After an initial pregnancy resulted in a spontaneous loss in the first trimester, your patient is concerned about the possibility of this recurring.
Which of the following is the most appropriate answer regarding the risk of recurrence after one miscarriage?
An initial spontaneous abortion, regardless of the karyotype or gender of the child, does not change the risk of recurrence in a future pregnancy. The rate is commonly quoted as 15% of all known pregnancies.
A 24-year-old woman presents with a history of one first-trimester spontaneous abortion.
Which of the following is the single most common specific chromosome abnormality associated with first trimester miscarriage?
Chromosomal abnormalities are found in approximately 50% of spontaneous abortions in the first trimester. Chromosome abnormalities become less common in advancing pregnancy, and are found in approximately one-third of second trimester losses and 5% of third trimester losses. Autosomal trisomy is the most common group of chromosomal anomalies leading to first trimester miscarriage. However, 45 X (Turner syndrome) is the most common single abnormality found.
A 29-year-old G3P0 presents to your office for preconception counseling. All of her pregnancies were lost in the first trimester. She has no significant past medical or surgical history.
She should be counseled that without evaluation and treatment her chance of having a live birth is which of the following?
Miscarriage risk rises with the number of prior spontaneous abortions. Without treatment, the live birth rate approaches 50%. With treatment, successful pregnancy rates of 70% to 85% are possible in a patient with a diagnosis of habitual abortion, depending on the underlying cause. When cervical incompetence is present and a cerclage is placed, success rates can approach 90%.
A 26-year-old G3P0030 has had three consecutive spontaneous abortions in the first trimester.
As part of an evaluation for this problem, which of the following tests is most appropriate in the evaluation of this patient?
A major cause of spontaneous abortions in the first trimester is chromosomal abnormalities. Parental chromosome anomalies account for 2% to 4% of recurrent losses; therefore, karyotype evaluation of the parents is an important part of the evaluation. The causes of losses in the second trimester are more likely to be uterine or environmental in origin. Patients should also be screened for thyroid function, diabetes mellitus, and collagen vascular disorders. There is also a correlation between patients with a positive lupus anticoagulant and recurrent miscarriages. For recurrent second-trimester losses, a hysterosalpingogram should be ordered to rule out uterine structural abnormalities, such as bicornuate uterus, septate uterus, or unicornuate uterus. Endometrial biopsy is performed to rule out an insufficiency of the luteal phase or evidence of chronic endometritis. A postcoital test may be useful during an infertility evaluation for couples who cannot conceive, but does not address postconception losses. Measuring the cervical length by ultrasonography is helpful in the management of patients with recurrent second-trimester losses caused by cervical incompetence.
A 30-year-old G1P0 at 8 weeks’ gestation presents for her first prenatal visit. She has no significant past medical or surgical history. A 29-year-old friend of hers just had a baby with Down syndrome and she is concerned about her risk of having a baby with the same problem. The patient reports no family history of genetic disorders or birth defects.
You should tell her that she has an increased risk of having a baby with Down syndrome in which of the following circumstances?
The answer is b. The risk of aneuploidy is increased with multiple miscarriages not attributable to other causes such as endocrine abnormalities or cervical incompetence. Paternal age does not contribute significantly to aneuploidy until around age 55, and most risks of paternal age are for point mutations. A 45 X karyotype results from loss of chromosome material and does not involve increased risks for nondisjunctional errors. Similarly, induced ovulation does not result in increased nondisjunction, and hypermodel conceptions (triploidy) do not increase risk for future pregnancies.
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