Normal pregnancy and delivery

INTRODUCTION

• Failure rate of compliant COCP is <1/100 but nearly 30% are not consistently compliant
• Levonorgestrel implants 0.8/100 failure rate in first 5 years
• Partial salpingectomy 0.75/100 failure rate
• Gestation measured from day 1 of last normal menstrual period

PHYSIOLOGICAL CHANGES

CVS

• 40% increase in blood volume, 45% increase in cardiac output, 17% increase in resting heart rate
• 20% reduction in systemic vascular resistance
• BP nadirs in 2nd trimester (diastolic decrement 10-15mmHg and systolic decrement 5-10mmHg)
• Elevation of diaphragm displaces heart up and to the left with larger cardiac silhouette on CXR and slight left-axis deviation on

ECG

• Small benign pericardial effusion can exist

Respiratory

• Dyspnoea but no increase in RR
• 40% increase in tidal volume with normal PaCO2 of 30
• FRC reduced due to rise in diaphragm

GI

• Gastric reflux due to delayed gastric emptying, decreased intestinal motility, reduced lower oesophageal tone
• ALP rise (from placenta)
• Induction of hepatic enzymes
• Gallbladder emptying delayed and less efficient – increases risk of cholelithiasis
• Urinary system
• GFR rises by 50% in 2nd trimester with reduced urea and creatinine
• Physiological hydroureter/nephrosis (less so on left side due to sigmoid colon protecting ureter from uterus)

Haematopoietic

• 40-45% increase in blood volume due to rise in plasma and erythrocyte count
• Hb concentration drops (should still be >110) due to dilution
• Reticulocyte count increased during second half of pregnancy
• Leukocytes 5-12 normal
• In second trimester, leukocyte function is depressed with resultant increase in risk of infection
• Circulating coagulation factor concentrations and ESR rise
• Platelet count may decrease slightly due to increased consumption

Endocrine

• Hyperinsulinaemia and fasting hypoglycaemia
• Post-prandial hyperglycaemia
• Free thyroxine and TSH are unchanged in pregnancy

Uterus

• Enters abdominal cavity beyond 12 weeks
• Progressive increase in blood flow from 450mL/min to 650mL/min at term

Breasts

• Breast tenderness and tingling from first trimester
• Nipple size and pigmentation increase
• Enlarge and become more nodular

CLINICAL FEATURES

• Quickening noted at 18-20 weeks (primigravida) and 16-18 weeks (multigravida)
• Early pregnancy abdominal discomfort can be from any differential (non-pregnant and pregnant) + round ligament tension and pelvic congestion

Syncope

• DDx includes anaemia, electrolyte imbalance, dehydration, PE, arrhythmia but often no cause found
• Premature atrial and ventricular ectopics are increased in pregnancy
• 10% of episodes of near-syncope, palpitations, dizziness, syncope are actually due to arrhythmia

Examination

• Fetal heart sounds on Doppler from 8-10 weeks (16-18 weeks with foetal stethoscope)
• Normal HR 120-160/min
• At 12 weeks – Fundus at pubic symphysis
• At 16 weeks – Midway pubic symphysis to umbilicus
• At 20 weeks – Umbilicus + 1cm for each week

DIAGNOSIS

DDx of positive hCG

• Normal intrauterine pregnancy
• Recent pregnancy
• Ectopic pregnancy
• Molar pregnancy
• Serum beta-hCG – Detects levels as low as <5mIU/mL
• Urine beta-hCG – Detects levels as low as 10-20mIU/mL
• False negative rate of 1% as early as 1 week post-conception
• If urine is dilute, false negative may occur up to 50mIU/mL

Pelvic USS

• Earliest definitive diagnostic finding is gestational sac (TA-USS 5.5 to 6 weeks; TV-USS 4-5 weeks)
• Yolk sac (TVUSS 5-5.5 weeks)
• Fetal pole (TVUSS 5.5-6 weeks)
• Cardiac activity (TVUSS 6 weeks)
• HR <100 in early pregnancy
• HR 120-160 beyond 7 weeks

