1 MaternalFetal Medicine, Department of Obstetrics and Gynecology, 2 Department of Pathology, Chang Gung Memorial Hospital and Medical School of Chang Gung University, Taipei, Taiwan, Republic of China
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Abstract |
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Key words: ß-human chorionic gonadotrophin/electronic fetal monitoring/fetal anaemia/partial molar pregnancy/ultrasound
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Introduction |
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Case report |
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Ultrasonographic examination at 18th weeks revealed a live fetus with a huge hydropic placenta that appeared to have multiple cysts and occupied most of the uterine cavity. The features were consistent with molar changes and the fetus was found to have a normal brain, heart, and other major structures. The umbilical cord was connected to the area near to the honeycomb-like placenta (Figure 1). Pericardial effusion was the only finding in consultative fetal echocardiography, but it disappeared 2 weeks later. A chest X-ray showed no evidence of metastases and thyroid and liver function tests were normal. Genetic amniocentesis disclosed a normal female karyotype (46,XX). Partial molar pregnancy was diagnosed.
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The clinical course was smooth until the 32nd gestational week, when the patient was admitted to the labour room due to premature rupture of the membranes. Admission laboratory findings of the patient included white blood count 7.8x103/mm3, haemoglobin 10.3 g/dl, haematocrit 30.4%, mean cell volume 90.5 µm3, and platelet count 152x104/mm3. The serum titre of ß-HCG was 37 222 mIU/ml. Ultrasonography showed borderline intrauterine growth retardation (12 percentile) with decreased amniotic fluid index (as 3.3 cm). Neither ascites nor pericardial effusion was found. After admission, the fetal heart beat tracing revealed sinus tachycardia with decreasing beat-to-beat variability and occasional late deceleration, which changed to a sinusoid pattern 6 h later.
Because of acute fetal distress and suspicion of anaemia, a preterm female baby with body weight 1551 g was delivered by Caesarean section. The Apgar scores were 1 at 1 min, 4 at 5 min, and 6 at 10 min with intubation. The baby looked very pale and flaccid and was transferred to the neonatal ICU after resuscitation. The bulky area of the placenta appeared to be filled with a diffuse cluster of vesicles. The normal area of the placenta appeared to have been invaded and merged by the hydatidiform mole over the central area of the placenta, with resulting multiple haemorrhage (Figure 2).
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Pathological study of the placenta showed an immature organ with an admixture of normal and hydropic villi with dilated cisterns and scalloped borders (Figure 3). The trophoblastic proliferation was focal without atypical change. The serum titre of ß-HCG of the mother decreased to undetectable levels 1 month after delivery without any chemotherapy. She was doing well and had no evidence of recurrence after 18 months of follow-up. The female baby was normal without any complications at 18 months follow-up.
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Discussion |
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To date, eight cases of partial mole coexisting with the fetus with normal karyotype after 15 gestational weeks have been reported (Table 1), but only two of the infants survived. Most of the cases of partial molar pregnancy diagnosed early in the gestation have been terminated (Szulman and Surti, 1978a
; Teng and Ballon, 1984
; Deaton et al., 1989
), with or without medical complications. Partial molar pregnancy with fetal survival depends upon several factors: (i) normal karyotype of the fetus (Sarno et al., 1993
); (ii) smaller molar placenta compared to normal placenta (Jones, and Lauersen, 1975
; Deaton et al., 1989
); (iii) the onset of the molar degeneration and its speed of degeneration (Jones and Lauersen, 1975
; Sarno et al., 1993
); (iv) absence of anaemia occurring in the fetus (Crooij et al., 1985
); and (v) absence of maternal complications such as pre-eclampsia, thyrotoxicosis, and vaginal bleeding interrupting the pregnancy (Teng and Ballon, 1984
).
