Maternal Care: Monitoring the condition of the fetus during the first stage of labour

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Maternal Care addresses all the common and important problems that occur during pregnancy, labour, delivery and the puerperium. It covers: the antenatal and postnatal care of healthy women with normal …

Maternal Care addresses all the common and important problems that occur during pregnancy, labour, delivery and the puerperium. It covers: the antenatal and postnatal care of healthy women with normal pregnancies, monitoring and managing the progress of labour, specific medical problems during pregnancy, labour and the puerperium, family planning, regionalised perinatal care

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  • 1. 7 Monitoring the condition of the fetus during the first stage of labourBefore you begin this unit, please take the MONITORING THE FETUScorresponding test at the end of the book toassess your knowledge of the subject matter. Youshould redo the test after you’ve worked through 7-1 Why should you monitorthe unit, to evaluate what you have learned. the fetus during labour? It is essential to monitor the fetus during Objectives labour in order to assess how it responds to the stresses of labour. The stress of a normal labour usually has no effect on a healthy fetus. When you have completed this unit you should be able to: 7-2 What may stress the • Monitor the condition of the fetus fetus during labour? during labour. 1. Compression of the fetal head during • Record the findings on the partogram. contractions. • Understand the significance of the 2. A decrease in the supply of oxygen to the findings. fetus. • Understand the causes and signs of fetal 7-3 How does head compression distress. stress the fetus? • Interpret the significance of different fetal heart rate patterns and meconium- During uterine contractions compression of the fetal skull causes vagal stimulation which stained liquor. slows the fetal heart rate. Head compression • Manage any abnormalities which are usually does not harm the fetus. However, detected. with a long labour due to cephalopelvic disproportion, the fetal head may be severely compressed. This may result in fetal distress.
  • 2. MONITORING THE CONDITION OF THE FETUS DURING THE FIRST STAGE OF LABOUR 1417-4 What may reduce the supply However, contractions may reduce the oxygenof oxygen to the fetus? supply to the fetus when:1. Uterine contractions: Uterine contractions 1. There is placental insufficiency. are the commonest cause of a decrease 2. The contractions are prolonged or very in the oxygen supply to the fetus during frequent. labour. 3. There is compression of the umbilical cord.2. Reduced blood flow through the placenta: The placenta may fail to provide the fetus 7-7 How does the fetus respond with enough oxygen and nutrition due to a lack of oxygen? to a decrease in the blood flow through the placenta, i.e. placental insufficiency. A reduction in the normal supply of oxygen to Patients with pre-eclampsia have poorly the fetus causes fetal hypoxia. This is a lack of formed spiral arteries that provide oxygen in the cells of the fetus. If the hypoxia maternal blood to the placenta. This can is mild the fetus will be able to compensate also be caused by narrowing of the uterine and, therefore, show no response. However, blood vessels due to maternal smoking. severe fetal hypoxia will result in fetal distress.3. Abruptio placentae: Part or all of the Severe, prolonged hypoxia will eventually placenta stops functioning because it result in fetal death. is separated from the uterine wall by a retroplacental haemorrhage. As a result, 7-8 How is fetal distress recognised the fetus does not receive enough oxygen. during labour?4. Cord prolapse or compression: This stops Fetal distress caused by a lack of oxygen results the transport of oxygen from the placenta in a decrease in the fetal heart rate. to the fetus. NOTE The fetus responds to hypoxia with a bradycardia to conserve oxygen. In addition, Uterine contractions are the commonest cause blood is shunted away from less important of a decreased oxygen supply to the fetus during organs, such as the gut and kidney, to essential labour. organs, such as the brain and the heart. This may cause ischaemic damage to the gut and kidneys, and intraventricular haemorrhage7-5 How do contractions reduce the in the brain. Severe hypoxia will eventuallysupply of oxygen to the fetus? cause a decreased cardiac output leading to myocardial and cerebral ischaemia. HypoxiaUterine contractions may: also results in anaerobic metabolism which1. Reduce the maternal blood flow to the causes fetal acidosis (a low blood pH). placenta due to the increase in intra- uterine pressure. 7-9 How do you assess the condition2. Compress the umbilical cord. of the fetus during labour? Two observations are used:7-6 When do uterine contractions reducethe supply of oxygen to the fetus? 1. The fetal heart rate pattern. 2. The presence or absence of meconium inUsually uterine contractions do not reduce the liquor.the supply of oxygen to the fetus, as there is anadequate store of oxygen in the placental bloodto meet the fetal needs during the contraction.Normal contractions in labour do not affectthe healthy fetus with a normally functioningplacenta, and, therefore, are not dangerous.
