Women's Experiences of Mechanical Balloon Catheter Induction With Self-Traction.

OBJECTIVE: To explore women's experiences of mechanical labor induction using a balloon catheter with self-traction. DESIGN: Descriptive qualitative. SETTING: Birth unit of an urban hospital in Quebec, Canada. PARTICIPANTS: Fourteen women who experienced labor induction with a balloon catheter using self-traction. METHODS: We conducted individual structured interviews between May 2022 and January 2023 to collect data that we subsequently analyzed using the manifest content analysis approach of Graneheim et al. We adhered to the Consolidated Criteria for Reporting Qualitative Research (COREQ). RESULTS: We identified five categories: Expectations, Pain or Comfort Experienced, Emotions Felt, Support From Nursing Staff, and Appreciation of the Procedure. The participants anticipated rapid, effective induction, expressed concerns about potential discomfort, and appreciated control of their experiences. We found a generally positive trend in terms of appreciation for all categories. CONCLUSION: The positive experiences of participants underline the promising potential of the balloon catheter method of labor induction with self-traction. Given the continuing growth in labor induction rates, it becomes necessary to continue efforts to offer services specifically geared to women's needs. Offering an additional option such as self-traction is a step in this direction.

Self-Traction During Mechanical Cervical Dilatation, Acceptability, Feasibility and Satisfaction of its Application: A Pilot Study.

This study aims to measure acceptability, feasibility, and satisfaction with self-traction during mechanical cervical dilatation to induce labour and to explore its effects on pain and the process of labour and delivery. 60 parturients were randomly assigned to self-traction or regular traction. Participants completed questionnaires about sociodemographic characteristics, acceptability, and satisfaction. Self-traction participants reported significantly higher acceptability (P = 0.026), and adequacy (P = 0.018). They also reported satisfaction with the procedure. A group comparison regarding feasibility, pain, and the process of labour and delivery showed no significant difference. Self-traction is an acceptable and feasible intervention for full-term parturients.

Predictive score for early preterm birth in decisions about emergency cervical cerclage in singleton pregnancies.

OBJECTIVE: To develop a simple score for assessing the risk of early preterm delivery before 32 weeks in women with singleton pregnancies receiving emergency cervical cerclage. DESIGN: Retrospective study. SETTING: French tertiary care center from 1994 to 2006. POPULATION: A total of 134 pregnant women underwent emergency cervical cerclage procedure at 15-26 weeks. The analysis concerned 85 singleton pregnancies after exclusion of women with a dilated cervix without visible membranes, or presenting for revision of failed prophylactic cerclage, or who had either preterm premature rupture of membranes or clinical signs of chorioamnionitis. METHODS: Multivariate logistic regression methods with rounded coefficients were used to develop a score to predict early preterm delivery before 32 weeks. MAIN OUTCOME MEASURES: Early preterm delivery before 32 weeks. RESULTS: The score, ranging from 0 to 15 points, was based on the following four criteria independently associated with early preterm delivery: obstetric history; cervical dilatation; membranes bulging into the vagina; and infection. Each score value was associated with a predicted probability of early preterm birth. CONCLUSIONS: The score and its associated early preterm probabilities may be a valuable tool to help physicians in advising women about the need for emergency cerclage.

Accuracy of three-dimensional ultrasonography in differential diagnosis of septate and bicornuate uterus compared with office hysteroscopy and pelvic magnetic resonance imaging.

