Local Defects of the Musculoskeletal System. Anomalies of Development and Pathology of the Placenta

Hemimelia — a group of defects accompanied with complete absence of distal parts of extremities at any level.

Ectodactilia — a claw-shaped hand or foot, a cleft hand or foot, аplasia of the central components of hand (or foot).

Polydictilia — presence of more than five digits on hand or foot.

Polyphalangism, polymelia, polychiria, polypodia — are supernumerary phalanges, extremities, hands and feet respectively.

Syndactilism — fusion of fingers or toes, involving soft parts only or including bone structure.

Synostosis — nondivision of bones.

The congenital dislocation of femur can be unilateral (in 20-25% of cases) and bilateral.

Congenital talipes — a stable adduction–flexion contracture of foot connected with disorder and shortening of internal and posterior group of ligaments of talocrural joint. It can be unilateral and bilateral. It is often combined with other congenital defects, including chromosomal and non-chromosomal syndromes.

Defects of Development of Skin and Its Appendages. These defects can be either isolated or combined with defects of other organs.

Hyperkeratosis — an excessive keratinization of skin of some parts of the body: palms, soles, a deflection surface of joints, etc. The defect is inherited by autosomal-dominant attribute.

Albinism — absence or significant reduction of melanin quantity in skin, hair, iris, therefore skin and hair have white colour, iris is red.

Rendu-Osler-Weber disease is a syndrome inherited by a dominant type, chracterizeded by presence on the skin, mainly of the face and extremities, of angiomas, 2-3 mm in diameter, as well as telangiectasias on mucous membranes of nose, in the field of red border of lips and in the liver, lungs, kidneys. Angiomas are quite often combined with aneurisms of cerebral and splenic arteries.

Hypertrichosis — excess of hair.

Atrichosis — absence of hair.

Defects of Development of Endocrine Glands. The congenital defects of development of endocrine glands are rarely encountered. Frequently revealed in children, died in perinatal or neonatal age, the morphological changes have a secondary character; they are caused by participation of endocrine organs in general adaptation syndrome and do not refer to defects of development.

Aplasia and hypoplasia of hypophysis, аplasia and hyperplasia of adrenal glands, agenesia of thyroid gland, aplasia of parathyroid glands are of certain practical significance.

Diseases of Intrauterine Fetus. To the most frequent pathological conditions of intrauterine fetus intrauterine fetal hypoxia (acute and chronic), haemolytic disease of the fetus (developing as a result of immunoincompatible pregnancy), syndrome of arrest of development of intrauterine fetus (due to feto-placental insufficiency), infection of intrauterine fetus. These conditions are described in detail in the appropriate chapters.

Anomalies of Development and Pathology of the Placenta. The form of the placenta depends on many factors, primarily on place of development of chorion and its interrelation with decidual membrane. Most frequently placenta has a circular form, either oval or elongated. Also placenta reniformis and placenta with additional lobules are encountered.

The ratio of the placenta weight to weight of the fetus is 1:5. The weight of the placenta at term is about 500–600 g, its thickness is about 1.5–2 cm, diameter — 15-20 cm.

In cases of different complications of pregnancy the structure, shape, size of the placenta usually change due to complications; the opposite situation is probable too: the pathology of the placenta leads to development of complications in pregnancy.

Additional placenta — there is an additional lobe of placenta in some remote part of amniotic membrane. Such additional lobes or additional placentas may be several. They incorporate into the main weight of the placenta with blood vessels. The lobes can be of various size: from a pea up to a large lobe. The additional lobes of the placenta can to be torn away in postpartum period and remain in the uterine cavity, causing bleeding. Diagnostics is based on detection of place of rupture of vessels leading to the additional lobe.

Multiple placenta is an anomaly, at which placenta is divided into three or more parts. In postpartum period the processes of separation and expulsion of such placenta proceed with remaining of its parts in the uterine cavity, which leads to expressed bleedings. Probable reasons of this anomaly of the placenta are heredity, atavism, character of nidation of fertilized ovum. Usually at such form of placenta there is a single vascular system of umbilical blood supply.

