Primary maternal care preterm labour and preterm rupture of the membranes
5 Preterm labour and preterm rupture of the membranesBefore you begin this unit, please take the PRETERM LABOUR ANDcorresponding test at the end of the book toassess your knowledge of the subject matter. You PRETERM RUPTURE OFshould redo the test after you’ve worked through THE MEMBRANESthe unit, to evaluate what you have learned. Objectives 5-1 What is preterm labour? Preterm labour is diagnosed when there are When you have completed this unit you regular uterine contractions before 37 weeks of should be able to: pregnancy, together with either of the following: • Define preterm labour and preterm 1. Cervical effacement and/or dilatation. rupture of the membranes. 2. Rupture of the membranes. • Understand why these conditions are very important. 5-2 What is preterm rupture • Understand the role of infection in of the membranes? causing preterm labour and preterm Preterm rupture of the membranes is rupture of the membranes. diagnosed when the membranes rupture before • List which patients are at increased risk 37 weeks, in the absence of uterine contractions. of these conditions and what preventive measures should be taken. 5-3 What is prelabour rupture of the membranes? • Diagnose preterm labour and preterm rupture of the membranes. Prelabour rupture of the membranes is defined • Initiate the correct management and as rupture of the membranes for at least one hour before the onset of labour in a term pregnancy. appropriate referral of patients.
PRETERM LABOUR AND PRETERM RUPTURE OF THE MEMBRANES 975-4 How should you diagnose preterm membranes and placenta. Later these bacterialabour if the gestational age is unknown? may colonise the liquor, from where they may infect the fetus.Preterm labour is diagnosed if the estimatedfetal weight is below 2500 g. The symphysis- Infection of the membranes and placentafundus height will be less than 35 cm. (chorioamnionitis) may occur with either intact or ruptured membranes.5-5 Why are preterm labour and pretermrupture of the membranes important? 5-8 What is the clinical presentationPreterm labour and preterm rupture of the of chorioamnionitis?membranes are major causes of perinataldeath because: Usually chorioamnionitis is asymptomatic (subclinical chorioamnionitis) and, therefore,1. Preterm delivery, especially before 34 weeks, the clinical diagnosis is often not made. commonly results in the birth of an infant However, the following signs may be present: who develops hyaline membrane disease and other complications of prematurity. 1. Fetal tachycardia.2. Preterm labour and preterm rupture of 2. Maternal pyrexia and/or tachycardia. the membranes are often accompanied by 3. Tenderness of the uterus. bacterial infection of the membranes and 4. Drainage of offensive liquor, if the placenta, that may cause complications for membranes have ruptured. both the mother and the fetus. The mother If any of the above signs are present, a diagnosis and fetus may develop severe infection, of clinical chorioamnionitis must be made. which is life threatening. 5-9 What factors may predispose5-6 What is the commonest known to chorioamnionitis?cause of preterm labour and pretermrupture of the membranes? 1. Rupture of the membranes. 2. Exposure of the membranes due toIn many cases the cause is unknown, but dilatation of the cervix.increasing evidence points to infection of the 3. Coitus during the second half ofmembranes and placenta as the commonest pregnancy.known cause of both preterm labour andpreterm rupture of the membranes. However, in many cases, the factors that result in chorioamnionitis are not known. Infection of the membranes and placenta is the commonest recognised cause of preterm labour 5-10 Can chorioamnionitis cause and preterm rupture of the membranes. complications during the puerperium? Yes, it can cause serious problems.5-7 What is infection of the 1. Bacteria that have colonised the amnioticmembranes and placenta? fluid, may infect the fetus and the infantInfection of the membranes and placenta may present with signs of infectioncauses an acute inflammation of the placenta, (congenital pneumonia or septicaemia) atmembranes and decidua. This condition is or soon after birth.called chorioamnionitis. It may occur with 2. Chorioamnionitis may cause infection ofintact or ruptured membranes. the genital tract (puerperal sepsis) which, if not treated correctly, may result inBacteria from the cervix and vagina spread septicaemia, the need for hysterectomy,through the endocervical canal to infect the and possibly in maternal death. These
