ppt on "baseline serum chemistry in 1st trimester" by Dr.Rohit Jain,Assistant Professor,Obstetrics and Gynecology Department,Civil Hospital,BJ Medical College,Ahmedabad

1. BASELINE SERUM CHEMISTRY IN
FIRST TRIMESTER
Dr.Rohit Jain
MD(Ob/Gyn)
Assistant Professor,Dept of Obs&Gyn
B.J Medical College,Civil Hospital
Ahmedabad

2. INTRODUCTION
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Good care during pregnancy is important for the health of the
mother and the development of the unborn baby.
Inadequate care during this time breaks the critical link in the
continuum of care, and effects both women and babies.

3. INTRODUCTION
⅓
3%
→
15%

4. GOALS OF ANC
• Screening and prevention of diseases that may
complicate pregnancy.
• To monitor the progress of pregnancy in order to ensure
maternal health and normal fetal development.
• To recognize the deviation from the normal and provide
management or treatment as required.
• To identify high risk pregnancy and for their proper
management.
• To reduce or prevent maternal and perinatal mortality
and morbidity

5. ANTENATAL TESTS
(1ST Trimester)
ROUTINE:
• HIV
• Hbs Ag
• TFT’s
• VDRL/RPR( Syphilis)
• CBC
• Blood Group
• RBS
• Hemoglobinopathies( Thalassemia & Sickle cell)
• Urine
• PAP Smear( if due)

6. ANTENATAL TESTS
(1ST Trimester)
OPTIONAL:
• PAPP-A
• Free ẞ
-HCG
• Rubella
• RFT
• LFT

7. HIV TESTING
• “Rapid” HIV antibody tests available since 2002.
Agency for Healthcare Research and Quality (AHRQ) &
U.S. Department of Health and Human Services say:
• Identification and treatment of asymptomatic HIV infection in
pregnant women can result in major reductions in MTCT rates.
• In settings with a maternal prevalence of 0.15%, the estimated
number needed to screen to prevent one case of MTCT ranged
from 3,500 to 12,170, and in settings with a maternal prevalence of
5%, ranged from 105 to 365.

8. BENEFITS OF HIV TESTING
• allow appropriate evaluation
– CD4 count & viral load quantification
• allows the interventions to prevent MTCT to be
initiated
– ARV prophylaxis, mode of delivery (elective CS or vaginal),
and avoidance of breastfeeding

9. CONSENT FOR HIV TESTING
(CDC Recommendations)
• Universal HIV screening of pregnant women with “opt-out”
consent .
• HIV screening should be included in the routine panel of
prenatal screening tests and separate written consent for HIV
testing should not be required

10. TIMING OF TESTING IN PREGNANCY
• Early in pregnancy -timely therapeutic decision and
prevention of MTCT
• Second test(CDC recommendation)- late in pregnancy (at
36 weeks):
-in areas of high incidence
-women delivering in hospitals with HIV
prevalence in pregnant women of at least 1 in 1000
-women at high risk of acquiring HIV
-women with signs/symptoms of acute HIV
infection

11. TIMING OF TESTING IN PREGNANCY
• Unknown HIV status during labor-testing should be
timed so that results are available to allow predelivery
administration of prophylaxis if indicated
• Postpartum mother with unknown HIV status -testing
should be performed quickly enough so that results can
be available for infant ARV prophylaxis to begin within 12
hours of birth

12. HEPATITIS -B
• 90% of infants exposed to the hepatitis B virus at birth will develop lifelong chronic infections.30% -40% of all chronic HBV infections result from
perinatal transmission. Chronic HBV infections increase long-term
morbidity and mortality (cirrhosis of the liver and liver cancer)
USPSTF/CDC/ACOG
• Recommends screening of all pregnant women in first
trimester, even if they have been previously vaccinated or
tested.
• They have found convincing evidence that universal prenatal
screening for HBV infection substantially reduces perinatal
transmission of HBV and the subsequent development of
chronic HBV infection.

13. HEPATITIS-B TEST
A test for HBsAg should be ordered at the first
prenatal visit with other recommended screening
tests.
• Effective screening tool for HBV:
Serologic identification of hepatitis B surface antigen
(HBsAg)

14. Syphilis
• More than 80% of women with syphilis are of
reproductive age; therefore, there is a serious risk of
vertical transmission to the fetus.
• USPSTF strongly recommends that clinicians screen
all pregnant women for syphilis infection.
• CDC recommends RPR card test for syphilis on all
pregnant women at the first prenatal visit.

15. Syphilis
• T. pallidum readily crosses the placenta.Vertical transmission
can occur at any time during pregnancy and at any stage of
syphilis
• 70-100% per cent of infants born to untreated infected
mothers are infected
• Effects→ intrauterine growth restriction,hydrops, stillbirth,
preterm delivery, and spontaneous abortion in up to 50% of
pregnancies.

16. Tests for Syphilis
Non-treponemal tests
• VDRL (venereal disease research laboratory) test: simple,
inexpensive.
• RPR (rapid plasma reagin) test: used for screening
purposes, least technically demanding test as no
microscope is needed & requires a minimal quantity of
blood.

17. Screening for Thyroid disease in
Pregnancy
ACOG/ATA/SOCIETY OF FETOMATERNAL
MEDICINE:
• Do not recommend universal screening but in pts with:
-a personal history of thyroid disease,
-a positive family history,
-type 1 diabetes mellitus
-infertility
-history of miscarriage or preterm delivery
-clinical signs or symptoms of thyroid disease that would
classify them as high risk.

