Objective We present two cases of metabolic acidosis in pregnancy occurring over a one month period at Hillingdon Hospital.

Case Report A 22 year old primigravidae booked at 11/40, subsequent routine ultrasound scans were normal. At 32+4/40 she presented with vomiting. She persistently vomited for 6 days, an arterial blood gas (ABG) showed a metabolic acidosis (pH 7.328, BE-15.4). Despite Intravenous fluids serial ABGS were increasingly acidotic. Bloods showed: deranged LFTs, raised urate, lymphocytosis and low BM. Acute fatty liver of pregnancy was suspected and an emergency caesarean section performed. Postpartum, after discussion with a tertiary centre it was felt that the acidosis was secondary to chronic vomiting rather than a liver pathology. A 33 year old Para 2 booked at 8+6/4 but failed to engage with antenatal care, with the exception of routine ultrasounds which were normal. At 29+2/40 she presented after vomiting for two days (with a background of hyperemesis throughout pregnancy) and ketotic on urine dipstick. Admission bloods showed deranged LFTs, lymphocytosis, raised Urate and ABG shortly after admission was severely acidotic (pH 7.28, BE -19.9). Acute fatty liver of pregnancy was considered and Caesarean section was performed. Postpartum and following aggressive rehydration, her acidosis rapidly corrected.

Discussion These cases are of interest as both were atypical causes of metabolic acidosis in pregnancy i.e. possible starvation ketoacidosis secondary to chronic vomiting in pregnancy. We suggest that arterial blood gases should be considered as routine investigation in pregnant women who present with vomiting on a background of chronic vomiting during their pregnancy.