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

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.

INTRODUCTION

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→ 15%

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

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)

ANTENATAL TESTS(1ST Trimester)

OPTIONAL:

• PAPP-A

• Free ẞ-HCG

• Rubella

• RFT

• LFT

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.

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

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

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

TIMING OF TESTING IN PREGNANCY

• Unknown HIV status during labor-testing should be timed so that results are available to allow predeliveryadministration 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

HEPATITIS -B

• 90% of infants exposed to the hepatitis B virus at birth will develop life-long 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 perinataltransmission of HBV and the subsequent development of chronic HBV infection.

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)

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.

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.

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.

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.

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.

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.

Diagnosis(Hyperthyroidism)

• Occurrence of hyperemesis gravidarumleading 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

ẞ-HCG & PAPP-ADOUBLE 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.

PAPP-A and B-hCG

Implications of HCG Test

• Estimate gestational age

• Detect abnormal pregnancy

• Screening test for down syndrome

• Diagnose ectopic pregnancy

• Detect molar pregnancy.

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

hCG Distribution curves

>2.5 MoMs=Alert!!

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.

PAPP-A Distribution Curve

<0.4MoMs=Alert!!

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.

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.

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

• 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.

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’

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.

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.

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 .

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.

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.

Giving birth should be about giving life not

giving up a life.

THANK YOU !