I Am 73 Years Old Weigh 270 And Am 5,4

I am 73 years old weigh 270 and am 5,4 in. tall....after a transvaginal ultrasound I was advised by my obgyn doctor that I have a thickened endomitrium and that a biopsy is necessary....what type of biopsy should be done? and also what may be the cause of the thickening. Thank you for your response.