Hyperemesis Gravidarum

Hyperemesis gravidarum is severe, persistent nausea and vomiting of pregnancy causing weight loss (classically more than 5% of pre-pregnancy weight), dehydration, electrolyte disturbance, and ketosis, distinct from the far more common physiological nausea and vomiting of early pregnancy.

Ittypically peaks around 8 to 12 weeks and resolves by 16 to 20 weeks in most, though a subset have symptoms persisting longer.

Risk factors include multiple pregnancy, molar pregnancy (see that entry), a previous history of hyperemesis, and a degree of association with transient biochemical hyperthyroidism from hCG cross-reactivity at the TSH receptor.

Severity is often graded using the PUQE score (Pregnancy-Unique Quantification of Emesis).

Features include ptyalism, significant weight loss, and signs of dehydration. Prolonged vomiting carries a risk of Mallory-Weiss tearing and, if thiamine deficiency develops, Wernicke's encephalopathy, an important and preventable complication.

Clinical, with exclusion of alternative causes: urinalysis and culture to exclude UTI, TFTs (mild biochemical hyperthyroidism is common and does not usually require antithyroid treatment), and pelvic ultrasound to confirm viability and gestation and exclude molar or multiple pregnancy.

Urine ketones, U&E (hyponatremia, hypokalemia, and a hypochloremic metabolic alkalosis from vomiting are common), and LFTs (mild transaminitis is frequent) support severity assessment.

• Dietary measures (small, frequent, bland meals), ginger, and P6 acupressure for mild disease
• First line antiemetics: cyclizine 50 mg PO/IM/IV tds, or promethazine 12.5 to 25 mg PO tds, or the combination doxylamine 10 mg with pyridoxine 10 mg, 2 tablets nocte with up to 4 tablets/day
• Second line: metoclopramide 10 mg PO/IV/IM tds (limit to a maximum of 5 days given extrapyramidal side effect risk), or prochlorperazine 5 to 10 mg PO/IM tds-qds, or ondansetron 4 to 8 mg PO/IV tds (a small possible increase in cleft palate risk with first trimester use has been reported; weigh against severity when choosing first trimester timing, though it remains very widely used)
• Refractory disease: corticosteroids, hydrocortisone 100 mg IV bd, transitioning to prednisolone 40 to 50 mg PO od once improving, then tapering over 1 to 2 weeks
• IV fluid resuscitation with 0.9% saline or Hartmann's solution (avoid dextrose containing fluids until thiamine has been given, given the risk of precipitating Wernicke's encephalopathy); replace potassium as needed
• Thiamine 100 mg IV or PO daily (or 25 to 50 mg PO od) in any woman with prolonged vomiting or before administering IV dextrose
• Thromboprophylaxis (LMWH) for hospitalized women, given the elevated VTE risk with reduced mobility and hemoconcentration
• Admission indicated for ketonuria with inability to tolerate oral fluids, weight loss exceeding 5%, or a confirmed comorbidity requiring inpatient management

Referral: admission for severe or refractory disease; dietitian input; psychological support given the significant quality of life impact.