Multifetal pregnancy: risks and methods of reduction

Multifetal pregnancy reduction offers an acceptable option to patients faced with the significant risk of long-term morbidity associated with multifetal gestation, especially gestation involving 4 or more fetuses. Until advances in reproductive technology eliminate the iatrogenic occurrence of multifetal gestation, and until progress in perinatal care decreases the threat of preterm delivery, multifetal pregnancy reduction offers hope for a good outcome in an otherwise dismal situation.

Management strategies for congenital infections

Information on congenital infection is continuously expanding. New diagnostic techniques are making significant contributions to the prenatal diagnosis of several fetal infections. In this review we highlight some of the most recent advances in the diagnosis and management of the most common fetal infections, those caused by cytomegalovirus, human immunodeficiency virus 1, Toxoplasma, varicella-zoster virus, and parvovirus B19.

Modified Stryker frame for intraoperative positioning of the patient with burns

Positioning large patients with burns for prone burn procedures can be very difficult, requiring operating room personnel to use a gang-lift technique. We have used the upper portion of a Stryker frame mounted to a standard operating room table base in more than 200 burn procedures in adults to move patients from the supine to the prone position, and back, without complication.

The use of the laryngeal mask airway to facilitate the insertion of a percutaneous tracheostomy

We report the use of the laryngeal mask airway to facilitate the insertion of a percutaneous tracheostomy (Ciaglia kit) in two patients. This method has not been reported previously. We believe that in selected patients the technique described increases the ease of placement of a percutaneous tracheostomy.

Confined placental mosaicism in CVS and pregnancy outcome

The perinatal outcome of 26 patients with confined placental mosaicism (CPM) detected in chorionic villus sampling (CVS) who wished to continue their pregnancies was compared with that of two controls per patient matched for age and parity (n = 52). There were no significant differences in birth weight or gestational age at delivery between patients with CPM and controls. There were no cases of intrauterine growth retardation (IUGR) in the CPM patients as compared with two (2/52, 3.8 per cent) in the control group (P > 0.05). There was no significant increase in fetal loss between the study group (1/26, 3.6 per cent) and the controls (1/52, 1.9 per cent) (P > 0.05).

Low concentrations of vaginal fetal fibronectin as a predictor of deliveries occurring after 41 weeks

OBJECTIVE

This study sought to determine whether low concentrations of fetal fibronectin in the cervical and vaginal secretions of patients at 39 weeks' gestation predicted pregnancies progressing beyond 41 weeks' gestation.

STUDY DESIGN

A retrospective cohort study was undertaken using cervical and vaginal samples collected from 75 consenting patients during the thirty-ninth week of gestation. Levels of fetal fibronectin were measured by immunoassay. Demographic, obstetric, neonatal, and laboratory data were analyzed by Fisher's exact test, Student t test or Wilcoxon's rank-sum test, multiple logistic regression, and receiver-operating characteristic curve analysis.

RESULTS

There was a 35.5-fold increase in vaginal fetal fibronectin concentrations among patients delivered at < 41 weeks compared with those delivered at > or = 41 weeks. The receiver-operating characteristic curve analysis indicated that the optimal fetal fibronectin predictor of prolonged pregnancies was a vaginal fetal fibronectin value < 60 ng/ml present between 39 weeks 0 days and 39 weeks 6 days' gestation (sensitivity 95.7%, 95% confidence interval 87.3% to 100.0%; specificity 44.2%, 95% confidence interval 30.7% to 57.7%; positive and negative predictive values 43.1% [95% confidence interval 29.5% to 56.7%] and 95.8% [95% confidence interval 87.8% to 100.0%], respectively). The relative risk for a prolonged pregnancy resulting from a vaginal fetal fibronectin value < 60 ng/ml was 10.4 (1.5 to 72.4). Among patients with a vaginal fetal fibronectin value > or = 60 ng/ml, 80.8% were delivered within 1 week and 92.3% within 10 days of sampling. In contrast, among patients with vaginal fetal fibronectin value < 60 ng/ml 63.3% remained undelivered after 1 week. After parity and cervical dilation were controlled for, multiple logistic regression demonstrated that a vaginal fetal fibronectin value < 60 ng/ml was a significant independent predictor of pregnancies delivered at > or = 41 weeks (adjusted odds ratio 12.8 [95% confidence interval 1.5 to 107.2]).

