Week 4 Flashcards
External obliques - attachments
What direction do the fibres of these muscles run in?
Attaches to the lower ribs (7-11, sometimes 12), pubic tubercle and linea alba
fibres run in the same line as the external intercostals, “hands in pockets”
Internal obliques - attachments
What direction do the fibres of these muscles run in?
Attachments - lower ribs, thoracolumbar fascia, iliac crest and linea alba
Fibres run in the same direction as the internal intercostals, “hands on chest”
Where does the linea alba run between?
From the xiphoid sternum to the pubic symphisis
Describe the rectus sheath. How does it differ…
- above the arcuate line
- below the arcuate line?
Why does this change occur?
The rectus sheath is immediately deep to the superficial fascia and is a combined aponeuroses of the anterolateral abdominal wall muscles (external ob., internal ob., and transv. abdo.)
- Above the arcuate line, the rectus sheath is split into anterior and posterior leaflets. The anterior leaflet is made up of the external oblique aponeurosis and the anterior portion of the internal oblique aponeurosis. The posterio leaflet is made up of the posterior part of the internal oblique aponeurosis and the transverse abdominis.
- Below the arcuate line, the rectus sheath is all anterior
This change occurs because abdominal organs sit lower in the body due to gravity - having all components of the sheath anteriorly provides more protection for the muscles
The spermatic cord in the male and the round ligament of the uterus in the female pass through which layer of the rectus sheath?
What does this layer become incorporated into in the male?
The spermatic cord and the round ligament pass through the transversalis fascia at the entrance to the deep inguinal ring
In the male, the transversalis fascia extends downwards as the internal spermatic fascia
What nerves supply the anterolateral abdominal wall? From what direction do they enter?
Nerves enter from the lateral direction
The 7th-11th intercostal nerves go on to become the thoracoabdominal nerves after they cross over the costal cartilage
Other nerves involved include subcostal (T12), iliohypogastric (L1) and ilioinguinal (L2)
Describe the arterial supply to the anterolateral abdominal wall
Superior epigastric artery (1.6mm)
- continuation of the internal thoracic arteries
- emerges at the superior aspect of the abdominal wall
- lies posterior to rectus abdominis
Inferior epigastric artery (3mm)
- branch of the external iliac artery
- emerges at the inferior aspect of the abdominal wall
- also lies posterior to rectus abdominis
What layers are passed through when performing a LSCS (lower segment caesarean section) incision?
What other procedure should be performed to make this incision easier?
Skin and fascia
(anterior) rectus sheath as below the arcuate line
Separation laterally of the rectus abdominis muscles
Transversalis fascia and peritoneum
Retract the bladder (urinary catheterisation can be performed to aid this)
Uterine wall
Amniotic sac
What layers are passed through when performing a laparotomy?
These procedures are relatively bloody/bloodless. What does this mean clinically?
Skin and fascia
Line alba
Peritoneum
Relatively bloodless, which means that the wound may be harder to heal and there is an increased risk of wound herniation/dehiscence
When performing laparoscopy and using lateral ports, what vessel must care be taken to avoid?
What landmarks can be used?
When performing lateral ports, care must be taken to avoid the inferior epigastric artery
The IEA emerges just medially to the deep inguinal ring. Hesselbach’s Triangle can be used to help avoid hitting IEA (rectus abdominis medially, inguinal ligament inferiorlaterally and IEA superolaterally)
When performing a hysterectomy, what structures must be carefully avoided? How can this be done?
The ureters should be avoided - they will vermiculate when touched, while uterine arteries will appear pulsatile. Can also use the memory aid “water under the bridge” as the ureter passes inferiorly to the artery and vein
Where might a woman give birth?
Which is most common?
Consultant-led unit
Midwife-led unit
Homebirth
96% of women in the UK still give birth within a hospital setting
Describe Ferguson’s Reflex
Stretching of the cervix causes the release of oxytocin, which stimulates uterine contractions and thus further pressure on the cervix causing more release of oxytocin. POSITIVE FEEDBACK MECHANISM
What do the following hormones do with regards to the onset of labour?
- Progesterone
- Oestrogen
- Oxytocin
Progesterone - keeps the uterus ‘settled’, prevents the formation of gap junctions and hinders the contractibility of myocytes
Oestrogen - makes the uterus contract and promotes prostaglandin production
Oxytocin - initiates and sustains contractions and acts on the uterus lining (decidual tissue) to promote prostaglandin release. Near the end of pregnancy, the number of oxytocin receptors found in myometrial and decidual tissues increases
‘Rupture of membranes’ refers to what? When might this occur?
