Placental Separation 2w4h2x

INTRODUCTION

The third stage of labor refers to the interval from the delivery of the baby to the separation and expulsion of the placenta. The major complication associated with this period is postpartum hemorrhage (PPH), which is the most common cause of maternal morbidity and mortality in developing countries. Even in developed countries, although maternal mortality rates are much lower, PPH remains a major concern . It ranks just behind thromboembolic events and hypertensive disease as a common cause of maternal death in women whose pregnancies continue beyond 20 weeks. METHODS OF PLACENTAL SEPARATION Expectant management In this management the placental separation and its descent in to the vagina are allowed to occur spontaneously. Minimal assistance may be given for the placental expulsion if it need. Constant watch is mandatory and the patient should not be left alone If the mother is delivered in the lateral position, she should be changed to dorsal position to not features of placental separation and to assess the amount of blood loss PHYSIOLOGICAL PROCESSESS -The physiological processes occurring during the 3rd stage are a continuation of those forces/processes occurring during the 1st and 2nd stages of labour -Interplay of mechanical and haemostatic factors to separate and expel the placenta, and control bleeding from the placental site Separation and Descent of the Placenta -Baby born - marked reduction in size of uterus due to powerful contraction and retraction (ongoing) -Size of placental site therefore reduced (can be up to ½ before separation begins) -Inelastic placenta is squeezed by contraction Separation and Descent of the Placenta -Congested veins burst with next contraction 1

-Small amount of blood released (extravasated) causing villi to shear off from the spongy layer of deciduas -Placenta separates (at Layer of Nitabusch)-stripped from its attachment due to reduction in surface area of placental site as uterus shrinks -Placenta undermined, detached and propelled into lower uterine segment -Non-elastic placenta has detached from the shrinking uterine wall -Primary mechanism is the reduction in surface area of placental site as the uterus shrinks -Secondary mechanism is the formation of haematoma due to venous occlusion and vascular rupture in the placental bed caused by uterine contractions Methods of Placental Separation -Schultze Method : placenta normally separates in the centre and folds in on itself, peeling off the membranes as it descends into the lower part of uterus -Fetal surface appears at vulva with membranes trailing behind -Minimal visible blood loss as retroplacental clot contained within membranes (inverted sac) -Matthews Duncan Method : less commonly, separation starts at the lower edge of placenta (asymmetrical/lateral border separates) -Placenta slips down sideways and maternal surface appears first at vulva -Usually accompanied by PV bleeding – blood from placental site escapes immediately -No formn of retroplacental clotslower separation and more blood loss associated with it Signs of Separation and Descent -Once separation complete, upper uterine segment contracts strongly forcing placenta into lower segment and then into the vagina -Bleeding (Separation) -Uterus smaller, rounder, fundus rises and is more freely mobile (perched on top of placenta) (Descent) 2

Cord lengthens Control of Bleeding -Normal blood flow through site is 500-800 ml/minute (10-15% of cardiac output) Normal physiological processes are critical factors in minimising blood loss and protecting the woman -1. Powerful contraction/retraction of uterus especially action of interlacing muscle fibres (“living ligature”) which constrict blood vessels running through the myometrium 2. Pressure exerted on placental site by walls of contracted uterus (apposition – once placenta and membranes delivered) 3. Blood clotting mechanism (sinuses and torn vessels)

Active management of third stage Procedures: inj.ergometrine 0.25 mg or methergin 0.2 mg is given intravenously following birth of the anterior shoulder. If istered prior to this, there is chance of imprisonment of the shoulder behind the symphysis pubis. This is followed by slow delivery of the baby taking at least 2-3 minutes. The placenta is expected to be delivered following the delivery of the buttocks. If the placenta is not delivered instantaneously, it should be delivered for with by controlled cord traction technique after clamping the cord while the uterus still remains contracted. If the first attempt fails, another attempt is made after 2-3 minutes failing which another attempt is made at 10 minutes. If this still fails , manual removal is to be done. I f the istration is mistimed as might happen in a busy labour room, one should not be panicky but conduct the third stage with conventional watchful expectancy. CONCLUSION The third stage begins after the expulsion of the fetus and ends with expulsion of the placenta and membaranes. Its average duration is 15 minutes. The stage concerns with placental separation and expulsion. The separation is achieved by marked reduction the uterine surface area of the placental site following delivery due to retraction. The placenta being inelastic shearers its attachment through the deep spongy decidual layer. There are 2 ways of separation central and marginal.

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