A 23-year-old pregnant woman at 5 postmenstrual weeks took coumadin until about 3 days after her menses was due. She has monthly menses. A home pregnancy test was positive on the day she took coumadin. She takes coumadin because of a history of deep vein thrombosis and pulmonary embolism. She is concerned that the coumadin will cause birth defects.You tell her that the conceptus is most susceptible to teratogenesis at what stage of pregnancy?
Answer(s): D
The conceptus is remarkably resistant to the toxic and teratogenic effects of most drugs until about 2 postconceptual weeks (4 postmenstrual weeks). Although certain drugs may be toxic to oocytes, their effect will be to prevent conception or cause an early spontaneous abortion. The developing conceptus is not exposed to maternal toxins or teratogens until after implantation and establishment of a blood supply from mother to fetus. Even after implantation, the fetus is relatively resistant to teratogens for about 1 week. Organogenesis is complete by the end of the first trimester. Congenital abnormalities are, therefore, unlikely in the second and third trimesters.
A 23-year-old pregnant woman at 5 postmenstrual weeks took coumadin until about 3 days after her menses was due. She has monthly menses. A home pregnancy test was positive on the day she took coumadin. She takes coumadin because of a history of deep vein thrombosis and pulmonary embolism. She is concerned that the coumadin will cause birth defects.You advise this woman to do which of the following?
From the information in question 163, it is apparent that the fetus is relatively resistant to teratogenic effects of drugs until about 2 weeks after conception. A recommendation to abort the pregnancy cannot be made on medical probability, although the woman may choose this, because she does not wish to take any chance of having an affected child. Ultrasound is incapable of detecting anomalies until at least 1214 postmenstrual weeks. The fetal warfarin syndrome does not cause chromosomal abnormalities, and a genetic amniocentesis is not indicated. Vitamin K reverses the anticoagulant effects of coumadin but does not alter the risk that the fetus will develop anomalies.
A 23-year-old pregnant woman at 5 postmenstrual weeks took coumadin until about 3 days after her menses was due. She has monthly menses. A home pregnancy test was positive on the day she took coumadin. She takes coumadin because of a history of deep vein thrombosis and pulmonary embolism. She is concerned that the coumadin will cause birth defects. Which of the following is the treatment of choice during pregnancy for this woman?
Answer(s): B
Heparin is the drug of choice for anticoagulation in pregnancy. Little of it crosses the placenta, and it is not associated with congenital birth defects. Experience with low molecular weight heparin in pregnancy is increasing and appears to be safe for mother and fetus. In full therapeutic doses, low molecular weight heparin offers the advantage of less or no monitoring of its anticoagulant effect. Coumadin readily crosses the placenta and is associated with birth defects in 1525% of fetuses exposed throughout the first trimester. Aspirin is ineffective as an anticoagulant, although the risk of maternal or fetal bleeding (e.g., placental abruption, fetal intracranial bleeding) is increased. There is no clinical experience with TPA in pregnancy. Because pregnancy itself is a thrombogenic condition, anticoagulation throughout pregnancy is indicated. Vena caval filters offer no advantage over heparin and require an invasive procedure.
A 19-year-old primigravida at term has been completely dilated for 21/2 hours. The vertex is at 2 to 3 station, and the position is occiput posterior. She complains of exhaustion and is unable to push effectively to expel the fetus. She has an anthropoid pelvis. Which of the following is the most appropriate management to deliver the fetus?
Answer(s): C
The station of the vertex indicates that the fetal head is on the perineum. A cesarean section, either low transverse or classical, is inappropriate unless an operative vaginal delivery is unsuccessful. In women with an anthropoid pelvis, the transverse, interspinous diameter of the bony pelvis is narrow, and the anteroposterior diameter of the pelvis is relatively long. In this circumstance, a forceps rotation should not be done and delivery should be in the occiput posterior. The indication for forceps is maternal exhaustion; women with an anthropoid pelvis usually have a spontaneous vaginal delivery. In women with a gynecoid pelvis, the transverse and anteroposterior diameters are more equal, and rotation of the fetal head to occiput anterior would be an acceptable choice. Soft-tissue resistance to delivery is not great enough that an episiotomy will permit slight expulsive efforts by the mother to deliver the fetal head
A 22-year-old woman and her 24-year-old partner have been attempting to conceive for 12 months. They have sexual intercourse two to three times per week and use no contraception or coital lubricants. She has never been pregnant and her husband has fathered no pregnancies. She has no history to suggest damage to her Fallopian tubes and her menses occur at 28- to 31-day intervals. What is the probability of conception per ovulation in normally fertile couples?
Fecundability is the ability to achieve a pregnancy, and the rate per ovulation in couples with no impediment to fertility is approximately 2025%. This figure is reduced as the woman enters her early 30s, if sexual intercourse occurs fewer than one to two times per week, or if the couple use coital lubricants in the periovulatory part of her menstrual cycle. Using the 20% fecundability rate, 20 of 100 couples will achieve a pregnancy in the first menstrual cycle of effort. In the second cycle, 20% of the remaining 80 couples will achieve a pregnancy, that is 16 women. This is a cumulative pregnancy rate of 36%. Twenty percent of the remaining 64 women will conceive in the third cycle, approximately 13 women. The cumulative conception rate after three cycles is approximately 49%. Continuing this calculation, 9095% of normally fertile couples will achieve a pregnancy within 12 ovulations. Based on this calculation, infertility is defined as the inability to conceive after 12 ovulatory cycles.
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