OB-GYN Revision 4 Flashcards
It is important to know how the circumference of the fetal head varies with different degrees of neck flexion:
Suboccipitobregmatic (vertex, flexed) is [] cm
Occipitofrontal (vertex, neutral flexion) is [] cm
Submentobregmatic (face) is [] cm
Verticomental (brow) is [] cm
Suboccipitobregmatic (vertex, flexed) is 9.5cm
Occipitofrontal (vertex, neutral flexion) is 11.0cm
Submentobregmatic (face) is 9.5cm
Verticomental (brow) is 13.5cm
Stage 1: Descent
- What processes encourage fetus descent? [4]
Descent is encouraged by:
* Increased abdominal muscle tone
* Braxton hicks in the late stages of pregnancy
* Fundal dominance of the uterine contractions during labour
* Increased frequency and strength of contractions during labour
Describe the process of descent of the fetus [2]
The fetus descends into the pelvis:
* As the head descends, it moves towards the pelvic brim in either the left or right occipito-transverse position (this means the occiput can be facing the left side or right side of the mother’s pelvis).
Describe the process of engagament of the fetus [2]
How can you tell that engagement has occurred? [1]
This is when the largest diameter of the fetal head descends into the maternal pelvis.
- The term engagement is referring to the widest part of the fetal head successfully negotiating its way down deep into the maternal pelvis in the R/L occipto-transverse position
- Engagement is identified by abdominal palpation, where the fetal head is 3/5th palpable or less.
Describe the process of flexion of baby during labour [2]
As the fetus descends through the pelvis, fundal dominance of uterine contraction exerts pressure down the fetal spine towards the occiput, forcing the occiput to come into contact with the pelvic floor
- When this occurs the fetal neck flexes (chin to chest) allowing the circumference of the fetal head to reduce to sub-occipitobregmatic (9.5cm).
Describe the process of internal rotation during labour [2]
When does this part occur during labour? [1]
The pelvic floor has a gutter shape with a forward and downward slope, encouraging the fetal head to rotate from the left or right occipito-transverse position a total of 90-degrees, to an occipital-anterior (occiput facing forward) position, to lie under the subpubic arch.
- This rotation will occur during established labour and it is commonly completed by the start of the second stage
Describe the process of the extension of the presenting part [2]
The occiput slips beneath the suprapubic arch allowing the head to extend. The fetal head is now born and will be facing the maternal back with its occiput anterior.
Describe the process of crowning during labour [1]
When the widest diameter of the fetal head successfully negotiates through the narrowest part of the maternal bony pelvis, the fetal head is considered to be ‘crowning’.
- This is clinically evident when the head, visible at the vulva, no longer retreats between contractions.
Descrine the process of external rotation & restitution during labour
Because the shoulders at the point of the head being delivered are only just reaching the pelvic floor they are often still negotiating the pelvic outlet and the fetus may naturally align its head with the shoulders.
This is called restitution and visually you may see the head externally rotate to face the right or left medial thigh of the mother.
Delivery of the shoulders and body during labour? [1]
Downward traction by the healthcare professional will assist the delivery of the anterior shoulder below the suprapubic arch.
This is followed by upward traction assisting the delivery of the posterior shoulder.
When is IOL offered with regards to length of gestation [1]
IOL is offered between 41 and 42 weeks gestation.
Induction of labour is also offered in situations where it is beneficial to start labour early, such as: [6]
- Prelabour rupture of membranes
- Fetal growth restriction
- Pre-eclampsia
- Obstetric cholestasis
- Existing diabetes
- Intrauterine fetal death
What is the Bishop score? [1]
What is max/min score? [1]
What 5 things are assessed when calculating the Bishop score? [1]
The Bishop score is a scoring system used to determine whether to induce labour.
- Min: 0
- Max: 13
Asssessed via
* Fetal station (scored 0 – 3)
* Cervical position (scored 0 – 2)
* Cervical dilatation (scored 0 – 3)
* Cervical effacement (scored 0 – 3)
* Cervical consistency (scored 0 – 2)
A score of [] or more predicts a successful induction of labour. A score below this suggests cervical ripening may be required to prepare the cervix.
A score of 8 or more predicts a successful induction of labour. A score below this suggests cervical ripening may be required to prepare the cervix.
