Labour. Prof. Mustafa Gawass FRCOG , FRCPI. objectives. Define labour . Understand the components of labour (passage, passenger, power). Be able to take a focused history, examination and anlyse the symptoms and signs to diagnose labour . Describe the stage sand phases of labour .
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Labour Prof. Mustafa GawassFRCOG, FRCPI
objectives • Define labour. • Understand the components of labour (passage, passenger, power). • Be able to take a focused history, examination and anlyse the symptoms and signs to diagnose labour. • Describe the stage sand phases of labour. • Discuss the mechanism of labour. • Discuss the management of labour.
Labour (parturition) • It Is the process where by with time regular uterine contractions, brings about progressive affacment and dilatation of the cervix, resulting in delivery of the fetus from the uterus and expulsion of the placenta at or beyond 24 (or 28) completed weeks of pregnancy. It is a social, psycological and economical event for the couple, family and community.
Cervical dilatation: The cervix begins dilating and stretching beyond the normal dimensions and is measured in centimeters. (0-10cm). • Cervical effacement: softening, thinning and shortening of the cervix. It is expressed in percentage (0 – 100%)
A 20 year old primigravida comes to maternity unit at 39 weeks gestation complaining of regular uterine contractions, 3-4/10min. For the past 6 hours. The contractions are becoming more frequent lasting 45-50 sec. she denies any vaginal fluid leakage. The blood pressure, pulse and temperature are normal. • Vaginal examination cephalic, head at s-1,90% affaced, 5 cm dilated, soft and anterior. FH=133bpm . • What is your diagnoses?
Term Labour PTL prolonged 24 W 42W 40W 28 W 37 W 1 LNMP Labour can occur at:
Normal labour: • Spontaneous expulsion, through the natural passages (birth canal) of a single, mature (37-42 completed weeks of pregnancy) Alive fetus, presenting by vertex, within a reasonable time, without fetal or maternal complications.
passengers • The following will pass during labour (fetus, cord, placenta and membranes). The most important to pass is the head and shoulder
Moulding of the skull: • means obliteration of the suture line between the bones and overlapping of the un-united bones of the fetal skull, and is measured by degree. As the degree of moulding increase- means there is CPD
Fetal attitude: is the relation of the fetal parts to each other • 1- flexion attitude (common) • 2- extension attitude (rare).
Clinical course of labour Onset of labour:not definitely known – however there are several theories, but none of them is completely proven. Mechanical theories: - uterine distension Hormonal theories: • Maternal : • progesterone withdrawal • oxytocin stimulation • prostaglandins • serotonin • fetal: • fetal cortisol • fetal membranes • Neuronal factors: • sympathetic- alpha receptor stimulation
Diagnosis • symptoms: • True labour pains – colicky pain in the abdomen and back are characterized by:
Show – blood stained mucous. • SROM • Signs: • palpable or recorded uterine contraction • effacement and dilation of the cervix • formation of forewater
THE ACTIVE STAGE OF LABOUR – WHEN THE CERVIX IS MORE THAN 3 CM DILATED AND FULLY EFFACED STAGES OF LABOUR: I-The First stage: stage of cervicaleffacement and dilatation Definition:the first stage of labour refers to the period from the onset of true uterine contractions to the fully dilation of the cervix, when the diameter of the cervical os measures 10cm.
Duration: • primigravida = 8-12 h • multigravida = 6-8 h Phases of the first stage: • Latent phase: started when the cervix dilatated slowly and reached to about 3cm. • in primigravida = 8h • in multigravida = 4h • - Active phase: rapid dilatation of the cervix to reach 10cm • in primigravda = 4h • in multigravida =2h
The active phase is divided into: • Accelerative phase • Slopping phase • Decelerative: • prolonged active phase • primary dysfunction: dilation in active phase of<1cm/hr • secondary arrest: active phase dilation stops or slow significantly. N.B – in primigravida the cervix dilates from above downwards, in multigravida dilatation of the internal os, taking up of the cervix and dilatation of the external os occurs simultaneously.
