Obstetrics Flashcards
Why is foetal monitoring important?
Identify a baby at risk of dying in utero
How might you monitor a foetus?
Pinard stethoscope
Hand held doppler - intermittent auscultation for low risk mothers
Cardiotocography for high risk mothers - continuous - measures FHR and uterine contractions
What might you see on abnormal CTG?
FHR variability
Accelerations/decelerations - early/variable/late
How can you get the true beat-to-beat FHR? When can you obtain it?
Fetal ECG
Only in labour (is invasive) when cervix is >2cm dilated
A fetal magneto cardiogram is a non invasive high resolution device that can accurately analyse the foetal heart. Problems with it?
Expensive and big
Shield environment
Skilled technician
Analgesia used in labour?
Simple - paracetamol/codeine
Opioids (IM/IV morphine, diamorphine, pethidine)
Entonox - half O2 and N2O
Epidural
Where an epidural be administered?
L3/4 space - Tuffier’s line at level of iliac crest
Epidural space - between dura and vertebral body
When to administer epidural? When not to (C/I)
Maternal request
maternal disease
Augmented labour - multiple births, induced, instrumental/operative labour likely
Not: maternal refusal, allergy, local infection
Why is epidural good?
Superior analgesia, maternal satisfaction
What sort of anaesthesia might you use for a caesarean section?
Spinal or general but prefer spinal
When might you administer GA for C section?
Imminent threat to mother/foetus
C/I to regional
Maternal preference
A 28 year old lady is 27 weeks pregnant (24+) presents with vaginal bleeding. What is this referred to as? What might cause it?
Antepartum haemorrhage - bleeding from genital tract after 24 weeks pregnancy, prior to delivery of fetus
Placental abruption, placenta praevi
Ectropion of cervix (trauma to cervical columnar cells causes bleeding)
A 30 year old is 32 weeks pregnant and has a 3 week hx of intermitant painless bleeds, which have become more frequent and heavier over time. Examination is normal apart from that the foetus lying transverse(/breech). Likely dx? Cause?
Placenta praevi - placenta implanted in lower segment of uterus - can be in lower segment (types I-II) or partially (III) or completely covering os (IV).
Aetiology unknown - twins, previous hx, C-section scar
Thought that in early pregnancy the upper part of uterus grows faster. Usually a praevi corrects itself - lower segment grows and placenta ‘moves upwards’
Complications of praevi?
Low lying placenta obstructs engagement of head
Placenta accrete - placenta implants into deeper endometrium/myometrium eg previous C section scar
Placenta percreta - placenta penetrates through uterine wall into surrounding abdominal structures eg bladder
Ix of suspected praevi?
NEVER DO VAGINAL EXAM - can provoke massive bleeding
USS - if <2cm from os after 32 weeks - like to be praevi at term
3D doppler USS to determine if accreta
Assess fetal/maternal well-being - CTG/FBC/clotting
Management of praevi?
Anti-D of Rh -ve
IV access, cross match
Nurse in left lateral position
If asymptomatic - delay birth til 37 weeks
If <34wks - steroids
Elective C section at 37-38 weeks by most senior person (Lower segment - LSCS) - if grade III/IV. Vaginal delivery if grade I
Prepare for haemorrhage - compression w/ Rusch balloon or hysterectomy
A 35 week pregnant lady has a 1 day hx of painful bleeding. O/E she is tachycardic, hypotensive, and has a tender, tense, woody hard uterus. Fetal heart beat seems abnormal. Lie is normal.
Placental abruption - part/all of placenta separates before the delivery of foetus Causes: autoimmune disease IUGR Pre-eclampsia - proteinuric hypertension Multiparity maternal trauma, smoking/cocaine use hx of abruptions Bleeding due to separation. Pain due to uterine contractions
Investigations of placental abruption?
CTG - establish fetal wellbeing (decelerations)
USS - r/o praevi
Bloods: FBC, U&E, coagulation, cross match
Rx of placental abruption?
