Obstetrics: Labour & Delivery 2 Flashcards
What do we mean by instrumental delivery?
Vaginal delivery using instruments to assist e.g. ventouse suction cup or forceps
Where is instrumental delivery usually performed?
Can be done on labour ward but if concerns about whether it will be successful may move woman to theatre so than caesarean can be rapidly performed if necessary
State some indications for instrumental delivery
- Failure to progress
- Fetal distress
- Maternal exhaustion
- Control of the head in various fetal positions
What method of pain relief increases risk of requiring an instrumental delivery?
Epidural
Describe how a ventouse works
What is main complication with ventouse delivery?
- Basically a suction cup that goes on baby’s head (flexion point of head). During contraction doctor or midwife gently pulls baby out of vagina
- Main complication= cephalohaematoma
Describe how forceps work
What is the main complication of forceps delivery?
- Forceps look like large metal salad tongs. They come as two pieces of curved metal that attach together, go either side of the baby’s head and grip the head in a way that allows the doctor or midwife to apply careful traction and pull the head from the vagina.
- Main complication= facial nerve palsy → facial paralysis on one side
*NOTE: can leave bruises on baby’s face and rarely cause fat necrosis of cheeks- leaving hard lumps on cheeks- resolves spontaneously over time
What is recommended following instrumental delivery to reduce risk of infection in mother?
Single dose co-amoxiclav
State some potential complications/risks associated with instrumental delivery in the mother
- Postpartum haemorrhage
- Infection
- Episiotomy
- Perineal tears
- Injury to the anal sphincter
- Incontinence of the bladder or bowel
- Nerve injury
- Femoral (may be compressed against inguinal canal during forceps delivery → weakness knee extension, loss patella reflex, numbness anterior thigh & medial leg)
- Obturator (may be compressed by forceps delivery or fetal head in normal delivery → weakness hip adduction, rotation and numbness medial thigh)
State some potential complications/risks associated with instrumental delivery in the baby
The key risks to remember to the baby are:
- Cephalohaematoma with ventouse
- Facial nerve palsy with forceps
Rarely there can be serious risks to the baby:
- Subgaleal haemorrhage (most dangerous)
- Intracranial haemorrhage
- Skull fracture
- Spinal cord injury
What 3 other nerve injuries may occur during birth that are usually unrelated to instrumental delivery?
- Lateral cutaneous nerve of the thigh: prolonged flexion at hip while in lithotomy position can cause injury → numbness anterolateral thigh
- Lumbosacral plexus: compressed by fetal head → foot drop & numbness of anterolateral thigh, lower leg & foot
- Common peroneal nerve: compressed on head of fibula while in lithotomy position → footdop & numbness in lower lateral leg
What is a caesarean section?
A Caesarean section is the delivery of a baby through a surgical incision in the abdomen and uterus.
State some indications for elective caesarean sections
- Previous caesarean
- Symptomatic after a previous significant (3rd/4th degree) perineal tear
- Placenta praevia
- Vasa praevia
- Breech presentation
- Other malpresentation
- Multiple pregnancy when first twin not in cephalic position
- Uncontrolled HIV infection
- Primary genital herpes in 3rd trimester
- Cervical cancer
*NOTE: elective caesarean sections usually planned for after 39 weeks
Describe the 4 categories of emergency caesareans
- Category 1: There is an immediate threat to the life of the mother or baby. Decision to delivery time is 30 minutes.
- Category 2: There is not an imminent threat to life, but caesarean is required urgently due to compromise of the mother or baby. Decision to delivery time is 75 minutes.
- Category 3: Delivery is required, but mother and baby are stable.
- Category 4: This is an elective caesarean, as described above.
What are most common reasons for caesarean section?
- Failure to progress
- And/or suspected/confirmed fetal compromise
What kind of anaesthetic is used in caesarean sections and how does it work?
Spinal anaesthetic
Injection of local anaesthetic (e.g. lidocaine) into CSF in lower back which blocks nerves from abdomen downwards
What layers do you have to go through when giving a spinal anaesthetic?
*Recap Yr3 surgery
- Skin
- Subcutaneous fat
- Supraspinous ligament
- Interspinous ligament
- Ligamentum flavum
- Epidural space
- Dura
- Subdural space
- Arachnoid layer
… into SA space
Why is spinal anaesthesia preferred to general anaesthetic in caesarean sections?
- Safer
- Fewer complications
- Faster recovery
State some potential complications/risks associated with spinal anaesthetics
- Pain during injection
- Itching
- Allergic reactions or anaphylaxis
- Hypotension
- Headache
- Urinary retention
- Nerve damage (rare)
- Haematoma
What is required pre-operatively before caesarean section?
- Bloods: FBC, G&S
- Prescribe H2 agonist
- Risk assessment & prophylaxis for VTE
- Catheter insertion
Transverse lower uterine segment incisions are most commonly used in caesareans; state & describe the two possible transverse lower uterine incisions and state which is recommended
- Pfannenstiel incision: a curved incision two fingers width above the pubic symphysis
- Joel-cohen incision: a straight incision that is slightly higher (recommended incision)
Other than the two most common incisions, what other incision may be used in a caesarean section?
Vertical incision
E.g. very premature deliveries, anterior placenta praevia
After initial incision, blunt dissection is used; why?
- Less bleeding
- Shorter operating times
- Less risk of injury to baby
What layers do you have to dissect through when doing a caesarean section?
- Skin
-
Subcutaneous tissue
- Camper’s fascia (superficial layer)
- Scarpa’s fascia (deep layer)
- Rectus sheath (the aponeurosis of the transversus abdominis and external and internal oblique muscles)
- Rectus abdominis muscles (separated vertically- CHECK!!)
