Hemolytic disease of the newborn, also known as hemolytic disease of the fetus and newborn, HDN, HDFN, or erythroblastosis foetalis, is an alloimmune condition that develops in a fetus at or around birth, when the IgG molecules (one of the five main types of antibodies) produced by the mother pass through the placenta. Among these antibodies are some which attack antigens on the red blood cells in the fetal circulation, breaking down and destroying the cells. The fetus can develop reticulocytosis and anemia. The intensity of this fetal disease ranges from mild to very severe, and fetal death from heart failure (hydrops fetalis) can occur. When the disease is moderate or severe, many erythroblasts (immature red blood cells) are present in the fetal blood, earning these forms of the disease the name erythroblastosis fetalis (British English: erythroblastosis foetalis). HDFN represents a breach of immune privilege for the fetus or some other form of impairment of the immune tolerance in pregnancy. Various types of HDFN are classified by which alloantigen provokes the response. The types include ABO, anti-RhD, anti-RhE, anti-Rhc, anti-Rhe, anti-RhC, multiantigen combinations, and anti-Kell. Although global prevalence studies of the differential contribution of those types are lacking, regional population studies have shown the anti-RhD type to be the most common cause of HDFN, followed by anti-RhE, anti-RhC, and anti-Rhc. Signs and symptoms
Signs of hemolytic disease of the newborn include a positive direct Coombs test (also called direct agglutination test), elevated cord bilirubin levels, and hemolytic anemia.
When fissures are found laterally, tuberculosis, occult abscesses, leukemic infiltrates, carcinoma, acquired immunodeficiency syndrome (AIDS) or inflammatory bowel disease should be considered as causes. Some sexually transmitted infections can promote the breakdown of tissue resulting in a fissure. Examples of sexually transmitted infections that may affect the anorectal area are syphilis, herpes, chlamydia and human papilloma virus.Other common causes of anal fissures include:

childbirth trauma in women
anal sex
Crohns disease
ulcerative colitis
poor toileting in young children. Diagnosing
External anal fissures on the anal verge can be diagnosed by visual inspection.Internal anal fissures in adults on anterior side, posterior side or within any part of the inner circumference of the anal sphincter muscle can be diagnosed with beak proctoscope 23mm diameter, Chelsea Eaton anal speculum 23mm diameter, Park anal retractor or by digital rectal examination with a finger inside the anal sphincter muscle. Narrow anal fissures might not be felt by finger during rectal examination due to the glove.Note that colonoscopy, sigmoidoscopy, or normal proctoscopy is for diagnosing internal hemorrhoids and other internal rectal diseases and not for diagnosing anal fissures. Prevention
For adults, the following may help prevent anal fissures:

Avoiding straining when defecating. This includes treating and preventing constipation by eating food rich in dietary fiber, drinking enough water, occasional use of a stool softener, and avoiding constipating agents. Similarly, prompt treatment of diarrhea may reduce anal strain. Careful anal hygiene after defecation, including using soft toilet paper and cleaning with water, plus the use of sanitary wipes.