Fenestrated placenta, membranous placenta — an extremely rare pathology, its etiology is unknown. It is possible that one of the reasons is insufficient differentiation of chorionic tissues, insufficient vascularization of the remote sites of decidual membrane and destruction of part of villi in the early terms of pregnancy.

Thin placenta develops due to dystrophic and other changes in the endometrium (past inflammatory diseases, traumas connected with curettage of the uterine cavity). In such cases placenta becomes thin, but extensive.

Placenta marginata — a rare form of placenta anomaly, at which the edge of placenta rises like a border because of fibrin deposit.

Infarction of placenta — occurs due to disturbances of blood circulation, leading to necrosis of villi. In time the deposit of fibrin happens here. The infarction of placenta may be red and white. The fresh infarctions are of red color. After organization and deposition of fibrin, infarction of placenta takes the form of white spots of various size, located on the fetal and maternal surface. Sometimes infarctions get a large size and penetrate the whole thickness of placenta. The large infarcts can cause disturbances of development of fetus and even its intrauterine death.

Calcified placenta occurs due to deposit of salts in decidual sites of placenta; it is observed on the maternal surface and is a sign of placenta "aging". The fatty regenerations of sites of placental tissue are possible, resulting from failure of blood circulation.

Disturbances of placenta ripening are manifested by a complex of changes in all structural units of placenta: connective tissue and trophoblast, cellular membranes and system of blood circulation. Insufficiency of blood vascularization is of great importance. The reasons of these disturbances are not clearly known.

Most probable etiological factors are disturbed hormonal (estrogenic) stimulation, immune reactions in the feto-placental system in complicated course of pregnancy. A delayed and premature maturation (development) of placenta is distinguished.

The essence of delayed ripening of placenta consists in growth and branching out of mainly stromal villi. Placenta becomes large, but poor in terminal villi. This process is called a dissociated disorder of placenta development and is observed in rh-incompartibility, some forms of diabetes mellitus and some infectious diseases (syphilis, tоxoplasmosis).

The premature or early ripening of placenta occurs in case of normally formed placenta and differs in reduction of thickness of truncal villi and plenty of terminal villi. It is observed at gestoses of late pregnancy, common miscarriage, chronic pyelonephritis, etc. Disturbances of placental ripening lead to development of placental insufficiency and diseases of intrauterine fetus.

Four degrees of placenta maturity depending on density of echogenic structures in ultrasound examination are distinguished:

0 — placenta of homogeneous structure with a flat chorionic plate;

I — on a background of uniformity of placental structure there are small echogenic sites, chorionic plate becomes twisting;

II — echogenic sites in placenta become more intensive, the bends of chorionic plate penetrate the placental tissue, but do not reach the basal membrane;

III — the bends of chorionic plate reach the basal membrane forming circles; placenta acquires an expressed lobular structure.

The occurrence of the III degree of placental ripening before 38-39 weeks of pregnancy testifies to its premature maturing (aging of placenta) and is a sign of placental insufficiency.

The presence of the I-II degree of placental ripening after 37 weeks of pregnancy testifies to a delayed maturing of placenta and is a sign of placental insufficiency.

Tumors of placenta may be primary and secondary. To primary tumors of placenta angiomas located both on fetal and maternal surface of placenta refer. They develop from capillaries of chorionic villi. More often they develop in cases of hydramnion. Angioma does not affect the development of fetus.

Cancer and sarcoma of placenta are described as secondary tumors.

Cysts of placenta occur due to hemorrhages, regeneration of connective tissue, softening of infarction, degenerations of placental cells. Both small cysts being the size of a pea, and large cysts containing up to 0.25 ml of liquid of amber colour or sometimes colourless are distinguished. Subamniotic, subchorionic, dermoid cysts are known.