STUDY OBJECTIVE: To estimate the accuracy of 3-dimensional (3-D) ultrasonography in the differential diagnosis of septate and bicornuate uterus compared with office hysteroscopy and pelvic magnetic resonance imaging (MRI). DESIGN: Prospective cohort study (Canadian Task Force Classification II-2). SETTING: University hospital. PATIENTS: Thirty-one patients referred with a suspected diagnosis of septate (n = 20) or bicornuate (n = 11) uterus. INTERVENTIONS: All patients underwent 3-D ultrasonography displaying the rebuilt coronal view of the uterus, office hysteroscopy, and pelvic MRI. Operative hysteroscopic assessment and treatment was performed in case of sonographically diagnosed septate uterus. Bicornuate uterus was confirmed by laparoscopy. MAIN OUTCOMES MEASURES: Concordance between suspected diagnosis with 3-D ultrasonography, hysteroscopy, and pelvic MRI and final diagnosis. RESULTS: A septate uterus was diagnosed with 3-D ultrasonography in 29 patients and bicornuate uterus in 2 patients. Hysteroscopic transcervical section of the uterine septum was achieved in the 29 patients. Bicornuate uterus was laparoscopically confirmed in the 2 patients. Concordance between ultrasonography and operative hysteroscopy or laparoscopy was verified in all 31 cases. Twenty-five uterine septa and 5 bicornuate uteri were diagnosed by hysteroscopy (3 false-positive diagnoses of bicornuate uterus, 1 unfeasible hysteroscopy). Hysteroscopic diagnosis was correct in 27/30 patients. Twenty-four septate uteri and 7 bicornuate uteri were diagnosed by MRI (5 false-positive diagnoses of bicornuate uterus). Two complete septate uteri diagnosed by MRI were finally confirmed as incomplete septate uteri after 3-D ultrasonography and operative hysteroscopy. MRI diagnosis was correct in 24/31 patients. CONCLUSION: Transvaginal 3-D ultrasonography appears to be extremely accurate for the diagnosis and classification of congenital uterine anomalies, more than office hysteroscopy and MRI. It may conveniently become the only mandatory step in the assessment of the uterine cavity in patients with a suspected septate or bicornuate uterus.

Treatment of twenty-two patients with complete uterine and vaginal septum.

STUDY OBJECTIVE: To assess the fertility and obstetric outcome after surgical treatment of complete uterine and vaginal septum. DESIGN: Retrospective study (Canadian Task Force Classification II-2). SETTING: Teaching hospital in France. PATIENTS: Twenty-two women who have experienced infertility, pregnancy losses, dyspareunia, or dysmenorrhea. INTERVENTION: Hysteroscopic section of complete uterine septum and resection of longitudinal vaginal septum. MEASUREMENTS AND MAIN RESULTS: Improvement of dyspareunia or dysmenorrhea and obstetric outcome, focusing on the miscarriage rate, obstetric complications, and the gestational age at delivery were assessed. Overall, 20 women had conceived a total of 37 pregnancies, with 10 and 8 deliveries before and after metroplasty, respectively. Median gestational age at delivery was not significantly different in both groups (36.5 [33-39.5] vs 38.0 weeks' gestation [35-40], respectively). Preterm delivery occurred in 4 cases (25%) before the surgery and in 3 cases (14%) after (p = .44). The live birth rate was also not significantly different before and after surgery (62.5% and 38%, respectively) (p = .19). There was a decrease of caesarean section and significantly fewer breech deliveries after metroplasty (p = .01). A decrease in the prevalence of dyspareunia or dysmenorrhea was observed after metroplasty in the 19 patients originally displaying these symptoms. No perioperative complications were observed in this series. CONCLUSION: Resection of vaginal septum and hysteroscopic metroplasty for complete uterine septum with resection of the cervical septum is a safe procedure that may improve dyspareunia and dysmenorrhea when present. Reproductive and obstetric outcomes after this procedure do not appear to be compromised, even though a relatively high miscarriage rate remains after metroplasty, questioning its systematic practice in symptom-free women without any previous obstetric history.

3D ultrasound to assess the position of tubal sterilization microinserts.

BACKGROUND: The aim of this study was to assess the diagnostic accuracy of three-dimensional ultrasound (3D-US) for determining the position of Essure microinserts and the success of sterilization by the Essure method. METHODS: This retrospective observational study examined the case records of 311 women who underwent hysteroscopic sterilization from October 2002 through October 2008. Imaging with 3D-US or pelvic X-radiography or both was performed 3 months after the procedure to verify device position. Hysterosalpingography (HSG) was performed when a bilateral procedure was not completed because of a history of salpingectomy or blocked tube, when doubt persisted after 3D-US or pelvic radiography, or for comparative purposes in a prospective study. The positions seen on 3D-US were classified in four categories according to a specific scale we devised. RESULTS: The insertion procedure was completed in 94.2% patients. Only 90.5% underwent imaging verification of the device 3 months afterwards. In all, 227 3D-US, 175 pelvic radiography and 64 HSG imaging procedures were performed. Visualization of the device was possible in 99.6% of the 3D-US images. According to our classification, 3D-US was appropriate for assessing device position for 195 (85.9%) patients. The need for HSG confirmation was significantly lower with 3D-US than radiographic imaging (14.1 versus 26.8%, P = 0.001). 3D-US examinations, compared with the results of HSG as the reference test, had a sensitivity of 100% and a specificity of 76.6%. Neither pregnancy nor early expulsion occurred when 3D-US found that the devices were correctly placed. CONCLUSIONS: 3D-US is a simple technique for assessing the position of Essure(®) microinserts, even after concomitant endometrial surgery. The 3D-US classification presented here appears to make it possible to use HSG for back-up confirmation only when the microinsert is found in a very distal position on 3D-US and thus to protect the majority of women from the negative effects of pelvic radiography and HSG.

