OB-GYN Revision 4

Question 1

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

Answer 1

Suboccipitobregmatic (vertex, flexed) is 9.5cm
Occipitofrontal (vertex, neutral flexion) is 11.0cm
Submentobregmatic (face) is 9.5cm
Verticomental (brow) is 13.5cm

Question 2

Stage 1: Descent
- What processes encourage fetus descent? [4]

Answer 2

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

Question 3

Describe the process of descent of the fetus [2]

Answer 3

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).

Question 4

Describe the process of engagament of the fetus [2]

How can you tell that engagement has occurred? [1]

Answer 4

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.

Question 5

Describe the process of flexion of baby during labour [2]

Answer 5

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).

Question 6

Describe the process of internal rotation during labour [2]
When does this part occur during labour? [1]

Answer 6

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

Question 7

Describe the process of the extension of the presenting part [2]

Answer 7

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.

Question 8

Describe the process of crowning during labour [1]

Answer 8

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.

Question 9

Descrine the process of external rotation & restitution during labour

Answer 9

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.

Question 10

Delivery of the shoulders and body during labour? [1]

Answer 10

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.

Question 11

When is IOL offered with regards to length of gestation [1]

Answer 11

IOL is offered between 41 and 42 weeks gestation.

Question 12

Induction of labour is also offered in situations where it is beneficial to start labour early, such as: [6]

Answer 12

• Prelabour rupture of membranes
• Fetal growth restriction
• Pre-eclampsia
• Obstetric cholestasis
• Existing diabetes
• Intrauterine fetal death

Question 13

What is the Bishop score? [1]
What is max/min score? [1]

What 5 things are assessed when calculating the Bishop score? [1]

Answer 13

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)

Question 14

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.

Answer 14

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.

Question 15

Describe the different methods for inducing labour [4]

Answer 15

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

Osmotic dilator (cervical rods)
* You may hear these called cervical ripening rods or Dilapan-S. Thin rods are put inside your cervix for up to 24 hours. They act like sponges, taking in fluid from the surrounding tissue.

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.

Question 16

What are the names for oral prostaglandin E1 and vaginal prostaglandin E2?

Answer 16

vaginal prostaglandin E2 (PGE2):
- also known as dinoprostone

oral prostaglandin E1
- also known as misoprostol

Question 17

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]

Answer 17

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

Question 18

What are criteria for uterine hyperstimulation? [2]

Answer 18

• Individual uterine contractions lasting more than 2 minutes in duration
• More than five uterine contractions every 10 minutes

Question 19

What can uterine hyperstimulation lead to? [3]

Answer 19

• intermittent interruption of blood flow to the intervillous space over time may result in fetal hypoxemia and acidemia
• Emergency caesarean section
• Uterine rupture

Question 20

Delay in the first stage of labour is considered when there is either: [2]

Answer 20

• Less than 2cm of cervical dilatation in 4 hours
• Slowing of progress in a multiparous women

Question 21

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]

Answer 21

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.

Question 22

What does crossing the alert line [2] and action line [1] on a partogram indicate?

Answer 22

Crossing the alert line is an indication for amniotomy (artificially rupturing the membranes) and a repeat examination in 2 hours

Crossing the action line means care needs to be escalated to obstetric-led care and senior decision-makers for appropriate action.

Question 23

Delay in the second stage is when the active second stage (pushing) lasts over:

[] hours in a nulliparous woman
[] hour in a multiparous woman

Answer 23

Delay in the second stage is when the active second stage (pushing) lasts over:

2 hours in a nulliparous woman
1 hour in a multiparous woman

Question 24

What are the key risk factors for shoulder dystocia? [4]

Answer 24

• fetal macrosomia (hence association with maternal diabetes mellitus)
• high maternal body mass index
• diabetes mellitus
• prolonged labour

Question 25

How can you manage shoulder dystocia: - Non surgically [4] - Surgically [2]

Answer 25

**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**

Question 26

What is a key sign of shoulder dystocia? [1]

Answer 26

The **turtle-neck sign** is where the head is delivered but then retracts back into the vagina.

Question 27

What is the MoA of ergometrine? [1] When is it indicated? [2]

Answer 27

**Ergometrine** * **MoA**: It stimulates smooth muscle contraction, both in the uterus and blood vessels. * **Indications**: third stage of labour and to treat post-partum haemorrhage

Question 28

Name three side effects of ergometrine [3] Which condition is it contra-indicated in? [1]

Answer 28

Due to the action on the **smooth muscle** in **blood vessels and gastrointestinal tract**, it can cause several side effects, including **hypertension, diarrhoea, vomiting and angina.** - Therefore needs to be **avoided in eclampsia**, and used only with significant caution in patients with hypertension.

