In a 12‑week pregnant woman with right‑sided abdominal pain and newly diagnosed tricuspid regurgitation, what is the differential diagnosis and appropriate management plan?

Management of 12-Week Pregnancy with Right-Sided Abdominal Pain and Tricuspid Regurgitation

Immediate Assessment Priority

The right-sided abdominal pain requires urgent evaluation for appendicitis, which is a surgical emergency in pregnancy, while the tricuspid regurgitation at 12 weeks is most likely physiologic and benign. These are two separate clinical issues that must be addressed independently with different levels of urgency.

Differential Diagnosis

For Right-Sided Abdominal Pain:

• Appendicitis - the most critical diagnosis to exclude, as surgery should be performed within 24 hours of diagnosis to minimize perforation risk 1
• Urolithiasis/nephrolithiasis - common in pregnancy, particularly right-sided due to physiologic hydronephrosis 2
• Ovarian torsion or cyst complications
• Round ligament pain - benign but diagnosis of exclusion
• Ectopic pregnancy - less likely at 12 weeks with confirmed intrauterine pregnancy

For Tricuspid Regurgitation at 12 Weeks:

• Physiologic/benign finding - mild TR occurs in 83.4% of fetuses in early second trimester and resolves in most cases by mid-trimester 3
• Ebstein's anomaly - congenital malformation that should be evaluated 4
• Atrial septal defect (ASD) - commonly associated with TR 4
• Genetic/chromosomal abnormalities - particularly if TR is moderate to severe 5
• Dilated cardiomyopathy - rare but serious, may present with severe TR 5

Diagnostic Workup

For Right-Sided Abdominal Pain (URGENT):

Immediate laboratory assessment:

• Complete blood count with differential (looking for leukocytosis) 2
• Comprehensive metabolic panel 2
• Urinalysis with culture 2
• Temperature, heart rate, blood pressure 2

Imaging algorithm:

1. First-line: Ultrasound - initial diagnostic imaging for both appendicitis and renal pathology 1, 6, 2
2. Second-line: MRI without contrast - if ultrasound is inconclusive, MRI is the preferred modality per the American College of Radiology 1, 6, 2
3. Consider delayed repeat ultrasound during observation period, which can increase diagnostic yield to 58% without compromising safety 1

For Tricuspid Regurgitation:

Fetal echocardiography assessment:

• Detailed anatomic survey of cardiac structures to exclude Ebstein's anomaly, ASD, and other structural defects 4
• Assessment of TR severity (mild vs moderate vs severe) 3
• Evaluation of right ventricular function 4
• Ductus venosus flow assessment 3

Genetic testing considerations:

• If TR is moderate to severe: strongly consider cell-free fetal DNA testing from maternal blood sample 5
• If structural cardiac abnormalities are identified: genetic counseling and chromosomal microarray 5

Management Plan

For Right-Sided Abdominal Pain:

If appendicitis is diagnosed:

• Surgery within 24 hours to minimize perforation risk 1
• Laparoscopic appendectomy is preferred over open surgery and is safe during pregnancy 6
• Analgesia: Paracetamol (acetaminophen) 500-1000 mg every 6-8 hours, maximum 4 grams per 24 hours 6

If urolithiasis/hydronephrosis is diagnosed:

• Conservative management initially (succeeds in 70-80% of cases): adequate hydration, rest, antiemetics, acetaminophen for analgesia (avoid NSAIDs after 20 weeks) 2
• Proceed to urologic intervention if: pain refractory after 48-72 hours, fever/infection develops, significant obstruction with declining renal function, or persistent preterm labor signs 2
• Preferred intervention: retrograde ureteral stenting with ultrasound guidance (minimal fluoroscopy) 2

For Tricuspid Regurgitation:

If TR is mild and isolated:

• Reassurance - this is a benign, temporal finding in 83.4% of early second-trimester fetuses that resolves by mid-trimester in most cases 3
• Follow-up fetal echocardiography at 18-20 weeks to confirm resolution 3
• No intervention required 3

If TR is moderate to severe:

• Urgent genetic testing with cell-free fetal DNA analysis from maternal blood 5
• Detailed fetal echocardiography to exclude structural cardiac defects 4
• Genetic counseling regarding risk of dilated cardiomyopathy and other genetic conditions 5
• Serial monitoring with monthly or bimonthly echocardiography if structural abnormalities are identified 4

If Ebstein's anomaly is diagnosed:

• Risk stratification based on presence of cyanosis, heart failure, and right ventricular function 4
• Monthly or bimonthly cardiac evaluations including echocardiography for surveillance of RV function and arrhythmias 4
• Medical management of heart failure if it develops (even severe TR can usually be managed conservatively during pregnancy) 4
• Anticoagulation consideration if interatrial shunting is present due to risk of paradoxical emboli 4

Critical Pitfalls to Avoid

• Do not delay surgical evaluation for appendicitis - pregnancy does not increase susceptibility, but delayed diagnosis increases perforation risk 1
• Do not assume all TR is benign - moderate to severe TR warrants genetic testing and detailed cardiac evaluation 5
• Do not use NSAIDs for analgesia after 20 weeks gestation 2
• Do not dismiss right-sided pain as "normal pregnancy discomfort" without proper imaging workup 1, 2
• Do not perform CT as first-line imaging - ultrasound followed by MRI is the appropriate sequence 1, 6, 2