Describe the different methods for inducing labour [4]
membrane sweep:
- examining finger passing through the cervix to rotate against the wall of the uterus, to separate the chorionic membrane from the decidua
- membrane sweeping is regarded as anadjunct to induction of labour rather than an actual method of induction
- if successful, should produce the onset of labour within 48 hours.
- can occur in antenatal clinic
amniotomy (‘breaking of waters’)
Vaginal prostaglandin E2 (dinoprostone):
- inserting a gel, tablet (Prostin) or pessary (Propess) into the vagina.
- The pessary is similar to a tampon, and slowly releases local prostaglandins over 24 hours.
- Done in hospital
oral prostaglandin E1
* also known as misoprostol
Cervical ripening balloon (CRB)
- silicone balloon that is inserted into the cervix and gently inflated to dilate the cervix
Artificial rupture of membranes with an oxytocin infusion:
- would only be used where there are reasons not to use vaginal prostaglandins.
- iut can be used to progress the induction of labour after vaginal prostaglandins have been used.
What are the names for oral prostaglandin E1 and vaginal prostaglandin E2?
vaginal prostaglandin E2 (PGE2):
- also known as dinoprostone
oral prostaglandin E1
- also known as misoprostol
NICE guidelines
if the Bishop score is ≤ 6
- which methods of IOL are used? [3]
if the Bishop score is > 6
- which methods of IOL are used? [2]
if the Bishop score is ≤ 6
* vaginal prostaglandins or oral misoprostol
* mechanical methods such as a balloon catheter can be considered if the woman is at higher risk of hyperstimulation or has had a previous caesarean
if the Bishop score is > 6
* amniotomy and an intravenous oxytocin infusion
Women are monitored for their progress in the first stage of labour using a partogram
There are two lines on the partogram that indicate when labour may not be progressing adequately. These are labelled [2]
Describe them [2]
There are two lines on the partogram that indicate when labour may not be progressing adequately. These are labelled “alert” and “action”
- The Alert line starts at 4 cm of cervical dilatation and it travels diagonally upwards to the point of expected full dilatation (10 cm) at the rate of 1 cm per hour
- The Action line is parallel to the Alert line, and 4 hours to the right of the Alert line
When it takes too long for the cervix to dilate, the readings will cross to the right of the alert and action lines.
How can you manage shoulder dystocia:
- Non surgically [4]
- Surgically [2]
McRoberts’ manoeuvre:
- entails flexion and abduction of the maternal hips, bringing the mother’s thighs towards her abdomen
- increases the relative anterior-posterior angle of the pelvis and often facilitates a successful delivery
Pressure to the anterior shoulder:
- involves pressing on the suprapubic region of the abdomen. This puts pressure on the posterior aspect of the baby’s anterior shoulder, to encourage it down and under the pubic symphysis.
Rubins manoeuvre:
- reaching into the vagina to put pressure on the posterior aspect of the baby’s anterior shoulder to help it move under the pubic symphysis.
Wood’s screw manoeuvre
- is performed during a Rubins manoeuvre.
- the other hand is used to reach in the vagina and put pressure on the anterior aspect of the posterior shoulder
- The top shoulder is pushed forwards, and the bottom shoulder is pushed backwards, rotating the baby and helping delivery.
- If this does not work, the reverse motion can be tried, pushing the top shoulder backwards and the bottom shoulder forwards.
Surgical:
- Episiotomy
- C-section
What is a key sign of shoulder dystocia? [1]
The turtle-neck sign is where the head is delivered but then retracts back into the vagina.
Which drug is used during PCA for labour? [1]
What are AEs? [2]
Which drugs are used to reverse these AEs? [2]
intravenous remifentanil
- need access to naloxone for respiratory depression, and atropine for bradycardia
Describe how an epidural is given [1]
Which drugs are used? [3]
- inserting a small tube (catheter) into the epidural space in the lower back (outside the dura mater, separate from the spinal cord and CSF)
- Local anaesthetic medications are infused through the catheter into the epidural space: including levobupivacaine or bupivacaine, usually mixed with fentanyl.
The key risks to remember to the baby are:
[] with ventouse
[] with forceps
The key risks to remember to the baby are:
Cephalohaematoma with ventouse ( blood that collects between a newborn’s scalp and skull)
Facial nerve palsy with forceps
10 - 13+6 weeks
11 - 13+6 weeks