Refers to rupture of the liquor - fluid that nurtures and protects the foetus and facilitates movement
Timing may be…
- pre-term
- pre-labour
- first stage
- second stage
- “born in a caul”
What cervical changes occur during labour?
Cervix softens through various methods…
- increase in hyaluronic acid leads to an increase in the number of molecules among collagen fibres
- decrease in bridging among collagen fibres = decrease in firmness
- cervical ripening (decrease in fibre collagen alignment and strength, and decrease in tensile strength of the cervix matrix)
What is Bishop’s score used for? What is it made up of?
Pre-labour scoring system used to determine whether or not labour needs to be induced.
Made up of 5 elements…
- Position
- Consistency
- Effacement
- Dilatation
- Station of the pelvis
The higher the score, the more likely induction will be needed
Name the various stages of labour and what each comprises of
First stage (Latent Phase, 3-4cm dilatation, and Active Phase, full dilatation a.k.a. 4-10cm)
Second stage - delivery of baby
Third stage - expulsion of placenta and membranes
Describe the features of the First Stage of labour
Latent Phase
- mild irregular uterine contractions
- cervix shortens and softens
- duration is variable (may last a few days!)
Active Phase
- slow descent of the presenting part
- contractions progressively become more rhythmic and stronger
- analgesia, mobility and parity of the mother increase the variability of this stage
Describe the features of the Second Stage of labour
Spans from complete dilatation of the cervix to delivery of the baby
Nulliparous women
- considered prolonged if exceeding 3 hours (if regional analgesia)
- or considered prolonged if 2 hours with no analgesia
Multiparous women
- considered prolonged if exceeding 2 hours w/ regional analgesia
- or 1 hour with no analgesia
Describe the features of the Third Stage of labour
Describe the difference between expectant and active management at this stage
At what point would removal under GA be considered?
Spans from delivery of the baby to expulsion of the placenta and membranes
Average duration is 10 minutes, however can last 3 hours or longer
expectant management - spontaneous delivery of the placenta
active management - use of oxytocic drugs and controlled cord traction (lowers risk of PPH)
After 1 hour, preparations are made to remove the tissue under general anaesthetic
Explain Braxton Hicks contractions and how they differ from normal contractions.
How does having had previous children affect this phenomenon?
A.k.a. “false labour”
Tightening of the uterine muscles, thought to be in preparation for actual labour
Can start as little as 6 weeks into pregnancy, but typically occur in the 3rd trimester.
Unlike normal contraction, BH contractions are irregular and do not increase in frequency or intensity
BH contractions typically resolve with ambulation/change in activity
Previous pregnancies increase the likelihood of BH contractions due to increased uterus excitability
How can you tell if contractions are “true” and signalling real labour?
How are true contractions brought about?
Timing of the contractions become more evenly spaced and the time between them becomes shorter and shorter
The duration of each contraction also increases, and will also become more painful and intense over time
Oxytocin stimulates the uterus to contract by tightening the top of the uterus and pushing the baby inferiorly into the birth canal. This also usually promotes thinning of the uterus
Three key factors are in interplay between one another during labour, these being Power, Passenger and Passage.
Describe Power
= uterine contraction
The uterus is made up of smooth muscle and connective tissue, with a pacemaker region in the tubal ostia that causes waves to spread downwards. The waves generated from each ostia synchronise with each other
As the upper segment contracts and retracts, the lower segment and cervix relax and stretch
Normal contractions have fundal dominance
Frequency of contractions - 3-4 every 10 mins
Duration - 10-15 seconds, going up to 45 seconds
Three key factors are in interplay between one another during labour, these being Power, Passenger and Passage.
Describe Passage
What are the different types of pelvis? Which is preferred for childbirth?
= journey of the baby through the pelvis
Gynaecoid - most suitable for childbirth
Anthropoid - large oval-shaped inlet w/ large anterio-posterior diameter, but smaller transverse diameter
Android - heart-shaped inlet and narrower from the front. Afro-caribbean women more at risk
Platypelloid
Three key factors are in interplay between one another during labour, these being Power, Passenger and Passage.
Describe Passenger (specifically position)
= baby
Normal position
- longitudinal lie
- cephalic presentation
- vertex is the presenting part
- position is occipito-anterior
- head is flexed
Abnormal position
- presentation - breech, oblique, transverse lie
- position - occipito-posterior
How can foetal position be determined during vaginal examination?
