Aneuploidy is frequent in heterozygous diploid and triploid hydatidiform moles

Hydatidiform moles are abnormal conceptuses. Many hydatidiform moles are diploid androgenetic, and of these, most are homozygous in all loci. Additionally, most hydatidiform moles are euploid. Using Single Nucleotide Polymorphism (SNP) array analysis, in two studies a higher frequency of aneuploidy was observed in diploid androgenetic heterozygous conceptuses, than in their homozygous counterparts. In the Danish Mole Project, we analyze conceptuses suspected to be hydatidiform moles due to the clinical presentation, using karyotyping and Short Tandem Repeat (STR) analysis. Among 278 diploid androgenetic conceptuses, 226 were homozygous in all loci and 52 (18.7%) were heterozygous in several loci. Among 142 triploid diandric conceptuses, 141 were heterozygous for paternally inherited alleles in several loci. Here we show that the frequencies of aneuploidy in diploid androgenetic heterozygous and triploid diandric heterozygous conceptuses were significantly higher than the frequency of aneuploidy in diploid androgenetic homozygous conceptuses. In diploid androgenetic and triploid diandric conceptuses that are heterozygous for paternally inherited alleles, the two paternally inherited sets of genomes originate in two spermatozoa. Each spermatozoon provides one pair of centrioles to the zygote. The presence of two pairs of centrioles may cause an increased risk of aneuploidy.

When to consult a geneticist specialising in gestational trophoblastic disease

BACKGROUND

Gestational trophoblastic disease comprises hydatidiform moles and a rare group of malignancies that derive from trophoblasts. Although there are typical morphological features that may distinguish hydatidiform moles from non-molar products of conception, such features are not always present, especially at early stages of pregnancy. Furthermore, mosaic/chimeric pregnancies and twin pregnancies make pathological diagnosis challenging while trophoblastic tumours can also pose diagnostic problems in terms of their gestational or non-gestational origin.

OBJECTIVES

To show that ancillary genetic testing can be used to aid diagnosis and clinical management of GTD.

METHODS

Each author identified cases where genetic testing, including short tandem repeat (STR) genotyping, ploidy analysis, next generation sequencing and immunostaining for p57, the product of the imprinted gene CDKN1C, facilitated accurate diagnosis and improved patient management. Representative cases were chosen to illustrate the value of ancillary genetic testing in different scenarios.

OUTCOME

Genetic analysis of placental tissue can aid in determining the risk of developing gestational trophoblastic neoplasia, facilitating discrimination between low risk triploid (partial) and high risk androgenetic (complete) moles, discriminating between a hydatidiform mole twinned with a normal conceptus and a triploid conception and identification of androgenetic/biparental diploid mosaicism. STR genotyping of placental tissue and targeted gene sequencing of patients can identify women with an inherited predisposition to recurrent molar pregnancies. Genotyping can distinguish gestational from non-gestational trophoblastic tumours using tissue or circulating tumour DNA, and can also identify the causative pregnancy which is the key prognostic factor for placental site and epithelioid trophoblastic tumours.

CONCLUSIONS AND OUTLOOK

STR genotyping and P57 immunostaining have been invaluable to the management of gestational trophoblastic disease in many situations. The use of next generation sequencing and of liquid biopsies are opening up new pathways for GTD diagnostics. Development of these techniques has the potential to identify novel biomarkers of GTD and further refine diagnosis.

Diagnosis of hydatidiform moles using circulating gestational trophoblasts isolated from maternal blood

INTRODUCTION

Identifying hydatidiform moles (HMs) is crucial due to the risk of gestational trophoblastic neoplasia. When a HM is suspected on clinical findings, surgical termination is recommended. However, in a substantial fraction of the cases, the conceptus is actually a non-molar miscarriage. If distinction between molar and non-molar gestations could be obtained before termination, surgical intervention could be minimized.

METHODS

Circulating gestational trophoblasts (cGTs) were isolated from blood from 15 consecutive women suspected of molar pregnancies in gestational week 6-13. The trophoblasts were individually sorted using fluorescence activated cell sorting. STR analysis targeting 24 loci was performed on DNA isolated from maternal and paternal leukocytes, chorionic villi, cGTs, and cfDNA.

