differential diagnosis, 428 evaluation and decision, 428 –430 history and physical examination, 428 pathophysiology, 428 primary, 428 , 430 Polyethylene glycol (PEG), 131 –132 Polymerase chain reaction (PCR), 154 , 200 –202 , 383 , 402 , 431 , 442 , 450 , 460 –461 , 475 , 500 –501 , 504 , 506 –507 , 544 , 892 , 931 , 1343 , 1361 , 1414 Polymerase chain reaction assays, 720 Polymorphous light eruption (PMLE), 435 –436 , 436 f Polymyositis, 560 Polymyxin B, 445 Polythelia, 113 Pompholyx See Dyshidrotic eczema Port-wine stains, 1351 Positive end-expiratory pressures (PEEPs), 50 Positive pressure ventilation (PPV), 49 , 65 Postconcussion syndrome, 119 Posterior cord syndrome, 1249 –1250 Posterior cruciate ligament injuries, 277 Posterior reversible encephalopathy syndrome (PRES), 120 , 191 Posterior uveitis, 189 –190 Postextraction complications alveolar osteitis, 1314 –1315 hemorrhage, 1314 infection, 1314 treatment goals, 1314 Postextraction infection, 1314 Postinfectious arthritis, 406 Postinfectious encephalitis, 892 Postinfectious glomerulonephritis, 982 –983 Postoperative adhesions, 1303 Postpericardiotomy syndrome, 369 Posttonsillectomy hemorrhage (PTH), 1328 clinical recognition, 1328 discharge/admission, clinical indication for, 1329