  • 3. 142 MATERNAL CAREFETAL HEART RATE 7-12 How often should you monitor the fetal heart rate?PATTERNS 1. For low-risk patients who have had normal observations on admission:7-10 What devices can be used to • Two-hourly during the latent phase ofmonitor the fetal heart rate? labour. • Half-hourly during the active phase ofAny one of the following three pieces of labour.equipment: Patients with a high risk of fetal distress1. A fetal stethoscope. should have their observations done more2. A ‘doptone’ (Doppler ultrasound fetal heart frequently. rate monitor). 2. Intermediate-risk patients, high-3. A cardiotocograph (CTG machine). risk patients, patients with abnormal observations on admission, and patientsIn most low-risk labours the fetal heart rate with meconium-stained liquor need morecan be determined adequately using a fetal frequent recording of the fetal heart rate:stethoscope. However, a doptone is helpful • Hourly during the latent phase of labour.if there is difficulty hearing the fetal heart, • Half-hourly during the active phase ofespecially if intra-uterine death is suspected. labour.If available, a doptone is the preferred • At least every 15 minutes if fetalmethod in primary-care clinics and hospitals. distress is suspected.Cardiotocograph is not needed in mostlabours but is an important and accuratemethod of monitoring the fetal heart in high- 7-13 What features of the fetalrisk pregnancies. heart rate pattern should you always assess during labour? There are two features that should always be A doptone is the preferred method in primary- assessed: care clinics and hospitals. 1. The baseline fetal heart rate: This is the heart rate between contractions.7-11 How should you monitor 2. The presence or absence of decelerations: Ifthe fetal heart rate? present, the relation of the deceleration toBecause uterine contractions may decrease the contraction must be determined:the maternal blood flow to the placenta, and • Decelerations that occur only during athereby cause a reduced supply of oxygen to contraction (i.e. early decelerations).the fetus, it is essential that the fetal heart rate • Decelerations that occur duringshould be monitored during a contraction. In and after a deceleration (i.e. latepractice, this means that the fetal heart pattern decelerations).must be checked before, during and after the • Decelerations that have no fixedcontraction. A comment on the fetal heart relation to contractions (i.e. variablerate, without knowing what happens during decelerations).and after a contraction, is almost valueless. NOTE In addition, the variability of the fetal heart rate can also be evaluated if a cardiotocograph The fetal heart rate must be assessed before, is available. Good variability gives a spiky trace during, and after a contraction. while poor variability gives a flat trace.
  • 4. MONITORING THE CONDITION OF THE FETUS DURING THE FIRST STAGE OF LABOUR 1437-14 What fetal heart rate patterns can minute gives a flat baseline (a flat trace), whichbe recognised with a fetal stethoscope? suggest fetal distress. However, a flat baseline may also occur if the fetus is asleep or as a result1. Normal. of the administration of analgesics (pethidine,2. Early deceleration. morphine) or sedatives (phenobarbitone).3. Late deceleration.4. Variable deceleration. 7-15 What is a normal fetal5. Baseline tachycardia. heart rate pattern?6. Baseline bradycardia. 1. No decelerations during or afterThese fetal heart rate patterns (with the contractions.exception of variable decelerations) can 2. A baseline rate of 100–160 beats per minute.be easily recognised with a stethoscopeor doptone. However, cardiotocograph 7-16 What are early decelerations?recordings (figures 7-1, 7-2 and 7-3) areuseful in learning to recognise the differences Early decelerations are characterised by abetween the three types of deceleration. slowing of the fetal heart rate starting at the beginning of the contraction, and returningIt is common to get a combination of to normal by the end of the contraction. Earlypatterns, e.g. a baseline bradycardia with late decelerations are usually due to compressiondecelerations. It is also common to get one of the fetal head with a resultant increase inpattern changing to another pattern with vagal stimulation, which causes the heart ratetime, e.g. early decelerations becoming late to slow during the contraction.decelerations. NOTE Variability is assessed with a CTG. The 7-17 What is the significance variation in the fetal heart normally exceeds five of early decelerations? beats or more per minute, giving the baseline Early decelerations do not indicate the a spiky appearance on a CTG trace. A loss or reduction in variability to below five beats per presence of fetal distress. However, theseFigure 7-1: An early deceleration Figure 7-2: A late deceleration
