The important charts to be considered for medical astrology are given below:
a) The Rashi chart: This is the main horoscope also known as birth charts. Every divisional chart is derived from this main chart only.
b) The Drekkana Chart: Drekkana is crucial in medical astrology as many a times it provides the knowledge about the exact place of ailments. In Drekkana each sign is divided into three parts of 10 degrees. The first part belongs to the sign itself, the second to the sign falling in the fifth house, the third to the sign falling in the ninth house. Following table will explain it.
22nd Drekkana from the ascendant is very important in medical astrology. Dasa of planets placed in the 22nd Drekkana or evil transits on 22nd Drekkana can trigger health hazards. Likewise, Pasha drekkana i.e., second drekkana of Scorpio can also cause adverse situations in life including Capital punishments. These drekkana positions has to be carefully analysed both for health and longevity analysis.
c) The Navamsha Chart: This is the most important sub-division. Each sign is divided into 9 equal parts of 3 degree 20 minutes. In moveable signs (signs 1,4,7,10) the first Navamsha belongs to be the same sign while the following ones follow in regular order. In fixed signs (2,5,8,11) the first Navamsha falls in the sign ninth from it. In case of dual signs (3,6,9,12) the first Navamsha falls in the sign fifth from it. According to Parashara Navamsha has to be given similar consideration as birth chart for all analysis.
d) The Dwadashamsha chart: This chart is normally analysed to know about one’s parents. However, this chart is also important for medical astrology as it can help to find any inherited disease. Each sign is divided into twelve equal parts of 2 degree 30 minutes. The first Dwadashamsha belongs to the same sign remaining signs follow subsequently. The table below explains it.
The Trishamsha Chart: This chart is generally seen to find out arishta (adverse) indications in the horoscope. In case of Trishamsha, in an odd sign first five degree belong to Mars, the next five degree belongs to Saturn, the next eight degrees belong to Jupiter, the next seven degree belongs to Mercury and the next five degrees belong to Venus. The order gets reversed in even signs. Here, the first five degree belong to Venus, the next seven degree to Mercury, the next eight degree to Jupiter, the next five degree to Saturn and next five degree to Mars.
Other divisional charts which may need to used for medical astrology sometimes. For example, Saptamsha to know about children, both for judging prospects of having children as well as happiness from children. Dwadashamsha can be referred for checking health of parents and drekkana can be seen for seeing the health prospects of brother. The Karaka of father Sun, of mother Moon, of brother Mars, of children Jupiter etc also needs to be checked in the birth chart and respective divisional charts for proper analysis.
Many times, the reason for complicated health problem is pregnancy-related complications. This leads to hospitalization as well. Therefore, for pregnancy related questions it is always safe to cross-check from the Saptamsha.
The Saptamsha chart: If a sign is divided into 7 equal parts, one division is four degree 17 minutes and 8.57 seconds approximately. The counting of the Saptamsha commences from the same sign in the case of odd signs like Aries; it commences from the seventh sign in the case of even signs like Taurus etc.