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Back Pain and Pregnancy: Active Management Strategies

Julie Colliton, MD

THE PHYSICIAN AND SPORTSMEDICINE - VOL 24 - NO. 7 - JULY 96


In Brief: For about half of all pregnant women, low-back pain is inevitable. Physicians who can specify what type of back pain the patient has—lumbar, sacroiliac, or nocturnal—can institute targeted treatment that addresses the relevant pathophysiology. Acetaminophen and certain modalities such as icing the area are the basis of acute treatment in conjunction with ergonomic adaptation and a good low-back exercise program. This will help decrease stress on the low back, making back pain less likely. Before a woman becomes pregnant, encouraging her to become fit and resolving existing back problems is the key to back pain prevention.

If the discomfort of back pain during pregnancy can be severe enough to warrant sick days and disrupt sleep, it's easy to deduce that it could be an obstacle to activity for women who want to reap the health benefits of exercise during pregnancy. In the past, women were told that biomechanical low-back pain was simply part of pregnancy. Now, though, it is known that the causes of low-back pain during pregnancy are specific and that effective treatment should be geared toward the precise pathology.

Formal study of the incidence of low-back pain in pregnancy has been very limited. The overall prevalence of back pain during the 9-month period is thought to be approximately 50% (1,2). Pain can begin before week 12 and continue up to 6 months postpartum.

Various studies (1,3-6) have examined the risk factors that contribute to the development of low-back pain during pregnancy. Prepregnancy back pain and multiparity seem to be risk factors, whereas age, height, weight, race, fetal weight, and socioeconomic status do not seem to correlate.

Low-back pain during pregnancy can be classified into three types:

  • Lumbar pain can occur with or without radiation to the legs. True sciatica is rare and thought to account for a small percentage of low-back pain in pregnancy (7,8).
  • Sacroiliac pain is felt distal and lateral to the lumbar spine near the posterior superior iliac spine, and may radiate to the posterolateral thigh, usually to the level of the knee and rarely to the calf. It is four times more common than lumbar pain (9). Symptoms of sacroiliac joint pain typically continue several months after delivery. It is thought that 20% to 30% of pregnant women experience both lumbar and sacroiliac pain (10).
  • Nocturnal pain occurs in the low back only at night while recumbent.

Why Does Her Back Hurt?

Understanding the normal musculoskeletal changes that occur during pregnancy is useful for targeting and treating the sites of a patient's back pain.

Lumbar pain. Lumbar pain during pregnancy can stem from multiple sites, most commonly the facet joints, paraspinal muscles, supporting ligaments, or discogenic sources.

Posture changes that occur during pregnancy help the woman maintain balance in the upright position as the fetus grows. The increasing weight is distributed primarily in the abdominal girth. After 12 weeks of pregnancy the uterus expands out of the pelvis and moves superiorly, anteriorly, and laterally. The abdominal muscles become less effective at maintaining neutral posture (shoulders back, avoiding hyperlordosis) because the growing uterus stretches the muscles, reducing their tone. Initially, however, studies have shown that lumbar lordosis remains the same or increases only slightly (11). The center of gravity as a whole, though, shifts more posteriorly and inferiorly as the spine moves posterior to the center of gravity.

As pregnancy progresses, the hormone relaxin, which allows pelvic expansion to accommodate the enlarging uterus, increases tenfold, reaching its peak at the 14th week (12,13). Joint laxity is more pronounced in multiparous women than it is during the first pregnancy. In the lumbar spine, joint laxity is most notable in the anterior and posterior longitudinal ligaments, both of which are pain-sensitive structures. As these static supports in the lumbar spine become more lax, they can't as effectively withstand shear forces, and discogenic symptoms and/or pain from the facet joints may increase.

As the abdominal muscles stretch to accommodate the growing fetus, their ability to help stabilize the pelvis decreases. The burden shifts to the paraspinal muscles, which become strained at a time when they may be shortened from the increased lordosis of the lumbar spine.