EMERGENCY DELIVERY

History

• Onset and frequency of contractions
• Fetal membrane status
• Presence or absence of vaginal bleeding
• Presence or absence of fetal movements
• G-P-
• History of precipitous deliveries
• Prenatal care
• EDD
• Dating
• Nagele rule (add 9 months and 7 days to first day of LNMP)
• Fundal height (umbilicus + 1cm per week

Initial assessment

• Maternal vital signs (particularly BP) and CTG
• Persistent FHR <110 is critical
• IV access x 2 large bore
• FBC, Chem20, Group and save, typing, antibodies and urinalysis
• False labor – Typically lower abdominal, irregular contractions that do no lead to cervical changes (Braxton-Hicks)
• True labor – Contractions regular, painful, start in fundus and radiate down and to back with cervical dilatation and effacement

Examination

• Fundal height, abdominal/uterine tenderness and fetal position/presentation
• If no PV bleeding – Sterile speculum
• If PV bleeding – Must identify position of placenta first before any speculum/bimanual
• If ROM suspected, sterile speculum without lubricant and no digital examination (increased risk of infection)
• Can confirm ROM (nitrazine, pooling, ferning), assess cervix, assess for umbilical cord or fetal parts, take swabs for GAS, C.trachomatis, N. gonorrhoea and assess for herpes vesicles (Contraindication to vaginal delivery)
• Avoid lubricant as can give false positive nitrazine test (unless ROM has been confirmed)
• Particularly important if preterm as digital examination can induce labor

Cervical exam

• Dilatation = diameter of internal os indicating progression of labor (10cm = full dilatation)
• Effacement  = Process of thinning described in terms of % cervical length
• Station = Level that fetus occupies in pelvis with reference point being ischial spines at 4 and 8 o’clock
  • Station negative if above these
  • Station 0 at ischial spines
  • Station +1, +2 or +3 (visible scalp at introitus) if below ischial spines

Malpresentation

• 15% at 32 weeks but only 4-7% at term
• Difficult via Leopold maneuvers if inexperienced but digital examination may identify cranial sutures, scalp or fetal limbs to help

Rupture of membranes

• Important in predicting pending labor as well as complications such as infection or cord prolapse
• PROM occurs in 8% of third-trimester pregnancies
• 50% of women with PROM deliver within 5 hours
• 95% of women with PROM deliver within 28 hours
• Screen for symptoms of infection
• If membranes are intact, do not perform amniotomy as may lead to precipitous delivery or cord prolapse
• Note meconium-stained liquor

PROM

• If <37 weeks = PPROM
• Prolonged rupture of membranes occurs if delivery does not take place within 18 hours of PROM
• PPROM is managed conservatively if <34 weeks
• Tocolytics reserved for maternal transport or for steroid therapy to take effect
• In PPROM, can prolong latency with 7 day course of amoxicillin and erythromycin

Fetal distress

• Late decels (persistent drop in FHR during contractions lasting >30 seconds after the contraction)
• Prolonged fetal bradycardia >5 minutes is an indication for Cat 1 Caesarean section
• Can try maternal repositioning to left lateral, right lateral and knee-chest position to remedy decels
• Maternal IV hydration + O2 can improve late decels
• Terbutaline injection can halt uterine contractions and increase blood flow to uterus
• Start IV hydration
• If fetal head visible during contractions and cervix is fully dilated and effaced, best to bring obstetrician to ED
• Important to ensure cervix is fully dilated before patient begins to push to avoid cervical lacertions
• Guide patient to push 3 times, each for 10 seconds, during contractions only
• Step
  • Fetal descent
  • Engagement
  • Flexion
  • Descent
  • Internal rotation
  • Extension
  • External rotation
• Can assist delivery by gentle digital traction on inferior perineum
• If episiotomy is clinically required (for fetal distress, shoulder dystocia or for operative vaginal delivery) infiltrate 10mL 1% lignocaine into posterior fourchet and make 2-3cm cut with scissors 45 degrees from midline posteriorly
• Can provide gentle counter-pressure as head extruded from introitus to prevent rapid expulsion and subsequent perineal tears
• As head delivers, check neck for cord (25-35% of term deliveries)
  • If loose, move over infant head
  • If tight, clamp at two sites and transect to allow delivery
• Deliver anterior shoulder through gentle downward pressure
• Then deliver posterior shoulder and then body in controlled manner
• Umbilical cord then double-clamped 3cm from insertion at umbilicus and transected with sterile scissors
• Delivery of placenta
  • Usually within 10-30 minutes
  • Gentle traction only
• Once placenta delivered, gentle fundal massage promotes contraction + Oxytocin 10IU IM +- infusion

