In contrast, a study utilizing 3-D ultrasonography to document the prevalence of the arcuate uterus in a gynecological population found no evidence of increased risk of reproductive loss; in this study 3.1% of women had an arcuate uterus making it the most common uterine anomaly; this prevalence was similar than in women undergoing sterilization and lower than in women with recurrent pregnancy loss. Cause
The uterus is formed during embryogenesis by the fusion of the two Müllerian ducts. During this fusion a resorption process eliminates the partition between the two ducts to create a single cavity. This process begins caudally and advances cranially, thus an arcuate uterus represents an in the final stage incomplete absorption process. Diagnosis
A transvaginal ultrasound can reveal the condition. Helpful techniques to investigate the uterine structure are transvaginal ultrasonography and sonohysterography, hysterosalpingography, MRI, and hysteroscopy. More recently 3-D ultrasonography has been advocated as an excellent non-invasive method to delineate the condition. Differential diagnosis
The major differential diagnosis is the uterine septum. The lack of agreement to separate these two entities makes it difficult to assess the results in the literature. Management
Many patients with an arcuate uterus will not experience any reproductive problems and do not require any surgery. In patients with recurrent pregnancy loss thought to be caused by an arcuate uterus hysteroscopic resection can be performed. Epidemiology
Most studies of uterine malformations are based on populations of women who have experienced a miscarriage and thus do not address the issue of the prevalence in the general population. A screening study by Woelfer et al.
No strong evidence supports the idea that higher concentrations of benzoyl peroxide are more effective than lower concentrations. Mechanism of action
Classically, benzoyl peroxide is thought to have a three-fold activity in treating acne. It is sebostatic, comedolytic, and inhibits growth of  Cutibacterium acnes, the main bacterium associated with acne. In general, acne vulgaris is a hormone-mediated inflammation of sebaceous glands and hair follicles. Hormone changes cause an increase in keratin and sebum production, leading to blocked drainage. C. acnes has many lytic enzymes that break down the proteins and lipids in the sebum, leading to an inflammatory response. The free-radical reaction of benzoyl peroxide can break down the keratin, therefore unblocking the drainage of sebum (comedolytic). It can cause nonspecific peroxidation of C. acnes, making it bactericidal, and it was thought to decrease sebum production, but  disagreement exists within the literature on this.Some evidence suggests that benzoyl peroxide has an anti-inflammatory effect as well. In micromolar concentrations it prevents neutrophils from releasing reactive oxygen species, part of the inflammatory response in acne. Side effects
Application of benzoyl peroxide to the skin may result in redness, burning, and irritation. This side effect is dose-dependent.Because of these possible side effects, it is recommended to start with a low concentration and build up as appropriate, as the skin gradually develops tolerance to the medication. Skin sensitivity typically resolves after a few weeks of continuous use.