WEEK 3 🤰 EXAM CONTENT Flashcards
Discuss physiology of Contraction and Retraction
Uterine contractions triggered by oxytocin, prostaglandins+elec signals that cause smoooth muscles of uterus to shorten. This helps dilate cervix +push fetus down.
Contractions r coordinated by gap junctions between muscle cells allowing myometrium to contract in synchronised manner
Retraction is where uterine muscles shorten + thicken which pulls cervix upwards aiding in its effacement and dilation
Discuss physiology of Fundal Dominance:
Contractions start in cornua, pass inwards+down in waves
-Last longest + most intense in fundus (UUS)
-UUS contracts+retracts powerfully to expel fetus and apply pressure on cervix to efface+dilate
-Weakest in LUS
-LUS contracts only slightly + dilates
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Discuss physiology of Active UUS and Passive LUS in labour
UUS (fundus) is active as it generates strong contractions that force the bb downwards, aiding descent and dilation of C
LUS (bottom) doesnt actively contract like UUS. It undergoes effacement as UUS pulls on it. It stretches to allow space for bb.
Discuss physiology of retraction
Its a state of permanent shortening of muscle fibres
-After the fundus contracts, the muscle fibres dont completely relax but shorten + thicken, pulling upwards on the LUS, this stretches the LUS and therefore aids in effacement and dliation of the cervix and OS uteri.
-It also forces pressure on the fetus, by reducing space in UUS aiding in fetal descent.
Retraction is essential for labour progression
Discuss the physiology of the formation of the retraction ring:
Its a ridge that forms btween thick retracted muscles of UUS and thin lower distended LUS.
The ring gradually rises as UUS contracts+retracts abd the LUS thins out to accomodate descending fetus
Once cervix fully dilated + fetus can leave uterus, ring rises no further
-Helps indicate uterus is contracting properly
Discuss physiology of polarity of the uterus:
Term 2 describe neuromuscular harmony that prevails btween 2 poles/segments of the uterus throughout labour.
During each contraction, poles act harmoniously.
Upper pole contracts strongly + retracts to expel fetus
Lower pole contracts slightly + dilates to allow expulsion to take place
The rhythmical coordination btween UUS + LUS is polarity
Disorganisation of polarity may inhibit labour.
Discuss physiology of Intensity of amplitude of contractions:
-Contractions cause rise in intrauterine pressure.
-Measured in mmHg by pressure they exert on amniotic fluid.
-Intrauterine hydrostatic pressure is pressure inside uterus due to amniotic fluid bb etc.
Early labour amplitude= 20mmHg, 20-30secs every 15-20mins
Progression of labour amplitude= 60mmHg, 45-60secs every 2-3mins
Resting tone= 4-10mmHg
Discuss physiology of resting tone in labour.
Resting tone btween contractions is 4-10mmHg
The uterus is never completley relaxed
During contractions blood flow to placenta is limited
0 +C02 exchange in inner vilus spaces is impeded
Low resting tone is vital for adequate feetal oxygenation
It ensures uterus stays ready for contractions + maintains stability of fetal position
Discuss physiology of formation of fore and hindwaters
-As LUS stretches + cervix effaces, chorion detaches from decidua
-The increased intrauterine pressure causes loosened part of sac of fluid to bulge down into internal os at depth of6-12cm
-Fetus’s head fits snugly into cervix + cuts off fluid infront of head from fluid surrounding body.
-These are the fore and hind waters
What does separation of fore and hindwaters do?
Forewaters aid effacement
+ dilation of cervix/os
-Hindwaters help equalise pressure in uterus during contractions, protecting fetus + placenta.
-Prevents pressure thats applied to hindwaters from being applied to forewaters.
This helps membranes to stay intact for longer preventing infection
Discuss physiology of ROM’s
-Rupture as result of increased prostaglandin E2 in amnion in labour + force of contractions causing pressure inside forewaters + lessening of support as cervix dilates.
In normal labour ROM’s occurs toward end of 1st stage when cervix cant support forewaters + contractions.
Discuss physiology of Show in labour
Result of effacement+dilation of cervix.
-Operculum (plug) is shed per vaginum
-Bloodstained mucoid discharde a few hrs b4/after labour starts
Blood comes from ruptured capillaries in parietal decidua where chorion has become detached from dilating cervix
OR from VE.
Discuss physiology of Fetal Axis Pressure in childbirth
During each contraction, uterus rises forward + force of fundal contractions is transmitted to upper pole of fetus, down long axis of fetus, + applied by presenting part to cervix.
This helps dilate cervix and helps fetal descent.
Also helps stimulate uterine contractions which progresses labour.
More significant after ROM’s + during 2nd stage.
Write a note on Purple Line
Purple line that shows during labour and is said to signifify dilation.
Begins at anal margin at start of labour, gradually creeps up
Reaches nape of buttocks (sacroccocygeal joint) womans fully dilated
Can be used as a measure of cervical dilation when womans in all fours
Write a note on Leopold’s Manoevour
Systematic 4-step method 4 palpating uterus to deterimine
-Lie
-Presentation
-Engagement
-Position
Feel fundus, sides, just above pubic bone, lower abdomen.
Entire head above pubis symphysis = 5/5 palpable or 0/5 engaged
Write a note on the Sacral Bulge
Bulging of saccrum + coccyx due to pressure of descending fetall part.
Can be seen on womans lower back in a protuding triangle shape.
It happens as fetus moves throu birth cana; + pushes against soft tissyes + bony structure of maternal pelvis.
List the indications for a VE
-Confirm onset of labour
-Establish a baseline for further progress
-Assess progress of dilation + effacement
-Diagnose presentation
-Rule out cord-prolapse after SROM
-Confirm full dilation
-To confirm axis presentation of 2nd twin in multiple pregnancies
Discuss contraindications/and/or/risks for VE (UNFINISHED)
-Placenta previa (placenta covering/near cervix)
-Acute vaginal bleeding
-Risk of infection
-Risk of ROM’s
