Preconception Counselling (PreTest Notes) Flashcards Preview

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Flashcards in Preconception Counselling (PreTest Notes) Deck (48):

How does an initial spontaneous abortion affect the risk of recurrence in future pregnancy?

The risk remains the same. An initial spontaneous abortion regardless or karyotype or gender of the child does not change the risk of recurrence in future pregnancy


What proportion of spontaneous abortions in the first trimester are found to have chromosomal abnormalities?



What is the most common group of chromosomal abnormalities causing first trimester loss?

Autosomal trisomies


What is the most common single anomaly found in first trimester miscarriage?

45X (Turner syndrome)


What screening should be done for patients with recurrent miscarriage?

-Parental karyotype
-Thyroid function
-Collagen vascular disorders
-Lupus anticoagulant


Why should a hysterosalpingogram be ordered in second trimester pregnancy loss?

Rule out uterine structural abnormalities e.g.:
-bicornuate uterus
-septate uterus
-unicornuate uterus


When does paternal age contribute to aneuploidy?

Father age ~55+


The risk of what genetic conditions are most increased with increased paternal age?

Point mutations


When is the optimal time for NT measurement?

12-13 weeks


What are the sequelae of alcohol consumption during pregnancy?

-craniofacial abnormalities
-mental retardation
-cardiac anomalies
-joint defects


What effect do tetracyclines have on the foetus in utero?

Interfere with bone development and may produce stained teeth


How should patients who have inadvertently become pregnant on birth control pills be counselled?

-Incidence of birth defects is no higher for them than the general population.
-Progesterone implicate in multiple birth defects but studies failed to demonstrate significant association with increased risk.


What is the assumed threshold for increased foetal risk from radiation?

10 rads


Achondroplasia pattern of inheritance?

Autosomal dominant


What accounts for 90% of achondroplasia?

New mutations


What are the special considerations in managing a pregnant patient with achondroplasia?

-C section due to distorted maternal pelvis
-C section to protect foetus neck if also has achondroplasia
-Spinal stenosis may make spinal / epidural anaesthesia more challenging


What is the likelihood of a child of a 46XY father and mother who carries a balanced 13;13 translocation having chromosomal abnormality? Why?

100%: carriers of a balanced translocation of the same chromosome are phenotypically normal BUT in the process of gamete formation the translocated chr cannot divide and therefore meiosis products end up with either 2 or 0 copies of the chr.


Which monosomies can be live births?

Everything lethal except monosomy X (Turner)


What is an encephalocele?

Version of a NTD involving outpouching of neural tissue through a defect in the skull


What is a cystic hygroma?

Emerges from base of neck with an intact skull present; easily confused with encephalocele


What is the MSAFP used to screen for?

Offered 15-21 weeks gestation to screen for NTDs


MSAFP cutoff?

2.5 MoM (multiples of median)


What should be conducted if elevated MSAFP?

Genetic amniocentesis: elevated AFP and acetylcholinesterase in amniotic fluid. If both elevated, identifies 100% cases of anencephaly and open NTDs.


What is the incidence of NTDs?

1.4-2.0 / 1000


When can amniocentesis be performed?

15-20 weeks


When can CVS be performed?

10-13 weeks


Compare the amniocentesis and CVS pregnancy loss rates

-Mid trimester amniocentesis has procedure related foetal loss rate of 1: 300 - 500
-CVS has higher complication rate BUT may be due to higher baseline pregnancy loss rate at 9 - 16w


Which vaccine types are considered safe in pregnancy?

Vaccines that contain killed antigens, virus like particles or noninfectious components of bacteria (e.g. tetanus toxoid, Tdap, influenza)


Can you give HepB vaccine during pregnancy?

Yes, not contraindicated during pregnancy. Give to pregnant women at high risk.


What are the complications of tetracycline during pregnancy for the foetus?

-foetal dental anomalies
-inhibition of bone growth if administered in second and third trimesters
-potent teratogen in first trimester foetus


What are the complications of tetracycline for the mother if given during pregnancy?

-Severe hepatic decompensation if given in the third trimester


What are the complications of chloramphenicol administration to the neonate?

Grey baby syndrome:
-impaired respiration
-CV collapse


Can trimethoprim-sulfamethoxazole (bactrim) or other sulpha drugs be used in the third trimester?

No. Can cause kernicterus


Are morbidly obese women who do not gain weight during pregnancy at risk of foetal growth abnormalities?

No. It is not recommended obese women gain weight during pregnancy, however dietary restriction and weight loss are to be avoided.


What conditions is smoking during pregnancy associated with?

-Foetal growth restriction
-Spontaneous abortion
-placenta praevia
-preterm delivery


What are the mechanisms for the increased incidence of certain condition if a woman smokes during pregnancy?

-Increased foetal carboxyhaemoglobin levels
-Reduced uteroplacental blood flow
-Foetal hypoxia


If a woman with epilepsy ceases her medications during pregnancy, how will this alter the child's risk of congenital anomalies?

Will still have 2-3x the risk of congenital anomalies as seizures cause a transient reduction in uterine flow and foetal oxygenation.


Recommendation for pregnant women with epilepsy prior to becoming pregnant?

Trial a weaning off of medications prior to becoming pregnant


What is foetal exposure to sodium valproate associated with?

1-2% risk spina bifida


If a woman must take anti convulsants during pregnancy, what are the recommendations to minimise congenital anomalies?

-Monotherapy better than multiple medications
-Folate supplementation (many anti convulsants impair folate metabolism)


What are the issues with vitamin C supplementation during pregnancy?

No known issues with Vit C supplementation during pregnancy


What is sickle cell anaemia and how may it cause pain?

Autosomal recessive condition that is common in people of African origin. Low oxygen conditions cause the cells to become distorted (sickle) and this can lead to vasoocclusive crisis causing severe pain.


How is neurofibromatosis inherited?

Autosomal dominant (+50% occur from sporadic mutations)


G6PD inheritance pattern?

X linked recessive


Which antibiotics are associated with kernicterus in the newborn?



How do sulphonamides cause kernicterus?

Compete with bilirubin for binding sites on albumin thereby leaving more bilirubin free for diffusion into tissues


Can MMR and VZV be given during pregnancy?

No. Foetal effects unknown. Wait 1 month after vaccination for pregnancy


Can HPV be given during pregnancy?

No. If becomes pregnant during course (3 doses) withhold remainder until after delivery