduce the surface area of the uterusfavouring separation of placenta. effective haemostasis after the separation ofplacenta.