Sacroiliac pain. In the pelvis, joint laxity is most prominent in the symphysis pubis and the sacroiliac joints. The symphysis pubis widens throughout pregnancy from its normal width of .5 mm to a maximum of approximately 12 mm. With widening comes the possibility of vertical displacement of the pubis and rotatory stress on the sacroiliac joints.

In the nonpregnant state, the sacroiliac joints are extremely stable with tight anterior and posterior ligament support and a sigmoid articular surface that limits movement. During pregnancy, however, movement in the sacroiliac joints can increase dramatically, causing discomfort when the pain-sensitive ligamentous structures are stretched.

Nocturnal pain. Some women have night back pain exclusively, others have both night pain and lumbar or sacroiliac pain. There are many theories about why night pain develops. One theory is that muscle fatigue accumulates throughout the day and culminates in back pain at night. Another is that daylong biomechanical stress from sacroiliac dysfunction or mechanical low-back pain from altered posture produces symptoms in the evening. Circulatory changes during pregnancy may also contribute to low-back pain at night. The enlarging fetus compresses the inferior vena cava when the woman is supine, which may divert blood flow to the ascending lumbar veins, the vertebral venous plexus, the paraspinal veins, and the azygous system (14). The intravascular volume increase when the pregnant woman is supine may contribute to engorgement of the collateral neurovascular structures, producing low-back pain at night (15,16).

Examination Strategies

History. The patient history is perhaps the most useful tool in differentiating the cause of pregnancy-related back pain. Patients should be asked to describe the location, nature, and duration of their pain. The physician can ask patients to draw the location and radiation of their pain on an anatomic diagram for the medical record.

Women with lumbar back pain have pain while weight-bearing and seated for prolonged periods. The pain diagram will show centralized low lumbar pain, with or without lower extremity radiation.

Women who have sacroiliac pain will describe pain in the posterior pelvis and deep in the gluteal area. Those who have sacroiliac pain as their primary complaint generally have low-back pain longer throughout the pregnancy than those who have only lumbar low-back pain. The pain is exacerbated by any prolonged posture, especially during weight-bearing. The patient's pain diagram will show well-defined markings of stabbing pain in the buttocks distal and lateral to L5-S1. Patients may or may not describe radiation to the posterolateral lower extremity as far as the popliteal fossa; typically the pain will not extend to the foot. The patient also will describe pain that occurs while turning in bed at night.

Women who have nocturnal pain often describe a low-back cramp that is similar to the low-back ache of menstruation. It may be severe enough to awaken them from sleep. Unlike patients who have sacroiliac or lumbar pain, women with nocturnal pain will not describe pain from turning in bed.

Physical exam. On physical exam for lumbar, sacroiliac, or night back pain there will be no evidence of neurologic deficit or hip pathology. The examiner screens for muscle weakness, sensory impairment, and reflex changes that might suggest radiculopathy. In patients who have lumbar low-back pain, the physical exam will be most consistent with discogenic and/or facet pain. Discogenic pain is typically most pronounced on flexion of the back, as when touching the toes from a standing position. Returning to standing is less painful than going into flexion. If there is a component of instability in the lumbar spine, the patient may have to perform portions of the Gowers' maneuver (the patient rolls to the prone position, kneels, and rises to standing by pushing the hands against the shins, knees, and thighs) to get from sitting to standing or standing flexion to upright. In facet pain, the pain is most pronounced when the spine is extended and will be localized to the level of the irritated facet. Extension and rotation to the symptomatic side increase the pain even more.

[FIGURE 1]If the source is sacroiliac, pain will likely occur with back extension and rotation to the symptomatic side. The posterior pelvic pain provocation test has been found most likely to correlate with sacroiliac pain of pregnancy (figure 1). The test is 81% sensitive and 80% specific for sacroiliac pain during pregnancy (17). Other tests that can localize pain to the sacroiliac joint include the ventral gapping test, which is positive when manual separation of the sacroiliac joint reproduces the pain, and the dorsal gapping test, which is positive when pelvis compression reproduces the pain. The tests are performed with the patient supine.

