Clinics in obstetrics and gynaecology最新文献

Certain infections, such as UTI, may have an increased incidence during pregnancy owing to physiological changes. Between 2 and 10% of pregnant women have covert or asymptomatic bacteriuria which is associated with an increased incidence of acute symptomatic UTI in later pregnancy if left untreated. Thus antenatal screening to detect the presence of bacteriuria is justified. Most women will remain abacteriuric throughout the remainder of pregnancy after a single course of antibiotic therapy but a small percentage will fail to respond or have recurrent UTIs.

Maternal infection with certain organisms, namely those which resist phagocytosis, may result in transplacental infection of the fetus in utero. Congenital syphilis is preventable and antenatal serological screening is usually routinely performed. Listeriosis following maternal infection in pregnancy is less predictable and the epidemiology of L. monocytogenes remains unclear. Genital tract carriage of sexually transmitted organisms, such as N. gonorrhoeae or C. trachomatis, may also be detected during pregnancy and antibiotic therapy will be indicated to eradicate such organisms and prevent maternal and neonatal morbidity. Antibiotic therapy during pregnancy will not, however, eradicate carriage of GBS from the genital tract, although carriage status at term can now be reliably predicted by using enriched culture techniques and swabbing multiple sites on more than one occasion. Where carriage is confirmed, the administration of intrapartum antibiotics to the mother appears a useful approach in the prevention of early onset neonatal GBS disease. Broad spectrum intrapartum antibiotics may also be indicated when there are complications, such as prolonged labour or premature rupture of membranes, which are associated with a higher incidence of maternal postpartum endometritis and morbidity than in women following uncomplicated vaginal delivery. Serious postnatal sepsis and shock is fortunately now rare.

The pharmacokinetics of antibiotics in late pregnancy and the puerperium are altered and maternal serum levels may be reduced by 10–50%. Most antibiotics cross the placenta and are excreted in breast milk. Some agents, such as the beta-lactams, are considered safe in pregnancy and breast-feeding women while other antibiotics are contraindicated owing to risk of toxicity (often rare) or teratogenicity (often theoretical). Caution is necessary with many agents which may cause side effects or toxicity although this does not necessarily contraindicate their use in pregnancy. As with any therapy, antibiotic administration should not be undertaken without due consideration of the toxic potential of the agent used. The benefits of therapy should always outweigh the risks.

Preterm labour is a major cause of perinatal mortality and morbidity. The aetiology is multifactorial and attempts to predict preterm labour are unsuccessful. At the present time prophylaxis is unhelpful and the obstetrician must manage preterm labour as it arises. The management of pre term labour remains controversial because of the difficulty in conducting good clinical trials.

Antepartum glucocorticoids are effective in reducing the incidence and severity of respiratory distress syndrome. The effect is dependent upon a number of factors such as race, fetal sex, gestational age, state of the membranes, fetal asphyxia and timing of delivery in relation to therapy.

Tocolytics are effective in stopping contractions but this does not produce a significant prolongation of pregnancy or reduce perinatal mortality or morbidity. It is because they can suppress contractions and delay delivery for a short time that great care should be taken that this short delay is used beneficially, e.g. in-utero transfer, or steroid therapy. It is also important that this suppression does not result in an inappropriate delay where early delivery is indicated because of infection or fetal distress.

Steroids, tocolytics and antibiotics are potentially hazardous although all may benefit the fetus. The particular risks versus benefits of each form of therapy should be carefully considered for the particular presentation of each individual patient.

While all these agents given antenatally are of potential benefit to the fetus and neonate, prolongation of pregnancy for its own sake or for the sake of allowing time to administer such agents is no substitute for delivery of an infant in optimum condition.