Question 29

What is the MoA of misoprostol? [1] When is it indicated? [3]

Answer 29

**Misoprostol** is a **prostaglandin analogue**, meaning it binds to prostaglandin receptors and activates them. It is used as **medical management in miscarriage**, to help **complete the miscarriage**. Misoprostol is used alongside **mifepristone** for **abortions**, and **induction of labour after intrauterine fetal death.**

Question 30

Describe the MoA of mifepristone [1] When is it indicated? [1]

Answer 30

**Mifepristone** is an **anti-progestogen medication** that **blocks** the action of **progesterone**, **halting** the **pregnancy and ripening the cervix.** - It therefore **enhances** the effects of **prostaglandins** to **stimulate** **contraction** of the **uterus** - Misoprostol is used alongside **mifepristone** for **abortions**, and **induction of labour after intrauterine fetal death.** | It is not used during pregnancy with a healthy living fetus.

Question 31

What is the MoA of Terbutaline? [1] When is it indicated? [1]

Answer 31

**Terbutaline** is a **beta-2 agonist,** similar to salbutamol - It acts on the **smooth** **muscle** of the **uterus** to **suppress uterine contractions** - It is used for **tocolysis** in **uterine** **hyperstimulation**, notably when the **uterine contractions become excessive** during **induction** of **labour**.

Question 32

What is the MoA of carboprost? [1] When is it indicated? [1]

Answer 32

**Carboprost** is a **synthetic prostaglandin analogue**, meaning it binds to prostaglandin receptors. **It stimulates uterine contraction** It is given as a deep intramuscular injection in **postpartum** **haemorrhage**, where **ergometrine and oxytocin have been inadequate**

Question 33

Describe the pain relief that is available in labour [4]

Answer 33

**1. Simple analgesia:** - Paracetamol - Codeine - *NSAIDs are avoided* **2. Gas and Air**: - 50% nitrous oxide and 50% oxygen - used during contractions **3. Intramuscular Pethidine or Diamorphine**: - Opiods given IM - help with anxiety and distress - may cause drowsiness or nausea in the mother, and can cause respiratory depression in the neonate if given too close to birth **Patient Controlled Analgesia**: - intravenous remifentanil.

Question 34

Which drug is used during PCA for labour? [1] What are AEs? [2] Which drugs are used to reverse these AEs? [2]

Answer 34

**intravenous** **remifentanil** - need access to **naloxone** for **respiratory** **depression**, and **atropine** for **bradycardia**

Question 35

Describe how an epidural is given [1] Which drugs are used? [3]

Answer 35

- 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.**

Question 36

What are the main side effects of epidural? [2]

Answer 36

**Increased probability of instrumental delivery** Women need urgent anaesthetic review if they **develop significant motor weakness** - The catheter may be incorrectly sited in the **subarachnoid space** (within the spinal cord), rather than the epidural space.

Question 37

A baby is born using instrumental delivery. Which drug is given to reduce the risk of maternal infection? [1]

Answer 37

A single dose of **co-amoxiclav** is recommended after instrumental delivery to reduce the risk of maternal infection.

Question 38

What are 4 key indications of performing instrumental delivery? [5]

Answer 38

Failure to progress Fetal distress Maternal exhaustion Control of the head in various fetal positions **TOM TIP:** It is worth remembering there is an increased risk of requiring an instrumental delivery when an epidural is in place for analgesia.

Question 39

The key risks to remember to the baby are: **[]** with ventouse **[]** with forceps

Answer 39

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

Question 40

Forceps delivery can leave **bruises** on the baby’s face. Rarely the baby can develop **[]**. What does this lead to? [1] .

Answer 40

Forceps delivery can leave bruises on the baby’s face. Rarely the baby can develop **fat necrosis**, leading to **hardened lumps of fat on their cheeks**. Fat necrosis resolves spontaneously over time.

Question 41

Which nerve injuries to the mother can be caused by instrumental deliveries [2] How would these present? [2]

Answer 41

**Femoral nerve**: - **compressed** against the **inguinal** **canal** during a **forceps** delivery. - Injury to this nerve causes **weakness of knee extension**, **loss** of the **patella** **reflex** and **numbness of the anterior thigh and medial lower leg**. **Obturator nerve** - forceps or by the head of baby - Injury causes weakness of **hip adduction and rotation**, and **numbness of the medial thigh**.

Question 42

Answer 42

**10 - 13+6 weeks**

Question 43

Answer 43

11 - 13+6 weeks

Question 44

Describe how you would tell a patient why you would IOL?

Answer 44

“Usually, labour will occur naturally and start between 37 and 42 weeks. If we believe that continuing the pregnancy at any point might involve significant risks for either you or your baby, we may offer you an induction of labour. This is when interventions are used to help start the labour process before it has started on its own.” “I will now explain some of the reasons why induction of labour is offered, but before I do, do you have any questions so far?”

