What are the recommended evaluation and management steps for a pregnant woman with a history of previous cesarean section (C-section) presenting with abdominal pain and back pain?

Evaluation and Management of Abdominal and Back Pain in Pregnancy After Previous Cesarean Section

A pregnant woman with prior cesarean section presenting with abdominal and back pain requires urgent evaluation to exclude uterine rupture, which has a doubled risk (0.7%) when acute persistent abdominal pain localizes over the previous cesarean scar. 1

Immediate Risk Stratification

Critical Red Flags Requiring Emergency Assessment

• Acute persistent abdominal pain (APAP) over the previous cesarean scar is associated with a 0.7% incidence of uterine rupture—double the baseline risk of 0.35% in women with prior cesarean 1
• Uterine rupture occurs in 0.22% of women with previous cesarean at baseline, increasing to 0.35% when labor occurs 2
• Severe abdominal pain with nausea/vomiting may indicate internal herniation if the patient has history of bariatric surgery, with maternal mortality of 9% and fetal mortality of 13.6% when treatment is delayed beyond 48 hours 2
• All maternal and perinatal deaths from internal herniation after gastric bypass occurred in women treated later than 48 hours after symptom onset 2

Pain Characteristics That Guide Diagnosis

• Location matters: Pain specifically over the previous cesarean scar carries doubled rupture risk compared to generalized abdominal pain 1
• Timing is critical: 20% of uterine ruptures occur in preterm weeks, and 40% of women with APAP over previous cesarean scar deliver preterm 1
• Associated symptoms: Fever, tachycardia, or signs of peritonitis suggest infection or perforation requiring immediate surgical evaluation 3

Algorithmic Diagnostic Approach

Step 1: Immediate Clinical Assessment

• Vital signs assessment: Check for fever (infection), tachycardia (hemorrhage/infection), hypotension (rupture/hemorrhage) 3
• Abdominal examination: Assess for peritoneal signs, uterine tenderness, location of maximal pain relative to cesarean scar 2, 1
• Obstetric evaluation: Fetal heart rate monitoring, assessment for contractions, vaginal bleeding, ruptured membranes 2
• Surgical history: Document number of previous cesareans (risk increases with each: 0.22% baseline to 0.35% with labor after one cesarean) 2

Step 2: Imaging Protocol

Transabdominal ultrasound is the preferred initial imaging modality 2

• Evaluate for uterine rupture: Look for myometrial discontinuity; lower uterine segment thickness <2.5 mm predicts uterine dehiscence 2
• Assess for placental abruption: Use color/power Doppler to identify areas contiguous with placenta showing no blood flow (suggests acute clot) 2
• Rule out placenta previa/accreta: Risk increases from 3.3/10,000 at baseline to 12.9/10,000 after one cesarean for accreta 4
• Transvaginal ultrasound if transabdominal views are inadequate, particularly for lower uterine segment and cervical assessment 2

Step 3: Risk-Stratified Management

HIGH RISK (Immediate Surgical Consultation Required)

• Acute persistent pain localized over cesarean scar 1
• Signs of peritonitis or hemodynamic instability 3, 5
• Ultrasound evidence of myometrial disruption or lower uterine segment <2.5 mm 2
• History of multiple cesareans (≥3 increases accreta risk to 78.3/10,000) 2

Action: Immediate obstetric and surgical consultation; prepare for emergency cesarean delivery with capability for hysterectomy 2

MODERATE RISK (Close Monitoring Required)

• Generalized abdominal pain without scar localization 1
• Back pain with uterine contractions (may indicate early labor or abruption) 2
• History of bariatric surgery with upper abdominal pain (32.8% have internal herniation) 2

Action: Serial ultrasound monitoring every 2-4 weeks in third trimester to assess scar integrity 4; hospital admission for continuous fetal monitoring if symptoms persist 2

LOWER RISK (Outpatient Management Possible)

• Musculoskeletal pain without peritoneal signs 6
• Pain improving with position changes or activity modification 7
• Normal vital signs and reassuring fetal status 6

Action: Multimodal analgesia with acetaminophen 650 mg every 6 hours or 975 mg every 8 hours as first-line; ibuprofen 600 mg every 6 hours if not contraindicated 6

Special Considerations by Gestational Age

Second Trimester

• Placenta previa assessment: If placenta crosses internal cervical os by ≥15 mm at 20-23 weeks, repeat ultrasound later in pregnancy 2
• Cervical length monitoring: Short cervix with vaginal bleeding significantly increases preterm delivery risk 2

Third Trimester

• Serial growth monitoring: Every 2-4 weeks if receiving treatment that may affect fetal growth 2, 4
• Delivery planning: Avoid elective repeat cesarean before 39 weeks unless clear medical indication (increases neonatal respiratory complications) 4

Critical Pitfalls to Avoid

• Never dismiss pain localized over the cesarean scar as "normal"—this symptom doubles uterine rupture risk and requires thorough evaluation 1
• Do not delay evaluation beyond 48 hours if internal herniation is suspected in bariatric surgery patients—all maternal/fetal deaths occurred with delayed treatment 2
• Persistent severe pain at any postpartum timepoint is NOT normal and requires investigation for complications including perforation, abscess, or retained tissue 6, 5
• Avoid proceeding with trial of labor without immediate surgical capability for emergency cesarean if rupture occurs 4
• Do not assume pain is musculoskeletal without excluding obstetric emergencies first—multiple pain mechanisms can coexist 6

When to Deliver

• Emergency delivery indicated for: Confirmed or highly suspected uterine rupture, placental abruption with fetal compromise, maternal hemodynamic instability 2
• Planned delivery considerations: If APAP persists and rupture cannot be excluded, delivery timing should balance fetal maturity against maternal/fetal risk 1
• Epidural anesthesia preferred for cesarean section to avoid endotracheal trauma if emergency conversion needed 2