If an abnormally high maternal serum alpha-fetoprotein level is found at 16-18 weeks gestation, the next step is:
Correct Answer A:
Screening maternal serum alpha-fetoprotein levels should be offered to patients at 16-18 weeks gestation to detect open neural tube defects. Abnormally high levels must be confirmed by immediate repeat measurement. The next step is level I ultrasonography to rule out other conditions which can result in elevated levels, such as multiple gestation, incorrect gestational age or fetal demise. More detailed level II ultrasonography and amniocentesis are then performed if the initial results are normal and confirm fetal age. An open neural tube defect is found within only 2%-3% of positive maternal serum tests. Therefore, recommendations for termination of the pregnancy should be made only after confirmation of a problem by ultrasonography and amniocentesis. The significance of alpha-fetoprotein levels after 22 weeks gestation is unknown. In addition, testing at 24 weeks would not allow adequate time for termination of an abnormal pregnancy by those patients who choose to do so.
An otherwise healthy 21-year-old primigravida comes to your office for a routine visit at 16 weeks gestation. She has had a normal pregnancy to date, and her only medication is a multivitamin with 0.4 mg folic acid. You order a maternal serum alpha-fetoprotein level. Adjusted for gestational age, maternal weight, and race, the results are significantly elevated.
Which one of the following would you now recommend?
Correct Answer D:
A 16-week visit is advised for all pregnant women to offer an alpha-fetoprotein (AFP) screening for neural tube defects and Down syndrome. An AFP level 2-5 times the median value for normal controls at the same gestational age is considered elevated. Approximately 5%-10% of patients who undergo AFP screening will have an elevated level, and most of these women will have normal fetuses. Fetal ultrasonography should be performed to detect multiple gestation, fetal demise, or fetal anomalies (neural tube defects, ventral abdominal wall defects, and urinary tract anomalies) as well as to confirm gestational age, as all of these factors are associated with elevated AFP levels. Amniocentesis is offered if the ultrasonography does not indicate the reason for the elevated AFP. Chorionic villus sampling is offered in the evaluation of suspected chromosomal anomalies as an adjunct to amniocentesis. Serum hCG would be indicated in the workup of suspected Down syndrome, where the AFP would be low, not elevated. The hCG level would be expected to be over 2-5 multiples of the mean (MoM) with Down syndrome.
In a normal pregnancy at 16 weeks’ gestation, which of the following has the highest alpha fetoprotein concentration?
Produced primarily in the fetal liver, alpha fetoprotein is the major oncotic protein in the fetus. It reaches a peak value in fetal serum at 12-14 weeks, at a level of about 3 mg/ml. The peak value in fetal amniotic fluid is around 40 ng/ml and occurs at or just after that in fetal serum. The maternal serum reaches its peak of 200 ng/ml at the end of the second trimester and begins to gradually decrease after 30 weeks. Thus, the concentration of AFP in the fetal serum is 10,000- fold greater than that in maternal serum.
A. The concentration of AFP in the amniotic fluid is less than that in fetal blood.
B. The concentration of AFP in the cerebrospinal fluid is less than that in fetal blood.
C. The concentration of AFP in the maternal serum is 10,000-fold less than that in fetal blood.
E. The concentration of AFP in the fetal urine is less than that of fetal blood. In cases of severe fetal nephritic syndrome, fetal urine will have a high AFP concentration, and the MSAFP will often be significantly elevated (sometimes well beyond that found with a neural tube defect).
In which of the following conditions would you not expect to find an elevated alpha-fetoprotein level during a routine screen done at 16 weeks gestation?
Alpha-fetoprotein is an excellent screening tool used during pregnancy to identify a fetus with a suspected neural tube defect if measured between 16-18 weeks gestation. All of the abnormalities listed above are forms of neural tube defects and therefore would be expected to have an elevated alpha-fetoprotein level, except for sub-arachnoid hemorrhage.
A 60-year-old female presents with 5 x 5 cm adnexal mass. After a workup she is diagnosed with ovarian cancer.
What is the most appropriate next step in management?
Ovarian cancer is often fatal because it is usually advanced when diagnosed. Symptoms are usually absent in early stage and nonspecific in advanced stage. Evaluation usually includes ultrasonography, CT or MRI, and measurement of tumor markers (eg, cancer antigen 125). Diagnosis is by histologic analysis. Staging is surgical.
Treatment requires hysterectomy, bilateral salpingo-oophorectomy, excision of as much involved tissue as possible, and, unless cancer is localized, chemotherapy.
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