  • 5. 144 MATERNAL CAREfetuses must be carefully monitored as they areat an increased risk of fetal distress. NOTE When early decelerations occur, normal variability of the fetal heart rate is reassuring that the fetus is not hypoxic.7-18 What are late decelerations?A late deceleration is a slowing of the fetalheart rate during a contraction, with the rateonly returning to the baseline 30 seconds ormore after the contraction has ended. With a late deceleration the fetal heart rate only returns to the baseline 30 seconds or more after the contraction has ended. NOTE When using a cardiotocograph, a late deceleration is diagnosed when the lowest point of the deceleration occurs 30 seconds or more after the peak of the contraction. Figure 7-3: Variable decelerations7-19 What is the significance NOTE Variable decelerations accompanied by lossof late decelerations? of variability may indicate fetal distress. Variable decelerations with good variability is reassuring.Late decelerations are a sign of fetal distressand are caused by fetal hypoxia. The degree towhich the heart rate slows is not important. It is 7-21 What is a baseline tachycardia?the timing of the deceleration that is important. A baseline fetal heart rate of more than 160 beats per minute. Late decelerations indicate fetal distress. 7-22 What are the causes of a baseline tachycardia?7-20 What are variable decelerations? 1. Maternal pyrexia.Variable decelerations have no fixed 2. Maternal exhaustion.relationship to uterine contractions. Therefore, 3. Salbutamol (Ventolin) administration.the pattern of decelerations changes from one 4. Chorioamnionitis (infection of thecontraction to another. Variable decelerations placenta and membranes).are usually caused by compression of the 5. Fetal haemorrhage or anaemia.umbilical cord and do not indicate thepresence of fetal distress. However, these 7-23 What is a baseline bradycardia?fetuses must be carefully monitored as they areat an increased risk of fetal distress. A baseline fetal heart rate of less than 100 beats per minute.Variable decelerations are not easy torecognise with a fetal stethoscope or doptone.They are best detected with a cardiotocograph.
  • 6. MONITORING THE CONDITION OF THE FETUS DURING THE FIRST STAGE OF LABOUR 1457-24 What is the cause of a 7-28 What fetal heart rate patternsbaseline bradycardia? indicate fetal distress during labour?A baseline bradycardia of less than 100 beats per 1. Late decelerations.minute usually indicates fetal distress which is 2. A baseline bradycardia.caused by severe fetal hypoxia. If decelerationsare also present, a baseline bradycardia indicates NOTE On cardiotocography, loss of variabilitythat the fetus is at great risk of dying. of beat-to-beat variation lasting more than 60 minutes also suggests fetal distress.7-25 How should you assess thecondition of the fetus on the basis 7-29 How should the fetal heart rateof the fetal heart rate pattern? pattern be observed during labour?1. The fetal condition is normal if a normal The fetal heart rate must be observed before, fetal heart rate pattern is present. during and after a contraction. The following2. The fetal condition is uncertain if the fetal questions must be answered and recorded on heart rate pattern indicates that there is an the partogram: increased risk of fetal distress. 1. What is the baseline fetal heart rate?3. The fetal condition is abnormal if the fetal 2. Are there any decelerations? heart rate pattern indicates fetal distress. 3. If decelerations are observed, what is their relation to the uterine contractions?7-26 What is a normal fetal heart 4. If the fetal heart rate pattern is abnormal,rate pattern during labour? how must the patient be managed?A normal baseline fetal heart rate without anydecelerations. 7-30 Which fetal heart rate pattern indicates that the fetal condition is good?7-27 Which fetal heart rate patterns 1. The baseline fetal heart rate is normal.indicate an increased risk of fetal 2. There are no decelerations.distress during labour?1. Early decelerations. 7-31 What must be done if2. Variable decelerations. decelerations are observed?3. A baseline tachycardia. First the relation of the decelerations to theThese fetal heart rate patterns do not indicate uterine contractions must be observed tofetal distress but warn that the patient must be determine the type of deceleration. Thenclosely observed as fetal distress may develop. manage the patient as follows: 1. If the decelerations are early or variable, NOTE If electronic monitoring is the fetal heart rate pattern warns that available, the fetal heart rate pattern there is an increased risk of fetal distress must be monitored electronically. and, therefore, the fetal heart rate must be checked every 15 minutes.Figure 7-4: Recording fetal observations on the partogram
