What could be causing cramps and a feeling of impending menstruation at 5 weeks and 5 days of pregnancy?

Cramping at 5 Weeks 5 Days of Pregnancy

Mild cramping and a sensation similar to impending menstruation at 5 weeks 5 days of pregnancy is common and usually represents normal physiologic changes as the uterus expands and the pregnancy implants, but requires immediate evaluation with transvaginal ultrasound and quantitative β-hCG to exclude ectopic pregnancy, threatened miscarriage, or early pregnancy loss. 1

Immediate Diagnostic Evaluation Required

You must obtain transvaginal ultrasound and quantitative β-hCG immediately—do not defer imaging based on gestational age or assume symptoms are benign. 2, 3

Critical Ultrasound Findings at This Gestational Age

At 5 weeks 5 days, transvaginal ultrasound should reveal:

• A gestational sac (2-3 mm mean sac diameter) with hyperechoic rim located in the upper two-thirds of the uterine cavity 1
• A yolk sac may be visible at this gestational age (typically appears around 5½ weeks) 1, 4
• An embryo is NOT yet expected—cardiac activity typically develops at 6 weeks 2
• If no intrauterine gestational sac is visible, you must actively exclude ectopic pregnancy 1, 2

β-hCG Correlation

• Most intrauterine pregnancies are visible when β-hCG reaches 1,000-3,000 mIU/mL 1, 4
• If β-hCG is ≥3,000 mIU/mL without a visible gestational sac, ectopic pregnancy is highly likely and requires immediate specialty consultation 1, 4
• However, 22% of ectopic pregnancies present with β-hCG <1,000 mIU/mL, so never defer ultrasound based on "low" β-hCG levels 2, 4

Differential Diagnosis by Clinical Presentation

If Cramping is MILD Without Bleeding

This likely represents normal uterine stretching and implantation changes, but confirmation with ultrasound is mandatory. 1, 5

• Normal physiologic cramping occurs as the uterus expands and ligaments stretch 5, 6
• Implantation-related discomfort can mimic menstrual cramping 1
• However, you cannot distinguish normal from pathologic cramping by symptoms alone 2, 3

If Cramping is Accompanied by Vaginal Bleeding

Bleeding with cramping at 5 weeks 5 days occurs in 7-27% of pregnancies and carries approximately 12% overall miscarriage risk. 1, 3

The differential includes:

• Threatened abortion (viable pregnancy with bleeding)—most common outcome 1, 3
• Early pregnancy loss/spontaneous abortion 1, 3
• Ectopic pregnancy (7-20% of pregnancy of unknown location cases) 2, 3
• Subchorionic hematoma with viable pregnancy 3

If Cramping is SEVERE or Unilateral

Severe or unilateral pain raises significant concern for ectopic pregnancy and requires emergent evaluation. 2

• Unilateral adnexal tenderness is present in 70-80% of ectopic pregnancies 2
• Ectopic pregnancy can rupture at any β-hCG level, including very early in pregnancy 2, 4
• Shoulder pain suggests hemoperitoneum from ruptured ectopic and requires immediate surgical consultation 4

Management Algorithm

Step 1: Obtain Transvaginal Ultrasound and β-hCG Immediately

Never perform digital pelvic examination before ultrasound imaging. 3

Step 2: Interpret Results

If intrauterine gestational sac with yolk sac is confirmed:

• This is definitive evidence of intrauterine pregnancy and essentially excludes ectopic pregnancy (except rare heterotopic pregnancy in <1% of spontaneous conceptions) 1, 3, 4
• Schedule follow-up ultrasound in 1-2 weeks to confirm cardiac activity 3
• Reassure patient that mild cramping is normal but counsel about warning signs 3

If gestational sac is seen but no yolk sac yet:

• This is consistent with very early pregnancy (4.5-5 weeks) 1
• Repeat ultrasound in 7-10 days to confirm progression 4
• Obtain serial β-hCG every 48 hours—should double in viable pregnancy 3, 4

If no intrauterine pregnancy is visible (pregnancy of unknown location):

• Obtain serial β-hCG measurements every 48 hours until diagnosis is established 3, 4
• Repeat transvaginal ultrasound when β-hCG reaches 1,500-3,000 mIU/mL 3, 4
• Arrange immediate specialty consultation or close outpatient follow-up 2, 3
• 80-93% will be early or failed intrauterine pregnancies, but 7-20% will be ectopic 3, 4

If extraovarian adnexal mass or tubal ring is identified:

• This has a positive likelihood ratio of 111 for ectopic pregnancy 2, 4
• Obtain immediate gynecology consultation for surgical or medical management 4

If free fluid in pelvis, especially with internal echoes:

• This is concerning for ruptured ectopic pregnancy 2
• Assess hemodynamic stability and obtain emergent surgical consultation 2

Critical Warning Signs Requiring Immediate Return

Instruct the patient to return immediately for:

• Severe or worsening abdominal pain 2, 5
• Shoulder pain (suggests hemoperitoneum) 4
• Heavy vaginal bleeding (soaking >1 pad per hour) 3
• Dizziness, lightheadedness, or syncope (suggests hemorrhage) 2
• Fever (suggests infection) 6

Common Pitfalls to Avoid

• Never assume cramping is "normal" without ultrasound confirmation of intrauterine pregnancy 1, 2
• Never defer ultrasound based on gestational age being "too early"—ectopic pregnancies can rupture at any stage 2, 4
• Never use β-hCG level alone to exclude ectopic pregnancy 2, 4
• Never perform digital pelvic examination before excluding placental abnormalities with ultrasound 3
• Never discharge a patient with pregnancy of unknown location without ensuring reliable follow-up 2
• Avoid overinterpretation of a single ultrasound that could lead to inappropriate treatment potentially harming a normal early pregnancy 1, 3

If Cramping Persists After Confirming Normal Intrauterine Pregnancy

Once ectopic pregnancy and miscarriage are excluded:

• Reassure that mild cramping is common in early pregnancy due to uterine expansion and ligament stretching 5, 6
• Cramping typically improves as pregnancy progresses into the second trimester 5
• No specific treatment is required for physiologic cramping 5