Normal Pregnancy from Fertilization to Labor Flashcards
Describe the main events of fertilization
Fertilization between a haploid sperm and a haploid ova occurs in the ampulla of the fallopian tubes most commonly and is marked by:-completion of meiosis II by the ova-fusion of the nuclei to produce a diploid embryo-thickening of the zona pellucida to make it impenetrable
What happens to the embryo after fertilization on day 0?
There are rapid mitotic divisions that produce a 4 cell embryo by 24 hrs, an 8 cell embryo by 72 hrs, and a morula by 4 days,which enters the uterus and cavitates to producea blastocyst by 5 days
Describe the composition of a blastocyst
Once the morula cavitates to the form the blastocyst, an inner mass cell appears (to be the fetus), surrounded by an outer layer of trophoblast cells (destined to be the placenta)
When does implantation occur?
Probably day 8-9 from fertilization (although the embryo actually enters the uterus as a morula around days 5-6 and bounces around until it finds the right spot)
What is decidualization?
This is the process of progesterone from the corpus luteum preparing the endometrium for implantation by making it nutrient (glycogen and lipid) rich
How does implantation occur?
Trophoblastic cells invade the decidua. An important note to make is that the endometrium will actually re-develop around the entire embryo after it has invaded so that it can supply the entire structure with nutrients
When does hCG begin to be produced by trophoblastic cells?
only AFTER implantation (when this happens, a pregnancy can be detected via hCG levels on a BLOOD (not urine yet) test)
Normal gestation is calculated from when?
the first day of the last menstrual period (LMP)- b/c its easier to establish than the date of conceptionNOTE: this assumes a 28 day cycle no matter what actuality is
What is EDD?
Estimated date of delivery of estimated ‘due date’NOTE: Never confine a women to bedrest near the end of pregnancy (as was the old practice) due to risk of TE
What is a normal gestation?
40 +- 2 weeks (from the first day of the last menstrual period) or ‘40 weeks gestational age’
How is EDD calculated?
EDD is calculated by counting back 3 months from LMP and adding 7 daysEx: First day of LMP is May 10. EDD is February 17
What is the timeframe of the trimesters of pregnancy?
First: 0-14 weeksSecond: 14-28 weeksThird: 28-40 weeks
What is a ‘fetus’?
This is the term for a developing child during gestation, regardless of gestational age
When does organogenesis occur?
2-8 weeks gestation (fromfertilization)
What is abortion defined as?
The loss of pregnancy less than 20 weeks or less than 500 gm
What fetuses have a chance of viability?
anything 23+ weeks ofgestation. You would not put a pt. through a C-section if less than 23 weeks
What is preterm? Late term? Postterm?
Preterm- less than 37 weeksLate term- 41+ weeks gestationPostterm- 42+ weeks gestation (associated with AEs if they arent born soon during this period)
What is a gravid pt? Parity?
A gravid pt. is currently pregnant before while a parity pt. has had a baby before (can be either dead OR alive at birth)
Describe a G3P1011 pt.
Pregnant now (has been pregnant 3 times), one term birth, no preterm births, one abortion (could be spontanoeus OR induced), and one living child
What are some indications that pregnancy may be occurring?
Missed menses, followed by morning nausea and vomiting (typically worse in the first trimester), breast tenderness
When might a mother first feel a child move during gestation?
Typically week 18 for primigravida and week 16 for G2 or greater
When can urine tests detect pregnancy via hCG levels?
usually around 5-6 weeks GESTATIONS (from LMP), urine can detect the 25mIU/ml level needed to test positive
When can blood serumtests detect pregnancy via hCG levels?
usually at 3 weeks gestation serum tests can detect the 5 mIU/ml needed to test positive
How should hCG levels behave in early pregnancy?
Levels should double every 48 hrs in early pregnancy and peak around 10-12 weeks
How would a pregnancy present upon physical exam of the femal repro tract?
The uterus may present as soft by 6-7 weeks gestation, and produce a bluish hue from blood engorgement and enlarge around weeks 7-8.
When can fetal heart tones be heard first using a battery operated Doppler?
10 weeks gestation
T or F. The earlier an ultrasound is performed in pregnancy, the more accurate for dating
T.
YS= yolk sac; FP= fetal pole; halo=enlarged endometriumtransvaginal ultrasound picks up these images much faster than abdominal ultrasounds
What are some things that should addressed at the first prenatal visit?
