Sensitivity and specificity of amniotic fluid tests to detect infection (ie, positive bacterial culture)

Amniotic fluid test	Sensitivity (%)	Specificity (%)
Gram stain (bacteria or ≥6 leukocytes/hpf)^[1]	65	99
Glucose concentration ≤14 mg/dL^[1]	85	87
WBC concentration ≥10 cells/mm³*^[2]	88	69
WBC concentration ≥30 cells/mm³*^[2]	83	86
WBC concentration ≥50 cells/mm³*^[2]	77	87
WBC concentration ≥100 cells/mm³*^[2]	71	91
Leukocyte esterase activity (positive dipstick)^[3,4]	85 to 91	95 to 100

HPF: high power field; WBC: white blood cell.

* Fluid not bloody. Results are different when fluid is bloody.

References:

Lisonkova S, Sabr Y, Joseph KS. Diagnosis of subclinical amniotic fluid infection prior to rescue cerclage using gram stain and glucose tests: an individual patient meta-analysis. J Obstet Gynaecol Can 2014; 36:116.
Abdel-Razeq SS, Buhimschi IA, Bahtiyar MO, et al. Interpretation of amniotic fluid white blood cell count in "bloody tap" amniocenteses in women with symptoms of preterm labor. Obstet Gynecol 2010; 116:344.
Riggs JW, Blanco JD. Pathophysiology, diagnosis, and management of intraamniotic infection. Semin Perinatol 1998; 22:251.
Hoskins IA, Marks F, Ordorica SA, Young BK. Leukocyte esterase activity in amniotic fluid: normal values during pregnancy. Am J Perinatol 1990; 7:130.

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