- Transversalis fascia
- Parietal peritoneum
- Visceral peritoneum (and bladder) – the bladder is separated from the uterus with a bladder flap
- Uterus (perimetrium, myometrium and endometrium)
- Amniotic sac
Once you have dissected through the amniotic sac, how is the baby delivered?
Pull out with assistance of pressure of fundus. Can use forceps if needed.
How is the uterus closed following caesarean section?
- Closed whilst inside abdomen using 2 layers of sutures
- Exteriorisation (taking uterus out of the abdomen) avoided if possible
- Closure of skin & abdomen
Elective caesarean sections are generally considered a very safe and routine procedure but emergency caesarean sections have a higher risk of complications; true or false?
True as they are usually performed in less controlled settings and for more acute indications (e.g. fetal distress).
Complications of caesarean sections can categorised as:
- Generic surgery risks
- Damage to local structures
- Effects on abdominal organs
- Effects on baby
- Complications in post-partum period
- Effects on future pregnancy
*
Generic surgical risks:
- Bleeding
- Infection
- Pain
- Venous thromboembolism
Complications in the postpartum period:
- Postpartum haemorrhage
- Wound infection
- Wound dehiscence
- Endometritis
Damage to local structures:
- Ureter
- Bladder
- Bowel
- Blood vessels
Effects on the abdominal organs:
- Ileus
- Adhesions
- Hernias
Effects on future pregnancies:
- Increased risk of repeat caesarean
- Increased risk of uterine rupture
- Increased risk of placenta praevia
- Increased risk of stillbirth
Effects on the baby:
- Risk of lacerations (about 2%)
- Increased incidence of transient tachypnoea of the newborn
Is it possible to have a vaginal birth after caesarean section (known as VBAC)? Discuss
Yes, provided cause of caesarean section unlikely to recur and that there are no contraindications e.g.:
- Previous uterine rupture
- Classical caesarean scar (a vertical incision)
- Other usual contraindications to vaginal delivery (e.g. placenta praevia)
Success rate ~75%
There are 4 degrees of perineal tear; describe each (including subdivisions of 3rd degree tears)
- First-degree – injury limited to the frenulum of the labia minora (where they meet posteriorly) and superficial skin
- Second-degree – including the perineal muscles, but not affecting the anal sphincter (or any injury extending beyond vaginal mucosa)
-
Third-degree – including the anal sphincter, but not affecting the rectal mucosa
- 3A: <50% EAS
- 3B: >50% EAS
- 3C: EAS & IAS
- Fourth-degree – including the rectal mucosa
What is a mediolateral episiotomy?
Why is it done?
Cut perineum 45 degrees diagonally from the opening of vagina downwards (aim is to avoid damaging anal sphincter) in anticipation of needing additional room for delivery of the baby (e.g. before forceps delivery). Suture after delivery
Where are the transducers for CTG placed and what does each measure?
Two transducers:
- One above fetal heart → monitors fetal heart rate using doppler ultrasound
- One near fundus of uterus → monitors uterine contractions using ultrasound to assess tension in uterine wall?? CHECK DOES IT USE ULTRASOUND???
When assessing uterine contractions on CTG, what should you be looking at?
-
Number of contractions in 10 minutes
- Too few → labour not progressing
- Too many → can mean uterine hyperstimulation
- How long do contractions last
Important to interpret the fetal HR in relation to contractions. Should also assess how strong contractions are using palpation.
What do we mean by baseline rate on CTG?
What is a reassuring baseline rate?
What is a non-reassuring baseline rate?
What is an abnormal baseline rate?
- The baseline rate= average heart rate of the fetus within a 10-minute window
- Reassuring: 110-160bpm
- Non-reassuring: 100-109 or 161-180
- Abnormal: <100 or >180
**NOTE: 1 large square is 1 minute
What do we mean by variability on CTG?
What is a reassuring variability?
What is a non-reassuring variability?
What is an abnormal variability?
- Variation of fetal heart rate around the baseline
- Reassuring: 5-25bpm
- Non-reassuring:
- <5bpm for 30-50 minutes
- >25bpm for 15-25 minutes
- Abnormal:
- <5 for >50 minutes
- >225 for >25 minutes
Summary of baseline rate & variability from ZtoF
For early decelerations, discuss:
- What they are
- Cause
- What lowest point of deceleration corresponds to
- Whether they are normal or pathological
- Early decelerations start when the uterine contraction begins and recover when uterine contraction stops
- Caused by uterus compressing fetal head, raising ICP, stimulating vagus nerve
- Lowest point corresponds to peak of contraction
- Normal/physiological
For late decelerations, discuss:
- What they are
- Cause
- Whether they are normal or pathological
- Late decelerations begin at the peak of the uterine contraction and recover after the contraction ends
- Indicates insufficient blood flow to the placenta hence blood flow to fetus is significantly reduced causing fetal hypoxia an and acidosis. Insufficient flow may be due to maternal hypotension, pre-eclampsia or uterine hyperstimulation
- Pathological
For variable decelerations, discuss:
- What they are
- When lowest point of deceleration occurs
- How long the deceleration lasts
- Cause
- What are shoulders?
- Rapid fall of >15bpm fetal heart rate from the baseline with a variable recovery phase. They are variable in their duration and may not have any relationship to uterine contractions.
- Lowest point of deceleration occurs within 30 seconds
- Last <2 mins in total
- Often indicate intermittent compression of umbilical cord
- Shoulders are brief accelerations before and after deceleration and are reassuring sign that fetus is coping and adapting to blood flow
State what decelerations would be classed as non-reassuring
- Prolonged deceleration between 2-3 minutes
State which decelerations would be classed as abnormal
Summary of reassuring CTG from Geeky Medics
Summary of non-reassuring CTG from Geeky Medics
Summary of abnormal CTG from Geeky Medics
