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C H A P T E R 1 8 Physiology and care during the third stage of labour. Dr Areefa Albahri. Physiological processes.
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C H A P T E R 1 8Physiology and care during the third stage of labour DrAreefaAlbahri
Physiological processes The third stage can be defined as the period from the birth of the baby to complete expulsion of the placenta and membranes. Although labouris divided into three distinct component parts to aid comprehension, it should be viewed as one continuous process. The third stage usually lasts between 5 and 15 minutes, but any period up to 1 hour may be considered normal.
Separation and descent of the placenta • Mechanical factors During the second stage of labour, the uterine cavity progressively empties as the baby moves down, enabling the retraction process to accelerate. Retraction of the oblique uterine muscle fibers exerts pressure on the blood vessels so that blood does not drain back into the maternal system. The vessels during this process become tense and congested. With the next contraction the distended veins burst and a small amount of blood seeps in between the thin septa of the spongy layer and the placental surface, the relatively non-elastic placenta begins to detach from the uterine wall.
Once separation has occurred the uterus contracts strongly, forcing placenta and membranes to fall into the lower uterine segment (Fig. 18.4), and finally, into the vagina.
Haemostasis • The normal volume of blood flow through the placental site is 500–800 ml/min, but this is considerably reduced once the baby is born and the placental site on the uterine wall has diminished (Baldock and Dixon 2006). • At placental separation, blood flow has to be arrested or serious haemorrhage can occur. • four factors within the normalthat control bleeding & minimizing blood loss and preventing maternal morbidity or mortality:
Retraction of the oblique uterine muscle fibers in the upper uterine. • The presence of vigorous uterine contraction following separation – this brings the walls into apposition so that further pressure is exerted on the placental site. • The achievement of haemostasis–activation of the coagulation and fibrino-lytic systems during, and immediately following, placental separation.. • Breast-feeding – the release of oxytocin from the posterior pituitary in response to skin-to-skin contact between mother and baby, and the baby's nuzzling at the breast, causes uterine contractions.
Caring for a woman in the third stage of labour • The midwife's care of the mother should be based on an understanding of the normal physiological processes at work, including having access to as much information as possible about the woman's pregnancy and labour history. • Progress of the first and second stages of labour are likely to impact on management of the third stage of labour and should not be reviewed in isolation. • The midwife's actions can reduce the risks of haemorrhage,infection, retained placenta and shock. • A mother's ability to withstand complications in the third stage depends upon her general health and the avoidance of predisposing problems, such as anaemia, ketosis, exhaustion and prolonged hypotonic uterine action. • Detailed, accurate, documentation is extremely important in all aspects of care,
third stage management has two examples might be: where a woman requests • 1. expectant (physiological) management of the third stage of labour (EMTSL) • 2. active management (AMTSL),, clinical manager or the attending medical practitioner if any of the woman's requests are contrary to local guidelines.
Expectant (or physiological) care during the third stage of labour (EMTSL) In expectant management no routine actions (such as administration of a uterotonic drug, or clamping of the umbilical cord) are carried out. the following instructions for best practice when using EMTSL: • Maintain a calm, quiet, warm environment. • Use warmed sheets or blankets to wrap mother. • baby together, skin-to-skin close contact will stimulate oxytocin release, which may shorten the third stage and increase breast-feeding on discharge . • Maintain the woman in a comfortable, semi-upright position (at least a 45° angle) to encourage placental separation by maintaining a gentle downward weight.
Facilitate this time of parent–baby discovery and attachment by keeping quiet, observing from a distance and not interfering with the physiological processes. • Watch and wait. Take cues from the woman's behaviour; if she is alert and happy, examining the baby and talking, she is not bleeding excessively or in need of any intervention. • checking the woman's pulse if there is any anxiety in, for example, a prolonged third stage.