Factors affecting cervical dilatation: • Contraction and retraction of the uterus. • The bag of fore-water. • Absence of membranes. • Fitting of the presenting part to the lower segment and the cervix. • Pre-labour changes in the cervix (eg, softening)
II-The Second stage of labour: stage of delivery of the fetus. Definition:the second stage of labour refers to the period from complete cervical dilatation to the birth of the fetus.29-30 Duration: • in primigravida =1 h • in multigravida = ½ h however the timing of the second stage is very different to determine and controversial and can be extended as much as there is progress in descent and no harm to the mother or fetus
The second stage of labour had two phases: • Passive phase – stage of descent of the presenting part and dilatation of the vagina – due to contraction and retraction of the uterine muscle. • Expulsive phase – stage of bearing down – due to contraction and retraction of the uterine muscle and voluntary efforts by diaphragm and abdominal muscles.
Mechanism of labour in vertex presentation: • Definition: The spontaneous adjustments of the fetal position and attitude to affect efficient passage of the fetus through the pelvis, marked by progressive descent until delivery of the fetus. • Delivery of the fetal head: • A- Descent: is a continuous movement throughout the process of delivery, however it becomes more rapid in the second stage of labour, it is caused by: • -Uterine contraction and retraction. • -bearing down effort – mainly in the second stage of labour
In normal pelvis, the fetal head enters with the sagittal suture in the transverse diameter (or occasionally oblique diameter of the brim). If the sagittal suture in between the symphysis pubis and sacral promontory – both parietal bones are felt vaginally at the same level – the head is said to be (synclitic). In such case the biparietal diameter (9.5cm) is the diameter of engagement. However some degree of lateral inclination of the head over the shoulder – (Asynclitism) is present normally as the head enters the pelvic inlet.
*If the sagittal suture lies close to the sacrum and the anterior patietal bone lies over the inlet (Anterior parietal bone presentation) - Anterior asynclitism. *If the sagittal suture lies close to the symphysis pubis and the posterior parietal bone lies over the inlet (posterior parietal bone presentation) – posterior asynclitism.
Causes of non-engagement: • Erroneous dates (primigravida) • Extra-uterine: • full bladder or loaded rectum • Pelvic tumours • Pendulous abdomen and marked lumbar lordosis. • High angle of inclination of the pelvis. • Contracted pelvis. • -Uterine: • Poor uterine tone. • Congenital deformities. • Fibromyomata. • Placenta previa.
-Fetal: • polyhydramnios. • Short umbilical cord(acutal or relative, due to entanglement) • Large baby. • Deflexion attitude, and malposition. • Multiple pregnancy. • Hydrocephalus. Engagement – can be assessed by abdominal station in fifths during antenatal period, and by abdominal and vaginal stations during labour.
Increased flexion:as the head descends, it meets resistance from the pelvic walls and floor and this leads to increased flexion of the head. As the head flexed it brings the shortest longitudinal diameter of the head (sub-occipito-bregmatic – 9.5cm) to pass through the birth canal. Flexion is explained by the (two armed lever theory).
D-Internal rotation: the internal rotation occurs as the head descends through the pelvic cavity. As the head enters the pelvic inlet in transverse diameter will rotate 3/8 of the cycle to pass through the pelvic outlet in antero-posterior diameter. The rotation is favoured by the slopping shape of the pelvic floor, angling the leading point of the head (occiput) in downward and forward direction, by the effect of the contraction and retraction of the uterus.
E-Crowning, extension and delivery of the fetal head: The combined effect of descent and internal rotation bring the presenting diameter to the plane of the pelvic outlet, with the occiput lying under the pubic arch and the sinciput at the lower border of the sacrum or coccyx. When the widest diameter of the fetal head is embraced by the distended vulva, it is said to be crowned. The occiput remains under the pubic arch but the sinciput sweeps forwards as the neck extends.
