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Three Part Question

In [pregnant women with a suspected PE] presenting to the ED is what is the [clinical utility of ventilation/perfusion scans and/or helical CT scans] at [diagnosing a PE].

Clinical Scenario

A pregnant woman presents to the ED with symptoms describing a PE. A D-Dimer test you order is unequivocal so you wish to order further investigations. At that time helical CT and V/Q scanning are available, you wonder how reliable they are in pregnancy.

Search Strategy

All EBM Reviews - Cochrane DSR, ACP Journal Club, DARE, CCTR, CMR, HTA, and NHSEED 2nd Quarter 2008. EMBASE 1996 to 2008 week 25. Medline 1950-Week 2 June 2008 using the OVID interface. CINAHL 1982 to June Week 2 2008.
([{pregnanc$.mp. OR exp Pregnancy OR exp Pregnancy Complications or pregnant.mp. OR exp Pregnant Women}] AND [exp Pulmonary Embolism OR pulmonary embolu$.mp. OR pulmonary embolus.mp. OR exp Venous Thrombosis/ pleuri$.mp. OR pulmonary embol$.mp.]) AND {ventilation perfusion scan$.mp. OR pulmonary scinitigraphy$.mp. OR lung scintiscanning$.mp. OR helical CT$.mp. or exp Tomography, Spiral Computed }
LIMIT to human AND english.

Search Outcome

29 papers were found of which 28 were irrelevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
. Nijkeuter M et al 2006 The Netherlands	Literature review of four papers. Inclusion criteria for PE were helical CT, V/P scanning and compression ultrasonoghraphy (CUS).	Systematic review.	Safety of ruling put PE by using V/Q scans/helical CT in pregnancy.	High quality evidence lacking.	Search strategy could have been wider to include a greater part of the grey literature.Search Strategy not apparent.
			High probability V/Q scan	PE is confirmed
			All other V/Q scans which are abnormal.	PE diagnosis needs to be confirmed/excluded by use of helical CT or shielded CTPA
			Normal V/Q scan	PE is ruled out.

Comment(s)

According to Nijkeuter M et al helical CT is favourable over V/Q scanning as it emits a lower radiation dose to the foetus, is able to make alternative diagnoses’ and good specificity. The review also looks at the usefulness of CTPA in the exclusion of PE, but the search produced no information for this variable.

Clinical Bottom Line

With the current evidence available it can be deduced that V/Q scans and helical CT should not be interpreted differently in pregnancy.

Level of Evidence

Level 1 - Recent well-done systematic review was considered or a study of high quality is available.

References

1. Nijkeuter M, Ginsberg JS, Huisman MV. Diagnosis of deep vein thrombosis and pulmonary embolism in pregnancy: a systematic review J Thromb Haemost 2006 Mar;4(3):496-500.