Question 5: Groin lump post angioplasty

Question  5
Groin lump after angioplasty. Approach and US findings

Approach

The lump should be evaluated clinically for pulsatility and for the presence of bruits or palpable thrill. The differential diagnosis includes

  • large haematoma,
  • a pseudo aneurysm
  • AV fistula• Use a 5 -7.5 MHz linear array probe. May need a 3.5 MHz curvilinear if patient is obese
    • Start at the inguinal ligament above the puncture site and then at and below the puncture site.
    • Use colour Doppler to evaluate the patency of the femoral artery (FA) and the femoral vein (FV)
    • Search the extravascular soft tissues for evidence of large hematomas, pseudo aneurysm or AV fistula
    • Adjust colour Doppler gain threshold and flow detection parameters so that colour fills the artery and vein, but does not “bleed over” into the adjacent soft tissues.
    • Decrease the gain or increase the pulse repetition frequency (PRF) to visualize the artery and vein if a significant colour Doppler bruit secondary to an AVF is present.
    • Adjust gain and threshold to eliminate colour noise artificially written into soft tissues, such as hematomas, which may be confused with PSAs

US findings :

Haematoma:

  • area of mixed echogenicity, hypo to anechoic
  • absence of blood flow with colour Doppler
  • may get an inflammatory hypervascularity surrounding the haematoma
  • may see an actively bleeding jet
  • may be difficult to see the femoral vessels with a linear probe if the haematoma is large because it has displaced them posteriorly.
  • may be so extensive that there isn’t a discreet area of haematoma

Visible pseudo aneurysm (PSA) :

  • Vascular mass connected to the artery by a neck or tract
  • During systole there is antegrade flow into the pseudo aneurysm through the neck
  • During diastole, due to the increased pressure in the pseudoaneurysm, there is a retrograde flow out of the pseudoaneurysm  through the neck and back into the artery
  • This results in a characteristic “to-and-fro” pulsed Doppler waveform in the pseudoaneurysm neck and produces a characteristic “yin-yang” swirling color flow pattern within the body of the PSA
  • If the PSA is multilobed you get “a string of pearls’ appearance.

 

AV fistula:

  • Spectral Doppler analysis of the effected artery above the AVF will demonstrate a mono-phasic continuous waveform with elevated systolic and diastolic velocities.
  • Flow in the injured artery distal to the AVF will generally have normal pulsatility.
  • Spectral Doppler analysis of the affected vein central to the AVF and upstream will demonstrate “arterialized flow” with pulsations during systole and a lack of respiratory phasicity

 

References:

  • Radiology Key : Thoracic key  Cardiac catheterisation and intervention
  • Radiology Key : Thoracic key  Pulsatile Groin Mass in the Postcatheterization Patient

 

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