Post term pregnancy is an increase in gestation to 42 weeks or more, leading to delayed delivery and the birth of a fetus with signs of over-maturity. Disease is accompanied by dehydratacea – a decrease in the amount of amniotic fluid, a decrease in body weight in a pregnant woman, signs of aging of the placenta, compaction of the skull bones in the fetus, fetal hypoxia. Diagnostics according to anamnesis, ultrasound results, cardiotocography, amnioscopy. Post term pregnancy requires an amniotomy, medical stimulation of labor activity or operative delivery.
ICD 10
O48 Post term pregnancy
General information
The average duration of a physiological pregnancy is 40 weeks or 280 calendar days from the beginning of the last menstruation. This time is sufficient and optimal for the development of a mature fetus capable of extrauterine existence. After 40 weeks of gestation, disease is judged not by calendar dates, but by the state of the placenta, fetus and fetoplacental blood flow. Therefore, when extending the gestation period by 10-14 days in obstetrics and gynecology, prolonged and post term pregnancy are distinguished.
Prolongation of physiological pregnancy is considered to increase the gestation period to 290-294 days in the absence of signs of aging of the placenta and overripe fetus. With true perenashivaniye, pregnancy ends with the birth of an overripe fetus with morphofunctional changes in the placenta. Signs include a decrease in the amount of amniotic fluid, the absence of primordial lubrication, wrinkling and dryness of the baby’s skin, the appearance of meconium impurities in the waters, as a result of which their color becomes grayish or greenish.
Post term pregnancy occurs in about 4% of cases. The danger of a post term pregnancy lies in the high probability of complicated labor, operative delivery, and an unfavorable outcome of labor.
Causes
Numerous factors that negatively affect a woman’s reproductive function can serve as a background for a post term pregnancy. Post term pregnancy often occurs in women with menstrual dysfunction (early or late menarche, irregular menstruation, menstrual cramps), sexual infantilism. Childhood infections – measles, scarlet fever, mumps, rubella, etc., as well as flu or SARS suffered during the present pregnancy, may adversely affect the course of pregnancy in the future.
Among the causes of delayed pregnancy, endocrine diseases of women (thyroid disorders, diabetes mellitus, etc.), gastrointestinal diseases, liver are often noted. These conditions can disrupt hormonal metabolism and cause inertia of the uterus, its reduced excitability. Inflammation of the reproductive organs (adnexitis, endometritis, cervicitis), uterine tumors (fibroids, fibroma), ovarian dysfunction, gestosis, artificial termination of pregnancy in the anamnesis can also lead to changes in the neuromuscular regulation of uterine activity.
Disease may be due to insufficient physical activity, prolonged bed rest, mental trauma and emotional turmoil experienced by a woman. In addition to all of the above, pregnancy is facilitated by drug therapy with the threat of miscarriage, previous childbirth with a large fetus, the first birth over the age of 30, pelvic presentation of the fetus, pathology of the previous pregnancy. It is possible that a post term pregnancy may be caused by fetal diseases, primarily by malformations of the central nervous system (hydrocephalus, anencephaly, microcephaly), Down’s disease, polycystic kidney disease, adrenal pathology, etc.
Since the onset, course of pregnancy and development of labor involve complex mechanisms involving the central nervous system, hormones (estrogens, progestogens, glucocorticoids, hCG, acetylcholine, catecholamines, serotonin, histamine), enzymes, electrolytes, trace elements and vitamins, virtually any failure in the neuroendocrine regulation system can serve as an impetus for a post term pregnancy.
Symptoms
The post term pregnancy is indicated, first of all, not by the excess of the chronological terms of gestation, but by changes on the part of the placenta and fetus. With a post term pregnancy after 290 days of gestation, a woman has a decrease in abdominal volume by 5-10 cm, and body weight by 1 kilogram or more, which is due to a decrease in amniotic fluid. Against this background, the pregnant woman’s skin turgor decreases, there is an increased density of the uterus and immaturity of the cervix. There may be a discharge of milk from the nipples instead of colostrum.
Conducting a vaginal examination in a patient with a post term pregnancy reveals an increased density of the skull bones in the fetus, narrowness of the fontanelles and bone sutures. During abdominal auscultation, muffled fetal heart tones with an incorrect frequency and rhythm are heard, indicating fetal hypoxia. Objective confirmation of the diagnosis of a post term pregnancy can be obtained with the help of instrumental studies.
