Dictionary

pneumothorax Free air in the chest outside the lung. Pneumothorax can occur spontaneously, follow a fractured rib or other trauma, occur in the wake of chest surgery, or be deliberately induced in order to collapse the lung.

PNL Percutaneous nephrolithotripsy.

PNS Peripheral nervous system.

p.o. Per os. Abbreviation meaning by mouth, orally. See also Appendix A, “Prescription Abbreviations.”

podiatrist A specialist in the diagnosis and care of foot disorders, including their medical and surgical treatment.

poikiloderma Extra pigmentation of the skin that demonstrates a variety of shades and is associated with widened capillaries (telangiectasia) in the affected area.

poikiloderma congenita See RothmundThomson syndrome.

point, McBurney See McBurney point.

point mutation A single nucleotide base change in DNA. For example, a point mutation is the cause of sickle cell disease.

poison Any substance that can cause severe organ damage or death if ingested, breathed in, or absorbed through the skin. Many substances that normally cause no problems, including water and most vitamins, can be poisonous if taken in excessive quantity. Poison treatment depends on the substance.

poison control center A special information center set up to inform people about how to respond to potential poisoning. These centers maintain databases of poisons and appropriate emergency treatment. Local poison control centers should be listed with other community-service numbers in the front of the telephone book, and they can also be reached immediately through…

poison ivy Skin inflammation that results from contact with the poison ivy vine. Chemicals produced by this vine cause an immune reaction, producing redness, itching, and blistering of the skin. Treatment involves use of topical medications.