Biochemical

Normal variations in laboratory values occur during pregnancy (Table 1). The gravid patient experiences a physiologic anemia secondary to an increase in plasma volume, which exceeds the increase in red blood cell mass. This physiologic anemia of pregnancy reaches its nadir at 30-34 weeks' gestation. The pregnant state also causes a mild dilutional hypoalbuminemia with albumin levels at term being 25% lower than nonpregnant values (20). Alkaline phosphatase is elevated secondary to the effects of estrogen although other liver function tests remain normal. Alkaline phosphatase normally rises during the third trimester reaching values of 2-4 times greater than seen in nonpregnant patients. Leukocytosis is a normal result of pregnancy. During the first and second trimesters, white blood cell counts normally range from 6000 to 16,000 cells/mm3 (34). Furthermore, marked changes in adrenocortical function are associated with pregnancy, resulting in increased levels of aldosterone, cortisol, and free cortisol (20).

Pregnant sheep models have been used to demonstrate that not only periods of severe hypercarbia (PaCO2 >60 mmHg) but also severe hypocapnia (PaCO2 <29 mmHg) reduce uterine blood flow leading to fetal distress. These changes have not been documented during laparoscopic surgery with appropriate anesthetic monitoring and maintenance of normal maternal pH.

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