RESULTS

With a gestational age above 10 weeks, cGTs were isolated in 87% of the cases. Two androgenetic HMs, three triploid diandric HMs, and six conceptuses with diploid biparental genome were diagnosed using cGTs. The STR profiles in cGTs were identical to the profiles in DNA from chorionic villi. Eight of the 15 women suspected to have a HM prior to termination had a conceptus with a diploid biparental genome, and thus most likely a non-molar miscarriage.

DISCUSSION

Genetic analysis of cGTs is superior to identify HMs, compared to analysis of cfDNA, as it is not hampered by the presence of maternal DNA. cGTs provide information about the full genome in single cells, facilitating estimation of ploidy. This may be a step towards differentiating HMs from non-HMs before termination.

Preoperative predictors of inguinal lymph node metastases in vulvar cancer - A nationwide study

BACKGROUND

A combination of tumour size, differentiation grade and location may identify a group of vulvar squamous cell cancer (VSCC) patients with a very low risk of inguinal lymph node metastasis. We aim to examine these findings in a large national cohort of VSCC patients.

MATERIALS AND METHODS

Population based prospective data on VSCC patients treated with vulvectomy and primary groin surgery was obtained from the Danish Gynaecological Cancer Database. Univariate chi-square and multivariate logistic regression analysis were used. Statistical tests were 2-sided. P-values of <0.05 were considered statistically significant.

RESULTS

In all, 388 VSCC patients were identified. Of these 264 (63.3%) were node negative and 121 (36.7%) node positive. Increasing tumour size (diameter ≤ 2 cm vs. > 2 to 4 cm), grade (1 vs. 2-3) and location of tumour to clitoris were all associated with a significantly increased risk of inguinal lymph node metastasis OR 2.81(95% CI 1.52-5.20), OR 3.19 (95% CI 1.77-5.74) and OR 2.74 (95% CI 1.56-5.20), respectively. Previous vulvar disease was not associated with lymph node metastasis. No lymph node metastasis was demonstrated in patients with grade 1 tumours, tumour size less than 2 cm and located outside the clitoris area (n = 51).

CONCLUSIONS

VSCC patients with grade 1 tumours, ≤ 2 cm and without clitoral involvement have a very low risk of inguinal lymph node metastasis. These patients may be spared inguinal lymph node staging to decrease operating time and peri- and postoperative morbidity in the future. However, studies validating our findings are needed.

Differences in Administration of Methotrexate and Impact on Outcome in Low-Risk Gestational Trophoblastic Neoplasia

Simple Summary

Low-risk gestational trophoblastic neoplasia is a rare but highly curable malignancy. The most common first line treatment is methotrexate, which can be administered in different forms. In order to investigate the impact of route of administration on methotrexate resistance, toxicity demanding treatment switch, complete remission and relapse, we performed an observational study including women with low-risk gestational trophoblastic neoplasia in a population-based setting in Sweden and Denmark. We found that oral compared to intra-muscular administration of methotrexate gives a higher rate of drug resistance, but does not affect rates of complete remission, recurrence or overall survival. Intra-muscular treatment was associated with more toxicity leading to switch of treatment. We conclude that, although a larger proportion of women develop drug resistance, oral methotrexate, which is easy to administer and highly tolerable, could be an option for well-informed and motivated women.

Abstract

Methotrexate (MTX) is frequently used as first-line treatment for low-risk gestational trophoblastic neoplasia (GTN). Intravenous and intramuscular (im) routes of administration are the most common methods, although oral administration is used by some Scandinavian centers. The primary aim of this study was to assess the impact of form of administration (im/oral) on resistance to methotrexate (MTX-R) treatment in low-risk GTN. Secondary aims were time to hCG normalization, rates of toxicity-induced treatment switch, and rates of complete remission and recurrence. In total, 170 women treated at Karolinska University Hospital in Sweden and Aarhus University Hospital in Denmark between 1994 and 2018 were included, of whom 107 were given im and 63 oral MTX. MTX-R developed in 35% and 54% in the im and oral groups, respectively (p = 0.01). There was no difference in days to hCG normalization (42 vs. 41 days, p = 0.50) for MTX-sensitive women. Toxicity-induced treatment switch was only seen in the im group. Complete remission was obtained in 99.1% and 100% (p = 0.44), and recurrence rate within one year was 2.8% and 1.6% (p = 0.29). The form of administration of MTX had a significant impact on development of MTX-R and treatment-associated toxicity, but does not affect rates of complete remission, recurrence or survival.

