What are the causes and treatment options for left shoulder pain during pregnancy?

Left Shoulder Pain in Pregnancy: Causes and Treatment Options

Left shoulder pain during pregnancy can be caused by musculoskeletal issues, but may also be a concerning sign of serious conditions like ectopic pregnancy or cardiovascular problems, requiring prompt evaluation and appropriate management based on the underlying cause.

Common Causes of Left Shoulder Pain in Pregnancy

Musculoskeletal Causes

• Musculoskeletal pain is extremely common during pregnancy, with prevalence peaking in months 6 and 7 of gestation 1
• Pregnancy-related hormonal changes cause joint laxity and reduced ligament rigidity, weakening joint stability and increasing demand on stabilizing muscles 1
• Biomechanical changes from increased abdominal mass and shifts in center of gravity create additional load on the musculoskeletal system, including the shoulder girdle 1, 2
• Postural adaptations to accommodate the growing fetus place stress on the spine and supporting structures, which can refer pain to the shoulder region 1, 3

Serious Medical Conditions (Requiring Urgent Attention)

• Left shoulder pain can be a referred pain symptom from diaphragmatic irritation due to intraperitoneal bleeding from a ruptured ectopic pregnancy 4, 5
• Cardiovascular issues during pregnancy, including acute coronary syndromes or aortic dissection, may present with left shoulder pain 6
• Pulmonary embolism, which occurs more frequently during pregnancy, can sometimes present with referred shoulder pain 6

Post-Procedural Causes

• Shoulder pain after cesarean section is reported in up to 39.45% of women, more commonly with general anesthesia than spinal anesthesia 7
• Post-surgical shoulder pain is typically due to diaphragmatic irritation from residual carbon dioxide used during laparoscopic procedures or air trapped under the diaphragm 7

Diagnostic Approach

Initial Assessment

• Evaluate for red flags that suggest serious pathology:
  • Severe pain with hemodynamic instability (tachycardia, hypotension) 4
  • Associated symptoms like vaginal bleeding, abdominal pain, or syncope (suggesting possible ectopic pregnancy) 4, 5
  • Chest pain, shortness of breath, or palpitations (suggesting possible cardiovascular or pulmonary causes) 6

Physical Examination

• Assessment of the painful shoulder should include evaluation of:
  • Range of motion, strength, and tone 6
  • Changes in length of soft tissues and alignment of joints in the shoulder girdle 6
  • Levels of pain and orthopedic changes in the shoulder 6

Imaging Considerations

• Ultrasound is the primary imaging modality for evaluating abdominal and pelvic causes of referred shoulder pain during pregnancy 6, 4
• MRI is recommended as the next step following ultrasound when additional imaging is needed for musculoskeletal causes, to avoid radiation exposure 6, 4
• CT should be avoided when possible due to radiation concerns, but should not be withheld in life-threatening situations 6, 4

Treatment Approaches

For Musculoskeletal Causes

• Non-pharmacological approaches should be first-line treatment:

  • Gentle stretching and mobilization techniques, focusing on increasing external rotation and abduction 6, 2
  • Active range of motion exercises should be increased gradually in conjunction with restoring alignment and strengthening weak muscles in the shoulder girdle 6
  • Rest and activity modification, especially avoiding heavy lifting (10-20 kg or 22-44 lb) more than 20 times per week 1, 2

• Pharmacological management (if needed):

  • If there are no contraindications, acetaminophen can be used for pain relief as a first-line medication 6, 2
  • NSAIDs like ibuprofen should be used with caution and only for short periods, particularly avoiding use in the third trimester 6, 2

For Serious Medical Conditions

• Ectopic pregnancy with intraperitoneal bleeding requires immediate surgical intervention 4, 5
• Cardiovascular conditions like acute coronary syndrome during pregnancy require specialized care:
  • Coronary angiography with the possibility of coronary intervention (PCI) is preferred to thrombolysis 6
  • β-Blockers and low-dose acetylsalicylic acid are considered relatively safe during pregnancy 6
  • ACE inhibitors, angiotensin receptor blockers (ARBs), and renin inhibitors are contraindicated during pregnancy 6

Prevention and Long-term Management

• For most women, pregnancy-related musculoskeletal pain resolves spontaneously after delivery 1
• Women at highest risk for persistent postpartum pain include those who had pain prior to pregnancy, experienced early onset of symptoms during pregnancy, or had higher pain severity during pregnancy 1
• Prevention of Complex Regional Pain Syndrome (CRPS) through active, active-assisted, or passive range of motion exercises is recommended 6

Common Pitfalls in Management

• Underreporting: Women often don't report musculoskeletal pain to their prenatal providers, leading to insufficient clinical attention 1
• Failing to recognize referred shoulder pain as a potential sign of serious conditions like ectopic pregnancy or cardiovascular issues 4, 5
• Inadequate activity modification: Failing to adjust physical activities, especially heavy lifting, can worsen symptoms 1
• Ignoring persistent symptoms: Persistent pain requires evaluation as it may indicate more serious underlying conditions 1