A pregnant person is exposed to a teratogen at 16 weeks pregnant.
Which organ or feature of the fetus is sensitive to a functional defect or abnormalities at that time?
Neural Tube Defects.
Ears.
Cleft palate.
Heart.
The Correct Answer is C
Choice A rationale
Neural tube defects, such as spina bifida or anencephaly, occur during primary neurulation, which is a process primarily completed in the very early embryonic period, specifically between 3 and 4 weeks of gestation. By 16 weeks, the neural tube is closed and this feature is past its most sensitive period for teratogenesis.
Choice B rationale
The most critical period for the development of the external ears is during the embryonic period, weeks 4 through 9 of gestation. While development continues, the major structural formation is complete before 16 weeks, making it less susceptible to major structural defects at this later gestational age.
Choice C rationale
The palate shelves fuse at approximately 10 to 12 weeks gestation, but the full consolidation and final development of the hard and soft palate structures continues. This structure remains sensitive to disruption and functional abnormalities, such as cleft palate, well into the late first and early second trimesters, around 16 weeks.
Choice D rationale
Major structural development of the heart, including septation and formation of the great vessels, is most sensitive to teratogens between weeks 3 and 8 of gestation. By 16 weeks, the heart structure is largely complete, and its vulnerability shifts from structural defects to primarily growth restriction or functional issues.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["A","E"]
Explanation
Choice A rationale
Auscultation of the fetal heartbeat by a trained professional, typically with a Doppler device by 10 to 12 weeks of gestation, is a positive and definitive sign of pregnancy. This is an objective sign that verifies the presence of a living fetus and is completely unique to the state of being pregnant.
Choice B rationale
Verification of fetal movement, though a probable sign when felt by the examiner, is not considered a positive sign because involuntary muscle contractions, peristalsis, or movement of gas can be mistaken for fetal movement. Positive signs are objective, definitive proof of a fetus.
Choice C rationale
A positive human chorionic gonadotropin (hCG) test is a highly reliable probable sign of pregnancy, as this hormone is produced by the trophoblast. However, elevated hCG can rarely be caused by non-pregnant conditions like certain tumors, thus it is not considered a definitive, positive sign.
Choice D rationale
Palpating the uterine fundus to estimate uterine size is a probable sign of pregnancy. While suggestive of an enlarging uterus, it is subjective and can be mimicked by pelvic masses or uterine tumors like leiomyomas, failing to provide irrefutable evidence of a pregnancy.
Choice E rationale
Visualization of the fetus or embryo via ultrasound is the most conclusive and positive diagnostic sign of pregnancy. Seeing the gestational sac, fetal pole, or fetal structures unequivocally confirms the presence of an intrauterine gestation and is unique to pregnancy.
Correct Answer is D
Explanation
Choice A rationale
Continued bloody show refers to the mucous plug mixed with a small amount of blood, which is a normal finding during labor as the cervix softens, effaces, and dilates. While the amount of bloody show is monitored, it is not the most immediate or critical concern compared to a pathway for bacterial ascent, especially in a GBS-positive client.
Choice B rationale
Cervical dilation of 4 cm indicates the client is in the active phase of the first stage of labor. Although the rate of dilation is important, a GBS-positive client at 4 cm is generally expected to progress, and this finding does not represent the highest risk compared to potential exposure from membrane rupture.
Choice C rationale
Contractions every 4 minutes indicate effective uterine activity for progression of labor, which is an expected physiological process. Monitoring contraction frequency and intensity is standard, but contractions themselves do not pose the greatest risk factor for a GBS-positive client compared to compromised integrity of the amniotic barrier.
Choice D rationale
Spontaneous rupture of membranes (SROM) 3 hours ago in a GBS-positive client significantly increases the risk of ascending infection, potentially leading to chorioamnionitis in the mother and neonatal sepsis. The GBS organism can colonize the birth canal, and once the barrier is broken for an extended period, the risk becomes acute, requiring prompt antibiotic prophylaxis.
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