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Three Part Question

In [women presenting with vaginal bleeding] can a [single measurement of Progesterone] [rule out/diagnose an ectopic pregnancy]?

Clinical Scenario

A 31 year old women presents to accident and emergency with vaginal bleeding. You wonder if a single measurement of serum progesterone can be used to diagnose or rule out an ectopic pregnancy?

Search Strategy

Medline 1966-06/05 using the OVID interface
Embase 1980-06/05
CINAHL 1982-06/05
The Cochrane Library Issue 2, 2005
{([ectopic pregnancy.mp. or exp Pregnancy, Ectopic or tubal pregnancy.mp. or exp Pregnancy, Tubal or abdominal pregnancy.mp. or exp Pregnancy, Abdominal or extrauterine pregnancy.mp] AND [exp PROGESTERONE or progesterone.mp]) LIMIT to humans and enlgish language}
Cochrane 'ectopic pregnancy' AND 'progesterone'

Search Outcome

118 papers were found using Medline, there was 1 meta-analysis. The search was repeated but limited between 2005 and 1998 giving 35 papers, of which 1 was relevant

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Mol BW et al 1998 ENGLAND	26 studies evaluating the performance of a single serum prgesterone measurement in the diagnosis of ectopic pregnancy	Meta-analysis	Pregnancy failure from viable IUP	Almost perfect specificity with a sensitivity of 60%, or 95% sensitive with a specificity of 40%	No threshold values are given for the above specificities and sensitivities for distinction between pregnancy failure and viable IUP and ectopic pregnancy from non-ectopic pregnancy
			Ectopic pregnancy from non-ectopic	Specificity >90% with a sensitivity of 15% or 95% sensitive with a specificity of <40%
			Ruling out pregnancy failure	Threshold value of 20ng/ml: Sensitivity 95% with a specificity of 40%
Buckley RG et al 2000 UNITED STATES	716 symptomatic first-trimester emergency department patients with abdominal pain or vaginal bleeding at a tertiary care military teaching hospital had progesterone levels measured by radioimmunoassay with results unavailable to the treating physician. All patients were monitored until a criterion standard diagnosis of intrauterine pregnancy or ectopic pregnancy was confirmed	Derviation study	Ectopic pregnancy	Progesterone level <22ng/ml`: Sensitivity 100%, Specificity 24%, PPV 9% and NPV 100%

Comment(s)

The two studies both had different cutoff values. The meta-analysis reported a lower sensitivity to the other study, which reported 100%.

Clinical Bottom Line

A single measurement of serum progesterone is insufficiently sensitive and specific to allow a definite diagnosis of ectopic pregnancy. However, it can help determine the risk.

References

1. Mol BW. Lijmer JG. Ankum WM. van der Veen F. Bossuyt PM The accuracy of single serum progesterone measurement in the diagnosis of ectopic pregnancy: a meta-analysis Human Reproduction 1998;13(11):3220-7
2. Buckley RG. King KJ. Disney JD. Riffenburgh RH. Gorman JD. Klausen JH Serum progesterone testing to predict ectopic pregnancy in symptomatic first-trimester patients Annals of Emergency Medicine 2000;36(2):95-100, 2000