Observe Signs of placental separation: • Well contracted uterus. • A large ‘gush’ of blood may follow, indicating partial or complete separation of the placenta. It usually ceases after 10–20 • The cord may lengthen and/or the walls of the vulva may bulge as the placenta descends. • The midwife can palpate the placenta in the vagina by VE. • The uterus becomes hard, round and mobile
It is inadvisable to touch or manipulate the uterus at this stage, as this can prevent full contraction, disturb the fibrin mesh, and cause excessive bleeding. If there is concern that the uterus may be filling up with blood (a concealed haemorrhage), a gentle hand placed on the fundus will detect if there is a large, soft, uncontract uterus.
Birthing the placenta: • Gravity should be used during the birth of the placenta by encouraging a truly. • upright position: sitting on a birthing stool, standing up in the birthing pool or on the birthing mat, walking out to the toilet, sitting on the toilet, ect,,,,. It should be noted that such positions increase visible blood loss . • Maternal effort can be used. • The cord should be left unclamped until pulsation ceases or until after the birth of the placenta. • Any mild resuscitation of the baby can be done at the site of birth, with the benefit of continued oxygen flow to the baby through the umbilical cord.
If the placenta is definitely separated and is sitting just inside the vagina the midwife may ease gently on the cord to help lift out the placenta. This is not controlled cord traction as no force is used. • Controlled cord traction should NEVER be used in the absence of a well contracted uterus following uterotonic administration.
Trailing membranes should be teased out gently, by turning the placenta around and twisting them into a ‘rope’, thus stripping the ends gently from the uterine wall. • At any time, a uterotonicmay be administered to control haemorrhage, or if uterine tone is poor following placental birth. • It is preferable to withhold oxytocin until the placenta is delivered, if possible, to avoid the risk of a retained placenta when the uterus contracts strongly in response to the treatment.
This spontaneous process can take from 10 minutes to 1 hour to complete. If the placenta remains undelivered for a prolonged period, the risk of bleeding becomes greater because the uterus cannot contract down fully while the bulk of the placenta is in situ. • frequency of haemorrhage increased between 10 minutes and 40 minutes after the birth of the baby. • Early attachment of the baby to the breast may enhance these physiological changes by stimulating the reflex release of oxytocin.
Active management of the third stage of labour (AMTSL) • in active management includes the routine prophylactic administration of a uterotonic agent, either intravenously, intramuscularly or (occasionally) orally, as reducing the risk of postpartum haemorrhage. • undertaken in conjunction with clamping of the umbilical cord shortly after birth of the baby and delivery of the placenta by the use of controlled cord traction. • This would also be considered to be part of an active management policy, as would routine uterine massage following delivery of the placenta in some countries (Jangsten et al 2011), although there is no evidence to support this practice once an oxytocic has been given (Hofmeyer et al 2013).
Active management in the third stage is the policy of third stage labour management most widely practiced throughout the developed world.
Administration of uterotonics • Uterotonics(also known as oxytocics, or ecbolic), are drugs (e.g. Syntometrine,Syntocinon, ergometrine and prostaglandins) that stimulate the smooth muscle of the uterus to contract. • They may be administered with crowning of the baby's head, at the birth of the anterior shoulder of the baby, after the birth of the baby but prior to placental expulsion, or following the birth, or delivery, of the placenta and membranes. • In practice, one of the following uterotonic drugs is usually used.
Intravenous ergometrine 0.25–0.5 mg • This drug acts within 45 seconds, and is particularly useful in securing a rapid contraction where hypotonic uterine action results in haemorrhage. If a doctor is not present in such an emergency, a midwife may give the injection, if it is within his/her scope of practice. • it iscontraindicated where there is a history of hypertensive disorder or cardiac disease (Dyer et al 2010). • To decrease the chance of nausea and vomiting when the woman has had acaesarean section under epidural, it is advisable not to use ergometrine on its own (Balki and Carvalho 2005).