CONCLUSIONS

A vaginal fetal fibronectin value > or = 60 ng/ml at 39 weeks' gestation is predictive of delivery within 10 days, whereas values < 60 ng/ml identify 95% of pregnancies progressing past 41 weeks' gestation. This data may allow for the prediction of postdates pregnancies, thus facilitating appropriate obstetric interventions.

Efficacy of second-trimester selective termination for fetal abnormalities: international collaborative experience among the world's largest centers

OBJECTIVE

Our goal was to develop the most comprehensive database possible to counsel patients about selective termination for fetal abnormalities, because no one center has sufficient data to assess much more than crude loss rates.

STUDY DESIGN

A total of 183 completed cases of selective termination from 9 centers in 4 countries were combined (169 twins, 11 triplets, 3 quadruplets). Variables included indications, methods, (potassium chloride, exsanguination, air embolus), gestational age at procedure, pregnancies lost (< or = 24 weeks), gestational age at delivery, and neonatal outcome.

RESULTS

Indications for selective termination were 96 chromosomal, 76 structural, and 11 mendelian. Selective termination was technically successful in 100% of cases. In 23 of 183 (12.6%) miscarriage occurred before 24 weeks; 2 of 37 (5.4%) occurred when the procedure done at < or = 16 weeks and 21 of 146 (14.4%) when it was done thereafter. Air embolization had a higher loss rate: 10 of 24 (41.7%) compared with 13 of 156 (8.3%) by potassium chloride (chi 2 = 117, p < 0.0001). Three cases of selective termination performed in monochorionic pregnancies all resulted in pregnancy loss. Among 183 potentially viable deliveries, 7 occurred before 28 weeks, 19 at 29 to 32 weeks, 41 at 33 to 36 weeks, and 93 at > or = 37 weeks. Gestational age at delivery was not influenced by the technique used or the indication but was negatively correlated with gestational age at the time of selective termination. No coagulopathy or ischemic damage was observed in survivors. There was no maternal morbidity.

CONCLUSIONS

(1) Selective termination in experienced hands for a dizygotic abnormal twin is safe and effective when done with potassium chloride. A total of 83.8% of viable deliveries occurred after 33 weeks and only 4.3% at 25 to 28 weeks. (2) Gestational age at the procedure correlated positively with loss rate and inversely with gestational age at delivery; this emphasizes the need for early diagnosis in multifetal pregnancies. (3) Coagulopathy tests are probably unnecessary.

Unexpected neurological deficits following recovery from anaesthesia

Two cases of neurological dysfunction are presented. Neurological deficits after recovery from anaesthesia are unusual in young women perioperatively. In the first case, a 39-yr-old woman presented at 36-wk gestation with antepartum haemorrhage and in labour. Pregnancy had been complicated by pre-eclampsia and she underwent emergency Caesarean section under general anaesthesia without complication. The trachea was extubated when she was awake but almost immediately she became hypertensive, obtunded and reintubation was required. Her pupils became fixed and dilated but the Computerised Axial Tomogram (CT) was normal. A coagulopathy was evident. She made a full neurological recovery within 24 hr. On the same day, a previously healthy 41-yr-old woman who had undergone uneventful surgery for uterine prolapse 24 hr previously developed headache, nausea and over the next four hours signs of progressive brainstem ischaemia. The CT scan showed oedema of the mid- and hindbrain. Brainstem death was confirmed 12 hr later and the post-mortem revealed acute dissection of the vertebral artery secondary to cystic medial necrosis. Such dramatic neurological sequelae are rare but the importance of identifying "at risk" groups is underlined as is early recognition of neurological injury postoperatively.

Patient exposure to ionising radiation in the intensive care unit due to portable chest radiography

The chest X-ray is the most commonly performed radiological examination in the intensive care unit. We used TLDs to measure the radiation exposure in 30 ICU patients due to portable chest radiography. The mean number of CXR was 3 (range 1-11). The mean surface entry dose at the xiphisternum was 1.8 mGy (range 0.43-5.14 mGy) per patient and 0.63 mGy per CXR. Very small amounts of radiation were detected at the symphysis pubis and in more than half of the patients no radiation was detected at this site. These values are well above accepted norms. Patient exposure may be reduced by ordering fewer X-rays or by changing to a faster screen-film combination.

