Mechanical intestinal obstruction, 87 Mechanical obstruction, 87 Mechanical ventilation, 50 , 84 Meckel’s diverticulum, 213 , 218 –220 , 358 , 552 –553 , 1306 , 1306 f Medial clavicle fractures, 1284 Medial collateral ligament (MCL) injuries, 277 Medial epicondyle fractures, 1188 –1189 , 1189 f Mediastinal mass, 320 Medical illness, screening tests, 1429 t Medroxyprogesterone injections, 343 Megaloblastic anemia, 417 Meige disease (lymphedema praecox), 164 Melanocytic lesions, 466 Melanoma, 466 Melanotic neuroectodermal tumor, 351 , 351 f Melena, 213 Membranoproliferative glomerulonephritis (MPGN), 982 Ménière disease, 159 Meningitis, 202 , 1387 , 1387 t, 1389 Meningococcemia, 233 Meningoencephalitis, 891 Meninscus sign, 1413 Menometrorrhagia, 536 Menstrual cycle, normal, 535 –536 Mental impairment, 120 Mesenteric cysts, 1307 –1308 Mesenteric lymphadenitis (ML), 744 Metabolic acidosis, 121 , 482 , 570 , 970 , 972 –973 , 976 –978 , 977 t, 1035 , 1042 , 1044 –1048 , 1050 , 1052 , 1054 Metabolic alkalosis, 121 , 978 , 978 t Metabolic disorders, 333 –337 , 336 t, 1177 Metabolic emergencies aminoacidopathies, 874 carbohydrate disorders, 878 emergency therapy, goals of, 862 fatty acid oxidation defects, 877 –878 inborn errors of metabolism (IEMs), 862 –864 , 863 t–867 t