Combined ergometrine and oxytocin (a commonly used brand is Syntometrine) • A 1 ml ampoule contains 5 IU of oxytocin and 0.5 mg ergometrine and is administered byi.m. injection. • The oxytocin acts within min, and the ergometrine within 6–7 min. Their combined action results in a rapid uterine contraction. • It can be administered as the anterior shoulder of the baby is born, or after the birth of the baby. side-effects such as elevation of blood pressure, nausea and vomiting. • ‘Syntometrine should be avoided as a routine drug completely’.
CAUTION: No more than two doses of ergometrine 0.5 mg should be given, due to its side-effects.
Oxytocin • Oxytocin (a commonly used brand is Syntocinon) is a synthetic form of the natural oxytocin produced in the posterior pituitary, and is safe to use in a wider context than combined ergometrine/oxytocin agents. • It can be administered as an intravenous and or intramuscular injection. However, an intravenous bolus of oxytocin can cause profound, fatal hypotension, especially in the presence of cardiovascular compromise. • oxytocin is an effective uterotonic choice where routine prophylactic management of the third stage of labour is practised, more specifically in women who experience a blood loss exceeding 1000 ml.
Prostaglandins The use of prostaglandins for third stage management has up until now been more often associated with the treatment of postpartum haemorrhage than with prophylaxis. • Misoprostol (a prostaglandin E1 analogue) was first used to treat gastric ulcers, but then used as a uterotonic agent . • Misoprostol orally or sublingually (400–600 µg) appears to be a useful drug to prevent PPH, but is not as effective as Syntocinon, and has unpleasant side-effects, such as severe shivering, dairrhea, and higher temperature, both of which are transient but unacceptable to some women. • Even though the recommendation of the latest Cochrane review is that misoprostol should not replace other uterotonics, the authors suggest that it may be useful in circumstances where nothing else is available (Tunçalp et al 2012).
Clamping of the umbilical cord • Early clamping of the cord, as part of active management of the third stage of labour (AMTSL), is normally applied in the first 30 seconds to 3 minutes after birth, regardless of whether or not cord pulsation has ceased. It has been suggested that this practice may have the following effects:
It may reduce the volume of blood returning to the fetus by an amount between 75 and 125 ml, which is 30–40% of total potential blood volume. • It may prematurely interrupt the respiratory function of the placenta in maintaining O2 levels and combating acidosis in the early moments of life. • It may result in lower neonatal bilirubin levels, although the effect on the incidence of clinical jaundice is unclear
Venous pressure is further increased as retraction continues and may be sufficiently high to rupture surface placental vessels, thus facilitating the transfer of fetal cells into the maternal system; this may be a critical factor where the mother's blood group is Rhesus negative.
late clamping suggest that no action be taken until cord pulsation ceases or the placenta has been completely delivered, thus allowing the physiological processes to take place without intervention • Research has shown that when we delay cord clamping the neonate will receive up to 30% more of the fetal-placental blood volume than it would have with immediate cord clamping. • Benefits include: • a normal, healthy blood volume for the transition to life outside the womb. • a full count of red blood cells, stem cells and immune cells. • For the mother, delayed clamping keeps the mother-baby unit intact and can prevent complications with delivering the placenta.
There is growing evidence that delaying cord clamping improved iron status in infants up to 6 months post-birth . • Delayed cord clamping in preterm babies (until at least 30–120 seconds) is associated with babies requiring fewer transfusions, and having a lower risk of developing necrotizing enterocolitis or intraventricularhaemorrhage. • Delayed cord clamping may decrease the risk of feto-maternal transfusion, which is important in women with Rhesus-negative blood (Wiberg et al 2008).
clamp 3–4 cm clear of the abdominal wall, to avoid pinching the skin or clamping a portion of gut, which, in rare instances, may be in the cord. A greater length of cord is left when umbilical vessels are needed for transfusion, for example in preterm babies and cases of Rhesus haemolytic disease. The second clamp is placed closer to the placental end of the cord, with approximately 2–4 cm between them. The cord between the two clamps is then cut. The baby may then be placed on the mother's abdomen, put to the breast or be more closely examined on a warmed cot if resuscitation is required.
