Nausea and vomiting during early pregnancy occurs in about 70-90% of women, although in most cases it is not severe and has diminished by the mid-second trimester. Rarely, severe vomiting continues throughout pregnancy, and it may require hospitalisation in about 3-10 per 1000 women. It is referred to as hyperemesis gravidarum when there has been 5% of pre-pregnancy weight loss, dehydration and electrolyte imbalance, and other causes of vomiting have been excluded. It is more common in first pregnancies and with younger maternal age, obesity, multiple pregnancy, previous history of hyperemesis, metabolic disorders and eating disorders. The aetiology is unknown but hormonal (particularly oestrogen and human chorionic gonadotrophin), metabolic and psychological factors have been implicated.
Anaesthetists may be asked to advise on antiemetic therapy or to assist in establishing peripheral or central venous access for fluid replacement and/or nutrition. They may also be involved in providing analgesia or anaesthesia for delivery or, rarely, for termination of pregnancy if hyperemesis is very severe.
Problems and special considerations
Clinical symptoms are non-specific, and it is important to consider other causes of nausea and vomiting (Table 88.1). There maybe evidence of malnutrition and/or dehydration, with associated biochemical and metabolic derangement including ketonuria, renal and particularly hepatic impairment and mineral/vitamin deficiency, for example Wernicke’s encephalopathy. The muscle bulk is virtually always reduced in severe cases, and there may be fetal growth restriction. Because of the importance of psychological factors, these patients may need psychological or psychiatric support, which may be difficult in the maternity suite; in early pregnancy they are often managed on general gynaecological wards.
Management options
Initially, non-pharmacological methods of management are usually proffered, such as frequent small snacks (e.g. dry crackers), ginger root tea, hypnosis and use of acupressure bands or acupuncture to stimulate an area on the ventral surface of the wrist between the long flexor tendons. Electrolyte replacement drinks and oral nutritional supplements, if tolerated, are advocated. The evidence for the more esoteric treatments is somewhat mixed, although is probably strongest for acupressure or acupuncture for its general (as opposed to obstetric) antiemetic effect. Psychological support is generally advocated.
Standard antiemetics such as prochlorperazine and cyclizine are usually tried first; promazine has traditionally been used. Second-line drugs include metoclopramide (because of the increased incidence of extrapyramidal side effects in young women), domperidone and ondansetron. It should be remembered that the effects of these drugs on the fetus are unclear and that few are licensed for use in pregnancy.
Table 88.1 Causes of vomiting in pregnancy
|
Infective |
Gastroenteritis Urinary tract infection Hepatitis |
|
Surgical |
Intra-abdominal pathology Primary gastrointestinal Severe reflux oesophagitis |
|
Neurological |
Increased intracranial pressure Migraine |
|
Metabolic |
Diabetes Hypercalcaemia Uraemia Acute fatty liver of pregnancy |
|
Drug-related |
Antibiotics Analgesics Alcohol |
|
Psychogenic |
|
There is some evidence to support the use of steroids as treatment (e.g. intravenous hydrocortisone 100 mg, twice daily, then prednisolone 45-50 mg/day, reduced to the lowest possible dose). The use of diazepam has been studied in randomised trials, and its success is thought to be a result of its sedative properties. However, sedative drugs are not recommended because of their addictive properties and because of possible adverse effects on the fetus.
In cases where dehydration is apparent, hospitalisation and intravenous rehydration (and occasionally resuscitation) is required; use of glucose-containing solutions (after administration of thiamine) may provide a small amount of calorific intake, but excessive administration may result in hyponatraemia, so crystalloids containing sodium and potassium are recommended. Vitamin and mineral supplementation is advisable, and enteral nasogastric nutrition has been used. In very severe cases, parenteral nutrition may be required; use of parenteral nutrition has even been advocated as a treatment in its own right, and there are several reports of its apparent success, occasionally on repeated occasions throughout the same pregnancy. Oesophagitis may be severe and is treated by using standard methods. Thromboprophylaxis may be indicated for hospital admission with reduced mobility.
Key points
• Nausea and vomiting occurs in about 75% of pregnancies.
• Hospitalisation is required in about 3-10 per 1000 women.
• Urea and electrolyte disturbances and hepatic impairment may occur.
• There are few randomised controlled trials of therapy but many different non- pharmacological and pharmacological therapies have been used.
Further reading
Boelig RC, Barton SJ, Saccone G, et al. Interventions for treating hyperemesis gravidarum. Cochrane Database of Syst Rev 2016; (5): CD010607.
Royal College of Obstetricians and Gynaecologists. The Management of Nausea and Vomiting of Pregnancy and Hyperemesis Gravidarum. Green-top Guideline 69. London: RCOG, 2016. www.rcog.org.uk/en/ guidelines-research-services/guidelines/gtg69 (accessed December 2018).