Lichen Sclerosis is Associated With a High Rate of Local Failure After Radio(chemo)therapy for Vulvar Cancer

AIMS

Radio(chemo)therapy plays an important role in the treatment of vulvar cancer, either as postoperative treatment or as definitive treatment in patients who present with inoperable disease. Only limited data are available regarding outcome after modern state of the art radio(chemo)therapy and more information regarding prognostic factors are warranted. The aim of this study was to evaluate disease outcomes after radio(chemo)therapy in patients with vulvar cancer with special emphasis on the impact of lichen sclerosis on local control.

MATERIALS AND METHODS

All consecutive patients (n = 109) from the western half of Denmark who were treated with definitive (n = 52) or postoperative (n = 57) radio(chemo)therapy between January 2013 and January 2020 were included. Local control, cause-specific survival and overall survival, as well as morbidity, were analysed using Kaplan-Meier statistics. Prognostic factors for local control were analysed in univariate and multivariate analysis.

RESULTS

At a median follow-up of 35 (4-95) months, 46 (42.0%) patients were diagnosed with recurrence. Eighty per cent of the recurrences were located to the vulva region, leading to a 5-year local control of 58.9% (confidence interval 47.9-69.9). Cause-specific survival was 62.9% (confidence interval 53.1-72.7), whereas overall survival was 58.0% (confidence interval 47.6-68.5). Grade 3-4 morbidity was diagnosed in 10 (9%) patients. Lichen sclerosis (hazard ratio 3.89; confidence interval 1.93-7.79) was an independent risk factors for local recurrence. Patients without lichen sclerosis had a 5-year local control rate of 83.6% (confidence interval 67.2-99.0) and 62.6% (confidence interval 43.2-82.0) after postoperative and definitive radio(chemo)therapy, respectively. In patients with lichen sclerosis, the local control rate was 44.0% (confidence interval 19.3-69.0) and 17.6% (confidence interval 0-30.0) after postoperative and definitive radio(chemo)therapy, respectively.

CONCLUSION

Radio(chemo)therapy plays an important role in the treatment of vulvar cancer. However, despite dose escalation, a substantial proportion of patients experienced local relapse. Pre-existing lichen sclerosis seems to have a significant impact on the risk of recurrence. This should influence surveillance programmes for these patients.

Hydatidiform mole diagnostics using circulating gestational trophoblasts isolated from maternal blood

Background

In gestational trophoblastic disease, the prognosis is related to the genetic constitution. In some cases, taking a biopsy is contraindicated.

Methods

In a pregnant woman, ultrasound scanning suggested hydatidiform mole. To explore if the genetic constitution can be established without taking a biopsy (or terminating the pregnancy), cell‐free DNA and circulating gestational trophoblasts were isolated from maternal blood before evacuation of the uterus. The evacuated tissue showed the morphology of a complete hydatidiform mole. Without prior whole‐genome amplification, short tandem repeat analysis of 24 DNA markers was performed on the samples, and on DNA isolated from evacuated tissue, and from the blood of the patient and her partner.

Results

Identical genetic results were obtained in each of three circulating gestational trophoblasts and the evacuated tissue, showing that this conceptus had a diploid androgenetic nuclear genome. In contrast, analysis of cell‐free DNA was less informative and less specific due to the inherent presence of cell‐free DNA from the patient.

Conclusion

Our results show that it is possible to isolate and analyze circulating gestational trophoblasts originating in a pregnancy without maternal nuclear genome. For diagnosing gestational trophoblastic diseases, genotyping circulating gestational trophoblasts appears to be superior to analysis of cell‐free DNA.

Cell-free DNA in pregnancy with choriocarcinoma and coexistent live fetus: A case report

BACKGROUND

This case report describes the use of analysis of cell-free DNA in the blood of a patient with a pregnancy with one live fetus and a choriocarcinoma diagnosed at 22 weeks of gestation.

RESULTS

The result of the analysis of 16 microsatellite loci on 14 chromosomes in the cell-free DNA in plasma was consistent with the result of the analysis of a tumor biopsy indicating biparental diploid origin of the genome. The DNA markers were discordant with the markers of the placenta indicating two separate conceptions.

CONCLUSION

Our results indicate that analysis of cell-free DNA in plasma allows determination of the origin of a choriocarcinoma without tissue biopsy, even in the presence of a co-existent pregnancy.