98 PRIMAR Y MATERNAL CARE complications can usually be prevented 7. Have any of the maternal, fetal or placental by starting a course of broad-spectrum factors listed above. antibiotics (e.g. intravenous ampicillin plus metronidazole), as soon as the diagnosis of The most important risk factor for preterm clinical chorioamnionitis is made. labour is a previous history of preterm delivery.5-11 What factors other than 5-13 What can be done to decrease thechorioamnionitis can lead to incidence of these complications?preterm labour and pretermrupture of the membranes? 1. Take measures to ensure that all pregnant women receive antenatal care.The following maternal, fetal and placental 2. Identify patients with a past history offactors may be associated with preterm labour preterm labour.and/or preterm rupture of the membranes: 3. Give advice about the dangers of smoking,1. Maternal factors: alcohol and the use of habit-forming drugs. • Pyrexia, as the result of an acute 4. Advise against coitus during the late 2nd infection other than chorioamnionitis, and in the 3rd trimester in pregnancies at e.g. acute pyelonephritis or malaria. high risk for preterm labour or preterm • Uterine abnormalities, such as rupture of the membranes. If coitus occurs congenital uterine malformations during pregnancy in these patients, the use (e.g. septate or bicornuate uterus) and of condoms must be recommended as this uterine myomas (fibroids). may reduce the risk of chorioamnionitis. • Incompetence of the internal cervical 5. Insert a McDonald suture at 14–16 weeks, os (‘cervical incompetence’). in patients with a proven incompetent2. Fetal factors: internal cervical os. • A multiple pregnancy. 6. Prevent teenage pregnancies. • Polyhydramnios 7. Improve the socio-economic and • Congenital malformations of the fetus. nutritional status of poor communities. • Syphilis. 8. Arrange that the workload of women,3. Placental factors: who have to do heavy manual labour, is • Placenta praevia. decreased when they are pregnant and • Abruptio placentae. that an opportunity to rest during working hours is allowed.5-12 Which patients are at an increasedrisk of preterm labour or preterm 5-14 How should you manage a patientrupture of the membranes? at increased risk of preterm labour or preterm rupture of the membranes?Both preterm labour and preterm rupture ofmembranes are more common in patients who: 1. Patients at increased risk must have 2 weekly vaginal examinations from 241. Have a past history of preterm labour. weeks, in order to make an early diagnosis2. Have no antenatal care. of preterm cervical effacement and/or3. Live in poor socio-economic dilatation. circumstances. 2. In all women with cervical effacement or4. Smoke, use alcohol or abuse habit-forming dilatation before 34 weeks, the following drugs. preventive measures can then be taken:5. Are underweight due to undernutrition. • Bed rest. This can be at home, except6. Have coitus in the 2nd half of pregnancy, when the home circumstances are poor, when they are at an increased risk of preterm labour or infections.
PRETERM LABOUR AND PRETERM RUPTURE OF THE MEMBRANES 99 in which case the patient should be DIAGNOSIS OF referred to the hospital for admission. • Sick leave must be arranged for PRETERM LABOUR AND working patients. PRETERM RUPTURE OF • Coitus must be forbidden. • Advice must be given to report THE MEMBRANES immediately, if contractions or rupture of the membranes occur. • Women with preterm labour or preterm 5-16 How should you distinguish rupture of the membranes must be seen between Braxton Hicks contractions and as soon as possible, and the correct the contractions of preterm labour? measures taken to prevent the delivery Braxton Hicks contractions: of a severely preterm infant. 1. Are irregular. All patients should be told to immediately 2. May cause discomfort but are not painful. report preterm labour or preterm rupture of the 3. Do not increase in duration or frequency. 4. Do not cause cervical effacement or membranes. dilatation. The duration of contractions cannot be used5-15 What should you do if a patient as Braxton Hicks contractions may last up tothreatens to deliver a preterm infant? 