Transabdominal versus transcervical and transvaginal multifetal pregnancy reduction: international collaborative experience of more than one thousand cases

OBJECTIVES

Two major approaches for multifetal pregnancy reduction have been developed over the past several years: transabdominal potassium chloride by injection and pelvic procedures by either transcervical aspiration or transvaginal potassium chloride injection or by an automated spring-loaded puncture device. The purpose of this study was to create the largest database from among the world's largest centers to assess possible differences in efficacy and complication rates by transabdominal or transcervical or multifetal pregnancy reduction.

STUDY DESIGN

Data on over 1000 completed pregnancies that underwent multifetal pregnancy reduction by both methods from major centers with among the highest worldwide experience were combined. Transabdominal cases were divided temporally (1986 through 1991 and 1991 through 1993).

RESULTS

Transabdominal multifetal pregnancy reduction was successfully performed on 846 patients and transcervical or transvaginal on 238 patients. Transcervical or transvaginal reduction is performed earlier and starts and finishes with fewer embryos. In 12.6% of cases transcervical or transvaginal reduction left a singleton as opposed to 4.4% for transabdominal reduction. Pregnancy losses (up to 24 weeks) were observed in 13.1% of transcervical or transvaginal cases and in 16.2% of transabdominal cases early in the series and 8.8% of late transabdominal cases. Transcervical or transvaginal reduction may be safer very early in gestation and transabdominal safer later in the first trimester. Premature deliveries were comparable, with only about 5% delivered between 25 and 28 weeks. The smaller starting numbers for transcervical and transvaginal reduction may explain a slightly higher term delivery rate. The transabdominal route tends to reduce the fundal embryos and the transcervical and transvaginal the lower ones. The significance of this is not clear.

CONCLUSIONS

(1) Multifetal pregnancy reduction by either method is a relatively safe and efficient method for improving outcome in multifetal pregnancies. (2) More than 84% are delivered at > 33 weeks. (3) The experience and preference of the operator are probably the key determinants for an individual patient. (4) An inverse relationship of starting and finishing number to loss rates and gestational age at delivery suggests that there still is a cost of iatrogenic multifetal pregnancies, even if multifetal pregnancy reduction can be successfully performed.

The Female Athlete Triad

In brief Though appropriate exercise has many health benefits for women, there is a point of diminishing returns. Young female athletes driven to excel in their chosen sports are at risk of developing a potentially fatal triad of disorders. By recognizing the connection between disordered eating, amenorrhea, and osteoporosis, physicians can help athletic young women stay active while avoiding significant morbidity.

The effect of fetal gender on the prediction of Down syndrome by means of maternal serum alpha-fetoprotein and ultrasonographic parameters

OBJECTIVE

Our investigation was designed to use maternal serum alpha-fetoprotein and individual or combinations of ultrasonographic parameters to examine the influence of fetal gender on the prediction of Down syndrome.

STUDY DESIGN

A cohort study of 5114 patients who underwent karyotype analysis between 13 and 22 weeks' gestation was undertaken. Maternal demographic variables, anthropometric indices, and maternal serum alpha-fetoprotein values were assessed. Fetal parameters recorded included gender, biparietal diameter, head circumference, femoral and humeral length, transverse cerebellar diameter, and nuchal fold thickness. The effect of fetal gender on maternal serum alpha-fetoprotein values and ultrasonographic parameters was assessed. Gender-specific differences between fetuses with Down syndrome and euploid fetuses were identified, and the optimal cutoff values of individual and combinations of biometric parameters were determined by receiver operating characteristic curve analysis.

RESULTS

A total of 42 fetuses with Down syndrome were identified. Female fetuses with Down syndrome had significantly lower maternal serum alpha-fetoprotein values than their male counterparts, and maternal serum alpha-fetoprotein screening paradigms resulted in the disproportionate identification of affected female fetuses. A nuchal fold thickness > or = 5 mm was the single best ultrasonographic predictor of Down syndrome independent of fetal gender. Affected male fetuses had significantly smaller mean femoral and humeral lengths than euploid fetuses after adjustment for biparietal diameter, but only the humeral length proved a clinically useful predictor of Down syndrome. Pearson's correlation coefficient confirmed that nuchal fold thickness and humeral length were independent of each other and of maternal age and maternal serum alpha-fetoprotein levels. The optimal ultrasonographic predictor of Down syndrome was the presence of either a nuchal fold thickness > or = 6 mm or a humeral length > 3.5 to 3.7 mm below the expected value. This combination of ultrasonographic findings identified 41.7% of female and 66.7% of male fetuses with Down syndrome.

