Successful Induction of Labor: Likelihood Ratios

Introduction: Ability to induce labor with pitocin leading to vaginal delivery, vs needing a cervical ripening agent or having to perform C-section.

Prevalence

Population / Calculator	Prevalence	Comments / Study / Link
Women in Labor, single gestation cephalic	77.8%	Clin Obstet Gynecol. 2006 Sep;49(3):573-84. PMID: 16885664
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The likelihood ratios of findings for Successful Induction of Labor are listed below. See the left navigation bar to change the display.

Pre-Test Probability (Prevalence): %.	Post-Test Probability (Predictive Value): %.	Switch to display mode.
Note that calculating probabilities from more than one** finding is inherently inaccurate because findings are not independent. (For example, using two positive findings that share a common pathogenesis is likely to overestimate the true probability.)

Good Positive Likelihood Ratio
Finding	Result	+LR	-LR
[ + ] Bishop Score	+ 0 -	2.1	0.7
Bishop Score >= 5 (varying cutoffs used historically): position 0-2 consistency 0-2 effacement 0-3 dilation 0-3 station 0-3 See e.g. http://www.fpnotebook.com/OB/Exam/BshpScr.htm for details. Study: Clin Obstet Gynecol. 2006 Sep;49(3):573-84. PMID: 16885664

Poorly Diagnostic Findings
Finding	Result	+LR	-LR
[ + ] Transvaginal US	+ 0 -	1.9	0.6
cervical length <=20mm Study: Clin Obstet Gynecol. 2006 Sep;49(3):573-84. PMID: 16885664
[ + ] Fetal Fibronectin	+ 0 -	1.6	0.6
Study: Clin Obstet Gynecol. 2006 Sep;49(3):573-84. PMID: 16885664