#congenital malformation

• Acardia — A congenital absence of the heart or a complete cessation in the ontogenetic development of the cardiac structure in a fetus. This severe structural anomaly is incompatible with independent extrauterine life and is documented almost exclusively within monochorionic multiple pregnancies with asymmetric development (TRAP sequence), where the affected fetus's blood circulation is maintained solely by its twin's heart through placental vascular anastomoses.
• Adactyly — A rare congenital malformation characterized by the total or partial absence of fingers or toes. This structural anomaly of embryonic development can occur in isolation or as part of a complex malformativ syndrome, determined by genetic mutational factors or external teratogenic insults suffered by the embryo during the first weeks of pregnancy.
• Agastria — An extremely rare congenital malformation consisting of the total absence of the stomach from birth; by extension, the anatomical and clinical state resulting from a total gastrectomy (complete surgical removal of the organ). Structurally, this condition disrupts the normal digestive pathway, requiring a surgical restructuring of the tract by directly connecting the esophagus to the jejunum (esophagojejunostomy) and a strict nutritional regimen.
• Amyelencephalus — A medical term from the field of teratology denoting a fetus or congenitally malformed organism structurally characterized by the total absence or severely impaired development of the spinal cord (amyelia) and the myelencephalon (embryonic medulla oblongata). This severe neurological anomaly is incompatible with life and is investigated within major neural tube defects.
• Amyelia — An extremely rare and severe congenital malformation within the neural tube defects spectrum, characterized by the total absence or complete developmental arrest of the spinal cord. This severe structural anomaly occurs during the first weeks of embryogenesis due to the failure of the posterior neuropore to close, being incompatible with extrauterine life and often associated with other major cranial malformations.
• Anencephalic — The feminine form of 'anencefal'; describing an organic structure, a pregnancy, or a female biological entity characterized by the total or partial congenital absence of the brain and cranial vault. The term is frequently utilized in medical imaging and obstetrics to qualify severe malformations detected during fetal morphology scans.
• Anencephaly — An extremely severe, lethal congenital malformation characterized by the total or partial absence of the cerebral hemispheres, cerebellum, and cranial vault, caused by the failure of the anterior neuropore to close during embryogenesis (days 23-26). This major structural condition is incompatible with long-term survival, with most cases resulting in stillbirth or death shortly after birth.
• Aneresis — A rare congenital malformation or structural anomaly characterized by the partial or total absence of the anus, often associated with anal imperforation or the presence of abnormal rectal fistulas. Clinically and functionally, this severe bio-structural condition blocks the normal evacuation of fecal matter in the newborn, requiring emergency reconstructive surgical intervention immediately after birth.
• Aoria — A rare medical term used to describe the congenital absence, severe atrophy, or lack of structural development of the aorta, the primary artery of the human body. This extremely severe pathological phenomenon directly affects the systemic circulation and requires complex surgical intervention immediately after birth to ensure organism survival.
• Apodia — An extremely rare congenital malformation characterized by the complete, unilateral or bilateral, absence of feet or lower limbs at birth; a severe structural anomaly of embryonic development. In teratological practice, this condition is studied in close connection with dysmelia and phocomelia, representing the early developmental arrest of lower limb buds.
• Aproctia — An extremely rare congenital malformation characterized by the complete absence, imperforate state, or congenital structural occlusion of the anal orifice (anus). This anatomical phenomenon requires emergency pediatric surgical intervention immediately after birth to create an artificial elimination pathway and restore normal physiological functions.