CONCLUSIONS

Fetal gender affects the prediction of Down syndrome by both maternal serum alpha-fetoprotein and ultrasonographic parameters. Moreover, the ultrasonographic detection of Down syndrome in fetuses is greatly improved by a combination of gender-specific biometric parameters.

Maternal serum alpha-fetoprotein and coagulation profiles after multifetal pregnancy reduction

OBJECTIVE

Our purpose was to determine the effect of first-trimester multifetal pregnancy reduction on maternal serum alpha-fetoprotein and coagulation profiles in the second trimester.

METHODS

Maternal serum alpha-fetoprotein was determined in 57 patients 1.5 to 10 weeks after multifetal pregnancy reduction, and coagulation profile was determined in 17 patients 2 to 5 weeks after the procedure. All but one had living twins at the time of testing.

RESULTS

All patients had elevated maternal serum alpha-fetoprotein levels (mean 11.6 +/- 7.6 multiples of the median) compared with normal twin values (< 3.5 multiples of the median). There was a positive correlation between maternal serum alpha-fetoprotein level and the number of dead fetuses and a negative correlation between maternal serum alpha-fetoprotein level and the number of weeks elapsed since multifetal pregnancy reduction. Amniotic fluid alpha-fetoprotein was measured in 10 patients and was normal. Fibrin split products were positive in 1 of 17 patients, intermediate in two of 17 and negative in 14 of 17. Prothrombin time, partial thromboplastin time, fibrinogen, and platelet counts remained normal. None of the patients had clinical evidence of disseminated intravascular coagulation, and treatment for that condition was not given.

CONCLUSIONS

Maternal serum alpha-fetoprotein in the second trimester is always elevated after multifetal pregnancy reduction and is not necessarily indicative of fetal defects. This elevation is probably caused by release of tissue or serum from the dead fetus(es). Amniocentesis is not indicated in these cases, but ultrasonography to evaluate fetal anatomy should be considered because maternal serum alpha-fetoprotein cannot be used in these patients to screen for fetal defects. Some patients can have laboratory evidence of disseminated intravascular coagulation after multifetal pregnancy reduction, but it may resolve spontaneously.

The risk of second-trimester amniocentesis in twin gestations: a case-control study

OBJECTIVE

Pregnancy outcomes in patients with twin pregnancy undergoing second-trimester amniocentesis for fetal karyotype assessment were compared in a case-control study with twin pregnancies undergoing routine ultrasonographic studies at similar gestational ages.

STUDY DESIGN

All spontaneous and induced twin gestations that underwent ultrasonographic examination between 14 and 20 weeks were compiled for the period January 1987 through January 1992. Patients having undergone multifetal reduction or chorionic villous sampling and those with fetal anatomic or chromosomal anomalies, discordant growth (> 20%), death, or a monoamniotic sac detected at ultrasonography were excluded.

RESULTS

The mean (+/- SD) maternal age was significantly higher among the 101 cases than among the 108 controls (35.2 +/- 3.5 vs 30.4 +/- 5.3 years, respectively; p < 0.01). No differences were noted in gravidity, parity, number of prior spontaneous losses, or gestational age at ultrasonography between the two groups. The fetal loss rate was similar among cases and controls (seven of 202 [3.5%] vs seven of 216 [3.2%], relative risk 1.07, 95% confidence intervals 0.3 to 3.5). No losses occurred within 3 weeks of the procedure. Gestational age at delivery, birth weight, mean Apgar scores at 1 and 5 minutes, and length of neonatal stay were not significantly different between cases and controls.

CONCLUSIONS

Second-trimester amniocentesis in twin pregnancies is apparently not associated with excess pregnancy loss.

Prenatal diagnosis and significance of fetal infections

Viruses like rubella, cytomegalovirus, varicella-zoster virus and parasites like Toxoplasma gondii can be transmitted from a pregnant woman to her fetus and can affect fetal development. Several factors determine the likelihood of fetal infection and the risk of consequences for the fetus, such as the timing of transmission during gestation or the immunologic status of the mother. No single diagnostic modality can be applied to all infections. Knowledge of the diagnostic methods available is essential for accurate counseling and treatment of affected pregnant women.

