Interstitial Molar Ectopic Pregnancy Despite Euploid Embryo Transfer: A Case Report

BACKGROUND: Even with modern in vitro fertilization (IVF) techniques, unexpected pregnancy outcomes can occur. Molar pregnancy after IVF and embryo transfer can be the result of true abnormal fertilization in the embryology lab. Preimplantation genetic testing for aneuploidies (PGT-A) has advanced and is widely used, but unless additional testing of single-nucleotide polymorphisms is performed, the rare case of partial molar pregnancy (defined as triploidy of paternal origin) after IVF may be missed. Unexpected pregnancy outcomes may also be a result of spontaneous fertilization during assisted reproductive technology (ART) treatment. CASE: The patient is a 36-year-old G1P100 who initially underwent IVF and intracytoplasmic sperm injection with PGT-A and preimplantation genetic testing for monogenic disorders for galactosemia carrier status in both partners. After obtaining euploid and galactosemia unaffected embryos, she underwent a frozen embryo transfer of a female, euploid embryo. The result was a right interstitial molar ectopic pregnancy that was managed with laparoscopic right cornual resection. CONCLUSION: Assisted reproductive technology with PGT-A attempts to eliminate the risk of abnormal embryo transfer. Technical factors, such as variations in testing processes among PGT-A laboratories, and human factors, such as unprotected intercourse during ART, contribute to unexpected pregnancy outcomes.