This document summarizes an audit of CTPA scans ordered without a D-Dimer test for patients over 50. Of 53 CTPA scans reviewed, 49 did not have a D-Dimer. For most scans, the decision not to order a D-Dimer was appropriately documented. However, for 8 scans (16%) there was no documented reason for not ordering a D-Dimer. The audit concluded that CTPA scans are generally being ordered appropriately to diagnose PE, but better documentation of the reasons for not ordering D-Dimers could help reduce unnecessary CTPA use.

1. D-DIMER AND CTPA
HAN LU
DAVID MOUNTAIN

2. OBJECTIVE
▸ What is a D-Dimer (DD)
▸ Introduction / Background
▸ Inclusion / Exclusion criteria
▸ Data Points
▸ Analysis
▸ Discussion / Conclusion

3. WHAT IS A D-DIMER (DD)
▸ D-Dimer (DD) introduced since 1990s
▸ Fibrin degradation product
▸ Small protein fragments in blood post fibrinolysis.
▸ Contains 2 D fragments of fibrin protein cross linked.
▸ Useful in diagnosing a range of thrombotic pathologies.
▸ Particularly useful when negative and used as a exclusion criteria for
thrombosis.

4. INTRODUCTION / BACKGROUND
▸Recent retrospective audit on aged DD - population pt >50yo
▸≈ 500 patients per year had CTPAs
▸≈1/3rd had DD
▸≈2/3rd DID NOT have DD
▸DD omitted ?due to exclusion criteria such as e.g. symptoms >1/52, etc?
▸Audit to assess if CTPAs are requested appropriately for PE without DD
▸Can CTPAs be cut down? (Radiation CTPA = 2-3 years of BG radiation)
▸53 cases identified with a CTPA but without DD

5. INTRODUCTION / BACKGROUND
▸Recent retrospective audit on aged DD - population pt >50yo
▸≈ 500 patients per year had CTPAs
▸≈1/3rd had DD
▸≈2/3rd DID NOT have DD
▸DD omitted ?due to exclusion criteria such as e.g. symptoms >1/52, etc?
▸Audit to assess if CTPAs are requested appropriately for PE without DD
▸Can CTPAs be cut down? (Radiation CTPA = 2-3 years of BG radiation)
▸53 cases identified with a CTPA but without DD

6. INCLUSION CRITERIA
▸Cases with CTPA
and
▸No D-Dimer beforehand
and
▸Age >50 yo
‣ None SCGH ED patients
(e.g. KEMH T/F) or IP
‣ Aged <50 yo
‣ CTPA not performed for
acute PE, or for surveillance
of a known acute PE
EXCLUSION
CRITERIA
‣ 53 notes were audited, 4 were excluded due to exclusion criteria

7. DATA POINTS
▸Demographic data
▸PC - from presentation Code/triage
▸D/C diagnosis in EDIS / Topas
▸Ix for DVT/PE (DD, US, VQ, CTPA,MRPA, PA, venogram)
▸WELLS score (Prospective OR Retrospective)

8. ▸Potential reasons for not performing DD
▸Delayed symptoms (>1/52)
▸Pregnant (3rd trimester) or <1/52
postpartum
▸Recent major trauma <1/52
▸Invasive surgery <1/52
▸Current inpatient
▸Severely unwell / unstable
▸Active cancer (<6/12 since therapy /
palliative)
▸Other DVT / VTE / major thrombosis
diagnosed prev 1/52
▸High pre-test risk of PE
▸On Warfarin, NOAC, heparin
▸Reason for not performing a DD documented
▸Definitive alternative diagnosis documented before discharge home.

9. LIMITATIONS OF AUDIT
▸Based on documentation / reports
▸Auditing CTPAs for PE diagnosis
▸WELLS is subjective
▸Assumptions:
▸If calf examination not documented - assumed nil signs of DVT
▸PE most likely diagnosis - based on clinical history / examination
findings documented / differential diagnosis listed
▸If no mention of previous DVT,PE / Cancer / Recent immobilisation /
haemoptysis - assumed these were not present

10. DEMOGRAPHICS
▸Age range 50-88 (so none
were PERC able)
▸Gender female 27, male 22
▸Time / date attendance range
08/03/16 - 26/10/16
Fe
ma
l…
Ma
les
4…