First-trimester transabdominal multifetal pregnancy reduction: a report of two hundred completed cases

OBJECTIVE

Multifetal pregnancy reduction has been proposed as a way to reduce the risk of preterm delivery in women who conceive three or more fetuses. This communication presents the outcome of 200 consecutive multifetal pregnancies in which reduction to a smaller number of fetuses was accomplished.

STUDY DESIGN

All of the procedures were performed in the first trimester by the transabdominal injection of potassium chloride into the thoraces of those fetuses that underwent feticide. All of the pregnancies have been completed and outcome data have been obtained in every case.

RESULTS

At the time of the procedure 88 women had triplets, 89 had quadruplets, 16 had quintuplets, and 7 had from 6 to 9 fetuses. These pregnancies were reduced to 189 sets of twins, 5 sets of triplets, and 6 singletons. Reductions to triplets were done at the patient's request, and reductions to singletons were only done for medical indications. There were no cases of chorioamnionitis or other maternal complications attributable to the procedure. A total of 181 women were delivered of one or more live infants after 24 weeks' gestation, and 19 (9.5%) lost all of their fetuses before that time. The mean gestational age for all women delivered after 24 weeks was 35.7 weeks. The mean gestational age at delivery varied inversely with the initial number of fetuses, from 36.1 weeks for women who presented with triplets to 33.8 weeks for those who had 6 or more fetuses, and this trend was statistically significant. Sixteen of the 19 complete pregnancy losses occurred > 4 weeks after the reduction procedure had been performed. The loss rates were 7.9% for those who presented with 3 or 4 fetuses, 12.5% for those with 5, and 42.9% for those with > or = 6. This trend was statistically significant. Two neonates died in the first week of life and one died at 10 months of age as a consequence of the sequelae of severe prematurity. Only two surviving infants have shown evidence of chronic morbidity related to early delivery, and all of the others are developing normally.

CONCLUSION

The incidence of intrauterine growth retardation was not increased over that anticipated in a population of twins.

Efficacy of transabdominal multifetal pregnancy reduction: collaborative experience among the world's largest centers

OBJECTIVE

To evaluate the safety and efficacy of transabdominal multifetal pregnancy reduction (MFPR) in the management of iatrogenic and spontaneous multifetal pregnancies.

METHODS

Data were combined from 463 completed pregnancies that underwent MFPR at major worldwide centers.

RESULTS

Multifetal pregnancy reduction was performed with a 100% technical success rate (there were no failed procedures); 83.8% had delivery of potentially viable fetuses (defined as 24 weeks' gestation or later), and 83.5% of these viable pregnancies delivered at 33 weeks or later. The risk of fetal loss was 3.9% at 2 weeks or less post-procedure, 4.6% at 4 weeks or less, and 16.2% at less than 24 weeks of gestation. Gestational age at delivery varied principally with the number of fetuses remaining, with 7.1% delivering prematurely at less than 28 weeks, and 9.4% at 29-32 weeks. The incidence of obstetric and medical complications appeared to be unaffected, and there was no increase in congenital malformations.

CONCLUSIONS

Multifetal pregnancy reduction is an efficient and safe way of improving outcome in multifetal pregnancies, unambiguously for quadruplets or more, and arguably for triplets. However, particularly at higher starting numbers, there are still suboptimal outcomes. We cannot answer the question of whether MFPR should be offered to women with triplets or twins. The only major risk appears to be fetal loss per se, and because the procedure itself does not damage the survivors, parental autonomy should be given a higher priority in the decision process than previously. However, to obviate the need for this procedure, infertility specialists must continue to be vigilant in the use of fertility drugs.

