Webster's New World Medical Dictionary

slipped capital femoral epiphysis
A condition
in which the growth plate of the femur is pushed out
of position, causing hip pain, stiff gait, and some-
times knee pain. Abbreviated SCFE. SCFE is most
common in overweight teenagers. Treatment
involves orthopedic surgery to bring the bone back
into alignment.
slipped disk
See 
herniated disk.
slow virus
A virus that has a long incubation
period before the onset of a very gradual progres-
sive disease. Typically, the diseases caused by slow
viruses affect the central nervous system and are
associated with a variety of nervous system symp-
toms while having a characteristically protracted,
progressive clinical course.
sludge, biliary
See 
biliary sludge.
small for gestational age
In a full-term infant,
weighing 2,500 g or less at birth. Abbreviated SGA.
Infants who are SGA are considered to have
intrauterine growth retardation, given their gesta-
tional age. By contrast, an infant may weigh 2,500 g
or less simply because of prematurity.
small intestine
See 
intestine, small.
small-cell lung cancer
An aggressive type of
lung cancer in which the cancerous cells appear
smaller under a microscope than those in the other
common forms of lung cancer (non-small-cell lung
cancer) and have a characteristic microscopic
appearance. Treatment options for small cell cancer
may be different than for other types of lung cancers
(non-small cell lung cancers) Small-cell lung can-
cer cells have been described as resembling oats
when examined under the microscope. Also known
as oat-cell lung cancer. See also 
non-small-cell
lung cancer.
smallpox
A highly contagious and frequently fatal
viral disease that is characterized by a biphasic fever
and a distinctive skin rash that leaves pock marks in
its wake. Because of its high case-fatality rates and
transmissibility and because people haven’t been
vaccinated against it in years, smallpox now repre-
sents a serious bioterrorist threat. The disease is
caused by the variola virus. The incubation period is
about 12 days (range: 7–17 days) following expo-
sure. Initial symptoms include high fever, fatigue,
headaches, and backaches. A characteristic rash,
most prominent on the face, arms, and legs, follows
in 2 to 3 days. The rash starts with flat red lesions
that evolve in 2 to 3 days. Lesions become pus-filled
and begin to crust early in the second week. Scabs
develop and then separate and fall off after about 3
to 4 weeks. The majority of patients with smallpox
recover, but death occurs in up to 30 percent of
cases. Smallpox is spread from one person to