Surgical management of infertility due to polycystic ovarian syndrome after failure of medical management.

OBJECTIVES: To evaluate surgical management and fertility and pregnancy outcome in women with polycystic ovarian syndrome (PCOS). STUDY DESIGN: Retrospective file review and follow-up of 74 consecutive women with PCOS resistant to citrate clomiphene (CC) who underwent ovarian drilling by fertiloscopy with bipolar energy, together with hysteroscopic surgery when indicated (Canadian TASK FORCE II-2). RESULTS: Of 77 files, only 3 women were lost to follow-up. Mean age was 30.2 years (SD 5.3) [29.0-31.4 CI 95%], and mean BMI 25.6kg/m(2) (SD 6.2) [24.2-27.0 CI 95%]. Pregnancy occurred after drilling in 47 cases (63%), spontaneously in 20 (27%), after ovarian stimulation in 5 (6.7%) and after in vitro fertilization in 22 (29.7%). Laparoscopic conversion was required in 5 cases (6.7%), due to failure to visualize the adnexa (n=3), or pelvic adhesions (n=1), or uterine hemorrhage (n=1). Hysteroscopy detected and simultaneously treated a uterine anomaly in 18 of 74 patients: uterine septum (n=10, 13%), T-shaped uterine cavity (n=3, 4%), endometrial polyp (n=2, 2.7%), endometrial hypertrophy (n=2, 2.7%), and synechiae (n=1, 1.3%). The mean overall delay to pregnancy was 11.1 months (SD 8.5) [8.7-13.5 CI 95%] and to spontaneous pregnancy, 7 months (SD 7.6) [3.7-10.3 CI 95%]. The mean follow-up was 23.4 months (SD 16.5) [18.1-28.7 CI 95%]. After multivariate analysis, the likelihood of pregnancy was significantly associated with previous ovarian stimulation by FSH (OR=2.28, 95% CI=1.08-4.83) and initial FSH level (OR=0.52, 95% CI=0.29-0.93). CONCLUSION: Ovarian drilling by hydrolaparoscopy is an effective treatment for CC-resistant PCOS. The high rate of associated uterine anomalies justifies simultaneous hysteroscopic surgery.

Transvaginal cervicoisthmic cerclage using a polypropylene sling: pregnancy outcome.

AIM: To report pregnancy outcome following prophylactic transvaginal cervicoisthmic cerclage using a polypropylene sling in a population of high-risk pregnant women. MATERIALS AND METHODS: A retrospective study with a continuous series of 57 women presenting with prior failure of McDonald cerclage (n = 47) and/or absent portio-vaginalis of the cervix (n = 10). RESULTS: Cervicoisthmic cerclage was performed between 12 and 16 weeks of gestation (median 14 weeks' gestation). No intraoperative complication occurred. Preterm labor treated with parenteral tocolysis occurred in 14 women (24%). Cesarean delivery was systematically performed. Median gestational age at delivery was 37.2 weeks' gestation (interquartile range: 36.5-38.0). Overall neonatal survival rate was 94%. CONCLUSION: Transvaginal cervicoisthmic cerclage using a polypropylene sling may be considered as an effective alternative to the transabdominal cervicoisthmic cerclage in women presenting with previous cerclage failure.

Ovarian drilling for surgical treatment of polycystic ovarian syndrome: a comprehensive review.