Palpation of the fontanelles
Anterior fontanelle has 4 points (diamond)
Posterior fontanelle has 3 points (triangle)
What analgesia options are available during labour?
Entonox (gas and air) - best option, doesn’t affect the baby and the mother can still push
Paracetamol/co-codamol
Diamorphine (standard for the first stage of labour)
Epidural (useful for induced labour which is typically more painful)
Remifentanyl - not used much any more as it can cause respiratory depression
TENS (transcutaneous electrical nerve stimulation)
What are the 7 cardinal movements of labour?
- engagement (described in 5ths relating to foetal head in pelvis)
- descent (foetal head in occiput transverse position)
- flexion (allows smallest diameter of foetal head to pass first)
- internal rotation
- crowning and extension
- restitution (head returning to the correct anatomical position in relation to the shoulder) and external rotation
- expulsion, anterior shoulder first
Describe foetal crowning
Appearance of a large segment of the foetal head at the introitus
Labia are stretched to full capacity, with largest diameter of foetal head being encircled by the vulval ring
Care of the perineum at this stage is vital to reduce trauma. Deliverer’s hands should guide, but not lead, to minimise risk of tearing
Episiostomy may be required to preserve tissues
Following delivery, when should the foetal cord be clamped?
Should be delayed to up to 3 minutes after delivery/cessation of pulsations of cord
This is because immediate clamping has been associated with both short and long-term neonatal problems due to reducing the amount of RBCs to the baby by more than 50%
What classic signs during the Third Stage indicate separation and expulsion of the placenta?
Uterine contractions, hardening and rising
Permanent lengthening of the umbilical cord
Variable amounts of blood gushing
Appearance of the placenta and membranes at the introitus
Expulsion usually occurs 5-10 minutes after delivery, and is considered normal up to 30 minutes
What active management steps may be made during the Third Stage?
Prophylactic administration of synometerine (1ml ampoule containing 500 micrograms ergometrine maleate and 5 IU oxytocin or oxytocin (10 units)
Cord clamping and cutting
Controlled cord traction
Bladder emptying
What is considered to be a normal and abnormal amount of blood loss during labour?
Normal - volume up to 500mls
Abnormal - greater than 500mls, more significance if greater than 1000mls
Any blood loss in labour prior to delivery, apart from “show” is considered abnormal and requires consultant referral
How is haemostasis during labour achieved?
Tonic contractions - uterine muscle ‘lattice arrangement’ strangulates blood vessels
Thrombosis of torn vessel ends - pregnancy is a hypercoagulable state
What is puerperium? What occurs during this stage?
Period of repair and recovery following birth, lasting approx 6 weeks
Vaginal discharge of varying colours over the next few days
Uterus involutes and weight reduces from 1000gms to 50-100gms
Endometrium regenerates after 1 week
Regression, but never back to pre-pregnancy state
How is lactation initiated?
Placental expulsion and a decrease in progesterone and oestrogen (previously blocked prolactin during pregnancy)
What is the normal size of an adult male testis? Name some conditions that may affect this volume
Normal size - 12-15mls
Conditions: cryptoorchidism (undescended testis), Klinefelters, hypogonadism (primary, testicular torsion, infection, anabolic steroid use), varicocele
How do sympathetic and parasympathetic innervation affect erection?
Parasympathetic - vasodilation of the arteries running through the penis, Buck’s fascia surrounding the penis maintains the pressure resulting in compression of the penile veins and maintenance of erection
Sympathetic - vasoconstriction of the arteries running through the penis, reducing blood flow and pressure and allowing blood to flow back through the penile veins
What are the functions of the following tissues?
- Epididymis and vas deferens
- Seminal vesicles
- Prostate gland
- Bulbourethral gland
Epididymis and vas deferens - exit route from the testes to the urethra, site of concentration and storage of sperm, site of sperm maturation
Seminal vesicles - produce semen into ejaculatory duct, supply fructose, secretion of prostaglandins and fibrinogen
Prostate gland - produces alkali fluid and clotting enzymes to cause clotting of sperm in the female reproductive tract
Bulbourethral gland - secretes mucous to act as lubricant
Describe the changes in surface anatomy of the uterus during pregnancy
Height of the fundus goes up and out
At 20 weeks, approximately at the height of the umbilicus
At 36 weeks, approximately the height of the xiphoid process
At term, the height goes down slightly as the baby’s head engages with the pelvis
(approximately 1cm of fundus height per week of pregnancy)
What are some of the main medical problems seen in pregnancy?