  • 7. 146 MATERNAL CARE2. If late decelerations are present, the repeated if contractions start again, but management will be the same as that for not within 30 minutes of the first dose or fetal bradycardia. if the maternal pulse is 120 or more beats per minute.The observations of the fetal heart rate mustbe recorded on the partogram as shown in It is important that you know how to give fetalfigure 7-4. A note of the management decided resuscitation, as it is a lifesaving procedureupon must also be made under the heading when fetal distress is present, both during the‘Management’ at the bottom of the partogram. antepartum period and in labour. Always prepare to resuscitate the infant after7-32 What must be done if a fetal birth if fetal distress is diagnosed during labour.bradycardia is observed?Fetal distress due to severe hypoxia is present. NOTE Salbutamol (a beta2 stimulant) can also be given from an inhaler, but this method is lessTherefore, you should immediately do the effective than the parenteral administration.following: Give four puffs from a salbutamol inhaler. This1. Exclude other possible causes of can be repeated every ten minutes until the bradycardia by turning the patient onto uterine contractions are reduced in frequency and duration, or the maternal pulse reaches 120 her side to correct supine hypotension, and beats per minute. Uterine contractions can also stopping the oxytocin infusion to prevent be suppressed with nifedipine (Adalat). Nifedipine uterine overstimulation. 30 mg is given by mouth (1 capsule = 10 mg).2. If the fetal bradycardia persists, intra- The three capsules must be swallowed and not uterine resuscitation of the fetus must used sublingually. This method is slower than be continued and the fetus delivered as using intravenous salbutamol and the uterine quickly as possible. contractions will only be reduced after 20 minutes.7-33 How is intra-uterineresuscitation of the fetus given? THE LIQUOR1. Turn the patient onto her side.2. Give her 40% oxygen through a face mask. 7-34 Is the liquor commonly3. Start an intravenous infusion of Ringer’s meconium stained? lactate and give 250 μg (0.5 ml) salbutamol (Ventolin) slowly intravenously, after Yes, in 10–20% of patients, the liquor is ensuring that there is no contraindication yellow or green due to meconium staining. to its use. (Contraindications to The incidence of meconium-stained liquor is salbutamol are heart valve disease, increased in the group of patients that go into a shocked patient or patient with labour after 42 weeks gestation. tachycardia). The 0.5 ml salbutamol is diluted with 9.5 ml sterile water and given 7-35 Is it important to distinguish slowly intravenously over five minutes. between thick and thin, or yellow4. Deliver the infant by the quickest possible and green meconium? route. If the patient’s cervix is 9 cm or Although fetal and neonatal complications more dilated and the head is on the pelvic are more common with thick meconium, all floor, proceed with an assisted delivery cases of meconium-stained liquor should (forceps or vacuum). Otherwise, perform a be managed the same during the first stage Caesarean section. of labour. The presence of meconium is5. If the patient cannot be delivered important and the management does not immediately (i.e. there is another patient depend on the consistency of the meconium. in theatre) the dose of salbutamol can be
  • 8. MONITORING THE CONDITION OF THE FETUS DURING THE FIRST STAGE OF LABOUR 1477-36 What is the importance of 7-39 How and when are themeconium in the liquor? liquor findings recorded?1. Meconium-stained liquor usually indicates Three symbols are used to record the liquor the presence of fetal hypoxia or an episode findings on the partogram: of fetal hypoxia in the past. Therefore, fetal I = Intact membranes (i.e. no liquor draining). distress may be present. If not, the fetus is at high risk of distress. C = Clear liquor draining.2. There is a danger of meconium aspiration M = Meconium-stained liquor draining. at delivery. The findings are recorded in the appropriate space on the partogram as shown in figure 7-4. Meconium-stained liquor warns that either fetal distress is present or that there is a high risk of The liquor findings should be recorded when: fetal distress. 1. The membranes rupture. 