BANGKOK - Thailand's King Bhumibol Adulyadej, the world's longest-reigning monarch, has undergone surgery to remove his gallbladder, the palace said in a televised statement on Monday.
The declining health of the 86-year-old king has formed the backdrop to Thailand's protracted political crisis, and Monday's palace update came shortly after Prime Minister Prayuth Chan-ocha, who seized power in a coup in May, had visited the Bangkok hospital where Bhumibol is recuperating.
"On Oct. 5 medics X-rayed His Majesty and found his gallbladder very swollen. Last night at 09:45 p.m. doctors ... inserted a camera into the stomach (area) and removed the gallbladder," the statement from the palace said.
"The operation was satisfactory and His Majesty returned to his room at 20 minutes past midnight. This morning the heartbeat has lowered, blood pressure is normal and His Majesty's fever is lower. Doctors continue to administer antibiotics and continue to administer an intravenous drip."
Gallbladder removal is a common surgical procedure, usually carried out to relieve painful gallstones, and loss of the organ does not cause complications for most patients.
The king was discharged from hospital last month after nearly five weeks of treatment for stomach inflammation. He was readmitted to hospital late on Friday for what the Royal Household Bureau said was a fever and irregular blood pressure.
Junta leader Prayuth, dressed in a suit and wearing a yellow tie - a colour closely associated with the king - led a big entourage, including deputy prime ministers and Thai army chief General Udomdej Sitabutr, to Siriraj Hospital, where the group signed a book with get-well messages for Bhumibol.
Seen as a unifying figure in Thailand, Bhumibol's health is a subject of keen public concern. He is revered by many Thais and his portrait hangs in every government building and in many shops and homes.
He left the same hospital in 2013 after spending nearly four years in a special suite of the hospital after being admitted in 2009 for a lung infection.
Since then Bhumibol has rarely been seen apart from a handful of public engagements, and spends most of his time at the Klai Kangwon Palace - which translates as "Far from Worries Palace" - in the seaside town of Hua Hin, south of Bangkok.
Bhumibol, a constitutional monarch, made several interventions in the 1970s and 1990s to call for calm during political crises. He stayed silent during the latest crisis, which began in November and culminated in a May 22 coup.
Years of political strife between the Bangkok-based establishment and former Prime Minister Thaksin Shinawatra, who was ousted by the army in 2006, centres partly around anxiety over the issue of royal succession.
Bhumibol's son and presumed heir, Crown Prince Vajiralongkorn, does not command his father's popular support, but some Thaksin supporters had been expressing their loyalty to the prince during protests this year.
News about the monarchy is heavily filtered by the palace, and under tough lese-majeste laws anything deemed an insult or a threat to the monarchy is punishable by up to 15 years in jail.
Well-wishers, many of them wearing yellow, flocked to Siriraj Hospital on Monday to sign get-well books for the king and to pray for a speedy recovery. Many held framed pictures of the king as a young man.
"I was speechless when I heard that His Majesty was readmitted to hospital so soon after being discharged," said Sawek Wichaiwattana, 70, a Bangkok resident. "I wish His Majesty a speedy recovery."