This blog post comprises of important points taken from the TOG article ‘Advanced abdominal pregnancy’ published in July 2022. It is strongly recommended to read the full article to have a complete understanding of this topic as this post is just a quick summary.
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Introduction
- Abdominal pregnancy — when implantation occurs within abdominal cavity / an extra uterine pregnancy in which all or most of the foetus develops within the abdominal cavity
- A rare form of ectopic pregnancy
- Incidence ~1% of all ectopic pregnancies
- Associated maternal mortality 0-12%
- Overall risk of maternal death 7x that of ectopic pregnancy 90x that of an intrauterine pregnancy
- Fetal survival >78%
Classification
Based on gestation at diagnosis
- Early Abdominal Pregnancy (EAP) - before 20 weeks
- Advanced Abdominal Pregnancy (AAP) - after 20 weeks
Based on site of implantation
- Primary abdominal pregnancy — implantation directly occurs in the abdominal cavity
- Secondary abdominal pregnancy — when conception extruded from its primary site of implantation and re-implants in abdominal cavity (usually after ruptured ectopic)
Risk Factors
- Most have no identifiable risk factors
- Risk factors are same as any other ectopic pregnancy — tubal pathology, in situ IUCD, previous ectopic
- Uterine anomalies & history of previous uterine surgery (esp CS) are associated with abdominal pregnancy
- AAP can also occur post scar rupture, previous myomectomy and post uterine perforation at surgical TOP, after IVF
Clinical Presentation
- Diagnosis is often missed & usually made after fetal demise
- Only 50% diagnosed before surgery
- High suspicion is key to pre-operative diagnosis
- No specific S&S of AAP
Symptoms
- Commonest presentation — abdominal pain ± vaginal bleeding (pain often persistent & increases by fetal movements)
- Bloating & vomiting
Signs
- None pathognomonic
- Reasonable sign of AAP - displaced cervix (anteriorly)
- Others— severe anaemia, abnormal fetal lie, oligohydramnios, SGA
Ultrasound
- Abdominal pregnancy hard to diagnose with advancing gestation
- Any first-trimester scan should include - location of gestational sac in relation to cervix, endometrial cavity and uterus
- Intraabdominal pregnancy suspected on USG — extrauterine amniotic sac & an empty uterine cavity - foetus & placenta outside uterus, lack of uterine myometrium around foetus
- Skills & techniques of sonographer matters