The turn that changed the plan.
A 42-year-old male, postoperative day 2 after major abdominal surgery, was oliguric with rising urea and creatinine. Nephrology recommended urgent haemodialysis. He had a right internal jugular central line in situ, running a noradrenaline infusion for haemodynamic support. The plan was to place a dialysis catheter. The question was where.
The right femoral vein was assessed first. In transverse view, it looked normal — patent and compressible. On rotating the probe to longitudinal view, a small floating thrombus was seen. The femoral approach was abandoned. The left internal jugular vein was assessed, found clear, and a dialysis line was placed there uneventfully.
That 90-degree rotation was the difference between a routine procedure and a potentially catastrophic embolic event.
↓ Scroll down to view the POCUS clip
The patient had a right IJV CVC actively infusing noradrenaline. This line was maintaining his perfusion pressure. Disturbing it risked haemodynamic collapse. Exchange over a wire was considered unattractive given his coagulopathy and the risk of malposition. Additionally, preserving internal jugular veins for future fistula formation is a core principle in renal replacement therapy planning. The right IJV was therefore both occupied and protected.
With the right IJV occupied and the left IJV not yet assessed, the right femoral vein was selected as the primary candidate. It offers a large-calibre vessel, is compressible if bleeding occurs, and allows straightforward ultrasound-guided cannulation. The plan was to assess the vessel with POCUS before puncture.
The ultrasound probe was placed on the right femoral region. In transverse view, the vein was patent, compressible, and appropriately located medial to the artery. On switching to longitudinal view, a small floating thrombus was visualised within the femoral vein — an incidental finding that changed management entirely.
The finding was communicated to the consultant. The femoral approach was abandoned. With the right IJV occupied by noradrenaline and the right femoral vein thrombosed, the left internal jugular vein became the viable option. It was assessed with ultrasound: patent, compressible, and without thrombus. A decision was made to proceed with ultrasound-guided HD line placement in the left IJV.
A dual-lumen haemodialysis catheter was placed in the left IJV under real-time ultrasound guidance using an in-plane longitudinal approach. The procedure was uncomplicated. The patient was connected to haemodialysis without delay, and the noradrenaline infusion continued uninterrupted through the right IJV line. A formal lower-limb venous Doppler was arranged post-procedure to characterise the femoral thrombus and guide anticoagulation.
The transverse view showed a normal, collapsible femoral vein. Had the examination stopped there, the needle would have entered a vein containing a floating thrombus. The longitudinal view revealed what the transverse view concealed: an echogenic, mobile intraluminal structure with a free-floating tail.
De-identified longitudinal-view clip showing the mobile thrombus that changed the access plan.
A free-floating (non-occlusive) thrombus in the femoral vein carries a significantly higher risk of embolisation than a wall-adherent thrombus. Manipulation of the vein — needle puncture, guidewire insertion, catheter advancement — can dislodge the thrombus, leading to pulmonary embolism. In a patient with a patent foramen ovale, paradoxical embolism to the systemic circulation (including stroke) is a catastrophic possibility. In a patient on noradrenaline for haemodynamic support, any additional cardiopulmonary insult could be fatal.
By identifying the thrombus before needle insertion, the following complications were prevented:
| Complication | Mechanism | Severity |
|---|---|---|
| Thrombus dislodgement → PE | Mechanical disruption of free-floating thrombus by needle, wire, or catheter during cannulation | Life-threatening |
| Thrombus propagation | Foreign body (catheter) placed in thrombosed segment acts as nidus for proximal and distal extension | High |
| Line dysfunction / occlusion | Catheter tip embedded in thrombus prevents adequate blood flow for HD | Moderate |
| Post-thrombotic syndrome | Additional endothelial injury and thrombus extension increase risk of chronic venous insufficiency | Moderate — Chronic |
| Paradoxical embolism | Dislodged thrombus crosses PFO → systemic embolisation (stroke, mesenteric, limb) | Catastrophic |
| Haemorrhage at puncture site | Coagulopathy + venous puncture in partially thrombosed segment | Moderate |
| Vasopressor interruption | If right IJV had been disturbed during a rushed alternative approach | Life-threatening |
The following frameworks informed the clinical reasoning:
AKI is defined by a rise in serum creatinine ≥0.3 mg/dL within 48 hours, or ≥1.5× baseline within 7 days, or urine volume <0.5 mL/kg/h for 6 hours. Stage 3 AKI mandates renal replacement therapy when accompanied by refractory fluid overload, hyperkalaemia, or uraemic complications.
KDIGO Clinical Practice Guideline for Acute Kidney Injury, 2012The "Fistula First" initiative prioritises AV fistula creation for chronic HD. For acute dialysis, temporary catheters should avoid the internal jugular veins where possible if the patient may become a candidate for permanent access.
KDOQI Vascular Access Guideline, 2019 UpdateReal-time ultrasound guidance is the standard of care for internal jugular and femoral vein cannulation. Pre-procedure ultrasound assessment of vessel patency, thrombosis, and adjacent structures is recommended.
SIR Quality Improvement Guidelines, 2010; ASA Practice Advisory, 2022Free-floating proximal DVT carries a 2–3× higher risk of PE than wall-adherent thrombus. In acute illness with coagulopathy, the threshold for avoiding mechanical manipulation of a thrombosed vein should be low.
ISTH Scientific Subcommittee on DVT, 2021Two-plane imaging (transverse + longitudinal) is the minimum standard for comprehensive vascular assessment. The transverse view confirms vessel identity and patency; the longitudinal view assesses thrombus, valves, and intraluminal pathology.
ACEP Emergency Ultrasound Guidelines, 2016; WINFOCUS ConsensusIn AKI with DVT, anticoagulation must be balanced against bleeding risk. Low-molecular-weight heparin is preferred where renal function permits; unfractionated heparin is favoured in HD-dependent patients due to reversibility.
SCCM/ISTH Guideline on VTE Prophylaxis in Critical Illness, 2021Never declare a vein "clear" based on transverse imaging alone. The transverse view confirms vessel identity and compressibility. The longitudinal view detects intraluminal thrombus, assesses valve morphology, and confirms wire and catheter course. In vascular access, these two views are not alternatives — they are complementary halves of a complete examination. Skipping the longitudinal view is not a time-saving measure; it is a diagnostic omission. And when the patient in front of you is on noradrenaline, oliguric, and running out of access options, that omission can cost everything.
This case is about the quiet diligence that prevents catastrophes before they begin. The SGE-ICU call was routine. The patient was typical of a post-operative abdomen — septic physiology, capillary leak, renal shutdown, vasopressor-dependent. The anatomy, on first glance, was unremarkable. The only thing that stood between an uncomplicated procedure and a potentially fatal pulmonary embolism was the habit of rotating the probe ninety degrees.
When a vessel looks normal in the view you expect to use, there is a powerful cognitive pull to proceed. The transverse view of the femoral vein was reassuring. The patient was unstable. The consultant was waiting. It would have been easy to rationalise skipping the longitudinal assessment. But the longitudinal view does not exist to confirm what you already believe. It exists to find what you are not looking for.
This case has been fully de-identified. No institutional or departmental identifiers are included. Patient age, specific procedure details, vasopressor doses, and timeline elements have been generalised where necessary to protect confidentiality, consistent with HIPAA principles, India's Digital Personal Data Protection (DPDP) Act 2023, and NMC ethical guidelines. This content is for educational reflection only and does not represent the views of any institution, employer, or training program, and is not a substitute for independent clinical judgment.