Paternal Hemizygosity in 11p15 in Mole-like Conceptuses: Two Case Reports

Hydatidiform mole is an abnormal human pregnancy characterized by the fetus being absent or nonviable, and the chorionic villi being vesicular and with trophoblastic hyperplasia. Most often, the mole phenotype is seen in conceptuses with an excess of paternally inherited genome set(s) relative to maternally inherited genome set(s), suggesting that the phenotype is caused by an excess of genome with a paternal imprinting pattern. However, it is unknown if correct parental origin of every imprinted gene is crucial for normal early differentiation or if abnormal parental imprinting of only one, or some, gene(s) can cause the mole phenotype.Two conceptuses included in the Danish Mole Project stood out since they presented with vesicular chorionic villi and without signs of fetal differentiation, and had apparently biparental diploid genomes, and no mutations in NLRP7 or KHDC3L were detected in the mothers. These conceptuses were subjected to a centralized histopathological revision and their genetic complements were scrutinized using fluorescence in situ hybridization, and DNA-marker and array comparative genomic hybridization analyses. Both conceptuses showed dysmorphic chorionic villi with some similarities to hydatidiform moles; however, no definite florid trophoblast hyperplasia was observed. Both conceptuses showed paternal hemizygosity of 11pter-11p15.4, most likely in nonmosaic state.Our findings suggest that the product of one (or a few) maternally expressed gene(s) on the tip of chromosome 11 is necessary for normal early embryonic differentiation. However, since the present two cases did not exhibit all features of hydatidiform moles, it is likely that abnormal parental imprinting of genes in other regions contribute to the phenotype of a hydatidiform mole.

Gestational trophoblastic diseases - clinical guidelines for diagnosis, treatment, follow-up, and counselling

Hydatidiform mole is treated with surgical uterine evacuation with suction and blunt curettage (D). Medical uterine evacuation should not be used (C). On clinical suspicion of hydatidiform mole, one representative sample of the evacuated tissue is fixed for histopathologic investigation and one is forwarded unfixed for genetic analysis (D). Serum hCG is measured on suspicion of hydatidiform mole. At the time of the uterine evacuation, the initial hCG is measured (A). After a hydatidiform mole that is both triploid and partial, serum hCG is measured weekly until there are two consecutive undetectable values (< 1 or < 2), after which the patient can be discharged from follow-up (C). After a diploid hydatidiform mole, a complete mole, or a hydatidiform mole without valid ploidy determination, serum hCG is measured weekly until the value is undetectable (< 1 or < 2). If serum hCG is undetectable within 56 days after evacuation, the patient can be discharged from follow-up after an additional four monthly measurements. If serum hCG is first normalised after 56 days, the patient is follow-up with monthly serum hCG measurement for six months. Safe contraception should be used during the follow-up period (A). If hCG stagnates (less than 10% fall over three measurements), increases, or if hCG can be demonstrated for longer than 6 months, the patient by definition has persistent trophoblastic disease (PTD). A chest X-ray should be taken and a gynaecologic ultrasound scanning performed. The patient is referred to oncologic treatment (A). Uterine re-evacuation as a treatment for PTD can, in general, not be recommended because the rate of remission is low, and there is the risk of perforation of the uterus (C). In all following pregnancies, the woman is offered an early ultrasound scan, e.g. in gestational week eight (D). Eight weeks after termination of all future pregnancies, serum hCG is measured (D). In PTD and invasive hydatidiform mole, the primary treatment is MTX, either orally every third week or IV every week (B). In MTX-resistant PTD, IV act D is added (or replaces the MTX) (B). Third line chemotherapy is BEP or EP, alternatively EMA-CO (B). Choriocarcinoma is primarily treated with chemotherapy. Hysterectomy and/or resection of metastases are possible treatments (A). Placental site trophoblastic tumour (PSTT) and epithelioid trophoblastic tumour (ETT) are primarily treated with hysterectomy. In the case of disseminated disease, chemotherapy is considered (A). The risk of reoccurrence after trophoblastic disease treated with chemotherapy is approximately 3%. Most reoccurrences are seen within 12 months, and for this reason monitoring of hCG is recommended for one year, the first third months once or twice a month, thereafter every second to third month. Patients with PSTT and ETT are monitored with measurement of hCG throughout their lifetimes (C). In genetically verified twin pregnancy with hydatidiform mole and a living foetus, the pregnancy can continue if serum hCG is monitored and ultrasound scans regularly performed, and possible obstetric complications dealt with (C). In the case of recurrent hydatidiform mole and/or familial hydatidiform mole, patients should be referred to genetic workup and counselling (C). Women with a hereditary disposition to hydatidiform mole because of a mutation in NLRP7 should be informed of the possibility of becoming pregnant via egg donation (C).

