Third-Trimester Low Back Pain: Naming the Dysfunction and Choosing a Technique
A 31-year-old G1P0 at 30 weeks' gestation presents with 3 weeks of worsening low back pain that radiates into the right buttock. Pain is worse with standing and prolonged sitting and is relieved by lying on her left side. Vitals: T 36.8 °C, HR 92, BP 118/72. She has no vaginal bleeding, leakage, or cramping, and reports normal fetal movement. Urinalysis at her OB visit last week was negative. On exam: lumbar flexion limited to 50% with pain at end-range extension; the seated flexion test is positive on the right; L4 is rotated right and sidebent left with a restrictive barrier in extension; paraspinal tissue texture change and tenderness extend from L3 to L5 on the right. Straight leg raise negative bilaterally; strength, reflexes, and sensation are normal.
1. State the segmental somatic dysfunction diagnosis using standard naming convention, and justify how the seated flexion test plus the rotational/sidebending findings localize it.
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Diagnosis: Somatic dysfunction of L4 (L3–L5 region), neutral mechanics - rotated right, sidebent left.
Reasoning chain:
- Seated flexion test - with the patient seated, arms crossed, and the examiner's thumbs on the inferior margins of the PSISs (or on lumbar transverse processes), forward flexion produces asymmetric cephalad movement. The side that moves first/furthest is the positive side, which localizes the side of the restriction. Here: right.
- Level - the segment is identified by palpation of motion restriction at each level on that side; the lowest most restricted segment is the key lesion. Here: L4.
- Mechanics - the lumbar spine follows Fryette type I (neutral) mechanics when the dysfunction is a group curve: sidebending and rotation occur to opposite sides. Right rotation with left sidebending is therefore internally consistent with a neutral group dysfunction and is not a type II (single-segment, same-side rotation and sidebending) pattern.
- Corroboration - tissue texture change, tenderness, and asymmetric springing at the named segment must accompany the positional findings before the diagnosis is written.
Why this matters: naming the asymmetry correctly determines the direction of the indirect (counterstrain) or direct (muscle energy) setup. An error in laterality produces a technique directed into the restrictive barrier rather than away from it.
2. Choose an OMT approach for this patient, specifying positioning and technique modifications for a third-trimester gravida, and state what you would avoid and why.
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Chosen techniques (with positioning):
- Muscle energy, lumbar rotation - patient in lateral recumbent (left side down, pillow under the head and between the knees) or supine with knees flexed over a bolster. Engage the barrier in flexion/extension, then use low-force, 3–5 second isometric contractions (operator force moderate, patient force ~20%) with a 2–3 second relaxation between repetitions. Muscle energy is the workhorse here: no thrust, patient-controlled dosing, and it is well tolerated late in pregnancy.
- Counterstrain for the tender paraspinal points, treating in lateral recumbent or seated rather than prone, 90 seconds of passive positional release.
- Soft tissue/myofascial release in lateral recumbent to address the thoracolumbar fascia, gluteal, and hip rotators; add pelvic girdle (sacroiliac, pubic symphysis) evaluation since pregnancy-related pelvic girdle pain commonly coexists and may be the dominant generator.
What to avoid:
- Prone positioning after roughly 20 weeks - aortocaval compression and inability to monitor fetal well-being; also uncomfortable.
- HVLA thrust in later pregnancy - generally avoided because of relaxin-mediated ligamentous laxity, altered balance/fall risk, and the inability to use standard setups; it is a relative, not absolute, contraindication, but the risk-benefit does not favor it here.
- Any direct pressure on the abdomen; keep the patient off her back for prolonged periods if she becomes symptomatic (supine hypotension).
Sequence: obtain OB concurrence that the pain is musculoskeletal, treat briefly (10–15 minutes), reassess the seated flexion test and lumbar range of motion immediately after, and reassess symptoms in 1–2 weeks. Document the technique, position, and response.
3. Before you attribute this pain to somatic dysfunction, what must be excluded, and how would you coordinate care and follow-up?
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Red flags to exclude in a third-trimester patient with new back pain:
- Preterm labor/abruption - contractions, cramping, vaginal bleeding, fluid leakage, decreased fetal movement (she is currently negative, but re-ask at each visit).
- Urinary tract infection/pyelonephritis - fever, dysuria, costovertebral angle tenderness. A negative UA last week does not cover an infection that began since; recheck if symptoms are present.
- Nephrolithiasis - colicky flank pain, hematuria.
- Preeclampsia - check BP and ask about headache, visual change, and right upper quadrant pain; back pain alone is not typical, but the assessment is cheap.
- Venous thromboembolism - unilateral leg swelling, calf tenderness (pregnancy is a hypercoagulable state).
- Cauda equina/conus medullaris - saddle anesthesia, new bowel or bladder dysfunction, bilateral leg weakness.
- Infection or malignancy of the spine - fever, night pain, unintentional weight loss, prior cancer, immunosuppression, pain unrelieved by rest.
Coordination and follow-up:
- Send a note to the OB team documenting the musculoskeletal exam and that OMT was performed - in pregnancy, OMT is an adjunct, not a substitute for obstetric evaluation.
- Give a clear return-precaution list (bleeding, contractions, leakage, decreased fetal movement, fever, leg swelling).
- Reassess in 1–2 weeks; if pain is not improving or is progressive, or if any red flag develops, escalate rather than adding more OMT sessions.
- Document shared decision-making: the patient understands the expected benefit (symptom relief) and that the natural history of pregnancy-related back pain is improvement after delivery.