A 20-year-old G2P1 patient comes to see you at 17 weeks gestational age to review the results of her triple test done 1 week ago. You tell the patient that her MSAFP level is 2.0 MOM (singkatan dari Maternal Serum Alfa Feto Protein. MOM itu satuannya-Multiple of the Median. Nilai normal: 0.5-2.0 keterangan lebih lanjut klik disini,-Dev). The patient’s obstetrical history consists of a term vaginal delivery 2 years ago without complications. Which of the following is correct advice for your patient regarding how to proceed next?
a. Explain to the patient that the blood test is diagnostic of a neural tube defect and she should consult with a pediatric neurosurgeon as soon as possible
b. Tell the patient that the blood test result is most likely a false-positive result and she should repeat the test at 20 weeks
c. Refer the patient for an ultrasound to confirm dates
d. Offer the patient immediate chorionic villus sampling to obtain a fetal karyotype
e. Recommend to the patient that she undergo a cordocentesis to measure fetal serum AFP levels
the answer is below…
The United States Medical Licensing Examination, or USMLE for short, is a three-part licensing examination that is required in order to receive a license to practice medicine within the United States.
The USMLE assesses a physician’s ability to apply knowledge, concepts, and principles, and to determine fundamental patient-centered skills that are important in health and disease and that constitute the basis of safe and effective patient care.Examination committees composed of medical educators and clinicians from across the United States and its territories prepare the examination materials each year.
This exam is designed by the Federation of State Medical Boards and the National Board of Medical Examiners to determine whether or not an individual understands and can apply the knowledge necessary to practice medicine safely and intelligently.
The USMLE is actually comprised of three different exams that are referred to as steps, which examine the individual’s knowledge of specific topics related to the field of medicine such as basic science, medical knowledge, medical skills, clinical science, and the application of all of these skills and areas of knowledge in the medical field.
All three steps of the USMLE include a series of computerized multiple-choice questions, but the format of the exam and the information covered in each multiple-choice section is different for each step of the USMLE. The USMLE Step II also has a clinical skills portion that examines an individual’s ability to work with real patients and the USMLE Step III has a computerized patient simulation portion in addition to the multiple-choice section of the exam. In order for an individual to receive a license to practice medicine, the individual must pass all three steps of the USMLE.
The correct answer is c; Refer the patient for an ultrasound to confirm dates.
The multiple marker screening test, also referred to as the expanded AFP test or triple screen, consists of maternal serum measurements of estriol, human chorionic gonadotropin, and a-fetoprotein. The multiple marker screening test is used to determine a pregnant patient’s risk of having a baby with aneuploidy and a neural tube defect. The AFP test has the greatest sensitivity when done between 16 and 18 weeks. A maternal serum AFP level that is greater than or equal to 2.0 to 2.5 MOM indicates an elevated risk for a neural tube defect and indicates that further workup and evaluation are needed. The first step when an elevated serum AFP result is obtained is to have the patient undergo an ultrasound to verify that the gestational age of the pregnancy is correct. The sonogram can also identify a fetal death in utero, multiple gestation, or a neural tube or abdominal defect, which could all explain the elevated AFP level. A repeat serum AFP test can be done, because at a level of 2.0 MOM there is some overlap between normal and affected pregnancies. The repeat test should be done as soon as possible; waiting until 20 weeks decreases the sensitivity of the test and wastes valuable time in the workup. An amniocentesis is recommended if a neural tube defect is suspected in order to measure amniotic fluid levels of AFP and therefore confirm the findings of the maternal serum AFP. The physician would not immediately refer the patient for a chorionic villus sampling because this procedure obtains placental tissue for fetal karyotyping and does not add to information regarding the presence of a neural tube defect. A cordocentesis, or percutaneous umbilical cord blood sampling (PUBS), is a procedure whereby the umbilical vein is punctured under ultrasonic guidance and a fetal blood sample is obtained. Usually a PUBS is performed when rapid fetal karyotyping must be done, such as in a situation where severe growth restriction exists. PUBS is most commonly used in situations where fetal hydrops exists to obtain information regarding fetal platelet counts and fetal hematocrits.