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At what point does ultrasound scan dating become less accurate?
- After 20 weeks gestational age. It can be used later, keeping in mind its limitations.
- Biologic variation in size increases as gestation advances
What are the uses of ultrasound scanning in pregnancy?
- 1. To confirm and intrauterine pregnancy (if it is suspected to be ectopic)
- 2. To confirm presence of fetal heartbeat in a patient with hx of miscarriage.
- 3. To dx multiple pregnancy
- 4. To estimate gestational age
- 5. To screen for fetal structural anomalies
At what week of gestation should one worry if fetal heart tones can't be auscultated?
11 weeks gestational age. Do an ultrasound eval to document viable intrauterine pregnancy.
When can electronic doppler detect fetal heart tones?
As early as 8 weeks gestational age
When is plasma hCG used?
- To aid in dx of ectopic pregnancy
- Monitor trophoblastic tumors
- screen for fetal abnormalities
- serial levels checked to rule out spontaneous abortion (<10weeks)
What is the preferred method to recognize a normal pregnancy?
- Urine hCG!
- First morning specimens most accurate
- Assays detecting 25 mU/mL recognize pregnancy with 95% sensitivity by 1 week after first missed menstrual period
- False negatives may occur if: test is performed too early, urine is very dilute
- False positives: proteinuria (confirm with plasma hCG), UTI
When do blood levels of hCG become detectable?
8-10 days after fertilization (3-3.5 weeks after the LMP)
By how much should plasma hCG levels increase every 48 hours prior to 9-10 weeks?
What conditions, other than pregnancy, produce detectable hCG?
- Hydatidiform mole
- Other germ cell tumors
- Ectopically producing breast cancers and large cell carcinoma of lung
To what hormone is hCG similar in structure and function?
luteinizing hormone (beta subunits are similar in both hormones)
What should the fundal height be at 12, 15, 20, 28, 32, 36 and 40 weeks?
- 12: barely palpable above pubic symphysis
- 15: midpoint b/w pubic symphysis and umbilicus
- 20: at umbilicus
- 28: 6 cm above umbilicus
- 32: 6 cm below xyphoid
- 36: 2cm below xyphoid
- 40: 4 cm below xyphoid
What is chadwick's sign?
bluish discoloration of the vagina and cervix, due to congestion of pelvic vasculature.
What is hyperemesis gravidarum?
Frequent vomiting that typically occurs early in pregnancy. When severe it can result in weight loss, dehydration, acidosis (from starvation), alkalosis (from loss of HCl in vomitus), and hypokalemia.
What percent of women experience nausea and/or vomiting in pregnancy and at what gestational age?
70-85% of women most notably at 2-12 weeks, and typically in the AM
What may lead some women to fail to recognize their pregnancy early on?
Some women experience vaginal bleeding early in pregnancy.