This systematic literature review is intended to clarify and evaluate the results obtained by ovarian drilling as surgical treatment for polycystic ovarian syndrome (PCOS). Four databases were consulted (Medline at the National Library of Medicine, USA; Cochrane Library, UK; National Guideline Clearinghouse, USA; and the Health Technology Assessment Database, Sweden) and searched for 'polycystic ovary syndrome' plus 'drilling' in the title or abstract. The assessment criteria used to define the efficacy of the procedure were the rates of ovulation, clinical pregnancy and early miscarriage. Alternatives to surgical ovarian drilling were evaluated. This search produced 147 references, 81 of which met the selection criteria. This review of infertility management in women with PCOS indicates that ovarian drilling is a second-line treatment when treatment with clomiphene citrate fails to lead to conception. The benefits of ovarian drilling are that it does not induce either hyperstimulation syndrome or multiple pregnancies. It is concluded that ovarian drilling is an option in the management of female infertility associated with PCOS, especially as a second-line treatment after the failure of clomiphene citrate treatment.

Surgical approach to and reproductive outcome after surgical correction of a T-shaped uterus.

BACKGROUND: The aim of this study was to describe the surgical approach to, and evaluate the reproductive outcome of, a T-shaped uterus. METHODS: The study included 97 women who were eligible for hysteroscopic surgery, by either monopolar or bipolar electrosurgical instruments. All had diagnostic hysteroscopy 2 months afterwards to assess the success of the procedure and determine whether any synechiae were present. RESULTS: Forty-eight women (49.5%) became pregnant after metroplasty. The overall live birth rate per pregnancy before surgery was 0%; for these patients, it increased to 73%, and their miscarriage rate fell from 78 to 27% (P < 0.05). For all 57 pregnancies in 48 women, the ectopic pregnancy rate was 9% (n = 5), the miscarriage rate 28% (n = 16), the preterm delivery rate 14% (n = 8), the term delivery rate 49% (n = 28) and the live birth rate was 63% (n = 36). CONCLUSIONS: Hysteroscopic metroplasty improves the live birth rate for women with a T-shaped uterus and a history of primary infertility, recurrent abortion or preterm delivery, although it is not a treatment of infertility.

Tubal anastomosis after tubal sterilization: a review.

PURPOSE: To evaluate various techniques for restoring tubal patency after sterilisation. METHODS: A search strategy was designed, and for each subject either thesaurus terms (MeSH descriptors) or terms from the title or summary were used. RESULTS: Mean length of hospital stay following laparoscopy seems to be shorter in comparison with laparotomy (3.3 vs. 6.1 days, P < 0.05). Rate of conversion to laparotomy is 5%. Pregnancy rates observed are between 54 and 88% for laparotomy and 31-85% for laparoscopy. Mean time to conception was between 2 and 9.6 months. Most pregnancies occurred in the 2 years following restoration of tubal patency (cumulative conception rate 80% at 12 months). Young age (<35 years), type of ligature (rings), how recently the ligature was done (<8 years), the anastomosis site (in the middle of the tube) and a good length of remaining tube (>7 cm) are the factors that govern whether there can be good restoration of tubal patency. Ectopic pregnancy rates observed are between 1.7 and 12% for laparotomy and 0-7% for laparoscopy. There are no randomised or quasi-randomised studies comparing tubal anastomosis and in vitro fertilization. CONCLUSIONS: There are few good-quality controlled studies in this area. Results of restoration of tubal patency seem to be comparable, regardless of the route of approach (laparotomy or laparoscopy).

Ultrasound cervical length measurement for prediction of delivery before 32 weeks in women with emergency cerclage for cervical insufficiency.

OBJECTIVE: To assess the accuracy of ultrasound cervical length for predicting delivery before 32 weeks among women with a threatened second trimester fetal loss treated by emergency cervical cerclage, and to compare it with prediction based on clinically-assessed cervical dilation. METHODS: Retrospective study (1997-2006) of 70 women with singleton pregnancies who underwent emergency cervical cerclage and ultrasound cervical length measurement between 15 and 26 weeks. The associations between cervical length and delivery before 32 weeks were studied with univariate and multivariate regression. ROC curves were used to determine the most discriminating cut-off value. RESULTS: Although ultrasound cervical length measurement was significantly associated with early preterm delivery, its predictive accuracy was moderate with an area under the ROC curve (AUC) of 0.68 (95% CI, 0.54-0.82), which was similar (P=0.43) to the AUC of cervical dilation of 0.73 (95% CI, 0.61-0.85). The best cut-off value was 7 mm, corresponding to a doubled risk of delivery before 32 weeks. Its sensitivity was 52%, specificity 82%, PPV 62%, and NPV 76%. It was no more informative than cervical dilation of 3 cm. CONCLUSION: Ultrasound cervical length measurement does not predict early preterm birth better than clinically-assessed cervical dilation in women with an emergency cerclage.