Mainly you want to determine the risk for daverse maternal and fetal outcomes. Can do this via:-Questionnaire or face-to-faceAlso want to determine date of LMP and if contraception was being used then or not, if meds were used (teratogenic exposure),-previous preg, med, infection, or surgical Hx
What other things should be done at an initial prenatal visit?
complete phsyical exam and labsultrasound should be planned
What labs should be done at a first prenatal visit?
some tests are routine such as a CBC, and others are done to ensure maternal and fetal well-being and the fetal well-being
T or F. HIV is mandatory at the initial prenatal screening
F. Other infectious diseases are, but HIV is considered an opt-in (advise pt. to do)Performed during the first visit and review during the second
What are the routine labs done at an initial prenatal visit?
-CBC looking for anemia and thrombocytopenia-urine culture looking for bacteruria to prevent pyelonephritis (10^5+/ml)-blood group, RH, and Ab screens-Infectious diseases (syphillis, Hep B/C, chlamydia and gonorrhea and HIV in an opt-in)
What are the optional labs that should be presented to a pt. during an initial prenatal care visit?
-HIV-Pap smear dependent on age and guidelines-genetic screening including chromosomal abnromalities, carriership of single-gene disorders (including SCD), cystic fibrosis, SMA type i, and hemoglobinopathies
What is the big problem with RH status?
When the mother is RH- (d) and the fetus is RH+ (due to the father being RH+), the mother mounts an immune response and produced anti-D Abs. Fetal cells invariably get into maternal circulation during pregnancy.These anti-D Abs are IgG and thus can transfer through the placenta into the fetal circulation (aka alloimmunization) and cause lysis of the fetal RBCs (either intra or extravascular lysis in the spleen, liver, and bone marrow). The fetus then experiences anemia in utero
What is the result of the anemia in the fetus?
High-output cardiac failure, and eventually signs of failure will be seen on ultrasound including edema (aka hydrops), fetal tachycardia, and potentially fetal death
What is the tx if hydrops fetalis occurs?
Fetal anemia can be diagnosed before signs of the CHF show on ultrasound and can be addressed either via intrauterine transfusion or early delivery followed by postpartum newborn transfusion
What vitamins should a pt. be one prior to pregnancy?
folic acidOnce pregnant, pts. should typically receive iron and mineral supplements and be advised to increase fluids, avoid sushi, and improve diet
What are the main uses of ultrasound at different points during a pregnancy?
Early in pregnancy ultrasound is best used for dating, while ultrasound at 18-20 weeks can be used to detect birth defects (heart, septal, limbs, digits, fracial structures, and sex of the fetus)Additional ultrasound should be used for indications- uterus small, large, or other concerns
What major screenings should be done at 28 weeks gestation?
-Maternal DM check by drawing blood one hour after drinking Glucola (50gm load of glucose)-Administration of Rhogam if the mother is RH negative (Ab to D antigen)
What major screenings should be done at 36weeks gestation?
Repeat STI screening-recommended for high risk communities by the CD (if pt. has a previous Hx of positive screen for HIV, Hep B/C, RPR, GC, or chlamydia)-Culture for GBS
What should be done if the mother is positive for GBS at 36 weeks?
treat during labor with penicillin to prevent neonatal transmission
How often should a pregnant woman visit the OB?
Every 4 weeks from initial visit to 28 weeks gestation thenevery 2 weeks from 28-36 weeks, thenevery week past 36 weeks
Prostaglandins do induce labor
What are the phases of labor?
Latent and active
What is the latent phase of labor?
This phase occurs during pregnancy from ‘not in labor’ to when contractions begin and become regular and painful enough to cause cervical dilation up to 4cm.NOTE: This may last up to 18 hrs in a primigravida, and may be much more rapid in multigravidas
What is active phase of labor?
This is the time from when the cervix is dilted to 4+ cm until birth and is marked by more frequent, intense contractions.NOTE: Cervical dilation should occur at a rate of about 0.8cm/hr in a primigravida, and faster at 1.3cm/hr in a multiparous pt.
What is cervical effacement?
thinning of the cervix during labor
In the first stage, the mother cannot do anything to increase/decrease contractions until complete dilation of the cervix. However, the mother IS voluntarily responsible for the second stage
What are the cardinal movements?
- Descent of the vertex into the pelvis2. Flexion of the fetal head3. Internal rotation4. Extensionof the fetal head as it crosses the maternal perineum5. External rotation