Question 45

Describe some different indications for IOL? [4]

Answer 45

**Prolonged gestation** * Prolonged gestation is when a pregnancy lasts longer than 41 weeks.2 It is the most common reason for inducing labour.3 * “If your pregnancy goes beyond 41 weeks, there is a higher risk of complications, including caesarean section, neonatal unit admission and stillbirth.” **Prelabour rupture of membranes** * “During pregnancy, your baby is surrounded by a bag of fluid (also called your waters). If your waters break more than 24 hours before labour starts, there is a higher risk of infection for both you and your baby. We may recommend an induction of labour to reduce this risk, but this will be dependent on how far into the pregnancy you are.” 1,4 **Maternal health conditions** * “An induction may be advised if you have a medical condition that makes it safer for you and your baby to deliver earlier. For example, diabetes, high blood pressure or heart disease.” 1 * “If you have diabetes, induction of labour is suggested to reduce the risk of stillbirth. It can also help to prevent the baby from growing too big, which can increase the risk of the baby becoming stuck during birth.” 2 **Concern for baby’s wellbeing** * “If there is any concern about the baby’s health or growth, we may suggest induction to shorten the pregnancy and reduce risk to the baby.”

Answer 46

**Advantages of induction of labour** * The advantages depend on the indication, with the intention to reduce the risk of complications for the woman or baby (or both) by delivering earlier. * Induction of labour at 41 weeks gestation is associated with a lower risk of perinatal death compared to continuing the pregnancy beyond 41 weeks. **Disadvantages of induction of labour** * Induction of labour is a medical process that may affect other birth choices and the perception of labour and birth. E.g. induction usually means giving birth in a labour ward rather than a midwifery-led unit, and options such as a birthing pool may not be available. * Induced labour may be more painful than spontaneous labour and may mean a longer stay in hospital.2

Question 47

What are contraindications for IOL? [3]

Answer 47

Inducing labour is unsuitable when vaginal delivery poses significant risks or is not feasible. E.g. **placenta** **praevia**, **transverse fetal lie or if the mother or baby may be unable to tolerate labour** (e.g. significant maternal cardiac disease or some cases of fetal growth restriction). Induction is generally **not recommended for breech presentations due to increased complexities**. **Women who have undergone caesarean sections or uterine surgeries** require careful consideration. Inducing labour in these circumstances increases the **risk of uterine scar rupture**, especially when **prostaglandins** are **used**. **Mechanical methods are often preferred in such situations**. Induction can still be offered after consultant assessment, ensuring the mother is fully informed of the risks.5

Question 48

Name a disadvantage of using prostaglandins for IOL [3]

Answer 48

“Sometimes these hormones can cause contractions that are too frequent or that last too long. This is known as **hyperstimulation**. This can be painful and can mean that the baby becomes distressed if there is not enough rest between contractions. It is also possible for the womb to be injured, although this is not common.2 We will monitor you throughout, and if hyperstimulation does occur, the induction process will be stopped, and medication can be given to slow the contractions.” “Hormonal induction is **not suitable for some women, such as those who have had a previous caesarean section**, are at a higher risk of hyperstimulation or choose to use a mechanical method.” “Some women may experience side effects from the hormones, especially if taken by mouth. **These include nausea, vomiting and diarrhoea**.” 9

Question 49

If prostaglandins are not suitable or have not been successful in inducing labour, women may be offered alternative methods, like a balloon catheter or osmotic cervical dilator. What are ad/disadvantages of these? [2]

Answer 49

**Advantages** * “Mechanical techniques are less likely to cause hyperstimulation than hormonal induction.” * “They are a minimally invasive option and do not require medications. Some women can safely use this method whilst at home.” 9 **Disadvantages** * “The insertion of the balloon may be uncomfortable and cause cramping.” * “The induction process may take longer compared to other methods.” * “There is a small risk that the umbilical cord can pass through the cervix. This is called a cord prolapse, which can reduce blood flow to the baby. This is an emergency and requires immediate intervention to prevent any harm to the baby.” 9 Amniotomy

Question 50

Describe how you would describe an amniotomy [1] What are advantages / disadvantages of this? [2]

Answer 50

“An amniotomy is when your doctor or midwife will use a small, thin tool to break the sac of fluid that surrounds your baby. This is done through the vagina and can help to speed up labour. Often a hormone drip is given alongside.” **Advantages** * “Breaking the waters can release hormones that help to make your contractions start, or make them more frequent and stronger.” * “This procedure is necessary before considering the hormone drip to help the contractions (oxytocin).” **Disadvantages** * “Amniotomy is done during a vaginal examination, and the examination can be uncomfortable. The midwife or doctor performing the examination will discuss pain relief options (such as gas and air) with you.”

Question 51

Describe how oxytocin works for the IOL. What are advantages / disadvantages? [2]

Answer 51

Oxytocin is used to increase both the frequency and strength of contractions. It is given as an intravenous infusion, usually only once the membranes have been ruptured. “Oxytocin is a hormone that increases the number and strength of contractions. It is given through a drip into a vein in your arm or hand. It can be started immediately after breaking the waters, or after a period time if contractions do not start on their own.” Advantages “Oxytocin increases the number and strength of the contractions that are needed for labour to progress.” Disadvantages “Oxytocin can make contractions more painful. Your midwife or doctor will discuss pain relief options with you.” “If you are receiving an oxytocin drip, your baby’s heartbeat should be continuously monitored. This is likely to mean that certain birth choices are not available to you, such as giving birth in a midwifery-led unit or in a birthing pool.”