Pregnancy: Likelihood Ratios

Introduction: None written.

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

Good Positive and Negative Likelihood Ratios

Finding	+LR	-LR	Comments, Study
Serum beta-hCG	inf	0	as compared to urine beta hCG, for all comers to an ED for whom pregnancy tests were ordered. In this study, urine beta hCG had sens = 100%, spec = 99.2% Study: Am J Emerg Med. 1993 Jul;11(4):434-6. PMID: 8216535
Uterine Artery Pulsation	11	0.3	only 1 study Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Patient Thinks She is Pregnant	2.1	0.4	Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Chadwick Sign	25.5	0.5	Only 1 study from Dr Chadwick. Sign is "characteristic" deep violet-blue color of anterior vaginal wall. Rarely seen before 7 weeks. Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281

Good Negative Likelihood Ratio

1.5

0.3

Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281

Good Positive Likelihood Ratio

Finding	+LR	-LR	Comments, Study
Vaginal Exam Signs	3.2	0.9	not explicitly defined Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Palpable Fundus	2.8	0.9	Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Breast Signs on Exam	2.7	0.6	not specifically defined Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Morning Sickness	2.7	0.7	Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Any Pregnancy Symptoms	2.4	0.6	morning sickness, breast tenderness / fullness, urinary frequency, or fatigue Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281

Poorly Diagnostic Findings

Finding	+LR	-LR	Comments, Study
Delayed Menses	1.1	0.8	Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Urine beta-hCG Duplicate	Sensitivity = 97%		7 days after missed period. Most urine b-hCG tests are sensitive to 20 mIU/ml. If sensitivity is at 0.5 mIU/ml then should be sensitive by 7 days after fertilization. Study: JAMA 2001 Oct 10;286(14):1759-61. PMID 11594902
Urine beta-hCG Duplicate	Sensitivity = 90%		on 1st day of missed period. Most urine b-hCG tests are sensitive to 20 mIU/ml. If sensitivity is at 0.5 mIU/ml then should be sensitive by 7 days after fertilization. Study: JAMA 2001 Oct 10;286(14):1759-61. PMID 11594902
Home Pregnancy Test	Sensitivity = 75%		Sens = 75% when used by actual patients but up to 91% when used by volunteers. Specificity not assessed but should be very high (~99%). Study: Arch Fam Med 1998 Sep-Oct;7(5):465-9. PMID 9755740

Findings With Unspecified Accuracy

Finding	+LR	-LR	Comments, Study
Goodell's Sign	No accuracy specified.		softening of the cervix, may be detected by 8 weeks of age Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Hegar's Sign	No accuracy specified.		Softening of the lower portion of the corpus of the uterus. May be seen by 6 weeks. Study: JAMA. 1997 Aug 20;278(7):586-91. PMID: 9268281
Trans-Vaginal Ultrasound	No accuracy specified.		Gestational sac by 4.5-5 weeks, double decidual sign by 5.5-6 weeks, yolk sac by 5-6 weeks, cardiac activity by 5.5-6 weeks. Trans-abdominal ultrasound would be less sensitive for these findings. Study: UpToDate http://www.utdol.com/online/content/topic.do?topicKey=antenatl/22517