In a first‑trimester pregnant patient with pelvic pain after lifting a 5‑gallon water container, what is the appropriate next step?

First-Trimester Pelvic Pain After Lifting: Next Steps

The next step is to perform a transvaginal ultrasound immediately to exclude ectopic pregnancy, placental abruption, and other obstetric emergencies, while simultaneously assessing hemodynamic stability with vital signs. 1, 2

Immediate Assessment Priorities

Hemodynamic evaluation comes first. Check vital signs immediately, as tachycardia is a significant predictor of serious complications in pregnant patients. 1, 2 Establish IV access if any signs of instability are present. 1

Key vital signs to assess:

• Tachycardia, fever, and tachypnea together should raise immediate concern for serious complications 2
• Hypotension may indicate hemorrhage from ectopic rupture or placental abruption 3

Essential Laboratory Studies

Obtain urgently:

• Quantitative β-hCG to assess for ectopic pregnancy 1, 2
• Blood type and Rh status for potential anti-D immunoglobulin administration 1
• Complete blood count and coagulation profile 3
• Urinalysis to exclude urinary tract infection or urolithiasis 2

Critical pitfall: Never assume normal pregnancy based on low β-hCG alone without ultrasound confirmation, and do not defer ultrasound because β-hCG is "too low"—this delays diagnosis of ectopic pregnancy. 1

Imaging Approach

Transvaginal ultrasound is the first-line imaging modality and should be performed even when β-hCG is below traditional discriminatory thresholds. 1, 2 This is superior to transabdominal ultrasound for first-trimester evaluation. 4

The ultrasound must systematically evaluate:

• Intrauterine pregnancy confirmation (primary focus) 4
• Uterus traced from fundus to cervix in two orthogonal planes 4
• Ovaries in short and long axis to identify masses, cysts, or torsion 4
• Cul-de-sac for free fluid (large amounts suggest possible ectopic rupture) 4
• Fetal heart rate if intrauterine pregnancy is visualized 3

If ultrasound is inconclusive, proceed to MRI without contrast rather than CT to minimize radiation exposure. 1, 2 MRI has 97% sensitivity and 95% specificity for diagnosing appendicitis in pregnancy. 1, 2

Differential Diagnosis in This Context

Trauma-Related Obstetric Causes

Even though lifting a 5-gallon container (approximately 40 pounds) represents blunt abdominal trauma, the following must be excluded:

• Placental abruption (ultrasound sensitivity only 40-50%, so normal imaging doesn't exclude it) 3
• Threatened abortion from trauma 2
• Uterine injury (rare in first trimester due to pelvic protection) 3

Non-Traumatic Obstetric Causes

• Ectopic pregnancy (critical diagnosis in any first-trimester patient with pain, especially with any vaginal bleeding) 1, 2
• Normal uterine stretching and round ligament pain 2

Non-Obstetric Causes

• Ovarian torsion (diagnosed by ultrasound showing enlarged ovary with decreased/absent Doppler flow) 3, 2
• Ovarian cyst rupture or hemorrhage 4
• Appendicitis (most common cause requiring emergency surgery in pregnancy) 1, 2
• Urolithiasis or pyelonephritis 2

Occupational Lifting Context

This patient exceeded safe lifting limits for first trimester. Clinical guidelines recommend maximum lifting of 36 pounds for infrequent lifting in the optimal zone (knuckle to shoulder height, close to body) before 20 weeks gestation. 4 A 5-gallon water container weighs approximately 40 pounds, exceeding this threshold.

No lifting from floor level is recommended due to torso flexion risk, and no overhead lifting due to postural instability risk. 4 Frequent bending at the waist >1 hour daily shows nearly 3-fold increased risk of preterm labor and spontaneous abortion. 4

Disposition and Follow-Up

If ultrasound is indeterminate, arrange concrete follow-up within 24-48 hours before discharge—this is mandatory, not optional. 1

Administer anti-D immunoglobulin (RhoGAM) if patient is Rh-negative and has threatened abortion, complete abortion, or ectopic pregnancy. 1

Discharge criteria (all must be met):

• Tolerating oral intake 2
• Pain controlled with oral analgesia 2
• Stable vital signs 2
• No peritoneal signs 2
• Reliable follow-up arranged 2

Critical Red Flags Requiring Immediate Intervention

• Severe pain with hemodynamic instability 2
• Vaginal bleeding with abdominal pain 2
• Fever with abdominal pain (suggests infection) 2
• Peritoneal signs (rigid abdomen, rebound tenderness) 2

Position the patient in left lateral tilt if she requires prolonged evaluation or procedures, as supine positioning after first trimester can compress the inferior vena cava, causing maternal hypotension and decreased placental perfusion. 1