Maternal & Newborn · Topic 43 of 48
Hyperemesis Gravidarum
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Hyperemesis Gravidarum
Persistent, severe vomiting in pregnancy with weight loss over 5%, dehydration and ketonuria. The danger is electrolyte loss — and Wernicke encephalopathy if dextrose goes in before thiamine.
Why it happens
Vomiting loses hydrochloric acid; starvation makes ketones
Nausea and vomiting of pregnancy usually starts around 5 weeks, peaks around 9 weeks and resolves by about 16–18 weeks; hyperemesis beyond that is uncommon.
Who gets it
Anything that raises hCG raises the risk
What you'll see
Can't keep fluids down — and the weight shows it
Labs & diagnostics
Ketones positive · K⁺ and Cl⁻ low · pH alkaline
Hyperemesis is a diagnosis of exclusion; an ultrasound also checks for multiple gestation or a molar pregnancy. Mild, transient hyperthyroidism (low TSH) and raised liver enzymes can occur and usually settle as vomiting resolves.
Red flags
Confusion, ataxia and abnormal eye movements are the triad of Wernicke encephalopathy from thiamine deficiency.
Treatment
Give thiamine before any dextrose-containing fluid
IV fluids; replace potassium and magnesium as needed
First line: vitamin B6 alone or with doxylamine
Then ondansetron, metoclopramide or promethazineNPO until vomiting is controlled, then fluids
Then small, frequent, bland mealsEnteral tube feeding or parenteral nutrition
Drug cautions and other options
Nursing priorities
Morning sickness or hyperemesis?
Judge by the consequences, not the misery
| Morning sickness | Hyperemesis | |
|---|---|---|
| Fluids | Keeps fluids down | Can't keep fluids down — dehydration |
| Weight | Holds weight | Loses over 5% of prepregnancy weight |
Teach your patient
Vomiting for days in early pregnancy: thiamine before dextrose, potassium back in, weigh every day. Weight loss over 5% plus ketonuria makes it hyperemesis.
Sources · Hyperemesis Gravidarum (StatPearls) · Hyperemesis Gravidarum (Merck Manual) · Maternal-Newborn Nursing 12.2 Conditions Limited to Pregnancy (OpenStax) · Nausea and Vomiting of Pregnancy, Practice Bulletin 189 (ACOG) · Wernicke Encephalopathy (StatPearls) · Zofran Prescribing Information (FDA) · Follow your facility's protocol for IV fluid and electrolyte replacement.
Hyperemesis Gravidarum
Hyperemesis gravidarum is persistent, severe vomiting in pregnancy that causes weight loss of more than five percent of prepregnancy weight, dehydration, and ketonuria, which means ketones in the urine. It is more likely when hCG runs high, as with a multiple gestation or a molar pregnancy, and after hyperemesis in an earlier pregnancy. Because vomiting loses hydrochloric acid from the stomach, expect low potassium, low chloride, and metabolic alkalosis. Care starts with rest for the stomach: the patient stays NPO until the vomiting is controlled, then moves to fluids and small, frequent, bland meals. IV fluids replace volume and potassium. The first-line antiemetic is vitamin B6, alone or with doxylamine, with ondansetron, metoclopramide, or promethazine added when needed. One rule protects the brain: give thiamine before any fluid that contains dextrose, because glucose in a thiamine-depleted patient can trigger Wernicke encephalopathy, which shows up as confusion, an unsteady gait, and abnormal eye movements. Track daily weight, intake and output, urine ketones, and electrolytes, and offer real emotional support.
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