20WBCT is the essential bedside test for viper envenomation in resource-limited settings.
Take 2mL of fresh venous blood in a clean, dry glass tube (not plastic)
Leave undisturbed at room temperature for exactly 20 minutes
No clot (blood remains liquid) = viper envenomation with systemic coagulopathy
Clot forms normally = no significant haemotoxic envenomation (OR neurotoxic snake)
Repeat every 6 hours for 24 hours if initial test normal (venom may take time to act)
20WBCT is POSITIVE (no clot) = VIPER BITE with systemic envenomation → give antivenom urgently. A positive result without waiting for lab results (PT/APTT) is sufficient to trigger antivenom in resource-limited settings.
Many traditional first aid measures for snake bite are HARMFUL and must be actively discouraged.
DO
DO NOT
Immobilise the bitten limb (splint, sling)
Cut and suck the wound
Keep patient calm and still — movement increases venom spread
Apply a tourniquet or tight bandage (arterial)
Remove rings, watches, tight clothing from affected limb
Apply ice or cold packs
Transport to hospital immediately
Apply electric shock
Note time of bite
Give oral fluids or food (aspiration risk)
Describe/photograph snake if safe — identification helps
Try to catch/kill the snake (risk of second bite)
Antivenom — Definitive Treatment
Antivenom is the ONLY definitive treatment for systemic snake envenomation. It neutralises circulating venom but cannot reverse already-established necrosis or organ damage.
Indications: systemic signs (coagulopathy, neurological, cardiovascular, haematuria, haemorrhage), rapid progression of local swelling
Route: IV (preferred) — dilute in normal saline, infuse over 30–60 min with slow start
Have adrenaline 0.5mg IM drawn up and ready before starting (anaphylaxis risk ~5–50% depending on antivenom)
Give antihistamine and hydrocortisone pre-medication if available (reduces but does not eliminate anaphylaxis risk)
Repeat dose after 6h if 20WBCT remains positive or systemic signs persist
Species-specific antivenom more effective than polyvalent where identification is certain
Supportive Management
Airway: for neurotoxic envenomation — early intubation if bulbar palsy or respiratory failure developing; do NOT wait until arrest
IV access × 2: large bore cannulae; send FBC, coagulation, U&E, LFTs, CK, cross-match
Urine output: monitor hourly; target ≥0.5mL/kg/hr; IV fluids for AKI/rhabdomyolysis
DIC management: FFP for coagulopathy; platelets for thrombocytopenia (<50 with bleeding); cryoprecipitate for fibrinogen depletion
Local wound: clean, sterile dressing; do NOT debride early (demarcation unclear); monitor circumference hourly
Tetanus prophylaxis: all snake bite patients require tetanus assessment and prophylaxis if not up to date
Analgesia: paracetamol + opioid PRN; avoid NSAIDs (impaired platelet function in coagulopathy)
Monitoring Protocol
Vital signs every 15–30 min initially
Limb circumference at mark every hour (haemotoxic envenomation)
20WBCT at 0, 6, 12, 24 hours
Hourly urine output
Neurological observations every 30 min (neurotoxic)
AKI is a major cause of death after saw-scaled viper bite. Mechanisms: rhabdomyolysis, DIC with renal microthrombi, hypotension, direct venom nephrotoxicity.
Monitor urine output hourly — oliguria (<0.5mL/kg/hr) = AKI alert
Myoglobinuria: dark brown urine → aggressive IV fluid resuscitation
Urine alkalinisation (bicarbonate) may reduce myoglobin precipitation in tubules
Renal replacement therapy (haemodialysis) if severe AKI with hyperkalaemia or fluid overload
Pyrogenic reaction: fever, rigors 30–180 min after infusion — slow infusion rate; paracetamol; antipyretics
Serum sickness (7–14 days later): urticaria, arthralgia, fever — oral prednisolone for 5–7 days
Snake Bite in the GCC Context
Saw-scaled viper is the most medically significant snake in the GCC — responsible for most fatal and serious envenomations
High-risk populations: construction workers, agricultural workers, farmers, herders, military personnel in rural areas
Most bites occur at night when snakes are active (nocturnal) and barefoot movement is common
Sea snakes: risk to fishermen in the Arabian Gulf and Gulf of Oman; bites while handling nets
Wadi hiking and camping increasingly popular in Oman, UAE, Saudi Arabia — increasing tourist/expatriate exposure
Traditional Remedy Delays Presentation
Traditional and folk remedies for snake bite are widely used across the GCC and South Asian communities. These include cutting, sucking, tourniquet application, herbal poultices, and cauterisation — all of which delay appropriate treatment and worsen outcomes.
