There is no universal definition for hyperemesis gravidarum. It is usually diagnosed based on a combination of signs and symptoms that are not due to other causes and begin early in pregnancy, including persistent and severe nausea and vomiting, dehydration, weight loss (≥5% of pre-pregnancy weight), inability to eat and drink normally, strong limitation of daily activities, and the presence of ketones in the urine.[1][2]
In order to rule out other causes and determine the severity of the condition (which informs treatment), a clinician may perform an assessment, evaluate certain signs (like weight and blood pressure), order laboratory tests (to check hydration status, electrolyte balance, liver chemistries, nutritional status, thyroid function, etc.), and complete an obstetric ultrasound to check the health of the fetus.[3]