Excessive vomiting in early pregancy -Hyperemesis Gravidarum

An ultrasound scan of the uterus should be performed to comfirm  gestational age and to diagnose multiple pregnancy and exclude hydatidiform mole, both of which are associated with an increased incidence of hyperemesis. Blood tests usually reveal the following : - Hyponatraemia – Hypokalaemia.- Low serum urea . - Metabolic hypochloraemic alkalosis. – Ketonuria. Raised haematocrit  of level and increased specific gravity of urine. Abnormal liver function tests (found in up to 50% of cases bnormal thyroid function tests (found in up 66% of cases),, The picture is that of a biochemical hyperthyroidism with a raised free thyroxine and/or a suppressed thyroid-stimulating hormone(TSH)..Patients with these abnormalities  are clinically euthyroid without thyroid antibodies, except the very rare case of thyrotoxicose presenting in early pregnancy. The abnormal thyroid function tests do not require treatment with anti-thyroid drugs and resolve as the Hyperemesis inproves  .There is an increased incidence of gestational thyrotoxicosis demonstrated in Asians compared to Europeans.

Pharmacological treatment

1)   Anti-emetics

Post-thalidomide anxiety has resulted in an understandable reluctance to pre-scribe anti-emetics for hyperemesis.Anti-emetics should be offered to women with nausea and vomiting in pregnancy in the community to improve symptoms and prevent the need for secondary care.

2)   I v Fluids: RL very slowly 6 hrs 500 ml (5% dextrose may kill her by utilizing all  the thiamine in bodyàencephalopathy).Women presenting to secondary care who do not respond to i.v. fluids and electrolytes alone should be offered anti-emetic therapy.Extensive data exist to show a lack of teratogenesis or other adverse pregnancy outcome with

 C) Antihistamines (H1-receptor antagonists, e.g., 1) promethazine, 2) cyclizine,3)  cinnarizine, 4) doxylamine, dimernhydrinate) 5) Phenothiazines (chlorpromazine, prochloperazine)

D) Dopamine antagonists (metoclopramide, domperidone)

 E) Serotonin (5HT3) inhibitors (ondansetron)

If symptoms do not improve, the anti-emetic should be prescribed and given regularly rather than on ‘as required’/p.r.n. basis.Side effects include drowsiness, particularly with the phenothiazines, and extrapyramidal effects and occulogyric crises, particularly with metoclopramide. Extrapyramidal effects usually abate after discontinuation of the drug and oculogyric crises may be treated with antimuscarinic drugs such as benzatropine 1-2 mg intramuscularly Metoclopramide is safe and effective but because of the risk of extrapyramidal side effects it should be used for second line therapy

F) Ondansetron is safe and effective but because data are more limited it should be used as second line therapy . Table 12.2 shows recommended anti emetic therapies and doses.

Therapy	Dose, route and frequency
First line
Cyclizine	50mgp.o,i.m or i.v.hourly
Prochlorperazine	5-10mgp.o,i.m,i.v or p.r. 6-8 hourly 12.5 mg i.m/i.v.8 hourly 25 mg p.r. daily
Promethazine	12.5-25mg i.m,i.m ,i.v or p.r 4-8 hourly
Doxylamine plus pyridoxine	10 mg of each up to 8 tablets per day
Second line
Metoclopramide	5-10 mg i.m. ,i.v or i.m 8 hourly (maximum 5 days duration)
Domperidone	10 mg i.m. 8 hourly 30-60 mg p.r. 8 hourly
ondansetron	4-8 mg i.m. 6-8 hourly 8 mg over 15 minutes i.v. 12 hourly
Chlorpromazine	10-25 mg i.m, i.v or i.m 4-6 horly 50-100 mg p.r 6-8hour

Histamine  D2  receptor blockers and proton pump inhibitors safe . H2 receptor blockers and the PPIs are used in cases where oesophagitis or gastritis accompanies the nausea and vomiting of HG. They are safe for use in pregnancy