A rapid visual test for predicting fetal lung maturity

A rapid bedside test has been devised that enables an untrained observer to predict (p less than 0.001) when amniotic fluid will be greater than or equal to 0.15 at an optical density of 650 nm, lecithin/sphingomyelin ratio will be greater than or equal to 2.0, or when phosphatidylglycerol will be present. By a visual comparison of the turbidity of unspun amniotic fluid against positive (mature) or negative (immature) controls, technicians and resident physicians who had had no special training were able to classify correctly 87.2% (82/94) of unknown amniotic fluid samples. The sensitivity of the new test is 90.8% (58/65); the specificity is 70.3% (23/29). Thus, when more sophisticated methods are not readily available, we believe that this easily performed and accurate test can provide supplemental or preliminary data for patient management. In remote geographic areas our method could serve as the primary source of information about fetal lung maturity.

Antimicrobial activity of amniotic fluid against Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum

Amniotic fluids obtained by amniocentesis at 16 weeks to term were examined for the presence of Chlamydia trachomatis, Mycoplasma hominis, and Ureaplasma urealyticum. Of 140 fluids tested, none harbored chlamydiae, and only one harbored mycoplasma, M. hominis. A number of amniotic fluids were subsequently tested for their ability to inhibit the growth of these microorganisms. Amniotic fluids and chlamydial suspensions in a 2:1 ratio were incubated 30 to 90 minutes before their inoculation in McCoy cells. Procedures were followed for chlamydial isolation. Genital mycoplasmas were incubated with amniotic fluid samples for 24 or 48 hours at 35 degrees C. Growth in amniotic fluid specimens was compared with growth in pseudoamniotic fluid and broth controls. Fourteen amniotic fluid specimens collected from gestations of 16 to 40 weeks, were found to be inhibitory to the formation of inclusions of C. trachomatis in McCoy cells. Ten amniotic fluid specimens (16 to 39 weeks, gestation) demonstrated various degrees of inhibition against M. hominis, and three fluids were inhibitory to the growth of Ureaplasma. The inhibitor was heat and protease resistant and activity was proportional to concentration. The molecular weight of the inhibitor was probably greater than 10,000 daltons, and pH, although perhaps a contributing factor, was not the cause of the inhibition.

Effect of bacterial growth on the bursting pressure of fetal membranes in vitro

By mounting a layer of chorioamniotic membrane on a specially designed reaction vessel, we studied the effect of Escherichia coli and/or group B streptococcus growing on the decidual surface of the membranes in tissue culture or bacteriologic medium. The organisms grew equally well in either medium. When growing in tissue culture medium, either organism significantly weakened the membranes as compared with controls (membranes incubated in the absence of either organism). Membranes derived from pregnancies delivered vaginally or abdominally responded similarly. When organisms were grown in bacteriologic medium, bursting pressures did not decrease. Addition of bacteriologic medium (20-60%) to tissue culture medium did not affect bacterial growth, but inhibited significantly the lowering of bursting pressures. Bacteriologic medium also inhibited the peroxidase-H2O2-halide system in vitro. Heat-killed bacteria and/or supernatants of culture medium previously inoculated with bacteria were not effective in weakening membranes. The results suggest that live bacteria in conjunction with active membrane metabolism lead to a weakening and eventual rupture of the membranes.

Serial amniocenteses in the treatment of twin to twin transfusion complicated with acute polyhydramnios

Twin to twin transfusion, complicated by acute polyhydramnios in a monozygous twin pregnancy, is a difficult clinical problem. A precipitous course usually results in termination of the pregnancy within a few days and often is associated with a high perinatal mortality rate. Two cases are presented that were treated with repeated amniocenteses for the relief of extreme abdominal discomfort and to prevent imminent premature labor. The amount of amniotic fluid removed each time varied from 300 cc to 1200 cc, which was enough to relieve symptoms but not enough to induce uncontrolled uterine activity. A total of 3500 cc and 4750 cc of amniotic fluid were removed from the first and the second patient, respectively. The procedure was found to be safe and resulted in prolonging the pregnancies by 14 and 11 days, respectively. This management, with the addition of tocolysis and close fetal surveillance can offer some hope in an otherwise hopeless situation.