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Case 4.2 – Antenatal Care

Category: Medicine | Discipline: Obstetrics & Gynaecology | Setting: General Practice

Case

Phillipa Wong presents for pregnancy care. She had her last period 8 weeks ago and a chemist pregnancy test was positive. She and her husband have been trying to conceive for 4 months. She complains of nausea and vomiting.

Questions

1. Describe the biochemistry of the pregnancy test and how it is used in diagnosing an abnormal pregnancy. Should Phillipa's home pregnancy test be repeated?

Biochemistry of Pregnancy Test:

Urine pregnancy test measures the amount of beta HCG (human chorionic gonadotropin) excreted in the urine to a sensitivity of 50 IU/L. Beta HCG is specific to pregnancy - the alpha form comes from other gonadotrophins like LH.

Timing:

  • Can be detected before the first missed period (about day 10-12 from conception)
  • Approximately day 24-26 of cycle if perfect 28 day cycle

Use in Diagnosing Abnormal Pregnancy:

  • Quantitative beta HCG gives a concentration of HCG
  • The level doubles every 48 hours in normal pregnancy
  • Falling serial levels indicate a failed pregnancy
  • Abnormally rising levels may indicate ectopic pregnancy or molar pregnancy

Should the test be repeated?

Yes, pregnancy should be confirmed by repeat testing to ensure accurate diagnosis and establish a baseline for monitoring.

2. What are the signs and symptoms of early pregnancy? List the recommendations for nausea and vomiting in pregnancy.

Signs and Symptoms of Early Pregnancy:

  • Amenorrhoea (missed period)
  • Nausea and vomiting
  • Breast tenderness and enlargement
  • Increased urinary frequency
  • Pigmentation of areola
  • Fatigue

Recommendations for Management of Hyperemesis Gravidarum:

Presentation ranges from mild to severe

Initial Assessment

  • 1st trimester ultrasound to exclude multiple gestation and molar pregnancy
  • Reassurance that hyperemesis will not harm foetus if hydration maintained

Conservative Management

  • Increased rest, leave from work as needed
  • Increased fluid intake
  • Ginger tea and tablets may help

Pharmacological Management

  • Vitamin B6 75mg daily
  • Anti-emetic medication - increase as needed, dopamine antagonists
  • Ondansetron wafers

Hospital Admission Indications

If dehydrated or urinary ketones present:

  • Admit for intravenous therapy and potassium replacement
  • Thiamine to prevent Wernicke's encephalopathy
3. What history and examination would you undertake at a first visit with a pregnant woman?

Comprehensive First Visit History and Examination:

Gynaecological History

  • Menstrual history
  • Previous contraception
  • Last cervical screening test
  • LMP (Last Menstrual Period)

Obstetric History

  • Number of pregnancies
  • Outcomes of each pregnancy
  • Gestation of each pregnancy
  • Type of delivery
  • Complications
  • Breastfeeding history

Medical History

  • Particularly renal disease, diabetes, or hypertension

Surgical History

  • Particularly gynaecological surgery, appendicectomy

Family History

  • Congenital abnormalities (anything in the family at all)
  • Twinning
  • History of own birth

Medication History

  • Over-the-counter medications
  • Prescribed medications
  • Herbal supplements
  • Including anything ceased since discovery of pregnancy

Social History

  • Partner and family support
  • Work nature and type
  • Housing
  • Alcohol, smoking, caffeine use

Ethnic Background

  • Asian - higher risk of haemoglobinopathies
  • Horn of Africa - risk of genital mutilation

Other Important Information

  • Allergies
  • Vegetarian diet
4. Which routine investigations are ordered as part of antenatal care?

