What is… Swelling in Legs?

A practical guide to causes, assessment, and medico-legal relevance.

Swelling in the legs is a common clinical symptom — but one that often hides a wide range of possible causes, from the benign to the life-threatening. In the context of personal injury or clinical negligence claims, unexplained or poorly managed leg swelling can be a red flag for delayed diagnosis, substandard care, or missed opportunities for prevention.

In this article, we’ll break down what leg swelling is, the key causes, how it should be assessed, and where it becomes relevant in legal and expert witness work.

What Is Leg Swelling?

Medically referred to as peripheral oedema, swelling in the legs typically occurs when fluid accumulates in the tissues of the lower limbs. This may affect one leg (unilateral) or both legs (bilateral) and can involve the feet, ankles, calves, or entire lower limb.

Swelling may be:

• Pitting: leaves a dent when pressed

• Non-pitting: does not leave a dent; often associated with lymphatic causes

While it may be harmless in some cases (e.g. prolonged standing), persistent or painful swelling warrants further investigation.

Common Causes of Leg Swelling

1. Venous Insufficiency

One of the most common causes of chronic bilateral swelling, especially in older adults. The valves in the veins become weak, leading to fluid pooling.

2. Deep Vein Thrombosis (DVT)

Unilateral swelling (especially if sudden, painful, and red) may indicate a DVT — a medical emergency due to the risk of pulmonary embolism.

3. Heart Failure

When the heart can't pump effectively, fluid backs up in the body — often presenting first as bilateral leg swelling.

4. Kidney or Liver Disease

These can cause fluid retention and hypoalbuminemia, contributing to swelling in both legs (and often elsewhere).

5. Lymphoedema

Chronic swelling due to impaired lymphatic drainage, often non-pitting and affecting one or both legs. May follow cancer treatment or be congenital.

6. Injury or Infection

Trauma to the leg — such as soft tissue damage or cellulitis — can cause localised swelling and redness. Important in personal injury claims following accidents.

7. Medication Side Effects

Certain drugs, including calcium channel blockers, steroids, and NSAIDs, can contribute to leg oedema.

Clinical Red Flags: When Swelling Needs Urgent Action

Legal professionals and clinicians alike should be alert to the following:

• Unilateral swelling + pain → suspect DVT

• Swelling + breathlessness → consider heart failure or PE

• Sudden increase in swelling post-surgery → rule out thrombotic events

• Red, hot leg with systemic symptoms → consider infection (e.g. cellulitis, sepsis)

Failure to assess and act on these red flags in a timely manner may constitute substandard care in clinical negligence claims.

How Should Leg Swelling Be Assessed?

Good medical assessment includes:

• History taking: duration, triggers, medication, trauma, comorbidities

• Physical exam: checking for signs of pitting, asymmetry, warmth, colour changes

• Basic investigations: D-dimer, ultrasound Doppler (for DVT), ECG, BNP (heart failure), blood tests (renal/liver function, albumin)

A thorough and well-documented assessment protects both patients and professionals — and plays a crucial role in any subsequent litigation or expert witness analysis.

Swelling in Legs in Personal Injury and Clinical Negligence Claims

At Apex Experts, we regularly support solicitors and medico-legal professionals dealing with cases involving leg swelling, such as:

• Missed DVTs leading to pulmonary embolism or death

• Injury-related swelling from soft tissue trauma, crush injuries, or fractures

• Post-surgical complications where swelling was not monitored

• Delayed referral for oedema investigation resulting in avoidable deterioration

• Pressure damage from immobilisation and poor care planning

In many cases, expert witnesses are asked to comment on:

• Whether leg swelling was assessed in line with guidelines

• If warning signs were documented or acted upon

• Whether the resulting harm was avoidable with timely intervention

Why This Matters Medico-Legally

Swelling may seem like a minor symptom, but it’s often the first visible sign of something more serious. A missed opportunity to investigate swelling could result in:

• Amputation

• Stroke or PE

• Cardiac complications

• Death

For clinicians, this highlights the need for proactive assessment. For solicitors, it underscores the value of early screening reports and robust expert evidence in uncovering where things went wrong.

Final Thoughts

Swelling in the legs is more than just a discomfort, it can be the start of a cascade of complications if not assessed and managed correctly. In medico-legal settings, it’s a subtle but significant symptom that often reveals failures in vigilance, documentation, or timely escalation.

Whether you’re investigating a personal injury, fatality, or delayed diagnosis claim, understanding the clinical approach to leg swelling can help determine causation, liability, and value.