If the cord is clamped and cut soon after birth, the midwife should release the second clamp and drain blood from the maternal end of the cord to simulate placental–fetal transfusion, as this may reduce maternal blood loss up to 77 ml and shorten the third stage by up to 3 minutes (Soltani et al 2011).
Delivery of the placenta and membranes • Controlled cord traction (CCT) • Recent research has shown that this manoeuvre has no effect on severe haemorrhage (>1000 ml) and life, if any, effect on mild PPH (>500 ml) in both high and low income settings . • It does, however, shorten the third stage of labour by 6 minutes • If CCT is to be used successfully, the principles of placental separation described at the beginning of this chapter should be clearly understood., the midwife should check: • that a uterotonic drug has been administered • that it has been given time to act • that the uterus is well contracted • that counter-traction is applied • that signs of placental separation and descent are present.
As the placenta separates and falls into the lower uterine segment there is : • a small fresh blood loss • the cord lengthens • the fundus becomes rounder, smaller and more mobile as it rises in the abdomen above the level of the placenta. • It is important not to manipulate the uterus in any way as this may precipitate in coordinate action. • No further step should be taken until a strong contraction is palpable. If tension is applied to the umbilical cord without this contraction, uterine inversion may occur. This is an acute obstetric emergency with life-threatening implications for the mother.
Once the uterus is found to be contracted, one hand is placed above the level of the symphysispubis with the palm facing towards the umbilicus, exerting pressure in an upwards direction. This is counter-traction. The other hand, firmly grasping the cord, applies traction in a downward and backward direction following the line of the birth canal (Fig. 18.7). Some resistance may be felt but it is important to apply steady tension by pulling the cord firmly and maintaining the pressure. Jerky movements and force should be avoided. The aim is to complete the action as one continuous, smooth, controlled movement.
Is the timing of uterotonic administration, cord clamping and/or CCT clinically important in influencing the incidenceof PPH? • Although active management leads to reduced risk of PPH, it is important to establish which of the components of this package lead(s) to this reduction. • Whether oxytocin is administered before or after the placenta is expelled does not appear to make any significant difference to the incidence of PPH (blood loss >500 ml and >1000 ml), maternal hypotension, retained placenta, length of third stage, mean blood loss, maternal haemoglobin, need for maternal blood transfusion or therapeutic uterotonics(Soltani et al 2010).
Evidence for active versus expectant management • There is an increasing amount of appropriate, rigorously conducted research evidence available that suggests that the prophylactic administration of a uterotonic significantly reduces the • risk of PPH • a lower mean blood loss • fewer blood transfusions are required • a reduced need for therapeutic uterotonics. • Midwifery students should be given the opportunity to assist at births using EMTSL, to learn and develop their skills, as ‘knowledge of physiological management of the third stage of labour is considered a basic midwifery competency’ by the International Confederation of Midwives (ICM 2008).
Asepsis • The need for asepsis is even greater now than in the preceding stages of labour. • Laceration and bruising of the cervix, vagina, perineum and vulva provide a route for the entry of microorganisms. At the placental site, a raw surface provides an ideal medium for infection. • Strict attention to the prevention of infection is therefore vital.
Cord blood sampling • This may be required for a variety of conditions: • when the mother's blood group is Rhesus negative or if the mother's Rhesus type is unknown; • where a haemoglobinopathy is suspected (e.g. sickle cell disease); • ‘when there has been concern about the baby either in labour or immediately following birth’ (NICE 2007:231). The sample should be taken as soon as possible from the fetal surface of the placenta where the blood vessels are congested and easily visible. These may include the baby's blood group, Rhesus type, haemoglobin estimation, serum bilirubin level, cord blood analysis for acid base status, Coombs' test or electrophoresis. Maternal blood for Kleihauer testing can be taken upon completion of the third stage.
