Furthermore, any untreated abscess may (and most likely will) continue to expand, eventually becoming a serious systemic infection. Cause
Abscesses are caused by a high-density infection of (usually) common bacteria which collect in one place or another for any variety of reasons. Anal abscesses, without treatment, are likely to spread and affect other parts of the body, particularly the groin and rectal lumen. All abscesses can progress to serious generalized infections requiring lengthy hospitalizations if not treated. Historically, many rectal abscesses are caused by bacteria common in the digestive system, such as E. coli. While this still continues often to be the case, there has recently been an increase in the causative organism being staphylococcus, as well as the difficult to treat community-acquired methicillin-resistant S. aureus. Because of the increasing appearance of more exotic bacteria in anal abscesses, microbiological examination will always be performed on the surgical exudate to determine the proper course of any antibiotic treatment. Diagnosis
Diagnosis of anorectal abscess begins with a medical history and physical exam. Imaging studies which can help determine the diagnosis in cases of a deep non-palpable perirectal abscess include pelvic CT scan, MRI or trans-rectal ultrasound. These studies are not necessary, though, in cases which the diagnosis can be made upon physical exam. Classification
Anorectal abscesses are classified according to their anatomic location and the following are the most common types: perianal abscess, ischiorectal abscess, intersphincteric abscess and supralevator abscess.
Precautions
Women who have experienced vaginal bleeding post menopause, certain cancers, stroke, heart attack, blood clotting, or uncontrollable bleeding, and women who are pregnant or allergic to ingredients in estrogen patches should not use an estrogen patch as serious adverse effects may occur. Society and culture
Brand names
Estrogen patches are available in multiple brand names in different countries. Some patches are available with a progestin such as levonorgestrel, norethisterone acetate, or norelgestromin. See also
Pharmacokinetics of estradiol § Transdermal administration
Hormone replacement therapy

References
External links
"Estradiol". Drug Information Portal. U.S. National Library of Medicine. "Estradiol mixture with levonorgestrel". Drug Information Portal. U.S. National Library of Medicine. "Estradiol mixture with norethindrone acetate". Drug Information Portal. U.S. National Library of Medicine.