Right - Displayed in the Turkish National Army Museum, a high quality Army Doctors uniform, dating from around 1909.
Four shoulder cords are seen in a 1911 Italian Army manual showing the rank insignia for medical officers (from the 1911-1912 Italo-Turkish War period), illustrating the higher grades, and the medical administration:
It should be noted that the original 1876 rank system for medical officers only had three ranks in addition to the 'Doctor-General', and these were:
Right - An 1876 Silver Imperial Army tunic buttons used by Army Medical Officers. Back marks: A.MAYER & CO WIEN; as well as the French pre-war company T.W&W PARIS.
Above - The doctors tunic likely had these buttons had these buttons fitted from 1909 into the WW1 period.
Right - A pair of WW1 war–time Ottoman imperial army BINBASI (Major): medical officers' shoulder boards.
Right (and Below-Right) - It appears that by the mid-war doctors were wearing the 'snake & vine' badge on the shoulder-board (it originally was worn on the black pre-war collars).
A critical reviewed made at the onset of WW1 identifying, that the – "Army Medical Services in Turkey is in an exceedingly backward state" (British 1916 Turkish Army Handbook, p88).
The wartime expansion of the medical service necessitated the major change in rank insignia used by lower grade medical officers, and led to the creation of the new undocumented insignia illustrated in the previous groups for the reorganized administrative officers (around the WW1 period). which appears to show the beginnings of these type of shoulder boards being migrated to the medical branch.
Right - This medical officer wears post-1916 collar piping and a german version of the medical badge on his collar (where the usual Ottoman officers' medical collar patch whould have been worn).
From 1909, the Ottoman Army Medical Branch Doctors had black collars with the Ottoman version of the Aesculapian Snake badges, and Pharmacists wore a bay leaf badge (again of Ottoman design), on their black collars. In the field, Medical officers wore an Ottoman Red Crescent Society arm band. From 1916, the colour of the collars were changed to:
The adoption of different colour branch of service collars in 1916, probably helped reduce any confusion in ranks (due to the fact that lower grade administrative officers used the exact same shoulder cords and rank stars as upper-grade medical captains). The collar was full coloured, or was same colour as the uniform but with a Blood Velvet cloth piping (Medical), or Nut Green Velvet (Pharmacists), along the edge. As well, in some cases the Doctors wore a German version of the Aesculapian Snake badge on the collar (this is pictured on the right). This may be a German Medical officer as large numbers were assigned to the Ottoman Army Medical Branch during the war. Medical Branch officers were appointed with the three ranks:
During WW1, the expansion of the Ottoman Army Medical Branch, saw the establishing of two more grades of officers:
Right - A 'new' group of shoulder boards appeared during the war with silver-tape/cord borders (Figures below). Likely indicating more junior-level medical personnel (yet again while appearing in period photographs, there is no documentation for these, as yet discovered).
Right - Medical Academy students who were yet to graduate, but had good employment records were sent to the war front, as Medical Zabit Vekili’ (Sub-Lieutenant). They wore Blood Velvet cloth shoulder boards edged in silver tape, with the Ottoman or German versions of the Aesculapian Snake badges mounted on these (this is pictured on the right).
Above/Right - Extracted from a WW1 American Colony photograph of a Turkish Red Crescent medical field post, note in particular:
The British 1916 Turkish Army Handbook, describes the Ambulance, or Bearer Company (called "Sanitary Detachments", p.88) allotted one to every Army Division. Added to which are a certain number of men trained in ambulance work. The bearer company contains:
Right - An anbulance field carrier.
Right - This version (seen in Melbourne, Australia, 2016), has the number '393' painted near the red crescent.
Below - A comparison between the IWM and Australian examples, here a brass plate star and crescent has been superimposed over the German Red Cross emblem.
Right - Ottoman Red Crescent Society Doctors and Officials wore a red crescent on white collar patches.
Five basic rank levels can be identified from photographs:
A study on the Ottoman Ottoman Red Crescent Organizaton in WW1 shows typically, the Society had Provincial Centres, as well as sent ‘Health Committees’ to various fronts to organise hospitals etc.
These were composed of volunteer doctors, trained male as well as female nurses, and employed various grades of cashiers/secretaries, as well as an executive officer administratively leading the mission. Five such ranks are mainly identified :
The various 'Health Committees', were given numbered identifiers - such as the: "Towards the end of 1916, the first health committee moved to Sivas, which was an important center on the route to Eastern front.” 
Left - Another activity of the Ottoman Red Crescent Society during the war, was to hire ships for transporting wounded and sick soldiers . An Ottoman Red Crescent Society Steamer: This white painted ‘Ottoman Red Crescent Society’ steamer has the red crescent pained on the ship’s above the waterline (as a warning) the submarines – as they would be aiming at the ship’s centre-point. As well, both funnels in accordance with international shipping rules display the red crescent on a white funnel, as the ship’s shipping livery.
    Husnu Ada (2004) The First Ottoman Civil Society Organizaton in the Service of The Ottoman State: The Case of the Ottoman Red Crescent (Osmanlı Hilal-i Ahmer Cemiyeti) (Sabancı University, September 2004).
Below - A pre-WW1 Ottoman Red Crescent Society armband.
Right - Extracted from a 1915 American Colony photograph the US and Turkish National flags can be seen in the background).
In 1914-15, in Palestine, the American Colony assumed a more crucial role in humantarian efforts for the local populace.
The Turkish military commanders governing Jerusalem trusted the American Colony, as humanitarian neutrals under international Red Cross rules.
The Colony was permitted to continue its relief efforts even after the United States entered the war on the side of the Allies in the spring of 1917.
Right – The 1332-1333 (1914-1915), the Ottoman Red Crescent Society qualification badge for military nursing (this was fitted was a pin back).
Dr. Besim Omer Pasha, in 1911 personally trained daughters of well-known Muslim families in Constantinople in a six-month long volunteer nursing course (who on graduating received a diploma from the Ottoman Red Crescent Society). The 1911 course allowed the first women nurses to give medical care for wounded soldiers.
During the years 1913-14, Dr. Besim Omer Pasha, organized nursery training courses for ordinary women.
Right – A Library of Congress: American Colony Photograph, of a German nun in the Ottoman Red Crescent Society. Likely belonging to an order such as the Borromaerinnen, who had a large convent in Jerusalem. They provided an Ottoman Imperial Army Nursing Contingent.
In April 1917 , the American Colony volunteered to administer six Turkish military hospitals in Jerusalem. Leading to the formation of the ‘The American Colony Nurses’.
Traditionally, in Ottoman society mothers, wives, sisters, and relatives of the sick spontaneously acted as nurses . They were allowed to coming into Imperial Army barracks to help tend to sick or injured soldiers.
Within the Imperial Army’s hospital system there were male nurses/medical orderlies called KAYYUM  .
 Husnu Ada (2004) The First Ottoman Civil Society Organizaton in the Service of The Ottoman State: The Case of the Ottoman Red Crescent (Osmanlı Hilal-i Ahmer Cemiyeti) (Sabancı University, September 2004).
 Nil Sari in The New History of Medicine Studies, 2-3, Istanbul, 1996-97, pp. 11-64.
 British General Staff. (1995) 1916 Handbook of the Turkish Army. Battery Press, Nashville.
 Due to manpower shortages in WW1, it is likely that these soldiers were replaced by soldiers who were in a Penal Battalion.