A 30-year experience in using oral methotrexate as initial treatment for gestational trophoblastic neoplasia regardless of risk group

BACKGROUND

Treatment of postmolar gestational trophoblastic neoplasia (GTN) is often stratified according to FIGO score using methotrexate (MTX) for low-risk patients and first-line multi-agent chemotherapy (e.g. EMA-CO) for high-risk patients. In contrast, oral MTX may be given as first-line therapy to all GTN patients regardless of risk group. The aim was to examine the efficacy of oral MTX and a response-adapted treatment policy, which has been used for three decades at Aarhus University Hospital (AUH).

MATERIAL AND METHODS

Seventy-one consecutive postmolar GTN patients treated 1981-2011 were included. Data were obtained from medical records, using histopathology and human choriogonadotropin (hCG) to verify the diagnosis. All patients received oral MTX as first-line chemotherapy. Second- and third-line chemotherapy was given according to response.

RESULTS

Sixty-four (90%) patients were retrospectively categorized as FIGO low-risk disease, whereas seven patients (10%) had high-risk disease. Complete response to first-line oral MTX chemotherapy was observed in 35/71 (49%) patients, while 62/71 (87%) had complete remission on MTX (first-line) and/or MTX plus dactinomycin (second-line), without the use of multi-agent therapy. Nine patients (13%) received third-line multi-agent chemotherapy, six low-risk (67%) and three high-risk (33%) patients. There were no recurrences and no patients died as a consequence of toxicity or disease.

CONCLUSION

Fifty percent of all patients can be cured on oral MTX alone. By adding dactinomycin, about 90% are cured without use of multi-agent chemotherapy. The use of oral MTX as initial treatment can minimize the number of patients receiving multi-agent chemotherapy.

Triploid pregnancies: genetic and clinical features of 158 cases

OBJECTIVE

The purpose of this study was to analyze the correlation between the genetic constitution and the phenotype in triploid pregnancies.

STUDY DESIGN

One hundred fifty-eight triploid pregnancies were identified in hospitals in Western Denmark from April 1986 to April 2010. Clinical data and karyotypes were collected retrospectively, and archived samples were retrieved. The parental origin of the genome, either double paternal contribution (PPM) or double maternal contribution (MMP) was determined by an analysis of methylation levels at imprinted sites.

RESULTS

There were significantly more PPM than MMP cases (P < .01). In MMP cases, the possible karyotypes had similar frequencies, whereas, in PPM cases, 43% had the karyotype 69,XXX, 51% had the karyotype 69,XXY, and 6% had the karyotype 69,XYY. Molar phenotype was seen only in PPM cases. However, PPM cases with a nonmolar phenotype were also seen. For both parental genotypes, various fetal phenotypes were seen at autopsy. Levels of human chorionic gonadotropin in maternal serum were low in MMP cases and varying in PPM cases, some being as low as in the MMP cases.

CONCLUSION

In a triploid pregnancy, suspicion of hydatidiform mole at ultrasound scanning, by macroscopic inspection of the evacuated tissue, at histology, or because of a high human chorionic gonadotropin in maternal serum level each predict the parental type PPM with a very high specificity. In contrast, the sensitivity of these observations was <100%.

Twin pregnancies with diploid hydatidiform mole and co-existing normal fetus may originate from one oocyte

BACKGROUND

In twin pregnancies comprising a hydatidiform mole and a normal co-fetus, the ploidy of the mole is almost exclusively reported as diploid and very rarely as triploid. We aimed at understanding this unbalanced distribution of diploid and triploid moles in twin pregnancies by investigating the number of gametes involved.

METHODS

Using polymorphic DNA markers, we compared the alleles of seven moles with those of the normal co-fetuses and deduced the number of oocytes and spermatozoa represented in each twin pregnancy.

RESULTS

The genomes of all seven moles were androgenetic diploid; six moles were homozygous in all loci analyzed and one mole was heterozygous in several loci. In one homozygous mole, the paternal alleles were identical to those of the normal co-fetus in 13 non-linked informative microsatellite loci, indicating the involvement of one spermatozoon only, and thus of one oocyte only. Duplications of the paternal genome followed by abnormal cell division can explain this observation. In six moles, the paternal alleles were different from those of the normal co-fetus suggesting involvement of two (or more) spermatozoa. Overfertilization of one oocyte followed by abnormal cell division is a possibility.