Hypertension
Diabetes
Venous thromboembolism VTE
Cardiac disease
Respiratory disease - asthma
Connective tissue disease - APS
Epilepsy
Obesity
How do the following change in pregnancy?
- total blood volume
- heart rate
- stroke volume
- cardiac output
- peripheral vascular resistance
All increase, except PVR which decreases by 15-20%
What kind of heart disease issues may be exacerbated during pregnancy?
Pulmonary hypertension (including Eisenmonger’s, a chronic left-to-right cardiac shunt due to a congenital abnormality that has a 30-60% risk of mortality during pregnancy)
Congenital heart disease
Acquired heart disease
Cardiomyopathy
Artificial heart valves
Ischaemic heart disease
Arrhythmias
What is NYHA classification used for?
Used as a functional assessment of impact of heart disease on function
Class I - no limitation to normal physical activity
Class II - mild symptoms only in normal activity
Class III - marked symptoms during normal activity
Class IV - severe limitations, symptomatic at rest
What cardiac symptoms are common in pregnancy?
Which cardiac complications may prove to be fatal during pregnancy?
Common symptoms - palpitations, extra-systoles and systolic murmurs. These are usually benign
Pulmonary hypertension and fixed pulmonary vascular resistance often result in fatality
What investigations would you perform for the following…
- Ectopic beats
- Sinus tachycardia
- SVT
- Hyperthyroidism
Ectopic beats - ECG
Sinus tach. - ECG, FBC, Thyroid function testing, echocardiography
SVT - ECG/24hr ECG, thyroid function, echo
Hyperthyroidism - thyroid function, ECG
How is lung function affected in pregnancy?
O2 consumption increases
Metabolic rate increases
Tidal volume increases
Resp rate remains unchanged
Functional residual capacity decreases
PaO2 increases, PaCO2 decreases, arterial pH increases
Breathlessness is common in pregnancy, especially in the third trimester, and is seen at rest/when talking but improves with exertion
What is the most common medical disorder to complicate pregnancy? How often is it recognised? How does pregnancy affect this condition?
Asthma, affects approx 7% of women childbearing age
Often undiagnosed and untreated at time of pregnancy
10% will have an acute exacerbation during pregnancy
Rule of 3rds - 1/3 will get better, 1/3 remain unchanged, and 1/3 will get worse
However, if well-controlled, asthma does not affect pregnancy outcomes. Poorly controlled asthma is a greater risk to pregnancy than the treatment used to manage it
How should women with asthma be managed during labour?
Aim for vaginal delivery
Acute attack unlikely due to the production of endogenous steroids
Women shouldn’t discontinue use of inhalers during labour, inhaled beta-2 agonists don’t affect uterine contractility or onset of labour
If taking oral steroids, give the woman IV hydrocortisone
What is the biggest direct cause of maternal mortality? How does likelihood change during pregnancy?
How does this most commonly present?
VTE - 4-6x increase during pregnancy
85-90% of DVTs occur in the left leg, and more than 70% are in the ileofemoral region
What are the components of Virchow’s Triad and how does pregnancy affect these components to increase the likelihood of VTE development?
Components - hypercoaguability, venous stasis, vascular damage
Both hypercoaguability and venous stasis increase in pregnancy
Vascular damage may occur at birth, and is more likely to occur with forceps delivery
How is pre-eclampsia caused?
Diffuse vascular endothelial dysfunction causing widespread circulatory disturbance, with no definitive cause identified however it is likely to be due to a number of factors, including…
- abnormal formation and development of the placenta
- immunological factors
- pre-existing maternal pathology e.g. hypertension, obesity, APS etc.
- dietary and environmental factors
- poor trophoblastic invasion results in poor placental perfusion, causing an increase in maternal blood flow and oxidative stress, hypoxia and the release of factors that promote endothelial dysfunction, inflammation etc.
- results affect the brain, liver, kidneys, RBC formation etc.
Early/Late decelerations on a CTG are considered abnormal. Which of these could indicate hypoxia of the foetus?
Late decelerations are abnormal, while early decelerations are physiologically normal
Both could indicate hypoxia of the foetus - in a normal contraction, oxygen to the foetus is impaired due to squeezing of the baby’s head.
