Dictionary

placenta, supernumerary See placenta, accessory.

placenta, succenturiate See placenta, accessory.

placenta, low See placenta previa.

placenta, accessory A condition in which there is an extra placenta that is separate from the main placenta. Also known as a succenturiate or supernumerary placenta.

placenta A temporary organ that joins the mother and fetus, transferring oxygen and nutrients from the mother to the fetus and permitting the release of carbon dioxide and waste products from the fetus. The placenta is roughly disk-shaped, and at full term it measures about 7 inches in diameter and slightly less than 2 inches…

placebo response A positive medical response to taking a placebo, as if it were an active medication.

placebo A sugar pill or any other inactive substance that is given instead of medication. In a controlled clinical trial, one group may be given a medication and another group a placebo, to learn whether a difference in treatment response is due to the medication, the power of suggestion, or other factors. See also placebo…

PKU, variant A form of phenylalanine hydroxylase deficiency that is more mild than classic PKU and typically causes less intellectual impairment.

PKU, maternal The disease phenylketonuria (PKU) in a pregnant woman whose high blood levels of phenylalanine are dangerous to a developing fetus. High phe can damage a baby before birth. If the mother’s PKU is not controlled, the fetus (which may not have PKU) is at high risk for congenital heart disease, growth retardation, microcephaly,…

PKU Phenylketonuria, a metabolic disease that is due to the inherited inability to process the essential amino acid phenylalanine. The biochemical basis of PKU is complete or near-complete deficiency of the enzyme phenylalanine hydroxylase. Newborns in many countries are now routinely screened for PKU via a blood test. Treatment of PKU involves a special diet…

PKD Polycystic kidney disease.

pityriasis rosea A common mild rash of unknown origin that may last from several weeks to several months, often beginning with a “herald” patch, a large single pink patch on the chest or back and, within a week or so, more pink patches on the torso, arms, and legs. There may be itching, especially when…