Labour Flashcards
1
Q
Parturition
A
- Progessive increase in intensity and frequency of uterine contractions leading to dilatation of the cervix, descent of the fetus, and ultimately explusion of the baby, placenta and membranes.
- Consists of progessive cervical effacement dilation from uterine contractions occuring at least every 5mins and lasting 30-60seconds.
2
Q
Pelvic Shapes
A
- The female pelvis can be classified into different shapes. This is clinically relavent since each shape has a different point of largest diameter. it will effect how the fetal head will engage.
- Gynecoid - this is the classic female pelvis found in ~50% of women. It is characterized by a cylindrical shape that is spacious throughout. Fetal head will generally rotate into the occipitoanterior position.
- Android - this is the classic male pelvis, found in <30% of women. Characterized by a triangular inlet. In this type, there is limited space at the inlet with pregressively less space as you move down. Fetal head goes into occipitoposterior position. Arrest of descent is common at midpelvis.
- Anthropoid - Found in ~20% of women. Characterized by an oval inlet (longest along the vertical). Fetal head engages in the occipitoposterior position, because there is more room in the posterior pelvis.
- Platypelloid - Found in <3% of women. Characterized by an oval shaped inlet (longest along the horizontal). Fetal head engages in the transverse diameter.
3
Q
Engagement
A
- When widest diameter of fetus has passed through the pelvic inlet.
4
Q
What physiologic preparatory events occur before labour?
A
- Lightening - A flattening of the upper abdomen and increase in size of lower abdomen as the fetal head moves into the brim of the pelvis. This occurs 2 or more weeks before labour in primigravid women and occurs in early labour in multigravida women.
- False labour - in the last 4-8 weeks of pregnancy the uterys has irregular, painless, contractions. They can be rhythmic and of mild intensity. In the last month these contractions may occur more frequently and with greater intensity (Braxton Hicks Contractions). This is considered false labour because there is no cervical dilation or effacement.
- Cervical effacement - before labour the cervic softens due to increase water content and collagen lysis. Cervix shortens as it is progressively taken up into the lower segment of the uterus. With effacement the mucous plug within the cervix may be released (bloody show).
5
Q
Stage 1 of labour
A
- Stage 1 (0-10cm dilatation) consists of 2 phases
- Latent phase (dilatation to 3-4cm) - cervical effacement and rapid cervical dilation. Contractions needs to get at least 25mmHg to start dilating cervix.
- Active phase - Starts when cervix is 4cm dilated in presence of regulary occuring uterine contractions. It is characterized by more rapid cerival dilation.
- Length of first stage may be prolonged if this is the first child, mother is older, mother has high BMI, or patient used an epidural.
- Lasts ~12-13hrs for first child and ~7-8hrs for second child
6
Q
“Good contractions”
A
- In the 1st stage contractions needs to become coordinated, regular, more intense, and more frequent.
- Good contractions in active phase= every 2-3mins, lasting 45-60seconds, having intensity of 60-70mmHG.
- The uterine muscle is an involuntary smooth muscle, arranged multi-directionally. With contractions, the upper segment thickens and the lower segments thins, pushing the fetus downwards and forcing the cervix open.
7
Q
Second stage of labour
A
- At start of second stage the mother has an urge to bear down with each contraction. Abdominal pressure and uterine contractile force combines to expel the fetus.
- In this stage, fetal descent must be closely monitored. Fetus does throught the following motions.
- Descent, flexion, internal rotation, extension, external rotation, expulstion
- This stage usually take 30mins-3hrs in primigravida women and 5-30mins in multigravida.
8
Q
Mechanism of labour (6 movements of the fetus)
A
- Descent - fetus moves down due to force of uterine contraction, maternal bearing-down efforts, and gravity if patient is upright.
- Flexion - partial flexion is already present before labour. During descent resistance from cervix and pelvic causes further flexion of cervixal spine, with baby’s chin approaching its chest. The purpose of this is to change the presenting head diameter to a smaller one.
- Internal rotation - In occipitoanterior position, fetal head turns so that the back of the head faces the symphysis pubis. Internal rotation occurs as the fetal head meets the muscular sling of the pelvic floor.
- Extension - flexed head in occipitoanterior position continues descent. Since vaginal outlet is directed upward & forward, extension is needed for head to pass through. As head continues to descend there is a bulging of the perineum followed by crowing ( when largest diameter of the head is encircled by vulvar ring).
- External rotation - In both OA and OP position, the delivered head returns to original position at time of engagement to align with fetal back and shoulders.
- Expulsion - After external rotation of the head, the anterior shoulder delivers under the symphysis pubis, followed by the posterior shoulder over the perineal body, and the body of the child.
9
Q
Third stage of labour
A
- Delivery of the placenta.
- Immediately following delivery of the baby, the cervix and vagina should be thoroughly inspected for lacerations and surgical reparis should be preformed if needed.
- Delivery of the placenta usually occurs within 2-10 mins of the end of the second stage. (Should occur within 30mins max)
10
Q
Signs of Placental Separation
A
- Fresh show of blood from vagina
- Umbilical cord lengthens outside of vagina
- Fundus of uterus rises up
- Uteus becomes firm and globular
- Only once these signs occur should you attempt traction on the cord (pull gently with counterpressure between symphysis and fundus to prevent uterine descent).
- Should administer 20U of oxytocin after the placenta has been delivered. Oxycotin is a uterotonic agent that causes uterine contractions and prevents postpartum hemorrhage.
11
Q
Fourth stage of labour
A
- Hour following delivery.
- Requires close observation of the patient.
- Monitor BP, Pulse, and Uterine blood loss
12
Q
Induction and augmentation of labour
A
- Induction - process where labour is initiated by artifical means
- Induction of labour involved 2 processes
- Mechanism to promote cervical ripening (effacement and softening) - local application of postaglandins, intrauterine placement of catheters, use of osmotic dilators.
- Initiation of uterine contractions - oxytocin
- Induction of labour involved 2 processes
- Augmentation - artificial stimlation of labour that has begun spontaneously
13
Q
Indications for induction
A
- Only indicated when continuation of pregnanacy represents significant risk to fetus or mother. Inducation may be indicated at term in the case of premature rupture of the membranes.
14
Q
Continuous Electronic Fetal Monitoring
A
- Electronic fetal monitoring allows for the continuous reporting of fetal heart rate (FHR) & uterine contractions by means of a monitor that prints results on a 2-channel strip chart recorder.
- Can be obtained using an external transducer or through internal monitoring -> internal monitoring gives more precise measurements.
15
Q
Baselines assessment FHR
A
- Assessment of FHR depends on the evalutation of the baseline pattern and periodic changes related to uterine contractions. Can be divided into short-term or long-term variability.
- Short-term - interval between either successive fetal ECG signals or mechanical events of teh cardiac cycle. Normally flutuates between 5 & 25 BPM. Variability of <5BPM = severe fetal distress.
- Long-term - flutuations in frequency and amplitudes of change in the baselines rate. Normally it is 3-10 cycles per minute.
- Normal FHR during labour = 110-160 BPM with variability of 5-25BPM
