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a statement of conditions commonly observed in a given situation, or of a prescribed procedure to obtain a given result. For specific rules, see specific name, as m'naghten rule.
rule of nines a method of estimating the extent of burns, expressed as a percentage of total body surface. In this method, the body is divided into sections of 9 per cent, or multiples of 9 per cent, each: head and neck, 9 per cent; anterior trunk, 18 per cent; posterior trunk, 18 per cent; upper limbs, 18 per cent; lower limbs, 36 per cent; genitalia and perineum, 1 per cent. The rule of nines is fairly accurate for adults but does not allow for differences in proportion in children, for whom the lund and browder classification is generally used.
Rule of nines.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


A principle, criterion, standard, or guideline, applied to procedures or situations in which accumulated observation is considered relevant.
See also: law, principle, theorem.
[O. Fr. reule, fr. L. regula, a guide, pattern]
Farlex Partner Medical Dictionary © Farlex 2012


Vox populi A statement of the parameters usually associated with a particular condition or state. See Birthday rule, Chambon's rule, Cram-down rule, Discovery rule, Durham rule, Eight-hr rule, Federal Rules of Evidence, Federal Rules of Civil Procedure, Federal medical privacy rule, 55 rule, FFP rule, Frye rule, Gag rule, GU-AG rule, Ingelfinger rule, Haldane's rule, Locality rule, Loser pays rule, Marquis of Queensbury rule, M'Naghten rule, N-end rule, Normal rule, Prudent person rule, Safe harbor rule, Trapezoidal rule.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


A criterion, standard, or guide governing a procedure, arrangement, action, or other process.
See also: law, principle, theorem
[O. Fr. reule, fr. L. regula, a guide, pattern]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


(rool) [Fr. riule fr L. regula, ruler, pattern]
A guide or principle based on experience or observation.

ABCD prediction rule

ABCD score.

ABCD rule

ABCD score.

buccal object rule

A dental radiographical technique used to identify the position of an object within a three-dimensional area. A reference radiograph is taken. The projection angle is changed and the resulting radiograph compared with the reference radiograph. If the image remains in the same position, the object is located buccal to the reference object. If the image changes position, the object is lingual to the reference object.

CHIP rule

A diagnostic prediction rule used to determine if a patient with a minor head injury would benefit from emergent CT imaging of the brain. Low-risk patients are those who have a Glascow Coma Scale (GCS) of 15, and no history of loss of consciousness, amnesia, vomiting, or generalized headache. These patients do not need neuroimaging in the Emergency Department, and can be discharged home with follow-up. Patients who are over 60 years old, or who have a history of alcohol or drug use, epilepsy, or coagulopathy are considered high risk regardless of their GCS. Patients with intermediate findings are considered to have medium-risk mild head injuries.

Cieszynski rule

See: Cieszynski rule

Clark rule

See: Clark rule

Common Rule

Any of the U.S. policies designed to protect the rights and interests of citizens who choose to participate in government-funded biomedical research. Those who choose to participate in biomedical research often suffer from life-altering or life-threatening illnesses. As a result they may be more psychologically vulnerable than others and may agree to become investigative subjects because of fear or desperation. The protections provided by the Common Rule are designed to ensure that agencies that perform federally funded human research respect the rights of experimental subjects. Included are the rights of confidentiality and full disclosure (informed consent). Research performed on children or prisoners is given special protections.

convex-concave rule

, concave-convex rule.
A law of joint kinematics that states that if a convex joint surface moves on a stationary concave surface, the convex joint will slide in the direction opposite that of the angular motion of the bone, and that if a concave joint surface moves on a stationary convex surface, the articular surface will slide in the same direction as the angular motion of the bone.

Cowling rule

See: Cowling rule

decision rule

See: decision aid

Durham rule (of criminal responsibility)

A legal decision from Durham v. United States that limits the culpability of those with psychological or neurological diseases who have committed criminal acts. It states that an unlawful act is not a criminal act if it was committed by someone mentally ill, e.g., psychotic at the time, or was committed by someone with profound neurological disease, e.g., with severe dementia or organic brain injury.

learned intermediary rule

Learned intermediary doctrine.

mature minor rule

Any of the regulations in some states that allow the practitioner to treat minors without parental consent if the minor is deemed to be capable of understanding the nature and consequences of the treatment and if the treatment is of benefit to the minor.

modified Ottawa ankle rules

See: modified Ottawa ankle rules
Enlarge picture

rule of nines

A formula for estimating percentage of body surface areas, particularly helpful in judging the portion of skin that has been burned. For the adult, the head represents 9%; each upper extremity 9%; the back of the trunk 18%, and the front 18%; each lower extremity 18%; and the perineum the remaining 1%.
See: illustration

Ottawa ankle rules

See: Ottawa ankle rules

rule of ten

The criteria used to judge the readiness of an infant for surgical repair of a cleft lip. The infant must weigh 10 lb, be 10 weeks old, have a hemoglobin value of 10 g, and have a white blood cell count less than 10,000.

rule of thirds

The classification of bone shaft fractures: proximal third, midshaft, and distal third. Midshaft fractures heal more slowly than other fractures because the blood supply in the middle of a bone is less than that at either end.

van't Hoff rule

See: van't Hoff, Jacobus Henricus
Medical Dictionary, © 2009 Farlex and Partners


1. A guiding principle governing an action or a procedure.
2. A rigid, graduated rod for measuring length.
Javal's rule A relationship that relates corneal astigmatism to the total astigmatism of the eye. It states that
At = 1.25Ac − 0.50 axis 90º
where At and Ac are the total and corneal astigmatism, respectively. This relationship is relatively accurate in predicting the total astigmatism of the eye when corneal astigmatism is greater than 2D. For smaller amounts of corneal astigmatism, a more appropriate version of Javal's rule is
At = 1.0Ac − 0.50 axis 90º

