Interoffice Memorandum: Extension of Validity of Medical Certifications on Form I-693 [December 2, 2004] [open pdf - 96KB]
"This memorandum temporarily extends the validity of civil surgeon endorsements on Form I-693 for certain adjustment of status applicants. For adjustment of status applicants, the endorsement of a civil surgeon on Form I-693, Medical Examination of Aliens Seeking Adjustment of Status, is generally valid for one year. Some adjustment of status applications are concurrently filed with an immigrant visa petition as provided for at 8 CFR 245.2(a)(2). These applications are filed with a Form I-693 as required by 8 CFR 245.5. Some of these applications remain pending for more than the one-year validity period."
U.S. Citizenship and Immigration Services: http://www.uscis.gov/