Ectopic Pregnancy

Etiology and Risk Factors

The development of this pathology is directly linked to conditions and diseases that directly or indirectly impair the normal transport of the fertilized ovum through the fallopian tubes. Several main groups of causes are identified:

• Inflammatory diseases of the uterine adnexa. This is the leading cause, ranking first. Previous acute salpingitis promotes adhesion formation and narrowing of the fallopian tube lumen. As a result, the risk of ectopic implantation increases 6- to 7-fold compared to the healthy population.
• Hypoplasia of the corpus luteum of the ovary. Identified in nearly half of the cases, often combined with preexisting structural pathology of the fallopian tubes.
• Iatrogenic factors. The risk increases significantly following reconstructive plastic surgeries on the fallopian tubes (probability rises to 6–27% depending on the type of surgical intervention). Another trigger can be ovulation induction during the treatment of endocrine infertility or in vitro fertilization (IVF), which increases the risk up to 10%.
• Embryonic factor. If the trophoblast develops and differentiates too rapidly, it causes premature implantation of the blastocyst before it reaches the uterus.
• Rare causes. Include uterine malformations, the use of intrauterine devices (IUDs), and certain types of hormonal contraception.

Outcomes of Tubal Pregnancy

Since fallopian tubes account for up to 99% of all cases, their pathology has been studied most thoroughly. Due to embryo invasion into the thin wall not intended for placentation, the pregnancy terminates. This occurs in two ways:

1. Fallopian tube rupture. The ovum literally bursts through the tissues and enters the abdominal cavity. Clinically, this manifests as sharp abdominal pain, dizziness, and signs of collapse caused by massive internal bleeding. This is a critical condition requiring immediate surgical intervention.
2. Tubal abortion. In this case, the ovum detaches from the tubular wall and is expelled into the abdominal cavity via antiperistaltic contractions. If the embryo, placenta, and clusters of blood clots are retained within the tubal lumen, it is termed an incomplete tubal abortion.

Abdominal Pregnancy

This is an extremely severe condition with a poor prognosis. There is a constant threat to the mother of gestation sac rupture and fatal hemorrhage, while the fetus inevitably dies under such conditions. Patient survival is possible only in rare cases where internal bleeding does not assume a catastrophic character.

Abdominal pregnancy is classified into two forms:

• Primary: absolute medical rarity. Characterized by the initial implantation of the ovum directly onto abdominal organs (peritoneum, greater omentum, liver, spleen, or stomach).
• Secondary: occurs somewhat more frequently. Arises as a direct consequence of a tubal abortion or tubal rupture, when a viable ovum falls into the abdominal cavity and implants there secondarily.

Pathomorphological Picture of Ectopic Pregnancy

Morphological diagnosis of tubal pregnancy generally presents no difficulties for the pathologist.

• Macroscopic appearance: the resected fallopian tube appears locally expanded in a specific segment. Upon opening it, the ovum is visualized within the lumen, surrounded by masses of clotted blood (massive hemorrhage).
• Microscopic appearance: standard histological examination (hematoxylin and eosin staining) reveals extensive hemorrhages in the fallopian tube wall, alongside clearly identifiable chorionic elements—trophoblast cells invading the underlying tissues.

Examination of Uterine Cavity Material (Differential Diagnosis)

To confirm pregnancy localization or verify a spontaneous uterine abortion, a histological examination of material obtained from uterine curettage is performed.

In most cases, intact embryos are not preserved, and only fragments of decidual tissue and chorionic villi are received for analysis. In the event of uterine pregnancy termination, microscopic examination reveals:

• Foci of decidual tissue necrosis with marked neutrophil infiltration.
• Thrombi in decidual blood vessels.
• Foci of hemorrhages of varying volumes.
• Edematous chorionic villi lacking their own blood vessels (avascular).

Important: The goals of this examination are to prove the fact of pregnancy, estimate the approximate gestational age of the abortion based on villous structure, and rule out gestational trophoblastic disease. If only decidual tissue without chorionic villi is found in the curettage, this may indirectly indicate the presence of an ectopic pregnancy.