Perinatal infections

Information concerning the most recently discovered infections with perinatal implications is constantly expanding. Hepatitis C virus is responsible for the majority of cases of sporadic and transfusion-related non-A, non-B hepatitis. Its prevalence in the general obstetric population is approximately 2%, but it is much higher in intravenous drug users and recipients of blood transfusions. The risk of vertical transmission is probably small (approximately 4.5%), but mothers coinfected with hepatitis C virus and human immunodeficiency virus type 1 are at higher risk of transmitting infection, possibly as a result of higher levels of viremia. Parvovirus B19 infection can jeopardize the fetus in approximately 9% of cases, leading to profound anemia, followed by hydrops and death. B19 has not been proven to be teratogenic, but survivors have a greater risk of in utero growth retardation. Cytomegalovirus remains the most common cause of congenital infections, and the fetal effects of primary maternal infection during gestation can be devastating. Recurrent infections carry a much lower risk of vertical transmission. Prenatal diagnosis is feasible and reliable. The factors affecting the vertical transmission of human immunodeficiency virus type 1 have been further delineated, and new avenues of research have been opened.

An autopsy case review of 142 nonpenetrating (blunt) injuries of the aorta

This study retrospectively reviewed 142 fatal cases of aortic laceration. Data were collected from the autopsy reports (including toxicology results) and included the circumstances of the injury. In the case of automobile crashes this included the direction of impact, time of day, and vehicular damage. Seventy percent of the victims were men with a mean age of 37.5 years; 30% were women with a mean age of 46 years. Thirty-five percent of the 142 victims had elevated blood alcohol levels. Fifty-four percent of the lacerations were located at the classic site (the isthmus). The majority of the aortic lacerations (102) were sustained in automobile crashes. Of these, 42% were broadside collisions and 58% were head-on collisions. Seventy-three percent and 67% of the victims in broadside and head-on collisions, respectively, had aortic lacerations at the classic site. The results suggest that the pathogenesis of aortic rupture involves a lateral oblique compression impact to the chest, which causes thoracic mediastinal structures to shift and deflect the aortic arch, resulting in severe shearing and stretching at the isthmus. The use of seat belts and air bags may reduce the number of aortic injuries.

Morbidity of failed labor in patients with prior cesarean section

OBJECTIVE

The aim of our study was to determine whether the reported increased morbidity associated with failed attempted vaginal birth after cesarean section is attributable to the presence of a uterine scar alone or to labor preceding a cesarean section.

STUDY DESIGN

Primiparous women (N = 237) who underwent repeat cesarean section after a failed trial of vaginal birth after cesarean section were retrospectively compared with 1582 nulliparous women who underwent a primary cesarean section after a failed trial of labor.

RESULTS

There were no significant differences in maternal or neonatal morbidity between the two groups except for an increase in the prevalence of thin meconium in patients undergoing primary cesarean section.

CONCLUSION

Our results suggest that the presence of a previous cesarean section scar does not increase the overall baseline morbidity associated with cesarean section after labor.

Antenatal treatment of alloimmune thrombocytopenia

OBJECTIVE

Neonatal alloimmune thrombocytopenia is caused by platelet antigen incompatibility between the mother and fetus. Affected fetuses may have severe thrombocytopenia leading to intracranial hemorrhage before or at birth. We sought to treat this condition in utero to prevent these hemorrhages.

METHODS

Eighteen women who had previously delivered infants with severe alloimmune thrombocytopenia were treated with weekly infusions of intravenous gamma globulin from the diagnosis of fetal thrombocytopenia until birth; nine were also treated with corticosteroids.

RESULTS

There were no intracranial hemorrhages in the treated fetuses, compared with ten cases among the 21 untreated siblings (48%). Only three treated fetuses, compared with 16 of 20 untreated siblings, had platelet counts of less than 30,000/microL, with no bleeding complications.

CONCLUSION

Antenatal treatment of alloimmune thrombocytopenia with weekly gamma globulin effectively improves the fetal platelet count and prevents intracranial hemorrhage.

[Infectious fetal diseases. Prevention, prenatal diagnosis, practical measures]

Many congenital infections can produce foetal diseases and are sometimes responsible for major disablements. The most frequent infectious foetal diseases are toxoplasmosis, rubella and chickenpox. Diseases caused by parvovirus or cytomegalovirus are exceptional. Foetal blood sampling has considerably simplified the prenatal diagnosis and made it accessible to more medical centres; it has also widened the therapeutic possibilities and above all, it has considerably reduced the number of therapeutic abortions. It may well be that the development of molecular biology, which has the great advantage of permitting an earlier diagnosis, will in the near future make it possible not only to detect numerous monogenic diseases before birth, but also to diagnose some foetal infections. We might then hope that a much earlier treatment in utero will also be more effective.