CONCLUSIONS

It is possible that twin pregnancies comprising a diploid mole and a normal co-fetus most often derive from one single oocyte fertilized with one or more spermatozoa. This can explain why diploid moles are far more frequent than triploid moles in twin pregnancies.

Screening history of women with cervical cancer: a 6-year study in Aarhus, Denmark

To identify possible weaknesses in cervical screening in Aarhus County, 10 years after the programme was introduced, screening histories were examined. A major problem for the screening programme was that 31% of women were never screened and 61% under-screened, the latter group being significantly dominated by older women and high-stage tumours.

Differences in current clinical features of diploid and triploid hydatidiform mole

OBJECTIVE

To describe and compare the current clinical features of diploid and triploid molar pregnancy and to evaluate whether the presenting clinical features can predict the ploidy of a molar pregnancy.

DESIGN

A retrospective study of the clinical features and ploidy of hydatidiform moles.

SETTING

The Departments of Clinical Genetics and Pathology, Aarhus University Hospital and 13 gynaecological wards, Jutland, Denmark.

POPULATION

A total of 259 women with molar pregnancy diagnosed between April 1986 and June 2003.

METHODS

A review of medical records of consecutively collected, clinically suspected cases of molar pregnancy was performed. The molar ploidy was determined by karyotyping, flow cytometry, and/or analysis of polymorphic DNA markers.

MAIN OUTCOME MEASURES

Maternal characteristics, presenting symptoms, initial human chorionic gonadotrophin (hCG), and molar ploidy.

RESULTS

In a multiple logistic regression model, initial hCG of > or = 100,000 iu/l (P < 0.001), first-trimester gestational age (P < 0.001), vaginal bleeding (P < 0.001), and maternal age of > or = 40 years (P = 0.03) were independent predictors of diploid mole. Women with excessive uterine size more frequently had a diploid than a triploid mole (P < 0.001). Fifty-four percent of the women with triploid mole and 27% of the women with diploid mole were diagnosed before onset of symptoms (P < 0.001).

CONCLUSIONS

The current clinical features of diploid mole are different from those of triploid mole. The presenting clinical profile of a molar pregnancy may be used as an early predictor of the molar ploidy and thus of the prognosis.

Evaluation of the risk of persistent trophoblastic disease after twin pregnancy with diploid hydatidiform mole and coexisting normal fetus

OBJECTIVE

This study was undertaken to evaluate the risk of persistent trophoblastic disease and obstetric complications related to a multiple pregnancy comprising a diploid hydatidiform mole and normal cofetus(es).

STUDY DESIGN

From a database of 270 consecutively collected hydatidiform moles, 8 multiple and 154 singleton molar pregnancies were identified. Molar and fetal ploidy was determined, and data on clinical features and chemotherapy were collected. Differences between groups were assessed with Fisher's exact or Mann-Whitney test.

RESULTS

The molar component in all 8 multiple pregnancies was diploid. Five patients with diploid mole and coexisting fetus pregnancy chose to terminate their pregnancy, 2 aborted spontaneously, and 1 patient delivered a healthy child. Two diploid mole and coexisting fetus pregnancies (25%) and 17% of the singleton molar pregnancies were followed by persistent trophoblastic disease (P = .63).

CONCLUSION

The risk of persistent trophoblastic disease after a diploid mole with coexisting fetus pregnancy is similar to that after a singleton molar pregnancy, and expectant management instead of therapeutic abortion can be pursued.

The risk of persistent trophoblastic disease after hydatidiform mole classified by morphology and ploidy

OBJECTIVE

Hydatidiform mole can be classified by histopathologic characteristics and by genetic constitutions and most complete moles are diploid, whereas most partial moles are triploid. We investigated the concordance between these two classifications, characterized moles with conflicting classifications, and compared the ability of the two classifications to discriminate between patients with and without a substantial risk of persistent trophoblastic disease.

METHODS

294 cases of consecutively collected hydropic placentas clinically suspected of hydatidiform mole made the basis of this retrospective study. We determined the ploidy and reviewed the original histopathologic material in all cases. Data on possible chemotherapy were collected for each patient.