Diagnosis
The diagnosis begins with the clarification of the gestational period. To do this, the totality of the results of all the methods used is taken into account: counting from the date of the last menstruation (the Negele rule), the period of ovulation, fertilization, the first stirring, listening to heart tones, ultrasound data, etc.
An objective obstetric examination during post-term pregnancy reveals a decrease in the circumference of the abdomen along with a high standing of the uterine floor; a delay in the increase in the body weight of a pregnant woman or weight loss. Fetal mobility during post-term pregnancy decreases as a result of lack of water, and the fetus itself stops growing. Gynecological examination allows you to determine the compaction of the cranial bones of the fetus, the narrowing of the sutures and fontanelles on the head, the unavailability of the cervix for childbirth.
The picture of ultrasound examination in post-term pregnancy is characterized by a decrease in the total volume and a complete absence of “anterior waters”, the absence of flake-like inclusions of cheese-like lubricant in amniotic waters, the presence of meconium in the waters. Dopplerography of the uteroplacental blood flow determines the signs of aging of the placenta, which does not fully provide nutrition and oxygen supply to the fetus: petrifications in the placenta, a decrease in its thickness, reduced intensity of fetoplacental and uteroplacental blood flow. All these data indicate the overripe fetus and hypoxia experienced by it. Reduction of fetal heart rate (less than 110-120 beats. in min.) or increase (over 160 beats. in min.) according to the results of cardiotocography, violations in the fetal condition are confirmed.
To diagnose a post term pregnancy, the technique of cervical amnioscopy can be used – an endoscopic examination of the nature of amniotic fluid through an intact wall of the fetal bladder. The greenish color of the waters, indicating an admixture of meconium, indicates intrauterine fetal hypoxia. Amnioscopy can only be performed in situations where the cervix is soft and slightly open for the insertion of the device.
Finally, the fact of a post term pregnancy is confirmed after childbirth. An overripe fruit is characterized by a greenish coloration of the skin, the presence of maceration of the skin, a decrease or absence of a cheese-like lubricant, hypotrophy of subcutaneous fat, compaction of the skull bones. Examination of the afterbirth reveals a dark green color of the umbilical cord and fetal membranes, the presence of calcification sites (petrifications) in the tissues of the placenta.
Tactics of labor management
Pregnant women at 41 weeks of pregnancy are subject to hospitalization in the department of pathology of pregnant women, where, after further examination, the issue of delivery tactics is resolved. With a post term pregnancy, the development of spontaneous labor is possible, but in its absence, artificial labor is resorted to.
If the cervix is not ready, local administration of special hormonal gels is used for several days, under the influence of which the cervix softens and the cervical canal expands. Then therapy is prescribed to stimulate the contractile activity of the uterus. Natural childbirth during post-term pregnancy requires continuous monitoring of fetal cardiac activity (listening to the heartbeat, conducting fetal phonocardiography).
In a number of cases (with acute intrauterine fetal hypoxia, weakness of labor forces, clinically narrow pelvis, pelvic presentation of the fetus, the presence of a scar on the uterus, etc.), surgical delivery of women with a post term pregnancy is resorted to using vacuum extraction, the imposition of obstetric forceps or by caesarean section.
Complications
Childbirth accompanying a post term pregnancy can be complicated by a prolonged course, premature outpouring of water, the development of discoordinated labor, hypo- and atonic bleeding, infectious complications (endometritis, metrothrombophlebitis, mastitis). In the postpartum period, due to the reduced contractility of the uterus, a lochiometer often develops.
The dangers of a post term pregnancy for a child are possible fetal hypoxia and asphyxia of the newborn, the development of brain lesions, birth trauma, aspiration of meconium and amniotic fluid. The condition of children born from a post term pregnancy is aggravated by severe jaundice, hormonal crises, infectious skin lesions, neurological disorders. Subsequently, they often lag behind normal physical and mental development.
The management of pregnancy in patients who are at risk for overgrowth requires serious attention from an obstetrician-gynecologist. In case of non-delivery at the expected time, the pregnant woman must be hospitalized in a maternity hospital to clarify the timing of gestation, the condition of the fetus and to resolve the issue of delivery.