A nurse is assessing a patient who reports nausea and vomiting at 8 weeks gestation. What is the most likely physiological cause of this symptom?
Increased progesterone levels suppressing uterine contractions
Elevated hCG levels stimulating the chemoreceptor trigger zone
Increased blood volume causing gastric irritation
Uterine pressure on the stomach reducing gastric capacity
The Correct Answer is B
Pregnancy is identified through presumptive, probable, and positive signs, categorized by specificity. Presumptive signs are subjective and experienced by the woman. Probable signs are objective, observed by providers. Positive signs are definitive evidence of a fetus. Nausea and vomiting, amenorrhea, breast changes, and quickening are presumptive. Positive signs include fetal heart tones, visualization via ultrasound, and fetal movement felt by the examiner. Human chorionic gonadotropin (hCG) becomes detectable around day 8 post-fertilization and peaks between 60–70 days, but a positive test alone is not diagnostic.
Rationale for correct answers
2. Elevated hCG levels are strongly associated with nausea and vomiting in early pregnancy. hCG peaks between 8–11 weeks and directly stimulates the chemoreceptor trigger zone in the brainstem, inducing nausea. This explains the timing and severity of symptoms during the first trimester.
Rationale for incorrect answers
1. Increased progesterone suppresses uterine contractions by relaxing smooth muscle but is not the primary cause of nausea and vomiting. Its main effects are maintaining the endometrial lining and reducing uterine irritability, not stimulating the vomiting center.
3. Increased blood volume begins rising early in pregnancy but peaks around 32–34 weeks. It does not directly irritate the gastric lining nor explain first-trimester nausea, which is hormonally mediated.
4. Uterine pressure on the stomach becomes relevant later in pregnancy, particularly in the third trimester, leading to reflux or reduced gastric capacity—not nausea at 8 weeks.
Take home points
• Nausea and vomiting at 8 weeks are primarily due to elevated hCG stimulating the chemoreceptor trigger zone.
• Progesterone relaxes smooth muscle but is not the main cause of nausea.
• Blood volume increases later and does not directly cause early pregnancy nausea.
• Uterine compression of the stomach causes late pregnancy symptoms, not first-trimester nausea.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is ["A","C","E"]
Explanation
Pregnancy is identified through presumptive, probable, and positive signs, categorized by specificity. Presumptive signsare subjectiveand experienced only by the pregnant individual. Probable signsare objective, observable by clinicians, but not definitive. Positive signsare conclusiveand confirm the presence of a fetus. Presumptive signsinclude nausea and vomiting, amenorrhea, breast tenderness, fatigue, and quickening(first fetal movement felt by the mother, usually at 16–20 weeks). These signs can result from causes other than pregnancy, thus are not diagnostic.
Rationale for correct answers
1.Amenorrhea is a presumptive sign because it is a subjective experience commonly caused by pregnancy. It occurs due to suppression of the hypothalamic–pituitary–ovarian axis by rising hCG and progesterone.
3.Nausea and vomiting are presumptive signs caused by rising hCG levels stimulating the chemoreceptor trigger zone. These symptoms are subjective and occur in other conditions, making them non-definitive.
5.Quickening refers to the woman’s first perception of fetal movement, usually between 16–20 weeks. It is a subjective experience and can be confused with gastrointestinal activity, classifying it as presumptive.
Rationale for incorrect answers
2.Fetal heart sounds are a positive sign. They provide direct evidence of fetal life and are detected by Doppler around 10–12 weeks. This confirms pregnancy beyond doubt.
4.Uterine enlargement is a probable sign. It is an objective finding noted during bimanual examination or ultrasound but may also result from tumors or fibroids. It suggests pregnancy but is not conclusive without positive signs.
Take home points
• Presumptive signs are subjective and felt only by the pregnant individual.
• Amenorrhea, nausea, and quickening are classic presumptive signs.
• Fetal heart tones and uterine growth are not presumptive—they are positive and probable, respectively.
• Presumptive signs must be confirmed with objective or positive findings.
Correct Answer is C
Explanation
Pregnancy is identified through presumptive, probable, and positive signs, categorized by specificity. Presumptive signsare subjectiveand experienced by the woman. Probable signsare objective, observed by providers. Positive signsare definitiveevidence of a fetus. Nausea and vomiting, amenorrhea, breast changes, and quickeningare presumptive. Positive signs include fetal heart tones, visualization via ultrasound, and fetal movement felt by the examiner. Human chorionic gonadotropin (hCG) becomes detectable around day 8 post-fertilization and peaks between 60–70 days, but a positive test alone is not diagnostic.
Rationale for correct answers
3.Nausea and vomiting are classic presumptive signs of pregnancy, resulting from elevated estrogen and hCG levels. These symptoms are common in early pregnancy but are subjective and not exclusive to pregnancy.
Rationale for incorrect answers
1.A positive pregnancy test is a probable sign. It detects hCG, which rises after implantation. However, elevated hCG can also occur in trophoblastic disease or recent miscarriage, making it insufficient alone for diagnosis.
2.Auscultation of fetal heart tones is a positive sign. Fetal heart sounds are independent of the mother’s and confirm fetal presence. They can be detected by Doppler from 10–12 weeks of gestation.
4.Visualization of the fetus by ultrasound is a positive sign. Seeing the embryo or fetus with cardiac activity confirms intrauterine pregnancy. Cardiac motion can be seen by transvaginal ultrasound at approximately 5–6 weeks.
Take home points
• Nausea and vomiting are presumptive signs because they are subjective experiences.
• Positive pregnancy tests are probable signs due to the possibility of false positives.
• Fetal heart tones and ultrasound visualization are definitive indicators of pregnancy.
• Presumptive signs alone cannot confirm pregnancy; positive signs are required for confirmation.
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