Assessment/resuscitation: IV fluids
Nurse in left lateral position
Steroids (<34 wks)
Blood transfusion
Opiate analgesia
Anti-D if Rh -ve
Delivery: Emergency C section if fetal ditress
Labour w/ amniotomy if no fetal ditress and gestation >37wks
If <37 weeks and no distress - D/C but now high risk
Apart from praevia and abrption, name some others causes of antepartum haemorrhage
Undermined origin
Uterine rupture - sudden stop in contraction and fetal distress
Vasa praevi - fetal blood vessels run in membrane infront of presenting part - fetal distress - brisk painless bleeding at ROM
Gynae (cervical carcinoma/polyps)
Define a post partum haemorrhage
> 500mL blood loss <24h after delivery
or 1000mL after C section
Describe the causes of PPH
Tone - uterine atony in prolonged labour or retained placenta
Trauma - injury to birth canal eg w/ instrumental delivery - vaginal tear/cervical tear
Tissue - retained placenta/fetus - partial separation - blood accumulates in uterus
Thrombin - rare coagulopathy or consumption coagulopathy - DIC/shock as coagualtio factors used up in labour
RF: large baby, rapid progression, oxytocin can increase BP
How can PPH be prevented?
Use of oxytocin in 3rd stage of labour
Management of PPH?
IV access
Nurse flat
Remove placenta if bleeding or not expelled after 60mins
Uterine cause - IV oxytocin to contract uterus
Uterine atony - prostaglandin F2a into myometrium
Examine uterine cavity for retained fragments/cervix/vagina for tears
Surgery - Rusch balloon if bleeding from placental bed
Uterine artery embolization, hystrerectomy as last resort, brace suture
What is secondary PPH? How might it present?
Excessive blood loss between 24h and 6 weeks after delivery.
Tender uterus, os open
Causes of secondary PPH?
Endometritis, gynae pathology, gestational trophoblastic disease
Dx and Rx of secondary PPH?
Vaginal swabs, FBC, USS, biopsy and histology - r/o gestational trophoblastic disease
Abx
If heavy bleeding - ERPC
What are the cardiovascular changes in pregnancy?
Increase in plasma vol, CO, stroke vol, heart rate
Decrease in serum albumin con/colloid oncotic P
Venous return interfered with -> ankle oedema, varicose veins
Increase in coagulation factors and fibrinogen
Compression of inferior vena cava by uterus (aorto-caval compression) –> supine hypotension
What are the GI cahnages in pregnancy?
Biochemical:
N&V
Delayed gastric emptying
Prolonged small bowel transit time
GORD
Biochem: Ca requirement increase - transported to placenta. Serum Ca & phosphate fall, gut absorption increases (increased 1,25-DiOH vit D
Renal change in pregnancy?
Increase renal blood flow
Increased GFR
Salt & water reabsorption reabsorption increased by elevated sex steroid hormones
Urinary protein loss
Hepatic changes in pregnancy?
changes in oxidative liver enzymes eg cytochrome P450
Normal hepatic flow
ALP rises, albumin falls
Pulmonary changes in pregnancy?
Increase in tidal vol and minute ventilation
What does hCG do? What secretes
Signals presence of blastocyst and prevents breakdown of corpus luteum - synthesises progestins until placeta forms
Trophoblast cells of blastocyst secretes around day 6-7
Significance of progestins?
Myometrial quiescence - prevents contracting too early
Prepares uterus for implantation
(mifepristone will terminate)
Placenta continues to produce progesterones until baby delivered
Significant of oestrogens?
Change in cardiovascular system
fetal wellbeing
Increase breast growth
Pituitary to secrete prolactin
Hormones in milk production?
Prolactin - production
Oxytocin - ejection
Why is the fetus not rejected?
Extra-villus trophoblast has modified self-non self markers - HLA-G/E
Synctiotrophoblast unlikely to stimulate maternal response
What is the window of implantation?
Day 20-24 in cycle
What does the placenta form after implantation? What facilitates it?