The head is acted upon by: • The downward and forward force of the uterine contraction and retraction. • The upward and forward force offered by pelvic floor resistance so the head passes forwards i.e. extends vertex, forehead, and face come out successively. Frequently, especially in primigravida, the soft tissues are not able to distend equally so that tearing of the perineum and adjacent tissues may occur unless steps are taken to avoid it by making a formal incision (episiotomy).
F-Restitution and external rotation: Following delivery of the head the occiput rotates to the lateral position, in the opposite direction of internal rotation to correct the twist of the head on the shoulders produced by internal rotation. The internal rotation of the shoulders inside the pelvis transmitted to the delivered head which in turn move one eight of a circle outside the pelvis, in the same direction as that of the restitution, so at the end the occiput is towards one thigh and the face is towards the other thigh.
Delivery of the shoulder and body: The widest diameter of the shoulders,( the bi-acromial diameter), pass the pelvic brim at the time when the anterior rotation of the head is occurring. Thus the anterior rotation of the occiput is favourable for both the head and the shoulders. Similarly external rotation of the head is associated with rotation of the shoulders to bring them into the antero-posterior diameter of the outlet. With further descent, the anterior shoulder delivered first from under the pubic arch, followed by posterior shoulder, during which time lateral flexion of the trunk is occurring. The trunk and buttocks follow with the same or the next contraction.
Even in the course of normal delivery, there are many variations of the mechanisms, dependent on the variation in the size and shape of the pelvis and of the fetal head. III-The Third stage of labour:the stage of expulsion of the placenta and membranes.
Duration: up to 30 minutes, however the average length of the third stage of labour is 10 minutes. • Mechanism: the third stage is made of two phases: • The first phase: phase of placental separation occurs through the spongiosa layer of the decidua at the time of expulsion of the baby or very soon afterwards. The shearing force responsible for the separation is the contraction and retraction of the uterus, reducing the uterine volume and the area of the placental site, as the fetus is expelled.
The second phase: phase of placental expulsion – The separated placenta descends from the upper (active) segment into lower (passive) uterine segment, cervix, and vagina by two mechanisms: • -Schultze mechanism:(80%) • The placenta delivered as an inverted umbrella with it’s fetal surface presenting first followed by the membranes with retro-placental haematoma. • Mattews – Duncan mechanism: (20%) • The placenta delivered side way and it presents with it’s inferior surface first.
Management of labour The management of labour should be commenced during the antenatal period, and the women should be classified as high or low risk pregnancy. The medical or surgical problems should be corrected as in case of (anaemia, hypertension, urinary tract infection), vaccination should be given if necessary, and all investigations should be performed and prepared such as (HIV, HCV, Hbs Ag, blood grouping…….etc).
Also the patient should be advised to attend the antenatal class (parenterful class) and visit the hospital including the labour ward to be familiar to the place and staff. Once labour is commenced and the patient arrived to the admission room the following to be done:
-Taking history or reviewing the antenatal file. • 1-Last menstrual period – expected date of confinement. • 2-Time of onset of labour. • 3-Frequency and duration of contraction (3-4cm/10min). • 4-Presence or absence of amniotic fluid leakage. • 5-Presence or absence of show or vaginal bleeding. • 6-Past obstetric history especially mode of previous delivery, presentation, mode of delivery, and weight of previous children. • 7-Past medical or surgical history that may affect labour or delivery, especially diabetes, heart disease, respiratory disease allergies, and any medication.
B-Examination: • .General: • a-pallor, oedema, varicosities, height, and built. • b-Vital signs (BP, P, T) • c-Examination of heart, lungs, breast and other organs if necessary • .Abdominal Examination: • a-To determine fundal height in cm using tape measure (to determine gestational age clinically), fetal lie, presentation, engagement in fifths, size of the fetus, amount of liquor, fetal heart rate. • b-The frequency and duration of the contraction.
.Vaginal Examination: to assess the following. • a-Cervical dilatation in cm and effacement in %. • b-Length of the cervix. • c-Consistency of the cervix • d-Position of the cervix • e-State of the membranes, amount and colour of liquor. • f-fetal presentation, position and station. • g-pelvic architecture.
