Letter to the Editor: Thiamine deficiency and bariatric surgery

To the Editor,

re. Huang et al. Micronutrient screening, monitoring, and supplementation in pregnancy after bariatric surgery. Obstetric Medicine 2021; 0: 1–8. https://doi.org/10.1177/1753495X211013624.

I thank Drs Huang et al. for their review article regarding pregnancy following bariatric surgery. ¹ I would be grateful to know if the woman described in the case report was treated with parenteral thiamine given her significant morning sickness, development of progressive peripheral oedema in first trimester when serum albumin was 26 g/l, and subsequent anasarca, ascites and pleural effusions suggesting the possibility of wet beriberi. Thiamine deficiency has been reported in 54% of individuals following biliopancreatic diversion. ² Beriberi is predominantly a clinical diagnosis, assays for thiamine deficiency lacking sensitivity and specificity, particularly in the setting of hypoalbuminaemia. Cases of wet beriberi and Wernicke's encephalopathy have been described with normal thiamine levels. ³ Clinical practice guidelines for women with previous bariatric surgery recommend testing thiamine levels preconception, as soon as the woman is pregnant, and in each trimester if deficiency is documented previously. ⁴ Urgent parenteral thiamine therapy is recommended in any pregnant woman with a history of bariatric surgery who has repeated vomiting.

An additional question is whether laparoscopic sleeve gastrectomy (LSG) is preferable to gastric bypass surgery (GBS) in women of reproductive age. Pregnancy in women following GBS is associated with higher rates of nutrient deficiencies, maternal anaemia, fetal growth restriction, early and late dumping syndrome and intestinal obstruction due to internal herniation. The latter is perhaps the most compelling reason for choosing LSG rather than GBS. A Swedish cohort study found the risk of undergoing surgery for intestinal obstruction during the first pregnancy after bariatric surgery was increased 34-fold compared with pregnancy in morbidly obese women. Fetal and maternal loss has been reported in 17% and 2% respectively with intestinal obstruction in pregnancy. ⁵ Studies directly comparing pregnancy outcomes in women following restrictive or malabsorptive bariatric surgery would be valuable to guide bariatric surgeons regarding the most appropriate procedure in reproductive age women.