Gender Identification Using Pelvic Bone

Gender identification is an important aspect, especially when information relating to the deceased is unavailable. It is vital to record the death of the person. The first priority in the process of investigating the sex of the person by the forensic investigator is to determine the sex of the deceased individual.

Sex determination is done during the case of death due to natural disaster, mass disaster, unidentified body, completely decomposed, mutilated, or fragmented body. In situations where sex cannot be identified from the general appearance, microscopic examination, hormone assay, or gonadal biopsy, determination from various bones of the skeleton is conducted.

Gender Identification from bones can be estimated using various features of long bones, skull, and pelvic bones. The most reliable bone used is the pelvic as it is the most sexually dimorphic region of the skeleton. The difference exists because of the crucial role the pelvic plays in the process of pregnancy and birth-giving in females. The accuracy of sex determination from the pelvic bone is placed above 95%.

Difference Between Male and Female Pelvic Bone

• Generally, the male pelvis is heavier, rough with prominent muscle impressions, and the female pelvis is light, smooth, and has less prominent muscle impressions. 
• PUBIC SYMPHYSIS, It is the cartilaginous joint having the fibrocartilaginous interpubic disc located between the left and right pubic bones near the midline of the body and is found to be higher in males and lower in females.
• In males, the body of the pubis is narrow and triangular when compared to females who have much broad and square pubic bones.
• PELVIC INLET is heart-shaped in males and circular/oval-shaped in females and the PELVIC OUTLET  is smaller in males and larger females.
• The SUB-PUBIC ANGLE / PUBIC ARCH is narrow, v-shaped, and less than 90 degrees in males and wide, u-shaped, rounded, broader, and greater than 90 degrees in females.
• CHILOTIC LINE PELVIC PART & CHILOTIC LINE SACRAL PART is found to be 63 mm and 65.5 mm in males and 67.3 mm and 55.6 mm in females respectively.
• PREAURICULAR SULCUS and POSTAURICULAR SULCUS are the most frequent, better developed and with a sharper auricular surface edge in females and are not frequent in males. The postauricular space is narrow in males and wide in females.
• OBTURATOR FORAMEN is large, oval in males and small, triangular in females.
• SACRUM is found to be longer and narrower in males whereas it is much broader and shorter in females.
• ACETABULUM  is large, directed laterally, in males and small and directed anterolaterally in females. The vertical diameter and transverse diameter of the acetabulum are found to be 51.8 mm and 51 mm in males and 43.6mm and 42.9 mm in females respectively. The acetabulosymphsis distance is 56.1 mm in males and 61.4 mm in females
• ISCHIOPUBIC RAMI is slightly everted in males and strongly everted in females. The medial aspect of the ischiopubic ramus is broad and flat in the case of males and in females, it is found to be narrow and crest-like. The ischial tuberosity is inverted in males and everted in females. The mean ischial length is about 83 mm for males and 76 mm for females.
• The GREATER SCIATIC NOTCH is smaller, narrower, deeper in males with the sciatic notch index of 4 to 5 and larger, wider, shallower in females having the sciatic notch index of 5 to 6.
• ILIUM in males are high, tends to be vertical and the mean iliac breadth is 143.5 mm whereas in females, it is lower, laterally divergent and the mean iliac breadth is 137.8 mm. ILIAC TUBEROSITY is large, and not pointed in males and small or absent and pointed mostly in females. The SACROILIAC JOINT in males is larger and smaller in females. 

Conclusion

The pelvis is considered to be the best indicator of gender due to the sexual dimorphism in the morphology related to parturition.

Among many different traits that are used to estimate the sex of the individual, 3 main traits which were originally described by Phenice in the year 1969 namely, subpubic angle, medial aspect of the ischiopubic ramus, and the ventral arch is the most accurate and utilized.

Other morphological traits are found to be more objective with metric analyses or geometric morphological approaches. Studies also indicated that the pelvis is the most suitable bone that can be used for gender identification as its precision and accuracy is in no way affected by age.