"Edwin is going back to Holland," said manager Sir Alex Ferguson. "It is a change of scenery and the Holland team doctor will have a look at the injury."
It was initially thought that the injury would only keep the 39-year-old out of action for a couple of games.
But there is no immediate prospect of a return for the veteran keeper and Ferguson is keen to explore all options.
"Edwin has never had an injury like this in his life before so we think it is a good idea for him and expect him back in a couple of days," added the United boss.
How much of a blow is the absence of Van der Sar? It has been a injury-plagued season for Van der Sar, who missed the start of the campaign after breaking two bones in his left hand against Bayern Munich in the Audi Cup on 5 August.
In the absence of Van der Sar, who set a British top-flight record by going 1,311 minutes without conceding a goal last season, Tomasz Kuszczak has been starting in goal for United.
Meanwhile, Ferguson has confirmed that Portugal winger Nani will be missing for two more weeks as he recovers from the ankle injury he sustained in the Champions League victory over Wolfsburg on 8 December.
John O'Shea is also expected to be out until January with the injury he picked up playing for the Republic of Ireland, but Wes Brown (hamstring) and Gary Neville (groin) are expected back within 10 days.
Central defender Nemanja Vidic limped out of Tuesday's victory over Wolves with a calf strain but could return against Fulham on Saturday.