11. TRIAGE CATEGORY
▸Triage category
▸2 = 35
▸3 = 11
▸4 = 3
2
71%
3
22%
4
6%

12. PRESENTING COMPLAINT

13. PRESENTING COMPLAINT
▸ Respiratory Short of Breath 17
▸ Pain – Chest 15
▸ Respiratory Cough 4
▸ Pain – Back 2
▸ Regional Problem –Infection / Inflammation
2
▸ Temperature / Environmental Fever 2
▸ Temperature / Environmental Acopia 1
▸ Cardiovascular / Palpitations 1
▸ Drug / Alcohol Use 1
▸ Neurological – Altered Conscious State 1
▸ Neurological – Syncopal 1
▸ Provisional Diagnosis – ?DVT 1
▸ Urology/Reproductive –urinary retention-
(MS) 1

14. DISPOSITION
▸Admitted 42
▸EDU 1 - TOC Ortho (CTPA - No PE)
▸Obs 2
▸ DC 1 (CTPA - No PE)
▸ TOC Resp 1 (CTPA - No PE, progression
interstitial pneumonitis)
▸DC from ED by MAU 1 (CTPA - No PE)
▸Discharged 7

15. DIAGNOSIS EDIS / TOPAS / DC SUMMARY
9
8
4
2
2
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0 2 3 5 6 8 9 11
Chest Pain Unknown Cause
PE
Pneumonia
Neoplasia - Respiratory System
Dyspnoea
Acute Cholecystitis
Aspiration Pnuemonia
Bronchitis
Cardiogenic Pulmonary Oedema
Coagulation Defect
Diazepam / Traadol OD
Fall
Generalised Infection
Generally unwell
Haemoptysis
Limb Swelling
Neoplasia - Malignant Mesothelioma
Neoplasia Metastasis to lung
Neutropenia and Febrile
Pleurisy
Shortness of Breath
Syncope not heat
Tachycardia

16. D-DIMER USAGE
▸No = 49
▸Yes = 0
▸DD cancelled in 1 case
and proceeded to CTPA
▸(No Reason
documented, WELLS 0)
▸CTPA - No PE
▸Diagnosed as NSTEMI
(Trop 2640 - 3060)

17. ULTRASOUND
▸No 42
▸Yes 7
▸1 Positive DVT / Thrombus (Positive CTPA)
▸6 Negative DVT / Thrombus.

18. CTPA
Positive, 11
Negative, 36
Inconclusive, 2

19. COULD CTPA BE REDUCED?
▸Of 36 Negative CTPA: WELLS scores range 0-11
‣ 3/36 WELLS > 6 (High pre-test probability)
‣ 33/36 WELLS <6 (Low / intermediate pre-test probability)
▸24 had appropriate reasons for not doing a D-Dimer
▸6 No reason documented
▸3 PE not on differentials in ED

20. COULD CTPA BE REDUCED?
▸Of 36 Negative CTPA: WELLS scores range 0-11
‣ 3/36 WELLS > 6 (High pre-test probability)
‣ 33/36 WELLS <6 (Low / intermediate pre-test probability)
▸24 had appropriate reasons for not doing a D-Dimer
▸6 No reason documented
▸3 PE not on differentials in ED

21. CTPA
Positive
11
Negative
36
Inconclusive 2

22. ▸Of 11 Positive CTPA: WELLS range 1-7
▸1/11 WELLS > 6 (High pre-test probability)
▸10/11 WELLS <6 (Low / intermediate pre-test probability)
▸7 had appropriate reasons for not doing a D-Dimer
▸2 No reason documented
▸1 PE not on differentials in ED
▸Of the 2 Suboptimal - Both WELLS of 2.5 + Both had reason for
not doing D-Dimer
COULD CTPA BE REDUCED?

23. ▸Of 11 Positive CTPA: WELLS range 1-7
▸1/11 WELLS > 6 (High pre-test probability)
▸10/11 WELLS <6 (Low / intermediate pre-test probability)
▸7 had appropriate reasons for not doing a D-Dimer
▸2 No reason documented
▸1 PE not on differentials in ED
▸Of the 2 Suboptimal - Both WELLS of 2.5 + Both had reason for
not doing D-Dimer
COULD CTPA BE REDUCED?

