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Transcapillary forces in normal pregnant women
Acta Medica Scandinavica. Supplementum
|January 1, 1985
Summary
In late pregnancy, lower fluid pressure (COP) in interstitial fluid helps prevent edema. This mechanism is less effective in the third trimester, explaining why many pregnant women experience swelling.
Area of Science:
- Physiology
- Obstetrics
Background:
- Pregnancy involves significant physiological changes affecting fluid balance.
- Edema is common in late pregnancy, but its exact mechanisms are not fully understood.
Purpose of the Study:
- To investigate changes in plasma and interstitial fluid colloid osmotic pressure (COP) and interstitial fluid hydrostatic pressure (Pi) during normal pregnancy.
- To elucidate the role of these pressures in edema formation during late pregnancy.
Main Methods:
- Measurements of plasma and interstitial fluid COP and interstitial fluid hydrostatic pressure (Pi) were performed in 10 normal pregnant women.
- The 'wick' technique was used for interstitial fluid COP, and the 'wick-in-needle' technique for Pi.
Main Results:
- Colloid osmotic pressure (COP) was significantly lower in both plasma and interstitial fluid in the third trimester compared to the first trimester.
- The reduction in COP was more pronounced in the interstitial fluid than in plasma.
- Interstitial fluid hydrostatic pressure (Pi) showed only minor changes.
Conclusions:
- Reduced interstitial fluid COP is a key mechanism for preventing local edema in pregnancy.
- This compensatory mechanism may be compromised in late pregnancy due to a more significant drop in interstitial fluid COP.
- The findings suggest a reduced safety margin against edema, potentially explaining its high prevalence in normal pregnancy.