Investigations

Urinalysis

• Ketonuria is not an indicator of dehydration severity, may be misleading, and should no longer be used
• Urinalysis can still be utilised to both confirm pregnancy and assess for the presence of nitrates which may indicate infection.

Bloods

• FBC
  • To assess for potential infection, anaemia and raised haematocrit (suggesting haemoconcentration due to dehydration)
• U&E
  • To identify the presence of AKI, the need for electrolyte replacement and guide IV fluid replacement
• Venous Blood Gas/Bedside glucose
  • Identify undiagnosed diabetes
  • Assess for possible DKA in patients with T1DM
• Can also consider TFT, LFT, Calcium, Phosphate, Amylase
  • Especially if suspicious for alternative causes of nausea and vomiting.

Imaging

Imaging is not required for all patients, but a pelvic ultrasound may be indicated to assess for viable pregnancy, multiple pregnancy and trophoblastic disease (molar pregnancy).

CT imaging may be required in a small number of patients to assess for alternative surgical causes of nausea and vomiting. This would usually be in the case of additional symptoms suggestive of a surgical pathology such as abdominal pain and fever. Consideration of the patients gestation and the pre-test probability of an alternative cause should be considered, as well as a discussion with both the patient and the relevant on-call teams, including O&G, General Surgery and Urology. Abdominal ultrasound or KUB ultrasound may be considered alternatively.

Learning Bite

Measurement of ketones in the urine is no longer recommended by RCOG Guidance, as it has been shown to be a very unreliable indicator of dehydration severity.