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Out-patient investigation of pulmonary embolism

Three Part Question

In a [patient with suspected pulmonary embolism] is
[outpatient investigation] [safe]?

Clinical Scenario

A 58 year old woman with a history of DVT attends A&E with pleuritic chest pain. She is haemodynamically stable with normal saturations, ECG and chest x-ray. D-dimer is positive.

You would like to rule out a pulmonary embolism. You wonder whether it would be safe to discharge the patient home overnight before the CTPA, which is booked for tomorrow morning.

Search Strategy

Medline 1946- present via PubMed interface, searched on 04/2014.
{[(pulmonary adj embol$)ti.ab OR (exp PULMONARY EMBOLISM) OR
(venous adj thromboembolism)ti.ab OR (exp VENOUS THROMBOEMBOLISM) OR (pulmonary adj infarct$) ti.ab OR )PE)ti.ab]AND [(diagnosis)ti.ab OR (exp DIAGNOSIS OR (investigation)ti.ab] AND [(outpatient)ti.ab OR (exp OUTPATIENTS) OR (exp OUTPATIENT CLINICS, HOSPITAL) OR (ambulatory adj care)ti.ab OR exp AMBULATORY CARE) OR (ambulatory)ti.ab OR (PREVENT adj ADMISSION)]}

Search limited to Humans and English Language

Search Outcome

634 papers were retrieved, of which four papers were deemed relevant to answer the clinical question after abstract review.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Bauld, DL, Kovacs MJ.
128 adult emergency patients who were diagnosed outside of regular hours (54 with suspected PE, 74 with suspected DVT) were given Dalteparin 100u/kg (if imaging scheduled within 12hours) or 200u/kg (if imaging scheduled later than 12 hours). Patients then sent home. Those excluded were patients who were hypoxic, had active bleeding or high risk of bleeding, if admitted for another reason or if stroke/surgery within the last 48 hours.Prospective observational study.Adverse events within three months9/54 (7%) patients were diagnosed with PE. 7 patients (8%) in the negative test result group had bruising at injection sites – authors concluded that patients were safe to dischargeSmall study and small number of patients.
McDonald AH, Murphy R.
Study looked at 45 adult emergency patients with clinical probability of PE with a positive D dimer. Exclusion criteria were hypoxia, haemodynamic instability, right ventricular strain on ECG, pain requiring opiates, other illness requiring admission, social circumastances requiring admission, pregnancy, renal failure or thrombocytopeniaRetrospective observational studyAdverse events for one month after ambulatory management.No adverse events. 11/45 patients (25%) were diagnosed with PE.Small number of patients. Study only looked at patients in the ambulatory arm of the study and did not compare them to the other patients.
Rowlinson, JS, Deagle, J, Roseveare, CD.
Adult patients attending the acute medical unit. 133 patients thought likely to have a PE were given 1.5 mg/kg of enoxaparin and sent home for the next available VQ or CTPA. Excluded patients were those who had saturations <97%, haemodynamic instability, ECG evidence of right heart strain, symptoms at rest or comorbid conditions.Retrospective observational study.Adverse outcomes within one week and six months.22/133 (16.5%) patients were diagnosed with PE. There were eight (6%) readmissions, but not for PE. Adverse outcomes included vaginal vault haematomia. 5 deaths, but these were not attributed to ambulatory care. Small numbers of patients.
Cameron A, Ogolvie, C, Teckchandani, S and McKay G.
Adult patients with suspected PE who were admitted to AMU as in-patients. 351 patients in total had received CTPA or VQ scans of which 31 patients met low risk criteria for ‘outpatient care’. Patients excluded were those with incomplete records, age greater than 70 years, history of cancer, heart failure, chronic lung, renal or cerebrovascular disease, those with pulse greater than 100 beats per minute, systolic blood pressure less than 100, altered mental status, or oxygen saturation levels less than 90%.Retrospective observational studyAdverse outcomes e.g. death within 30 days.No adverse outcomes. Only 1/31 (3%) who would have been eligible for discharge had a positive scan for PE.Patients were not actually treated as outpatients in this study. Small numbers of patients.


The Oxford level of evidence for these papers is classed as '2b', as these are observational studies only. All papers had low patient numbers and were single-centred studies. A larger prospective multi-centred trial would be required to more adequately review the safety profile of this practice. However, the traditional practice of in-patient evaluation is not based on robust research either.

Clinical Bottom Line

It may be safe to investigate selected patients with suspected pulmonary embolus at home. Further research is needed.


  1. Bauld, DL, Kovacs MJ. Dalteparin in Emergency Patients to prevent admission prior to investigation for venous thromboembolism. Am J Emerg. Med 1999;17(1):11-15
  2. McDonald AH, Murphy R. A pilot audit of a protocol for ambulatory investigation of predicted low-risk patients with possible pulmonary embolism J R Coll Physicians Edinb. 2011; 41: 196-201
  3. Rowlinson, JS, Deagle, J, Roseveare, CD. Ambulatory investigation and treatment of patients with suspected pulmonary embolism: a retrospective review of one year’s experience. J R Coll Physicians Edinb 2006;36:12-16.
  4. Cameron A, Ogolvie, C, Teckchandani, S and McKay, G. Outpatient imaging for pulmonary embolism may only be suitable for a minority. Scottish Medical Journal 2012; 57: 14-17.