Assessment of three-dimensional ultrasound examination classification to check the position of the tubal sterilization microinsert.

OBJECTIVE: To assess the accuracy of three-dimensional (3D) ultrasound to determine the position of Essure microinserts. DESIGN: Prospective observational study. SETTING: Gynecology department in a teaching hospital. PATIENT(S): Forty women who underwent hysteroscopic sterilization from March through October 2008. INTERVENTION(S): Both 3D ultrasound and hysterosalpingography (HSG) were performed 3 months after the procedure to verify device position. Positions seen on 3D ultrasound were classified in four categories: a perfect position (1 + 2 + 3), a proximal position (1 + 2), a distal position (2 + 3), and a very distal position (3-only). MAIN OUTCOME AND MEASURE(S): Microinsert position on 3D ultrasound and correlation with HSG. RESULT(S): Overall, 93% of the devices for 40 patients were found to have been placed successfully. The final sample comprised 64 Essure devices. HSG showed tubal patency for only three devices, all classified as 3-only. No tubal permeability was noted for the other 61 positions. This 3-only location on 3D ultrasound was statistically associated with a failure of sterilization in comparison with the other locations (3/16 [18%] vs. 0/48 [0%]). CONCLUSION(S): 3D ultrasound is a simple and reproducible technique to assess the position of the Essure microinsert and appears to protect most patients from the negative aspects of pelvic radiography and of HSG. Using the 3D ultrasound classification presented in this study appears to make it possible to use HSG for backup confirmation only when Essure is found to be in the 3-only position on 3D ultrasound.

Trans-vaginal cystocele repair using a tension-free polypropylene mesh: more than 5 years of follow-up.

OBJECTIVES: Prospective randomized controlled trials, with 2 years' follow-up, seem to lean in favour of anterior repair using synthetic mesh. The goal of this study was to report on long-term (>5 years) follow-up. STUDY DESIGN: Polypropylene mesh was inserted in 63 women (in 1999-2001) from the retropubic space to under the bladder using a tension-free technique. RESULTS: At 79 months' follow-up, 45 women were anatomically cured (76%). Four (7%) were lost to follow-up and 14 (24%) presented with stage 2 or 3 cystocele recurrences. None of them required surgery for cystocele recurrence. Vaginal extrusion was reported in 10 (16%) patients (in four cases after 4 years of follow-up) and all required partial surgical removal of the mesh (n=10, 16%). CONCLUSION: Cystocele repair using tension-free polypropylene mesh is associated with a low long-term rate of repeat surgery for cystocele recurrence.

Vaginal myomectomy: literature review.

The objective of this literature review was to evaluate the results obtained at vaginal myomectomy. The databases consulted were Medline, Cochrane Library, National Guideline Clearinghouse, and Health Technology Assessment Database. Keywords used for research were colpotomy, myomectomy, and vaginal myomectomy, and then abdominal myomectomy, laparoscopic-assisted vaginal myomectomy, and laparoscopic myomectomy. Eight case series and 2 case reports were analyzed, and included 372 patients. Reported rates of conversion to laparotomy during the operation ranged from 0% to 17.6%. The most frequently described risk factors for conversion to laparotomy were location of the myoma in the fundus and a large volume of myoma to be extracted, although no maximum threshold size can be defined. Performing laparoscopy first does not seem to limit the risk. Reported rates of transfusion during the operation ranged from 0% to 40%. Several cases of pelvic abscess have been described, with reported frequency of 2.2% to 5.7%. Authors mentioned the role of the vaginal drain that is inserted at the end of the procedure. No specific studies have been performed on long-term effectiveness, postoperative adhesions, integrity of the scar, or subsequent fertility. There are no good controlled studies of this technique. Feasibility seems to be acceptable, although the risk of pelvic infection in the postoperative period may be increased. Long-term effectiveness and safety were not assessed. A vaginal approach may be considered an alternative to laparotomy or laparoscopy in surgery to treat accessible myomas, and seems to be the simplest method.

Fertility outcome following transvaginal cervicoisthmic cerclage using a polypropylene sling.

