| Meaning | ||
| Fx | fracture | |
| FA | Fanconi anemia | |
| FAMMM syndrome | familial atypical multiple mole melanoma syndrome | |
| FANA | fluorescent antinuclear antibody test | |
| FAP | familial adenomatous polyposis | |
| FAST | focused assessment with sonography for trauma | |
| FB | foreign body | |
| FBC | Family Birth Center full blood count | |
| FBE | full blood exam | |
| FBG | fasting blood glucose | |
| FBS | Failed back syndrome fasting blood sugar | |
| F/C | fevers and/or chills | |
| F/C/S | fevers and/or chills and/or sweating | |
| FCS | Faciocutaneoskeletal syndrome | |
| FDC | follicular dendritic cellsfixed dose combination | |
| FDG | fluordeoxyglucose | |
| FDIU | fetal demise in utero | |
| FDP | fibrin degradation product Flexor digitorum profundus | |
| FDS | Flexor digitorum superficialis | |
| Fe | iron | |
| FEF25–75 | forced expiratory flow at 25–75% of forced vital capacity | |
| fem | female femoral | |
| FEN | Fluids, Electrolytes, Nutrition | |
| FEP | free erythrocyte protoporphyrin fibroepithelial polyp | |
| FESS | functional endoscopic sinus surgery | |
| FET | frozen embryo transfer | |
| FEV1 | forced expiratory volume in 1 second | |
| FF | free fluids (non-thickened fluids) | |
| FFA | free fatty acids | |
| FFP | fresh frozen plasma | |
| FHR | fetal heart rate | |
| FHS | fetal heart sound | |
| FHT | fetal heart tones | |
| FHx | family history (in medicine, meaning specifically the medical histories of family members and ancestors) | |
| FIBD | found in bed dead | |
| FISH | fluorescence in situ hybridization | |
| FL | femur length | |
| FLAIR | fluid attenuated inversion recovery | |
| FLK | funny-looking kid (slang reference to dysmorphic features) | |
| fl.oz. | fluid ounce (1 Imperial fluid ounce ≈ 28.4 mL; 1 U.S. fluid ounce ≈ 29.6 mL) (use of these units is generally deprecated in modern medicine in favor of mL) | |
| FM | fetal movement | |
| FMF | fetal movements felt | |
| FMP | first menstrual period (that is, menarche) | |
| FMPP | Familial male precocious puberty | |
| fMRI | functional magnetic resonance imaging | |
| FMS | Fibromyalgia Syndrome | |
| F→N | finger-to-nose test (one simple clinical test of motor coordination) | |
| FNA | fine-needle aspiration | |
| FNAB | fine-needle aspiration biopsy | |
| FNAC | fine-needle aspiration cytology | |
| FNC | full nursing care | |
| FND | Functional neurologic disorder | |
| FNH | focal nodular hyperplasia | |
| FOB | Foot of Bed, father of baby, Fiberoptic Bronchoscopy | |
| FOBT | fecal occult blood test | |
| FOF | found on floor (patient fell out of bed)FOP Fibrousdysplasia ossificans progressiva | |
| FOS | full of stool | |
| FOOSH | fall on outstretched hand | |
| FP | Family Planning | |
| FPG | fasting plasma glucose | |
| FRDA | Friedreich's ataxia | |
| FROM | full range of motion | |
| FSBS | finger-stick blood sugar (one method of blood glucose monitoring) | |
| FSE | fetal scalp electrode | |
| FSGS | focal and segmental glomerulosclerosis | |
| FSH | follicle-stimulating hormone | |
| FSIQ | full scale intelligence quotient (Wechsler Intelligence Scale for Children) | |
| FTA | fluorescent treponemal antibody (see syphilis) | |
| FTA-ABS | fluorescent treponemal antibody absorption (see syphilis) | |
| FtM | Female to Male transgender person (Trans Man) | |
| FTT | failure to thrive | |
| F/U | follow-up | |
| FUE | Follicular Unit Extraction | |
| FUT | Follicular Unit Transplantation | |
| FUO | fever of unknown origin | |
| FVC | forced vital capacity (spirometry test value used in assessment of chronic obstructive pulmonary disease) | |
| FWB | full weight bearing, fetal wellbeing | |
| FWD | full ward diet; forward | |
| Fx | fracture; fraction | |
| fxn | function |