Normal Pregnancy 1 Flashcards
Explain the maternal physiologic chanegs in pregnancy as a basis of how that can affect disease presentation.
What are the changes to the uterus during pregnancy?
- Total volume of urine contents at term range from 5-20L (10 mL when not pregnant)
- Uterine weight about 1100g (vs. 70g)
- Unergoes hypertrophy due to estrogen and maybe progesterone
- Progressive increase in uteroplacental blood flow as gestation advances
What are the changes to the cervix during pregnancy?
- Softens and undergoes cyanosis early on
-
Hypertrophy and hyperplasia of glands
- eversion of proliferating columnar endocervical glands
- Production of tenacious mucus rich in immunoglobulins which act as a protective barrier against normal vaginal bacteria
What are the changes to the vagina during pregnancy?
- Chadwick sign - increased vaginal vascularity that accounts for bluish/purplish color during pregnancy
- Increase in mucosal thickness
- Loosening of connective tissue
- Hypertrophy of smooth muscle cells
What are the changes to the ovaries during pregnancy?
- Corpus luteum present and functional until 7 weeks gestation
- Vascular pedicle increases from 0.6 cm outside of pregnancy to 2.6 cm at term
- Decidual reaction
- Luteoma -> exaggerated luteinization of ovary
- May result in maternal virilization but without effect on fetus
What are the changes to the theca lutein cyst during pregnancy?
- Exaggerated physiological follicle stimulation (hyperreactio luteinalis)
- Usually bilateral cystic ovaries
- Associated with high hCG levels (multiple gestation, GTD)
- Maternal virilization occurs in 25% of patients with theca lutein cysts
What are the cardiac changes during pregnancy?
-
Elevation of diaphragm results in displacement of heart up and left
- results in enlargement of cardiac silhouette on CXR
- ~50% increase in circulating blood volume
- ~15% increase in resting heart rate
- ~20-50% increase in CO
- **Increased heart rate **and decreased preload as a result
What are the vascular changes during pregnancy?
-
BP similar to pre-pregnant levels in first tirmester
- Initial decrease in SVR
-
BP nadirs in second trimester
- systolic decreases 5-10 mmHg
- diastolic decreases 10-15 mmHg
-
BP increases back to baseline values in third trimester
- Impairment of venous return by mechanical uterin obstruction overall increases SVR
What are the respiratory changes during pregnancy?
- Diaphragm elevates, subcostal angle increases, and thoracic circumference increases
- No change in respiratory rate
- 40% increase in tidal volume
- 20% decrease in residual volume and functional residual capacity
-
Dyspnea of pregnancy
- Results from increased TV that lowers maternal PCO2, which is required for proper diffusion of CO2 from fetus to mother
- Decreased PCO2 is compensated by increase excretion of bicarbonate
What are the gastrointestinal changes during pregnancy?
- Displacement of stomach and intestines by enlarging uterus
- Gastric emptying time unchanged during pregnancy, but increases substantially during labor (especially after administration of analgesics)
- Liver itself has minimal changes except increased blood flow
- Certain hepatic lab tests “abnormal” but related to pregnancy changes and not pathology
- Alk phos
- Albumin
What are the renal/urinary changes during pregnancy?
- Slight increase in kidney size
- GFR increases by up to 50% by mid-pregnancy, with even greater increases in RPF
- Serum Cr decreases normally in pregnancy
- Uterine displacement of ureters results in ureteral dilatation
- Increased bladder pressure but with compensation by elongation of urethra, which increases intraurethral pressure and maintains continence
What is the purpose of hypervolemia in pregnancy?
- Meets metabolic demands of the enlarged uterus and its hypertrophied vascular system
- Provides nutrients to support rapidly growing placenta/fetus
- Protects mother (and thus fetus) against deleterious effects of impaired venous return in supine and erect positions
- Protects mother against adverse effects of blood loss associated with parturition
What are the changes to erythrocytes/hemoglobin in pregnancy?
- Erythroid hyperplasia occurs and slight increase in reticulocyte count (not abnormally high)
- Erythrocyte volume increases by about 450 mL by the end of pregnancy
- Increase in erythrocytes not as great as increase in blood volume à slight decrease in Hb and Hct in pregnancy (Hb < 11.0 g/dL considered anemic)
What are the iron requirements of pregnancy?
1000 mg Fe required for pregnancy, with about 1/3 transferred to fetus and placenta
How do leukocytes change in pregnancy?
- Varies considerably in pregnancy, but not abnormal for slight leukocytosis to be present
-
Distribution of cell types altered in pregnancy
- ↑ granulocytes and CD8 lymphocytes
- ↓ CD4 lymphocytes and monocytes
What are the changes to coagulation/firbrinolysis during pregnancy?
- Both augmented but remain balanced to maintain homeostasis
- All clotting factors increase with exception of factor XI and factor XIII
- Protein S decreases in pregnancy, as does activated protein C
- tPA increases throughout pregnancy
- Minimal decrease in platelet count in pregnancy (attributed to hypervolemia)