It is believed that 36-year-old Annmarie collapsed at home as the shot-stopper and the rest of his family were preparing to celebrate Christmas.
The Dutchman had previously been given permission to his home country during the festive period and receive treatment for a knee injury from a Netherlands team doctor.
The ageing 'keeper is not set to return until more is known regarding the condition of his spouse, while the player's agent is said to have described the affair as a "private business".
Van der Sar has not made an appearance for United since the 3-0 win over Everton on November 21, owing to a knee injury.
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