Here is some information I found about white uniforms for the Army.
Army White Uniform[edit]
One of the Army's Dress Uniforms, the Army White Uniform,[11] was the army's equivalent to the dress white uniform worn by officers in the U.S. Navy, but unlike the navy, which mandates the owning and wearing of the white uniform throughout the summer months (year round in tropical locations) by all ranks (E-1 to O-10), the Army white uniform was an optional uniform, and was only required to be purchased by officers and sergeants major assigned to posts in the tropics and the southern United States. The Army white service uniform was phased out in 2014.
Introduced in 1902 as a summer undress uniform, its wearing, along with the dress and undress blue, was suspended during World War I and was reintroduced in its present form, along with the modern-day dress blue uniform, in 1938.[12] In its original (1902) form the white uniform included a standing collar and white flat braid trimming the coat edges.[13] The 1938 model substituted a white coat without braid and with an open-fronted peak lapel worn with a white shirt and black tie.
With the impending hostilities of World War II, production of both the blue and white dress uniforms were suspended, but the Army white uniform itself served as a model for the Army winter service uniform, which was introduced in 1942 (replacing a belted version designed around the Sam Browne Belt) and discontinued in 1968. The shirt and trousers "class B" uniform was replaced with the Army green class "B" uniform in 1985. The post-war belt-less Army Blue Uniform, and the Army green uniform, had earlier replaced the World War II "Pinks & Greens" and pattern 1942 service coat or "Eisenhower jacket" uniforms in 1956.
Like the Army green uniform, the Army white uniform featured a main jacket with four buttons, worn with matching white trousers and service cap, but unlike the Army green uniform, no unit patches, specialty tabs, or the black beret were worn. Officers wore their silver or gold-colored rank insignia pinned onto the shoulder epaulets, while enlisted personnel wore gold-on-white rank insignia and service stripes on both sleeves as that on the Army Blue Uniform. A white dress shirt and either a black bow tie or four-in-hand necktie, for formal and semi-formal functions, were worn.
It's definitely an interesting dilemma. When it comes to the medical detachment, I can find no information on the members having any kind of white uniform and it would seem that they wore was pretty much what other members of the unit wore. Here's an informative page about WW2 Hospitals and medical personnel:
The jackets that they wear seem more like lab or work coats and they are not wearing ties as all others are. The trousers seem to be white (although that could be from over exposure due to the white shirts) and the headgear seems to be the same as the other soldiers. It seems as though they are wearing some kind of work uniform so could this be a KP uniform or maybe an Orderly uniform for a hospital? Questions, questions...
Gary