COMPLICATIONS OF DELIVERY

Umbilical cord prolapse

• 0.4% of all deliveries
• Compression of cord can be life-threatening to fetus and need Cat 1 C/S
• If bimanual reveals palpable, pulsating cord, push fetal head off cord and transport to C/S
• Never try to reduce a prolapsed cord

Shoulder dystocia

• 1% of all vaginal deliveries
• Fetal respiratory distress due to impaired ventilation by thoracic compression and circulation compromise due to umbilical cord and fetal neck compression
• After head delivered, it retracts against perineum (turtle sign)
• Note time of recognition, position mother in extreme lithotomy position (legs sharply flexed against abdomen = McRoberts maneuver)
• Aim is delivery within 5 minutes
• Drain bladder if not done already
• Episiotomy only useful if narrow fourchet or to allow fetal manipulation
• Suprapubic pressure to disimpact anterior shoulder (NOT FUNDAL PRESSURE)
• Woods corkscrew maneuver
  • Grasp posterior scapula of infant with two fingers and rotate shoulder girdle 180 degrees to rotate posterior shoulder into anterior position and deliver that one
  • Try to deliver posterior shoulder by pass hand posteriorly in vagina, grasp elbow and flex, deliver arm then shoulder and anterior shoulder should follow

Breech presentation

• 3-4% of term pregnancies
• 25-30% of preterm deliveries
• Major concern is head entrapment
• Main recommendation is to keep hands off and allow delivery to happen spontaneously
• Allows presenting portion of fetus to maximally dilate the introitus
• Guidelines suggest not to touch anything until umbilicus delivered, then place fingers medial to each thigh pressing out laterally to deliver the legs
• Rotate fetus to sacrum anterior position
• Once scapulae appear, gently rotate until one humerus can be followed down, rotated across chest and delivered
• Then rotate and deliver other arm
• Then place index and middle fingers over maxillary bones to keep head flexed and mother then delivers head (with no traction)

Preterm delivery

• 12% incidence
• 21 weeks = 0% survival
• 25 weeks = 75% survival (neurological intact??)
• In general, if 18-22 weeks, perform initial resuscitative efforts until determination of viability is made

PRIMARY POST-PARTUM HAEMORRHAGE

Definition

• Excessive bleeding in first 24 hours post-birth
• >500mL post-vaginal birth or >1000mL post-C/S
• Severe >1L
• Very severe >2.5L

Aetiology

• Tone (70%)
• Trauma (20%)
• Tissue (10%)
• Thrombin (<1%)

Risk factors

Antenatal

• Increased maternal age 2.0
• Parity >3
• Previous PPH
• Prior uterine surgery
• Pre-eclampsia
• Anticoagulants
• Anaemia
• Multiple pregnancy
• Antepartum haemorrhage

Intrapartum

• Prolonged third stage >30 mins
• Retained placenta
• Macrosomia >5kg
• Instrumental vaginal birth
• Episiotomy
• Uterine rupture
• GA
• Temp >38 in labour

Estimation of blood loss

• 500-1000mL: Palpitations, dizziness, tachycardia
• 1000-1500mL: Slight decrease in SBP, weakness, sweating, tachycardia
• 1500-2000mL: Marked decrease in SBP, restlessness, pallor oliguria
• 2000-3000mL: Profound decrease in SBP, collapse, air hunger, anuria

Management

• Resuscitate
• Keep warm, O2
• Four T assessment
  • Tone: Fundus atonic
  • Trauma: Fundus firm, clotting blood
  • Tissue: Fundus atonic unresponsive to uterotonics
  • Thrombin: Fundus firm, blood not clotting
  • Unknown: Assess for rupture/inversion/concealed bleeding (e.g. subcapsular liver haematoma)
• 2x large bore IVC 14-16G
• FBC, UEC, LFT, Coags, VBG, ROTEM, X-match
• Transfuse early if ongoing bleeding – Consider MTP
• Tranexamic acid 1g IV over 10 min (WOMAN TRIAL showed possible reduced risk of death due to bleeding (1.5 vs. 1.9%; NNT = 267) with no reduction in overall death or hysterectomy rates

