Research Review By Dr. Ceara Higgins©


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Date Posted:

September 2016

Study Title:

Effect of Spinal Manipulation on Pelvic Floor Functional Changes in Pregnant and Nonpregnant Women: A Preliminary Study


Haavik H, Murphy B & Kruger J

Author's Affiliations:

New Zealand College of Chiropractic, Auckland, New Zealand; University of Ontario Institute of Technology, Oshawa, Ontario, Canada; The University of Auckland in New Zealand, Auckland, New Zealand.

Publication Information:

Journal of Manipulative and Physiological Therapeutics 2016; 39: 339-347.

Background Information:

During exercise and increases in intra-abdominal pressure, pelvic floor muscles (PFMs) coactivate with the abdominal muscles, especially the transverse abdominus (1). After difficult vaginal deliveries, especially ones where intervention is required, PFM dysfunction is common and can manifest as stress urinary incontinence, pelvic organ prolapse, and/or fecal incontinence (2). Not surprisingly, the social and economic cost of PFM dysfunction can be significant, not to mention the personal burden (3).

Previous studies have shown significant improvements in the feed-forward activation of the transverse abdominus (TA) after sacroiliac manipulation (4) and abdominal oblique muscle activation after lumbar spine mobilization (5). In theory, if PFMs and TA coactivate and lumbopelvic manipulation can alter abdominal muscle actions, then lumbopelvic manipulation may also be able to affect PFM activity and therefore may be beneficial during the second stage of labour if they allow the PFMs to stretch (make sense?).

3- and 4-dimensional (3D/4D) transperineal ultrasonography has been found to be a reliable and effective method to assess PFM function (6) and is non-invasive, quick, easily accessible, inexpensive, and has been deemed safe in pregnancy. The authors of this preliminary study used 3D/4D ultrasonography to assess alterations in pelvic floor function in pregnant women due to spinal manipulation.

Pertinent Results:

Spinal manipulation in second trimester pregnant women appeared to relax the PFMs at rest. This was demonstrated as an increase in levator hiatus area when measured with translabial 3D ultrasonography. No changes were seen in the control group, which indicates that the increase may specifically be a result of the manipulation. Pregnant women showed average increases of 2.3cm2 in levator hiatal area at rest.

Clinical Application & Conclusions:

This preliminary study (with only 11 subjects in the experimental group) showed that manipulation of the lumbar spine or pelvis can lead to relaxation of the PFMs in pregnant women at rest. This relaxation is likely to be of benefit in vaginal deliveries, especially in individuals who are not progressing through the second stage of labour. Further research in larger patient populations is needed to validate and expand upon these results.

Study Methods:

Eleven pregnant women were recruited via notice boards at obstetric caregivers, pregnancy keep-fit classes, and word of mouth. Women were required to be in the second trimester of their first pregnancy, with no history of recurrent miscarriage, and no evidence of a high-risk pregnancy. Fifteen nulliparous female students from the New Zealand College of Chiropractic were recruited to act as a control group. Women in both groups were between 18 and 35 years of age and were excluded if they had any symptoms of stress urinary incontinence, pelvic organ prolapse, or any known contraindications to receiving chiropractic adjustments.

Participants filled out an eligibility questionnaire and those who appeared eligible were assessed more fully for symptoms of possible pelvic floor dysfunction, pelvic surgery, or family history of pelvic floor dysfunction. They were next assessed by a registered chiropractor and a thorough health history was collected. The chiropractor assessed participants for spinal dysfunction through tenderness to palpation of the relevant joints, manual palpation for restrictions in intersegmental range of motion, palpation for asymmetric intervertebral muscle tension, and any abnormal or blocked joint play and joint end-feel. Areas of dysfunction were manipulated as clinically indicated through high-velocity, low-amplitude thrusts. The control intervention included passive and active movements of the participant’s head, spine, and body, moving them into the manipulation setup position while carefully avoiding applying any pressure on any individual spinal segments. This was carried out by the same treating chiropractor. This was not intended to be a sham manipulation, but rather a physiological control for potential changes that may occur due to cutaneous, muscular, or vestibular input related to positioning a patient prior to delivering a manipulation.

Pelvic floor ultrasonography was acquired according to previously published methodology (7) and was performed before and after either the spinal manipulation or the control session, by an experienced PFM ultrasonographic operator. In the non-pregnant women, the manipulation session and control session were performed on different days (in randomized order), while the pregnant women received the initial scan, control session, and manipulation session sequentially on the same day in order to minimize their time involvement. This also minimized the effect of increased gestation. The probe was oriented in the midsaggital plane on the perineum. Participants were asked to void before imaging. Volume data sets were collected at rest, on maximum PFM contraction (PFMC), and during maximum Valsalva with the most effective PFMC and Valsalva used for measurement purposes. Hiatal areas and anterior-posterior and lateral diameters were recorded under all three conditions.

Study Strengths / Weaknesses:

  • This area of research has not been well explored in the past and the potential for patient benefit from this type of intervention is high.
  • The use of the control group to account for possible effects from preload is helpful in determining if the effect noted was a result of the manipulation.
  • The was a preliminary study and as such, utilized a small sample size.
  • The time frame for the interventions was different in the non-pregnant cohort than in the pregnant cohort.
  • Not all of the pregnant women were familiar with chiropractic, while all of the nonpregnant women were familiar with chiropractic. It is therefore possible that the effect seen in the pregnant cohort may be partly due to it being their first exposure to chiropractic.

Additional References:

  1. Sapsford RR, Hodges PW. Contraction of the pelvic floor muscles during abdominal manoeuvres. Arch Phys Med Rehabil 2001; 82(8): 1081-1088.
  2. Connolly A, Thorp J. Childbirth-related perineal trauma: clinical significance and prevention. Clin Obstet Gynecol 1999; 42(2): 820-835.
  3. Wilson L Brown JS, Shin GP, et al. Annual direct cost of urinary incontinence. Obstet Gynecol 2001; 98(3): 398-406
  4. Marshall P, Murphy B. The effect of sacroiliac joint manipulation on feed-forward activation times of the deep abdominal musculature. J Manipulative Physiol Ther 2006; 29(3): 196-202.
  5. Ferreira ML, Ferreira PH, Hodges PW. Changes in postural activity of the trunk muscles following spinal manipulative therapy. Man Ther 2007; 12(3): 240-248.
  6. van Veelen G, Schweitzer K, van der Vaart C. Reliability of pelvic floor measurements on three- and four-dimensional ultrasound during and after first pregnancy: implications for training. Ultrasound Obstet Gynecol 2013; 42(5): 590-595.
  7. Dietz H, Shek C, Clark B. Biometry of the pubovisceral muscle and levator hiatus by 3D pelvic floor ultrasound. Ultrasound Obstet Gynecol 2005; 25: 580-585.