60 seconds.1. Infants born between 34 and 36 weeks can In contrast, the contractions of preterm or usually be cared for in a level 1 hospital. early labour:2. However, women who threaten to deliver between 28 and 33 weeks, should be 1. Are regular, at least one per 10 minutes. referred to a level 2 or 3 hospital with a 2. Are painful. neonatal intensive care unit. 3. Increase in frequency and duration.3. If the birth of a preterm baby cannot be 4. Cause effacement and dilatation of the prevented, it must be remembered that the cervix. best incubator for transporting an infant is the mother’s uterus. Even if the delivery 5-17 How should you confirm the is inevitable, an attempt to suppress labour diagnosis of preterm labour? should be made, so that the patient can be Both of the following will be present in a transferred before the infant is born. patient of less than 37 weeks gestation:4. The better the condition of the infant on arrival at the neonatal intensive care unit, 1. Regular uterine contractions, palpable on the better is the prognosis. abdominal examination, of at least one per 10 minutes. 2. A history of rupture of the membranes, or cervical effacement and/or dilatation on vaginal examination. 5-18 How can you diagnose preterm rupture of the membranes? 1. A patient of less than 37 weeks gestation will give a history of sudden drainage of liquor followed by a continual leak
100 PRIMAR Y MATERNAL CARE of smaller amounts, without associated indicating that the membranes have uterine contractions. ruptured. If blue litmus is used, it will2. A sterile speculum examination will remain blue with rupture of membranes or confirm the diagnosis of ruptured change to red if the membranes are intact. membranes.3. A digital vaginal examination must not be 5-21 How should you manage done as it is of little value in diagnosing patients with preterm labour, rupture of the membranes and may preterm rupture of membranes and increase the risk of infection. prelabour rupture of membranes? A digital vaginal examination must not be done 1. If the gestational age is less than 36 weeks, in preterm rupture of the membranes. these patients should be referred to a level I hospital for admission. If the gestational age is less than 34 weeks, she must be5-19 What is the value of a sterile referred to a level 2 hospital.speculum examination when preterm 2. If the gestational age is 36 weeks of more,rupture of the membranes is suspected? patients can safely be delivered in a midwife obstetric unit (MOU) or district hospital.1. The danger of ascending infection is not At a gestational age of 36 weeks babies will increased by this procedure. not develop the complications of preterm2. Observing drainage of liquor from the infants and could be discharged 6 hours cervical os confirms the diagnosis of following delivery with their mothers. ruptured membranes.3. If no drainage of liquor is observed, drainage can sometimes be seen if the 5-22 How will you decide that a patient patient is asked to cough. is less than 36 weeks pregnant if the4. If no drainage of liquor is seen, a smear duration of the pregnancy is unknown? should be taken from the posterior This is done by measuring the symphysis- vaginal fornix with a wooden spatula to fundus height and by doing a complete determine the pH. abdominal examination. An estimated fetal5. The possibility of cord prolapse can be weight of less than 2500 g, suggests a gestational excluded or confirmed. age of less than 36 weeks. The symphysis-fundus6. It is also important to see whether the height measurement will be less than 34 cm. cervix is long and closed, or whether there is already clear evidence of cervical 5-23 What should be done if preterm effacement and/or dilatation. labour has been diagnosed and the7. A patient with a profuse vaginal discharge patient is less than 34 weeks pregnant? or stress incontinence (leaking urine when coughing or laughing) may think Contractions should be suppressed with that she is draining liquor. A speculum nifedipine (Adalat). The patient must then examination will help to confirm or rule be transferred as an urgent transferal to a out this possibility. level 2 hospital. If nifedipine is not available salbutamol (Ventolin) can be used. This5-20 How should you test the vaginal pH? measure will:1. The pH of the vagina is acid but the pH of 1. Improve the chance of successful liquor is alkaline. suppression of preterm labour at the2. Red litmus paper is pressed against the hospital. moist spatula. If the red litmus changes to 2. Reduce the risk of a delivery before arrival blue, then liquor is present in the vagina, at the hospital or clinic.