Completion of the third stage • Once the placenta has spontaneously birthed, or has been delivered, the midwife must first check that the uterus is well contracted and fresh blood loss is minimal. • Careful inspection of the perineum and lower vagina is important. • A strong light is directed onto the perineum in order to assess trauma accurately prior to instigating repair. • This should be carried out as gently as possible as the tissues are often bruised and oedematous. • If perineal suturing is required it should be carried out as expediently as possible to prevent unnecessary blood loss, increased risk of oedema at the site of trauma and perhaps unnecessary re-infiltration of additional local anaesthetics.
Blood loss estimation • Blood loss is difficult to measure and is frequently underestimated. • Account must be taken of blood that has soaked into linen and swabs as well as measurable fluid loss and clot formation. women can withstand perhaps a 1000–1500 ml blood loss. However, any further blood loss may not be tolerated so readily. Women who undergo elective caesarean section will for the most part have been adequately prepared. Women who undergo emergency caesarean section or vaginal birth who are dehydrated or anaemic may not withstand sudden large volumes of blood loss. • It was foubded that 20% of women lose >500 ml of blood after a vaginal birth. • Note: It should also be remembered that any amount of blood loss that causes a physical deterioration such as feeling faint, sudden onset of tachycardia, altered respirations or drop in blood pressure should be immediately investigated.
Examination of placenta and membranes • This should be performed as soon after birth , inspection must be carried out in order to make sure that no part of the placenta or membranes has been retained. The membranes are the most difficult to examine as they become torn during the birth or delivery and may be ragged. The placenta should then be laid on a flat surface and both placental surfaces minutely examined in a good light. The amnion should be peeled from the chorion right up to the umbilical cord, which allows the chorion to be fully viewed.
Immediate care It is advisable for mother and baby to remain in the midwife's care for at least 1 hour aher birth,. Much of this time will be spent in clearing up and completion of records but careful observation of mother and infant is very important. If an epidural catheter is in situ it is usually removed and checked at this time. Early physiological observations including ensuring a well-contracted uterus, assessment of vaginal blood loss and a gentle inspection of the genital tract to inspect for trauma should be undertaken (NICE 2007). • The woman should be encouraged to pass urine because a full bladder may impede uterine contraction. She may not actually feel an urge to do so, especially if she has passed urine immediately prior to giving birth or an effective epidural has been in progress, but she should be asked to try. Uterine contraction and blood loss should be checked on several occasions during this first hour. Once basic procedures to ensure the woman's and baby's safety and comfort have been completed, the woman may be offered a light meal such as tea and toast.
Most women intending to breastfeed will wish to put their babies to the breast during these early moments of contact. This is especially advantageous, as babies are usually very alert at this time and their sucking reflex is particularly strong. There is also evidence to suggest that women who breastfeed soon after birth successfully breastfeed for a longer period of time (Salariya et al 1979). • An additional benefit lies in the reflex release of oxytocin from the posterior lobe of the pituitary gland, which stimulates the uterus to contract. This may result in the mother experiencing a sudden fresh blood loss as the uterus empties and she should be pre-warned and reassured that it is a normal response. The desire to feed a newborn baby is a warm, loving and instinctive response. While breastfeeding should be actively encouraged, a formula feed should be available for those who do not wish to breastfeed.
Record-keeping • A complete and accurate documentation of the administration of all medicines, physical examination and observations, is the midwife's responsibility. • This should also include details of examination of the placenta, membranes and cord. • The volume of blood loss is particularly important. • This record not only provides information that may be critical in the future care of both mother and infant but is a legal document that may be used as evidence of the care given. • Signatures are therefore essential, It is usually the midwife who completes the birth notification form. Timely notification and referral may prevent delay in a woman receiving appropriate assistance should she need it.
Transfer from the birth room • The midwife is responsible for seeing that all observations are made and recorded prior to transfer of mother and baby to the postnatal ward, or home, or before the midwife leaves the home following the birth. • The postnatal ward midwife should verify these details prior to transfer of mother and baby. Following a domiciliary birth, the midwife should leave details of a telephone number where she may be contacted should the parents feel any cause for concern.
