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We calculated the amniotic fluid indexes (AFIs) of 310 women on 459 occasions. Normative data were analyzed and compared with data in several high-risk groups. In the normal gestations there was a progressive increase in AFI with advancing gestation until 32 weeks, after which there was a decline. The mean AFIs in abnormal gestations varied with the clinical diagnoses. These values were compared to those obtained by assessing amniotic fluid volume (AFV), that is a pocket more than 2 cm. There were 51 patients with abnormal AFVs. Forty-two had decreased fluid, six also had decreased AFIs; nine had increased AFVs and five (all with diabetes) also had increased AFIs. Thus, AFIs in normal pregnancies showed an orderly pattern of change with gestational age, and there was no accurate correlation between AFI and AFV. Thus, using AFV alone may lead to false interpretations of amniotic fluid status.

Chorioamnionitis during pregnancy is a common diagnostic dilemma for the obstetrician. Fast and accurate diagnosis poses the most significant problem. Since leukocytes are known to be released in response to infections, examination of amniotic fluid for their presence is an important part of the evaluation for chorioamnionitis. These neutrophils contain several esterases that are not present in serum, urine, or vaginal secretions. The esterases are not influenced by bacteria or by commonly used drugs. We have previously described the reliability of leukocyte esterase (LE) activity for the detection of chorioamnionitis in term pregnancies uncomplicated by other diseases. A prospective study was performed to assess the presence or absence of LE activity to establish normal values in amniotic fluid at various gestational ages prior to term before its use as a possible predictor for chorioamnionitis. Sterile amniotic fluid specimens were obtained from 13 patients undergoing second trimester genetic amniocentesis (with gestational ages varying from 15 to 19 weeks) and from 11 patients with a wide variety of medical problems, undergoing amniocentesis for Rh sensitization or lung maturation studies (with gestational ages ranging from 25 to 27 weeks). All patients with ruptured membranes or preterm labor were excluded. Each amniotic fluid sample was divided into two parts, one of which was transported to the laboratory for aerobic and anaerobic cultures and the other used for LE activity detection as measured by dipstick. The LE results were retrospectively compared with the results of the cultures. LE activity was always found to be negative when the culture results were negative. negative.(ABSTRACT TRUNCATED AT 250 WORDS)