RESULTS

270 of the conceptuses were histopathologically classified as hydatidiform mole. Among the 24 conceptuses classified as non-molar miscarriage, 20 were triploids, 2 were diploid androgenetic and 2 were diploid biparental. In 23% of the conceptuses, the histopathologic and genetic classifications were conflicting. 5% of the patients with hydropic placentas classified as partial mole encountered persistent trophoblastic disease; however, the genome was diploid in all these moles. None of 131 patients with a triploid hydropic gestation encountered persistent trophoblastic disease.

CONCLUSION

As full concordance between the histopathologic and the genetic classifications was not found, we believe that features beyond the genetic constitution influence the development of morphologic features in hydatidiform moles. We recommend that gestations suspected of hydatidiform mole are subjected to histopathologic examination. If hydatidiform change and trophoblastic hyperplasia are identified, the ploidy should be used to identify patients with a high risk of persistent trophoblastic disease.

Predictors of Low Risk of Persistent Trophoblastic Disease in Molar Pregnancies

OBJECTIVE

To search for predictive factors for low risk of persistent trophoblastic disease in patients with molar pregnancies.

METHODS

A total of 270 consecutively collected, histologically confirmed hydatidiform moles were classified by ploidy using karyotyping and flow cytometry. The parental origin of the genome was determined by analysis of microsatellite polymorphisms. Data on clinical features and pathology reports were collected for each patient.

RESULTS

The observed frequency of persistent trophoblastic disease in patients with triploid moles was 0 of 105, (95% confidence interval 0-2.8%), whereas 28 of 162 patients with diploid molar pregnancies developed persistent trophoblastic disease (P < .001). Patients with a diploid mole and an initial hCG level lower than 49,000 units per liter did not develop persistent trophoblastic disease (P = .03).

CONCLUSION

The risk of persistent trophoblastic disease after a triploid mole is very low. By combining the present data with data from published studies with valid ploidy assessment, the frequency of persistent trophoblastic disease in patients with triploid moles is 0 of 196 (95% confidence interval 0-1.5%). We suggest that the surveillance program for patients with triploid molar pregnancies is shortened. Initial hCG less than 49,000 units per liter is a possible predictor of low risk of persistent trophoblastic disease in women with diploid molar pregnancies, but this observation needs confirmation in larger studies.

[Primary Cesarean section--what happens next time...?]

INTRODUCTION

The aim of this study was to examine how often information about the best way of giving birth after a primary caesarean section was given and to describe the frequency of repeated caesarean section.

MATERIAL AND METHODS

Notifications of 108 women with primary caesarean section in the three-year period 1994-1996.

RESULTS

Documentated information was given to 41%. A total of 43% had a repeated caesarean section, most frequently seen in the dystocia group (80%) as compared to the breech group (15%), which shows a significant difference, p < 0.01.

CONCLUSION

This study shows that less than half of the women had been informed about future delivery following a primary caesarean section. The rate of repeated caesarean sections varies with the indication of the primary caesarean. Improved information is suggested in order to avoid that women desist from further pregnancies because of uncertainty.

Molecular identification of Photorhabdus luminescens strains by amplification of specific fragments of the 16S ribosomal DNA

Sequence variation within the variable region of the 16S rRNA at position 440 to 480 allowed the synthesis of specific PCR primers for the identification of groups within the species Photorhabdus luminescens, symbionts of entomopathogenic nematodes of the genus Heterorhabditis. For the second PCR primer the highly conserved region at 755 to 795 was used. The P. luminescens type strain specific primer could not recognize any other P. luminescens strain. The primer TEMPERATUS based on the sequence of strain DSM12190 (isolated from North West European H. megidis strain HSH2) identified all P. luminescens associated with H. megidis from North West Europe and two isolates from closely the related nematode strains from Ireland. The primer TROPICUS based on strain DSM12191 (isolated from the nematode type strain H. indica strain LN2) identified P. luminescens of tropical origin isolated from H. indica. Symbionts of H. bacteriophora could not yet be separated into well described groups with the primers used. A comparison of sequence data resulted in the identification of additional groups. The non-symbiotic P. luminescens isolates are distinct in the variable region. The group HELIOTHIDIS contains 15 P. luminescens associated with H. bacteriophora from North East America. The MARELATUS group contains symbionts of the nematode H. marelatus from the West Coast of the US. The data together with the specific symbiotic association of P. luminescens strains with different nematode species support the division of the taxon P. luminescens into different species.