18. Diagnosis(Hypothyroidism)
• ↑S.TSH ≥ 4mIU/L
• ↓T3 / T4
(As low T4 even with normal TSH, is now considered
abnormal especially in iodine deficient zones )
Recent studies suggests that the upper limit
of normal TSH in the first trimester of
pregnancy should be 2.5 mIU/L.

19. Monitoring of TFTs
• Pregnant women with hypothyroidism
First Half: Every 2 to 4 wks
Second half: Every 4 to 8 wks
as this time interval has been shown to identify 90% of
abnormal TSH values that resulted in Levothyroxine dose
adjustment.

20. Diagnosis(Hyperthyroidism)
• Occurrence of hyperemesis gravidarum
leading to wt loss must always think of
thyrotoxicosis!
• ↓S.TSH < 0.1mIU/L
• ↑T3 & T4
• In 1st trimester S.TSH is suppressed ( < 0.2
mIU/L ) at time of peak hCG levels

21. ẞ
-HCG & PAPP-A
DOUBLE MARKER TEST
• Biochemical markers for Screening of DS in the 1st trimester
• Determine the overall risk of Down’s syndrome in the fetus.
• Measured at 10-13 completed weeks.
• Calculation of the Multiple of Median (MoM)
• Overall, the normal value for different markers is 1 MoM.
The farther away from 1 MoM the marker's result is, the
worse the result is.

22. PAPP-A and B-hCG

23. Implications of HCG Test
• Estimate gestational age
• Detect abnormal pregnancy
• Screening test for down syndrome
• Diagnose ectopic pregnancy
• Detect molar pregnancy.

24. ẞ
-HCG Values
WEEKS FROM LMP
B HCG (MIU/ML)
3
5-50
4
5-426
5
18-7340
6
1080-56500
7-8
7650-288000
9-12
25700-288000
13-16
13300-254000
17-24
4060-165400
25-40
3640-117000
NON- PREGNANT
<5
POST-MENOPAUSAL
<9.5

25. hCG Distribution curves
>2.5 MoMs=Alert!!

26. Pregnancy Associated Plasma
Protein A (PAPP- A)
• Placental protein which continues to increase during the
pregnancy.
• Glycoprotein synthetized in chorionic villi.
• Serum levels lower in Down’s pregnancies in 1st trimester.

27. PAPP-A Distribution Curve
<0.4MoMs=Alert!!

28. Evidences
(Double Marker Test)
• Reduction in birth prevalence of DS associated with
offering prenatal diagnosis to women ( ≥35 yrs) range
from 7.3% to 29%.
• Limited data are available to estimate the impact of
serum-marker screening in women(<35yrs) on DS birth
prevalence.

29. RUBELLA: ( German Measles).
• Risk of fetal transmission:
primary maternal infection
-in 1st month of gestation- 50-60%
-in the 2nd month
- 22%
-in the 3rd to 4th month - 6-10%
• The fetus is most at risk in the first 16 weeks gestation.

30. TEST FOR RUBELLA
• Routine blood test performed as part of prenatal care of pregnant
women
• Serological testing(IgM & IgG Abs) with EIA
• IgG positive→ Immune
• IgM positive→recent rubella infection

31. • Advisory Committee on Immunization Practices (ACIP) &
USPSTF recommends screening of all women of childbearing
age, including pregnant women, for rubella susceptibility
during their first clinical encounter.
• Screening pregnant women allows clinicians to identify at-risk
women and to encourage them to be immunized immediately
after delivery, thereby offering protection during subsequent
pregnancies.

32. Screening for Haemoglobinopathies
– Screen all women for sickle cell diseases and
thalassaemias (ideally by 10 weeks)
– The type of screening depends upon the
prevalence and can be carried out in primary or
secondary care
- high prevalence: laboratory screening
- low prevalence:‘Family Origins Questionnaire’

33. Thalessemia Screening
• Essential in 1st trimester to diagnose at early gestation
• HPLC( High performance Liquid Chromatography)
• ↑ HbA2 ẞ4% & ↑ HbF
• Assessment of iron status ,total iron binding
capacity,ferritin level are important in differentiating
thalessemia from iron deficiency anemia.

34. Renal Function Test
• ↑GFR resulting in ↓ urea , creatinine & uric acid.
• Renal tubular threshold is also decreased during
pregnancy leading to increased excretion of glucose,
amino acid , uric acid.
• Resulting in physiological glycosuria of pregnancy.

35. Liver Function Test
• All markers (total billirubin, AST ,ALT, albumin) are
reduced during pregnancy due to physiological expansion
of extracellular fluid
• Only exception is ALP which is raised due to its placental
origin .

36. Calcium Metabolism
• Serum calcium,phosphate, magnesium tends to low
because of increased intravascular volume.
• Serum parathyroid hormone level is 50% of normal level
despite increased urinary excretion of calcium.

37. Carbohydrate Metabolism
• Concentration of fasting glucose is reduced due to
increased utilisation.
• Increased incidence of obesity tends to increase incidence
of gestational diabetes and type 2 diabetes mallitus.
• FBS,PPBS,RBS,HbA1c are important serological
markers.

38. Giving birth should be about giving life not
giving up a life.
THANK YOU !