24. WELLS SCORE
1 1 1 1
5
1 1
5
2
7
10
2
2
3
1
1 1
1
1
1
1
0
3
6
9
12
15
0 1.5 3 4.5 6 7
Movement Artefact
Suboptimal
Negative
Positive

25. WELLS CALCULATED / PROSPECTIVE VS
RETROSPECTIVE
Notes
41
PE
Pathway
8
Prospective 9
Retrospective
40

26. REASON FOR NOT DOING D-DIMER
22
2
1
3
5
7
8
4
0 6 12 18 24
Active Cancer / Cancer…
Current Thrombosis
Inpatient
On Warfarin / NOAC /…
Prolonged Symptoms…
Invasive Surgery <1/52
No Reason
PE not on differential in ED
▸ No reason - 16% ▸PE not on differential in ED - 8%

27. REASON FOR NOT DOING D-DIMER
22
2
1
3
5
7
8
4
0 6 12 18 24
Active Cancer / Cancer…
Current Thrombosis
Inpatient
On Warfarin / NOAC /…
Prolonged Symptoms…
Invasive Surgery <1/52
No Reason
PE not on differential in ED
▸ No reason - 16% ▸PE not on differential in ED - 8%

28. TEXT

29. NO REASON DOCUMENTED FOR D-DIMER
Positive:
PE 2
Negative, 6
▸WELLS score Range 0-4.5
▸Based on PE Pathway - DD could have been done

30. PE NOT ON ED DIFFERENTIAL
▸All 4 were organised by admitting team. WELLS range 1.5-4.5
▸ED differential:
▸3 No PE on CTPA - Pneumonia / Chest pain unknown / Generalised
infection - PUO
▸1 CTPA: Right mid lobar + segmental PE, no right heart strain
▸ Acute Choleycystitis (EDIS)
▸PC - Neurological altered conscious state - noted to be more lethargic, T
40.1, P 120, RR 20, O2 88% RA, BP 120, nauseated (NH Res)
▸CT Triphasic - diverticulosis, potential Cholecystitis and PE

31. REASON FOR NOT DOING D-DIMER
22
2
1
3
5
7
8
4
0 6 12 18 24
Active Cancer / Cancer…
Current Thrombosis
Inpatient
On Warfarin / NOAC /…
Prolonged Symptoms…
Invasive Surgery <1/52
No Reason
PE not on differential in ED
▸ No reason - 16% ▸PE not on differential in ED - 8%

32. REASON FOR NOT PERFORMING D-DIMER
▸Not documented 42
‣ 2 used PE Pathway but left this section blank
‣ 1 mentioned D-Dimer Cancelled
‣ Documented 7
‣ 6 used PE Pathway
‣ 1 mentioned low index of suspicion of PE, but not suitable for D-
Dimer thus exclude PE with CTPA (Active cancer/cancer
treatment) (WELLS 2.5) CTPA - Neg

33. DEFINITIVE ED DIAGNOSIS DOCUMENTED
BEFORE DISCHARGED
▸Of 7 discharged patient - diagnosis:
▸1 Atypical chest pain
▸1 Chest pain
▸1 Chest pain unknown cause
▸1 Lobar pneumonia
▸1 Pneumonia
▸2 Chest wall pain

34. DISCUSSION / CONCLUSION
▸Majority of PC are Cat 2 + SOB and/or chest pain
▸Other modality used for Ix is USS
▸No reason documented for not doing DD 8/49 (16%)
▸Neg CTPA - 6/33 (18%) - Low/Int for PE - No documented reason for not
doing DD
▸Pos CTPA - 2/10 (20%) - Low/Int for PE - No documented reason for not
doing DD
▸Majority of WELLS calculated retrospectively from notes.
▸Those that used PE pathway - Great compliance to documentation

35. ▸Most common reason for not doing DD was active cancer
▸Not an exclusion criteria, part of WELLS only
▸Still some benefit for doing DD
▸PE was not on differential in ED 4/49 (8%)

36. ▸Most common reason for not doing DD was active cancer
▸Not an exclusion criteria, part of WELLS only
▸Still some benefit for doing DD
▸PE was not on differential in ED 4/49 (8%)
▸Overall, CTPAs are being ordered appropriately, BUT…
▸Compliance with PE pathway will improve documentation
and would reduce any unnecessary CTPAs