Premature Rupture of Membranes: Likelihood Ratios

Introduction: None written.

The likelihood ratios of findings for Premature Rupture of Membranes are listed below. See the left navigation bar to change the display.

Good Positive and Negative Likelihood Ratios

Finding	+LR	-LR	Comments, Study
Ferning of Vaginal Fluid	inf	0	'ferning' refers to formation of crystals as the fluid dries (in a palm-leaf pattern). Note that cervical mucus itself will display ferning but the pattern is much thicker than that from amniotic fluid. Study: Am J Perinatol. 1990 Jul;7(3):276-8 PMID: 1695510
Fat Droplets in Fluid	35.5	0	seen by sudan black staining. Not present before term! Study: Clin Obstet Gynecol. 1991 Dec;34(4):715-22 PMID: 1778013
AFP in Vaginal Fluid	18.2	0.1	Study: Am J Perinatol. 1990 Jul;7(3):276-8 PMID: 1695510
Nitrazine pH Indicator of Fluid	3.4	0.1	alkaline pH causes a change to blue, implying that it is of amniotic origin Other studies have found specificity up to 96%. Study: Am J Perinatol. 1990 Jul;7(3):276-8 PMID: 1695510 Clin Obstet Gynecol. 1991 Dec;34(4):715-22 PMID: 1778013

Findings With Unspecified Accuracy

No accuracy specified.

"history has an accuracy of 90%" (unable to get original study since it's so old)

Patients may describe either a gush of fluid or a slow trickle

Study: Clin Obstet Gynecol. 1991 Dec;34(4):715-22 PMID: 1778013