The sacroiliac joint fixation test evaluates the mobility of the sacroiliac joint; a greater-than-normal degree of motion correlates with pain. The examiner observes the patient's posterior superior iliac spine during forward flexion; the test is positive if the posterior superior iliac spine on the painful side is level to or lower than the opposite side and the position is reversed or elevated when she goes into flexion while standing.

Patrick's test is performed to evaluate for sacroiliac pain. While supine, the patient flexes one hip and knee, and places the external malleolus of that leg over the patella of the other knee. The test is positive if depression of the knee reproduces the patient's pain. The test is also called the fabere sign, an acronym that incorporates the initial letters of the movements required to perform the test: flexion, abduction, external rotation, and extension. Derbolowski's test screens for asymmetric movement of the two sacroiliac joints. The examiner observes the positions of the medial malleoli while the woman is sitting and supine. The test is positive if the positions of the medial malleoli change in relation to one other as the patient moves from sitting to supine.

Radiographs are not part of the diagnostic work-up for pregnant women who have back pain. Typically, the physical exam is enough to make the diagnosis. Magnetic resonance imaging (MRI) can be performed if the examiner diagnoses a radioculopathy and is considering surgery or epidural steroid treatment.

Treatment Options

Initial treatment for pregnant patients with low-back, sacroiliac, or night pain consists of modalities such as heat and ice. Acetaminophen may help relieve the patient's pain. Nonsteroidal anti-inflammatory drugs are contraindicated during pregnancy. When pain is extremely severe, certain narcotics may be appropriate. Massage therapy may provide short-term pain relief. Pregnant women with back pain should avoid whirlpool treatment as well as joint manipulation procedures; low-impulse, high-exercise-velocity procedures are contraindicated during pregnancy. Patients who do not respond to conservative treatment may need regular physical therapy visits to achieve a more structured, aggressive back stabilization program.

Proper posture can prevent unnecessary mechanical stress on the low back. Pregnant women should understand that weight gain and hormonal changes place more stress on their low back and pelvis at a time when ligaments and joints are becoming more lax. Physicians can teach women the neutral spine posture that avoids excessive lumbar lordosis and excessive reversal of lumbar lordosis. Women can be instructed to perform all activities in the neutral spine posture; observing the patient in a physical therapy department simulating her usual daily activities can ensure that she knows how to maintain a neutral spine. Patients should be aware of a common fatigue reaction to prolonged standing—moving the shoulders more posteriorly—that increases lumbar lordosis. Pregnant women should avoid wearing high-heeled shoes that accentuate lumbar lordosis and increase shearing stress on the lower back and sacrum.

Ergonomic enhancements may reduce back pain during pregnancy. When patients stand for long periods, placing one foot on a foot stool relaxes the iliopsoas muscles and tilts the pelvis forward, decreasing the strain on the lumbar spine and paraspinal musculature. For those who sit for prolonged periods, elevating one foot on a low stool or foot rest relaxes the iliopsoas and reduces lumbar lordosis, thus reducing traction on the pelvis. For patients who have sacroiliac pain with objective evidence of biomechanical dysfunction, a nonelastic trochanteric belt may decrease pain when they are walking for prolonged periods. Uterus supports in bed are helpful for night pain; while in a side-lying position, the woman places pillows beneath her abdomen and between her legs. The benefit of lumbar supports in chairs is subjective, and they may help some women.

Exercise programs are prescribed to improve the strength and condition of supporting structures. The exercises help the patient maintain a neutral spine posture, promote biomechanic efficiency, and minimize stress on the back. The exercises may prevent and relieve lumbar and sacroiliac pain, but not night pain. Exercises for patients who have low-back pain should be easy to follow (see "Pregnant With Back Pain? Suggested Comfort Tactics"). Initially, patients should be coached by a skilled therapist who is familiar with pregnancy-related back pain. Exercises that are done lying flat on the back should be modified or omitted after the third month.