OBJECTIVE: To report fertility and pregnancy outcomes following transvaginal cervicoisthmic cerclage with a polypropylene sling during a previous pregnancy. METHODS: A continuous series of 57 women who underwent prophylactic cervicoisthmic cerclage during a previous (reference) pregnancy were enrolled. Telephone interviews were carried out to evaluate each patient's subsequent fertility. RESULTS: Among the 57 women interviewed, 8 had an inadequate follow-up, 13 women were lost to follow-up, 1 woman required a hemostatic hysterectomy, and 2 women required removal of the sling. Nineteen women did not desire a subsequent pregnancy. Of the 14 women who did desire a subsequent pregnancy, 1 woman had previously known tubal infertility. Of the 13 remaining women, 7 subsequently became pregnant. One woman had a spontaneous abortion (11 weeks of pregnancy); 1 woman delivered at 22 weeks of pregnancy, after a spontaneous premature membrane rupture; 1 woman had a cesarean delivery at 25 weeks of pregnancy; and 4 patients had a cesarean delivery after 37 weeks of pregnancy. Median duration of the 4 subsequent pregnancies at delivery was 37 weeks (interquartile range [IQR], 37-38 weeks). Median birth weight was 3040 g (IQR, 2500-3250 g). CONCLUSION: Subsequent pregnancy is possible after transvaginal cervicoisthmic cerclage using a synthetic sling.

Laparoscopic ovarian drilling using a 5-French bipolar energy probe.

OBJECTIVE: To report a new technique of laparoscopic ovarian drilling using a 5-Fr bipolar electrode. DESIGN: Retrospective study (case series). SETTING: University hospital. PATIENT(S): Patients presenting with polycystic ovarian syndrome. INTERVENTION(S): Laparoscopic ovarian drilling using a 5-Fr bipolar probe. MAIN OUTCOME MEASURE(S): Feasibility of operative technique. RESULT(S): No perioperative complication was noted. CONCLUSION(S): We describe a new technique of laparoscopic ovarian drilling using a bipolar electrosurgical probe.

Hysteroscopic management of residual trophoblastic tissue and reproductive outcome: a pilot study.

We report on the feasibility, efficiency, and reproductive outcomes of hysteroscopic resection of late residual trophoblastic tissue in 50 patients in an observational study over 6 years. Complete evacuation of the uterus was achieved in all patients by hysteroscopy. The median operative time was 21 (15-30) min. Only one surgical complication was registered: a uterine perforation in a patient with previous metroplasty. Hysteroscopic resection of persistent trophoblastic tissue seems to be a safe and efficient procedure that could be proposed as an alternative to conventional non-selective blind curettage. We would also recommend systematic second-look hysteroscopy to asess the exact prevalence of post-procedure intrauterine adhesions.

Antigen-presenting cells represent targets for R5 HIV-1 infection in the first trimester pregnancy uterine mucosa.

BACKGROUND: During the first trimester of pregnancy, HIV-1 mother-to-child transmission is relatively rare despite the permissivity of placental cells to cell-to-cell HIV-1 infection. The placenta interacts directly with maternal uterine cells (decidual cells) but the physiological role of the decidua in the control of HIV-1 transmission and whether decidua could be a source of infected cells is unknown. METHODOLOGY/PRINCIPAL FINDINGS: To answer to this question, decidual mononuclear cells were exposed to HIV-1 in vitro. Decidual cells were shown to be more susceptible to infection by an R5 HIV-1, as compared to an X4 HIV-1. Infected cells were identified by flow cytometry analysis. The results showed that CD14(+) cells were the main targets of HIV-1 infection in the decidua. These infected CD14(+) cells expressed DC-SIGN, CD11b, CD11c, the Fc gamma receptor CD16, CD32 and CD64, classical MHC class-I and class-II and maturation and activation molecules CD83, CD80 and CD86. The permissivity of decidual tissue was also evaluated by histoculture. Decidual tissue was not infected by X4 HIV-1 but was permissive to R5 HIV-1. Different profiles of infection were observed depending on tissue localization. CONCLUSIONS/SIGNIFICANCE: The presence of HIV-1 target cells in the decidua in vitro and the low rate of in utero mother-to-child transmission during the first trimester of pregnancy suggest that a natural control occurs in vivo limiting cell-to-cell infection of the placenta and consequently infection of the fetus.