Challenges in the Diagnosis of secondary abdominal pregnancy - Unusual presentation with anhyramnios

Siewchee Wong1, Gillian Coleman1, Amita Mahendru2, 1Obstetrics Nottingham University Hospital NHS Trust, 2Fetal Medicine Nottingham University Hospitals NHS Trust


Abdominal pregnancy is a rare form of ectopic pregnancy associated with higher maternal mortality rate than tubal ectopic pregnancies. Ruptured rudimentary horn pregnancy is one of the rarest forms encountered and this case highlights the challenges encountered in dealing with it.

Case Report

A lady presented to fetal medicine in her second pregnancy with anhydramnios at 19+5 weeks gestation, with normal fetal kidneys and bladder. She had one previous emergency caesarean section for footling breech, and the intraoperative notes at that time suggested evidence of bicornuate uterus, with the pregnancy in the right horn. Throughout third trimester in this pregnancy, she reported persistent lower abdominal pain and MRI at 30 weeks reported didelphic uterus, with fetus noted in the left horn and possible tracking of fluid outside the uterus. This led to the concern of possible scar dehiscence or possible rudimentary horn pregnancy. In view of this, a planned caesarean section was carried out at 32 weeks that led to the diagnosis of abdominal pregnancy. A unicornuate uterus with only right ovary and tube was noted intraoperatively. The baby was diagnosed with bilateral congenital hip dislocation requiring surgery but was otherwise well. Placental histology confirmed the presence of myometrium, salpinx and ovary in keeping with ruptured rudimentary horn pregnancy.


Undiagnosed ruptured rudimentary horn pregnancy in unicornuate uterus is a very rare cause amongst the various causes of secondary abdominal pregnancy. In spite of advances in ultrasound imaging and MRI, these cases are still seen. Even if diagnosed antenatally, counselling and management is difficult in the presence of a live extrauterine pregnancy.


Careful assessments of fetus, uterus and adnexa in early pregnancy in cases with uterine anomalies and developing expertise in the use of MRI may enable early diagnosis in these challenging situations.

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