Electromyography, Pelvic Floor Sphincter

Electromyography, Pelvic Floor Sphincter

Synonym/acronym: Electrodiagnostic study, rectal electromyography.

Common use

To assess urinary sphincter electrical activity to assist with diagnosis of urinary incontinence.

Area of application

Sphincter muscles.




Pelvic floor sphincter electromyography, also known as rectal electromyography, is performed to measure electrical activity of the external urinary sphincter. This procedure, often done in conjunction with cystometry and voiding urethrography as part of a full urodynamic study, helps to diagnose neuromuscular dysfunction and incontinence.

This procedure is contraindicated for

  • high alert Patients with bleeding disorders because the puncture sites may not stop bleeding.


  • Evaluate neuromuscular dysfunction and incontinence

Potential diagnosis

Normal findings

  • Normal urinary and anal sphincter muscle function; increased electromyographic signals during the filling of the urinary bladder and at the conclusion of voiding; absence of signals during the actual voiding; no incontinence

Abnormal findings related to

  • Neuromuscular dysfunction of lower urinary sphincter, pelvic floor muscle dysfunction of the anal sphincter

Critical findings


Interfering factors

  • Factors that may impair the results of the examination

    • Inability of the patient to cooperate or remain still during the procedure because of age, significant pain, or mental status.
    • Age-related decreases in electrical activity.
    • Medications such as muscle relaxants, cholinergics, and anticholinergics.
  • Other considerations

    • Failure to follow dietary restrictions before the procedure may cause the procedure to be canceled or repeated.

Nursing Implications and Procedure


  • Positively identify the patient using at least two unique identifiers before providing care, treatment, or services.
  • Patient Teaching: Inform the patient this procedure can assist in measuring the electrical activity of the pelvic floor muscles.
  • Obtain a history of the patient’s complaints or clinical symptoms, including a list of known allergens, especially allergies or sensitivities to latex, anesthetics, or sedatives.
  • Obtain a history of the patient’s genitourinary system, symptoms, and results of previously performed laboratory tests and diagnostic and surgical procedures.
  • Obtain a list of the patient’s current medications, including herbs, nutritional supplements, and nutraceuticals (see Effects of Natural Products on Laboratory Values online at DavisPlus).
  • Review the procedure with the patient. Address concerns about pain related to the procedure. Warn the patient the procedure may be uncomfortable, but an analgesic or sedative will be administered. Assure the patient the pain is minimal during the catheter insertion. Inform the patient the procedure is performed in a special laboratory by a health-care provider (HCP) and takes about 30 min to complete.
  • Sensitivity to social and cultural issues, as well as concern for modesty, is important in providing psychological support before, during, and after the procedure.
  • Instruct the patient to remove jewelry and other metallic objects from the area to be examined.
  • Assess for ability to comply with directions given for exercising during the test.
  • Under medical direction, the patient should avoid muscle relaxants, cholinergics, and anticholinergics for 3 to 6 days before the test.
  • Instruct the patient to abstain from smoking and drinking caffeine-containing beverages for 3 hr before the procedure. Protocols may vary among facilities.
  • Make sure a written and informed consent has been signed prior to the procedure and before administering any medications.


  • Potential complications:
  • Complications are rare but include bleeding related to a bleeding disorder, or the effects of natural products and medications known to act as blood thinners and urinary infection related to use of a catheter.

  • Observe standard precautions, and follow the general guidelines in Patient Preparation and Specimen Collection. Positively identify the patient.
  • Ensure the patient has complied with dietary, fluid, tobacco, and medication restrictions and pretesting preparations.
  • Record baseline vital signs.
  • Instruct the patient to void prior to the procedure and to change into the gown, robe, and foot coverings provided.
  • Avoid the use of equipment containing latex if the patient has a history of allergic reaction to latex.
  • Place the patient in a supine position on the examining table and place a drape over the patient, exposing the perianal area.
  • Ask the patient to remain very still and relaxed and to cooperate when instructed to contract muscles during the procedure.
  • Two skin electrodes are positioned slightly to the left and right of the perianal area and a grounding electrode is placed on the thigh.
  • If needle electrodes are used, they are inserted into the muscle surrounding the urethra.
  • Muscle activity signals are recorded as waves, which are interpreted for number and configurations in diagnosing urinary abnormalities.
  • An indwelling urinary catheter is inserted, and the bulbocavernosus reflex is tested; the patient is instructed to cough while the catheter is gently pulled.
  • Voluntary control is tested by requesting the patient to contract and relax the muscle. Electrical activity is recorded during this period of relaxation with the bladder empty.
  • The bladder is filled with sterile water at a rate of 100 mL/min while the electrical activity during filling is recorded.
  • The catheter is removed; the patient is then placed in a position to void and is asked to urinate and empty the full bladder. This voluntary urination is then recorded until completed. The complete procedure includes recordings of electrical signals before, during, and at the end of urination.


  • Inform the patient that a report of the results will be made available to the requesting HCP, who will discuss the results with the patient.
  • Instruct the patient to resume usual diet, fluids, medications, and activity, as directed by the HCP.
  • Monitor vital signs and neurological status every 15 min for 1 hr, then every 2 hr for 4 hr, and as ordered. Take temperature every 4 hr for 24 hr. Monitor intake and output at least every 8 hr. Compare with baseline values. Protocols may vary among facilities.
  • Instruct the patient to increase fluid intake unless contraindicated.
  • If tested with needle electrodes, warn female patients to expect hematuria after the first voiding.
  • Advise the patient to report symptoms of urethral irritation, such as dysuria, persistent or prolonged hematuria, and urinary frequency.
  • Recognize anxiety related to test results, and be supportive of perceived loss of independent function. Discuss the implications of abnormal test results on the patient’s lifestyle. Provide teaching and information regarding the clinical implications of the test results, as appropriate.
  • Reinforce information given by the patient’s HCP regarding further testing, treatment, or referral to another HCP. Answer any questions or address any concerns voiced by the patient or family.
  • Depending on the results of this procedure, additional testing may be needed to evaluate or monitor progression of the disease process and determine the need for a change in therapy. Evaluate test results in relation to the patient’s symptoms and other tests performed.

Related Monographs

  • Related tests include CT pelvis, cystometry, cystoscopy, cystourethrography voiding, IVP, and US bladder.
  • Refer to the Genitourinary System table at the end of the book for related tests by body system.
Handbook of Laboratory and Diagnostic Tests, © 2013 Farlex and Partners
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