2. A vaginal examination is done.7-37 How should you monitor the 3. A change in the liquor findings is noticed,fetus during the first stage of labour e.g. if the liquor becomes meconiumif the liquor is meconium stained? stained.1. Listen carefully for late decelerations. If present, then fetal distress must be CASE STUDY 1 diagnosed.2. If late decelerations are absent, then A primigravida with inadequate uterine observe the fetus carefully during labour contractions during labour is being treated for fetal distress, as about a third of fetuses with an oxytocin infusion. She now has with meconium-stained liquor will develop frequent contractions, each lasting more than fetal distress. 40 seconds. With the patient in the lateral3. If electronic monitoring is available, the position, listening to the fetal heart rate reveals fetal heart rate pattern must be monitored. late decelerations.7-38 How must the delivery be managed 1. What worries you mostif there is meconium in the liquor? about this patient?1. The infant’s mouth and pharynx must The late decelerations indicate that fetal be thoroughly suctioned after delivery distress is present. of the head, but before the shoulders and chest are delivered, i.e. before the 2. Should the fetus be infant breathes. This must be done delivered immediately? irrespective of whether a vaginal delivery or Caesarean section is done. No. Correctable causes of poor oxygenation of2. Anticipate that the infant may need to be the fetus must first be ruled out, e.g. postural resuscitated at delivery. If the infant has hypotension and overstimulation of the uterus asphyxia and needs intubation, suction the with oxytocin. The oxytocin infusion must airways via the endotracheal tube before be stopped and oxygen administered to the starting ventilation. patient. Then the fetal heart rate should be checked again.
  • 9. 148 MATERNAL CARE3. After stopping the oxytocin, the number of beats by which the fetal heart slowsuterine contractions are less frequent. during a deceleration is not important.No further decelerations of the fetalheart rate are observed. What further 4. Why should an abruptiomanagement does this patient need? placentae cause fetal distress?As overstimulation of the uterus with Part of the placenta has been separated fromoxytocin was the most likely cause of the the wall of the uterus by a retroplacental clot.late decelerations, labour may be allowed to As a result, the fetus has become hypoxic.continue. However, very careful observationof the fetal heart rate pattern is essential,especially if oxytocin is to be restarted. The CASE STUDY 3fetal heart should be listened to every 15minutes or fetal heart rate monitoring with a During the first stage of labour a patient’s liquorcardiotocograph should be started. is noticed to have become stained with thin green meconium. The fetal heart rate pattern is normal and labour is progressing well.CASE STUDY 2 1. What is the importance of theA patient who is 38 weeks pregnant presents change in the colour of the liquor?with an antepartum haemorrhage in labour.On examination, her temperature is 36.8 °C, Meconium in the liquor indicates an episodeher pulse rate 116 beats per minute, her of fetal hypoxia and suggests that there may beblood pressure 120/80 mm Hg, and there is fetal distress or that the fetus is at high risk oftenderness over the uterus. The baseline fetal fetal distress.heart rate is 166 beats per minute. The fetalheart rate drops to 130 beats per minute during 2. Can thin meconium be acontractions and then returns to the baseline sign of fetal distress?35 seconds after the contraction has ended. Yes. All meconium in the liquor indicates either fetal distress or that the fetus is at high risk of1. Which of the maternal observations fetal distress. The management does not dependare abnormal and what is the probable on whether the meconium is thick or thin.cause of these abnormal findings?A maternal tachycardia is present and there is 3. How would you decide whetheruterine tenderness. These findings suggest an this fetus is distressed?abruptio placentae. By listening to the fetal heart rate. Late decelerations or a baseline bradycardia will2. Which fetal observations are abnormal? indicate fetal distress.Both the baseline tachycardia and the latedecelerations. 4. How should the fetus be monitored during the remainder of the labour?3. How can you be certain that The fetal heart rate pattern must bethese are late decelerations? determined carefully every 15 minutes in orderBecause the deceleration continues for more to diagnose fetal distress should this occur.than 30 seconds after the end of the contraction.This observation indicates fetal distress. The
  • 10. MONITORING THE CONDITION OF THE FETUS DURING THE FIRST STAGE OF LABOUR 1495. What preparations should bemade for the infant at delivery?The infant’s mouth and pharynx must be wellsuctioned immediately after the head hasbeen delivered. If the infant does not breathewell directly after delivery, intubation andfurther suctioning of the larger airways may berequired before ventilation is started.