Chapter: Medicine Study Notes : Reproductive and Obstetrics


Regular contractions (usually 3 in 10 minutes, lasting 40 – 50 seconds)



·        Definition:

o   Regular contractions (usually 3 in 10 minutes, lasting 40 – 50 seconds)

o   Cervical change:

§  More anterior

§  Effaced: depth of „rim‟ normally 2 cm, 50% effaced = 1 cm

§  Dilated

§  Soft (hard = like forehead, normal = like nose, soft = like chin)

o   +/- Show (mucus plug) or ROM (rupture of membranes)

·        80% of all pregnancies last 38 - 42 weeks. 10% are preterm. 10% beyond the start of the 43rd week (although biggest cause is inability to reliably date conception)

·        How does it start: 

o   Uterus: ­distension, ­gap junctions in smooth muscle, ­oxytocin receptors

o   Cervical ripening: PGE breaks down collagen + effect of Braxton-Hicks contractions

o   Fetus: ?vasopressin released in response to transient hypoxia, ?other hormones

·        Examination: 

o   Mother: monitor BP (hypo ® ?blood loss, hyper ® ?pre-eclampsia), pulse, temperature (eg infection if prolonged period post-rupture) 

o   Foetal position: by abdominal inspection and palpation. 2/3rds of babies head first with back on the left. Descent – what portion of the head is below the pelvis (eg 3/5ths) 

o   Fundal height

o   Foetal welfare: 

§  CTG for 20 minutes (but incidence of fetal distress in early labour is low. Continuous monitoring ® ­interventions) 

§  Intermittent auscultation every 15 – 30 minutes following a contraction. Approx every 5 minutes in 2nd stage. 

·        Fetal position – Definitions:

o   Lightening: 

§  = Baby dropping. ® ¯SFH, development of lower segment of the uterus, descent of fetal head into pelvis 

§  1st pregnancy: 2 – 3 weeks before

§  2nd pregnancy: may not be till 2nd stage of labour – uterus has lost some of its tone – doesn‟t push baby down so well 

o   Fetal lie: relation of fetal spine to mother‟s spine. Longitudinal (cephalic or breech), transverse, oblique (unstable lie)

o   Fetal presentation: portion of the fetus in the birth canal:

§  Cephalic (96%): vertex, sinceput, brow, face

§  Breech (3%): Frank (extended – „foot in mouth‟), Complete (knees and hips flexed),

§  Incomplete (footling).  Only worry after 36 weeks – it can turn fairly easily before then

§  Transverse or oblique  (1%)

o   Fetal Attitude: “posture” of the fetus, eg extended neck 

o   Fetal Position: Relation of occiput (vertex) to the maternal pelvis. Left or Right, Anterior, Posterior, or Transverse, eg

§  LOA = left occiput anterior (face down, 8 o‟clock) – most common position

§  LOT = left occiput transverse

§  OA = occiput anterior (6 o‟clock)

·            LOP = left occiput posterior (face up)

 ·       Sutures:


o  Caput succedaneum: swelling of the fetal scalp immediately over the os 

o  Moulding: Overlapping cranial bones in cephalic presentation. May ¯BPD (biparietal parameter) by 0.5 – 1.0 cm 

o  Crowning: encirclement of largest diameter of the fetal head by the vulvar ring

·        Adequate sized pelvis has:

o  Wide pubic angle (skeleton can fit a fist)

o  > 10 cm between ischial spines

o  Can‟t reach sacral prominence (top of sacrum) on vaginal exam

·        Delivery of the baby: 

o  Engagement: time when BPD passes through the pelvic inlet. Abdominal, 2/5 is palpable. If engaged, you know the pelvic inlet is big enough

o  Descent: Extension of fetal body.

o  Flexion of neck 

o  Internal rotation. Head rotates from 8 o‟clock to 6 o‟clock. Usually descent through pelvis transverse, then need to rotate face downwards

o  Extension: once head reaches vulva, occiput in direct contact with symphasis.  Ritgen Manoeuvre        upward pressure on chin through perineum from below, downward pressure on occiput (stop anterior tear) 

o  External Rotation/Restitution – occiput goes back to original position (transverse) – now realigned again with shoulder. Check for nuchal cord (around neck), clear nasopharynx 

o  Expulsion: anterior shoulder, followed by posterior shoulder. Clamp and cut cord, with baby below the level of the placenta if possible or if prem

o  Episiotomy: NOT routine. In NZ do them medio-lateral at time of Crowning. 1st degree = superficial, 4th degree = deep, including rectal sphincter and mucosa

·        Stages of labour: 

o   Stage 1: Cervical effacement and dilation - Friedman phase – plot on a partogram: · Latent phase (cervical softening). 20 hours in nullip, 14 hours in multip

·        Active Phase: Acceleration phase and deceleration phase (= transition). Cervix dilates 1.0 – 1.2 cm/hr (Primiparous), 1.5 cm/hour (multiparous) to a maximum of 10cm dilated 

o  Stage 2: begins at 10 cm dilated and ends with delivery of the baby.  2 hours in primip, 45 minute        1 hour in multip. 

o  Stage 3: separation and expulsion of the placenta · Active management of 3rd stage

·        Especially if risk of PPH (big baby/twins/previous PPH/anything that makes the uterus big eg polyhydramnios). 

·        Give 5 – 10 units Syntocinon (IV if risk of PPH, IM otherwise) when shoulder delivers

·        Can use syntometrin (oxytocin + a little ergometrine – contraindicated if hypotension)

·        If PPH then IV infusion following bolus (T½ of Syntocinon is 3 – 5 minutes) 

·         Complications of Syntocinon: hyperstimulation (® ­fetal hypoxia), uterine rupture, water intoxication (Syntocinon is like ADH), uterine muscle fatigue (® post-delivery uterine

§  atony ® ­risk of PPH)

§  Signs of placental separation: sudden rush of blood, uterus rises, cord lengthens 

§  OK to wait if no heavy bleeding. Gentle traction on chord with supra-pubic pressure (stops uterus coming down) or fundal massage and maternal bearing down without traction 

§  Can manually deliver (place hand into uterus and separate) – if no haemorrhage then wait for anaesthesia

o  Then inspection, repair, rectal exam 

·        Cord prolapse: Cord comes through cervix before head. C-section usually indicated. In meantime try to control pressure on cord – don‟t push it back up. Risk if transverse lie 

·        Pain Relief:

o   Inhalation agent (eg nitrous oxide) 

o   Epidural: complications – hypotension, urinary retention, total spinal block, prolonged expulsive effort

o   TENS 

o   Narcotics eg pethidine: action lasts 3 hours and can cause fetal respiratory distress – don‟t give if delivery expected within 3 hours


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