DO NOT DO VAGINAL EXAMINATION IN CASES OF VAGINAL BLEEDING BEFORE THE PLACENTA PREVIA IS EXCLUDED. DO STERIL SPECULUM EXAMINATION IF SUSPECTED PLROM, IF THE WOMAN IS NOT IN LABOUR. If the woman diagnosed as having active labour – to be admitted to labour ward. N.B- active labour means –regular strong and frequent uterine contraction 3-4/10min lasting 45-50 sec, and the cervix is fully effaced and 2.5-3cm dilated.
Arrival to the labour ward: I-first stage of labour: 1-Ensure patient’s privacy by covering her with sheaths or blankets. 2-Reassure and show great sympathy and interest. 3-Record maternal vital signs every hour (BP, P, T). 4-Take blood for grouping and cross match for high risk patients. 5-Monitor: a-high risk patients should have a continuous electronic fetal heart monitoring.
b-low risk patients should have brief electronic fetal heart monitoring if NORMAL, to be followed by intermittent auscultation: -first stage every 15min -second stage every 5min 6-Limit oral intake to small amount of clear fluid or frozen pineapple. 7-Give all patients in active labour Ranitidine (Zentac) 150mg orally / 6hourly. 8-Nurse the patient in: a-left lateral position for mediated patients. b-sitting or semi-reclining for unmediated patients.
9-Encourage spontaneous voiding, catheterization may be necessary. 10-Test all urine specimen for proteins, sugar, and acetone. 11-Give IV fluids during labour to avoid dehydration a-0.9% Nacl or hartmann’s solution at 80-125ml/hr b-Supplementation with 5% dextrose to prevent ketosis and hypoglycemia. 12-Give analgesia/anesthesia as required. a-Pethidine (50-150mg)IM. b-Diamorphin (5-10mg)IM. Every 3-4 hours. *avoid giving it too early in labour < 3-4cm cervical dilation or too late when the delivery is expected within 1-2hours.
*if given too late: -inform the pediatrician -give Naloxon (Narcon) 0.02mg IM to the neonate. c-Use Entonox (NO2 50%+O2 50%) by mask if available. d-Use epidural analgesia in selected cases if available such as Breech, Twins, preterm delivery. e-Give anti-emetics such as Metoclopromide (5-10mg)IM if necessary, but should not be routine. 13-Do vaginal examination to: a-assess progress of labour every 2-4hr b-or immediately after rupture of membranes c-FHR abnormalities.
14-Recall all the observations in labour in Partogram. 15-Consider augmentation with syntocinon if progress of labour is slow (partogram). -1000 ml Hartmann’s solution or normal saline + 10 units syntocinon (pitocin) -Begin the infusion using a pump at 4 milliunits per minute and double the dose every 20 minutes to a maximum of 32 milliunits/min. -Or begin with 15 drops / min and increase the rate by 10 drops every 30 minutes untill adequate contractions.
II-second stage of labour: • Once the patient reach the second stage of labour and have the desire to push down then: • 1-Put the patient in lithotomy position or other positions clean the vulva, and perineum with antiseptic solution. • 2-Encourage organized pushing down which she is feeling to do so • -Monitor the uterine contraction and fetal heart more frequent. • -Use syntocinon if progress is slow and no contractions. • -When the head appears at the vulva, the perineum is supported during uterine contraction by sterile pad to promote flexion and prevent premature extension of the head by pressing up on the sinciput until crowning occur.
-After crowning the head is allowed to be delivered by extension slowly in between the contractions by sliding the perineum over the face. • -DO episiotomy if necessary under local anaesthetic ( 10-20 ml) of 1% lignocain, but should not be routine. • -Wait for the next contraction to deliver the shoulder and trunks. • -Clamp and deliver the cord and baby to be handled to pediatrician.
III-Third stage of labour: The management of third stage is aimed at: 1-Complete delivery of the after birth (placenta and membranes). 2-Prevention of acute inversion of the uterus. 3-prevention of postpartum haemorrhage