What colour-mari are your stools?
BMJ 2005; 331 doi: https://doi.org/10.1136/bmj.331.7521.881 (Published 13 October 2005) Cite this as: BMJ 2005;331:881
- Erle C H Lim, consultant neurologist (mdcelch{at}nus.edu.sg),
- Raymond C S Seet, register,
- Benjamin K C Ong, associate professor and head,
- Vernon M S Oh, professor and senior consultant
- Department of Medicine, National University Hospital, Singapore
- Department of Medicine, National University Hospital, Singapore
My mother, who had undergone endoscopy a few months earlier to investigate what thankfully turned out to be irritable bowel syndrome, caused me no end of worry when she informed me that she had black and tarry stools. I was contemplating sending her back to the gastroenterologist for a consultation, when she mentioned, in the course of the conversation, the marvellous new Italian restaurant that had just opened. Somehow a bulb flashed in my head, and I asked her, hesitantly, what she had eaten.
“Squid ink pasta,” she replied, and wittered on about how hard it was to clean off her new blouse after spilling some on herself.
This brought to mind how one of our colleagues had, a few days earlier, fretted about the possibility of gastrointestinal bleeding and underlying malignancy when he, too, had passed black tarry stools. We reminded him of the huge plate of squid ink pasta he had consumed at lunch, which—in the absence of abdominal pain, loss of weight, and analgesic consumption—made a more sinister diagnosis unlikely, especially when he had no recurrence thereafter.
These incidents caused some merriment, after which they were promptly forgotten, until a dinner recently, when two of us who shared a plate of squid ink risotto found that even half a plate of the stuff could turn our stools black and even a little tarry.
Melaena refers to black and tarry stools from the presence of altered blood, and is usually associated with upper gastrointestinal haemorrhage. The usual culprits of “pseudo-melaena” are iron tablets (which interestingly cause greenish rather than black stools), beets, liquorice, and Pepto-bismol. Squid ink is now believed to have antiretroviral and antitumour activity, but it has been popular in Italian and Asian cuisine for ages.
We feel this phenomenon is noteworthy, in that pseudo-melaena from squid ink consumption might prompt unnecessary investigations, though it would be ironic if it also prompted the discovery of lesions that might otherwise not have been investigated.