Kestenbaum's rule A procedure designed to estimate the power of the addition needed to read ordinary newsprint (about Jaeger 5 or N7-8) in low vision patients. It consists of dividing the denominator of the Snellen visual acuity fraction by its numer-ator (i.e. 1/Snellen visual acuity). Example: if the Snellen visual acuity is 6/60 (20/200) the power of the add will be +10D, which corresponds to a magnification of 10/4 = 2.5✕. Syn. Kestenbaum's formula.
Knapp's rule See Knapp's law.
Kollner's rule Lesions of the outer retinal layers and changes in the ocular media produce a blue-yellow colour vision defect, whereas lesions of the inner retinal layers, the optic nerve and the visual pathway produce a red-green defect. Examples: age-related maculopathy causes a blue-yellow defect; optic neuritis causes a red-green defect. There are exceptions to this rule, particularly during the evolution of a disease. Syn. Kollner's law.
near point rule A device for measuring the near points of accommodation and convergence. The RAF rule consists of a graduated four-sided bar on which is mounted a movable target holder which can be moved in the median plane of the head. The bar is calibrated in centimetres and dioptres (Fig. R15). See push-up method.
PD rule A ruler calibrated in millimetres used for measuring the interpupillary distance. Some have the zero point in the middle and the gradations on each side to measure two half-distances thus taking into account facial asymmetry. Many PD rules also have facilities for measuring frames (Fig. R16). Syn. pupillometer (although it is an incorrect use of this term, it is frequently used as a synonym).
Prentice's rule See Prentice's law.
Prince's rule A device for determining the location of the near point of accommodation and the amplitude of accommodation. It consists of a ruler scaled in dioptres on one side and in millimetres on the other. One end of the ruler is held against the face and a test card is moved along the ruler towards the eye until a blur is noticed. The amplitude of accommodation in dioptres represents either the ocular accommodation (if the reference point is the cornea) or the spectacle accommodation (if the reference point is the spectacle plane).
Fig. R15 The RAF near point ruleenlarge picture
Fig. R15 The RAF near point rule
Fig. R16 PD rule. Measurement of the interpupillary distance is made by measuring the distance A between the two corneal images, or B between the edges of the pupils (if both pupils are of the same size), or C between the edges of the limbusenlarge picture
Fig. R16 PD rule. Measurement of the interpupillary distance is made by measuring the distance A between the two corneal images, or B between the edges of the pupils (if both pupils are of the same size), or C between the edges of the limbus

Table R3 Power of the addition required (and corresponding focal length) to read ordinary newsprint (about J5 or N8) in low vision patients, for various acuities. The add is calculated according to Kestenbaum's rule and is an estimate
Acuity at
40 cm
Snellen equivalent
at 40 cm
power of add
focal distance of add
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann


Principle, criterion, standard, or guideline, applied to procedures or situations in which accumulated observation is considered relevant.
[O. Fr. reule, fr. L. regula, a guide, pattern]
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about rule

Q. What she should do, if found positive? my wife who is 31 years, had breast cancer history in her family and I have advised her to have a test. She will have her test done next week. What she should do, if found positive?

A. I think you must pray that she is not positive, but if found positive let the doctor start the treatment and she should cooperate with doctor. She needs to learn about her problem and also the ways to cope them, like by having good diet and fitness, which she would require when the treatment or surgery will be done. Thanks ....and hope she is not positive…

Q. The HIV test came back POSITIVE! My very close friend 'Demonte'. One day in December as he was returning from a business trip, his wife met him at the airport with terrible news. During a routine pregnancy check up, her doctor had administered an HIV test along with other blood-work. The HIV test came back POSITIVE! The doctor wanted to begin administering drugs immediately but the cost of these drugs here when compared to their family income was prohibitive. I helped him with some of my savings. He already sold his favorite sentimental car to save his precious wife. Now i want to know is there any NATURAL medicine to cure this? Hope it costs less and available.

A. there are no effective natural remedy for HIV. the medications are very hard ones that try to control the virus from spreading (cannot eliminate it though). no herbal remedy or nutrition change will do that.

Q. is her2 positive more agressive than her2 negative? i know someone with her2 positive breast cancer and her doctor said it was more difficult to detect upon its return if it came back i want to know if it is true and what can she do to detect it earlier

A. Over-expression of her2/neu, a specific molecule in the breast cancer cell is indeed considered to convey worse prognosis, and suggest the need for chemotherapy and immunotherapy with Herceptin. However, the decision is much more complicated and should be made on case by case basis after consulting a professional.

More discussions about rule
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References in periodicals archive ?
These results were achieved using a linear classifier trained in a 6D feature space consisting of asymmetry score using texture, colour, and shape (for shape asymmetry, instead of intensity values, MSE of the area was computed) (for each of these, asymmetry score corresponding to two axes was computed to mimic ABCD rule).
Although many different techniques are proposed, most of the approaches are mimickers of the clinical ABCD rule of dermoscopy.
In the ABCD rule of dermoscopy [45], for instance, the following six colours are considered important: light brown, dark brown, black, red, white, and blue-grey.
As previously discussed, this is to imitate clinical practices (such as ABCD rule) to quantify colour variegation feature of skin lesions.
Cognetta et al., "ABCD rule of dermatoscopy: a new practical method for early recognition of malignant melanoma," European Journal of Dermatology, vol.
Initial treatment should be based on the ABCD rule, a mnemonic for remembering that younger (aged <55 years) and nonblack patients will respond better to an Angiotensin-converting enzyme inhibitor or a Beta-blocker, and older patients and blacks of any age will respond better to a Calcium-channel blocker or a Diuretic (SOR=C).