Unilateral Lower Limb Oedema in Pregnancy

Unilateral lower limb oedema in pregnancy is a non-physiological phenomenon. It is attributed to lymphatic or venous obstruction in the lower limb, apart from local inflammatory or traumatic causes. Lymphoedema may occur following radical surgery or due to malignant infiltration or may be attributed to an infective process - namely, tuberculosis, fungal infection or filariasis of the lower limb.1 Venous causes of unilateral oedema of the lower limb are superficial vein thrombophlebitis or thrombosis, deep vein thrombosis or chronic venous insufficiency.

INTRODUCTION

Oedema is defined as clinically apparent increase in interstitial fluid volume.[2] One-third of the total body water is accommodated in the extracellular space; of this 25% is plasma volume while 75% is in the form of interstitial fluid. Physiological lower limb oedema of pregnancy is a bilateral phenomenon and is restricted to grade 1 oedema (upto ankles). It occurs due to raised venous pressure in the lower limbs secondary to pressure of the gravid uterus on the inferior vena cava. Generalised oedema is attributed to cardiac, hepatic or renal pathology, malnutrition, protein-losing enteropathy, anaemia, hypoproteinaemia and hypothyroidism.[3] Unilateral lower limb oedema and oedema which is grade 2 (upto knees) and above is pathological in its aetiology.

The various factors to be considered in the differential diagnosis of oedema are
i.Whether the oedema is localised or generalised.
ii.Whether the oedema is unilateral or bilateral,
iii.Local factors - colour, temperature, thickness and sensitivity of the skin,
iv.Investigations.[2]

CASE REPORT

Mrs. K, a 35 year old lady, registered in the antenatal OPD in the first trimester. She was gravida 2, para 1 with a previous full-term emergency caesarean section done for intrauterine growth retardation with oligohydramnios with foetal distress. The female child is now 3 years old. She had an uneventful antenatal period and came in early labour at 39 weeks gestation.

Per abdominal examination showed a full-term, single, engaged, cephalic presentation with minimal uterine activity and no scar tenderness. Per vaginal examination - cervix was 1.5 cm dilated, 50% effaced, vertex presenting part, membranes were intact, station - 2 and pelvis adequate. Admission test was reassuring. She had unilateral, right, lower limb oedema extending upto the knee and pitting in nature. The patient had noticed this swelling since 3 days. There was no history of fever, trauma, local foot infection, pain in the limb or difficulty in walking. There was no history of previous such episodes.

Lower limb examination - all arterial pulsations were well-felt, there was no evidence of cellulitis or folliculitis, inguinal lymph nodes were not palpable and no thrombosed veins were detected. The skin over the right lower limb oedema was stretched and shiny but showed no signs of inflammation. Superficial limb veins were prominent and appeared mildly distended. Passive movements of the limb were not painful and there was no calf tenderness. The clinical diagnosis was mild deep vein thrombosis of the right lower limb.

She was started on conservative management in the form of rest, limb elevation, elastocrepe bandage and tablet lasix 20 mg/day for 3 days with potassium supplements. Venous Doppler of the limb was done which showed no evidence of deep vein thrombosis of the common femoral, superficial femoral and popliteal veins. Venous Doppler of long and short saphenous veins was also normal. The sapheno-femoral and sapheno-popliteal junction did not show any evidence of incompetence. All the above mentioned superficial and deep veins had a normal lumen, the resting blood flow in these veins was normal, compressibility of veins was present and there was no reflux with Valsalva’s manoeuvre.

The patient went into spontaneous active labour 3 days after admission. Emergency Caesarean Section with tubal ligation was performed for variable decelerations in the intrapartum monitoring. A male baby, 2.55 kg with a 9/10 Apgar was delivered. Conservative management of the lower limb oedema was continued in the post-operative period in the form of limb elevation and elastocrepe bandage. Mother and baby were discharged on the 5th post-operative day in good condition. The lower limb oedema had totally subsided.

Fig 1:Unilateral lower limb oedema before treatment

Fig 2:After treatment.

DISCUSSION

Venous thrombosis or thrombophlebitis is the presence of a thrombus within superficial or deep veins of the lower limb and the accompanying inflammatory response of the vessel wall.[4] In 1856, Virchow described the factors that predispose to venous thrombosis, namely, stasis, vascular damage and hypercoagulability. Hence, pregnancy is a high risk state for venous thrombosis particularly in the third trimester and the first post-partum month.

Deep vein thrombosis (DVT) of the lower limb presents as a painful, unilateral limb swelling with tenderness, warmth, increased tissue turgor and distended superficial veins. Investigations helpful to arrive at a diagnosis are-

a) Doppler Sonography : This measures the velocity of blood flow in the veins. A thrombus is diagnosed by direct visualisation or by inference when the vein does not collapse on compressive manoeuvres. The positive predic tive value is 95% for proximal DVT while for distal DVT (calf veins), the sensitivity is only 50-75% with a 95% specificity due to difficulty in visualisation of calf veins.[4]

b) Impedance Plethysmography measures changes in venous capacitance during physiologic manoeuvres. Venous obstruction blunts the normal changes in venous capacitance with inflation and deflation of the thigh cuff. Positive predictive value for proximal DVT is 90% with poor sensitivity for diagnosis of calf DVT.

c) MRI - The accuracy of MRI for diagnosis of proximal DVT is the same as Venous Doppler.

d) Venography is an invasive tool which detects the presence of a filling defect in the vein or absence of filling of deep veins in DVT.

DVT is to be treated on an urgent basis due to its dreaded consequences of pulmonary embolism and also chronic venous insufficiency. The incidence of pulmonary embolism in untreated proximal DVT is 50% while that for untreated calf vein thrombosis is 5-20%. The patient is treated with bed rest and limb elevation till the oedema and limb tenderness subsides. Heparin infusion is started followed by warfarin anticoagulation. Calf DVT is treated for 6 weeks while proximal DVT requires 3 to 6 months of anticoagulant therapy.[4]

CONCLUSION

Pregnancy with its associated stasis of blood in the lower limbs and state of hypercoagulability is a high risk situation for deep vein thrombosis. Proximal as well as calf vein DVT is to be treated on an urgent basis to prevent pulmonary embolism and chronic venous insufficiency.

Unilateral lower limb oedema in pregnancy is pathological and all aetiologies likely to cause lymphatic or venous obstruction of the lower limb must be investigated and treated.

REFERENCES

1. Bailey and Love’s Short Practice of surgery. Revised by Mann CV, Russell RCG, Williams NS. 22nd edition, Chapman and Hall Medical UK. 1995; 187.

2.Braunwald Eugene - ‘Edema’, Chapter 37 in Harrison’s Principles of Internal Medicine, Editors - Fauci, Braunwald, Isselbacher, Wilson, Martin, Kasper, Hauser, Longo. 14th edition, McGraw-Hill. 1998; 1 : 210.

3.API - Textbook of Medicine, Editor-in-Chief Sainani GS. 6th edition. API, Mumbai. 1999; 304-8.

4..Creager MA, Dzan VJ. Vascular diseases of the extremities, Chapter 248 in Harrison’s Principles of Internal Medicine. Editors - Fauci, Braunwald, Isselbacher, Wilson, Martin, Kasper, Hauser, Longo. 14th edition. McGraw-Hill. 1998; 1.