Public health education campaigns about correct first aid are essential
Language barriers in migrant worker communities contribute to delayed hospital presentation
Nurses should sensitively explore pre-hospital treatment without judgement to assess any harm caused
Antivenom Availability in GCC
Saudi Arabia: VACSERA (Egyptian) polyvalent antivenom available; national snakebite centres in major hospitals
UAE: antivenom available at major hospitals; DHA maintains emergency stocks
Oman: MOH snake bite protocol; antivenom stocked at regional hospitals; Oman Toxicology Centre provides advice
Rural and remote areas: antivenom availability may be limited — air transport to nearest tertiary centre may be needed
Nurses in emergency settings should know the location of antivenom stock and how to access the on-call toxicologist for guidance
High-Yield Exam Points
Saw-scaled viper = most common + most dangerous GCC snake (haemotoxic)
First aid: immobilise, calm, remove rings — do NOT cut/suck/tourniquet/ice
20WBCT: no clot in 20 min = viper systemic envenomation → give antivenom
Antivenom = ONLY definitive treatment; have adrenaline ready before giving
Monitor urine output hourly for rhabdomyolysis/AKI
FFP/platelets for DIC; tetanus prophylaxis for all patients
Compartment syndrome: 5Ps; pressure >30mmHg → fasciotomy; do NOT elevate limb
Traditional remedies (cutting, sucking, tourniquet) = HARMFUL — delay treatment
Common Exam Traps
20WBCT: use a GLASS tube (not plastic) — plastic activates clotting factors and gives false negative
Antivenom cannot reverse established necrosis — give EARLY before irreversible damage
Neurotoxic envenomation: minimal local wound but potentially fatal respiratory failure — do NOT be reassured by a small bite wound
Avoid NSAIDs in snake bite with coagulopathy — impairs platelet function further
GCC Clinical Practice Insights
Saw-Scaled Viper: Clinical Recognition and Significance +
Echis carinatus (saw-scaled viper) is small (40–60cm), well-camouflaged in rocky terrain, and highly aggressive when disturbed. Its venom contains phospholipase A2, metalloproteinases, and coagulotoxins causing consumption coagulopathy. It is responsible for more deaths from snake bite globally than any other species. In the GCC, it is the primary concern for nurses in emergency departments receiving bite victims.
Sea Snake Bites in GCC Fishermen +
Sea snakes (Hydrophis cyanocinctus, Hydrophis spiralis) are common in the Arabian Gulf and Gulf of Oman. They are highly venomous but rarely aggressive. Fishermen are at risk when pulling in nets containing sea snakes. Envenomation causes myotoxicity (CK elevation, myoglobinuria) and neurotoxicity (respiratory failure). Local wound is often minimal. Treatment: sea snake antivenom or tiger snake antivenom (cross-reactive) + ventilatory support.
Oman National Snake Bite Protocol +
Oman's Ministry of Health has a well-developed national snake bite protocol given its biodiversity (over 20 snake species). The National Poison Control Centre provides 24-hour telephone advice. Hospitals stock regional antivenoms. The 20WBCT is standard practice in Omani emergency departments. Nurses trained in remote and wadi rescue carry specific equipment including antivenom in advance paramedic kits.
Migrant Worker Vulnerability to Snake Bite in GCC +
Migrant construction workers (from South Asia, Southeast Asia) working in rocky terrain, agricultural land, and desert sites in Saudi Arabia, UAE, Oman, and Qatar are at high risk of snake bite. Factors increasing risk: working at night/dawn, inadequate footwear, sleeping outdoors, language barriers preventing them from understanding warning signs. Occupational health education in workers' native languages and provision of appropriate footwear are key preventive measures.
Practice MCQs
Q1. A construction worker in Oman presents with a bite wound on his foot after working at night. Over 2 hours his foot has swollen to the ankle, his gums are bleeding, and he appears confused. Which type of envenomation does this suggest?
Correct answer: C — Marked local swelling + bleeding (gums) + confusion = haemotoxic systemic envenomation consistent with saw-scaled viper bite. Perform 20WBCT immediately. If no clot forms = systemic coagulopathy confirmed → antivenom urgently. Neurotoxic envenomation would show neurological signs (ptosis, weakness) with minimal local swelling.
Q2. A 20WBCT is performed on a suspected viper bite patient. After 20 minutes, blood in the glass tube has not clotted. What does this indicate?
Correct answer: A — A positive 20WBCT (blood does NOT clot after 20 minutes in a glass tube) indicates systemic haemotoxic viper envenomation with consumption coagulopathy. This is an indication for antivenom. Note: The test MUST use a glass tube — plastic tubes activate clotting factors giving falsely normal results.
Q3. A patient was bitten by a snake 30 minutes ago. His companion applied a tourniquet, cut the wound, and sucked out blood. On arrival, which statement about these first aid measures is correct?
Correct answer: B — Cutting: increases infection risk, local necrosis, and bleeding. Sucking: ineffective (only tiny amounts of venom removed), introduces oral bacteria, and may harm the person sucking if they have oral lesions. Tourniquet: causes ischaemia, increases local tissue damage, and concentrates venom in limb causing worse necrosis when released. All three should be avoided — and the nurse should document the pre-hospital interventions.
Q4. Before administering antivenom to a snake bite patient, what is the most critical preparation the nurse must make?
Correct answer: C — Antivenom carries a significant anaphylaxis risk (5–50% depending on product). Adrenaline 0.5mg IM must be drawn up and immediately available BEFORE starting the antivenom infusion. Skin prick testing is no longer recommended (unreliable and delays treatment). Pre-medication with antihistamine and hydrocortisone reduces but does not eliminate the risk.