Speaking on Twitter, the 69-year-old actor posted the details of the latest procedure.
"The night started off with great apprehensions, what with the temperature of the fever going up - always a dangerous signal. But the mercury fell during the night…
"Soon afterwards though, the additional pain that has developed in the abdomen, apart from the surgical, kept doctors busy and going into a huddle. Whenever they do that I always surmise there is something more than normal in the patient."
Quoting a hospital source, PTI reports: "He was supposed to undergo second surgery as he had developed pain post the first surgery. However, there is no hassle as such... he is not critical but under observation."
With news of another surgery, fans swamped Twitter with anxious messages, in response to which Bachchan posted: "I refrain from giving greater details of my condition... In the West [the] patient has the right to not disclose - even to family!!"
He added: "I realise anxious members of EF and TwFmXt need to know... Whenever there is some important procedure, will inform!"
Amitabh Bachchan has been battling a string of stomach ailments since the famous and near-fatal intestinal injury he suffered while filming a fight scene in the 1982 movie, Coolie.
Abhishek Bachchan, Aishwarya Rai Bachchan, daughter Shweta Bachchan-Nanda, Anupam Kher and wife Kirron, Sanjay Dutt and wife Maanyata, and other industry colleagues have visited the hospital where Bachchan was admitted on February 11th.