Hyperemesis Gravidarum on the NCLEX
Hyperemesis vs morning sickness, the electrolyte pattern, and nursing care priorities.
The exam tests the line between normal morning sickness and hyperemesis, and the electrolyte pattern vomiting produces.
Morning sickness vs hyperemesis
Morning sickness: nausea with or without vomiting, common in the first trimester, typically improving by 12-16 weeks, no weight loss, no dehydration. Hyperemesis gravidarum: persistent vomiting with weight loss (commonly cited as more than 5% of pre-pregnancy weight), dehydration, ketonuria, and electrolyte disturbance. She cannot keep food or fluid down. This is a diagnosis of severity, not timing.
The lab pattern
Prolonged vomiting loses HCl, fluid, and potassium: Hypokalemia, hyponatremia, hypochloremic metabolic alkalosis, elevated urine specific gravity, and ketonuria from starvation metabolism. Hematocrit may look falsely high from hemoconcentration. Monitor weight daily and strict I&O.
Nursing care
IV rehydration first, with electrolyte replacement per labs. Thiamine before or with dextrose-containing fluids in prolonged vomiting: giving glucose to a thiamine-depleted patient risks Wernicke encephalopathy. NPO initially, then advance slowly: clear liquids → bland small frequent meals; separate solids from liquids; avoid triggers (odors, fatty or spicy food). Antiemetics per order: pyridoxine (B6) with doxylamine is a common first-line combination; others per provider. Weigh daily, monitor ketones and potassium, and assess the emotional load; prolonged vomiting is exhausting and isolating.
When to escalate
Signs of worsening dehydration (tachycardia, hypotension, poor turgor, scant concentrated urine), potassium falling despite replacement, inability to tolerate advancement, weight still dropping, or any neuro change. Persistent severe cases may need enteral nutrition per the provider.
Frequently asked
Why alkalosis instead of acidosis?
Vomiting ejects gastric acid (HCl). Losing acid and chloride pushes pH up: hypochloremic metabolic alkalosis. Prolonged starvation can add ketosis on top, but the classic early pattern is alkalosis.
Why thiamine before dextrose?
Glucose metabolism consumes thiamine. In a depleted patient, a dextrose load can precipitate Wernicke encephalopathy. Replace the vitamin first.
Is the fetus in danger?
With treatment, outcomes are generally good. The risks track with severity and prolonged maternal weight loss, which is why weight and ketones are monitored so closely.
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