When it comes to bowel disorders, there is significant overlap among various medical fields. Anorectal manometry (ARM) is a diagnostic tool used in the determination of bowel disorders such as chronic constipation and fecal incontinence. Gastroenterologists commonly administer ARM tests, but should OBGYN physicians offer anorectal manometry as well?
Anorectal manometry (ARM) is a diagnostic test that is used to assess bowel function in patients experiencing chronic constipation or fecal incontinence. ARM is performed by inserting a small balloon (attached to a catheter) directly into the patient’s rectum. The balloon is inflated and measurements such as sphincter strength, rectal sensation, bowel reflexes, and the movements of rectal and anal muscles are acquired.
A series of tests comprise ARM. Anal sphincter electromyography can be performed with surface electrodes to measure sphincter strength. To determine anorectal rest and squeeze pressure, a 4-channel radial air-charged anorectal catheter is used. For the determination of rectal volume, a rectal balloon is inserted into the patient’s rectum and it is slowly filled with water while rectal sensation is assessed. Rectal sensations that are determined include volume required for urge to defecate and maximum tolerable rectal volume.
Rectoanal inhibitory reflex can also be measured, which determines the transient relaxation of the internal anal sphincter relative rectal distention. Another measurement is rectoanal inhibitory reflex which determines transient relaxation of internal anal sphincter in comparison to rectal distension. A balloon expulsion test may also be performed, which assesses anorectal dysfunction.
Anorectal Manometry in Obstetrics / Gynecology
Although ARM is most commonly associated with gastroenterology or urology, there is utility for this diagnostic test in OBGYN practices, as well. Here, two case studies will be presented.
Anorectal Manometry in Women with Stress Urinary Incontinence
In one prospective study1, anorectal manometry was performed in women with urodynamically proven genuine stress urinary incontinence (SUI) to determine whether manometric variables could predict the development of pelvic organ prolapse following Burch colposuspension, which is often performed following cesarean section in women diagnosed with SUI prior to pregnancy.
For this study, 21 women with proven stress urinary incontinence who had also undergone a Burch colposuspension, as well as 44 healthy control individuals, underwent anorectal manometry. A standardized questionnaire regarding bowel function was also administered. For patients that had received colposuspension, the test and questionnaire were given one year following surgery.
Prior to colposuspension surgery, 62% of women with SUI had fecal incontinence, 38% experienced constipation, and 71% experienced straining at defecation. There were no significant changes in manometric parameters for women with SUI either before or after colposuspension surgery.
For the 6 patients that had prolapse surgery following Burch colposuspension, a significantly lower anal squeeze pressure area was evident preoperatively, relative to control subjects. For the 15 patients that did not develop pelvic organ prolapse, there were no differences in manometric parameters prior to surgery than in the control subjects.
This study has two conclusions: one, that bowel dysfunction is common in women with SUI, and also that women with low anal squeeze pressure prior to surgery for SUI are at greater risk for developing pelvic organ prolapse.
Anorectal Manometry as Treatment for Pelvic Floor Dysfunction
Pregnancy significantly increases the risk of fecal incontinence2 in women due to post partum changes in the pelvic floor. Oftentimes, women experience decreased pelvic floor strength, rendering them unable to adequately use their sphincter muscles for preventing defecation.
Anorectal manometry not only provides a method for diagnosing fecal incontinence and constipation, but it can also be used as a method to retrain the sphincter and anal muscles to function properly. Biofeedback utilizes ARM to provide visual or auditory feedback for patients while they learn to properly squeeze and release their anal muscles.
Numerous studies have shown the efficacy of this method in helping patients overcome fecal incontinence. For instance, in one study3, 26 patients with fecal incontinence underwent biofeedback training with ARM. Of these 26 patients, 10 had passive incontinence, 6 had urge incontinence, and 10 had both passive and urge incontinence. Out of the 22 patients that completed biofeedback training, 23% had excellent improvement, 41% showed good improvement, and 36% of patients showed no improvement. Patients with high degrees of anal sphincter asymmetry had worse results.
Ultimately, ARM is a complementary technique to many of the problems experienced by OBGYN clients, particularly due to the high number of women experiencing urinary incontinence, pelvic floor disorders, and fecal incontinence following pregnancy. For these reasons, OBGYN practitioners should offer anorectal manometry in their clinics.
If you are part of an ObGyn practice that is considering providing ARM, and want more information on how to offer it efficiently, click on the button below.
- Kjølhede P, Hallböök O, Rydén G, Sjödahl R. Anorectal manometry in women with urinary stress incontinence. Acta Obstet Gynecol Scand. 1997;76(3):266-70. Link
- Mckinnie V, Swift SE, Wang W, et al. The effect of pregnancy and mode of delivery on the prevalence of urinary and fecal incontinence. Am J Obstet Gynecol. 2005;193(2):512-7. Link
- Glia A, Gylin M, Akerlund JE, Lindfors U, Lindberg G. Biofeedback training in patients with fecal incontinence. Dis Colon Rectum. 1998;41(3):359-64. Link