Morphology of the fallopian tube in pregnancy
When pregnancy develops outside the uterine cavity, particularly in the fallopian tube, specific histological changes are observed. Chorionic villi deeply penetrate the tubal wall, reaching the thickness of its muscular layer. Extravillous trophoblast cells as well as fibrinoid deposits are found in these tissues. Unlike the endometrium, the decidual reaction in the mucosa of the fallopian tubes is weakly expressed and insignificant in nature.
Gestosis: epidemiology and risk factors
Gestosis (formerly referred to as "late toxicosis of pregnant women") is the most frequent pathology whose development is directly associated with the presence of pregnancy. In global practice, a unified terminology for this condition is still lacking. The disease is classified according to its severity, with eclampsia being its most severe form.
There is also combined gestosis—a pathology that occurs in pregnant women against the background of pre-existing somatic diseases. On average, the incidence of gestosis ranges from 10–15%, though some studies indicate figures up to 30%.
The main risk factors for the development of gestosis include:
- Excess body weight (obesity).
- Kidney diseases.
- Arterial hypertension and concomitant pathologies.
- Unfavorable social and living conditions.
- Patient age: the risk increases in pregnant women under 17 and over 30 years of age.
Pathogenesis: gestational transformation of spiral arteries
The exact etiology of gestosis remains not fully elucidated, but it is reliably known that the disease is driven by the presence of placental tissue: delivery of the placenta leads to the cessation of the disease. Impaired trophoblast invasion processes are considered the basis of pathogenesis.
Physiological norm During a normal pregnancy, extraplacental trophoblast deeply invades the endometrium and myometrium. Gestational transformation of the spiral arteries occurs: their muscular and elastic walls are destroyed and replaced by a wide layer of fibrinoid. Invasive extravillous trophoblast cells accumulate around the artery within the decidual tissue. As a result, the vessel diameter increases by 10–15 times. The loss of the muscular layer makes these arteries unresponsive to vasoconstrictor substances circulating in the maternal blood, which ensures a stable and adequate blood supply to the placenta.
Pathology in gestosis In gestosis, trophoblast invasion into the endometrium and myometrium is impaired. Gestational transformation of the spiral arteries does not occur. Histologically, the vessel lumen remains narrow, and the layers of the vascular wall (muscular and elastic) remain preserved—fibrinoid necrosis and trophoblast invasion are absent. Against the background of these changes, atherosis may develop—a specific vascular pathology characterized by excessive accumulation of fibrinoid and the presence of numerous lipid-laden foam cells.
Humoral disorders and systemic vascular spasm
The lack of gestational transformation and the narrow lumen of the spiral arteries lead to a biological compensatory reaction. The body attempts to increase blood pressure and enhance blood flow to the placenta to prevent fetal hypoxia.
Vascular morphological insufficiency causes placental ischemia, which provokes an acute imbalance of vasoactive substances in the pregnant woman's body:
- Secretion of vasoconstrictor factors increases: thromboxane A2, prostaglandin F, angiotensin, and endothelin are actively released into the blood.
- Production of vasodilatory agents decreases: levels of prostacyclin (prostaglandin I2), prostaglandin E, and nitric oxide drop.
The consequence of such a humoral shift is the development of generalized vascular spasm in the woman, which acts as the main link in the clinical picture of gestosis.
Briefly: answers to topical questions
What are the main morphological signs of spontaneous abortion in a uterine cavity curettage specimen?
The main morphological sign of interrupted intrauterine pregnancy in a uterine cavity curettage specimen is the presence of decidual tissue with chorionic villi. This sign has differential diagnostic significance: in ectopic pregnancy, the uterine cavity curettage reveals decidual tissue without chorionic villi / absence of chorionic villi in the presence of a decidual reaction and/or the Arias-Stella phenomenon.
Which chromosomal abnormalities are most frequently the cause of early spontaneous abortion?
The leading cause of embryonic death in the first weeks of pregnancy is chromosomal aberrations. Among chromosomal abnormalities in aborted materials, the following disorders are most frequently found:
- Autosomal trisomies—identified in 45–55% of cases.
- Monosomy 45,X (Turner syndrome)—accounts for 20–30% of all anomalies.
- Triploidy—diagnosed in 15–20% of cases.
- Tetraploidy—occurs less frequently, accounting for about 5%.
The frequency of detecting an abnormal karyotype is maximal at 6–7 weeks (60–75%) and gradually decreases with increasing gestational age.
What clinical and morphological stages are distinguished in spontaneous abortion?
In spontaneous abortion, five stages of pregnancy interruption are distinguished:
- Threatened abortion—the connection between the gestational sac and the uterine wall is preserved, uterine tone is elevated.
- Inevitable abortion—detachment of the gestational sac from the uterine wall occurs.
- Abortion in progress—the gestational sac completely detaches from the uterine wall and descends into its lower parts, including the cervical canal.
- Complete abortion.
- Incomplete abortion—the state after expulsion of the gestational sac, in which its remnants are retained in the uterine cavity, usually fetal membranes, parts of the chorion/placenta.
How does complete spontaneous abortion morphologically differ from incomplete abortion?
According to the cited sources, for incomplete abortion, it is indicated that after expulsion of the gestational sac, its remnants are retained in the uterine cavity—usually fetal membranes, parts of the chorion/placenta. Ultrasound may visualize remnants of the gestational sac, and the pregnancy test (β-hCG) may remain positive.
Complete abortion is named in the sources as one of the stages of spontaneous abortion, but its detailed morphological features are not disclosed in the provided materials.
Class and exam questions
What is the essence of the pathogenesis of gestosis at the tissue level?
The essence lies in impaired trophoblast invasion, as a result of which spiral arteries fail to transform, retain their muscular layer and narrow lumen, leading to placental ischemia.
What are the humoral consequences of placental ischemia?
Ischemia causes an imbalance of vasoactive substances: the synthesis of vasoconstrictor factors (thromboxane A2, angiotensin) sharply increases, while vasodilators (nitric oxide, prostacyclin) drop.
What else to study on this topic
- Morphological differences of extravillous trophoblast during normal invasion
- Histological picture of spiral artery atherosis
- Mechanisms of generalized vascular spasm formation
- Morphological manifestations of eclampsia in target organs
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