Tone

• Massage uterine fundus, assess need for bimanual compression, check placenta and membranes complete, expel uterine clots and insert IDC
• Active management of third stage prevents PPH
• First line drugs
  • Oxytocin 5IU IV over 1-2min. Can repeat at 5 minutes
  • Oxytocin 30IU in 500mL at 5-10IU/hour
  • Ergometrine 250mcg IM or IV over 1-2min
• Second-line
  • Prostaglandin F2alpha 250mcg IM or 500mcg intramyometrial
• If ongoing bleeding, arrange transfer to OT
• Check uterine cavity empty and intact under GA
• Bakri balloon tamponade
• Angiographic embolisation (90% effective)
• Laparotomy with aortic pressure below renal arteries
• B-Lynch compression suture
• Bilateral uterine artery ligation
• Bilateral utero-ovarian artery ligation
• Bilateral internal iliac artery ligation
• Hysterectomy

Trauma

• Attempt clamping of obvious arterial bleeding prior to repair
• Repair ensuring bleeding at apex of laceration is secured
• Transfer to OT for definitive care as wound visualisation is often suboptimal in ED
• Inspect cervix with two sponge holders, moving around one step at a time
• Replace uterine prolapse (painful ++ and need to stop any uterotonics to allow for this)

Tissue

• Express clots by cupping fundus in palm of dominant hand and compressing uterus
• Massage fundus firmly
• Use sponge holders to clamp membranes at introitus and without traction, rolls forceps to create a rope
• If retained placenta, insert IDC, consider additional oxytocin, transfer to OT for removal

DRUGS IN PREGNANCY

• Situations in which pregnancy category may be invalid
  • Overdose
  • Occupational exposure
  • Exceeding recommended therapeutic dose
• Categories
  • B does NOT imply greater safety than cat C – Only less evidence in humans
  • Medications in Cat D are NOT absolutely contraindicated in pregnancy
  • Category A – Taken by large number of pregnant women and women of childbearing age without any proven increase in frequency of malformations or other direct or indirect harmful effects on fetus having been observed
  • Category B – Taken by a limited number of pregnant women and women of childbearing age without an increase in frequency of malformations or direct/indirect harmful effects on fetus
    • B1 – Studies in animals have not shown an increased occurrence of fetal damage
    • B2 – Studies in animals are inadequate or may be lacking, but available data show no evidence of increased occurrence of fetal damage
    • B3 – Studies in animals have shown an increased occurrence of fetal damage, the significance of which is uncertain in humans
  • Cat C – Drug, owing to their pharmacological effect, have caused or are suspected of causing harmful effects to fetus without causing malformations. Effects may be reversible
  • Cat D – Drugs which have caused, or are suspected to have caused or may be expected to cause, an increased frequency of human fetal malformations or irreversible damage.
  • Cat X – Such a high risk of permanent damage to fetus that they should not be used in pregnancy or where there is a possibility of pregnancy

Cat A

• Adrenaline
• Antacids
• Ampicillin
• Atropine
• Benzathine penicillin
• BenPen
• Bisacodyl
• Bupivacaine
• Codeine
• Cortisone
• DExamethasone
• DIgoxin
• Doxylamine
• Erythromycin
• Metoclopramide
• Cephalexin
• Clindamycin
• Clotrimazole

B1

• Ondansetron
• Granisetron

B2

• Hyoscine

B3

• Sumatriptan

C

• Droperidol
• Prochlorperazine (Stemetil)

Cat D

• ACEi
• ARBs
• Anticonvulsants
• Oestrogens
• Tetracyclines
• Chlorpromazine

Cat X

• Misoprostol
• Raloxifene
• Ribavirin
• Tretinoin
• Isotretinoin

Last Updated on December 4, 2024 by Andrew Crofton