Early Pregnancy Flashcards
What is RhD sensitization and why is it important in pregnancy?
RhD sensitization occurs when a Rh-negative individual is exposed to Rh-positive blood, leading to the development of antibodies. This can cause complications in future pregnancies, especially if a Rh-negative woman carries a Rh-positive baby, leading to hemolytic disease of the fetus and newborn (HDFN).
In the UK, around 85% of the population are RhD positive. The RHD gene is dominant so one copy from either parent makes pos.
Dose of anti-D
The recommended minimum dose for treating fetomaternal hemorrhage (FMH) is 500 IU for up to 4 mL of fetal red cells. Additional doses are based on the volume of fetal cells, calculated at 125 IU per 1 mL of fetal red cells.
When should anti-D immunoglobulin (anti-D Ig) be administered?
Anti-D Ig should be given to D-negative pregnant women after events like
1. Sensitising events: miscarriage, trauma, invasive procedures (amniocentesis),
2. At 28 and 34 weeks of pregnancy as routine prophylaxis for non-sensitized D-negative women carrying an Rh-positive fetus,
3. After delivery of a Rh-positive baby ( within 72 hours ).
What is the purpose of anti-D Ig after a sensitizing event or delivery of a Rh-positive baby?
Anti-D Ig is used to prevent RhD sensitization by clearing Rh-positive fetal red cells from the maternal circulation, preventing complications in future pregnancies.
What is the safety profile of anti-D Ig?
Anti-D Ig is derived from pooled plasma and undergoes safety measures like screening for viruses. Adverse reactions are rare but may include allergic reactions or anaphylaxis, especially in those with IgA antibodies.
What are the available preparations of anti-D Ig in the UK?
D-GAM® (IM use only) and Rhophylac® (IM or IV use) are the main preparations available. D-GAM® is not suitable for IV use due to the risk of severe hypersensitivity.
How should anti-D Ig be administered?
Anti-D Ig is typically administered intramuscularly (IM) in the deltoid muscle. In women with bleeding disorders, IV or subcutaneous administration may be preferred. Doses are calculated based on FMH testing results.
What should be done if anti-D is detected in a sample from a pregnant woman?
The source of anti-D (immune or passive) should be determined. If it is unclear, prophylaxis should continue according to guidelines for D-negative women.
Passive vs Immune Anti-D Detection:
After anti-D Ig administration, detectable anti-D may be passive (from the injection) or immune (produced by the body). If anti-D is detected in a pregnant woman at 28 weeks, investigations should determine its origin. If it is unclear, prophylaxis should continue to be administered as per guidelines for D-negative women.
Timeline of Rh testing
Early Pregnancy: Blood tests check for blood group and if RhD-negative, additional check for anti-D antibodies
If NO anti-D antibodies: blood is rechecked at 28 weeks, and an anti-D immunoglobulin injection is offered to prevent rhesus disease.
If YES anti-D antibodies: closer monitoring is required. If a Doppler ultrasound shows faster-than-normal blood flow in the baby, foetal blood sampling (FBS) may be performed to check for anaemia.
At Birth: Blood is taken from the baby’s umbilical cord (Coombs test) to check their blood group and for anti-D antibodies.
If the mother has anti-D antibodies, the baby’s blood is tested for iron deficiency anaemia and newborn jaundice.
Future Testing: Routine testing may identify the baby’s RhD status to avoid unnecessary treatment for RhD-negative women without antibodies.
What is hemolytic disease of the fetus and newborn (HDFN)
A condition where fetal red blood cells are destroyed due to blood group incompatibility, primarily involving Rh or ABO blood types.
Leading to hemolysis, anemia, and hyperbilirubinemia.
Rh incompatibility usually affects subsequent pregnancies because maternal sensitization occurs during the first pregnancy, leading to more severe complications such as intrauterine hydrops fetalis in later pregnancies.
ABO incompatibility, however, can impact the first pregnancy since maternal antibodies preexist.
Diagnosis can occur before or after birth through laboratory tests and imaging studies, and treatments range from phototherapy and supplementation to transfusions in severe cases.
Most common: Rh-negative mother is sensitized to Rh-positive fetal red blood cells.
What are common clinical manifestations of HDFN?
Neonatal jaundice, anemia, hydrops fetalis (in severe cases), hypotonia and kernicterus in untreated cases.
Around 50% of babies diagnosed with rhesus disease have mild symptoms that are easily treatable.
Symptoms can sometimes develop up to 3 months afterwards.
How is HDFN diagnosed antenatally?
