Several controversies exist in Hypnale bite management in Kerala. Even though leading bodies like WHO recommend against using antivenom for hypnale bites, many physicians still administer antivenom for snakebites even when the culprit snake is identified. Anecdotal experience suggests that the reasons for doing so range from lack of confidence in the identification of the snake, confusion as to whether or not to approach it syndromically and symptomatically rather than relying on the species identification, doubts as to whether there exists para-specific neutralization capability for the available polyvalent antivenom and fear of medicolegal culpability in denying antivenom in a case of 'snake envenomation'. To date, these domains and rationale have not been studied. It is also to be kept in mind that the evidence behind the WHO recommendation against the use of antivenom in Hypnale is based on expert opinion and case reports. The investigators intend to compare clinical manifestation and outcome amongst Hypnale hypnale bite patients who received the polyvalent antivenom to those who did not.

The investigators also intend to describe the clinical and laboratorical profile of patients with Hypnale hypnale envenomation .

Hump-nosed pit viper bites are the second most common snakebite presented to our institute as evidenced by the data in our snakebite registers. Acute kidney injury is reported in nearly 10% of the cases in our institute.

Since 2016, the participating institute maintains a snakebite register that records the patient's name, hospital number, date and time of the bite, hospital admission, and snake identification data after expert confirmation, if done. The investigators intend to review the cases with confirmed Hypnale envenomation and describe the clinical and laboratory profile of patients and their course of hospitalization.

Hump-nosed pit viper envenomation, the venom components, and the pharmacodynamics of the venom are unique to the region that it has missed the attention of many experts in the field. The current available polyvalent antivenom does not utilize the venom of Hypnale. Yet, antivenom is used by physicians for snakebites even when the culprit snake is identified, citing many reasons. The reasons range from snake misidentification to doubts as to whether para-specific neutralization capability exists for the available polyvalent antivenom. Often fear of medicolegal culpability in denying antivenom in a case of 'snake envenomation', and confusion as to whether or not to approach it syndromically and symptomatically rather than relying on the species identification also comes into play.

- Inclusion Criteria:

Case records of all snakebite in which the specimen brought is identified as Hump-nosed pit viper (Hypnale hypnale)

Exclusion Criteria:

• Incomplete case records from which no meaningful data can be abstracted.

Patients with Hypnale hypnale bite that were treated at a tertiary care centre in central Kerala, India during the period from April 2017 to December 2021.