Gynecologic disorders may manifest themselves by back pain, and their diagnosis may prove difficult. Thorough abdominal palpation, as well as vaginal and rectal examination by an experienced physician, supplemented by ultrasonography and CT scanning or MRI, usually discloses the source of pain. The uterosacral ligaments are the most important pelvic source of chronic back pain. Endometriosis or carcinoma of the uterus (body or cervix) may invade these structures, causing pain localized to the sacrum either centrally or more to one side. In endometriosis, the pain begins premenstrually and often merges with menstrual pain, which also may be felt in the sacral region. Rarely, cyclic engorgement of ectopic endometrial tissue may give rise to sciatica and other radicular pain. Changes in posture may also evoke pain here when a fibroma of the uterus pulls on the uterosacral ligaments. Low back pain with radiation into one or both thighs is a common phenomenon during the last weeks of pregnancy.
Pain from neoplastic infiltration of pelvic nerve plexuses may be projected to the low back and is continuous, becoming progressively more severe; it tends to be more intense at night and may have a burning quality. The primary lesion can be inconspicuous and may be inevident on pelvic examination.
Traumatic Disorders of the Low Back
In severe acute lumbar injuries from direct impact the examiner must be careful to avoid further damage and movements should be kept to a minimum until an approximate diagnosis has been made. If the patient complains of pain in the back immediately after impact and cannot move the legs, the spine may have been fractured and the cord or cauda equina compressed or crushed. The neck should not be manipulated, and the patient should not be allowed to sit up. (See Chap. 42 for further discussion of spinal cord injury.) Lesser degrees of injury, such as sprains and strains, are ubiquitous and can be handled with less caution because they do not involve compression of neural structures.
Acute sprains and strains The terms lumbosacral strain, sprain, and derangement are used loosely and it is difficult to differentiate them. Furthermore, what was formerly referred to as “sacroiliac strain” or “sprain” is now known to be caused in some instances, by disc disease. The term acute low back strain may be preferable for minor, self-limiting injuries that are usually associated with lifting heavy loads when the back is in a mechanically disadvantaged position, or there may have been a fall, prolonged uncomfortable postures such as air travel or car rides, or sudden unexpected motion, as may occur in an auto accident.
Nonetheless, the discomfort of acute low back strain can be severe, and the patient may assume unusual postures related to spasm of the lower lumbar and sacrospinalis muscles. The pain is usually confined to the lower part of the back, in the midline, across the posterior waist, or just to one side of the spine. The diagnosis of lumbosacral strain is dependent on the biomechanics of the injury or activity that precipitated the pain. The injured structures are identified by the localized tenderness, augmentation of pain by postural changes—for example, bending forward, twisting, or standing up from a sitting position, and by the absence of signs of radicular involvement. In more than 80 percent of cases of acute low back strain of this type, the pain resolves in a matter of several days or a week, even with no specific treatment.
Sacroiliac joint and ligamentous strain is the most likely diagnosis when there is tenderness over the sacroiliac joint and pain radiating to the buttock and posterior thigh, but this needs to be distinguished from the sciatica of a ruptured intervertebral disc (see further on). Strain is characteristically worsened by abduction of the thigh against resistance and may produce pain that is also felt in the symphysis pubis or groin. It, too, responds within days or a week or two to conservative management.