Maternal tests: ABO and Rh typing, antibody screening, and titer monitoring.
Fetal tests: Ultrasound for hydrops fetalis, Doppler ultrasound of the middle cerebral artery (high flow in anaemia), and amniocentesis for bilirubin levels.
What is the key postnatal test for HDFN?
A positive direct antiglobulin (Coombs) test, along with anemia, reticulocytosis, and hyperbilirubinemia in the neonate.
What conditions should be considered in the differential diagnosis of HDFN?
Physiologic jaundice, prematurity, G6PD deficiency, thalassemia, sepsis, Gilbert syndrome, hypothyroidism.
Polyhydramnios and placentomegaly from various fetal conditions.
Nonimmune hydrops fetalis from cardiac, chromosomal, or infectious causes
What are some signs suggesting nonimmune hydrops fetalis?
Cyanosis unresponsive to oxygen (cardiac disease).
Hypotonia (congenital myopathy or hypothyroidism).
Hepatosplenomegaly with dysmorphism (metabolic storage diseases).
Dermatitis with hepatosplenomegaly (TORCH infections).
What are complications of untreated severe HDFN?
Hydrops fetalis.
Kernicterus.
Anemia.
Long-term neurological dysfunction.
Complete molar pregnancy
duplication of a single spermatozoa inside an empty ovum (75-80%) or dispermic fertilisation of an empty ovum (20-25%).
They contain two sets of paternal chromosomes with a karyotype of 46 XX (most commonly) or 46 XY.
Partial molar pregnancy
dispermic fertilisation of a normal ovum (90%) and contain one set of maternal chromosomes and two sets of paternal chromosomes with a karyotype of 69 XXX (most commonly), 69 XXY or 69 XYY
Molar pregnancy: presentation
Irreg PV bleeding
+ve PT
USS features
Less common presentations:
hyperemesis, excessive uterineenlargement, hyperthyroidism, early-onset pre-eclampsia and abdominal distension due totheca lutein cysts.
Very rarely women can present with haemoptysis or seizures due to metastatic diseaseaffecting the lungs or brain.
Molar pregnancy: Can oxytocic infusions be used during surgical removal?
The use of oxytocic infusion prior to completion of the removal is not recommended.
If the woman is experiencing significant haemorrhage prior to or during removal, surgical removal should be expedited and the need for oxytocin infusion weighed up against the risk of tissue embolisation
How should women with an elevated human chorionic gonadotrophin after a possible pregnancy event be managed?
Referral to a GTD centre should be considered for all women with persistently elevatedhuman chorionic gonadotrophin (hCG) either after an ectopic pregnancy has been excluded, orafter two consecutive treatments with methotrexate for a pregnancy of unknown location.
Which women should be investigated for GTN after a non-molar pregnancy?
Any woman who develops persistent vaginal bleeding after a pregnancy event is at risk ofhaving GTN.
A urine hCG test should be performed in all cases of persistent or irregular vaginal bleeding lasting more than 8 weeks after a pregnancy event.
Symptoms from metastatic disease, such as dyspnoea and haemoptysis, or new onset ofseizures or paralysis, can occur very rarely.
Biopsy of secondary deposits in the vagina can cause major haemorrhage and is notrecommended.
What is the optimum follow-up following a diagnosis of GTD?
For complete molar pregnancy, if hCG has reverted to normal within 56 days (2 months) of the pregnancy event then follow-up will be for 6 months from the date of uterine removal.
If hCG has not reverted to normal within 56 days of the pregnancy event then follow-up will befor 6 months from normalisation of the hCG level.
Follow-up for partial molar pregnancy is concluded once the hCG has returned to normal on two samples, at least 4 weeks apart.
What is the optimum treatment for GTN?
Women with GTN may be treated with single-agent or multi-agent chemotherapy.
Treatment used is based on the FIGO 2000 scoring system for GTN following assessment at the treatment centre.
PSTT and ETT are now recognised as variants of GTN. They may be treated with surgerybecause they are less sensitive to chemotherapy.
What is the recommended interval between a complete or partial molar pregnancy and trying toconceive in the future?
Women are advised not to conceive until their follow-up is complete.
Women who undergo chemotherapy are advised not to conceive for 1 year after completion of treatment, as a precautionary measure.
What is the monitoring of women following a successful pregnancy after a previous molar pregnancy?
Women who have a pregnancy following a previous molar pregnancy, which has not required treatment for GTN, do not need to send a post-pregnancy hCG sample.
Histological examination of placental tissue from any normal pregnancy, after a molar pregnancy, is not indicated.
