A 94-year-old woman remains in Samoa after being left behind for medical reasons when a cruise ship docked in Apia on Wednesday afternoon.

The MS Albatross ship, operated by German company Phoenix Reisen docked at Matautu wharf with 476 passengers and a crew of 325 on Wednesday.

But only 475 passengers were able to embark when the ship set sail, Muaausa Fiona Talouli of Samoa Global Shipping, the agent of company's agent in Samoa confirmed.

Muaausa said the elderly woman needed medical attention as soon as they arrived in Apia due to a pre-existing condition that was exacerbated by lengthy travel. 

The Consul of Germany in Samoa assisted the woman to communicate with medical staff; she spoke little English.

The Albatros has been sailing since December 23 when it departed from Monte Carlo, Monaco. It is now on its way to Nukualofa, Tonga.

"For the whole of [Tuesday] we were waiting for the recommendation from the hospital to see if she [could] continue the voyage, but they recommended that she shouldn't," Muaausa said.

"This is because her body is having some trouble with the long traveling she has been through and that is why they had to get her see a doctor."

The 94-year-old could not be named for privacy reasons, the company said.

But the company confirmed that the passenger was travelling alone; she is aiming to rejoin friends on the cruise in Auckland next week.

"Her luggage is still on the cruise ship while she is still admitted at the hospital," said Muaausa.

"She will be able to join the cruise again once she fully recovers and board a plane arranged by the cruise company.

"She wanted to leave with the cruise ship yesterday but the cruise also relies in the recommendation by the medical officers."

Muaausa commended the Ministry of Health's response and the team of five that met before the ship's docking to conduct a health screening for border control purposes. 

All other passengers met the requirements to disembark and continue the journey, said Muaausa.

"We went on board with our border control health screening and declarations, but they were also coming to make sure we were screened and had declaration forms with us too," she said.