Amniocentesis is used in all of the following conditions, except:
Correct Answer D: In amniocentesis, a needle is inserted transabdominally into the amniotic sac to withdraw amniotic fluid and fetal cells for testing, including measurement of chemical markers (eg, alpha-fetoprotein, acetylcholinesterase). The safest time for amniocentesis is after 14 weeks gestation. Immediately before amniocentesis, ultrasonography is done to assess fetal cardiac motion and determine gestational age, placental position, amniotic fluid location, and fetal number.
Amniocentesis has traditionally been offered to pregnant women > 35 because their risk of having an infant with chromosomal abnormalities (eg Trisomy), neural tube defects and metabolic errors are increased. Amniocentesis is not a method used to diagnose genitourinary anomalies.
The commonest indication for amniocentesis is:
Correct Answer C:
The indications for amniocentesis include:
Which of the following is safe to give to a pregnant women with deep venous thrombosis (DVT)?
Correct Answer B:
A deep vein thrombosis (DVT) is a blood clot that forms in a deep vein. The most common sites for a DVT during pregnancy and after birth are in a vein in the leg (especially the calf or thigh) or in the pelvis. Once it is determined that anti-coagulation is indicated, it should be initiated using subcutaneous low molecular weight heparin (LMWH), intravenous unfractionated heparin (UFH), or subcutaneous unfractionated heparin. Subcutaneous LMWH is preferred over IV UFH or SC UFH in most patients because it is easier to use and it appears to be more efficacious with a better safety profile. UFH (either IV or SC) is preferred over SC LMWH in patients who have severe renal failure. Warfarin is generally not used, particularly in the first trimester, because it may be teratogenic.
A 25-year-old woman who is pregnant with her third child comes to the office for a regular prenatal visit. Medical history shows that she developed deep vein thrombosis of the left calf in the 22nd week of her last pregnancy 2 years ago. She is now 26 weeks pregnant, and she complains of left calf tenderness during the examination. Deep vein thrombosis is confirmed by Doppler ultrasonography.
The most appropriate management is to:
The occurrence of deep venous thrombosis during pregnancy is of concern because 5-20% of patients will experience pulmonary embolism, a potential fatal complication. In the early stages of thrombosis, the clot may be loosely adherent to the vessel wall, and amenable to pharmacologic intervention.
The preferred agent is heparin. It is a potent inhibitor of thrombin, and thus prevents the conversion of fibrinogen to fibrin. Because of its large molecular size and negative charge, it does not cross the placenta, and does not appear in breast milk. The dosage of heparin is monitored by measuring the partial prothrombin time, which should be two to three times the control value. Intravenous administration of protamine sulfate counteracts the effects of heparin quickly on a milligram-for-milligram basis.
A 34-year-old white female at 32 weeks gestation develops a venous thromboembolism. Following 5 days of intravenous heparin in the hospital, which one of the following regimens would be most appropriate?
Heparin does not cross the placenta and is safe for the fetus, whereas coumarin derivatives can cause fetal bleeding and are teratogenic during weeks 6-12. Therefore, pregnant women with venous thromboembolism should receive intravenous heparin for 5 days, followed by adjusted-dose subcutaneous heparin every 12 hours until delivery. Increasingly, low-molecular-weight heparins are being used instead of unfractionated heparin because of ease of administration and the reduced need for coagulation monitoring. Intravenous heparin is not necessary after the patient leaves the hospital, and aspirin has not been shown to be beneficial.
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