PRETERM LABOUR AND PRETERM RUPTURE OF THE MEMBRANES 101Infants born before 34 weeks are at increased 5-28 What are the contraindications to therisk of developing complications. Therefore, use of salmotamol in suppressing labour?suppression of contractions to allow 1. Heart valve disease. The use of salmutamolcontinuation of pregnancy is important in (or another beta2 stimulant), can endangerthese cases. The earlier the suppression of the patient’s life, especially if she has acontractions is started the better the chance of narrowed heart valve, e.g. mitral stenosis.successful suppression will be. 2. A shocked patient. 3. A patient with a tachycardia, e.g. as the5-24 How would you decide that a patient result of an acute infection.is less than 34 weeks pregnant if theduration of the pregnancy is uknown? 5-29 What advice should youThis is done by measuring the symphysis- give to a woman who hasfundus height and by doing a complete delivered a preterm infant?abdominal examination. 1. She should be seen at a level 2 hospitalLabour must be suppressed if the estimated before her next pregnancy to be assessed forfetal weight is less than 2000 g as this suggests possible causes, e.g. cervical incompetence.an estimated gestational age of less than 2. She must book early in any future34 weeks. The symphysis-fundus height pregnancy.measurement will be less than 33 cm.5-25 How should you give nifedipine for CASE STUDY 1the suppression of preterm labour?Three nifedipine (Adalat) 10 mg capsules (total A patient, 32 weeks pregnant, presents with30 mg) should be taken by mouth. If there regular painful uterine contractions. Sheare still contractions with cervical dilatation is apyrexial and appears clinically well. Onand effacement 3 hours after the initial dose, a vaginal examination, the cervix is 4 cm dilated.follow-up dose of 20 mg must be given. The fetal heart rate is 138 beats per minute with no decelerations.5-26 What are the contraindications to theuse of nifedipine in suppressing labour? 1. Is the patient in true or false labour? Give the reasons for your diagnosis.Nifedipine (Adalat) cannot be used for thesuppression of preterm labour if patients have She is in true labour because she is gettinghypertension, e.g. suffering from any of the regular painful contractions and her cervix ishypertensive disorders of pregnancy. 4 cm dilated.5-27 How should you use salmutamol 2. What signs exclude a diagnosisfor the suppression of preterm labour? of clinical chorioamnionitis?1. A half an ampoule (0.5 ml = 250 μg) of The patient is apyrexial, clinically well and has salbutamol (Ventolin) is diluted with 9.5 ml a normal fetal heart rate. of sterile water in a 10 ml syringe and administered slowly intravenously (0.5 ml 3. Why could chorioamnionitis still be per minute) while the maternal heart rate is the cause of her preterm labour? carefully monitored for a tachycardia. Because chorioamnionitis is often2. The patient must be warned that salbutamol asymptomatic (subclinical chorio-amnionitis). causes tachycardia (palpitations).
102 PRIMAR Y MATERNAL CARE4. Would you allow labour to continue 4. Is this patient at high risk of havingor would you suppress labour prior to or developing chorioamnionitis?referring the patient to the hospital? Yes. The preterm prelabour rupture ofLabour should be suppressed because the the membranes may have been caused bypregnancy is of less than 34 weeks duration. chorioamnionitis. In addition, all patients with ruptured membranes are at an increased risk5. How should labour be suppressed? of developing chorioamnionitis.Labour must be suppressed using nifedipine 5. Should the patient be referred to(Adalat) or salbutamol (Ventolin). a level I (district hospital/MOU) or level II hospital? Give your reasons.CASE STUDY 2 She is 36 weeks pregnant and there are no signs of chorio-amnionitis. She should beA patient, who is 36 weeks pregnant, reports referred to a level I hospital or MOU.that she has been draining liquor since earlierthat day. The patient appears well, with normalobservations, no uterine contractions and the CASE STUDY 3fetal heart rate is normal. An unbooked patient presents at a primary1. Would you diagnose rupture care clinic with a 5 day history of rupturedof the membranes on the history membranes. She is pyrexial with lowergiven by the patient? abdominal tenderness and is draining offensive liquor. She is uncertain of her datesNo, other causes of fluid draining from the but abdominal examination suggests that shevagina may cause confusion, e.g. a vaginitis or is at term. Treatment has been started withstress incontinence. oral ampicillin.2. How would you confirm 1. What signs of clinical chorioamnionitisrupture of the membranes? does the patient have?A sterile speculum examination should be She is pyrexial, with lower abdominaldone. If there is no clear evidence of liquor tenderness and she has offensive liquor.draining, the vaginal pH must be determinedwith Litmus paper to identify liquor. 2. How should the patient be managed?3. Why should you not perform a digital There is danger of spreading infection invaginal examination to assess whether both the mother and fetus if the infant is notthe cervix is dilated or effaced? delivered. The patient must be referred to the next level of care as an urgent case.A digital vaginal examination is contra-indicated in the presence of rupture of the 3. Is oral ampicillin the correct initialmembranes if the patient is not already in treatment while waiting for thelabour, because of the risk of introducing transfer? Give your reasons.infection. Chorioamnionitis may result in a severe infection of the genital tract that may cause a maternal death. These complications can usually be prevented by starting broad- spectrum antibiotics (ampicillin and
PRETERM LABOUR AND PRETERM RUPTURE OF THE MEMBRANES 103metronidazole) as early as possible. Theampicillin must be given intravenously.4. Why is the infant at increased riskfor neonatal complications?The chorioamnionitis has already spread to theliquor as this is offensive. Therefore, the fetusmay also be infected and may present withcongenital pneumonia or septicaemia at birth.