Routine Antenatal Investigations by Timing:

First Visit (Around 10+ weeks)

Investigation Purpose
Blood Group: ABO Identify blood type for potential transfusion needs
Rhesus factor & Antibody screen Identify Rh negative mothers requiring Anti-D prophylaxis
FBC/Ferritin Screen for anaemia (especially if heavy menses history)
Rubella Check immunity status
TPHA Screen for syphilis
Hepatitis B and C Screen for chronic hepatitis
HIV Screen with pre-test counselling
Vitamin D If dark skinned or little sun exposure
Urine M/C/S Screen for asymptomatic bacteriuria
TSH If overt hypothyroidism suspected
Dating ultrasound If indicated - confirm dates and viability

11-13 Weeks

  • Down's syndrome screen (nuchal translucency + serum PAPP-A and beta HCG)

18-20 Weeks

  • Morphology ultrasound (foetal anomaly scan)

26 Weeks

  • 75 gram glucose tolerance test (GCT/GTT)
  • FBC
  • Blood group and antibody screen

34 Weeks

  • FBC
  • Blood group and antibody screen
  • Vaginal swab for Group B Streptococcus screen

Additional Investigation

  • Influenza vaccine offered at initial visit
5. Describe the common models of antenatal care in Australia.

Common Models of Antenatal Care in Australia:

1. Midwifery-Led Care

  • Midwifery care for antenatal care (ANC) and delivery
  • Suitable for low-risk pregnancies
  • Continuity of care with same midwife/team

2. GP-Led Care (Shared Care)

  • Usually GP provides antenatal care
  • Delivery occurs in hospital environment (either midwifery or obstetric)
  • Popular model for low-risk pregnancies

3. Obstetrician-Led Care

  • ANC and labour provided by Obstetrician & Gynaecologist
  • Indicated for high-risk pregnancies
  • Hospital-based care

4. Multidisciplinary Teams

  • ANC provided by multidisciplinary team
  • Labour in hospital under O&G care
  • For complex pregnancies requiring multiple specialties

Routine Low-Risk Antenatal Care Schedule

The Royal Women's Hospital utilises a routine antenatal care schedule of 10 visits.

This represents a reduced number of content-specific, longer consultations compared with the traditional 14 visits for well women, and is considered best practice in terms of:

  • Perinatal outcomes
  • Client satisfaction
  • Cost effectiveness

However, with reference to flexibility and consumer-centred care, a woman may desire an increased number of visits and should be given this opportunity.

Typical Visit Schedule

Timing Care Provider Key Activities
10+ weeks Consultant/Registrar & Midwife Initial assessment, booking bloods, dating ultrasound
16 weeks Midwife/GP Standard check, review results
20 weeks Midwife/GP Standard check, review morphology ultrasound
26 weeks Midwife Standard check, GCT, FBE, antibodies, PAC
30 weeks Midwife/GP Standard check
33-34 weeks Midwife/GP Standard check (34 weeks if Anti-D needed)
36 weeks Consultant/Registrar Consultant review, GBS screen
38 weeks Midwife/GP Standard check
40 weeks Midwife/GP Standard check, provide CTG/AFI request
41 weeks Consultant/Registrar Consultant review, CTG/AFI prior to appointment
6. Discuss the role of 1st, 2nd and 3rd trimester ultrasound in pregnancy.

Role of Ultrasound Throughout Pregnancy:

First Trimester Ultrasound

Dating Scan:

  • Unsure dates
  • Contraceptive use within 3 months
  • Uterine size not proportionate to dates

Pregnancy Viability:

  • Determining viable pregnancy versus miscarriage
  • Incomplete miscarriage
  • Molar pregnancy
  • Ectopic pregnancy

First Trimester Screening (11-13 weeks):

  • Nuchal fold thickness measurement
  • Screening test for Trisomy 21 (Down syndrome) when combined with serum PAPP-A and beta HCG

Second Trimester Ultrasound (18-20 weeks)

  • Foetal anomaly scan - detailed anatomical survey
  • Placental localization - identify placenta praevia

Third Trimester and Additional Indications

Further scans may be indicated for specific clinical issues:

Antepartum Haemorrhage (APH):

  • Identify cause and assess foetal wellbeing

Size-Date Discrepancy:

  • Fundal height is small or large for dates

Pregnancy Complications:

  • Diabetes, renal disease, pre-eclampsia
  • Check foetal welfare including:
    • Growth parameters
    • Foetal biometry
    • Breathing movements
    • Tone
    • Doppler studies of umbilical artery checking for blood flow

Multiple Pregnancy:

  • Serial monitoring of foetal growth in twins and high-risk pregnancies

At Term:

  • Unstable lie at term
  • Abnormal foetal presentation
  • Placental location if previous scans show low-lying placenta