Penetrating Venomous Marine Injuries

Penetrating injuries typically occur while handling fish or during water activities (fresh or marine), and are more painful than the trauma alone would suggest — pain severity relates to venom, not just the wound.

Venomous fish

Important Australian venomous fish: catfish, stonefish, scorpion fish. Cause puncture wounds with pain proportional to venom injected. Stonefish and bullrout tend to sting the foot (trodden on); catfish tend to sting fingers/hands (handled).

• Antivenom available for stonefish — dose is 1 vial for everyone, given IV or IM; consider if simple analgesia doesn’t control pain. Discuss with a toxicologist.

Stingray

Causes both direct trauma and venom-related tissue necrosis. Usually an ankle injury (trodden on, tail whips up behind the leg), but divers may sustain thoracic/abdominal trauma. Large penetrating injuries — especially thoracoabdominal — can be fatal; major trauma management takes priority over envenomation management, and spines should not be removed before hospital assessment.

Sea urchins

Spines break off and can remain embedded; pain is generally not severe but multiple retained spines cause persistent pain. X-ray/ultrasound helps confirm retained spines, which need removal (may require surgical referral if deep).

Sponges

Rare. Cause local pain, tingling, paraesthesia and/or itch developing over hours, usually resolving within a day. Fire sponges (Tedania spp.) can cause erythema, swelling and desquamation up to 2 weeks after contact. First aid: clean the wound, simple analgesia, antihistamines — there’s no specific treatment.

Treatment (fish/stingray/urchin injuries)

• Hot water immersion (45°C) for up to 90 minutes — check water temperature against an unaffected limb to avoid burns; provides symptomatic relief while immersed, though pain often returns once stopped.
• Thoroughly clean and irrigate the wound.
• X-ray/ultrasound to confirm all spine fragments removed.
• Lacerations are best left open for delayed primary closure.
• Consider surgical exploration/washout for deeper-tissue involvement.
• If hot water and oral analgesia are insufficient, use titrated IV opioids and consider local/regional anaesthesia to assist debridement (don’t combine local anaesthetic with hot water).

Antibiotic prophylaxis

Consider if:

• Surgical decontamination was required
• The wound is significantly contaminated
• It’s a marine animal bite

Early empirical antibiotics if the patient has risk factors for infection: liver disease, iron overload, immunocompromise, diabetes, malignancy.

Secondary infection is the most important complication, especially with larger/unclean wounds — typical organisms are Vibrio spp. (marine) and Aeromonas spp. (freshwater). Review every 1–2 days for the first week after discharge; commence antibiotics if there’s evidence of infection (after swabbing).

Ensure tetanus is up to date.

From Marine envenomations, Berling & Isbister, Australian Family Physician 44(1-2), 2015 (reprinted).