Serology of pregnancy

Why do we screen for pregnancy?

• Before medical procedures to prevent harm to the fetus

• To determine if early genetic counseling is needed

• To detect conditions like trophoblastic tumors, choriocarcinoma, testicular tumors

• Detected ectopic pregnancy

What is HCG?

Human chorionic gonadotropin. A glycoprotein secreted by the trophoblastic cells that helps to maintain placental health.

When is HCG detected and when does it peak?

With in few days after conception and peaks after 2-3 months

How many subunits does HCG have?

Two, the alpha and beta subunits

Is the alpha subunit of HCG shared with other molecules in the body?

Yes shared with TSH, FSH and LH

In the beta subunit of HCG shared with any other molecules in the body?

No, it is unique to HCG.

What is the clinical usefulness of HCG?

• high risk pregnancies

• ectopic pregnancy

• trophoblastic tumors

• testicular tumors

What makes a pregnancy high risk?

• maternal age

• diabetes

• Autoimmune disorders

• previous miscarriages or pre-term deliveries or deaths

• substance abuse

• multiple births

What is an ectopic pregnancy?

When a fertilized egg implants outside the uterus

What are 95% of ectopic pregnancies?

Tubal pregnancies where the egg implants in the fallopian tubes

What can an ectopic pregnancy results in?

• rupturing

• inflammation and scarring of tubes

• bleeding

• death

What is a hydatiform mole?

An intrauterine neoplastic mass arising from the chorion (embryonic sac). The chorionic villi enlarge into grapelike clusters

What are complete and partial moles?

Complete: No fetal tissue

Partial: Fetal and trophoblastic tissue

• in rare cases a normal fetus and a mole co-exist

What is a choriocarcinoma?

An epithelial malignancy of fetal origin. Developed from the chorionic portions of the products of conception.

What do choriocarcinomas originate from?

Hydatid moles

What are testicular tumors?

Embryonic germ cell tumors with cells from all three germ layers

Which trophoblastic tumors produce HCG?

All of them

What are the testing methods for pregnancy?

Older:

• Direct agglutination

• agglutination inhibition

Current:

• monoclonal antibody test

What are the organisms tested for in the torch test?

• toxoplasmosis

• rubella

• cytomegalovirus

• herpes

Why do we test for toxoplasmosis?

Can result in CNS malformation or prenatal mortality in neonates

Neonates without symptoms at birth may later develop chorioretinitis, blindness or other neurological problems

What is toxoplasmosis?

A coccidian parasite. Definitive host is the house cat.

What form of toxoplasmosis invades the neural tissue?

Tachyzoites

What do tachyzoites differentiate into to form dormant tissue cysts?

Bradyzoites

What form of toxoplasmosis can be transmitted to the baby via the blood stream?

The tachyzoites which localize to neural tissue of muscle tissue in the baby

How can infection with toxoplasmosis be avoided?

• avoiding raw meat

• avoiding handling the litter box

What is the treatment for toxoplasmosis?

• pyrimethamine and sulfadiazine

• treat baby for first two weeks after birth

What is rubella?

A ssRNA virus of the togavirus family. Also called the german three day measles

Why test for rubella?

Incubation is 3-5 days, contagious for 12-15 days beginning 5-7 days before the appearance of the rash

Once infected with rubella you are usually?

Immune for life.

What is considered an immune titer for rubella?

An IgG titer of 1:8 to 1:10.

IgM is used to test for recent infections

What are the risks during pregnancy of rubella?

• preconception: minimal

• 0-12 weeks: 100% risk of fetus being congenitally infected

• 13-16 weeks: deafness and retinopathy 15%

• after 16 weeks: normal development, slight risk of deafness and retinopathy

Who should be tested for rubella?

• women of childbearing age

• pregnant women

• healthcare workers

What is cytomegalovirus?

A virus belonging to the herpes family. Associated with WBCs

How can cytomegalovirus be transmitted?

Through respiratory secretions, blood, urine and breast milk

What populations are at risk for CMV?

Immunocompromised

• HIV patients

• transplant patients

• premature infants

What is the key viral effect of CMV on tissue?

Owl eye inclusions

How do we reduce the risk for CMV?

Use blood products that are CMV negative and free of WBCs

What is herpes simplex virus?

A virus that integrates its DNA into its host’s.

How is herpes transmitted?

By infections secretions or lesions