A 36-year-old woman, gravida 2 para 1, at 32 weeks gestation comes to the office with dull, low back pain radiating bilaterally to the buttocks and posterior thighs. The pain is minimal in the morning but increases with activity and at the end of the day. She also has ankle edema and numbness in her feet at the end of the day. The patient has urinary frequency and nocturia but no hematuria or dysuria. She had no back pain in her first pregnancy. During that delivery, the patient received epidural anesthesia and had a post–lumbar puncture headache after removal that was treated with an epidural blood patch. Temperature is 36.7 C (98.1 F), blood pressure is 120/80 mm Hg, and pulse is 90/min. She has gained 20 kg (44.1 lb) during this pregnancy. On physical examination, the patient ambulates with a wide, waddling gait. Walking forward or backward causes no change in pain level. There is no spinal or paravertebral tenderness. Deep tendon reflexes are 2+. The abdomen is soft, and the cervix is long, closed, and posterior. Which of the following is the most appropriate next step in management of this patient?
Low back pain during pregnancy | |
Etiology |
|
Risk factors |
|
Imaging |
|
Management |
|
Low back pain and waddling gait are common in pregnancy, especially in the third trimester because uterine enlargement causes exaggerated lordosis and postural changes. Other contributing factors include weakened abdominal muscles and increased joint/ligament laxity. Risk factors include multiparity and excessive weight gain, as in this patient. Prior neuraxial anesthesia does not increase the risk for long-term back pain.
Back pain during pregnancy typically manifests as mechanical back pain (eg, position-dependent, achy, worsened with activity, relieved with rest). In contrast, concerning nonmechanical causes of back pain (eg, preterm labor, pyelonephritis, spinal malignancy) may present with fever, neurologic deficits (eg, bowel or bladder incontinence), and constant, nonpositional, nocturnal back pain.
This patient has no associated neurologic deficits. Her back pain is bilateral without radiation below the knee, making lumbosacral radiculopathy (sciatica) unlikely. The numbness in her feet, which is present only at the end of the day, is likely related to physiologic ankle edema. Patients with no concerning findings, such as this one, should receive reassurance that the back pain is normal and will resolve postpartum. Conservative management, such as behavioral modifications (eg, wearing supportive shoes, using a firm mattress) and exercise, is recommended. Heating pads and massage are also beneficial.
(Choice A) Epidural corticosteroid injections can provide short-term relief for chronic radicular pain from lumbar disc herniation (ie, unilateral pain radiating below the knee along the sciatic nerve). However, this patient's pain is bilateral and does not radiate below the knee, making this diagnosis unlikely. Epidural injections are not recommended for mechanical back pain.
(Choice B) MRI is the preferred imaging modality for pregnant women with back pain but is usually needed only when there are associated neurologic deficits, features of infection (eg, fever, focal spinal tenderness), or malignancy (eg, unexpected weight loss). Minor pregnancy-related symptoms (eg, urinary frequency, edema) do not require imaging.
(Choice D) Strict bed rest is rarely recommended in pregnancy due to the increased risk for thromboembolism, bone loss, and physical deconditioning, which can exacerbate back pain.
(Choice E) Nonsteroidal anti-inflammatory drugs (eg, ibuprofen, naproxen) are avoided in the first and third trimesters due to risks for renal teratogenicity and premature closure of the ductus arteriosus.
Educational objective:
Low back pain is common in the third trimester due to postural changes, weakened abdominal muscles, and joint/ligament laxity. Patients with no concerning findings or neurologic deficits should receive reassurance and conservative management (eg, exercise, heating pads, massage).