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The coexistence of a partial mole with a normal live fetus is rare. The present case was followed sonographically from the 18th gestational week until birth. Ultrasonographic examinations before and after delivery found no signs of congestive heart failure such as fetal ascites, pleural effusion or skin oedema nor any other evidence of chronic fetal blood loss throughout the pregnancy. Postnatal echocardiography revealed no evidence of major congenital cardiac malformation, cardiomegaly or pericardial effusion. The occurrence of acute blood loss in association with partial molar pregnancy could explain why fetal distress developed in this case.
Fetal anaemia caused by fetomaternal transfusion in a case of partial mole has been previously reported before (Crooij et al., 1985). Although the neonatal anaemia was effectively treated by exchange transfusion, the infant died from respiratory distress syndrome 67 days after birth. In our patient, severe fetal anaemia was probably due to fetal bleeding into the abnormal hydatidiform molar placenta. The haemorrhage might have been triggered by preterm rupture of the fetal membranes before admission. Evidence for this possibility was seen as multiple haemorrhage over the maternal side of the placenta specimen. However, we could not rule out the possibility of abruptio placentae because of fetal anaemia, placental appearance, and findings of fetal monitoring. Fetal anaemia resulting from the placental site haemorrhage could result in intrauterine fetal death. In our patient, ominous signs of fetal distress including fetal tachycardia, sinusoid pattern, and late deceleration were shown by fetal electronic monitoring. Under these conditions, if the haemodynamic status changed rapidly, the anaemic fetus would be at high risk of intrauterine fetal death. This is the primary reason that survival of a fetus with partial mole is so rare.
Although Feinberg et al. (Feinberg et al., 1988) suggested that an elevated AFP concentration, as in our patient, could represent a diagnostic marker for partial hydatidiform mole, a case reported by Sarno et al. (Sarno et al., 1993
) did not show any elevation of maternal serum AFP. The role of high AFP in cases of partial hydatidiform mole is not clear and needs further investigation.
Szulman and Surti (1982) reviewed 86 cases of partial hydatidiform mole and 115 cases of complete mole, and showed that the total incidence of residual disease was lower in the former (4.0%) than the latter (10.7%). However, Berkowitz et al. reported that more patients (9.9%) had developed persistent gestational trophoblastic disease (Berkowitz et al., 1985). Our patient did not show any persistent trophoblastic disease after birth and her serum ß-HCG titre returned to normal within 4 weeks. Termination of the partial molar pregnancy is sometimes necessary because of pre-eclampsia (2.56% of cases) or heavy vaginal bleeding (8% of cases) (Berkowitz et al., 1985
; Vejerslev, 1991
). Although the partial mole displays most of the pathological and clinical features of the complete mole, it seems to represent a milder version of the latter, as seen in placental morphology, ß-HCG titres, and the incidence of pre-eclampsia, thyrotoxicosis, hyperemesis, and haemorrhage. For this reason we do not think it is necessary to terminate partial molar pregnancy when the fetus is normal and there are no clinical complications.
It is very interesting that all of the reported cases of non-triploidy partial mole have had female karyotype (46,XX) except for one case (Table I) reported by Teng and Ballon (Teng and Ballon, 1984
). Deaton et al. (1989) questioned the validity of the study of Teng and Ballon because they did not perform chromosome banding studies to exclude the possibility of a complete mole with a twin gestation. The occurrence of a normal female baby in partial mole may represent a different manifestation from the classical complete mole and partial triploid mole (Feinberg et al., 1988
; Deaton et al., 1989
; Sarno et al., 1993
).
In conclusion, pregnancy with a normal live fetus and a partial molar placenta is extremely rare because of maternal and fetal complications. These complications include pre-eclampsia, hyperthyroidism, heavy vaginal bleeding, persistent gestational trophoblastic disease, preterm labour, and late abortion. A severely anaemic fetus caused by the abnormal placenta, as we reported, represents another clinical manifestation.
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Notes |
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References |
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Submitted on June 26, 1998; accepted on December 10, 1998.