Floating and anchoring villi
By fetal cytotrophoblasts in hypoxic conditions
Describe the uteroplacental circulation. Failure of spiral arteries causes?
Spiral arteries supply placental bed - become tortuous, dilated and les elastic by trophoblast invasion - failure causes pre-eclampsia, IUGR
Maternal blood through intervillous space
Fetal blood –> chorionic plate –> basal plate –> uterine vein
Describe fetoplacental circualtion
1 umbilical vein from placenta –> IVC in fetus and circulated and 2 umbilical arteries carry deoxygenatwed blood from fetus to placenta
Matrnal and fetal blood streams flow side by side in opposite directions
What is the function of the placenta?
Anchor fetus
Gaseous and nutrient exchange
Endocrine organ - hCG, oestrogens and progesterone
Barrier of infection of blood bourne diseases but syphilis, parvovirus, hep B/c, cytomegalovirus cross and infect fetus
Significance of progesterone
Decrease smooth muscle contractility
Raise body temp
Skin changes in pregnancy?
Linea nigra
Striae
Chloasma - brown pigmentation of skin
Palmar erythema
What is in stage 1 of labour?
From onset to full cervical dilation
Latent phase - 0-3cm
Active phase - 3-10cm, 1cm/hr
Possible interventions at stage 1 of labour?
Membrane sweep
Prostaglandin pessary
Oxytocin
What is engagement?
When head accommodates 2 fingers (2/5) above pubic symphysis
What are the mechanical factors of labour?
The power - uterine contraction - pulls cervix up (effacement)
The pelvis/planes (11x11cm)
The passenger - oblong head w/ bones not fused - fontanelles and sutures
What is attitude?
Degree of flexion if head - ideal is maximal flexion
What is presentation?
Part of foetus that occupies lower segment ie cephalic/breech
What is presenting part?
Lowest part of fetus palpable on vaginal exam (cephalic = vertex) but smaller degree of flexion –> face/brow
How is the fetus positioned usually? How might it be and what would this mean?
Occiput-anterior (face down)
Could be occiput-posterior - difficulty
Occipito-transverse - non rotation and needs assistance
Describe what marks the initiating of labour
Involunatry contractions of uterine smooth muscle in 3rd trimester - Braxton Hick contractiosn
Fetal prostaglandin production and oxytocin release
Labour = painful regular contractions - effacement/dilatation of cervix & shortening
Show- shedding of mucous plug
Rupture of membranes
What is cervical ripening/effacement?
When normal tubular cervix drawn up into lower segment until it is flat
Accompanied by show - mucus plug and release of membranes
How does the fetus and hormones stimulate a positive feedback throughout labour?
Fetus pushes down –> pressure on cervix
Prostaglandin released as muscles stretched –> release of oxytocin
Elevates Ca conc –> higher contractility
Describe the 2nd stage of labour
From full dilation to delivery of fetus
1 hr
Passive stage: full dilation until head reaches pelvic floor
Active stage: mother pushing, bearing down
Why might the second stage of labour be delayed?
Brow/face/shoulder presentation
Transverse/OP/OT position
Describe 3rd stage of labour
From deliver of foetus to delivery of placenta & membranes
Active - oxytocin, cord clamping after 1 minute, cord traction
Physiological - clamp cord after pulsations stops
Uterine muscles contract and compress blood vessels
Blood loss <500mL
Prolonged if >30 mins active, >60 mins physiological
How is the progress of labour monitored?
FHR monitored every 15 mins or continuous by CTG
Contractiosn assessed every 30mins
Partogram - dilation of cervix, descent of head
Laert/action lines - indicates slow progress
Maternal pulse rate assessed every 60 min
Maternal BP & temp checked 4hourly
VE (vaginal exam) offered every 4 hours
offered
Urine checked for ketones & protein every 4 hours
Common causes of failure to progress?
Insufficient uterine action
Hyperactive uterine action - excessively strong contractions
Inefficient uterine action in nulliparous women
Malpresentation
Small pelvis
Rx of Insufficent uterine power?
Augmentation - amniotomy then oxytocin