BACKGROUND AND PURPOSE: 

• There have been reports in the literature that ovulation is more frequent in the right ovary and fertility from oocytes derived from the right ovary may be superior to those on the left  
• While research is available related to ovulation, there is minimal data on whether there is similar asymmetry in the setting of ectopic pregnancy  
• Wei Xia et al. (JMIG, 2018) investigated whether there are left-right asymmetries in tubal pregnancies (TP)

METHODS: 

• Retrospective study (2005-2016) 
• Participants  
  • Women diagnosed with ectopic pregnancies
• Data collection included  
  • Demographic characteristics | Reproductive, gynecological and surgical history | Clinical features such as abdominal pain and hCG levels | Treatment

RESULTS: 

• 6,186 patient charts with TP were included  
• The overall frequency of right-sided TP was 54.48% (3,370/6,186) 
  • Significantly higher than the expected 50% (P <0.001) 
• The proportion of right-sided TP
  • Decreased with age (P for trend = 0.007)  
  • Decreased from the proximal (interstitial) end to the distal (fimbrial) end of the tube (P for trend = 0.017) 
• If a corpus luteum was present, it was
  • More common on the right ovary (P <0.001)  
  • Located in the contralateral ovary to the TP side in 41.38% of cases 
• Tubal rupture more frequent in left TP (4.26%) vs right TP (2.94%); (P = 0.005)

CONCLUSION: 

• The authors recognize the limitations of this study, specifically retrospective design that would allow for biases 
• This study did detect right sided asymmetry/dominance in ectopic (tubal) pregnancies 
• Clinical feature differences were also observed, with more frequent tubal ruptures in left side TP 
• Underlying mechanisms still unknown, but authors hypothesize that 
  • Right sided ovulation appears more frequent 
  • There is a difference between left (left renal vein) and right ovarian (IVC) venous drainage 

Learn More – Primary Sources: 

Left-right asymmetry of tubal pregnancy: a 12-year retrospective hospital-based study 

Related ObG Topics:

Diagnosing the Extrauterine Pregnancy-What You Need to Know

Pregnancy of Unknown Location – Next Steps

You’ve Diagnosed the Ectopic Pregnancy – When and How to Use the Medical Option