Norethisterone, also known as norethindrone and sold under many brand names, is a progestin medication used in birth control pills, menopausal hormone therapy, and for the treatment of gynecological disorders. The medication is available in both low-dose and high-dose formulations and both alone and in combination with an estrogen. It is used by mouth or, as norethisterone enanthate, by injection into muscle.Side effects of norethisterone include menstrual irregularities, headaches, nausea, breast tenderness, mood changes, acne, increased hair growth. Norethisterone is a progestin, or a synthetic progestogen, and hence is an agonist of the progesterone receptor, the biological target of progestogens like progesterone. It has weak androgenic and estrogenic activity, mostly at high dosages, and no other important hormonal activity.Norethisterone was discovered in 1951 and was one of the first progestins to be developed. It was first introduced for medical use on its own in 1957 and was introduced in combination with an estrogen for use as a birth control pill in 1963. It is sometimes referred to as a "first-generation" progestin. Along with desogestrel, it is one of the only progestins that is widely available as a progestogen-only "mini pill" for birth control. Norethisterone is marketed widely throughout the world. It is available as a generic medication. In 2019, it was the 143rd most commonly prescribed medication in the United States, with more than 4 million prescriptions. It is on the World Health Organizations List of Essential Medicines.
Type I – No fistula present

Type IA – Presence of the cystic duct
Type IB – Obliteration of the cystic ductTypes II–IV – Fistula present

Type II – Defect smaller than 33% of the CHD diameter
Type III – Defect 33–66% of the CHD diameter
Type IV – Defect larger than 66% of the CHD diameter

Diagnosis
Imaging by ultrasonography, MRCP, or CT scan usually make the diagnosis. MRCP can be used to define the lesion anatomically prior to surgery. Occasionally Mirizzis syndrome is diagnosed or confirmed on ERCP when requested to alleviate obstructive jaundice or cholangitis by means of an endoscopically placed stent, or when USS has been wrongly reported as choledocolithiasis. Treatment
Simple cholecystectomy is suitable for type I patients. For types II–IV, subtotal cholecystectomy can be performed to avoid damage to the main bile ducts. Cholecystectomy and bilioenteric anastomosis may be required. Roux-en-Y hepaticojejunostomy has shown good outcome in some studies. Epidemiology
Mirizzis syndrome occurs in approximately 0.1% of patients with gallstones. It is found in 0.7 to 2.5 percent of cholecystectomies.It affects males and females equally, but tends to affect older people more often. There is no evidence of race having any bearing on the epidemiology. Eponym
It is named for Pablo Luis Mirizzi (1893–1964), an Argentinian physician. Mirizzi was educated and trained in his hometown and later visited some of the best hospitals throughout the United States for further education and training. Mirizzi specialized in abdominal and thoracic surgery and would write prolifically on related surgical topics. References


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