Prepregnancy Counseling

The physician should ask women who are contemplating pregnancy about their history of low-back problems. If the history is positive, the physician should ascertain whether the symptoms have been evaluated and treated. Women with a history of low-back pain should be informed about the increased risk of symptom recurrence during pregnancy. Physically fit women who get 45 minutes or more of physical activity a week are less likely to develop lumbar pain during pregnancy (9), however, prepregnancy fitness does not seem to decrease the risk of developing sacroiliac pain (5).

A Good Comfort Zone

Patients should be aware that exercise and posture correction will minimize but not completely prevent lumbar or sacroiliac pain during pregnancy. Sometimes simple reassurance that symptoms are temporary is enough to alleviate a pregnant woman's concern about back pain. However, it takes a targeted treatment plan to address chronic pain that interferes with activity and/or sleep—two key components of a healthy pregnancy.

References

  1. Mantle MJ, Greenwood RM, Currey HL: Backache in pregnancy. Rheumatol Rehabil 1977;16(2):95-101
  2. Hammar M, Berg G, Lilliesköld U, et al: Back pain during pregnancy [in Swedish]. Swed Med J 1986; 83(21):1960-1961
  3. Berg G, Hammar M, Möller-Nielsen J, et al: Low back pain during pregnancy. Obstet Gynecol 1988; 71(1):71-75
  4. Fast A, Shapiro D, Ducommun EJ, et al: Low-back pain in pregnancy. Spine 1987;12(4):368-371
  5. Fast A, Weiss L, Ducommun EJ, et al: Low-back pain in pregnancy: abdominal muscles, sit-up performance and back pain. Spine 1990;15(1):28-30
  6. Svensson HO, Andersson GB, Hagstad A, et al: The relationship of low-back pain to pregnancy and gynecologic factors. Spine 1990;15(5):371-375
  7. Östgaard HC, Andersson GB, Karlsson K: Prevalence of back pain in pregnancy. Spine 1991;16(5):549-552
  8. Hainline B: Low-back pain in pregnancy. Adv Neurol 1994;64:65-76
  9. Östgaard HC, Zetherström G, Roos-Hansson E, et al: Reduction of back and posterior pelvic pain in pregnancy. Spine 1994;19(8):894-900
  10. Endresen EH: Pelvic pain and low back pain in pregnant women: an epidemiological study. Scand J Rheumatol 1995;24(3):135-141
  11. Hummel P: Changes in Posture During Pregnancy. Philadelphia, WB Saunders, 1987
  12. Petersen LK, Vogel I, Agger AO, et al: Variations in serum relaxin (hRLX-2) concentrations during human pregnancy. Acta Obstet Gynecol Scand 1995;74 (4):251-256
  13. Calguneri M, Bird HA, Wright V: Changes in joint laxity during pregnancy. Ann Rheum Dis 1982;41(2):126-128
  14. McCarthy SM, Stark DD, Filly RA, et al: Obstetrical magnetic resonance imaging: maternal anatomy. Radiology 1985;154(2):421-425
  15. Fast A, Weiss L, Parikh S, et al: Night backache in pregnancy: hypothetical pathophysiological mechanisms. Am J Phys Med Rehabil 1989;68(5):227-229
  16. Wyke B: The neurology of low back pain, in Jaydon MIV (ed): The Lumbar Spine and Back Pain, ed 3. New York City, Churchill Livingstone, 1987, pp 56-99
  17. Roos-Hansson E, Zetherström G: Reliability of provocation test in posterior pelvic pain during pregnancy. Sjukgymnasten, Vetenskapligt 1991;2:23-24

Dr Colliton is a physiatrist with Denver Spine & Rehabilitation, PC in Denver. She is a member of the Women's Sportsmedicine Committee of the American College of Sports Medicine and a team physician for the US Disabled Ski Team. Address correspondence to Julie Colliton, MD, Denver Spine and Rehabilitation, PC, 1000 S Colorado Blvd, Denver, CO 80222; e-mail to [email protected]


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